Green preparation of activated carbon from pomegranate peel coated with zero-valent iron nanoparticles (nZVI) and isotherm and kinetic studies of amoxicillin removal in water

Simultaneous removal of nitrogen, phosphorus, and organic matter from oligotrophic water in a system containing biochar and construction waste iron: Performances and biotic community analysis

The issue of combined pollution in oligotrophic water has garnered increasing attention in recent years. To enhance the pollutant removal efficiency in oligotrophic water, the system containing Zoogloea sp. FY6 was constructed using polyester fiber wrapped sugarcane biochar and construction waste iron (PWSI), and the denitrification test of simulated water and actual oligotrophic water was carried out for 35 days. The experimental findings from the systems indicated that the removal efficiencies of nitrate (NO3--N), total nitrogen (TN), chemical oxygen demand (COD), and total phosphorus (TP) in simulated water were 88.61%, 85.23%, 94.28%, and 98.90%, respectively. The removal efficiencies of actual oligotrophic water were 83.06%, 81.39%, 81.66%, and 97.82%, respectively. Furthermore, the high-throughput sequencing data demonstrated that strain FY6 was successfully loaded onto the biological carrier. According to functional gene predictions derived from the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, the introduction of PWSI enhanced intracellular iron cycling and nitrogen metabolism.

Conversion of char from pyrolysis of plastic wastes into alternative activated carbons for heavy metal removal

The valorization of post-consumer mixed plastics in pyrolysis processes represents an abundant reservoir of carbon that can be effectively converted into useful chars. This process not only holds appeal in terms of improving plastic waste concerns but also contributes to the reduction of greenhouse gas emissions, thus aligning with the principles of a circular economy paradigm. In this study, the char produced from the pyrolysis of post-consumer mixed plastic waste has been activated with Na2CO3, KOH, NaOH, and K2CO3 to improve the textural, structural, and composition characteristics, leading to improved adsorption capability. These characteristics were studied by N2 adsorption-desorption isotherms, scanning electron microscopy, elemental and immediate analysis, and X-ray photoelectron spectroscopy. The developed surface area (SBET) was 573, 939, 704 and 592 m2 g-1 for Na2CO3, KOH, NaOH and K2CO3 activated carbons, respectively. These activated chars (ACs) were tested for the adsorption of heavy metals in both synthetic waters containing Pb, Cd, and Cu and industrial wastewater collected at an agrochemical production plant. Na2CO3-AC was the best performing material. The metal uptake in synthetic waters using a batch set-up was 40, 13 and 12 mg g-1 for Pb, Cd and Cu. Experiments in a column set-up using Na2CO3-AC resulted in a saturation time of 290, 16, and 80 min for Pb, Cd, and Cu synthetic waters, respectively, and metal uptakes of 26.8, 4.1, and 7.9 mg g-1, respectively. The agrochemical effluents, containing mainly Cr, Cu, Mn, and Zn were tested in a plug-flow column. The metal uptake notably decreased compared to synthetic water due to a competition effect for active sites.

A new MOF-based modified adsorbent for the efficient removal of Hg(ii) ions from aqueous media: isotherms and kinetics

Herein, a new MOF-based modified adsorbent for the efficient removal of Hg(ii) ions from water media was successfully prepared. Initially, a MOF nanocomposite was synthesized and applied as an efficient adsorbent for the removal of the target heavy metal ion. Following the synthesis, the MOF-based modified adsorbent was identified and characterized by SEM, XRD and FT-IR analytical instruments. The impact of several key variables such as pH of aqueous solution, adsorbent dosage, contact time, and initial concentration of the analyte of interest on the adsorption efficiency was also investigated in detail. Under the optimal conditions established (pH, 3; dose of adsorbent, 0.4 g L-1; contact time, 40 min and the analyte's concentration of 1 mg L-1) the removal efficiency of 96.3% for Hg(ii) was obtained. The results of the studies on the isotherm and kinetics of adsorption revealed that the adsorption process of Hg(ii) matched with the Langmuir isotherm (R2 > 0.990) and the pseudo 2nd-order kinetic models (R2 > 0.998). Additionally, reuse of the applied adsorbent for five consecutive tests exhibited a small percentage of drop (about 8%) in the removal efficiency of the target ion. Finally, the results indicated that the MOF-based modified compound could be potentially applied as a highly efficacious adsorbent for the discharge of Hg(ii) from aquatic media.

From scraps to purification: innovative use of food waste-derived hydrochar in eradicating pharmaceutical pollutants

Chemical products (CPs) such as carbamazepine and naproxen, present in aquatic environments, pose significant risks to both aquatic life and human health. This study investigated the use of hydrothermally carbonized food waste-derived hydrochar (AC-HTC) at three distinct temperatures (200, 250, and 300 °C) as an adsorbent to remove these CPs from water. Our research focused on the impact of hydrothermal carbonization temperature on hydrochar properties and the effects of chemical activation with phosphoric acid on adsorption capacity. Hydrothermal carbonization increased the hydrochar's surface area from 1.47 to 7.52 m2/g, which was further enhanced to 32.81 m2/g after activation with phosphoric acid. Batch adsorption experiments revealed that hydrochar produced at 250 °C (AC-HTC-250) demonstrated high adsorption capacities of 49.10 mg/g for carbamazepine and 14.35 mg/g for naproxen, outperforming several conventional adsorbents. Optimal adsorption occurred at pH 4, aligning well with the Langmuir and pseudo-first-order models. The hydrochar showed potential for regeneration and multiple uses, suggesting its applicability in sustainable wastewater treatment. Future research will explore scalability and effectiveness against a broader range of pollutants.

Activated carbon and their nanocomposites derived from vegetable and fruit residues for water treatment

Water pollution remains a pressing environmental issue, with diverse pollutants such as heavy metals, pharmaceuticals, dyes, and aromatic hydrocarbon compounds posing a significant threat to clean water access. Historically, biomass-derived activated carbons (ACs) have served as effective adsorbents for water treatment, owing to their inherent porosity and expansive surface area. Nanocomposites have emerged as a means to enhance the absorption properties of ACs, surpassing conventional AC performance. Biomass-based activated carbon nanocomposites (ACNCs) hold promise due to their high surface area and cost-effectiveness. This review explores recent advancements in biomass-based ACNCs, emphasizing their remarkable adsorption efficiencies and paving the way for future research in developing efficient and affordable ACNCs. Leveraging real-time communication for ACNC applications presents a viable approach to addressing cost concerns.

Comprehensive life cycle assessment of NH2-functionalized magnetic graphene oxide for mercury removal: Carbon emissions and economic evaluation

Heavy metals contamination critically affects human health and ecosystems, necessitating pioneering approaches to diminish their adverse impacts. Hence, this study synthesized aminated magnetic graphene oxide (mGO-NH2) for the removal of mercury (Hg) from aqueous solutions. Although functionalized GO is an emerging technology at the early stages of development, its synthesis and application require special attention to the eco-environmental assessment. Therefore, the life cycle assessment and life cycle cost of mGO-NH2 were investigated from the cradle-to-gate approach for the removal of 1 kg Hg. The adsorption process was optimized based on pH, Hg concentration, adsorbent dose, and contact time at 6.48, 40 mg/l, 150 mg/l, and 35 min, respectively, resulting in an adsorption capacity of 184.17 mg/g. Human carcinogenic toxicity with a 40.42% contribution was the main environmental impact, relating to electricity (35.76%) and ethylenediamine (31.07%) usage. The endpoint method also revealed the pivotal effect of the mGO-NH2 synthesis on human health (90.52%). The most energy demand was supplied by natural gas and crude oil accounting for 70.8% and 22.1%, respectively. A 99.02% CO2 emission originated from fossil fuels consumption based on the greenhouse gas protocol (GGP). The cost of mGO-NH2 was about $143.7/kg with a net present value of $21064.8 per kg Hg removal for a 20-year lifetime. Considering the significant role of material cost (>70%), the utilization of industrial-grade raw materials is recommended to achieve a low-cost adsorbent. This study demonstrated that besides the appropriate performance of mGO-NH2 for Hg removal, it is essential that further studies evaluate eco-friendly approaches to decrease the adverse impacts of this emerging product.

Quartz crystal microbalance-based aptasensor integrated with magnetic pre-concentration system for detection of Listeria monocytogenes in food samples

A fast and accurate identification of Listeria monocytogenes. A new quartz crystal microbalance (QCM) aptasensor was designed for the specific and rapid detection of L. monocytogenes. Before detection of the target bacterium from samples in the QCM aptasensor, a magnetic pre-enrichment system was used to eliminate any contaminant in the samples. The prepared magnetic system was characterized using ATR-FTIR, SEM, VSM, BET, and analytical methods. The saturation magnetization values of the Fe3O4, Fe3O4@PDA, and Fe3O4@PDA@DAPEG particles were 57.2, 40.8, and 36.4 emu/g, respectively. The same aptamer was also immobilized on the QCM crystal integrated into QCM flow cell and utilized to quantitatively detect L. monocytogenes cells from the samples. It was found that a specific aptamer-magnetic pre-concentration system efficiently captured L. monocytogenes cells in a short time (approximately 10 min). The Fe3O4@PDA@DA-PEG-Apt particles provided selective isolation of L. monocytogenes from the bacteria-spiked media up to 91.8%. The immobilized aptamer content of the magnetic particles was 5834 µg/g using 500 ng Apt/mL. The QCM aptasensor showed a very high range of analytical performance to the target bacterium from 1.0 × 102 and 1.0 × 107 CFU/mL. The limit of detection (LOD) and limit of quantitation (LOQ) were 148 and 448 CFU/mL, respectively, from the feeding of the QCM aptasensor flow cell with the eluent of the magnetic pre-concentration system. The reproducibility of the aptasensor was more than 95%. The aptasensor was very specific to L. monocytogenes compared to the other Listeria species (i.e., L. ivanovii, L. innocua, and L. seeligeri) or other tested bacteria such as Staphylococcus aureus, Escherichia coli, and Bacillus subtilis. The QCM aptasensor was regenerated with NaOH solution, and the system was reused many times.

An effective magnetic nanobiocomposite: Preparation, characterization and its application for adsorption removal of P-nitroaniline from aquatic environments

In this investigation, a magnetic nanobiocomposite, denoted as CoFe2O4/Activated Carbon integrated with Chitosan (CoFe2O4/AC@Ch), was synthesized based on a microwave-assisted for the efficacious adsorption of P-nitroaniline (PNA). The physicochemical properties of the said nano biocomposite were thoroughly characterized using a suite of analytical methodologies, namely FESEM/EDS, BET, FTIR, XRD, and VSM. The results confirm the successful synthesis of the nanobiocomposite, with its point of zero charge (pHZPC) determined to be 6.4. Adsorptive performance towards PNA was systematically examined over a spectrum of conditions, encompassing variations in PNA concentration (spanning 10-40 mg/L), adsorbent concentration (10-200 mg/L), contact periods (2.5-22.5 min), and solution pH (3-11). Upon optimization, the conditions converged to an adsorbent concentration of 200 mg/L, pH 5, PNA concentration of 10 mg/L, and a contact duration of 22.5 min, under which an impressive PNA adsorption efficacy of 98.6% was attained. Kinetic and isotherm analyses insinuated the adsorption mechanism to adhere predominantly to the pseudo-second-order kinetic and Langmuir isotherm models. The magnetic nanocomposite was recovered and used in 4 cycles, and the absorption rate reached 86%, which shows the good stability of the magnetic nanocomposite in wastewater treatment. Conclusively, these empirical outcomes underscore the viability of the formulated magnetic nanobiocomposite as a potent, recyclable adsorbent for the proficient extraction of PNA from aqueous matrices.

Interstitial decoration of Ag linking 3D Cu2O octahedron and 2D CaWO4 for augmented visible light active photocatalytic degradation of rifampicin and genotoxicity studies

A morphological oriented highly active Cu2O-Ag-CaWO4 (CAC) nano-heterojunction was fabricated for the visible light driven degradation of rifampicin (RFP). Octahedron shaped Cu2O being a base material, where the Tagetes shaped CaWO4 and Ag were embedded on it. The shape-controlled morphology of Cu2O and CaWO4 as well as Ag decoration influence high degree of adsorption of RFP and interfacial charge transfer between the nano-heterojunction. Further, the larger specific surface area (129.531 m2/g) and narrow band gap energy (2.57 eV) of CAC nano-heterojunction than the controls support the statement. Positively, CAC nano-heterojunction following Z-scheme-type charge transport mechanism attained 96% of RFP degradation within 100 min. O2•- and •OH are the primarily involved reactive oxidation species (ROS) during the photocatalytic reactions, determined by scavenger study and ESR analysis. The stability and reusability of the CAC nano-heterojunction was assessed through performing cyclic experiment of RFP degradation and it holds 96.8% of degradation even after 6th cycle. The stability of CAC nano-heterojunction after photodegradation was further confirmed based on crystalline pattern (XRD analysis) and compositional states (XPS analysis). Intermediates formed during RFP degradation and its toxicity was discovered by using GC-MS/MS and ECOSAR analysis respectively. The end-product toxicity against bacterial system and genotoxicity of CAC nano-heterojunction against Allium cepa were evaluated and the results were seemed to have no negative causes for the aquatic lives.

Performance and mechanism of graphene oxide removal from aqueous solutions by calcite: adsorption isotherms, thermodynamics, and kinetics

The flow of graphene oxide (GO) into natural water systems can adversely affect water environments and ecosystems. In this study, the adsorption effect of calcite on GO under different conditions was studied using calcite as adsorbent. Meanwhile, characterized by a combination of microscopic experiments, including SEM, TEM, XRD, FTIR, Raman, XPS, and AFM, additional research on the performance and the mechanism of GO sorption by calcite was conducted. The findings indicated that the highest adsorption efficiency was observed at a temperature of 303 K, pH 3, a mass of 90 mg of calcite, with an initial concentration of 60 mg L-1 GO, resulting in a 95% adsorption rate. The adsorption isotherm conformed to the model of Langmuir and Temkin, and it is a heat absorption process dominated by monolayer adsorption. The thermodynamic analysis showed that the adsorption was spontaneous and heat-absorbing. The adsorption kinetics conformed to the pseudo-second-order kinetic model, and the sorption procedure is chemisorption. In conclusion, calcite has a good sorption capacity for GO, which can provide a reference for the removal of GO in the aqueous environment.

Environmental remediation of the norfloxacin in water by adsorption: Advances, current status and prospects

Antibiotics are considered as the new generation water pollutants as these disturb endocrine systems if water contaminated with antibiotics is consumed. Among many antibiotics norfloxacin is present in various natural water bodies globally. This antibiotic is considered an emerging pollutant due to its low degradation in aquatic animals. Besides, it has many side effects on human vital organs. Therefore, the present article discusses the recent advances in the removal of norfloxacin by adsorption. This article describes the presence of norfloxacin in natural water, consumption, toxicity, various adsorbents for norfloxacin removal, optimization factors for norfloxacin removal, kinetics, thermodynamics, modeling, adsorption mechanism and regeneration of the adsorbents. Adsorption takes place in a monolayer following the Langmuir model. The Pseudo-second order model represents the kinetic data. The adsorption capacity ranged from 0.924 to 1282 mg g-1. In this sense, the parameters such as the NFX concentration added to the adsorbent textural properties exerted a great influence. Besides, the fixed bed-based removal at a large scale is also included. In addition to this, the simulation studies were also discussed to describe the adsorption mechanism. Finally, the research challenges and future perspectives have also been highlighted. This article will be highly useful for academicians, researchers, industry persons, and government authorities for designing future advanced experiments.

Renewable-based treatment solution of Reactive Blue 21 dye on fly ash as low-cost and sustainable adsorbent

This study investigated the removal of Reactive Blue 21 (RB 21) dye from aqueous solutions by adsorption, evaluating the waste fly ash (FA). The effects of the parameters, such as initial dye concentration (100-750 mg/L), initial pH (2.0-8.0), adsorbent dose (1.0-4.0 g/L), and temperature (298-323 K) on the adsorption process were investigated. The optimum initial pH value was 2.0 for the highest RB21 dye removal (75.2 mg/g). At optimized conditions (pH 2.0, an adsorbent dosage of 1.0 g/L, a dye concentration of 750 mg/L, and an equilibrium time of 72 h), the highest adsorption capacity was found to be 105.2 mg/g. Moreover, the results of the kinetic studies fitted the pseudo-second-order kinetic model. Equilibrium data were best represented by the Langmuir isotherm model, with a maximum monolayer adsorption capacity of 103.41 mg/g at 323 K. ΔGads0 values were negative and varied from 11.64 to 9.50 kJ/mol in the temperature range of 298-323 K, the values of enthalpy (ΔHadso) and entropy (ΔSadso) of thermodynamics parameters were calculated as 37.62 kJ/mol and 86.67 J/mol K, respectively, indicating that this process was endothermic. Furthermore, the adsorbent costs for powdered activated carbon (PAC) and FA to remove 1 kg of RB 21 dye from aqueous solutions are calculated as 2.52 U.S. $ and 0.34 U.S. $, respectively. It is seen that the cost of FA is approximately 7.4 times lower than PAC. The results showed that FA, a low-cost industrial waste, was promising for the adsorption of RB 21 from aqueous solutions.

Advancement in nanomaterials for environmental pollutants remediation: a systematic review on bibliometrics analysis, material types, synthesis pathways, and related mechanisms

Environmental pollution is a major issue that requires effective solutions. Nanomaterials (NMs) have emerged as promising candidates for pollution remediation due to their unique properties. This review paper provides a systematic analysis of the potential of NMs for environmental pollution remediation compared to conventional techniques. It elaborates on several aspects, including conventional and advanced techniques for removing pollutants, classification of NMs (organic, inorganic, and composite base). The efficiency of NMs in remediation of pollutants depends on their dispersion and retention, with each type of NM having different advantages and disadvantages. Various synthesis pathways for NMs, including traditional synthesis (chemical and physical) and biological synthesis pathways, mechanisms of reaction for pollutants removal using NMs, such as adsorption, filtration, disinfection, photocatalysis, and oxidation, also are evaluated. Additionally, this review presents suggestions for future investigation strategies to improve the efficacy of NMs in environmental remediation. The research so far provides strong evidence that NMs could effectively remove contaminants and may be valuable assets for various industrial purposes. However, further research and development are necessary to fully realize this potential, such as exploring new synthesis pathways and improving the dispersion and retention of NMs in the environment. Furthermore, there is a need to compare the efficacy of different types of NMs for remediating specific pollutants. Overall, this review highlights the immense potential of NMs for mitigating environmental pollutants and calls for more research in this direction.

Bimetallic metal-organic framework as an efficient sorbent for the extraction of tacrolimus and cyclosporine from plasma before HPLC-MS/MS analysis

This study investigated the application of pores-size protocols into metal-organic frameworks that can lead to improved adsorption capacity of sorbents. A selective, fast, and sensitive analytical procedure based on dispersive solid phase extraction using a bimetallic metal organic framework named ZrZnMOF coupled with high-performance liquid chromatography-tandem mass spectrometry was established for the simultaneous quantification of tacrolimus and cyclosporine in plasma. The effects of several parameters, such as the dosage of sorbent, separation and elution times, volume and type of elution solvent, were investigated. Under optimal conditions, high extraction recovery (70 and 89 for tacrolimus and cyclosporine, respectively), low limits of detection (0.15 and 0.31 μg L-1 for tacrolimus and cyclosporine, respectively) and quantification (1.0 and 0.51 μg L-1 for tacrolimus and cyclosporine, respectively) wide linearity (1.0-1000 and 0.51-500 μg L-1 for tacrolimus and cyclosporine, respectively), and acceptable repeatability (n = 5, relative standard deviation less than 5.6 %) were attained. The validated method was successfully applied to quantify tacrolimus and cyclosporine A in plasma samples obtained from different volunteers.

Performance evaluation of PdO/ CuO TiO2 photocatalytic membrane on ceramic support for removing pharmaceutical compounds from water

This study investigated photocatalytic degradation of pharmaceutical compound using CuO or PdO-TiO2 membrane. The synthesized membranes were characterized by some techniques including X-ray powder diffraction (XRD), dynamic light scattering (DLS), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FT-IR). The structural properties confirmed that the photocatalytic membranes were successfully prepared on ceramic supports. The PdO-TiO2 and CuO-TiO2 membranes were employed as photocatalytic membranes to degrade metronidazole (MNZ) and diphenhydramine (DPH) in aqueous solutions, respectively. Some parameters affecting the photocatalytic reaction such as pH, initial concentration, and light source were also investigated. The maximum degradation for both pharmaceutical compounds was obtained at basic pH (pH = 10), low initial concentration (C0 = 10 ppm) under UV irradiation. At high transmembrane pressure (ΔP = 3 bar), the flow rate across the membrane increased up 0.0078 and 0.0082 cc/s.cm2 for CuO-TiO2 and PdO-TiO2 photocatalytic membrane respectively while not affected on degradation efficiency (DE). At the same condition operation (C0 = 10 ppm, pH = 10, ΔP = 2 bar under UV irradiation), the MNZ and DPH degradation of the PdO-TiO2 membrane was 94 and 95% respectively that relatively higher than the CuO-TiO2 membrane. It is probably due to the lower energy band gap of PdO-TiO2 (2.5 eV) than CuO-TiO2 (2.7 eV). The membrane stability tests confirmed the high performance of the prepared membranes.

Effect of mechanical-chemical modification on adsorption of beryllium by calcite

The treatment of beryllium wastewater has become a major problem in industry. In this paper, CaCO3 is creatively proposed to treat beryllium-containing wastewater. Calcite was modified by an omnidirectional planetary ball mill by a mechanical-chemical method. The results show that the maximum adsorption capacity of CaCO3 for beryllium is up to 45 mg/g. The optimum treatment conditions were pH = 7 and the amount of adsorbent was 1 g/L, and the best removal rate was 99%. The concentration of beryllium in the CaCO3-treated solution is less than 5 μg/L, which meets the international emission standard. The results show that the surface co-precipitation reaction between CaCO3 and Be (II) mainly occurs. Two different precipitates are generated on the used-CaCO3 surface; one is the tightly connected Be (OH)2 precipitation, and the other is the loose Be2(OH)2CO3 precipitation. When the pH of the solution exceeds 5.5, Be2+ in the solution is first precipitated by Be (OH)2. After CaCO3 is added, CO32- will further react with Be3(OH)33+ to form Be2(OH)2CO3 precipitation. CaCO3 can be considered as an adsorbent with great potential to remove beryllium from industrial wastewater.

Characterization of copper binding to different molecular weight fractions of dissolved organic matter in surface water

Dissolved organic matter (DOM) is a kind of substance with complex compositions and wide molecular weight distribution, which can strongly combine with various pollutants. Therefore, the binding characteristics of DOM and heavy metal pollutants can be studied specifically according to the binding characteristics of DOM and pollutants. In this study, DOM in surface water bodies was divided into three levels (MW < 1 kDa, 1 kDa < MW < 5 kDa, MW > 5 kDa) according to different molecular weights (MW). The binding properties were investigated by fluorescence spectrum analysis and complex model. Four components (C1-C4) were identified by PARAFAC. Among them, the contribution rate of protein-like components C1, C2 and C4 to the total fluorescence intensity reached more than 78%, and the log Ka values of low molecular weight components were the highest, which were 3.28, 3.14 and 3.47, respectively, indicating higher binding ability with Cu2+.With the decrease of molecular weight, the log Kb value increases, indicating that the complexation is more stable. The humic component C3 in high molecular weight has stronger binding stability with Cu2+, but the number of binding sites for C3 is 0.36, while that for C2 is 1.51, indicating that its binding sites and binding ability are relatively low. The results showed that the DOM ligand of Cu2+ in surface water showed a certain molecular weight dependence. In addition, different MW DOM lead to different pollution forms. Different properties of DOM ligand combined with Cu2+ were studied in order to control the migration, transformation, bioavailability, morphology and stability of heavy metal pollutants, and to provide theoretical support for the practical application management of surface water pollution control.

Extensive sorption of Amoxicillin by highly efficient carbon-based adsorbent from palm kernel: Artificial neural network modeling

In the present study, a new sorbent was fabricated from Palm kernel (PK) by dry thermochemical activation with NaOH and characterized by FTIR, X-ray diffraction, FE-SEM and BET, which was used for the Amoxicillin (AMX) sorption from aqueous solution. The influence of effective parameters such as pH, reaction time, adsorbent dosage, AMX concentration and ionic strength on the sorption efficacy of AMX removal were evaluated. The main functional groups on the surface of the magnetic activated carbon of Palm Kernel (MA-PK) were C-C, C-O, C[bond, double bond]O and hydroxyl groups. The specific surface of char, activated carbon Palm Kernel (AC-PK) and MA-PK were 4.3, 1648.8 and 1852.4 m2/g, respectively. The highest sorption of AMX (400 mg/L) was obtained by using 1 g/L of sorbent at solution pH of 5 after 60 min contact time, which corresponding to 98.77%. Non-linear and linear models of isotherms and kinetics models were studied. The data fitted well with Hill isotherm (R2 = 0.987) and calculated maximum sorption capacity were 719.07 and 512.27 mg/g from Hill and Langmuir, respectively. A study of kinetics shows that the adsorption of AMX follows the Elovich model with R2 = 0.9998. Based on the artificial neural network (ANN) modeling, the MA-PK dosage and contact time showed the most important parameters in the removal of AMX with relative importance of 36.5 and 25.7%, respectively. Lastly, the fabricated MA-PK was successfully used to remove the AMX from hospital wastewater.

Activated carbon-based pomegranate peels as an efficient removal method for carbamazepine

Pharmaceutical products found in wastewater and various water systems have become an environmental concern. Various processes were developed to remove various pharmaceuticals, including adsorption processes utilizing activated carbon adsorbents derived from agricultural wastes. The present study investigates the removal of carbamazepine (CBZ) from aqueous solutions by activated carbon (AC) derived from pomegranate peels (PGPs). The prepared AC was characterized by FTIR. The adsorption kinetics of CBZ on AC-PGPs was well represented by the pseudo-second-order kinetic model. Moreover, the data were well explained by Freundlich and Langmuir isotherm models. The effect of various parameters (including pH, temperature, CBZ concentration, the adsorbent dosage, and contact time) on the efficiency of CBZ removal by AC-PGPs was studied. The CBZ removal efficiency was not affected by changes in pH values but was slightly enhanced at the outset of the adsorption experiment with increasing temperature. The highest percentage removal efficiency was 98.0% at 23 °C when the optimum adsorbent dose was determined as 400.0 mg and the CBZ initial concentration was 20.0 mg L^-1. The general and potential applicability of this method is presented by using available agricultural wastes as a low-cost source of AC and as an efficient removal method of pharmaceuticals from aqueous solutions.

Measuring the effects of diethyl phthalate microplastics on marine algae growth using dielectric spectroscopy

This paper presents the development of a dielectric spectroscopy-based method using a customized, transmission line probe, fabricated on a printed circuit board (PCB), for monitoring the effect of diethyl phthalate (DEP) microplastics on marine algae growth. Experiments were performed by exposing marine algae (Chlorella pyrenoidosa) to DEP (0-50 mg) for up to 6 days. In order to amplify the electrophysiological effects and improve the sensing, a glutaraldehyde crosslinking agent was used and encapsulated on the surface of the probe. The reflection coefficient (S₁₁) and the complex permittivity (ɛ' & ɛ″) of the Medium Under Test (MUT) were investigated in the frequency range of 30 kHz-800 MHz. Without the presence of DEP, the number of algae (10⁴ cells/mL) and chlorophyll content (mg/L) increased at the rates of 207.73 × 10⁴ cells/mL and 148.1 mg/L per day, respectively. After 6 days of exposing Chlorella pyrenoidosa (C. pyrenoidosa) algae to different DEP concentrations, the growth rate decreased down to -11.92 × 10⁴ cells/mL and -19.19 mg/L (50 mg DEP), respectively. Additionally, the linearity of the relationship kept decreasing as the DEP content increased from R² = 0.9716 to R² = 0.1050 and from R² = 0.9293 to R² = 0.4961, respectively. Dielectric spectroscopy using the custom, transmission line probe, at 740 MHz, showed linear relationship (-1.22 dB/day) between the reflection coefficient (S₁₁) and hence complex permittivity (ɛ' & ɛ″) without the presence of DEP. However, as the DEP content increased, algae growth was prohibited more intensely, shown both from the number of algae and the chlorophyll content. This trend was reflected on S₁₁ and subsequently on the complex permittivity. This relationship confirms the capability of this method to monitor the growth of marine algae in almost real-time. This dielectric spectroscopy method could be a potential, low-cost tool to examine the impact of microplastic pollutants on marine microorganisms.

Removal of Malachite Green using carbonized material derived from disposable facemasks: optimization of removal process through Box-Behnken design

Water resources are being heavily contaminated due to the huge load of toxic pollutants released by industrial activities. Among various physical and chemical methods, adsorption is considered as a promising method for rapidly removing contaminants from wastewater. In the present study, a novel carbon-based adsorbent was prepared through controlled pyrolysis of disposable facemasks. The properties of carbonized compound (CC) were characterized by FTIR, XRD, SEM and EDX. The pollutant removal efficiency of CC was initially investigated with synthetic dyes Malachite Green (MG) and Congo Red (CR). The peaks observed in FTIR spectra corresponding to C=O and C=C and C-N functional groups on adsorbed CC surface confirm the interaction between dye and CC. The XRD spectra of CC showed strong peaks at 2θ = 26.629, 27.488, 27.810 and 29.404 which correspond to the disordered graphitic plane. The SEM images of CC showed good porosity nature. A quadratic model was developed through response surface methodology by conducting a series of Box-Behnken design experiments. Adequacy of this model variables was ensured by ANOVA tests at P-value <0.05. The lower P-value (<0.0001) and higher F-value (44.54) of the quadratic model showed it was a significant model for dye removal. Finally, the optimal condition to obtain maximum MG removal (rate >99%) was identified by desirability function as CC 1000 and MG 212 mg/L and adsorption time 180 min. Adsorption kinetic study indicates that a pseudo second-order kinetic model showed the best fit with R²=  0.999.

Facile adsorption-electroflotation method for the removal of heavy metal ions from water using carbon nanomaterials

Due to the none-biodegradable and carcinogenic nature of toxic metal ions, a novel sorption-electroflotation method was developed using carbon nanomaterials. The metal ions removed were Ni(II), Co(II), Zn(II), Fe(II), and Cu(II) using carbon nanotubes (CNTs) and carbon nanoshells (CNSs). The porous structure, morphology, composition, and surface properties of carbon nanomaterials, viz. the presence and number of functional groups are characterized by methods of low-temperature nitrogen adsorption, scanning electron microscopy, Boem, X-ray photoelectron spectroscopy. The surface of the materials was rough with varied particle sizes. Regardless of the sorbed ion and the nature of the nanomaterial, the Langmuir, Temkin, Dubinin-Radushkevich, and Flory-Higgins models were applied to the data. The maximum sorption removal on CNTs were 15.0-69.0, 36.0-75.0, 33.0-72.0, 18.0-70.0, 29.0-69.0% for Fe(II), Zn(II), Co(II), Cu(II), and Ni(II) while these values on CNSs were 19.0-53, 23.0-58.0, 30.0-79.0, 12.0-46.0, and 41.0-86%. But after simultaneous sorption-electroflotation, the percentage removal was 99.0, 97.0, 95.0, 99.0, and 52% for these metal ions, indicating an excellent combination of sorption-electro flotation. The method is highly beneficial to work in varied pH ranges as sorption and electroflotation gave the best results in acidic and basic mediums. The method is very effective, efficient, and inexpensive and can be used for the removal of the reported metal ions in water.

Escherichia coli inactivation in water by sulfate radical-based oxidation process using FeCl3-activated biochar/persulfate system

Pathogenic microbes in water present great risks to environments, water resources, and human health. In the present study, for the first time, a FeCl₃-activated bermudagrass-derived biochar (FA-BC) was applied to activate persulfate (PS) for E. coli inactivation. The PS activation was ascribed to the presence of Fe⁰ and Fe₃O₄ on the surface of FA-BC, and SO₄^·- radicals were proved to be the main role for E. coli inactivation using FA-BC activated PS system (FA-BC/PS). Decreasing the pH (5-9) and increasing the PS concentration (50-300 mg/L), reaction temperature (20-50 °C), and FA-BC dosage (100-500 mg/L) resulted in the enhancement of disinfection efficiency of E. coli using FA-BC/PS. 6.21 log reductions of E. coli were achieved within 20 min under the optimal conditions (500 mg/L FA-BC, 200 mg/L PS, pH 7, and 20 °C with 10⁷ CFU/mL E. coli in DI water). The FA-BC/PS effectively eliminated various initial concentrations of E. coli (10⁵-10⁸ CFU/mL). The E. coli inactivation rate decreased from 0.1426 min^-1 to 0.0883, 0.1268 min^-1, and 0.1093 min^-1 with the presence of 10 mg/L humic acid, 100 mg/L Cl^-, and 100 mg/L HCO₃^-, respectively. In addition, after three cycles of disinfection tests using FA-BC/PS, the E. coli inactivation rate only slightly decreased from 0.1426 to 0.1288 min^-1. The FA-BC/PS also effectively removed the E. coli in real stormwater with a 99.2 % inactivation efficiency within 180 min. The FA-BC/PS in fixed-bed column tests revealed the continuous and high inactivation of E. coli in water. Increasing the FA-BC amount (1.5 %-5 %) and PS concentration (50-200 mg/L) and decreasing the flow rate (2-4 mL/min) caused the lower E. coli concentration in effluent. Therefore, the FA-BC/PS can be considered as a promising and efficient technique for water disinfection.

Machine learning modelling of removal of reactive orange RO16 by chemical activated carbon in textile wastewater

This study develops machine learning model of removal of reactive orange dye (Azo) RO16 from textile wastewater by chemical activated carbon CAC. The study addresses the contamination removal efficiency with respect to changing dynamics of concentration, temperature, time, pH and dose, respectively. Machine learning based learning multiple polynomial regression is implemented to fit a model on the experimental observed data. The machine learns from the data and fit the multiple polynomial regression model for the data. The observed and predicted data are in close agreement with the R-squared value of 92%. The results show that the baseline efficiency of using chemical activated carbon adsorbent for removing RO16 is 76.5%. The most significant input parameter increasing the efficiency by a constant value of 35 units out of 100 is the second order response of the dose. Moreover, four input parameters can considerably increase the efficiency. Furthermore, six input parameters can considerably decrease the efficiency. It is investigated, that the second order response with respect to time has the minute decreasing effect on the removal efficiency. The superior abilities of the modeling are two fold. Firstly, the contamination removal of reactive orange dye (Azo) RO16 with chemical activated carbon adsorbent is studied with respect to five multiple parameters. Secondly, the model exploits the machine learning capability of the renowned Python machine learning module sklearn to fit a multiple polynomial regression model. Thus a robust model is fitted giving twenty-one inputs/output interactions and responses. From the input-target correlation analysis it is clear that the removal efficiency has a strong correlation with the time. It has considerably significant relationship with dose of the CAC and the temperature with values of 18% and 17%, respectively. Moreover, the removal efficiency has inverse relations with pH and Ci, with values of 15% and 12%, respectively.

Total petroleum hydrocarbons and influencing factors in co-composting of rural sewage sludge and organic solid wastes

Co-composting is an efficient strategy for collaborative disposal of multiple organic wastes in rural areas. In this study, we explored the co-composting of rural sewage sludge and other organic solid wastes (corn stalks and kitchen waste), with a focus on the variation of total petroleum hydrocarbons (TPH) during this process. 12% corn-derived biochar was applied in the composting (BC), with no additives applied as the control treatment (CK). The TPH contents of piles after composting ranged from 0.70 to 0.74 mg/g, with overall removal efficiencies of 35.6% and 61.1% for CK and BC, respectively. The results indicate that the addition of 12% biochar increased the rate of TPH degradation and accelerated the degradation process. 16s rDNA high-throughput sequencing was applied to investigate the biodiversity and bacterial community succession during the composting process. Diverse bacterial communities with TPH degradation functions were observed in the composting process, including Acinetobacter, Flavobacterium, Paenibacillus, Pseudomonas, and Bacillus spp. These functional bacteria synergistically degraded TPH, with cooperative behavior dominating during composting. Biochar amendment enhanced the microbial activity and effectively promoted the biodegradation of TPH. The physicochemical properties of the compost piles, including environmental factors (pH and temperature), nutrients (nitrogen, phosphorus, potassium), and humic substances produced in composting (humic acids and fulvic acids), directly and indirectly affected the variation in TPH contents. In conclusion, this work illustrates the variation in TPH content and associated influencing factors during co-composting of rural organic solid wastes, providing valuable guidance toward the further optimization of rural organic waste management.

Nitrogen-doped magnetic porous carbon material from low-cost anion-exchange resin as an efficient adsorbent for tetracyclines in water

In this work, nitrogen-doped magnetic porous carbon material (N-MPC) was prepared through the high-temperature calcination of low-cost [Fe(CN)₆]^3--loaded anion-exchange resin, which was experimentally demonstrated to have significant adsorption performance for tetracycline (TC) in water. The N-MPC adsorbent with a large specific surface area (781.1 m² g^-1) was able to maintain excellent performance in a wide pH range from 4 to 10 or in high ionic strength solution. The adsorption of TC on N-MPC was found to be more consistent with the pseudo-second-order model and Langmuir adsorption model, and the maximum adsorption capacity (q_{m, cal}) was calculated to be 603.4 mg g^-1. As a recoverable magnetic adsorbent, the N-MPC remained a TC removal rate higher than 70% after four adsorption cycles. The adsorption mechanism was speculated on the basis of characterizations, where pore filling, hydrogen bonding interaction, and π-π electron donor-acceptor (EDA) interaction were crucial adsorption mechanisms. A variety of antibiotics were selected for adsorption, and excellent performance was found especially for TCs, indicating that the N-MPC can be used for the efficient removal of TCs from water.

Preparation and characterization of activated carbon from agricultural wastes and their ability to remove chlorpyrifos from water

Chlorpyrifos is an organophosphate insecticide linked to neurological dysfunctions, endocrine disturbance, cardiovascular illness, genotoxicity, histopathological abnormalities, immunotoxicity, and oxidative stress. Therefore, the aim of this study was to prepare activated carbon from agricultural waste to adsorb and remove chlorpyrifos from aqueous solutions, as well as to study the physicochemical characteristics of the prepared activated carbon.Activated carbon was prepared from agricultural waste (banana peels, orange peels, pomegranate peels and date stones). The activated carbon prepared showed an exterior surface that was irregular and full of cavities with Brunauer-Emmett-Teller(BET) surface areas of 94.26, 111.75, 183.89, and 289.86 m²/g for activated carbon prepared from orange peels, date stone, pomegranate peels, and banana peels respectively. The Scanning Electron Microscope (SEM) image revealed that the activated carbon's exterior surface was irregular and full of various shapes and sizes of cavities.The Energy Dispersive X-Ray (EDX) indicated the existence of carbon, oxygen, silicon and potassium in banana peels-derived activated carbon, whereas carbon, oxygen, silicon and potassium, in addition to aluminium, were detected in the pomegranate peels-derived activated carbon. The Fourier-Transform Infrared Spectroscopy (FTIR) analysis of prepared activated carbon revealed several functional groups, including carboxylic acid, carbon dioxide, and aromatic compounds. Results also showed that the activated carbon significantly removed chlorpyrifos from water, recording 97.6%, 90.6%, 71.48%, and 52.00 % for activated carbon prepared from pomegranate peels, banana peels, date stones and orange peels, respectively. The study concluded that agricultural waste-derived activated carbon could be employed as an alternative pesticide adsorbent.

Mesoporous carbon material prepared from sewage sludge hydrochar using Pluronic F127 as template for efficient removal of phenolic compounds: Experimental study and mechanism interpretation via advanced statistical physics model

Mesoporous carbon material (MCM) with rich ether surface group was prepared from sewage sludge hydrochar using Pluronic F127 as template under pyrolysis activation, which provided an energy-efficient method to promote the resource utilization of sewage sludge as adsorbents for phenols removal from water. The MCM possessed high surface area (549 m²/g), abundant mesopores (average width 3.81 nm) and well-developed graphite structure. Acidic conditions and low temperatures favored the adsorption of phenolic compounds. The quick adsorption process of reaching over 85% of the capacity in the first 10 min and intraparticle diffusion as primary rate-limiting step were observed for all phenolic compounds. Advanced statistical physics analysis was used successfully to interpret the adsorption mechanism of phenols onto MCM and revealed a multi-molecular monolayer adsorption process primarily through negative charge-assisted hydrogen bond interaction where the ether functional group contributed to the predominant active sites. The adsorption capacity of phenolic compounds depended upon the number of molecules adsorbed per ether active site and the available density of ether bond group on the surface of MCM. 2,4,6-trichlorophenol showed a highest adsorption priority to occupy the limited ether active sites and its adsorption capacity reached 0.49 mmol/g, while p-nitrophenol exhibited a maximum number of molecules adsorbed on the single ether active site, showing an adsorption capacity of 0.42 mmol/g. The synergistic effect of multi-interactions mechanisms resulted in phenolic compounds removal with adsorption energies lower than 30 kJ/mol. This prepared MCM adsorbent is promising for application in treatment of water polluted by phenols.

Deciphering the effects of antibiotics on nitrogen removal and bacterial communities of autotrophic denitrification systems in a three-dimensional biofilm electrode reactor

In this study, three-dimensional biofilm electrode reactors (3D-BERs) were constructed, and the effects of metronidazole (MNZ) on the nitrogen removal performance and bacterial communities of autotrophic denitrification systems were evaluated. The results showed that nitrogen removal decreased slightly as the MNZ concentration increased. Specifically, nitrate-nitrogen removal efficiency decreased from 97.98% to 89.39%, 86.93%, 82.64%, and 82.77% within 12 h after the addition of 1, 3, 5, and 10 mg/L MNZ, respectively. The 3D-BERs showed excellent MNZ degradation ability, especially at a concentration of 10 mg/L. The MNZ removal efficiency could be as high as 94.38% within 6 h, and the average removal rate increased as the MNZ concentration increased. High-throughput sequencing results showed significant changes in the bacterial community under different MNZ concentrations. As the antibiotic concentration increased, the relative abundances of Hydrogenophaga and Silanimonas increased, from only 0.09% and 0.01% without antibiotics to 3.55% and 2.35%, respectively, at an antibiotic concentration of 10 mg/L. Changes in antibiotic concentration altered the abundances of genes involved in nitrogen metabolism. Redundancy analysis showed that MNZ removal efficiency was positively correlated with SBR1031, SC-I-84, Hydrogenophaga, Silanimonas and Denitratesoma, whereas the removal efficiencies of nitrate-nitrogen and total nitrogen were negatively correlated with these genera. The results of this study provide a theoretical basis for studying the toxic effects of antibiotics on the denitrification process and also provide guidance for the control of antibiotics and nitrogen pollution in ecosystems.

Novel control strategies for the endocrine-disrupting effect of PAEs to pregnant women in traffic system

Traffic-related air pollution has become a global issue, and scientific regulation measures are urgently needed to reduce traffic pollution. Phthalates (PAEs) have been widely detected in the traffic environment; thus, they were chosen as target pollutants because of their endocrine-disrupting effects. The pathways of action and mechanisms of PAEs' endocrine-disrupting effects in pregnant women through inhalation were deduced. A novel whole-process 1C + 3D + 5R regulation system was developed to control the endocrine-disrupting effect of PAEs on pregnant women based on the cleaning production concept. (1) For source reduction, the 2D-QSAR model of endocrine-disrupting effects of PAEs in pregnant women was constructed to screen out the key influencing factors as hydrogen bond interaction and hydrophobic interaction. Based on this, a designed PAE substitute molecule with low volatility and endocrine-disrupting effects and no developmental toxicity was screened. The substitute molecule could reduce the volatilization amount of PAEs at the source by 41.76 %; (2) For process interception, selecting C-band UV light to eliminate PAEs molecules in the traffic environment can slow down 19.99 % of the endocrine-disrupting effect of PAEs molecules. The homology modeling method was used to design four kinds of green belt plant proteins with high PAEs absorption efficiency to absorb PAEs molecules in the traffic environment. Compared with the original green belt plant proteins, the absorption amount of PAEs increased by up to 96.08 %, and (3) For terminal prevention, dietary food schemes were designed to regulate PAEs' endocrine-disrupting effect on pregnant women. The optimal dietary food scheme was the simultaneous intake of glutamate, catechin and folic acid, which could reduce the adverse effect of PAEs on maternal and infants by 32.51 %. This study presents theoretical support for regulating PAE exposure to specific populations in the traffic environment and treating other pollutants in the future.

Selective Removal of Boron from Aqueous Solutions Using ECH@NGM Aerogels with Excellent Hydrophilic and Mechanical Properties: Performance and Response Surface Methodology Analysis

The remediation of environmental boron contamination has received extensive research attention. The adsorbent ECH@NGM aerogel with high hydrophilic and mechanical properties was synthesized to remove boron. The ECH@NGM aerogel had a high adsorption capacity of 81.11 mg/g, which was 14.50% higher than that of commercial boron-selective resin Amberlite IRA743. The Freundlich model and pseudo-second-order model described the adsorption behavior well. In addition, the response surface methodology (RSM) could predict the experimental outcomes and optimize the reaction conditions, and X-ray photoelectron spectroscopy (XPS) and control tests were utilized to investigate probable adsorption mechanisms. These data showed that the B ← N coordination bond was the primary adsorption force. The adsorbent had good resistance to interference from coexisting salts, high reusability, good adsorption performance even after five reuse cycles, and a high desorption rate in a relatively short time. The adsorption performance in real brines could be maintained at 80%. Therefore, this work not only provided ECH@NGM aerogels for the removal of boron from brine but also elucidated the main adsorption processes between N-containing adsorbents and boron, facilitating the design of future adsorbents for boron removal.

Sorption and continuous filtration of heavy metals and radionuclides using novel nano-Farringtonite: Mechanisms delineation using EXAFS

Simultaneous removal of a wide range of toxic heavy metal cations and potential radionuclides from water bodies and their continuous filtration with a single low-cost and eco-friendly material represents several scientific merits. Herein, for the first time, we report the simple and straightforward wet-chemical synthesis of novel nano-Farringtonite (FAR) composed of magnesium and phosphate ions. Further, the potential of known alternate nano-hydroxyapatite (HAP) and novel engineered nano-FAR including their non-stoichiometric variations was evaluated for the removal of mimicking radionuclide (Sr²⁺) and heavy metals (Cd²⁺, and Zn²⁺) from water bodies. Non-stoichiometric FAR (ns-FAR) have shown multifold higher contaminant removal capacities than HAP, i.e., Sr²⁺≈ 85 mg/g vs 49.5 mg/g, Cd²⁺≈ 560 mg/g vs 98.5 mg/g, and Zn²⁺ = 489 mg/g vs 62 mg/g in batch mode. NsFAR showed complete removal of Cd²⁺ and Zn²⁺ with <20% and 0% recovery, respectively in three consecutive sorption-recovery cycles, probing towards permanent incorporation of these ions. Spectroscopic analysis and extended x-ray absorption fine structure (EXAFS) spectroscopy fitting confirmed ion exchange and crystal incorporation as probable removal mechanisms. The high ionic potential of Mg²⁺ allows easy ion exchange with +2 charged metal toxins of varying ionic radius at both Mg1 and Mg2 sites of FAR. nsFAR showed instantaneous separation of these cations in continuous column mode with >2,00,000 L/kg of water filtration capacity (at 1 mg/L), justifying the adsorbent's candidature in water purification applications.

New bismuth oxyiodide/chitosan nanocomposite for ultrasonic waves expedited adsorptive removal of amoxicillin from aqueous medium: kinetic, isotherm and thermodynamic investigations

Amoxicillin (AMX) is a widely used antibiotic, which induces harmful effects to nature via bioaccumulation and persistence in the environment if discharged untreated into water bodies. In the current study, a novel bionanocomposite, bismuth oxyiodide-chitosan (BiOI-Ch), was synthesized by a facile precipitation method and its amoxicillin (AMX) adsorption capacity in the presence of ultrasonic waves has been explored. Multiple batch experiments were performed to achieve the optimum operational parameters for maximum adsorption of AMX and the obtained results were as follows: pH 3, 80 mg g^-1 AMX concentration, 1.7 g L^-1 adsorbent dose, temperature 298 K and ultrasonication time 20 min. Composite removed approximately 90% AMX from the solution under optimized conditions, while the maximal adsorption capacity was determined to be 81.01 mg g^-1. BiOI-Ch exhibited superior adsorption capacity as compared to pure BiOI (33.78 mg g^-1). To understand the dynamics of reaction, several kinetic and isotherm models were also examined. The adsorption process obeyed pseudo-second-order kinetic model (R² = 0.98) and was well fitted to Freundlich isotherm (R² = 0.99). The addition of biowaste chitosan to non-toxic bismuth-based nanoparticles coupled with ultrasonication led to enhanced functional groups as well as surface area of the nanocomposite resulting in superior adsorption capacity, fast adsorption kinetics and improved mass transfer for the removal of AMX molecules. Thus, this study demonstrates the synergistic effect of ultrasonication in improved performance of novel BiOI-Ch for potential application in the elimination of persistent and detrimental pollutants from industrial effluent after necessary optimization for large-scale operation.

The Influence of NH4NO3 and NH4ClO4 on Porous Structure Development of Activated Carbons Produced from Furfuryl Alcohol

The influence of NH₄NO₃ and NH₄ClO₄ on the porous texture and structure development of activated carbons produced from a non-porous polymeric precursor synthesized from furfuryl alcohol has been studied. The non-doped counterparts were prepared and studied for comparison purposes. NH₄NO₃ and NH₄ClO₄-doped polymers were carbonized under N₂ atmosphere at 600 °C, followed by CO₂ activation at 1000 °C and the obtained carbon materials and activated carbons were thoroughly characterized. The porosity characterization data have shown that NH₄NO₃-derived ACs present the highest specific surface area (up to 1523 m²/g in the experimental conditions studied), and the resulting porosity distributions are strongly dependent on the activation conditions. Thus, 1 h activation is optimum for the microporosity development, whereas larger activation times lead to micropores enlargement and conversion into mesopores. The type of doping salts used also has a substantial impact on the surface chemical composition, i.e., C=O groups. Moreover, NH₄NO₃ and NH₄ClO₄ constitute good sources of nitrogen. The type and contribution of nitrogen species are dependent on the preparation conditions. Quaternary nitrogen only appears in doped samples prepared by carbonization and pyrrolic, pyrydinic, and nitrogen oxide groups appear in the NH₄NO₃ -series. NH₄NO₃ incorporation has led to optimized materials towards CO₂ and C₂H₄ sorption with just 1 h activation time.

Removal of Cr(III) from Aqueous Solution Using Labeo rohita Chitosan-Based Composite

This study focusses on the synthesis of chitosan-cellulose composite membrane derived from Labeo rohita fish scales (FS) for the removal of Cr(III) from aqueous solution, while chromium is a serious threat to groundwater. Waste FS are valorized to chitosan by demineralization, deproteination, and deacetylation successively. Cellulose was extracted from sugarcane bagasse using acidic hydrolysis. Chitosan-based cellulose composite porous membrane was fabricated by evaporating solvent from polymer solution in petri dish. The impact of pH, contact time, and absorbent dosage on the removal of Cr(III) from an aqueous solution was investigated. Atomic absorption spectrophotometer was used to check the Cr(III). Results showed that chitosan comprising 85% degree of deacetylation was achieved by alkali treatment, while yield was 22%. FTIR analysis confirmed the chitosan and chitosan-cellulose-based composite membrane. Morphology studies showed that the cellulose was strongly staggered and due to the chitosan, the surface of cellulose became rougher, which is good to enhance the adsorption capacity. The maximum removal 57% of Cr(III) from aqueous solution was observed at pH 6 at 60 min and 50 mg dosage of adsorbent. The minimum removal (47%) of Cr (III) was found at pH 2. These results confer that Labeo rohita-based chitosan-cellulose composite membrane has great potential for the removal of metals from industrial effluents.