Evaluation of natural and cationic surfactant modified pumice for congo red removal in batch mode: Kinetic, equilibrium, and thermodynamic studies

Adsorption properties of cellulose-derived hydrogel and magnetic hydrogels from Sophora flavescens on Cu2+ and Congo red

This study synthesized a robust, magnetically responsive hydrogel from Sophora flavescens-modified cellulose and chitosan, employing Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA and DTG), and scanning electron microscopy (SEM) to confirm the preservation of cellulose's intrinsic properties and the hydrogel's remarkable elasticity, toughness, and porosity. These hydrogels integrate cellulose's structural backbone with functional moieties from chitosan, enhancing adsorption capabilities for Cu2+ ions and Congo red (CR) dye. Kinetic and thermodynamic analyses reveal that adsorption is spontaneous and endothermic, following a pseudo-second-order model and the Freundlich isotherm. Notably, Cu2+ adsorption capacity increases with pH, while CR adsorption initially decreases before rising, demonstrating the hydrogels' potential as effective, sustainable adsorbents for removing pollutants from water.

Kinetic and adsorption isotherm studies of Malachite Green dye onto surfactant-tailored alginate hydrogel beads: An influence of surfactant hydrophobicity

This study details the synthesis and characterization of surfactant-modified sodium alginate hydrogel beads crosslinked with Ba2+ ions through ionotropic gelation. Cationic surfactants such as, dodecyltrimethylammonium bromide (DTAB), didodecyldimethylammonium bromide (DDAB), and butanediyl-α,ω-bis-(dimethyldodecylammonium bromide) (GEM), were employed in the modification process. The surfactant-modified ALG-DTAB, ALG-DDAB, and ALG-GEM beads were investigated for the removal of cationic dye Malachite Green (MG) to elucidate the impact of hydrophobicity of amphiphiles on the adsorption process. The characterizations were carried out using Rheometry, Field Emission Scanning Electron Microscopy (FESEM), Infrared Spectroscopy (IR), and Energy Dispersive X-ray Spectroscopy (EDX). Under optimized conditions, ALG-GEM and ALG-DDAB demonstrated highest maximum adsorption capacity (Qmax > 700 mgg-1). The adsorption data fitted well to pseudo-second order kinetic and Langmuir adsorption models, suggesting the involvement of chemisorption phenomena with notable contributions from pore diffusion. The effects of pH, initial dye concentration, adsorbent dose, temperature, and competing ions on the removal of MG were investigated. Interestingly, ALG-GEM beads exhibited an increase in adsorption capacity with rising pH and a subsequent decrease with increasing temperature, showcasing optimal adsorption at pH 7.0 and 25 °C. The study proposes that ALG beads modified with cationic surfactants with higher hydrophobicity could offer a promising avenue in wastewater treatment processes.

Rapid removal of Rhodamine B by phosphoric acid-modified activated carbon derived from rape straw

A series of activated carbon was obtained from rape straw by chemical modification with phosphoric acid (H3PO4). The activated carbon was characterized and the adsorption capacity for Rhodamine B (RhB) from water was analysed. The SEM images showed that PRC-40 is a porous material and the BET analysis revealed a high surface area of 1720 m2/g with the coexistence of micropores and mesopores. The FTIR spectra determined the presence of oxygenated functional groups at its surface. The XPS spectra revealed that the content of carboxyl and metaphosphate groups in the modified activated carbon significantly increased, and this is conducive to the adsorption reaction. The XRD pattern showed the amorphous nature of carbon. The effect of significant parameters, such as the concentration of H3PO4 for modification and pH value, has been discussed. The kinetic data showed that the pseudo-second-order model is predominant. Besides, the Langmuir model was compatible well with the equilibrium data, and the maximum adsorption capacity of the activated carbon modified by H3PO4 was 2882.84 mg/g. Therefore, agricultural waste and rape straw can be used to prepare effective adsorbents for the application with the removal of dye from wastewater.

Preparation of cationic surfactant modified two-dimensional (2D) multi-layered Ti3C2Tx MXene for methyl orange removal from aqueous solution: Kinetic, equilibrium, and adsorption mechanisms

In this study, cetyltrimethylammonium bromide-modified multi-layered Ti3C2Tx MXene (CMM) was produced using a Ti3AlC2 precursor, and its capacity to remove the anionic dye, methyl orange (MO), was investigated in detail. An electrostatic combination between negatively charged Ti3C2Tx nanosheets and cationic surfactant solution (CTAB) produced this adsorbent. This triggered an exposure of the accessible active sites to further boost adsorption effectiveness by increasing the distance between the MXene nanosheets. Prepared adsorbents were characterized using some analytical techniques, including TGA, FESEM, EDX, FTIR, XRD, and N2 adsorption-desorption. Furthermore, some influencing parameters such as contact time, solution of pH, loading adsorbent, and initial dye concentration were evaluated, with findings showing that MO could adsorb CMM to its maximum capacity at an adsorbent dosage of 0.83 g/L, a contact time of 90 min, and a solution pH of 3. Adsorption results were found to be highly linked with both Langmuir isotherm (R2 = 0.9990) and the pseudo-second-order kinetic model (R2 = 0.9924). The maximum adsorption capacity of MO was obtained at approximately 213.00 mg/g. Also, hydrogen bonding, π-cation interactions, and electrostatic adsorption can all be implicated in the mechanism of MO adsorption on CMM. The fabricated CMM is presented as a prospective adsorbent for the removal of dyes from polluted water, demonstrating robust recyclability for up to the fifth iteration. All these outstanding properties indicate that cetyltrimethylammonium bromide-modified multi-layered Ti3C2Tx MXene can be considered as applicable adsorbents for textile pollutants.

Process Optimization and Equilibrium, Thermodynamic, and Kinetic Modeling of Toxic Congo Red Dye Adsorption from Aqueous Solutions Using a Copper Ferrite Nanocomposite Adsorbent

In the present investigation of copper ferrite, a CuFe2O4 nanocomposite adsorbent was synthesized using the sol-gel method, and its relevance in the adsorptive elimination of the toxic Congo red (CR) aqueous phase was examined. A variety of structural methods were used to analyze the CuFe2O4 nanocomposite; the as-synthesized nanocomposite had agglomerated clusters with a porous, irregular, rough surface that could be seen using FE-SEM, and it also contained carbon (23.47%), oxygen (44.31%), copper (10.21%), and iron (22.01%) in its elemental composition by weight. Experiments were designed to achieve the most optimized system through the utilization of a central composite design (CCD). The highest uptake of CR dye at equilibrium occurred when the initial pH value was 5.5, the adsorbate concentration was 125 mg/L, and the adsorbent dosage was 3.5 g/L. Kinetic studies were conducted, and they showed that the adsorption process followed a pseudo-second-order (PSO) model (regression coefficient, R2 = 0.9998), suggesting a chemisorption mechanism, and the overall reaction rate was governed by both the film and pore diffusion of adsorbate molecules. The process through which dye molecules were taken up onto the particle surface revealed interactions involving electrostatic forces, hydrogen bonding, and pore filling. According to isotherm studies, the equilibrium data exhibited strong agreement with the Langmuir model (R2 = 0.9989), demonstrating a maximum monolayer adsorption capacity (qmax) of 64.72 mg/g at pH 6 and 302 K. Considering the obtained negative ΔG and positive ΔHads and ΔSads values across all tested temperatures in the thermodynamic investigations, it was confirmed that the adsorption process was characterized as endothermic, spontaneous, and feasible, with an increased level of randomness. The CuFe2O4 adsorbent developed in this study is anticipated to find extensive application in effluent treatment, owing to its excellent reusability and remarkable capability to effectively remove CR in comparison to other adsorbents.

Preparation of a magnetic molecularly imprinted polymer on fibrous silica nanosphere via self-polycondensation for micro solid-phase extraction of chlorpyrifos

Throughout this research, a new magnetic molecularly imprinted polymer on fibrous silica nanosphere was prepared through self-polycondensation. The selective extraction of chlorpyrifos was performed by the synthesized sorbent and as a determination system, a gas chromatography-electron capture was applied. The formation of sorbent was confirmed through the use of Fourier transform infrared spectroscopy and field emission scanning electron microscopy techniques. The parameters affecting the extraction efficacy of the proposed method were scrutinized in an optimized way. The linear range and the detection limit of the studied method were 0.003-0.3 and 0.001 ng mL-1, respectively. The relative standard deviations were 4.1-5.2 and 5.6-7.6 % for intra- and inter-day (n = 3), respectively. To assess the performance of the proposed method, some water and fruit samples were analyzed and the extraction recoveries of 83-109 % were obtained. These results revealed the method's performance in the analysis of chlorpyrifos in real samples.

Fe3O4-lignin@Pd-NPs: A highly active, stable and broad-spectrum nanocomposite for water treatment

In this work, we report an environmentally friendly renewable nanocomposite magnetic lignin-based palladium nanoparticles (Fe3O4-lignin@Pd-NPs) for efficient wastewater treatment by decorating palladium nanoparticles without using any toxic reducing agents on the magnetic lignin abstracted from Poplar. The structure of composite Fe3O4-lignin@Pd-NPs was unambiguously confirmed by XRD, SEM, TEM, EDS, FTIR, and Zeta potential. After systematic evaluation of the use and efficiency of the composite to remove toxic organic dyes in wastewater, some promising results were observed as follows: Fe3O4-lignin@Pd-NPs exhibits highly active and efficient performance in the removal of toxic methylene blue (MB) (up to 99.8 %) wastewater in 2 min at different concentrations of MB and different pH values. Moreover, except for toxic MB, the other organic dyes including Rhodamine B (RhB), Rhodamine 6G (Rh6G), and Methyl Orange (MO) can also be removed efficiently by the composite. Finally, the easily recovered composite Fe3O4-lignin@Pd-NPs exhibits well stability and reusability, and catalytic efficiency is maintained well after ten cycles. In conclusion, the lignin-based magnetism Pd composite exhibits powerful potential practical application in industrial wastewater treatment.

Dye removal with emulsion liquid membrane: experimental design and response surface methodology

This work aims to removing anionic food dyes, Acid Red18 (E124) and Quinoline Yellow WS (E104), from their aqueous solutions. The Emulsion Liquid Membrane (ELM) technique was used. ELM consists of diluent (kerosene), nonionic surfactant (0.5 wt. % Triton X-45), Aliquat 336 as an extractant. Sulfuric acid (H2SO4) solution was used as an internal aqueous phase. The key parameters impacting the stability of liquid membrane and the efficiency of dye removal were investigated; Almost 98% of E124 at 50 mg/L are successfully extracted under optimum conditions. The extraction of a mixture of the two dyes at equal concentrations (25 mg/L) was conducted and their extraction showed more than 95% of efficiency. The experimental results of dye mixture (E124, E104) extraction were expressed by the following three quantities: The concentration of Triton X-45, the concentration of Aliquat 336, and the internal phase concentration of H2SO4, represented on three dimensional plots using the Box-Behnken design and the response surface methodology. For each of the parameters, the values of which were determined by experimental design, these results were subjected to empirical smoothing. The values, thus calculated, are consistent with the measurements.

"Adsorptive removal of Congo Red dye from its aqueous solution by Ag-Cu-CeO2 nanocomposites: Adsorption kinetics, isotherms, and thermodynamics"

Eliminating synthetic dyes and organic contaminants from water is crucial for safeguarding human health and preserving the environment. In this study, we explored the effectiveness of Ag-Cu-CeO2 nanocomposites as adsorbents to remove Congo Red dye from water. Three compositions of Ag-Cu-CeO2 nanocomposites (10:20:70, 15:15:70, and 20:10:70) have been synthesized by the aqueous coprecipitation method. A comprehensive analysis was performed by different techniques including X-ray diffraction, Fourier transform infrared spectroscopy, BET surface area determination, Thermogravimetric analysis, Scanning electron microscopy, and TEM. The synthesized nanocomposites have a dimension of 5 ± 1 nm and a high surface area (51.832-78.361 m2g-1). Among these, the nanocomposite with composition 15:15:70 showed the highest adsorption capacity of 4.71 mg/g adsorption (96.83 % removal) from the 0.8 × 10-4 M (55.6 mg/l) Congo Red solution at pH values of 2 at 20 °C with contact time of 3h. The adsorption data is best fitted in the Freundlich adsorption isotherm and pseudo-second-order kinetic model. The negative values of enthalpy variation (-27.57, -26.43, and -16.73 kJ/mol) demonstrated that the adsorption was spontaneous and exothermic. The cycling run showed a mere 12 % deactivation after five cycles of use thus indicating that Ag-Cu-CeO2 nanocomposites hold great potential as effective and eco-friendly adsorbents to remove Congo Red from water.

Synthesis and application of manganese-doped zinc oxide as a potential adsorbent for removal of Congo red dye from wastewater

Synthetic dyes are considered toxic compounds and as such are not easily removed by conventional water treatment processes. This study demonstrated the synthesis of pure and manganese- (Mn), silver- (Ag), and iron- (Fe) doped zinc oxide (ZnO) nanoparticles via the wet chemical route. In particular, it investigated the batch adsorption studies and physiochemical properties of synthesized pure and doped ZnO materials for removing toxic congo red (CR) dye. X-ray diffraction (XRD), Raman spectroscopy, and energy-dispersive X-ray spectroscopy (EDS) confirmed the synthesis of the pure and doped ZnO materials. The batch adsorption investigation revealed adsorption efficiencies of 99.4% for CR dye at an optimal dose of 0.03 g/30 ml for Mn-doped ZnO at a solution pH of 2. The adsorption capacity of each of the synthesized materials was found to be in order Mn-doped ZnO (232.5 mg/g) > Ag-doped ZnO (222.2 mg/g) > pure ZnO (212.7 mg/g) > Fe-doped ZnO (208.3 mg/g). Both pseudo-second-order kinetics model and the Langmuir isotherm model accurately explained the adsorption behaviors of CR dye. As such, Van der Waal interactions, H-bonding, and electrostatic interaction were found to be the adsorption mechanisms responsible for dye removal. In addition, the desorption-regeneration investigation indicated the successful reuse of the exhausted Mn-doped ZnO material for five cycles of CR dye adsorption with an efficiency of 83.1%. Overall, this study has demonstrated that Mn-doped ZnO could be considered a viable adsorbent for the cleanup of dye-contaminated water.

Optimization of LDO-Pectin Synthesis Conditions for the Removal of Metals from Wastewater: A Comparison of Response Surface Methods and Taguchi Approaches

With the continuous growth of industrialization, the presence of heavy metals (HMs) in the environment has become a critical issue, necessitating cost-effective and efficient techniques for their removal. The present study aimed to determine the optimal preparation conditions for synthesizing pectin (PC) as a polymer sorbent, combined with Magnesium (Mg) Aluminum (Al) layered double oxides (LDOs), using a fast and facile co-precipitation method. Both the response surface method (RSM) and the Taguchi method were employed to optimize the influence of key independent variables, including the molar ratio of cations Mg:Al, the ratio of pectin to LDO, and the temperature for removing multiple elements from wastewater. The results indicated that RSM is more accurate and examines more interactions, while Taguchi reduces the number of tests and is more economical than RSM. However, both statistical methods showed good potential for predicting the adsorption capacity (Qe) of HMs. The optimal preparation conditions were identified as a molar ratio of 3:1, a ratio of pectin to LDO of 7% w/w, and a temperature of approximately 600 °C. In conclusion, the application of RSM and Taguchi approaches was found to be feasible and effective in optimizing the preparation conditions of modified LDO, which can be utilized as a potential adsorbent for removing multiple elements from wastewater.

Application of dewatered paper sludge-derived porous solid base catalyst for biodiesel production: Physicochemical properties, reaction kinetics and thermodynamic studies

A new porous solid base catalyst was prepared using dewatered paper sludge and successfully employed to produce biodiesel from soybean oil. The as-prepared catalyst was characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transforms infrared spectroscopy, X-ray photoelectron spectroscopy, thermal gravity/differential thermal gravity analysis, Brunauer-Emmet-Teller analysis, and CO2-temperature programmed analysis. The results showed that the formation of CaO and uniformly distributed porous structure should account for the high catalytic activity of the as-prepared catalyst. The optimum reaction conditions were observed at 180 ℃, 8 wt.% catalyst/oil weight ratio, 16:1 methanol/oil molar ratio, and 300 min reaction time with 91.6% biodiesel yield. After being used several times and recycled, the regenerated catalyst still exhibited effective catalytic activity without apparent deactivation. The kinetic study confirmed that the experimental data satisfied with Pseudo-first-order kinetic model controlled by reaction temperature and catalyst/oil weight ratio. The reaction activation energy was 24.98 kJ/mol. The change of enthalpy ΔH (14.98 kJ/mol), entropy ΔS (-208.57 J/mol/K), and Gibbs free energy ΔG (109.46 kJ/mol) indicated that the transesterification reaction catalyzed by the dewatered paper sludge-derived catalyst is endothermic, endergonic, and non-spontaneous. Our research finding indicated that the CaO-based catalyst derived from dewatered paper sludge was an economically promising and eco-friendly solid base catalyst for biodiesel production.

Preparation of sisal fiber/polyaniline/bio-surfactant rhamnolipid-layered double hydroxide nanocomposite for water decolorization: kinetic, equilibrium, and thermodynamic studies

Sisal fiber is a potent economical biomaterial for designing composites because of its low density, high specific strength, no toxic effects, and renewability. The present study utilized sisal fiber as a starting material and subjected it to modification to produce a sisal fiber/polyaniline/bio-surfactant rhamnolipid-layered double hydroxide nanocomposite material denoted as SF@PANI@LDH@RL. The composite was evaluated for its efficacy in removing reactive orange 16 (RO16) and methylene blue (MB) from aqueous solutions. The synthesized adsorbent was characterized by FTIR, XRD, and SEM-EDS techniques; these analyses indicated the successful modification of the sisal fiber. The primary factors, including contact time, adsorbent dosage, dye concentration, temperature, and pH, were optimized for achieving the most excellent adsorption efficiency. On the one hand, methylene blue removal is enhanced in the basic solution (pH = 10). On the other hand, reactive orange 16 adsorption was favored in the acidic solution (pH = 3). The highest adsorption capacities for methylene blue and reactive orange 16 were 24.813 and 23.981 mg/g at 318 K, respectively. The Temkin isotherm model, which proves the adsorption procedure of methylene blue and reactive orange 16 could be regarded as a chemisorption procedure, supplies the most suitable explanation for the adsorption of methylene blue (R² = 0.983) and reactive orange 16 (R² = 0.996). Furthermore, Elovich is the best-fitting kinetic model for both dyes (R² = 0.986 for MB and R² = 0.987 for RO16). The recommended SF@PANI@LDH@RL adsorbent was reused six consecutive times and showed stable adsorption performance. The results demonstrate that SF@PANI@LDH@RL is a perfect adsorbent for eliminating cationic and anionic organic dyes from aqueous media.

Comprehensive evaluation of zeolite/marine alga nanocomposite in the removal of waste dye from industrial wastewater

A systematic study integrating laboratory, analytical, and case study field trial was conducted to figure out the effective adsorbent that could be used for the removal of Congo red (CR) dye from industrial wastewater effluent. The ability of the zeolite (Z) to adsorb CR dye from aqueous solutions was evaluated after it was modified by the Cystoseira compressa algae (CC) (Egyptian marine algae). Zeolite, CC algae were combined together in order to form the new composite zeolite/algae composite (ZCC) using wet impregnation technique and then characterized by the aid of different techniques. A noticeable enhancement in the adsorption capacity of newly synthesized ZCC was observed if compared to Z and CC, particularly at low CR concentrations. The batch style experiment was selected to figure out the impact of various experimental conditions on the adsorption behavior of different adsorbents. Moreover, isotherms and kinetics were estimated. According to the experimental results, the newly synthesized ZCC composite might be applied optimistically as an adsorbent for eliminating anionic dye molecules from industrial wastewater at low dye concentration. The dye adsorption on Z and ZCC followed the Langmuir isotherm, while that of CC followed the Freundlich isotherm. The dye adsorption kinetics on ZCC, CC, and Z were agreed with Elovich, intra-particle, and pseudo-second-order kinetic models, correspondingly. Adsorption mechanisms were also assessed using Weber's intraparticle diffusion model. Finally, field tests showed that the newly synthesized sorbent has a 98.5% efficient in eliminating dyes from industrial wastewater, authorizing the foundation for a recent eco-friendly adsorbent that facilitate industrial wastewater reuse.

Pyrolyzed magnetic NiO/carbon-derived nanocomposite from a hierarchical nickel-based metal-organic framework with ultrahigh adsorption capacity

Herein, a simple one-pot solvothermal approach is used to create magnetic porous carbon nanocomposites which obtained from a nickel-based metal-organic framework (Ni-MOF) and examined for their ability to uptake methyl orange (MO) dye. Derived carbons with exceptional porosity and magnetic properties were created during the different pyrolysis temperatures of Ni-MOF (700, 800, and 900 °C) under a nitrogen atmosphere. The black powders were given the names CDM-700, CDM-800, and CDM-900 after they were obtained. A variety of analysis methods, including FESEM, EDS, XRD, FTIR, VSM, and N₂ adsorption-desorption were used to characterize as-prepared powders. Furthermore, adsorbent dosage, contact time, pH variation, and initial dye concentration effects was investigated. The maximum adsorption capacities were 307.38, 5976.35, 4992.39, and 2636.54 mg/g for Ni-MOF, CDM-700, CDM-800, and CDM-900, respectively, which show the ultrahigh capacity of the resulted nanocomposites compared to newest materials. The results showed that not only the crystallinity turned but also the specific surface area was increased about four times after paralyzing. The results showed that the maximum adsorption capacity of MO dye for CDM-700 was obtained at adsorbent dosage of 0.083 g/L, contact time of 60 min, feed pH of 3, and temperature of 45 °C. The Langmuir model has the best match and suggests the adsorption process as a single layer. According to the results of reaction kinetic studies using well-known models, the pseudo-second-order model (R² = 0.9989) displayed high agreement with the experimental data. The synthesized nanocomposite is introduced as a promising superadsorbent for eliminating dyes from contaminated water due to strong recycling performance up to the fifth cycle.

Adsorption of Rhodamine B from an aqueous solution by acrylic-acid-modified walnut shells: characterization, kinetics, and thermodynamics

A batch experiment was used in studying the effect of acrylic-acid-modified walnut shell (MWNS) as a low-cost adsorbent for removing Rhodamine B (RB) cationic dye in aqueous solutions. The adsorbent dosage, initial dye concentration, contact time, temperature, pH, and supporting electrolyte concentration on the adsorption behaviour of the adsorbent were explored. The adsorbent was characterized using the point of zero charge (pH_PZC), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), automatic specific surface analysis (BET), and X-ray photoelectron spectroscopy (XPS). Results showed that MWNS had abundant active groups and rough surface, which is conducive to the adsorption process. The kinetics and equilibrium data of MWNS-to-RB adsorption were in accordance pseudo-second-order kinetic and Freundlich isotherm models, respectively. Under optimal adsorption conditions, the maximum adsorption capacity of RB was 48.87 mg·g^-1. Thermodynamic results showed spontaneously and exothermically the adsorption process. Moreover, the addition of electrolyte had a negative effect on equilibrium adsorption capacity and adsorption rate.HIGHLIGHTS Acrylic-acid-modified walnut shells was used as an adsorbent for the removal of Rhodamine B (RB).The adsorption of RB by modified walnut shells was greatly affected by pH.Pseudo-second-order kinetic and Freundlich model fit the experimental data.The modified walnut shell can remove RB through electrostatic attraction, hydrogen bonding, and electron donor-acceptor interaction.

Modeling of methylene blue removal on Fe3O4 modified activated carbon with artificial neural network (ANN)

In this study, AC/Fe3O4 adsorbent was first synthesized by modifying activated carbon with Fe3O4. The structure of the adsorbent was then characterized using analysis techniques specific surface area (BET), Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDX), and Fourier Transform Infrared Spectroscopy (FTIR). Equilibrium, thermodynamic and kinetic studies were carried out on the removal of methylene blue (MB) dyestuff from aqueous solutions AC/Fe3O4 adsorbent. The Langmuir maximum adsorption capacity of AC/Fe3O4 was 312.8 mg g-1, and the best fitness was observed with the pseudo-second-order kinetics model, with an endothermic adsorption process. In the final stage of the study, the adsorption process of MB on AC/Fe3O4 was modeled using artificial neural network modeling (ANN). Considering the smallest mean square error (MSE), The backpropagation neural network was configured as a three-layer ANN with a tangent sigmoid transfer function (Tansig) at the hidden layer with 10 neurons, linear transfer function (Purelin) the at output layer and Levenberg-Marquardt backpropagation training algorithm (LMA). Input parameters included initial solution pH (2.0-9.0), amount (0.05-0.5 g L-1), temperature (298-318 K), contact time (5-180 min), and concentration (50-500 mg L-1). The effect of each parameter on the removal and adsorption percentages was evaluated. The performance of the ANN model was adjusted by changing parameters such as the number of neurons in the middle layer, the number of inputs, and the learning coefficient. The mean absolute percentage error (MAPE) was used to evaluate the model's accuracy for the removal and adsorption percentage output parameters. The absolute fraction of variance (R2) values were 99.83, 99.36, and 98.26% for the dyestuff training, validation, and test sets, respectively.

Secondary bond interface assembly of polyethyleneimine on zein microparticles for rapid adsorption of Reactive Black 5

Textile dye wastewater has the characteristics of high concentration, complex composition and changeable color degree and pH, which is difficult to be effectively and completely treated, and easy to cause environmental pollution. Here, a strategy of secondary bond interface assembly of polyethyleneimine on zein microparticles (PEI) (PEI@zein) was constructed to achieve rapid and efficient removal of Reactive Black 5 (RB5), which is one of the most widely used reactive dyes in the textile industry. Structural analysis indicated that the as-prepared PEI layer immobilized on zein microparticles was constructed based on the interface assembly dominated by hydrophobic interactions and electrostatic attraction between PEI molecules and zein chains. The novel interface showed excellent absorption performance for RB5 with an absorption capacity of 631.0 mg·g^-1, rapid adsorption in 2 min, wide pH range of 4-10. Mechanism analysis suggested the effective adsorption of RB5 by PEI@zein microparticles was mainly attributed to secondary bond interface such as electrostatic interaction and hydrogen bond between RB5 and PEI immobilized on the surface of zein microparticles. Moreover, due to the presence of secondary bond interface, RB5 adsorbed on microparticles can be easily desorbed by using 0.01 M NaOH. Therefore, the strategy of secondary bond interface assembly with polyethyleneimine on zein microparticles has high potential for practical application in the treatment of dye-containing wastewater.

Origanum vulgare manganese ferrite nanocomposite: An advanced multifunctional hybrid material for dye remediation

The purpose of the study was to fabricate sustainable and cost-effective material for the thorough cleansing of polluted water. In this context, an economical, phytogenic and multifunctional Origanum vulgare plant-based nanocomposite material, MnFe₂O₄/OV, was prepared via one-pot synthetic technique. The synthesized nanocomposite with a band gap of 2.02 eV behaved as an efficient nano-photocatalyst for the degradation of both cationic (crystal violet) and anionic (congo red) dyes under direct sunlight irradiation. The material also inhibited the growth of E. coli and S. aureus bacteria and simultaneously adsorbed both cationic and anionic dyes from water through adsorption. A variety of techniques have been used to characterize the nanocomposite, including X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM). Additionally, the kinetics of photodegradation of the aforementioned organic dyes has also been investigated. The MnFe₂O₄/OV exhibited excellent photocatalytic performance, leading to 43% and 72% degradation within 3 h at rate constants of 2.0 × 10^-3 min^-1 and 6.0 × 10^-3 min^-1 for crystal violet and congo red, respectively. The crystal violet and congo red were used to testify to the composite's potential for adsorption under the influence of several process variables, including initial solution pH, contact time, temperature, initial dye concentration, and amount of MnFe₂O₄/OV. The Langmuir maximum adsorption capacity Q_max as in the range 14.06-14.59 mgg^-1 for crystal violet and 34.45-23.93 mgg^-1 for congo red at pH 7 within 90 min contact time in the temperature range of 30-50 °C. The phenomenon of adsorption was found feasible and endothermic at all the investigated temperatures. Also, E. coli and S. Aureus bacteria have shown growth suppression activity when exposed to MnFe₂O₄/OV.As a result, the synthesized nanocomposite, MnFe₂O₄/OV, proved to be an antimicrobial, multifunctional novel nanocomposite, which is in high demand, and could serve as an affordable, and sustainable material for comprehensive water filtration.

Tropical fruit wastes including durian seeds and rambutan peels as a precursor for producing activated carbon using H3PO4-assisted microwave method: RSM-BBD optimization and mechanism for methylene blue dye adsorption

Herein, tropical fruit biomass wastes including durian seeds (DS) and rambutan peels (RP) were used as sustainable precursors for preparing activated carbon (DSRPAC) using microwave-induced H3PO4 activation. The textural and physicochemical characteristics of DSRPAC were investigated by N2 adsorption-desorption isotherms, X-ray diffraction, Fourier transform infrared, point of zero charge, and scanning electron microscope analyses. These findings reveal that the DSRPAC has a mean pore diameter of 3.79 nm and a specific surface area of 104.2 m2/g. DSRPAC was applied as a green adsorbent to extensively investigate the removal of an organic dye (methylene blue, MB) from aqueous solutions. The response surface methodology Box-Behnken design (RSM-BBD) was used to evaluate the vital adsorption characteristics, which included (A) DSRPAC dosage (0.02-0.12 g/L), (B) pH (4-10), and (C) time (10-70 min). The BBD model specified that the DSRPAC dosage (0.12 g/L), pH (10), and time (40 min) parameters caused the largest removal of MB (82.1%). The adsorption isotherm findings reveal that MB adsorption pursues the Freundlich model, whereas the kinetic data can be well described by the pseudo-first-order and pseudo-second-order models. DSRPAC exhibited good MB adsorption capability (118.5 mg/g). Several mechanisms control MB adsorption by the DSRPAC, including electrostatic forces, π-π stacking, and H-bonding. This work shows that DSRPAC derived from DS and RP could serve as a viable adsorbent for the treatment of industrial effluents containing organic dye.

Statistically optimized sequential hydrothermal route for FeTiO3 surface modification: evaluation of hazardous cationic dyes adsorptive removal

In the present study, the performance of facile hybrid sequential chemical treatments of titanomagnetite concentrate (TC), alkaline leaching, and sodium dodecyl sulfate (SDS) modification has been evaluated for the removal of crystal violet (CV), malachite green (MG), and methylene blue (MB) cationic dyes. The physical and chemical properties of samples were characterized using scanning electron microscopy (SEM), energy dispersive X-ray (EDX), N₂ adsorption-desorption, X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), and Fourier transform infrared spectroscopy (FTIR) analyses. Moreover, dye removal in the batch system was investigated by evaluating adsorbent dosage, contact time, initial dye concentration, pH of the solution, temperature, electrolyte concentration, adsorption isotherm, kinetic, and thermodynamic. The results showed that the maximum adsorption capacity was obtained at SDS concentration of 6 mM, NaOH concentration of 9 M, the temperature of 160 °C, solid/liquid ratio of 4 g/100 mL, and the process duration of 24 h. In the alkaline leaching process, forming the Na₂TiO₃ phase with sharp and high energy points can be improved the adsorption properties. Accordingly, the adsorption capacity and removal efficiency attained 19.84, 18.64, and 19.66 mg/g and 99.21, 93.24, and 98.31% for CV, MG, and MB, respectively. Furthermore, the dye removal followed pseudo-second-order (R² = 0.9990) and Freundlich (R² = 0.9970) models. The evaluation of thermodynamic parameters indicated the endothermic (∆H° = 110.91 J/mol) and spontaneous nature (ΔG˚ < 0) of the adsorption process. This study concluded that the modified TC had a potential ability for application in textile wastewater treatment.

Removal of methylene blue dye from aqueous solution using an efficient chitosan-pectin bio-adsorbent: kinetics and isotherm studies

Wastewater contains organic compounds, including dyes, which have potential risks to the environment. Hence, these compound needs to be eliminated from the aqueous solution. In the present study, chitosan-pectin composite (Cs-Pc) was used as an adsorbent to remove methylene blue dye (MB) from synthetic wastewater. To evaluate the parameters affecting adsorption, including the initial MB concentration, solution pH, contact time, and Cs-Pc dose, batch experiments were carried out. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared (FTIR), and pH point of zero charges (pH pzc) were applied for characterizations of Cs-Pc. The optimum conditions were obtained with an initial MB concentration of 50 mg L^-1: solution pH ~ 11, Cs-Pc dose: 1.5 g L^-1 and 180 min contact time, which caused 97.77% of MB removal. In addition, the removal efficiency of MB was more influenced by pH than by sorbate dose. Also, Cs-Pc had a higher ability to remove MB than chitosan and pectin, probably due to its highly porous structure and rough surfaces that provides active sites and facilitate MB adsorption. The maximum removal efficiency and the adsorption capacity of MB onto Cs-Pc at 500 mg L^-1 concentration under optimum conditions were 98.67% and 328.02 mg g^-1, respectively. The adsorption kinetics and isotherms were best described by pseudo-second-order and Freundlich equation, respectively. After four times of recycling, the removal efficiency of MB was above 96%. Electrostatic and pi-pi interactions are the main mechanisms for the removal of MB onto the adsorbent. So the application of Cs-Pc is promising for MB removal from polluted solutions not only due to its strong adsorbing capability but also due to its excellent ability to reuse.

Effect of three aging processes on physicochemical and As(V) adsorption properties of Ce/Mn-modified biochar

Modified biochar used for soil remediation is affected by exposure to the environment and aging process results in changes in its physicochemical properties and As(V) adsorption and immobilization in soil. Herein, the Ce/Mn-modified wheat straw-biochar (MBC) was manufactured and then aged through three artificial aging processes by exposure to soil with additional natural, freeze-thaw, and dry-wet cycles involved. It revealed that the specific surface areas of freeze-thaw-aged MBC reached 214.98 m²/g and was increased more than those of other two aging treatments. In addition, the pH values and C contents of MBC all decreased after aging while the H and O contents increased. Correspondingly, the contents of O-containing functional groups like C-O, -OH, and CO all increased by >16% with aging. The freeze-thaw cycling and alternating dry-wet aging treatments improved adsorption capacities of As(V) onto MBC and were increased by 16.2 and 10.6% at pH 5, respectively and these samples exhibited the best recyclability and adsorption selectivity for As(V). However, natural aging exerted a lower effect for As(V) adsorption by MBC due to its few changes on physicochemical properties. Causally, the freeze-thaw and dry-wet aging activated the Ce/Mn-oxides to generate Mn^2+/3+ species and a new mono-Ce that exerted a strong bonding complexation with As(V) to form Ce/Mn-O-As ligands and increased CeAsO₄ precipitation. Our results offer a new insight into the alterations expected for modified biochars with aging treatment in terms of As(V) adsorption for its long-term utilization in As contaminated soil.

Methylene blue removal using raw and modified biomass Plumeria alba (white frangipani) in batch mode: isotherm, kinetics, and thermodynamic studies

Hazardous dyes used in textile industries are considered high-risk pollutants to the environment. The raw as well as acid-treated Plumeria alba (white frangipani) leaf powder (WFLP and SWFLP) were used for the adsorption of methylene blue (MB) that is available in industrial wastewaters following the batch adsorption technique. The characterizations of adsorbents were done by FTIR, SEM, EDX, TGA, and zeta potential parameters. The adsorption was considered for the effects of temperature, initial dye concentration, solution pH, adsorbent dosage, and contact time. The experimental results obtained in the adsorption of MB were examined by nonlinear error functions like chi-square (χ²), ARE, and MPSD for three isotherm models: Langmuir, Freundlich, and Temkin. The maximum monolayer adsorption capacity, q_max (mg/g), was 45.45 mg/g for raw WFLP and 250 mg/g for SWFLP. The adsorbents fitted to the pseudo-second-order kinetic model (R² = 0.99) using the experimental data of batch adsorption. The thermodynamic studies explained the spontaneity and nature of adsorption for raw and acid-treated adsorbents. The batch experimental results and characterizations of the adsorbents revealed that the selected adsorbents would be the best adsorbents for the removal of MB from the wastewater solution.

A Generalized Method for the Synthesis of Carbon-Encapsulated Fe3O4 Composites and Its Application in Water Treatment

In this paper, a simple and environmentally friendly method was developed for the preparation of highly stable C@Fe₃O₄ composites with controllable morphologies using sodium alginate as the carbon source and the easily obtained α-Fe₂O₃ as the precursors. The morphologies of the as-prepared C@Fe₃O₄ composites, inherited from their corresponding precursors of α-Fe₂O₃, survived from the annealing treatments, were characterized by the field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The C@Fe₃O₄ composites resisted to oxidation, acidification and aggregation, exhibiting porous structures and ferromagnetic properties at room temperature. Moreover, the adsorption performance of the C@Fe₃O₄ composites was evaluated by absorbing MB (methylene blue) in liquid environment. Experiments indicated that the C@Fe₃O₄ composites exhibited highly enhanced adsorption capacities and efficiencies as compared with their corresponding precursors of α-Fe₂O₃. This generalized method for the synthesis of C@Fe₃O₄ composites provides promising applications for the highly efficient removal of MB from industrial effluents.

Carbon Nanotubes/Polydopamine/ZSM-5 Composite Soil Conditioner with Good Controlled Release and Adsorption Properties

Currently, the excessive application of fertilizers and the random discharge of waste water, waste gas, and residues have led to more and more serious soil pollution problems. Zeolite is the most promising material for preparing a green and environmentally friendly soil conditioner. Herein, the carbon nanotubes/polydopamine/ZSM-5 composite soil conditioner was prepared by a facile two-step method, and it was used to release fulvic acid and adsorb methylene blue to improve the environment. The cumulative release rate of the composite soil conditioner was 52% within 430 h for fulvic acid, which had a good sustained release effect and could be sustained-released in different acid-based surroundings. In addition, it showed a good adsorption capacity of methylene blue, and it is about 80.02 mg/g which was about six times higher than that of ZSM-5. It was beneficial for the adsorption of methylene blue in a neutral environment. Finally, it could promote the growth of brassica chinensis and maize, and the promotion effect was 60 and 35%, respectively. Therefore, the carbon nanotubes/polydopamine/ZSM-5 composite soil conditioner is a green and efficient material, which provides a new strategy to solve the problem of soil pollution.

Adsorption of Safranin-O dye by copper oxide nanoparticles synthesized from Punica granatum leaf extract

The development of new technologies for water and wastewater treatment is a growing need due to the occurrence of micropollutants, such as dyes, in water resources. In this sense, green-synthesized nanoparticles are being extensively studied, due to their low cost, non-toxicity, and high efficiency in adsorption processes. Thus, the present study reports the green synthesis of copper oxide nanoparticles (CuO-NP), obtained from pomegranate (Punica granatum) leaf extract, employed for the removal of Safranin-O (SO) dye. CuO-NP was characterized by physicochemical analysis. These analyzes suggested that the redox process occurred efficiently. Also, the material presented interesting elements for the removal of cationic dyes such as negative surface charge, high specific surface area, and predominance of mesopores. The kinetic data fitted the pseudo-second-order model, reaching equilibrium in 480 min. The equilibrium study resulted in a maximum adsorption capacity of 189.54 mg g^-1 at 298 K and the experimental data best fitted the Langmuir model. The effect of pH and ionic strength did not present significant changes, which demonstrates an advantage of this adsorbent over other materials. The regeneration study allowed to verify the possibility of reuse CuO-NP, since after 4 cycles the adsorption capacity was 44% of the initial value. Considering the results found, CuO-NP has a high potential for applicability in the treatment of water contaminated by dyes.

Characterization and adsorption of malachite green dye from aqueous solution onto Salix alba L. (Willow tree) leaves powder and its respective biochar

In the present study, the use of low-cost, highly efficient, eco-friendly, and abundantly available (in Kashmir region, J&K India) willow leaves from which adsorbents like willow leaves powder (WLP) and willow leaves biochar (WLB) were prepared, have been found to be efficient for malachite green (MG) dye removal and can be used as an alternative to the current expensive methods of removing the same dye from an aqueous solution. The techniques like Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), and carbon, hydrogen, nitrogen, sulphur (CHNS) analyser were used to characterize the samples without any chemical treatment. SEM of the adsorbents shows the presence of different sized pores, cracks, and crevices. FTIR and CHNS show functional groups and elemental concentration, respectively. The effects of various experimental parameters such as contact time, adsorbent dosage, initial dye concentration, salt treatment, and pH were investigated and optimal experimental conditions were obtained. It has been found that Langmuir, Freundlich, and Temkin isotherms were useful for describing the equilibrium of adsorption system. The equilibrium adsorption data in this research work was found to follow both Langmuir and Freundlich isotherm models and maximum monolayer capacity of WLP and WLB were found to be 10.014 and 21.244 mg/g, respectively. The experimental data for both WLP and WLB followed pseudo-second-order kinetic model with R²= 0.999. Intraparticle diffusion model reveals that more than one mechanism influenced the adsorption process. Thermodynamic study concluded that the adsorption is spontaneous for both adsorbents but exothermic for WLP and is endothermic in nature for WLB. Present exploration and comparison with other reported adsorbents concluded that, WLP and WLB may be useful as low-cost attractive option for the removal of MG dye from aqueous solution and therefore, also from wastewater containing MG dye.

Adsorptive Behavior of Tartaric Acid Treated Holarrhena antidysenterica and Citrullus colocynthis Biowastes for Decolourization of Congo Red Dye from Aqueous Solutions

The aim of the present work is to eradicate Congo red (CR) dye from aqueous solutions since the dye compounds are harmful to human life and the environment leading to detrimental results. For this purpose, Holarrhena antidysenterica (HA) and Citrullus colocynthis (CC) adsorbents were used for the adsorptive removal of Congo red dye from wastewaters. The unmodified adsorbents (U-HA and U-CC) were chemically modified using tartaric acid (TA). Morphological structures were examined by FTIR and SEM. Batch adsorption studies were tested at a variety of pH, time exposure, temperatures, and adsorbent dosages. Thermodynamic parameters such as Gibbs free energy ( $∆G^{°}$ ), enthalpy ( $∆H^{°}$ ), entropy changes ( $∆S^{°}$ ), and energy of activation ( $E_{\text{a}}$ ) were also calculated. The results revealed that tartaric acid-Citrullus colocynthis (TA-CC) gave optimum conditions of time of contact (35 min), temperature conditions (40°C), pH (3), and dosage of adsorbent (1.6 g) for maximum dye removal. Tartaric acid-Holarrhena antidysenterica (TA-HA) gave equilibrium time of contact (30 min), temperature (40°C), and pH optimum (2) along with a 1.6 g dosage of adsorbent. Mechanistic understanding of adsorption isotherm provided that the Langmuir model was followed by raw and modified adsorbents. Maximum adsorption capacities $Q_{\max }$ attained were 60.61 (mg g-1), 128.21 (mg g-1), 87.71 (mg g-1), and 131.57 (mg g-1), respectively, for U-HA, TA-HA, U-CC, and TA-CC. The results of kinetic modeling displayed a high value of $R^2$ (0.99) along with minimal error (RMSE) for dye removal showing that the pseudo-second-order kinetic model has acceptable accuracy. Fourier transform infrared proposed the electrostatic, pi-pi interactions, and hydrogen bonding as dominant adsorption mechanisms at acidic pH, respectively. Rate-determining steps comprise both surface and intraparticle diffusions. Thermodynamics indicated that the dye adsorption of CR is spontaneous, exothermic, and favorable in nature. These agricultural wastes due to specific points such as low cost, availability, and high removal rates of adsorption are highly competent for the expulsion of anionic dye like CR from wastewaters.

Evaluating cottonwood seeds as a low-cost biosorbent for crystal violet removal from aqueous matrics

In this study, cottonwood seeds (CWS) were introduced as a novel, green, and low-cost biosorbents for the removal of crystal violet (CV) dye from aqueous solutions. To illustrate the characteristics of CWS, surface morphology, Fourier-transform infrared spectroscopy, field emission scanning electron microscopes, and energy dispersive X-ray spectroscopy techniques were employed. Important adsorption variables (i.e., equilibrium time, solution pH, CWS amount, CV concentration, and temperature) were systematically studied. Maximum CV dye adsorption was observed at pH 10 using 20 mg of the adsorbent. Different adsorption isotherms were investigated, and the results were more accurately consistent with the Langmuir model (R² = 0.992). The maximum capacity of adsorption was 153.85 mg g^-1 at 60 min. The kinetic data were examined by different models and a pseudo-second-order model supplied the best correlation between experimental data. Investigated thermodynamic parameters at different temperatures illustrated that the CV adsorption procedure was spontaneous and endothermic with an increase in entropy. The percentage removal and the relative standard deviations for the real sample analysis were in the range of 89-98% and 4.9-9.5%, respectively. High adsorption capacity and low equilibrium time demonstrated that CWS is an impressive biosorbent for dye pollutants uptakes from aqueous solutions and real industrial wastewater samples.

Preparation and characterization of low-cost nano-particle material using pomegranate peels for brilliant green removal

A low-cost nano-particle material was successfully prepared using waste pomegranate peels. Batch adsorption experiments were carried out to investigate the effect of different operating conditions on the removal of brilliant green (BG) dye from an aqueous solution. SEM images of pomegranate peels nano-particles (PPNP) declared roughness of the surfaces and TEM images indicated a spheroid shape with an average particle size of 37 nm. The specific surface area of the PPNP was 354.46 m²/g and the particle size had a mean diameter of 613.4 nm. The active nano-particle suspension showed a net negative charge (-29 mV) at natural pH. The XRD pattern of PPNP displayed an average crystallite size of 13.50 nm and EDS analysis shows that the PPNP consists of 83% carbon. The experimental work showed that the removal of BG had optimum removal efficiency at 20 min, 0.3 g adsorbent mass, 25 °C, and pH 8. The kinetic data can be described well with the pseudo-second-order model and the isotherm data was found to fit the Dubinin model. The thermodynamic study proved that BG adsorption on PPNP was physisorption (ΔG = -5.949 kJ/mol) and spontaneous at low temperature (ΔH = -17.193 kJ/mol, ΔS = -0.0382 kJ/mol. k)This study used an agriculture waste (pomegranate peels) to prepare an environmentally friendly and low-cost adsorbent within the nano-scale by thermal activation. The nano-particles prepared were shown to be a promising adsorbent, demonstrating high surface area and well-developed porosity. The prepared adsorbent will have a great impact on wastewater treatment technology and possible applications at a large scale.

Fabrication of biochar-based hybrid Ag nanocomposite from algal biomass waste for toxic dye-laden wastewater treatment

Dual functional innovative approaches were developed to tackle the algal scum problem in water by utilizing the algal (Spirogyra sp.) biomass waste for organic dye-laden industrial wastewater treatment, a global problem, and challenge. Therefore, an algal biochar-based nanocomposite (nAgBC) was synthesized and employed as a low-cost adsorbent for Congo red (CR) removal. Surface morphology, physicochemical characteristics, elemental composition, phase, and stability of the nanocomposite was analyzed using BET, FESEM-EDX, FTIR, XRD, XPS, and TGA. The nanocomposite was found to be thermostable, mesoporous with large and heterogeneous surface area, containing nAg as doped material, where -OH, NH, CO, CC, SO, and CH are the surface binding active functional groups. Maximum adsorption efficiency of 95.92% (18 mg L^-1 CR) was achieved (qe = 34.53 mg g^-1) with 0.5 g L^-1 of nanocomposite after 60 min, at room temperature (300 K) at pH 6. Isotherm and kinetic model suggested multilayer chemisorption, where adsorption thermodynamics indicated spontaneous reaction. Fluorescens spectral analysis of CR confirmed the formation of CR supramolecule, supporting enhanced adsorption. Furthermore, the result suggested a 5th cycle reusability and considerable efficacy towards real textile industrial effluents. Synergistic effects of the active surface functional groups of the biochar and nAg, along with the overall surface charge of the composite lead to chemisorption, electrostatic attraction, H-bonding, and surface complexation with CR molecules. Thus, synthesized nAgBC can be applicable to mitigate the wastewater for cleaner production and environment.

Biosorptive removal of crystal violet dye from aqueous solutions by Ficus religiosa leaves and Daucus carota pomace in ecofriendly way

In this study, Ficus religiosa leaves (FRLs) and Daucus carota pomace (DCP) were used effectively for the removal of carcinogenic and non-biodegradable Crystal Violet dye from the aqueous medium on the batch scale as low-cost and environment-friendly biosorbents. Certain experimental conditions such as adsorbent dose, contact time, pH, and temperature were studied for thermodynamic and isothermal data investigations and optimized conditions for F. religiosa leaves and D. carota pomace were: adsorbent dose; 0.8 and 1.8 g, contact time; 30 and 25 min, pH; 9 and 3 and temperature; 70 °C and 30 °C, respectively. Langmuir, Freundlich, Temkin, and D-R isotherms were studied, and the sorption process indicated chemisorption mode is predominant. The same is supported by kinetic investigation of equilibrium data. The maximum adsorption capacity (q_max) for F. religiosa leaves and D. carota pomace was obtained as 2.4 and 27 mg/g, respectively, which showed that D. carota pomace (DCP) is more effective adsorbent than F. religiosa leaves (FRLs) for removal of CV dye. Exothermic nature and intraparticle diffusion mode are more predominant during the removal of CV dye by these biomaterials, which can be recycled using ethanol.[Figure: see text]Novelty statement: Ficus religiosa and Daucus carota biowaste was explored here for removing an anionic dye. This study will be helpful for exploring the waste potential for phytoremediation of toxic substances using indigenous resources in an ecofriendly way.

Preparation of green synthesized copper oxide nanoparticles for efficient removal of lead from wastewaters

Green synthesis is a clean and eco-friendly process in which metal nanoparticles can be produced by the reaction between a metal salt solution and plant organ extract. In the present study, three copper oxide nanoparticles were green synthesized from the leaf extracts of astragalus (Astragalus membranaceus), rosemary (Salvia rosmarinus), and mallow (Malva sylvestris) as predominant plant cover in the study area was characterized. The effectiveness of three green synthesized nanoparticles in the adsorption of lead ions from polluted water was studied. According to the results, the removal efficiencies of the copper oxide nanoparticles synthesized from astragalus (A-CuO-NPs), rosemary (R-CuO-NPs), and mallow leaf extract (M-CuO-NPs) especially at the highest initial concentration of lead (1.5 mM), were 88.4%, 84.9%, and 69.6%, respectively. Probably due to the smooth morphology and more uniform configuration of the M-CuO-NPs, the changes between equilibrium adsorption (q_e) and equilibrium concentration (C_e) were more regular than those of the A-CuO-NPs and R-CuO-NPs. Therefore, the best fit of the data to the Langmuir and Freundlich isotherms belonged to the adsorption of lead onto the M-CuO-NPs. According to the results reported herein, the copper oxide nanoparticles synthesized from different plant covers are efficient adsorption agents for lead from wastewaters solution.