A critical review of the estimation of the thermodynamic parameters on adsorption equilibria. Wrong use of equilibrium constant in the Van't Hoof equation for calculation of thermodynamic parameters of adsorption

Profiteering optical biosensors for swift assaying clanobutin residues in food samples, baby food and surface water: Comparative greenness, whiteness and blueness assessment

In livestock systems, clanobutin sodium (CLB) is a pivotal veterinary medication due to its appetite-stimulant features. This contribution aims to design, for the first time, a straightforward and ecological framework for quantifying CLB in various matrices. Relying on a direct mix-and-read assay, tyrosine (TS) and tryptophan (TP) biosensors were exploited as turn-off fluorescence probes for quantifying CLB using λex/em 274/302 nm and 272/361 nm, respectively. Upon adopting the optimized experimental conditions, there was a quantitative quenching in the native fluorescence of TS and TP through the concentration ranges (0.8 - 10.0 µg mL-1) and (3.0 - 20.0 µg mL-1) of CLB, with correlation coefficients (r) = 0.9997 and 0.9995, respectively. The established approaches were effectively applied for estimating CLB in veterinary formulations with standard deviations ± 1.84 and ± 1.50 for TS and TP, respectively. They have also authenticated significant practical applicability for assessing CLB residues in assorted food samples (including bovine muscle, poultry muscle, eggs, and milk), baby food, and river water with SD not exceeding 3. The paramount application findings highlighted the significance of the suggested work in many sectors such as food quality assurance, drug quality control, environmental monitoring, and therapeutic drug monitoring. A comparative study was executed between the proposed and published methodologies concerning the greenness, whiteness, and blueness appraisals. To achieve a fair arbitrage, we refuge to plentiful software and assessment tools, including Green Certificate Classification (GCC), Analytical Greenness Metric Approach (AGREE), the Red-Green-Blue (RGB) 12 algorithm and Blue Applicability Grade Index (BAGI). The outcomes accentuate the proposed work as a pioneering effort in inspecting a holistic evaluation of sustainability in the analytical chemistry field.

Facile construction of zirconium/iron bimetallic organic frameworks for fluoride efficient removal from aqueous phase: An integrated experimental and theoretical investigation

This work presents the synthesis of Zr/Fe bimetallic organic frameworks (Zr/Fe-UiO-66) with varying compositions via a straightforward solvothermal method, targeting fluoride ions (F-) removal from the aqueous phase. Adsorption experiments elucidated the effect of factors (i.e., adsorbent dosage, initial concentration (C0), temperature, contact time and pH) on fluoride adsorption, and the parameters were optimized. The results show that the Zr/Fe-UiO-66(C) achieved the maximal uptake capacity of 164.4 mg/g, with the conditions of pH = 5.0, T = 298 K, C0 = 190 mg/L. The adsorption behavior of fluoride on Zr/Fe-UiO-66 can be well followed with the pseudo-second-order (PSO) kinetic model and the Sips isotherm model, described as the spontaneous, chemical driven and endothermic process. The adsorption mechanism was comprehensively explained by characterizations and microscopic simulations, such as molecular dynamics methods (MD) and independent gradient model analysis (IGM), which involves the chemical bonding, hydrogen-bond interaction and electrostatic interactions. Furthermore, Zr/Fe-UiO-66(C) exhibited excellent fluoride ion selectivity and superior stability. After 5 cycles of adsorption, Zr/Fe-UiO-66(C) maintained the removal efficiency of 83.4 % for F-. This research provides significant insights into the development of bimetallic metal-organic framework materials and fluoride removal research.

Specific capture of magnesium ions by phosphorus atomic sites on self-floating nuclei advances Mg/Li separation in salt lakes brine

Efficient magnesium-lithium separation is a critical step in extracting lithium ions from salt lakes brine. Precipitation of Mg2+ from liquid to solid is the simplest separation method, but a side reaction of Li+ adsorption by precipitated floc leads to incomplete Mg/Li separation and lithium loss. In this study, we grafted phosphorus atomic sites onto silica-based nuclei with self-floating separation capability to prepare adsorbents with specific capture ability for Mg2+, achieving efficient Mg/Li separation from brine. Surface composition analysis shows that the content of P element is 0.99 %, which contributed 82.20 mg g⁻1 of Mg2+ adsorption capacity of at room temperature. During this process, the content of Na and Ca elements in the material decreased by 1.47 % and 0.85 %, respectively, due to ion exchange and surface coverage. In samples of the same water quality as Smackover brine, the Li content in the Mg2+-captured material was only 3.20 % of that in directly precipitated Mg(OH)2, due to the adsorption selectivity coefficient of the material for Mg²⁺ to Li⁺ reaching 62.26. The outcomes of this research enlighten the selective capture ability and mechanism of phosphorus atomic sites for Mg2+, providing new insights for efficient Mg/Li separation from salt lakes to improve raw brain grade.

PAD resin: An intelligent adsorbent for solving Cr(VI) pollution with real-time feedback and high efficiency

To address the urgent issue of Cr(VI) pollution and protect aquatic ecosystems, we conducted an exhaustive investigation into a Poly(acrylamide-co-methacryloyloxyethyl trimethylammonium chloride) (PAD) resin synthesized through an environmentally friendly aqueous polymerization process. This resin not only boasts a high capacity for Cr(VI) removal but also incorporates a colorimetric sensing mechanism that visually transitions from transparent to yellow upon Cr(VI) adsorption, offering real-time, non-invasive monitoring and optimization of the remediation process. According to the Langmuir model, at a pH of 4.78 and a temperature of 15 ℃, the maximum adsorption capacity of PAD for Cr (VI) is 135.32 mg/g. Its adsorption kinetics conform to a pseudo-first-order model and Langmuir isotherm, indicating uniform adsorption sites and favorable interactions. Thermodynamic analysis further reveals the spontaneous and exothermic nature of the adsorption process, making it suitable for large-scale applications at ambient temperatures.In natural lake water-based Cr(VI) simulated wastewater, PAD resin achieved a remarkable removal efficiency of 99.54 % for 4.82 mg/L Cr(VI) （The filling column had a diameter of 3 cm and a height of 30 cm; The PAD dosage was 1.6 g, with a flow rate of 5 mL/min and an adsorption time of 60 min, at a neutral pH）, effectively reducing residual Cr(VI) concentrations to 0.022 mg/L, well under WHO limits (0.05 mg/L). Additionally, its 93.68 % capacity retention after four HCl regeneration cycles underscores economic feasibility & sustainability.In summary, PAD resin stands out as an innovative, high-performance, and intelligent Cr(VI) adsorbent that transcends the limitations of traditional adsorbents.

Sustainable synthesis and dual adsorption of methyl orange and cadmium ions using biogenic silica-based fibrous silica functionalized with crown ether ionic liquid

In pursuit of sustainable nanomaterial production, this study presents a novel biogenic fibrous silica sphere functionalized with a crown ether ionic liquid for advanced dual-adsorption of methyl orange and Cd(II) from aqueous solution. Sorghum waste serves as the silica source in the adsorbent preparation process, ensuring an eco-friendly approach. The benzo-15-crown-5 ionic liquid is coupled to thiol-functionalized fibrous silica spheres through an efficient thiol-ene click reaction. Under constant conditions (temperature: 298 K, solution volume = 50 mL, adsorbent dosage = 5 mg, pH = 7, shaking speed = 200 rpm), the synthesized material demonstrates maximum adsorption capacities of 507.1 mg g-1 and 306.3 mg g-1 for methyl orange and Cd(II), respectively, according to the Langmuir model. Thermodynamic investigations reveal exothermic adsorption for methyl orange with an enthalpy change of -77.49 KJ mol-1, while endothermic adsorption is observed for Cd(II) with an enthalpy of +24.10 KJ mol-1. The entropy change of adsorption is -0.153 KJ mol-1 K-1 for methyl orange, indicating a more ordered state, and + 0.192 KJ mol-1 K-1 for Cd(II), suggesting increased disorder. The change in Gibbs free energy ranges from -32.66 to -29.60 KJ mol-1 for methyl orange and -32.29 to -35.99 KJ mol-1 for Cd(II), demonstrating that both adsorption processes are spontaneous. These results indicate that the adsorbent has potential as a dual-adsorption material for water remediation applications.

Investigation of adsorption properties of Periostracum serpentis as keratin-containing natural biowaste composite material for uranium

In this study, the interaction of waste snake skin (Periostracum serpentis), a keratin-based biowaste composite material, with uranyl ions, the predominant form of uranium in aqueous solutions, was investigated to determine whether it could be used as an adsorbent. SEM, FTIR, BET and EDX analyses were performed to elucidate the material's surface and structural properties. The effects of the amount of adsorbent, uranyl ion concentration, pH, temperature, and adsorption time were investigated to optimize uranium removal with this material. The results showed an adsorption capacity of 0.377 molkg-1. It was observed that the Elovich model determined the adsorption kinetics and the adsorption pH was maximum at approximately 4-5. It was found that adsorption was heat consuming, with increased orderliness and a spontaneous process. These results revealed that Periostracum serpentis, a waste material, is a potential adsorbent for removing and enriching uranium.

Insight into selective removal of trace thallium (Tl(Ι)) by novel chitosan adsorbents encapsulating low-cost silicate mineral wastes

Recently, thallium (Tl) contamination at trace levels has gained worldwide attention, particularly in the remote ore-smelting regions of China. To effectively eliminate the residual target Tl(I) ions, one of the best strategies is to develop novel adsorbents with high selectivity. In this study, we selected silicate mineral waste (SMW) and chitosan (CTS) to synthesize a low-cost composite adsorbent for the removal of trace Tl(I). The results show that a mass ratio for SMW to CTS was optimized as 3:1 (denoted as SMW@CTS), and the preferred SMW@CTS exhibited a 37% higher removal efficiency compared to pure CTS beads (19%), underscoring the critical role of SMW in enhancing trace-level adsorption of Tl(I). Under the optimal conditions of 25°C, pH = 5, and 6 g/L dosage, SMW@CTS achieved a Tl(I) removal efficiency of approx. 89% for an initial concentration of 100 μg/L. Moreover, the thermodynamics for the adsorption of Tl(I) onto SMW@CTS were investigated, and the structural characteristics of SMW@CTS were also characterized in detail. Furthermore, the mechanism for the high selectivity of Tl(I) onto SMW@CTS has been explored in the presence of humic acid and a series of competing ions. These findings highlight the novel SMW@CTS as a promising candidate for eliminating trace-level Tl(I) contamination from co-existing substances.

Dual cross-linked magnetic gelatin/carboxymethyl cellulose cryogels for enhanced Congo red adsorption: Experimental studies and machine learning modelling

To achieve highly efficient and environmentally degradable adsorbents for Congo red (CR) removal, we synthesized a dual-network nanocomposite cryogel composed of gelatin/carboxymethyl cellulose, loaded with Fe3O4 nanoparticles. Gelatin and sodium carboxymethylcellulose were cross-linked using transglutaminase and calcium chloride, respectively. The cross-linking process enhanced the thermal stability of the composite cryogels. The CR adsorption process exhibited a better fit to the pseudo-second-order model and Langmuir model, with maximum adsorption capacity of 698.19 mg/g at pH of 7, temperature of 318 K, and initial CR concentration of 500 mg/L. Thermodynamic results indicated that the CR adsorption process was both spontaneous and endothermic. The performance of machine learning model showed that the Extreme Gradient Boosting model had the highest test determination coefficient (R2 = 0.9862) and the lowest root mean square error (RMSE = 10.3901 mg/g) among the 6 models. Feature importance analysis using SHapley Additive exPlanations (SHAP) revealed that the initial concentration had the greatest influence on the model's prediction of adsorption capacity. Density functional theory calculations indicated that there were active sites on the CR molecule that can undergo electrostatic interactions with the adsorbent. Thus, the synthesized cryogels demonstrate promising potential as adsorbents for dye removal from wastewater.

Biosorption of rhodamine B and sunset yellow dyes on cross-linked chitosan-alginate biocomposite beads: Experimental and theoretical studies

This research explores the biosorption of Rhodamine B (Rd-B) and Sunset Yellow (SY) dyes using cross-linked chitosan-alginate (Ch-A) biocomposite beads, combining experimental investigations with theoretical studies to elucidate the biosorption mechanisms. The biocomposite beads were synthesized through an eco-friendly cross-linking method, and their structural properties were characterized using various characterization techniques. Complementary theoretical studies using Monte Carlo (MC) simulations and molecular dynamics (MD) calculations provided insights into the molecular interactions between the dyes and the biocomposite beads. Ch-A maximal biosorption capacity for Rd-B and SY was determined using the Langmuir model to be 43.6 mg g-1 and 25.1 mg g-1, respectively. Kinetic analysis elucidated that the biosorption process for Rd-B followed the pseudo first order (PFO) model and SY followed the pseudo second order (PSO) model. According to the thermodynamic characteristics, Rd-B and SY adsorb spontaneously and endothermically on Ch-A. In conjunction, MC and MD calculations were applied to probe the interactions between Rd-B and SY molecules and the Ch-A biocomposite beads, providing compelling evidence of robust binding interactions such as hydrogen bonds, electrostatic attractions, and π-π interactions. These theoretical insights were subsequently aligned with empirical observations, affirming a significant relation between the theoretical and experimental data. This study highlights the significance of combining experimental data with theoretical models to advance the development of environmentally friendly materials for water purification.

Deep eutectic solvent-modified polyvinyl alcohol/chitosan thin film membrane for dye adsorption: Machine learning modeling, experimental, and density functional theory calculations

The polyvinyl alcohol/chitosan (PVA/CS) thin film membrane was modified using a deep eutectic solvent (DES) to enhance its adsorption capability and mechanical strength for the removal of brilliant green (BG) dye. Batch adsorption experiments, machine learning (ML) modeling, and density functional theory (DFT) analyses were performed to evaluate the adsorption of BG using PVA/CS and DES-modified PVA/CS (DES/PVA/CS) membranes. Incorporating DES (5 wt%) into the PVA/CS membrane increased its elongation at break from 8.176 % to 22.817 %. The random forest ML model exhibited superior predictive accuracy (R2 = 0.93) compared to the artificial neural network (R2 = 0.68) for modeling the adsorption process. The adsorption experiments were conducted under optimal operating conditions for PVA/CS (pH 7.5, adsorbent mass 0.06 g, and initial BG concentration 65 mg/L) and DES/PVA/CS (pH 8, adsorbent mass 0.06 g, and initial BG concentration 80 mg/L), achieving maximum adsorption capacities of 23.15 mg/g for PVA/CS and 124.63 mg/g for DES/PVA/CS. DFT calculations showed adsorption energies of -20.76 kcal/mol and -23.13 kcal/mol for BG/PVA/CS and BG/DES/PVA/CS complexes, respectively. DES, a green modifier, significantly enhanced the adsorption capacity, mechanical stability, and functional group diversity of PVA/CS membranes, thereby enabling more efficient dye removal.

Construction of a recyclable magnetic chitosan/AlOOH/PEI composite with hierarchical porous structure for enhanced adsorption of fluoride ions from wastewater

Al(III)-based adsorbents have a strong affinity for F-, but suffer from problems such as poor structural stability, easy decomposition, and recycling difficulties in the powdered form. Herein, for the efficient removal of F- from wastewater, magnetic chitosan/AlOOH/polyethyleneimine (MCAlP) adsorbents with a hierarchical porous structure, multifunctional groups, and structural stability were constructed through chelation, cross-linking, and immobilization strategies using chitosan as a carrier. The adsorption capacity of MCAlP for F- was found to be 14.9 mg g-1 (59.8 %) greater than that of AlOOH, and the adsorption equilibrium time was reduced by 120 min. The adsorption of F- by MCAlP was better represented by the pseudo-second-order and Langmuir isothermal models (qm = 126.4 mg g-1 for F-). Chitosan, as a carrier, improved the structural stability of AlOOH, whereas the hierarchical porous structure and polyethyleneimine groups of MCAlP shortened the adsorption equilibrium time. Furthermore, MCAlP showed excellent adsorption capability, where the concentration of F- in actual wastewater was reduced from 10.1 to 1.2 mg L-1 in 10 min. Coexisting ions in fluoridated wastewater had no significant effect on the adsorption of F- by MCAlP. The main mechanisms of F- adsorption on MCAlP were found to be ion exchange, electrostatic interaction, and surface complexation.

Assessment of cerium adsorption potential of phosphoric acid activated biochar in aqueous system: Modelling and mechanistic insights

Cerium pollution in waterbodies by improper industrial waste disposal is a major concern due to its detrimental impacts on the environment. Therefore, treatment of cerium-contaminated water is inevitable. Hence, this study is focused on the remediation of cerium pollution using phosphoric acid-activated biochar (PPMB) as an adsorbent, synthesized upon pyrolytic activation of palmyra palm male flower-based pristine biochar (PMFB) with H3PO4 at 500 °C. The physico-chemical surface properties of PMFB and PPMB were evaluated through various microscopic and spectroscopic analyses. The key parameters such as biochar dosage, pH, temperature, contact time and initial cerium concentration were optimized as 0.5 g/L, 5.0, 303 K, 180 min and 50 mg/L respectively via batch adsorption. Pseudo-second order kinetic and Toth isotherm are the best-fitted models. The thermodynamic parameters including ΔG◦ (-30.4707 ± 0.7618 kJ/mol at 303 K), ΔH◦ (16.1499 ± 0.78 kJ/mol), and ΔS◦ (153.617 ± 3.8404 J/mol/K) conveying that cerium adsorption onto PPMB was spontaneous, endothermic, and highly disordered at PPMB-bulk adsorption medium interface. Precipitation, electrostatic attraction, and surface complexation are predicted to be the predominant mechanisms for the chosen PPMB-cerium adsorption system. Moreover, cerium phytotoxicity on Vigna radiata explains the real-time applicability and feasibility of cerium adsorption using PPMB. Thus, the key findings of this study specified that the higher adsorption capacity of PPMB (141.3484 ± 6.9856 mg/g) contributed by the incorporated phosphate groups, predominant mesoporosity, SSABET of 230.559 m2/g and anionic surface at a wider pH range (pH>3.08) make PPMB as efficient, economically feasible and environmentally friendly adsorbent for cerium adsorption in aqueous system.

Effective removal of Congo red and hexavalent chromium from aqueous solutions by guar gum/sodium alginate/Mg/Al-layered double hydroxide composite microspheres

In this paper, Mg/Al-layered double hydroxide (Mg/Al-LDH) was modified with the natural polymers sodium alginate and guar gum, and the prepared GG/SA/Mg-Al-LDH composite microsphere adsorbent (G-LDH) showed better adsorption performance for Congo red and hexavalent chromium in aqueous solution than the Mg/Al-LDH. The SEM image of G-LDH shows a distinct micro-spherical morphology, and it can maintain the micro-spherical morphology even after adsorbing Congo Red and hexavalent chromium. G-LDH showed strong adsorption properties for CR (Congo red) and Cr (VI) solutions with initial concentrations of 80 mg L-1 and 100 mg L-1, with adsorption amounts of 361.6 mg g-1 and 461.7 mg g-1. The unique layered structure of Mg/Al-LDH made an indispensable contribution to the efficient adsorption capacity of G-LDH when GG was used to prepare composite microspheres. The adsorption process of G-LDH is consistent with the Langmuir isotherm model and the proposed secondary kinetic model as a heat-absorbing, spontaneous, monolayer, and chemisorption process. G-LDH is an innovative anion adsorbent with excellent adsorption performance at low cost, using natural polymer materials as the backbone and the layered structure of magnesium‑aluminum hydrotalcite as the support.

A novel oxidized hierarchical porous carbon with vesicule-like ultrathin graphitic walls for efficient removal of anionic and cationic dyes

This work developed a novel oxidized hierarchical porous carbon (OHPC) with vesicule-like ultrathin graphitic walls via a method of air oxidation and used as an efficient adsorbent for Congo red (CR) and Malachite green (MG) removal. Results show that the OHPC2 oxidized at 400 °C possesses three-dimensional hierarchical pores with vesicule-like ultrathin graphitic walls. The prepared OHPC2 not only has a large specific surface area of 1020 m2 g-1 with a high pore volume, but also has abundant oxygen-containing functional groups. These unique structural features endow the OHPC2 with high adsorption capacities for CR (2729.5 mg g-1) and MG (1697.3 mg g-1) removal. The adsorption processes of CR and MG are in accordance with the Langmuir isotherm and Quasi-second-order kinetic models. The thermodynamic studies illustrate that the adsorption processes were thermodynamically feasible and spontaneous. Various characterization analysis explained that the adsorption mechanism may involve pore-filling effect, π-π conjugation, hydrogen bonding, and electrostatic attraction. Moreover, the OHPC2 exhibits good cycling stability and is identified as a desirable adsorbent for actual wastewater treatment.

Magnetic Composite Carbon from Microcrystalline Cellulose to Tackle Paracetamol Contamination: Kinetics, Mass Transfer, Equilibrium, and Thermodynamic Studies

This study reported a one-spot preparation of magnetic composite carbon (MCC@Fe) from microcrystalline cellulose (MC). The pure cellulose was impregnated in iron (III) chloride solution and carbonized at 650 °C. The MCC@Fe composite adsorbent underwent various characterization techniques. XRD identified nanostructured Fe3O4 particles with an average crystallite size of 34.3 nm embedded in the core subunits of the material. FESEM images indicated a rough and irregular surface, with some cavities along its surface, incorporating Fe3O4 nanoparticles, while EDS analysis confirmed the presence of elements like Fe, C, and O. Notably, combining thermal and chemical treatments produces a composite with more pores and a high specific surface area (500.0 m2 g-1) compared to MC (1.5 m2/g). VSM analysis confirmed the magnetic properties (0.76 emu/g), while the Hydrophobic Index (HI) showed that MCC@Fe was hydrophobic (HI 1.395). The adsorption studies consisted of kinetic, mass transfer, equilibrium, and thermodynamics studies. Kinetic study of the adsorption of paracetamol on MCC@Fe composite proved to be rapid, and the time necessary for covering 95% of the surface (t0.95) was lower than 27 min following the fractal-like pseudo-first-order model (FPFO). Liu's isotherm proved to be the most appropriate for understanding the adsorption equilibrium. Remarkably, the maximum sorption capacity (Qmax) of paracetamol was 34.78 mg g-1 at 45 °C. The ΔH° value (+27.00 kJ/mol) and the negative ΔG° values were consistent with the physisorption mechanism and favorable process. Furthermore, the mass transfer mechanism showed that the transfer is governed by the intraparticle diffusion model, with surface diffusion being the rate-limiting step when considering the Biot number greater than 100. This research displayed a single-route production of inexpensive magnetic nano adsorbents capable of efficiently eliminating paracetamol from aqueous environments.

Color Compounds Removal from Tequila Vinasses Using Silica Gel Adsorbents Functionalized with Thiol Moieties: Equilibrium and Kinetics Studies

Tequila vinasses are organic wastes generated during ethanol fermentation at elevated temperatures (≥90 °C) and pH ≤ 4.0, making them hazardous to the environment. This paper describes a new, simplified UV-vis spectroscopy-based procedure for monitoring the adsorption of color compounds in tequila vinasses onto silica-based adsorbents, along with an optimized synthesis method to produce the most efficient sol-gel synthesized thiol-functionalized adsorbent. Under optimized conditions, the uptake capacity of this adsorbent reaches 0.8 g g-1 in 90 min. Experimental results demonstrate that the adsorbent has a specific affinity for melanoidin-type molecules. The adsorbent demonstrates excellent thermal stability (~316 °C). The results of this work indicate that the adsorbent possesses potential in the treatment of tequila vinasses from wastewater discharges.

Tripolyphosphate-functionalized cellulose: A green solution for cadmium contamination

This study introduces a highly efficient tripolyphosphate -tethered cellulose sorbent for cadmium (Cd2⁺) removal from aqueous solutions. Characterization through FTIR and SEM revealed the material's structural properties. The sorbent achieved 99% Cd2⁺ removal even at a minimal dosage of 0.05 g. Optimal sorption occurred within the pH range of 4-6, influenced by the sorbent's weak acidic functional groups. Rapid kinetics, reaching equilibrium within a minute, and a high sorption capacity (up to 18.03 mg/g at 50 °C) were observed. Langmuir isotherm modeling confirmed monolayer sorption, and thermodynamic studies indicated a spontaneous, endothermic process with increased randomness at the solid-liquid interface. Selectivity studies demonstrated strong Cd2⁺ removal performance in the presence of competing ions, with minimal interference from monovalent ions but notable effects from divalent ions. The sorbent exhibited consistent reusability over multiple cycles. XPS analysis conclusively established an ion exchange mechanism between Cd2⁺ and negatively charged P3O105- groups as the primary removal pathway. This research highlights the potential of TPP-tethered cellulose as a promising sorbent for effective Cd2⁺ remediation.

Removal of Ciprofloxacin and Norfloxacin from Aqueous Solution with Activated Carbon from Cupuaçu (Theobroma grandiflorum) Bark

The widespread use of antibiotics such as fluoroquinolones (FQs) has raised environmental and health concerns. This study is innovative as we investigate the removal of ciprofloxacin (CIP) and norfloxacin (NOR) from water using activated carbon derived from cupuaçu bark (CAC). This previously discarded biomass is now a low-cost raw material for the production of activated carbon, boosting the local economy. CAC was physiochemically characterized, and adsorption experiments were designed using the Box-Behnken design to assess the effects of contact time, adsorbate concentration, and adsorbent dosage on the removal efficiency and adsorption capacity. The optimal conditions were determined using the desirability function, and kinetic, isothermal, and thermodynamic experiments were performed. CAC showed a 50.22% yield, low humidity (4.81%), and low ash content (4.27%), with acidic functional groups dominating. The surface area was 1335.66 m2/g, with an average pore volume of 0.753 cm3/g and a pore diameter of 2.206 nm. Adsorption was most effective at pH 5.0 due to electrostatic interactions between the basic adsorbent and cationic forms of CIP and NOR. Optimal conditions yielded adsorption capacities of 6.02 mg/g for CIP and 5.70 mg/g for NOR, with the Langmuir model suggesting monolayer adsorption. The regeneration with NaOH was effective, but the adsorption efficiency decreased below 50% after two cycles. These findings demonstrate that CAC is a sustainable, low-cost adsorbent for treating antibiotic-contaminated water.

The adsorption of chlorpyrifos and malathion under environmentally relevant conditions using biowaste carbon materials

Water bodies face persistent contamination from organophosphorus pesticides like chlorpyrifos and malathion, which pose substantial environmental and health hazards due to their toxicity and resilience in ecosystems. This study explores the potential of spent coffee grounds, a common agricultural byproduct, as an eco-friendly adsorbent for eliminating these pesticides from polluted water. Spent coffee grounds underwent carbonization at 400 °C and various activation treatments using KOH, H3PO4, CO2, and their combinations. The impact of these activation methods on the adsorption capacity of carbonized materials was assessed under environmentally relevant conditions (25 °C, pH=6, and typical pesticide concentrations in wastewater). Results revealed that the physical and chemical properties of biowaste-derived materials significantly influence their adsorption efficiency, with KOH-activated adsorbents exhibiting the highest capacities ((16.1 ± 0.8) mg g-1 for chlorpyrifos and (11.2 ± 0.2) mg g-1 for malathion). Spent coffee grounds carbonized at 400 °C without additional activation demonstrated similar adsorption performance to the best-performing material ((19.4 ± 0.4) mg g-1 for chlorpyrifos and (10.6 ± 0.4) mg g-1 for malathion), with notably lower economic and environmental costs. Given its straightforward preparation and significant adsorption capacity, this material stands out as a sustainable solution for treating agrochemical wastewater containing chlorpyrifos and malathion.

Cationic waste hemp fibers-based membrane: Case study of anionic pollutants removal through environmentally friendly processes

In this study, waste hemp fibers were transformed into cationically modified lignocellulosic adsorbent through a three-step process. First, a delignification/defibrillation pretreatment was performed, followed by quaternization of fibers using the synthesized ionic liquid chlorocholine chloride-urea (CCC-U). Pressure-assisted cross-linking of modified fibres, using a citric acid, produced new membrane (CCC-UHM). The removal of anionic dyes (Acid Yellow 36 (AY36), Congo Red (CR), Acid Green 25 (AG25), and Acid Blue 92 (AB92)), and oxyanions (As(V) and Cr(VI)) was tested in batch and column system. The structural characteristics and chemical properties of the syntesised materials were investigated by SEM, FTIR, Raman, XPS, XRD, specific density, porosity and point of zero charges analysis. The endothermic and spontaneous equilibration of the system resulted in high capacity (qm), i.e., 302.9 mg g-1 (AY36), 456.8 mg g-1 (CR), 812.8 mg g-1 (AG25), 587.6 mg g-1 (AB92), 107.9 mg g-1 (As(V)), and 67.84 mg g-1 (Cr(VI)) at 25 °C, using the Langmuir model. The optimum pH for the adsorption process was 7. The multi-cycle adsorption/desorption process was followed by either decolorization, using laccase from M. thermophile expressed in Aspergillus oryzae (Novozym 51,003® laccase) immobilized on amino-modified fibers as biocatalyst, or photocatalytic degradation, in the presence of zinc oxide. The high decolorization efficiency (96%) observed for AG25 and AB92 underscores the considerable potential of laccase immobilized preparations as sustainable and eco-friendly approach for treating dye-contaminated wastewater. Photodegradation process provided low environmental threat of processed water, and biodegradabilty of exhausted membrane confirmed the circularity of the developed technology with implemented principles of sustainability.

Insights into kinetic, isotherm, and thermodynamic of ultrasound mode- and amplitude-dependent carotenoid and chlorophyll degradation or/and adsorption

Experimental data were analyzed to investigate the underlying adsorption or degradation mechanism of carotenoids and chlorophylls over the bleaching of sunflower oil through different amplitudes of horn and bath ultrasound (ultrasound-assisted bleaching; UAB), temperature, time, and bleaching clay. Quantifying the color removal efficiency in both batch and continuous systems, along with the corresponding process time and energy consumption, is paramount for evaluating the energy-related performance of the treatment method. The adsorption of pigments onto activated bentonite was notably rapid and effective when ultrasound was employed. In both bleaching processes, the adsorption kinetics of carotenoids and chlorophyll exhibited a pseudo-second-order behavior. At the same time, a pseudo-first-order equation provided a better fit for the control conditions. Moreover, intra-particle diffusion contributed to the adsorption mechanism, although it was not the only rate-limiting step in the adsorption of pigments on the clay. It is hypothesized that carotenoid and chlorophyll adsorption occur through physisorption in control conditions, while chemical reactions play a role in pigment removal under sonication. The Freundlich isotherm yielded precise estimates of the adsorption equilibrium data for carotenoid and chlorophyll during ultrasonic bleaching, suggesting a multilayer adsorption mechanism under ultrasound exposure. The thermodynamic study found that pigment adsorption was feasible, spontaneous, and endothermic. According to the results, horn and bath ultrasound, especially at higher voltages, can remarkably remove carotenoid and chlorophyll from sunflower oil compared to the traditional bleaching process.

Adsorption and removal of Pb (II) via layer double hydroxide encapsulated with chitosan; synthesis, characterization adsorption isotherms, kinetics, thermodynamics, & optimization via Box-Behnken design

The study aimed to enhance the stability and efficiency of removing bivalent Pb(II) by encapsulating AlNi-layered double hydroxide (LDH) in chitosan and itaconic acid to create an adsorbent with chemically active sites. The resulting material, AlNi-LDH/CS, underwent thorough property analysis using XRD, FT-IR, XPS, EDX, N2 adsorption/desorption isotherm, and FESEM to find out what textural characteristics it has. Specifically, nitrogen adsorption/desorption isotherms were utilized to assess the textural properties of AlNi-LDH/CS. The Al/Ni-LDH/CS surface displayed a specific surface area of 71.95 m2/g and an average pore size of 2.537 nm, consistent with the platelets' external surface. The effects of dose, pH, temperature, and starting concentration on the adsorption process were also investigated in this study. The adsorption characteristics have been examined by means of equilibrium and adsorption kinetics. The adsorption process adhered to the pseudo-second-order and Langmuir isotherm models. The predominant adsorption process was found to be chemisorption, which had an adsorption energy of 28.42 kJ·mol-1. An endothermic and spontaneous adsorption process is suggested by the increase in metal absorption at increasing temperatures. The Box-Behnken design software was utilized to establish the optimal adsorption parameters as pH 5, a dosage of 0.2 g of AlNi-LDH/CS per 25 mL, and an adsorption capacity of 453.05 mg/g for the Pb(II) arsenate solution. For the composite sponge to be most effective in adsorbing arsenate and be used in water purification procedures, these factors are essential. The adsorption process was successfully improved with few planned tests by applying the Box-Behnken design and response surface technique aspects of the Design-Expert software. An evaluation of the adsorbent's reusability using six successive cycles of adsorption and desorption confirmed its stability and showed no discernible decrease in removal efficiency. Additionally, it retained its original chemical composition before and after reuse, showcased consistent efficiency, and maintained uniform XRD data.

Green preparation of polydopamine-modified multiwalled carbon nanotube/calcium alginate composite aerogels for effective adsorption of methylene blue

Polydopamine-modified multiwalled carbon nanotube/calcium alginate (P-CNTs/CA) aerogel was greenly prepared. The synthesis method of the P-CNTs/CA aerogel was evaluated for its environmental friendliness. SEM, FT-IR, Raman, TGA, BET, XPS, and Zeta potential characterized the P-CNTs/CA aerogel. Batch adsorption experiments were conducted to assess the adsorption efficacy of the P-CNTs/CA aerogel on methylene blue (MB). The results demonstrated that the maximum theoretical adsorption capacity of the P-CNTs/CA aerogel for MB was 506.12 mg‧g-1. The adsorption kinetics analysis indicated that the adsorption of MB by the P-CNTs/CA aerogel was more consistent with the pseudo-second-order model. The adsorption isotherm analysis demonstrated that the Sips model exhibited the most accurate fit to the experimental data. The adsorption thermodynamics showed that the adsorption process was spontaneous and heat-absorbing. The adsorption mechanism of MB adsorption by P-CNTs/CA aerogel was analyzed graphically by the density functional theory (DFT) and independent gradient model (IGM), which revealed the involvement of hydrogen bonding, electrostatic, and dispersive interactions. In parallel, the distribution of adsorption forces was analyzed using isosurfaces. Adsorption desorption experiment showed that the P-CNTs/CA aerogel maintained 79 % removal capacity after six adsorption cycles.

Single and combined treatment processes for rhodamine B removal by coagulation-flocculation and adsorption

In this paper, two physico-chemical methods were adopted for the removal of rhodamine B from aqueous solutions. The first one is the adsorption process using biochar derived from olive stones (OSB). Results demonstrated that the removal efficiency reached 97.79% within an equilibrium time of one hour. It was observed that the pH had no significant effect on the degradation of rhodamine B by OSB. The adsorption process was characterized by the endothermic nature, spontaneity, favorability, and disorder at the solid-liquid interface. Langmuir isotherm analysis revealed a maximum adsorption capacity of 11.82 mg g-1, and the prepared biochar could be reused for up to four cycles. For the second method, coagulation-flocculation using FeCl3 as a coagulant was investigated. The findings displayed that an increase in the dosage of FeCl3 enhanced the degradation process, with the best performance registered at a dose of 2000 mg L-1 of FeCl3. The optimum pH for this process was found to be 2. A combination approach by these two methods, starting with coagulation-flocculation and followed by adsorption, was also investigated. The results showed that the combined approach improved the removal performance compared to each process alone, with minimal doses of both coagulant and adsorbent. Thus, the combination of these two physico-chemical processes allows benefits from the advantages and reduces the disadvantages of each individual method.

Development of Variable Charge Cationic Hydrogel Particles with Potential Application in the Removal of Amoxicillin and Sulfamethoxazole from Water

Cationic hydrogel particles (CHPs) crosslinked with glutaraldehyde were synthesized and characterized to evaluate their removal capacity for two globally consumed antibiotics: amoxicillin and sulfamethoxazole. The obtained material was characterized by FTIR, SEM, and TGA, confirming effective crosslinking. The optimal working pH was determined to be 6.0 for amoxicillin and 4.0 for sulfamethoxazole. Under these conditions, the CHPs achieved over 90.0% removal of amoxicillin after 360 min at room temperature, while sulfamethoxazole removal reached approximately 60.0% after 300 min. Thermodynamic analysis indicated that adsorption occurs through a physisorption process and is endothermic. The ΔH° values of 28.38 kJ mol-1, 12.39 kJ mol-1, and ΔS° 97.19 J mol-1 K-1, and 33.94 J mol-1 K-1 for AMX and SMX, respectively. These results highlight the potential of CHPs as promising materials for the removal of such contaminants from aqueous media.

Adsorption behavior of cationic dyes on starch nanocrystals: Kinetic, isotherm, and thermodynamic insights from single to multi-component systems

The adsorptive potential of starch nanocrystals (SNCs) was evaluated for the elimination of methylene blue (MB), crystal violet (CV), and malachite green (MG) from aqueous media in single, binary, and ternary dye systems using batch mode experiments. SNCs were extracted using mild acid hydrolysis to remove the amorphous parts of native granular starch, and they were characterized using different physicochemical methods, such as FESEM, XRD, FTIR, BET, TGA, and pHZPC. The results revealed that the optimal pH for dye removal in both single and mixed dye systems was found to be 9.0. The equilibrium time increased from 5 to 20 min when the system was changed from single to binary, and then further increased to 30 min when the system was changed to ternary. The equilibrium data for single-dye systems exhibited a good fit with the Langmuir isotherm model (R2 > 0.98, SEE <3.52 mg g-1), whereas for binary and ternary dye mixtures, the extended Langmuir model provided an accurate representation of the experimental data (R2 > 0.99, SEE <1.33 mg g-1). Among the single, binary, and ternary systems, the highest adsorption capacities were observed for MB, MB in the (MB + MG) binary system, and MB in the (MB + CV + MG) ternary system. The respective adsorption capacities were recorded as 79.55 mg g-1, 61.91 mg g-1, and 43.59 mg g-1. The adsorption of dyes onto the SNCs was inherently spontaneous and endothermic, and adhered to the pseudo-second-order kinetic model in single dye systems as well as mixed dye systems. It can be concluded that the SNCs are capable of being utilized for five consecutive cycles in the adsorption-desorption process for single dye systems and three consecutive cycles for mixed dye systems. This suggests that the SNCs have potential as a sustainable and efficient option for dye removal in mixture systems.

Sorption thermodynamic and kinetic study of Cu(II) onto modified plant stem bark

In this study, four types of "Juá" stem barks (Ziziphus joazeiro) were investigated for the removal of Cu(II) from aqueous solutions. The tested samples included natural coarse barks, and barks washed with water, ethanol-water, and NaOH solutions. The solvent-modified materials simulated the waste of the industrial extraction of saponins from bark. The valorization of these processing residues as sorbents was evaluated. The NaOH-washed sorbent exhibited the highest sorption capacity for Cu(II) (maximum sorption capacity ≈ 32 mg g-1). Ion exchange process between copper and exchangeable surface cations and electrostatic attraction of copper with carboxylate and phenolate groups were identified as the primary sorption mechanisms. Desorption tests revealed that a large portion of the metal sorbed (80%) was easily released from the sorbent thus suggesting, in line with the proposed mechanisms, the existence of weak sorbate-sorbent interactions. The sorptive process was found to be exothermic (∆H° =  - 48.1 ± 13.5 kJ.mol-1) and thermodynamically favorable at lower temperatures.

New insights into the remediation of chromium-contaminated industrial electroplating wastewater by an innovative nano-modified biochar derived from spent mushroom substrate: Mechanisms, batch study, stability and application

To enhance the adsorption and detoxification capabilities of hexavalent chromium (Cr(VI)) using agricultural spent mushroom substrate (SMS), this study pioneered the preparation of biochar (NBC) from Lentinus edodes spent substrate. Subsequently, nano iron sulfide (FeS) particles were integrated onto NBC with carboxymethyl cellulose (CMC) as a stabilizer, resulting in a novel composite biosorption material, nFeS-BC. The adsorption and reduction potential of both NBC and nFeS-BC against Cr(VI) were evaluated through batch experiments, which identified pH as a critical factor influencing adsorption efficiency. Remarkably, nFeS-BC exhibited a superior maximum adsorption capacity (qmax) of 99.57 mg g-1 and a reduction efficiency of 68.65%, outperforming NBC by 277.73% and 211.76% under optimized conditions, respectively. Characterization techniques including Scanning Electron Microscopy-Energy Dispersive X-Ray (SEM-EDX), Fourier Transform Infrared Spectroscopy (FT-IR), and X-ray Photoelectron Spectroscopy (XPS) elucidated the removal mechanisms, predominantly attributed to ion exchange, electrostatic attraction, functional group interaction, and redox reaction. The carbon-oxygen functional groups and nano particles were crucial in the adsorption and reduction processes. Compared with NBC, the incorporation of FeS particles increased the specific surface area and pore volume of nFeS-BC by 130.86% and 183.77%, respectively. nFeS-BC owned a shelf-life of up to ∼3 months of use and exhibited excellent performance in the processing of actual electroplating wastewater with q of 16.71 mg g-1 under 0.1 g L-1 dosage. These findings underscore the potential of nFeS-BC as an efficient material for Cr(VI) removal, presenting a novel adsorbent for the sustainable detoxification of contaminated water resources and the potential for using agricultural waste materials in environmental remediation.

Honeycomb-like macroporous crosslinked chitosan assisted EDTA-intercalated Ca-Mg-Al layered hydrotalcite composite foams for efficient U(VI) biosorption

The biosorption is considered to be highly efficient for the separation of radionuclide from radioactive wastewater. Herein, the crosslinked chitosan assisted EDTA intercalated Ca-Mg-Al layered double hydroxides composite foam (CS-EDTA-LDH) was synthesized by combining EDTA intercalation and freeze-drying methods. The macroporous and ultralight properties of CS-EDTA-LDH facilitates its rapid adsorption and facile recovery, and the inorganic/organic incorporation can avoid pore collapse and provide numerous adsorption sites, while the EDTA intercalation can enhance the complex capture of U(VI). The CS-EDTA-LDH presents various functional groups (carboxyl, hydroxyl and amino groups) for U(VI) adsorption, and the adsorption capacity for U(VI) reached 272.3 mg/g at pH 5.0 and 298 K. The adsorption kinetics of U(VI) conformed to PSO equation, whereas the isotherms conformed to the Freundlich model, indicating heterogeneous adsorption with diffusion process as a rate-controlling step. The thermodynamic parameters indicate that U(VI) adsorption by CS-EDTA-LDH is endothermic and spontaneous in nature. The adsorption mechanism is related to the synergic complexation by multi-functional groups, ion exchange, and possible isomeric substitution. Overall, CS-EDTA-LDH could be a promising biosorbent for the cleanup of radioactive pollution due to its high performance for U(VI) adsorption and facile recovery.

Fluorescent cellulose hydrogels based on corn stalk of double sulfhydryl functional group modification for Hg(II) removal and detection

Ions of mercury, one of the most hazardous heavy metals in nature, pose serious risks to the environment and human health. Blue sulfur-doped carbon dots (SCDs) from corn stalks were utilized as material. The SCDs were incorporated into a carboxylated hydrogel modified with sulfur, and a compound gel (SCDs-KTOCS gel) was successfully fabricated for simultaneous fluorescence detection and Hg(II) adsorption. This enabled the effective identification and removal of Hg(II) from contaminated water. The chemical content, fluorescence properties, and adsorption behaviors of the SCDs-KTOCS-gels were analyzed. The results demonstrate that the SCDs-KTOCS-gels exhibited effective Hg(II) adsorption (193 mg/g) and an extensive linear spectrum for Hg(II) fluorescence emission (150-500 mg/L; detection limit = 1.5668 mg/L). The adsorption values fit well with the Temkin models and pseudo-second-order kinetics. Additionally, Hg(II) detection and adsorption in the SCDs-KTOCS-gels were examined. By exchanging the existing probe for a suitable one that fits various relevant applications, this study suggests an environmentally friendly and sustainable method of producing materials for removing and detecting Hg(II) and constructing a fluorescence hydrogel for the detection and adsorption of different metals.

Preparation and characterization of oat hulls-filled-sodium alginate biocomposite microbeads for the effective adsorption of toxic methylene blue dye

In this work, the performance of oat hull-filled sodium alginate (SA-O) biocomposite microbeads in the adsorptive removal of methylene blue (MB) dye was examined. First, oat hulls were pulverized and biocomposite gels containing different weight ratios of oat hulls (10 %, 20 %, and 30 %, concerning the SA amount) were prepared by dispersing them in SA solution by ultrasonic homogenization method. Finally, gels were cross-linked by dropping into a 2 % CaCl2 solution. The study revealed that the optimal adsorbent dosage was 0.025 g/50 mL, pH was roughly 6-8, and the contact time was 120 min. According to isotherm models, the non-linear Sips and Langmuir model was more appropriate compare to other isotherms from error analysis, with a maximum adsorption capacity of 687.65 mg/g and 757.57 mg/g at 298 K, respectively. Furthermore, the non-linear kinetic data and error analyzes demonstrated that the process followed the pseudo-second-order kinetic. The adsorption process was exothermic (∆H°=-17.71 kJ/mol) and spontaneous (∆G°=-26.23 kJ/mol) at 298 K, based on thermodynamic characteristics. Furthermore, reusability investigations demonstrated that the adsorbent retained its performance with no major changes in characteristics. This work reveals that highly efficient, low-cost, sustainable, and eco-friendly SA-O composites with properties might be useful adsorbents for cationic dye adsorption.

Valorization of the performance of novel and natural sodium alginate/pectin/Portulaca oleracea L. ternary composites in the adsorption of toxic methylene blue dye from the aquatic environment

This research introduces the development of a novel, sustainable, cost-effective, and eco-friendly sodium alginate (SA)-pectin (P) ternary composite, enhanced with Portulaca oleracea L. (PO) additive, which has been thoroughly investigated for its efficacy in removing hazardous methylene blue (MB) dye from wastewater. The selectivity studies using various cationic and anionic dyes were conducted. The composite microbeads that were generated underwent characterization using FTIR-ATR, SEM, XRD, zeta potential, and pHpzc analysis. Subsequently, the most favorable parameters for adsorption, including initial pH (2-12), contact time (0-180 min), adsorbent dosage (0.01-0.20 g), and temperature (298-318 K), were identified. The effect of monovalent and divalent salt concentrations on adsorption process was evaluated. The adsorption data were utilized in several isotherm (Langmuir, Freundlich, D-R, and Temkin) and kinetic (pseudo-first-order and pseudo-second-order) models. According to the Langmuir isotherm model was calculated the adsorption capacity at 298 K is 709.22 mg/g for SA/P/PO30 composite microbeads. The process of adsorption was seen to conform to a pseudo-second-order kinetic model. The results revealed that the process was both exothermic (∆Ho=-10.42kJ/mol) and spontaneous (∆Go=-26.04kJ/molat298K). Moreover, reusability analyses demonstrated that the composite microbeads that were created may be utilized several times, even after the 5th cycle. The results indicate that the developed composite microbeads have the potential to serve as an effective and inexpensive adsorbent for eliminating cationic contaminants from a wastewater.

Carboxymethyl cellulose assisted morphology controlled synthesis of Mn3O4 nanostructures for adsorptive removal of malachite green from water

The physicochemical properties of manganese oxides and their different applications mainly depend upon their crystallite size, morphology, phase structure, and surface properties, which are again dependent on the preparation methods. So, a simple, cost-effective, and versatile synthesis method for such materials is highly desirable. Intending to accomplish this, herein we report the synthesis of Mn3O4 nanostructures by alkaline hydrolysis of the corresponding metal ions in an aqueous medium. The addition of a biodegradable polymer, sodium salt of carboxymethyl cellulose (Na-CMC) assisted the development of specific morphology, which is tunable by varying the concentration of the biopolymer. The spectroscopic, microscopic, and diffractometric analyses of the synthesized Mn3O4 nanostructures confirm that this particular simple technique is very effective in controlling the morphology of the formed nanostructures. These Mn3O4 nanostructures exhibit excellent adsorption capacity in the removal of malachite green (MG) from its aqueous solution under ambient conditions. The adsorption process is exothermic following pseudo-second-order kinetics with a maximum dye adsorption capacity of 489.68 mg g-1 according to the Sips isotherm model. The Mn3O4 nanostructures can be reused for up to five cycles of dye adsorption without significant loss of their adsorption performance.

Hydrochar as a bio-based adsorbent for heavy metals removal: A review of production processes, adsorption mechanisms, kinetic models, regeneration and reusability

The spread of heavy metals throughout the ecosystem has extremely endangered human health, animals, plants, and natural resources. Hydrochar has emerged as a promising adsorbent for removal of heavy metals from water and wastewater. Hydrochar, obtained from hydrothermal carbonization of biomass, owns unique physical and chemical properties that are highly potent in capturing heavy metals via surface complexation, electrostatic interactions, and ion exchange mechanisms. This review focuses on removing heavy metals by hydrochar adsorbents from water bodies. The article discusses factors affecting the adsorption capacity of hydrochars, such as contact time, pH, initial metal concentration, temperature, and competing ions. Literature on optimization approaches such as surface modification, composite development, and hybrid systems are reviewed to enlighten mechanisms undertaking the efficiency of hydrochars in heavy metals removal from wastewater. The review also addresses challenges such as hydrochar regeneration and reusability, alongside potential issues related to its disposal and metal leaching. Integration with current water purification methods and the significance of ongoing research and initiatives promoting hydrochar-based technologies were also outlined. The article concludes that combining hydrochar with modern technologies such as nanotechnology and advanced oxidation techniques holds promise for improving heavy metal remediation. Overall, this comprehensive analysis provides valuable insights to guide future studies and foster the development of effective, affordable, and environmentally friendly heavy metal removal technologies to ensure the attainment of safer drinking water for communities worldwide.

MIL-88A(Al)/chitosan/graphene oxide composite aerogel with hierarchical porosity for enhanced radioactive iodine adsorption

To ensure the sustainable development of the nuclear industry, the effective capture of radioiodine from nuclear wastewater has attracted much attention. Herein, a novel MIL-88A(Al)/chitosan/graphene oxide (MCG) composite aerogel was prepared by using crosslinked chitosan and graphene oxide as the 3D network skeleton, and MIL-88A(Al) nanocrystalline particles were introduced into the skeleton by freeze-drying method. MIL-88A(Al) adsorption capacities for volatile and soluble iodine were 2.02 g g-1 and 850.00 mg g-1, respectively. Owing to the synergistic effect of MIL-88A(Al), GO, CS, and the hierarchically porous structures of the MCG aerogel, the adsorption capacities for volatile and soluble iodine by the MCG aerogel were increased to 2.62 g g-1 and 1072.60 mg g-1, respectively. Furthermore, the adsorption performance of the MCG aerogel for volatile and soluble iodine could be maintained at 83 % and 82 % after 5 cycles, suggesting excellent recoverability. Meanwhile, the adsorption mechanism studies showed the interactions between iodine and NH, AlO, and CO in MCG aerogel. Furthermore, the adsorption process is consistent with the Elovich kinetic and Sips isotherm models. MCG aerogels are potential candidates for enhanced radioiodine adsorption due to their high radioiodine capture performance and excellent recyclability.

Synergy of Magnetic Nanoparticles and Sodium Alginate-Coated Lignin for Effective Pollutant Remediation, Simple Recovery, and Cost-Effective Regeneration

In the pursuit of sustainable materials for environmental remediation, this study presents the development and comprehensive characterization of cobalt ferrite nanoparticles (CFNPs) incorporated in lignocellulosic-derived sodium alginate (CFNPs@LCG-SA) biocomposite beads. These biobased beads exhibit exceptional adsorption capabilities, particularly for methylene blue (MB) dyes, rendering them promising candidates for wastewater treatment. Using a comprehensive range of analytical techniques, including Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis-derivative thermogravimetry (TGA/DTG), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), etc., we elucidated their structural, physicochemical, and thermal properties. Their multifunctional nature, derived from lignin and sodium alginate components, provides ample active sites for both physical interactions and chemical bonding with contaminants apart from the magnetic character attributed by the CFNPs. With a freeze-drying approach, the optimal adsorption capacity and removal rate of MB reached 97 mg/g and 99%, respectively, and no meaningful decline in their activity was noted even after six cycles. The CFNPs@LCG-SA biocomposite beads emerge as a cost-efficient and sustainable remedy for environmental cleanup, offering valuable perspectives in environmental preservation and advancing green energy technologies.

Brazilian bentonite/MgO composites for adsorption of cationic and anionic dyes

Industrial effluents, especially those containing dyes, have become the main cause of contamination of water resources. In this context, Brazilian bentonite/MgO composites, with excellent adsorptive properties, were prepared and investigated for their effectiveness in removing cationic and anionic dyes from aqueous solutions. The new adsorbents were obtained using Brazilian bentonites and MgO using the mechanochemical method followed by heat treatment (at 700 °C for 4 h). Different characterization techniques were used for the chemical, mineralogical, thermal, surface, and morphological analysis of the raw clays and the composites. The experimental adsorption isotherms were quantified under different conditions of initial concentration, contact time, pH, adsorbent dosage, and temperature variation to interpret the adsorption mechanism of the crystal violet (CV) and Congo red (CR) dyes. The modeling results were obtained from the empirical Sips equation and Pseudo Second Order (PSO) kinetics, indicating that the adsorption of molecules is a heterogeneous phenomenon that occurs in a monolayer on the surface (ns > 1), with the adsorption rate determined by chemisorption. The composites showed the best removal efficiency performance compared to the raw bentonites, with an increase of 12% for the CV dye and 46% for the CR dye. In addition, the qmax values obtained were 423.02 mg/g and 479.86 mg/g (AM01). This research underscores the potential of Brazilian bentonite/MgO composites as a promising solution for the removal of cationic and anionic dyes from water, offering hope for future applications in the field of environmental engineering and materials science.

Adsorption of terbium (III) on DGA and LN resins: Thermodynamics, isotherms, and kinetics

Two commercially available extraction chromatography (EXC) resins containing N,N,N',N'-tetra-n-octyldiglycolamide (DGA Resin, Normal, 50 - 100 μm) and Bis(2-ethylhexyl) phosphate (LN Resin, 100 - 150 μm) were used as adsorbents to study fundamental adsorption properties such as thermodynamic values, equilibrium isotherms, and kinetic uptake models for terbium(III) adsorption. Weight distribution ratios (Dw) for terbium on DGA and LN resins were measured using a [160Tb]Tb3+radiometric tracer in nitric acid as a function of acidity, temperature, initial analyte concentration, and equilibrium time. The Dw values showed increasing binding affinity for DGA resin at high nitric acid concentrations and decreasing binding affinity for LN resins. Thermodynamic studies for DGA and LN resins revealed that the Gibbs free energy (ΔG) increased consistently with temperature. To model equilibrium data, increasingly higher parameter equilibrium isotherm models (Henry (1) < Langmuir, Freundlich (2) < Redlich-Peterson (3) < Fritz-Schluender (4)) were compared on their root mean squared errors (RMSE) and adjusted determination coefficients to determine the most applicable model. In all cases, the empirical four-parameter Fritz-Schluender isotherm demonstrated a superior fit. Similar comparisons for reaction-based kinetic models (Pseudo-first-order < Pseudo-second-order < Pseudo-n-order) revealed that the higher-order PNO model yielded a superior fit of kinetic data for both resins. However, in some cases, adsorption isotherms and kinetic models could also be modeled by a lower-order model with minimal change in error parameters. Weber-Morris plots revealed that two linear sections are observed for each resin, where the first linear segment is attributed to fast (film diffusion) adsorption of terbium, followed by slower intraparticle diffusion of terbium through the pores as the rate-limiting step. Based on the Weber-Morris plot, both film and intraparticle diffusion are involved in controlling the kinetic rate of adsorption for DGA and LN resins.

Novel algae-chitosan/alginate beads for efficient basic Fuchsin removal: Synthesis, characterization, adsorption study, mechanism, and optimization

In this study, utilized algae activated with citric acid and lime juice to develop a novel bioadsorbent, The Algae@CS/Alginate beads were formed by encapsulating the activated algae with chitosan and alginate, producing a nanocomposite that is efficient in removing Basic Fuchsin (BF) dye from water. The beads were characterized by means of a diversity of techniques, such as FTIR, XRD, XPS, SEM and determination the surface area via N2 adsorption/desorption isotherm that permitted that the adsorbent has high surface area 124.43 m2/g. The electrical properties of the BF, including its structure and reactivity, were determined by density functional theory (DFT). The MEP data and the molecular orbitals (HOMO and LUMO), as well as the sites of the electrophilic besides nucleophilic attack places, correspond fairly well, according to DFT. The adsorption process was fitted to Langmuir isothermally, and kinetically to pseudo-second-order (PSOE) model. The adsorption mechanism was identified as chemisorption with an adsorption energy of 32.6 kJ/mol. Thermodynamic research shows that the BF adsorption process by Algae@CS/Alginate beads is spontaneous and endothermic because of the positive ΔHo and negative ΔGo. Through numerical optimization of the programmed, the ideal conditions for adsorption were strongminded to be a pH of 8, a dosage of 0.02 g/25 mL for Algae@CS/Alginate beads, and a concentration of 367.27 mg/g of BF. Using the least amount of intended experiments, the adsorption procedure was optimized by the request of Box-Behnken design (BBD) and answer surface methodology (RSM) in Design-Expert software. Adsorbent reusability test results showed that, following eight successive cycles of adsorption and desorption, the adsorbent was stable and that removal efficacy had not decreased. It additionally demonstrated good efficacy, no alteration in chemical conformation, and the same XRD and FTIR data before and after recycle. Analyze the interaction between the Algae@CS/Alginate beads and the BF.

Preparation of Magnetic Spongy Porous Carbon Skeleton Materials for Efficient Removal of BTEX

Magnetic polymer microspheres have been extensively utilized as separable and highly efficient adsorbents in wastewater treatment. In this study, a series of novel magnetic spongy porous carbon skeleton materials (Mag-SPCS) have been designed and synthesized by acetonitrile suspension precipitation polymerization, which combines the advantages of the acetonitrile precipitation method and the suspension polymerization method. It was demonstrated that the transformation of the material morphology from microspheres to a porous sponge was achieved by a gradual decrease in the usage amount of ethylene glycol. After N,N-dimethyloctadecylamine (C18) was grafted onto the Mag-SPCS materials, the C18-Mag-SPCS materials with a superhigh saturation adsorption capacity and superfast adsorption efficiency were used for the removal of BTEX (toluene, benzene, and para-xylene) in wastewater. Subsequently, the adsorption properties of the composites with different morphologies were evaluated, and the effect of the usage amount of C18 on the adsorption properties of the C18-Mag-SPCS was further investigated. The maximum adsorption capacities of C18-Mag-SPCS for benzene, toluene, and para-xylene were 714.84, 564.32, and 394.48 mg/g, respectively. The adsorption process was conducted in accordance with the proposed secondary and Langmuir models. Finally, the FTIR, XPS, and XRD characterization results before and after adsorption demonstrated that the adsorption mechanism of toluene onto C18-Mag-SPCS was primarily hydrogen bonding, π-π stacking, and van der Waals forces. These findings of the study indicate that the composite material exhibits an ultrahigh saturation adsorption capacity and ultrafast adsorption efficiency, thereby confirming its considerable potential for application in wastewater treatment.

Preparation and application of SiO2-Fe2O3 and SiO2-Fe2O3-Fe for soot oxidation: A step toward decarbonization by reducing soot particle emissions

The article presents a method for obtaining catalytic systems: SiO2-Fe2O3, SiO2-Fe2O3-Fe and verification of their catalytic properties in the oxidation process of technical soot N550. The process of immobilization of Fe3+ ions on microsilica-SiO2 was investigated in the batch system (equilibrium, kinetics, thermodynamics). The process was aimed at obtaining a system with a developed surface and using less iron while maintaining the same catalysis active surface. In the next stages, the SiO2-Fe3+ systems were modified to obtain SiO2-Fe2O3 and SiO2-Fe2O3-Fe materials, which exhibited catalytic properties. To obtain catalytic systems, the processes of Fe3+ ions sorption, iron oxide precipitation - Fe2O3 and Fe reduction using a plant extract were used. Catalytic systems were applied in the N550 technical soot oxidation process to reduce the conversion temperature and increase its efficiency. The soot oxidation process was carried out in a muffle furnace using variable process parameters, i.e. temperature (450, 475, 500, 525 and 550oC), time (1, 2 and 3h), type of catalytic system (SiO2-Fe2O3, SiO2-Fe2O3-Fe) and its % content relative to the constant mass of soot (0, 10, 20 and 30%). The greatest increase in the conversion efficiency of soot particles was obtained using the SiO2-Fe2O3 system with a content of 20% at a temperature of 550oC and for 3 h.

Isotherms, kinetics and thermodynamics of industrial dye acid red 27 adsorption on Sugarcane Bagasse Ash

In this study, sugarcane bagasse ash (SCBA), obtained as residue from the sugar mill, was used as an adsorbent for Acid Red 27 (AR27) removal from aqueous solutions. The ash characterization data showed 23.63% of organic compounds and silica (α-SiO2) as the most expressive inorganic compound (confirmed by X-ray diffractogram), the BET surface area had a value of 62.79 m2.g-1 and the pHpzc was 8.45. Regarding the adsorptive tests, the optimal initial pH to the dye removal was 2.0. The adsorption equilibrium reached in about 4 h contact time and optimum SCBA dosage was found to be 4 g.L-1. The pseudo-second order model best represented the adsorption kinetics. The Freundlich equation presented the best fit to the equilibrium data for the removal of AR27 by ash, with maximum adsorption capacity of 15 mg.g-1 at pH 2.0. Thermodynamic study indicate that AR27 adsorption on SCBA occurs through a physisorption mechanism, with ΔHºads < 15 kJ.mol-1. The ΔHºads evaluated by Vant' Hoff equation was explained as a combination of water desorption enthalpy, ΔHºW and isosteric like enthalpy, ΔHºD for the dye adsorption in liquid environment. The ΔHºD = 9.2 kJ.mol-1 was calculated from Clausius-Clapeyron approach. The effects of coexisting anions on the adsorption and regeneration and reuse of the adsorbent were also investigated. This study suggests that SCBA, which was used without any pretreatment, has the potential to be applied as a low-cost adsorbent to mitigate effluents contamination with AR27 dye at low concentrations.

Synthesis of LDH-MgAl and LDH-MgFe composites for the efficient removal of the antibiotic from water

In this study, novel lamellar double hydroxide composites (LDH-MgAl and LDH-MgFe) were synthesized at different metal salt ratios (1:1 to 3:1) and fully characterized using various techniques such as XRD, FTIR, SEM, EDS, and TGA. The resulting LDHs demonstrated a high affinity for efficiently removing tetracycline (TC) antibiotic from water, particularly at a moderate molar ratio of 3:1. This ratio exhibited improved structural characteristics, resulting in better TC uptake from water. The improved performance was supported by the increased abundance of surface functional groups (OH, NO3, CO32-, C-O-C, Fe-O, and Al-O-Al). The TGA analysis established the high stability of the LDHs when subjected to high temperatures. The kinetics of TC adsorption onto LDH fitted with the PSO (R2 = 0.935-0.994) and Avrami (R2 = 0.9528-0.9824) models, while the equilibrium data fitted the Liu and Langmuir isotherm models, with maximum monolayer adsorption capacities of 101.1 mg g-1 and 70.83 mg g-1, respectively-significantly higher than many reported values in the literature. The positive values of ΔH0 and ΔS0 indicate an endothermic process, with TC removal mechanisms influenced by physical interactions, such as hydrogen bonding, electrostatic interaction, and π-cation with the surface functional groups of the LDH adsorbents. These results suggest that LDH-MgAl and LDH-MgFe are promising adsorbents for the removal of TC from water.

Regulating iron center by defective MoS2 for superior Fenton-like catalysis in water purification: The key role of surface interaction and superoxide radical in accelerating metal redox-cycling

Transition metals exhibit high reactivity for Fenton-like catalysis in environmental remediation, but how to save consumption and reduce pollution is of great interest. In this study, rationally designed defect-engineered Fe@MoS2 (Fe@D-MoS2) was prepared by incorporating reactive iron onto structural defects generated from the chemical acid-etching, aiming to improve the energetic consumption of the catalyst in Fenton-like applications. Morphological and structural properties were elucidated in details, the Fenton-like reactivity was evaluated with five phenolic contaminants for oxidant activation, radical generation and environmental remediation. Compared to Fe@MoS2, Fe@D-MoS2 exhibited a 18.9-fold increase in phenol degradation (0.09 versus 1.79 min-1). Quenching experiments, electron paramagnetic resonance tests and electrochemical measurements revealed the dominant sulfate and superoxide radicals. Rendered by strong metal-substrate surface and electronic interactions from regulated chemical environment and coordination structure, the inert ≡ Fe(III) was reduced to the reactive ≡ Fe(II) accompanied by the ≡ Mo(IV) oxidation to ≡ Mo(V) in MoS2 lattice, with adjacent sulfur serving as the key electron transfer bridge. Therefore, this work shows that the incorporation of reactive centers is able to boost two-dimensional sulfide materials for environmental catalysis applications.

One-step functionalization of chitosan with rich sulfur and nitrogen adsorption sites for efficient recovery of silver ions from actual wastewater

The recovery of silver ions from wastewater is of great importance due to their adverse environmental impact and significant economic value. This paper introduces a novel adsorbent (CS-AHMT) that can be easily synthesized via a one-step functionalization of chitosan with 4-Amino-3-hydrazino-1,2,4-triazol-5-thiol to efficiently recover silver ions from actual wastewater. CS-AHMT demonstrated superior adsorption performance, achieving an adsorption capacity of 241.4 mg·g-1 at pH 5 and 318 K, and the adsorption equilibrium was rapidly attained within 60 to 120 min. Kinetic and isotherm studies indicate that the adsorption process conforms to the pseudo-nth-order (PNO) and Sips models, suggesting a monolayer adsorption that incorporates both physical and chemical processes, with internal mass transfer being the primary rate-limiting step. Electrostatic and coordination interactions are primarily involved in the adsorption mechanism of silver ions on CS-AHMT, as further validated by density functional theory (DFT) calculations. The selectivity and practical applicability of CS-AHMT were confirmed in real wastewater containing high concentrations of competing ions. The findings underscore the potential of CS-AHMT as an effective adsorbent for silver ion recovery in wastewater treatment applications.

Sustainable application of modified Luffa cylindrica biomass for removal of trimethoprim in water by adsorption with process optimization

The present study describes a set of methodological procedures (seldom applied together), including (i) development of an alternative adsorbent derived from abundant low-cost plant biomass; (ii) use of simple low-cost biomass modification techniques based on physical processing and chemical activation; (iii) design of experiments (DoE) applied to optimize the removal of a pharmaceutical contaminant from water; (iv) at environmentally relevant concentrations, (v) that due to initial low concentrations required determination by ultra-performance liquid phase chromatography coupled to mass spectrometry (UPLC-MS/MS). A central composite rotational design (CCRD) was employed to investigate the performance of vegetable sponge biomass (Luffa cylindrica), physically processed (crushing and sieving) and chemically activated with phosphoric acid, in the adsorption of the antibiotic trimethoprim (TMP) from water. The optimized model identified pH as the most significant variable, with maximum drug removal (91.1 ± 5.7%) achieved at pH 7.5, a temperature of 22.5 °C, and an adsorbent/adsorbate ratio of 18.6 mg µg-1. The adsorption mechanisms and surface properties of the adsorbent were examined through characterization techniques such as scanning electron microscopy (SEM), point of zero charge (pHpzc) measurement, thermogravimetric analysis (TGA), specific surface area, and Fourier-transform infrared spectroscopy (FTIR). The best kinetic fit was obtained by the Avrami fractional-order model. The hypothesis of a hybrid behavior of the adsorbent was suggested by the equilibrium results presented by the Langmuir and Freundlich models and reinforced by the Redlich-Peterson model, which achieved the best fit (R2 = 0.982). The thermodynamic study indicated an exothermic, spontaneous, and favorable process. The maximum adsorption capacity of the material was 2.32 × 102 µg g-1 at an equilibrium time of 120 min. Finally, a sustainable and promising adsorbent for the polishing of aqueous matrices contaminated by contaminants of emerging concern (CECs) at environmentally relevant concentrations is available for future investigations.

Hybrid nanocellulose material as an adsorbent to remove reactive yellow 2 dye

Textile dyes are frequently disposable in aqueous effluents, making it difficult to remove them from industrial effluents before their release to natural waters. This paper deals with the fabrication of cellulose-based adsorbents by reacting nanocelulose crystalline (nanocel) with N-[3-(trimethoxysilyl)propyl]ethylenediamine (TMSPEDA), forming the hybrid (silylpropyl)ethylenediamine@nanocellulose (SPEDA@nanocel), which was employed as adsorbent for the uptake of reactive yellow 2 dye (RY-2) from aqueous effluents. Characterisation of SPEDA@nanocel was carried out using FTIR, SEM-EDS, XRD, TGA, surface area, pHpzc, and hydrophobicity/hydrophilicity ratio (HI). Also, adsorption studies were thoroughly investigated. The effect of initial pH indicated that the maximum uptake of RY-2 takes place at pH 2, which is an indication of the electrostatic mechanism. The kinetic data carried out with 250 and 500 mg L-1 RY-2 with SPEDA@nanocel followed better the nonlinear fractional-like pseudo-first-order model. The t0.5 and t0.95 for the dye uptake were about 30 and 141 min, respectively. The equilibrium data from 10 to 45 °C indicated that the Liu isotherm model was the best-fitted isothermal model. The maximum sorption capacity attained was 112.3 mg g-1 at 45 °C. The thermodynamic data have shown that the equilibrium was favorable and endothermic, and the ΔH° was compatible with an electrostatic attraction between RY-2 and SPEDA@nanocel. Experiments of desorption of loaded adsorbent showed promising results for real applications since at least 5 adsorption/desorption cycles could be employed without significant changes in the recovery and with high precision.

Novel activated carbon from Magonia pubescens bark: characterization and evaluation of adsorption efficiency

In this work, the synthesis of activated carbon from the bark of the Magonia pubescens (known as Tingui) and its efficiency in the removal of diclofenac sodium through batch adsorption tests and physical-chemical characterizations were investigated. The phytotoxicity of this material was also evaluated through germination and root growth of Lactuca sativa seeds. According to the experimental design performed for the synthesis of Tingui carbon, the optimized temperature and residence time for the production of this adsorbent were 550 °C and 120 min, respectively. The equilibrium time was reached in 600 min and the theoretical model that best fitted the kinetic data was the Elovich model. The BET was the best fit for the adsorption isotherm dataThis indicates that the adsorption process of sodium diclofenac by activated carbon can occur by two different mechanisms, monolayer and/or multilayer adsorption, depending on the conditions employed in the process, such as temperature and adsorbate concentration. The thermodynamic study showed that the process was favourable and spontaneous in the temperature range evaluated. Furthermore, the characterizations showed by TG/DTG and FTIR analyses that the temperature throughout the process had a marked impact on the degradation of the organic constituents of the biomass and the appearance of distinct functional groups that contributed to the adsorption process of diclofenac sodium. Finally, the toxicity tests recognized that this adsorbent does not affect the germination of L. sativa species. Thus, this adsorbent may become a novel and viable option to be used in the removal of sodium diclofenac.

Valorization of castor seed shell waste as lead adsorbent by treatment with hot phosphoric acid: Optimization and evaluation of adsorption properties

Lead is used in many industries such as refining, mining, battery manufacturing, smelting. Releases of lead from these industries is one of the major public health concerns due to widespread persistence in the environment and its resulting poisoning character. In this work, the castor seed shell (CSS) waste was exploited for preparing a beneficial bio-adsorbent for removal of Pb(II) ions from water. The raw CSS was modified with H3PO4 at different acid concentrations, impregnation ratios, activation times, and temperatures. An optimum adsorption capacity was observed for CSS modified with 2 M acid, 5 mL g-1 solid to liquid ratio, treated at 95 °C for 160 min. Exploiting acid modification, the SEM, XRD, and FTIR analyses show some alterations in functional groups and the surface morphology of the biomass. The impacts of physiochemical variables (initial lead ions concentration, pH, adsorbent dose and adsorption time) on the lead removal percentage were investigated, using response surface methodology (RSM). Maximum removal of 72.26% for raw CSS and 97.62% for modified CSS were obtained at an initial lead concentration (50 mg L-1), pH (5.7), adsorption time (123 min) and adsorbent dosage (1.1 g/100 mL). Isothermal and kinetics models were fitted to adsorption equilibrium data and kinetics data for the modified CSS and the adsorption system was evaluated thermodynamically and from the energy point of view. Isothermal scrutinization indicated the mono-layer nature of adsorption, and the kinetics experimental outcomes best fitted with the pseudo-second-order, implying that the interaction of lead ions and hot acid-treated CSS was the rate-controlling phenomenon of process. Overall, results illustrated that the hot acid-treated biomass-based adsorbent can be considered as an alternative bio-adsorbent for removing lead from water media.

Efficient adsorptive removal of 2,4-dichlorophenoxyacetic acid (2,4-D) using biomass derived magnetic activated carbon nanocomposite in synthetic and simulated agricultural runoff water

This study focused on evaluating the efficacy of a magnetic activated carbon material (CPAC@Fe3O4) derived from pods of copper pod tree in adsorbing the toxic herbicide, 2,4- (2,4-D) from aqueous solutions. The synthesized CPAC@Fe3O4 adsorbent, underwent various characterization techniques. FESEM images indicated a rough surface, incorporating iron oxide nanoparticles, while EDS analysis confirmed the presence of elements like Fe, O, and C. Notably, the CPAC@Fe3O4 exhibited high surface area (749.10 m2/g) and pore volume (0.5351 cm³/g), confirming its mesoporous nature. XRD investigations identified distinct signals associated with graphitic carbon and magnetite nanoparticles, while VSM analysis verified its magnetic properties with a high magnetic saturation value (2.72 emu/g). The adsorption process was exothermic, with a decrease in adsorption capacity at higher temperatures. Freundlich isotherm provided the best fit for the adsorption, and the pseudo-second-order equation effectively described the kinetics. Remarkably, the maximum adsorption capacity ranged from 246.43 to 261.03 mg/g, surpassing previously reported values. The ΔH° value (-8.67 kJ/mol) suggested a physisorption mechanism, and the negative ΔG° values established the spontaneous nature. Furthermore, the synthesized adsorbent demonstrated exceptional reusability, allowing for up to five cycles of adsorption-desorption operations. When applied to simulated agricultural runoff, CPAC@Fe3O4 showcased a significant adsorption capacity of 160.71 mg/g for 50 mg/L 2,4-D, using a 0.2 g/L dosage at pH 2. This study showcased the transformation of copper pod biomass into a valuable magnetic nanoadsorbent capable of efficiently eliminating the noxious 2,4-D pollutant from aqueous environments.