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AbstractIn this study, copper-bismuth oxide/iron oxide (CuBi2O4@Fe3O4) nanocomposites were prepared by microwave-assisted synthesis and used as adsorbents for the adsorptive removal of cadmium from textile wastewater. The pH/volume of buffer solution, mixing type/period and adsorbent dosage were optimized univariately to enhance the removal efficiency of the adsorbent and determined as 1.5 mL of pH 8.0 buffer solution, vortexing for 60s, and 30 mg of CuBi2O4@Fe3O4 nanocomposite material. Following the determination of the optimum parameters, equilibrium adsorption studies were performed at five different initial concentrations of cadmium within the range of 0.50 − 10 mg L−1 in textile wastewater. A matrix-matching calibration strategy was utilized for the accurate and precise quantification of cadmium in the wastewater matrix with a R2 value of 0.9961. The percent removal efficiencies were calculated within the range of 77.2 − 81.5% for the adsorptive removal of cadmium ions from textile wastewater in the equilibrium adsorption experiments. Furthermore, the Langmuir, Freundlich, and Sips adsorption isotherm models were employed for modeling the equilibrium data, and the results showed that all the models fitted well with the experimental data with R2 values higher than 0.99. The simple and efficient batch adsorption process developed was successfully utilized to remove cadmium ions from textile wastewater. [ABSTRACT FROM AUTHOR]

Rapid industrialization has led to significant environmental challenges, including the disposal of effluents with high zinc ion concentrations. This study investigates the use of hydroxyapatite nanoparticles as an adsorbent for Zn (II) ions from aqueous solutions at neutral pH. These nanoparticles are characterized by their high purity, mesoporous structure, and a specific surface area of 60.97 ± .40 m2 g−1. Their thermal stability was confirmed by thermogravimetric analysis, and zeta potential measurements indicated a surface charge close to the isoelectric point. Adsorption experiments showed that the kinetics fit well with the pseudo‐second‐order model, with a rate constant of 2.58 ± .49 min−1 mg−1 and a determination coefficient (R2) of 1.00. Isotherm analyses using Redlich–Peterson, Langmuir, and Freundlich models revealed the highest adsorption capacity and best fitting with the Redlich–Peterson model, showing maximum capacities of 30.36 mg g−1 (linear fitting) and 32.11 mg g−1 (nonlinear fitting). These fits achieved R2 values of .9949 and .9923, respectively, suggesting efficient and reliable adsorption profiles. This research highlights the potential of hydroxyapatite nanoparticles for effective zinc ion removal, supporting their application in sustainable industrial practices and environmental remediation. [ABSTRACT FROM AUTHOR]

Lavender (L) and Rosa damascena (RD) industrial solid by-products were used as biodegradable adsorbents for the removal of the azo dye Acid Orange 7 from aqueous solutions. The equilibrium for the adsorption (1 g of adsorbent, 20 mL aqueous solution of dye, pH 7.05) occurred at the 60 min and at 100 mg/L initial concentration of azo dye. The adsorbed amount of Acid Orange 7 was 1.63 mg/g (81.50% removal efficiency) for L and 1.74 mg/g (87% removal efficiency) for RD at 293 K. The effectiveness of the adsorption increased decreasing the pH medium: for L at pH 1.5, the removal was 1.975 ± 0.08 mg/g (98.75%), and for RD at pH 3.5, it was 1.975 ± 0.08 (98.75%). The removal behavior for Acid Orange 7 fitted the Freundlich model and suggested a diffusion process related to physical adsorption. For the three investigated temperatures (293 K, 303 K, and 313 K) negative values for Gibb's free energy ΔG0 were observed revealing the spontaneous character of the adsorption processes. The observed decrease of ΔG0 (ranging from − 18 to − 21 kJ/mol) implies a physical nature of the adsorption. The post-adsorption L and RD residues were subjected to solid-state cultivation using the fungus Ganoderma resinaceum GA1M yielding mycelium-based biocomposites. The investigations revealed that the biocomposites were free from Acid Orange 7. The approaches presented here demonstrate that L and RD industrial by-products can be successfully applied for the adsorption of Acid Orange 7 while producing harmless mycelium-based biocomposites through solid-state fermentation using G. resinaceum GA1M. [ABSTRACT FROM AUTHOR]

The present work aims to evaluate the applicability of mollusk (Meretrix lusoria) shells as a biosorbent for toxic metal ions (Cd2+ and Pb2+) following the batch mode biosorption procedure. Some well-known analytical methods have been used to characterize the biosorbent such as a scanning electron microscope (SEM), an energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction. The mechanism of metal ion biosorption was examined using various analytical techniques. Therefore, an evaluation of operating factors such as contact time, pH, initial concentration of metal ions, biosorbent dose, and temperature was performed. The results obtained in this investigation indicated that the optimum conditions for the biosorption of Cd+2 and Pb+2 ions are as follows: pH = 6; contact times of 90 min; and the 20 mg/L of initial [M2+]. And a biosorbent dosage of 1.0 g/100 mL for each metal ion solution was also determined. The maximum removal efficiency results were 90.6% for Cd+2 and 91.5% for Pb+2 at pH 6.0. The biosorption isotherm was investigated using three forms of linear equilibrium (Freundlich, Langmuir, and Temkin models). Kinetic studies were also conducted to determine the equilibrium time for the biosorption of the studied metals utilizing the pseudo-second-order, pseudo-first-order, and intraparticle diffusion model. The data indicate that the biosorption kinetics of Cd2+ and Pb2+ follow the pseudo-second-order models. According to the present study, it can be identified that the shell of Meretrix lusoria is a suitable biosorbent for Cd2+ and Pb2+ ions and can contribute to their removal from environmentally polluted water. [ABSTRACT FROM AUTHOR]

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

In this research, the efficiency of Midyat stone modified with sulphuric acid (H2SO4) in the removal of Methyl Orange (MO) from wastewater is evaluated. Various factors such as contact time, initial MO concentration, and adsorbent dosage were investigated to understand their influence on adsorption efficiency. The optimal conditions for MO removal were as follows: initial concentration 300 mg/L, contact time 70 min, adsorbent dosage 0.5 g. The surface properties of modified Midyat stone (MMS) were investigated using methods such as Fourier transform infrared spectroscopy (FT-IR) and Brunauer, Emmett, and Teller (BET). According to the findings, the isotherm data agreed with the Langmuir isotherm model, indicating both chemical sorption and irreversibility potential. The adsorption capacity of MO at 298, 308 and 318 K was calculated to be 50.02, 54.05 and 58.48 mg/g, respectively. In addition, adsorption kinetics data supported the pseudo-second-order (PSO) kinetic model for MO removal. The research identified MMS as a capable and adaptable substance for capturing MO ions from the aqueous environment due to its significant removal capacity, easy availability, and cost-effectiveness. [ABSTRACT FROM AUTHOR]

This study investigates the removal of heavy metals, particularly copper and nickel, from acidic aqueous solutions using the weakly base polymeric chelating resin Dowex M-4195. The research conducts comprehensive cost–benefit and statistical analyses of various kinetic and isotherm adsorption models. The results show that the PSO and general order models provide high accuracy for the Cu2⁺ adsorption kinetics, while the Avrami fractional order model excels for Ni2⁺. In terms of the isotherm models, the Langmuir and Jovanovic models are highly accurate for both metals, with the Toth model being particularly effective for Ni2⁺ due to its ability to account for surface heterogeneity and multi-layer adsorption. This study also reveals that the kinetic adsorption process is more economically beneficial than the isotherm adsorption process, highlighting the importance of model selection for optimizing heavy metal removal. Incorporating circular economy principles, this research emphasizes the sustainability of using regenerable and reusable adsorbents like Dowex M-4195. The findings provide valuable insights for designing efficient adsorption systems, promoting environmental sustainability, and ensuring public health safety. [ABSTRACT FROM AUTHOR]

A novel method has been explored based on the recovery of two industrial wastes V2O5 and phosphogypsum from the fertilizer production industry, which also provide a significant challenge due to their toxicity and environmental impact. To solve the problem of these two harmful wastes, these residues have been transformed into valuable resources, by the elaboration of Nanoparticles vanadate-hydroxyapatite (NPs-HAP/VAP) adsorbent, contributing a sustainable solution without requiring expensive or highly skilled work. This comprehensive investigation explores the adsorption of the reactive red 141 dye (RR 141) on Ca10(VO4) x(PO4)6−x(OH)2, with (xi = 0, 1.5, 3, 4.5, and 6). Using a Centered Composite Design (CCD), several parameters influencing the adsorption process were examined. The optimal adsorption capacity is 50 mg. g-1 under optimal conditions 57.5 mg of the adsorbent dose, 152.5 mgL-1 for the RR 141, pH 8, 92.5 minutes of contact time, and incorporation ratio of 4.5 with an R2 of 0.99. These results reinforce the effectiveness of our chosen CCD model. Kinetic analysis demonstrated a pseudo-order reaction model with an R2˃0.92, while the Sips isotherm describes the adsorption process. Thermodynamic studies revealed spontaneous adsorption, suggesting a physical character enhanced by a positive entropy variation.

Abstract Bioadsorption using agricultural waste offers a promising approach for removing toxic metals from wastewater. This study explores the potential of chemically activated banana peels (BPs) as a green and cost-effective bioadsorbent for Cu(II) and Zn(II) removal. Fourier-transform infrared (FTIR) spectroscopy revealed the presence of functional groups like alcohols, phenols, and amino acids on activated BPs, potentially responsible for metal ion binding. Scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS) confirmed the presence of cavities on the BPs surface and the existence of oxygen and potassium. The adsorption capacity of BPs was investigated under various conditions, including pH, contact time, sorbent dosage, metal concentration, and temperature. This study used Langmuir, Freundlich, Tempkin, and Dubinin–Radushkevich (D–R) isotherm models to describe the equilibrium results of Cu (II) and Zn (II) adsorption. The Langmuir isotherm model best described the adsorption process, suggesting monolayer coverage of metal ions on the BPs surface. Maximum adsorption capacities were 3.2 mg g−1 for Cu(II) and 2.8 mg g−1 for Zn(II), demonstrating the effectiveness of BPs in metal removal. Kinetic studies indicated pseudo-first-order (PFO) behavior for Cu(II) and pseudo-second-order (PSO) behavior for Zn(II) adsorption. Thermodynamic analysis revealed a spontaneous and exothermic process (negative Gibbes free energy (ΔG°) and enthalpy (ΔH°) with decreased randomness [negative entropy (ΔS°)] at the biosorption interface. Finally, the BPs sorbent was successfully applied to remove different metal ions from real wastewater samples collected from the El Wadi drain.

A novel method has been explored based on the recovery of two industrial wastes V2O5 and phosphogypsum from the fertilizer production industry, which also provide a significant challenge due to their toxicity and environmental impact. To solve the problem of these two harmful wastes, these residues have been transformed into valuable resources, by the elaboration of Nanoparticles vanadate-hydroxyapatite (NPs-HAP/VAP) adsorbent, contributing a sustainable solution without requiring expensive or highly skilled work. This comprehensive investigation explores the adsorption of the reactive red 141 dye (RR 141) on Ca10(VO4) x(PO4)6-x(OH)2, with (xi = 0, 1.5, 3, 4.5, and 6). Using a Centered composite design (CCD), several parameters influencing the adsorption process were examined. The optimal adsorption capacity is 50 mg. g - 1 under optimal conditions 57.5 mg of the adsorbent dose, 152.5 mgL-1 for the RR 141, pH 8, 92.5 minutes of contact time, and incorporation ratio of 4.5 with an R2 of 0.99. These results reinforce the effectiveness of our chosen CCD model. Kinetic analysis demonstrated a pseudoorder reaction model with an R² > 0.92, while the Sips isotherm describes the adsorption process. Thermodynamic studies revealed spontaneous adsorption, suggesting a physical character enhanced by a positive entropy variation. [ABSTRACT FROM AUTHOR]

AbstractThis study investigates the equilibrium and kinetics of copper and cadmium adsorption from aqueous solutions using groundnut husk. Characterization of the groundnut husk reveals various functional groups and a porous morphology. Isothermal studies were conducted, and different models were evaluated to fit the data. The Langmuir model exhibits the best fit for copper adsorption, while the Temkin and Dubinin–Radushkevich (DR) isotherm models show superior fitting for cadmium adsorption. Results suggest that physisorption significantly influences both cases, with mean sorption adsorption energy lower than 8000 J/mole. Error analysis reveals that the Freundlich and Temkin models demonstrate maximum adsorption capacity, with lower Chi-square (ꭓ2), Sum of Square Errors (SSE), and SAE compared to Langmuir and DR models. Additionally, intra-particle diffusion was analyzed using the Weber and Morris equation. Evaluation of model parameters indicates that cadmium demonstrates better nonlinear fitting of data compared to copper. FTIR and SEM analysis confirm the involvement of various functional groups in adsorption and reveal changes in surface distribution post-adsorption due to copper and cadmium presence. [ABSTRACT FROM AUTHOR]

Ibuprofen is widely used to reduce minor aches and fevers from a various condition such as the common flu. The increase in the waste of ibuprofen may cause contamination and raise a serious problem in the water effluence. It is needed to reduce the waste of ibuprofen by the adsorption process. Both cellulose from empty fruit bunch and modified bimetal oxides Fe3O4-Ag2O were synthesized and characterized as magnetic Fe3O4-Ag2O/cellulose adsorbent. The BET surface area was 177.7 m²/g with a predominantly mesoporous structure. SEM EDX spectra proved an unsmooth adsorbent with irregular-sized particles. FTIR spectra at 552-693 nm are assigned to Fe-O and Ag-O stretching vibration. XRD pattern analysis shows the crystallized size is 34.16 nm. The highest removal efficiency of ibuprofen was obtained at acidic conditions (pH = 2), a concentration of 200 ppm, and a contact time of 120 min. The equilibrium adsorption data proved that the Freundlich isotherm is more favorable than the Langmuir isotherm model. The kinetic model showed that the pseudo-first-order is a more suitable model than the second-pseudo-order. The result of the experimental data proved that the Fe3O4-Ag2O/cellulose will be a potential adsorbent for ibuprofen removal. [ABSTRACT FROM AUTHOR]

In this work, the efficacy of two metal–organic frameworks (MIL-101(Fe) and NH2-MIL-101(Fe)) in eliminating acetamiprid (ATP) insecticide and eosin Y (EY) dye from aqueous solution is tested. An analysis was conducted on the developed nanocomposite's optical, morphological, and structural characteristics. The adsorption isotherm, kinetics, thermodynamics, reusability, and mechanisms for ATP and EY dye removal were assessed. NH2-MIL-101(Fe) adsorbed 76% and 90% of ATP pesticide and EY dye, respectively after 10 to 15 min in optimum conditions. For both adsorbents, with regard to explaining the isotherm data, the Langmuir model offered the most accurate description. Moreover, the adsorption of ATP and EY dye is described by the pseudo-second-order kinetic model. The maximum adsorption capacities of ATP and EY dye on MIL-101(Fe) were 57.6 and 48.9 mg/g compared to 70.5 and 97.8 mg/g using NH2-MIL-101(Fe). The greatest amount of ATP and EY dye clearance was obtained at a neutral medium for both adsorbents. The results of this investigation demonstrate the effectiveness of MIL-101(Fe) and NH2-MIL-101(Fe) as effective substances in the adsorption process for removing pesticides and dyes from aqueous solution. [ABSTRACT FROM AUTHOR]

This study aimed to compare the adsorption of Pb(II) ions from an aqueous solution using non-devulcanized (NTR) and devulcanized tyre rubber (DTR) powder. Both types of rubber particles were prepared from used truck tyres, with DTR processed through mechano-chemical devulcanization. The adsorption experiments were conducted using 100–200 µm particles, with adsorbent doses ranging from 5 to 15 g/L. Effects of adsorbent dose, initial metal concentration and contact time were investigated. Characterization of both adsorbents was done using SEM–EDS, FTIR, and XRD analysis. Different adsorption isotherm and kinetic models were used to analyse the adsorption mechanisms. The results of the study showed that DTR was significantly more efficient at adsorbing Pb(II) compared to NTR. The maximum adsorption capacities estimated from the Langmuir equation were 75.1 mg/g and 6.61 mg/g for DTR and NTR, respectively. Among the kinetic models tested, pseudo 2nd order kinetic model was found to be the most suitable for tyre rubber adsorbents. The optimal dose and contact time were found to be 5 g/L and 120 min, respectively, for both adsorbents. The superior performance of DTR in Pb(II) adsorption was attributed to the change in the surface morphology of the rubber during the devulcanization process, resulting in increased surface roughness. The adsorption of Pb(II) was accompanied by the leaching of Zn from both types of rubber, suggesting that an ion exchange mechanism might be involved in the adsorption process. In conclusion, devulcanization appears to be a viable method for improving the adsorption properties of tyre rubber. [ABSTRACT FROM AUTHOR]

This study proposed a treatment strategy based on the application of poly(vinyl alcohol)-based magnetic hydrogel (PVA-MH) beads for the adsorptive removal of cadmium from synthetic domestic wastewater. The hydrogels were prepared through a facile and rapid synthesis procedure and used to remove cadmium ions from domestic wastewater. The influential parameters of adsorption process were studied by varying the type and volume of buffer solution, mass of adsorbent, and shaking period. The optimum parameters of the adsorption process were found as 1.0 mL of pH 8.0 buffer solution, 100 mg of PVA-MH beads, and 30 min orbital shaking. The process of adsorption equilibrium was clarified by the three-parameter Sips model, and outcomes indicated that this model, with an R2 value of 0.9876, fitted the experimental data effectively. Moreover, sorption kinetic results are well described by the pseudo-second-order kinetic model. The findings indicated that both monolayer adsorption and multi-site interactions governed the adsorption of cadmium onto the hydrogel surface and the swelling characteristics of PVA-MH beads had a low influence on the adsorption mechanism. [ABSTRACT FROM AUTHOR]

Fluoride contamination in groundwater may pose serious health issues. Among all the technologies, adsorption is considered to be highly efficient and is widely used for remediation in environment. In the present study, copper oxide nanoparticles (CuO) were synthesized by chemical precipitation method and used as adsorbent. The study intends to examine copper oxide nanoparticles behaviour when fluoride ions are present in an aqueous solution. The batch mode experiment demonstrated a substantial ability of the copper oxide nanoparticles for adsorption of fluoride with an adsorption capacity of 69.9 mg/g at a pH of 6, temp 298 K and adsorbent dose of 0.5 g/L. [ABSTRACT FROM AUTHOR]

This study explores the efficient removal of the synthetic anionic dye-reactive red Me4BL (RRMe4BL) from an aqueous medium which is a significant contributor to environmental pollution. The present study investigates the synthesis of zinc oxide, nickel oxide, cobalt oxide and copper oxide nano adsorbents (ZnO (II), NiO (II), CoO (II), CuO (II)) through the co-precipitation method and their effectiveness in eliminating the reactive red dye Me4BL(RRMe4BL). Maximum adsorption capacities were achieved at pH 2 for ZnO (96.1 mg/g), NiO (86.9 mg/g), CoO (93.4 mg/g) and at pH 6 for CuO (76.3 mg/g) under a 0.05 g/50 mL nano-adsorbent dose, 50 mg/L dye initial concentration and 25°C T and 90 min of contact time. The fitness of the pseudo-2nd-order model explained the kinetics, while Langmuir and Temkin adsorption isotherm highlighted the efficiency of the dye adsorption. Thermodynamic studies revealed the spontaneous and exothermic nature of adsorption. The influence of electrolytes, surfactants and desorption was also analysed. Characterisation of the nanoparticles was done through SEM, XRD and FTIR which revealed the morphology and functional groups of nano-adsorbents. The adsorption method used for eliminating this anionic red dye shows several benefits, including affordability, simplicity of use and the presence of intelligent adsorbents for environment-friendly removal of industrial dyes from wastewater. [ABSTRACT FROM AUTHOR]

In this study, a new natural polysaccharide material, i.e., n-LTP, was synthesized by mixing Linum usitatissimum seed oil cake, Trigonella foenum-graecum and Plantago physilium husk in a 1:1:1 ratio for adsorption of Methylene blue. BET, FTIR and SEM reveal the presence of various organic and inorganic groups besides heterogeneous surfaces of the adsorbent having a surface area of 384 m2/g. It is observed that at pH values of 12, contact time of 100 min, n-LTP dose of 1.5 mg, with dye concentration of 70 ppm at 50 °C, nearly 88% of adsorption take place. Experimental data shows that the Freundlich isotherm (R2 = 0.96) and pseudo-first-order kinetic model (R2 = 0.9538) fit best to the process. A thermodynamic study showed that the process was spontaneous, endothermic and feasible. Electrostatic, π -π and hydrogen bonding interactions are involved in MB dye adsorption on n-LTP as confirmed by a surface complexation model (SCM). Overall, results of the study explored the potential f n-LTP for removal of MB dye from contaminated water. This study is novel as till now, to the best of our knowledge, no work has been reported on MB adsorption using n-LTP as Q5 an adsorbent specifically. HIGHLIGHTS Water is significant for sustaining good health and regulating the body temperature.; Synthesis of new natural polysaccharide material (n-LTP) in a 1:1:1 ratio.; Characterization of n-LTP, effect of adsorption parameters, kinetics, isotherm models and thermodynamics was studied.; Synthesized n-LTP is an effective adsorbent for adsorption of MB dye via ionic interactions.;

Methyl violet 6B (MV6B), found in wastewater, poses hazardous effects to aquatic ecosystems and human health; therefore, it must be removed immediately. In response, this study pioneered the development of a dye adsorbent by incorporating phenolated alkali lignin (PAL) into magnetite (Fe3O4), offering a solution for MV6B removal. Lignin was extracted from coconut husk through alkali extraction, chemically modified using phenolation, and integrated onto the magnetite surface. SEM and FTIR spectroscopy were used to characterize the adsorbent, and various parameters were optimized, along with evaluations of the adsorption kinetics and isotherm models, as well as the adsorbent’s reusability. PAL was successfully deposited onto the magnetite based on the characterization. The experimental results revealed that the optimal conditions for the removal of MV6B using PAL/Fe3O4 composite are pH 4, a temperature of 313 K, a dosage of 0.10 g PAL/Fe3O4 per 15 mL of MV6B, and a contact time of 150 minutes. MV6B’s equilibrium removal rate was 95.1%, with an adsorption capacity at equilibrium of 6.42 mg/g. The adsorption of MV6B followed a pseudo-second-order kinetic model and the Freundlich model isotherm. A thermodynamic study showed that the adsorption process was spontaneous and exothermic. PAL/Fe3O4 was highly reusable after three cycles without the need for desorption. Hence, this study has demonstrated that the PAL/ Fe3O4 adsorbent is practical, economical, and efficient for wastewater treatment.

Abstract The public health and environment are currently facing significant risks due to the discharge of industrial wastewater, which contains harmful heavy metals and other contaminants. Therefore, there is a pressing need for sustainable and innovative technologies to treat wastewater. The main objective of this research was to develop novel composites known as chitosan, Padina pavonica, Fe(III), and nano MgO incorporated onto pomegranate peel with the specific purpose of removing Cd (II) and Cu (II) ions from aqueous solutions. The characterization of these nanocomposites involved the utilization of several analytical methods, including Fourier-transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, thermal gravimetric analysis, and X-ray photoelectron spectroscopy. The efficiency of these nanocomposites was evaluated through batch mode experiments, investigating the impact of factors such as pH, initial concentration, contact time, and adsorbent dose on the adsorption of Cu(II) ions. The optimum conditions for the removal of ions were pH = 5 for Cu (II) and 6 for Cd (II), contact time: 120 min, adsorbent dosage: 0.2 g, initial metal ion concentration: 50 mg/L for each metal ion for the present study. The MgO@Pp demonstrated the highest removal efficiencies for Cu(II) and Cd(II) at 98.2% and 96.4%, respectively. In contrast, the CS@Fe-PA achieved removal efficiencies of 97.2% for Cu(II) and 89.2% for Cd(II). The modified MgO@Pp exhibited significantly higher total adsorption capacities for Cu(II) and Cd(II) at 333.3 and 200 mg/g, respectively, compared to CS@Fe-PA, which had capacities of 250 and 142 mg/g, respectively. The adsorption of Cd (II) and Cu (II) ions by MgO@Pp was found to be a spontaneous process. The R2 values obtained using the Freundlich and Redlich-Peterson models were the highest for the MgO@Pp composite, with values of 0.99, 0.988, 0.987, and 0.994, respectively, for Cu (II) and Cd (II). The pseudo-second-order equation was determined to be the best-fit kinetic model for this process. Reusability experiments confirmed that the adsorbents can be utilized for up to four regeneration cycles. Based on the findings of this study, MgO @ Pp is the most promising alternative and could be instrumental in developing strategies to address existing environmental pollution through adsorption.

In this study, waste tires (WTs) were carbonized under an N2 atmosphere. Subsequently, KOH/WTs‐char with KOH‐assisted CO2 activation was used to prepare activated carbon (AC) as a highly porous carbon material for the removal of Cr(VI) and Cd(II) from water. Various techniques such as elemental analysis, Fourier‐transform infrared spectroscopy, scanning electron microscopy, and N2 adsorption/desorption were employed to investigate the physical and chemical characteristics of the prepared carbons. The WTs‐char activated with KOH under CO2 exhibited a microstructure with a high BET surface area and pore volume of 1841 m2/g and 0.869 cm3/g, respectively, demonstrating excellent adsorbent performance. The maximum removal efficiencies of 99.91 % for Cd(II) and 99.81 % for Cr(VI) were achieved using AC2 carbon under the following conditions: pH 2 for Cr(VI) and pH 5 for Cd(II), contact time of 120 min, adsorbent dose of 0.4 g/100 mL, and temperature of 298 K. The adsorption kinetics followed the pseudo‐second‐order equation, and the equilibrium data fit well with the Redlich–Peterson isotherm equation. The positive values of ▵G indicated that the uptake process for both ions was nonspontaneous and nonfeasible over the temperature studied. Both ions showed negative values of ΔH and ΔS on carbon, suggesting exothermic adsorption and a decrease in disorder. Regeneration studies showed that NaOH was a better desorbing agent than HCl. Cr(VI) desorption resulted in over 90 % removal recovery by AC2 using 1.0 M NaOH even after the fifth cycle. However, the low activation energy indicated that the adsorption was favorable kinetically. Overall, this study demonstrated the effective preparation of highly porous carbon and its successful performance in removing Cr(VI) and Cd(II) ions. [ABSTRACT FROM AUTHOR]

Methyl violet 6B (MV6B), found in wastewater, poses hazardous effects to aquatic ecosystems and human health; therefore, it must be removed immediately. In response, this study pioneered the development of a dye adsorbent by incorporating phenolated alkali lignin (PAL) into magnetite (Fe3O4), offering a solution for MV6B removal. Lignin was extracted from coconut husk through alkali extraction, chemically modified using phenolation, and integrated onto the magnetite surface. SEM and FTIR spectroscopy were used to characterize the adsorbent, and various parameters were optimized, along with evaluations of the adsorption kinetics and isotherm models, as well as the adsorbent’s reusability. PAL was successfully deposited onto the magnetite based on the characterization. The experimental results revealed that the optimal conditions for the removal of MV6B using PAL/Fe3O4 composite are pH 4, a temperature of 313 K, a dosage of 0.10 g PAL/Fe3O4 per 15 mL of MV6B, and a contact time of 150 minutes. MV6B’s equilibrium removal rate was 95.1%, with an adsorption capacity at equilibrium of 6.42 mg/g. The adsorption of MV6B followed a pseudo-second-order kinetic model and the Freundlich model isotherm. A thermodynamic study showed that the adsorption process was spontaneous and exothermic. PAL/Fe3O4 was highly reusable after three cycles without the need for desorption. Hence, this study has demonstrated that the PAL/ Fe3O4 adsorbent is practical, economical, and efficient for wastewater treatment. [ABSTRACT FROM AUTHOR]

Algerian Eucalyptus Leaves (AEL), a natural biodegradable adsorbent abundantly available, was used for the removal of methylene blue (MB) dye. The AEL properties for the removal of MB were investigated under different conditions by varying the AEL amount, MB concentration, pH of the solution and the reaction temperature. Scanning electron microscopy (SEM) and infrared spectroscopy (FTIR) techniques have been used to characterize AEL biosorbent. Experimental results showed that the adsorption of MB dye at the concentration of 50 mg L−1 reached to 91 % at pH 10 with a stirring speed of 200 rpm and after 180 min of reaction time. The experimental data were analyzed using the linear forms of different kinetic models (pseudo-first order kinetic model, pseudo-second order kinetic model, and intra-particle diffusion models). The results demonstrated that the adsorption kinetics of MB was consistent with the pseudo-second order model with R2 value of 0.9969. The isotherm models Langmuir, Freundlich, Dubinin, Elovich, Brunaut Emmet Teller and Temkin models were also investigated to describe the adsorption equilibrium. The results show that the AEL adsorption is in accordance with Temkin isotherm. The thermodynamic study revealed that the adsorption is spontaneous and exothermic. Therefore, as a cheap green adsorbent with high MB adsorption performance, AEL is expected to become one of the best candidate materials for future industrial wastewater treatment. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the sorption behaviour of South African coal seams with relation to the effect of temperature during CO2 sequestration. The excess adsorption isotherms of CO2 adsorption were undertaken using a high‐pressure volumetric system for four coals of different coal rank (denoted by Somkele [SK], anthracite KZN [AN], Tshikondeni [TD], and Syferfontein [SF]). The volumetric pressure step method was conducted at increments of system temperature of 35, 45, 55, and 65°C for pure CO2 adsorption at incremental pressures up to 93 bar. The results showed that high temperatures have a very significant negative effect on the amount of CO2 adsorbed on the coal samples. The high‐rank coal samples (SK and AN) demonstrated elevated CO2 adsorption capacity across all tested temperatures due to their high vitrinite content. The medium‐rank coals (TD and SF) exhibited comparatively lower CO2 adsorption capacity, attributed to the presence of adsorption hindrances such as higher ash content and volatile and mineral matter. The isosteric heat of adsorption revealed an increasing trend with coverage for all coal samples, with higher rank coals displaying greater slopes. The determined range of the isosteric heat of adsorption, spanning from 10 to 59 kJ/mol, indicated that the adsorption process is primarily of a physisorption nature. Three theoretical models (Langmuir, Freundlich, and Temkin) were evaluated and fitted to the sorption experimental data. The Temkin model exhibited superior fitting compared to the Langmuir and Freundlich isotherms. The Temkin isotherm parameters suggest that the adsorption of CO2 onto coal is a physisorption process. [ABSTRACT FROM AUTHOR]

Malachite green (MG) is a synthetic cationic dye extensively utilized in the textile industry for colouring purposes. It is a mutagenic agent and potentially carcinogenic for living organisms in nature. Therefore, it is necessary to treat and discharge the industrial effluents covering MG to avoid irreversible and serious effects on both living organisms and the environment. The photocatalyst SnO2 was synthesized by a new method by complexation of sodium diethyldithiocarbamate with tin dichloride pentahydrate, followed by calcination at 450, 600 and 750°C and utilized for photocatalytic degradation of MG dye. The better degradation was obtained at calcination temperature 600°C. The fluorescent light exposure resulted better degradation % of MG dye within 20 min, and the absorbance measurements were noted after every 5 min. The degradation of MG dye improved with an increase in the dose of SnO2 photocatalyst up to 20 mg. The highest decomposition of MG dye was found at 10 pH which may be due to deprotonation. The effects of Na+, HCO3−, Ca2+, Cl−, K+, SO42− and Mg2+ on dye degradation were examined and results showed that the salts had no effect on degradation. The kinetics and isothermic studies were carried out where the kinetic model pseudo-second-order and Langmuir isotherm were highly fitted. The factorial design was also drawn to checked the combined effects of variables, such as pH, dose, concentration and irradiation time on the degradation of MG dye. [ABSTRACT FROM AUTHOR]

Due to industrial activity, heavy metal contamination is present in water, air, and soil around the world. Due to this circumstance, serious environmental issues arise. Natural kaolin (NK) clay underwent batch processing to remove Hg2+. Scanner electron microscopy (SEM), energy dispersion spectroscopy (EDS), x‐ray diffraction (XRD), and Brunauer–Emmett–Teller (BET) were used to analyze the morphological and chemical characteristics of kaolin. Investigations were done into how adsorption is impacted by contact duration, adsorbent dosage, temperature, and solution pH. Kaolin's BET surface area was found to be 8.085 m2/g, while its pore volume was found to be 0.0537 cm3/g. The best working conditions were found to be pH 6.81 and an equilibrium period of 90 min. It was discovered that the Langmuir isotherm model was the most suitable one. At 298, 308, and 318 K, respectively, the adsorption capacities of NK were calculated to be 10.964, 10.515, and 10.101 mg/g. The pseudo‐second‐order kinetic model agreed with this. It was revealed that NK had a maximum desorption efficiency of 91.36%. Through this process, the potential of NK as an eco‐friendly adsorbent for heavy metal removal was shown. [ABSTRACT FROM AUTHOR]

Water is one of the fundamental resources for the existence of humans and the environment. Throughout time, due to urbanization, expanding population, increased agricultural production, and intense industrialization, significant pollution with persistent contaminants has been noted, placing the water quality in danger. As a consequence, different procedures and various technologies have been tested and used in order to ensure that water sources are safe for use. The adsorption process is often considered for wastewater treatment due to its straightforward design, low investment cost, availability, avoidance of additional chemicals, lack of undesirable byproducts, and demonstrated significant efficacious potential for treating and eliminating organic contaminants. To accomplish its application, the need to develop innovative materials has become an essential goal. In this context, an overview of recent advances in hydrogels based on chitosan and nanocomposites and their application for the depollution of wastewater contaminated with dyes is reported herein. The present review focuses on (i) the challenges raised by the synthesis process and characterization of the different hydrogels; (ii) the discussion of the impact of the main parameters affecting the adsorption process; (iii) the understanding of the adsorption isotherms, kinetics, and thermodynamic behavior; and (iv) the examination of the possibility of recycling and reusing the hydrogels. [ABSTRACT FROM AUTHOR]

The disposal of pharmaceutical compounds in wastewater is a significant environmental and health challenge. These drug residues can have adverse effects on aquatic ecosystems and human health. Chitosan, a natural polysaccharide derived from chitin, is promising as an effective material for adsorbing pharmaceutical waste due to its unique chemical structure containing amino and hydroxy functional groups that facilitate interactions with organic molecules in wastewater. Chitosan can adopt various structural forms, such as hydrogels, nanoparticles, beads, membranes, fibers, and aerogels, which offer opportunities to optimize its performance in adsorbing drug waste. In this review, which includes articles published in the last 5 years, the influence of chitosan's structural forms, particularly on the adsorption of pharmaceutical compounds in wastewater is explored. Furthermore, the different synthesis and fabrication methods for each chitosan form and highlight their characteristics, advantages, and specific applications, are discussed. Additionally, this review delves into the adsorption mechanisms involved in each form.

Abstract The majority of environmental researchers are becoming increasingly concerned with the manufacture of inexpensive adsorbents for the detoxification of industrial effluents. To address one of the significant and well-known pollution issues with certain drains that act as hotspots and contribute to coastal pollution in Alexandria, this study aims to develop an economical, ecologically friendly sorbent. This study assessed the efficacy of a biomass-coated magnetic composite and a magnetic active adsorbent for the removal of two dyes from an industrially contaminated sewer using a wetland plant (Phragmites australis). Using magnetic biosorbent, the biosorption of Xylenol orange and Congo red ions from polluted drain discharge in Abu Qir Bay was evaluated in the current study. Using scanning electron microscopy imaging and Fourier transform infra-red analysis; the surface function and morphology of the nano-biosorbent were examined. At room temperature, the effects of initial dye concentration, pH, contact time, and nano-biosorbent concentration have all been investigated. The greatest percentages that nano-biosorbent can remove from Congo red and Xylenol orange are 97% and 47%, respectively. The removal of the initial Congo red concentration varied from 42 to 97%, while the removal of the initial Xylenol orange concentration varied from 30 to 47%. The adsorption capacity was shown to be strongly pH-dependent; capacity dose as pH value increased, with pH 10 being the ideal pH for Congo red and pH 6 being the ideal pH value for Xylenol orange. The adsorption capacity for Congo red varied between 0.96 and 3.36 and the adsorption capacity for Xylenol orange varied between 0.18 and 17.58. The removal capacity decreased from 3.36 to 0.96 mg/g when the biosorbent dosage was increased from 0.05 to 0.5 g/L for Congo red, in case of Xylenol orange, the removal capacity increased from 0.18 to 17.58 mg/g when the biosorbent dosage was increased from 0.05 to 0.5 g/L. The removal capacity of Congo red increases quickly with time and varied from 1.66 to 1.88 of contact time; while the removal capacity of Xylenol orange varied between 3.08 and 4.62 of contact time. For the dyes under study, kinetics and adsorption equilibrium were examined. Within 180 min, the equilibrium was attained because to the quick adsorption process. For Congo red and Xylenol orange, the highest adsorption capacities were 3.36 and 17.58 mg g−1, respectively. The equilibrium data were assessed using a number of isotherm models, including Langmuir, Freundlich, BET, and Tempkin, while the kinetic data were examined using a variety of kinetic models, including pseudo-first- and pseudo-second-order equations. The pseudo-second-order equation provides the greatest accuracy for the kinetic data and Langmuir model is the closest fit for the equilibrium data.

The present work aims to evaluate the applicability of mollusk (Meretrix lusoria) shells as a biosorbent for toxic metal ions (Cd2+ and Pb2+) following the batch mode biosorption procedure. Some well-known analytical methods have been used to characterize the biosorbent such as a scanning electron microscope (SEM), an energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction. The mechanism of metal ion biosorption was examined using various analytical techniques. Therefore, an evaluation of operating factors such as contact time, pH, initial concentration of metal ions, biosorbent dose, and temperature was performed. The results obtained in this investigation indicated that the optimum conditions for the biosorption of Cd+2 and Pb+2 ions are as follows: pH = 6; contact times of 90 min; and the 20 mg/L of initial [M2+]. And a biosorbent dosage of 1.0 g/100 mL for each metal ion solution was also determined. The maximum removal efficiency results were 90.6% for Cd+2 and 91.5% for Pb+2 at pH 6.0. The biosorption isotherm was investigated using three forms of linear equilibrium (Freundlich, Langmuir, and Temkin models). Kinetic studies were also conducted to determine the equilibrium time for the biosorption of the studied metals utilizing the pseudo-second-order, pseudo-first-order, and intraparticle diffusion model. The data indicate that the biosorption kinetics of Cd2+ and Pb2+ follow the pseudo-second-order models. According to the present study, it can be identified that the shell of Meretrix lusoria is a suitable biosorbent for Cd2+ and Pb2+ ions and can contribute to their removal from environmentally polluted water.

The majority of environmental researchers are becoming increasingly concerned with the manufacture of inexpensive adsorbents for the detoxification of industrial effluents. To address one of the significant and well-known pollution issues with certain drains that act as hotspots and contribute to coastal pollution in Alexandria, this study aims to develop an economical, ecologically friendly sorbent. This study assessed the efficacy of a biomass-coated magnetic composite and a magnetic active adsorbent for the removal of two dyes from an industrially contaminated sewer using a wetland plant (Phragmites australis). Using magnetic biosorbent, the biosorption of Xylenol orange and Congo red ions from polluted drain discharge in Abu Qir Bay was evaluated in the current study. Using scanning electron microscopy imaging and Fourier transform infra-red analysis; the surface function and morphology of the nano-biosorbent were examined. At room temperature, the effects of initial dye concentration, pH, contact time, and nano-biosorbent concentration have all been investigated. The greatest percentages that nano-biosorbent can remove from Congo red and Xylenol orange are 97% and 47%, respectively. The removal of the initial Congo red concentration varied from 42 to 97%, while the removal of the initial Xylenol orange concentration varied from 30 to 47%. The adsorption capacity was shown to be strongly pH-dependent; capacity dose as pH value increased, with pH 10 being the ideal pH for Congo red and pH 6 being the ideal pH value for Xylenol orange. The adsorption capacity for Congo red varied between 0.96 and 3.36 and the adsorption capacity for Xylenol orange varied between 0.18 and 17.58. The removal capacity decreased from 3.36 to 0.96 mg/g when the biosorbent dosage was increased from 0.05 to 0.5 g/L for Congo red, in case of Xylenol orange, the removal capacity increased from 0.18 to 17.58 mg/g when the biosorbent dosage was increased from 0.05 to 0.5 g/L. The removal capacity of Congo red increases quickly with time and varied from 1.66 to 1.88 of contact time; while the removal capacity of Xylenol orange varied between 3.08 and 4.62 of contact time. For the dyes under study, kinetics and adsorption equilibrium were examined. Within 180 min, the equilibrium was attained because to the quick adsorption process. For Congo red and Xylenol orange, the highest adsorption capacities were 3.36 and 17.58 mg g−1, respectively. The equilibrium data were assessed using a number of isotherm models, including Langmuir, Freundlich, BET, and Tempkin, while the kinetic data were examined using a variety of kinetic models, including pseudo-first- and pseudo-second-order equations. The pseudo-second-order equation provides the greatest accuracy for the kinetic data and Langmuir model is the closest fit for the equilibrium data. [ABSTRACT FROM AUTHOR]

Radioactive iodine isotopes especially 131I are used for diagnosis and treatment of different types of cancer diseases. Due to the leak of radioactive iodine into the patient's urine in turn, the wastewater would be contaminated, so it is worth preparing a novel adsorption green material to remove the radioactive iodine from wastewater efficiently. The removal of 127I and 131I contaminants from aqueous solution is a problem of interest. Therefore, this work presents a new study for removing the stable iodine 127I− and radioactive iodine 131I from aqueous solutions by using the novel nano adsorbent (Nano ZnO/MWCNTs) which is synthesized by the arc discharge method. It is an economic method for treating contaminated water from undesired dissolved iodine isotopes. The optimal conditions for maximum removal are (5 mg/100 ml) as optimum dose with shacking (200 rpm) for contact time of (60 min), at (25 °C) in an acidic medium of (pH = 5). After the adsorption process, the solution is filtrated and the residual iodide (127I−) is measured at a maximum UV wavelength absorbance of 225 nm. The maximum adsorption capacity is (15.25 mg/g); therefore the prepared nano adsorbent (Nano ZnO/MWCNTs) is suitable for treating polluted water from low iodide concentrations. The adsorption mechanism of 127I− on to the surface of (Nano ZnO/MWCNTs) is multilayer physical adsorption according to Freundlich isotherm model and obeys the Pseudo-first order kinetic model. According to Temkin isotherm model the adsorption is exothermic. The removal efficiency of Nano ZnO/MWCNTs for stable iodine (127I−) from aqueous solutions has reached 97.23%, 89.75%, and 64.78% in case of initial concentrations; 0.1843 ppm, 0.5014 ppm and 1.0331 ppm, respectively. For the prepared radio iodine (131I−) solution of radioactivity (20 µCi), the dose of nano adsorbent was (10 mg/100 ml) and the contact time was (60 min) at (pH = 5) with shacking (200 rpm) at (25 °C). The filtration process was done by using a syringe filter of a pore size (450 nm) after 2 days to equilibrate. The removal efficiency reached (34.16%) after the first cycle of treatment and the percentage of residual radio iodine was (65.86%). The removal efficiency reached (94.76%) after five cycles of treatment and the percentage of residual radio iodine was (5.24%). This last percentage was less than (42.15%) which produces due to the natural decay during 10 days. [ABSTRACT FROM AUTHOR]

In this study, a highly effective hybrid adsorbent composite based on low-cost fuller's earth (FE), aluminum silicate (AS) and chitosan (CS) was prepared using a facile method. The prepared composite was applied to adsorb lead (Pb2+) and copper (Cu2+) ions from aqueous solutions. Several analyses such as Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to characterize the composite. The adsorption efficiency of the prepared composite was investigated at different operating conditions. Moreover, the adsorption isotherm/kinetic models and adsorption thermodynamics of the composite were examined. The results showed that the pseudo-second-order kinetic model described well with the obtained data and the adsorption equilibrium can be better described by Langmuir isotherm model with maximum adsorption capacities of 305.5 and 284.2 mg/g for Pb2+ and Cu2+, respectively. The obtained data demonstrated that the prepared composite is an efficient and kinetically fast metal ion removal with high adsorption capacity and recovery efficiency. [ABSTRACT FROM AUTHOR]

N-Nitrosodiphenylamine (NDPhA) is one of the most toxic water-soluble nitrosamines. Human exposure to NDPhA can induce several health effects upon exposure to, even a low dose for a long period. The removal of NDPhA from aqueous samples using an available and inexpensive adsorbent is a challenge. In this work, homemade activated carbon from a jute stick biomass was applied for almost 100% removal of NDPhA from aqueous samples. The effect of solution pH, contact time, adsorbent dosage, and adsorbate concentration have been studied and optimized. The maximum adsorption capacity was of 219.4 mg/g. The adsorption isotherm experimental results fit the Langmuir model, and the adsorption mechanisms' process follows the pseudo-second order kinetics. Furthermore, the thermodynamic parameters were calculated, and it has been found that the adsorption of NDPhA on the prepared adsorbent is thermodynamically favorable, spontaneous, endothermic, and dominated by physisorption interaction. The prepared adsorbent shows excellent affinity to the NDPhA molecules. The prepared adsorbent has a superior capability to remove around 97% of NDPhA molecules in a short period of time (45 min) from synthetic wastewater contaminated by NDPhA. Moreover, the prepared adsorbent was easily regenerated and reused for at least four times in wastewater to remove the highly toxic and carcinogenic NDPhA compound. [ABSTRACT FROM AUTHOR]

High-sugar dehydrated foods have strong hygroscopicity, which can be avoided by using drying aids. One way to assess the hygroscopic behavior is through sorption isotherms. The objective of this work was to evaluate the influence of maltodextrin concentration on sorption isotherms of powdered cajá-manga pulp in spray-dryer, lyophilization and fluidized bed spray drying processes. The dryings were carried out in a spray-dryer, lyophilizer and fluidized bed, with 10%, 20% and 30% of maltodextrin. Adsorption isotherms were determined by the static gravimetric method using salt solutions for a relative humidity range of 21% to 90%. The GAB, BET, Henderson, and Oswin models were adequate to the experimental data. The relative deviation between the experimental values and the estimated values was calculated for each curve, in order to assess which equation best fit the experimental data. The mean relative error value of less than 10% was considered one of the criteria for selecting the models. The BET (A), BET (B) and GAB (C) models had the lowest error means, 3.35%, 3.35% and 5.28%, for cajá-manga powders obtained by spray-dryer, lyophilization and fluidized bed spray drying processes, respectively, and coefficients of determination above 0.99. It is concluded that the type of drying process did not influence the behavior of the adsorption isotherms, and that increases in maltodextrin concentration and temperature are significant in reducing equilibrium moisture contents. [ABSTRACT FROM AUTHOR]

Apeanut shell was used as a low-cost agricultural waste to eliminateacid blue 25 dye from an aqueous solution. Contact time, sorbate concentration, particle size, and sorbent mass were all investigated in batch sorption tests. The sorption process was investigated in terms of equilibrium and kinetics models. The sorption process is better in agreement with the pseudo-second-order model, with a greater regression coefficient value of 1 under all experimental conditions, according to adsorption kinetic results. The models of Freundlich, Langmuir and Temkin were used to describe the isotherms of adsorption, and equilibrium data was consistent with Freundlich isotherm with a higher regression coefficient value, R2 . Based on the findings, the peanut shell is much more economical, cheap, viable, and very effective for the removal of acid blue 25 dye from aqueous solution. [ABSTRACT FROM AUTHOR]

This article presents a complex set of research activities related to the sorption analysis of the process of dyeing acrylic fibers with cationic dyes to clarify the complex events during the adsorption of dye molecules for fibers and their diffusion into the interior. Typical acrylic fibers were used for dyeing with cationic blue dye. The fiber samples were dyed in a constant bath, the initial dye concentration and dyeing time were varied. The results reveal that the degree of dye exhaustion on acrylic increases as the initial concentration of dye increases. A longer time carries a higher degree of exhaustion, the same happens with the amount of adsorbed dye per unit mass of the acrylic. Isothermal linear modeling of the dyeing process gives results according to which the Langmuir model best covers the experimental points, thus confirming the existence of monolayer dye adsorption, with a uniform distribution of adsorption heat and affinity over the homogeneous fiber surface. The Freundlich and Hill–de Boer isotherm models give somewhat weaker results for the interpretation of equilibrium acrylic dyeing. [ABSTRACT FROM AUTHOR]

Batch experiments were conducted to test orange waste (OW), an agricultural solid waste byproduct from the orange juice manufacturing industry, as adsorbent for binary solutions of Cd2+-Cr3+ and Zn2+-Cr3+. Fourier transform infrared spectroscopy (FTIR) and the point of zero charge (pHpzc) were used to identify the functional groups on the OW surface involved in biosorption. The biosorption equilibrium data for both binary-metal solutions were obtained and fitted to various isotherm models. The extended Sips and the non-modified Redlich-Peterson isotherm models gave the best fit for the experimental data. According to the extended Sips model, the maximum biosorption capacity of OW was 0.573 mmol·g−1 for Cd2+, 0.453 mmol·g−1 for Zn2+, and 1.96 mmol·g−1 for Cr3+. The sorption capacity dropped to 0.061 mmol·g−1 for Cd2+ and to 0.101 mmol·g1 for Zn2+ in their binary systems with Cr3+ for the higher initial metal concentrations in the solution. However, the maximum sorption capacity of chromium was only slightly affected by the presence of Cd2+ or Zn2+. For both binary systems, the presence of a second metal ion in the solution always conduces to a reduction in the sorption of the other metal in the solution. The presence of Cr3+ decreased the sorption of Cd2+ and Zn2+ more than vice versa. Conclusively, effective removal of Cr3+ ions from an aqueous solution can still be achieved in the presence of Cd2+ or Zn2+. [ABSTRACT FROM AUTHOR]

This study presents two environmental aspects: valorisation of natural oil shale (NOS), on the one hand, and, on the other hand, to study the effectiveness of adsorption of methylene blue (MB) dye onto material (NOS). In this context, the most characterisations of adsorbent before and after adsorption process were investigated by several methods such as x-ray diffraction (XRD), scanning electronic microscopy (SEM) and Fourier transforms infrared spectrometry (FTIR), according to these results, the NOS is rich in quartz and calcite, the matrix clay contains the kaolin and illite and present a layer structure. The total number of results showed that the adsorption of MB onto NOS is best by pseudo-second-order fitting model with a good correlation (R2 = 0.98), on the other hand the adsorption process was described well by Langmuir isotherm with a maximal capacity of adsorption equal 29 mg/g. The effect of temperature on the adsorption of the dye was also evaluated and the thermodynamic parameters were determined. The negative values of the three thermodynamic parameters ΔH °, ΔG ° and ΔS ° of the NOS/MB system indicate that the adsorption is spontaneous, exothermic and the activated energy indicates that the adsorption mechanism might be a physical sorption process. [ABSTRACT FROM AUTHOR]

Recently, considerable attention has been given to using magnetic nanoparticles (MNPs) for capturing oil from oil-in-water (O/W) emulsions, despite MNPs' inherent instability and agglomeration. Their stabilization through changing surface chemistry is required to increase dispersivity. In this research, we use cetyltrimethylammonium bromide (CTAB) as a cationic surfactant to increase the positive surface charge of the particles, resulting in a better stability in the aqueous solution because of increased repulsive forces. The functionalized MNPs are characterized using transmission electron microscopy (TEM), zeta potential, and contact angle (CA) measurements. The aim of this study is to investigate the oil separation efficiency (SE) and equilibrium oil adsorption capacity of the synthesized particles, which are determined using gas chromatography analysis. We also study the adsorption behavior using isotherm and kinetic models. The SE values indicate the superior performance of MNP@CTAB for oil adsorption from dodecane-in-water nanoemulsion (SE = 99.80%) compared to the bare MNPs with SE of approximately 57.46%. These findings are attributed to the stronger electrostatic attraction between the MNP@CTAB having high positive charge and negatively charged oil droplets. The adsorption isotherm results using both linear and non-linear regression methods show that the Freundlich isotherm is the best fit to the experimental equilibrium data (with calculated R2 > 0.97), verifying a multilayer heterogeneous adsorption. Moreover, the pseudo-first-order kinetic model describes the experimental equilibrium data in a greater congruence (R2 = 0.99), suggesting physical adsorption of oil onto MNPs through van der Waals and physical bonding, which is also confirmed through zeta potential measurements. [ABSTRACT FROM AUTHOR]

For this research, the utilisation of electrocoagulation (EC) toremove theciprofloxacin (CIP) and levofloxacin (LVX) from aqueous solutions was examined. The effective removal efficiencies are 93.47% for CIP and 88.00% for LVX, under optimum conditions. The adsorption isotherm models with suitable mechanisms were applied to determine the elimination of CIP and LVX utilizingtheEC method. Thefindingsshowed the adsorption of CIP and LVX on iron hydroxide flocs followed the Sips isotherm, with correlation coefficient values (R2) of 0.939 and 0.937. Threekinetic models were reviewed to determine the accurate CIP and LVX elimination methods using the EC method. The results showed that itfittedfor the second-order model, which indicated that the chemical adsorption mechanism controlled the removal of CIP and LVX. The R2 with CIP is 0.944, and LVX is 0.941. For binary system removal, efficiencies were 93.00, 90.10, and 96.30% for CIP, and 91.80, 96.10, and 92.97% for LVX, at the CIP ratio: LVX of 1:1, 1:4, and 4:1. The electrode consumption (ELC) and electrical energy consumption (EEC) were found at 0.208 g and 3.21 kWh−3 for a single operation. The operating cost was estimated at 0.613 US$ m−3. [ABSTRACT FROM AUTHOR]

This research involves evaluating the use of modified orange peel (MOP) in the removal of Pb2+ and Hg2+ from wastewater. For the modification process, certain concentrations of ethanol, NaOH, and CaCl2 solution were added to the washed and dried orange peel and kept at room temperature for 24 hours. The mixture was then subjected to filtration and rinsed with distilled water until the pH level reached 7. For this reason, the effects of Pb2+ and Hg2+ on the adsorption efficiency were examined by performing batch experiments. The surface properties of MOP were investigated using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and Fourier transform infrared spectroscopy (FT‐IR) techniques. The results revealed that, among the various models, the Langmuir isotherm model provided the best fit to the isotherm data for Hg2+ and Pb2+ ions. Based on the kinetic data of adsorption, the pseudo‐second‐order kinetic model provided a more accurate description of the adsorption process for Pb2+ and Hg2+ ions. According to thermodynamic analyses, both metal ions bind to MOP spontaneously and endothermally. MOP was determined to be a reliable and valid alternative material for the removal of Pb2+ and Hg2+ from aqueous environments based on its qualities such as high adsorption capacity, ease of availability, low cost, use of agricultural waste, recycling potential, and no environmental impact. [ABSTRACT FROM AUTHOR]

Toluene and xylene are carcinogenic and toxic compounds, and their presence in excessive amounts in the environment has an adverse impact on water quality, thus affecting public health. In this study, magnetite coated oleic acid, (MNP-OA) nanocomposite was synthesized, characterized and applied as an effective nano-adsorbent for the efficient removal of toluene and xylene from aqueous solutions. Magnetite nanoparticles were coated with oleic acid via the microwave method and characterized using BET surface area, XPS, SEM-EDX and pHpzc analysis. Batch adsorption studies were performed to optimize operating parameters including solution pH, adsorbent dose, contact time, and initial concentration. The impact of hydrophobic coating on the kinetics, equilibrium, and the mechanism of toluene and xylene uptake were determined. Characterization confirmed the surface coating of magnetite with oleic acid which evidenced from the additional oxygenated functional groups such as hydroxyl and carboxylic groups. The morphological analysis showed spherically shaped magnetite nanoparticles. Maximum adsorption capacity of 133.57 mg/g for toluene and 161.01 mg/g for xylene were attained at solution pH of 8, adsorbent dose of 0.1 g and concentration of 100 mg/dm3 at 298 K. The pseudo-second-order and Langmuir models best explained the kinetics and adsorption isotherm, respectively. The thermodynamic parameters, including Gibbs free energy, enthalpy change, and entropy change of adsorption indicated that the adsorption process was endothermic and spontaneous in nature. The MNP-OA nanocomposites can be applied as a reusable, cost-effective, and efficient adsorbent for toluene and xylene remediation and could be considered for other volatile organic compounds in future application. [ABSTRACT FROM AUTHOR]

Current research explains the comparison of linear and nonlinear regression methods for finding the optimal isotherm study using experimental data for the adsorption of BG on multiwalled carbon nanotubes MWCNTs. BG dye maximum adsorption onto MWCNTs occurred at pH 2 and 35°C, with the apparent equilibrium reached after 15 min. In this study, five error functions were used: ERRS, Hybrid, Chi-square (χ2 ), ARE, and EABS. The values of error functions suggest that the Langmuir Linear type 3 is a suitable isotherm to describe the adsorption of BG on MWCNTs. The results showed that the Langmuir isotherm is a fit good isotherm to describe the adsorption process. The coefficient of non-determination (K2 ) showed Hybrid, and ERRS were the preferable error functions used to predict the fit of linear and nonlinear isotherm models. Compared with other studies, MWCNTs can be used as a low-cost adsorbent with low contact time for the removal of BG dye from an aqueous solution. [ABSTRACT FROM AUTHOR]

The present work investigated the utilization of dead biomass of the highly multi-heavy metals tolerant indigenous fungal strain NRCA8 isolated from the mycobiome of fertilizer industry effluents that containing multiple heavy metal ions at high levels to remove Pb2+, Ni2+, Zn2+, and Mn2+ as multiple solutes from multi-metals aqueous solutions for the first time. Based on morphotype, lipotype and genotype characteristics, NRCA8 was identified as Cladosporium sp. NRCA8. The optimal conditions for the bioremoval procedure in the batch system were pH 5.5 for maximum removal (91.30%, 43.25%, and 41.50%) of Pb2+, Zn2+ and Mn2+ but pH 6.0 supported the maximum bioremoval and uptake of Ni2+ (51.60% and 2.42 mg/g) by NRCA8 dead biomass from the multi-metals aqueous solution, respectively. The 30 min run time supported the highest removal efficiency and uptake capacity of all heavy metals under study. Moreover, the equilibrium between the sorbent NRCA8 fungal biomass and sorbates Ni2+, Pb2+ and Zn2+ was attained after increasing the dead biomass dose to 5.0 g/L. Dead NRCA8 biomass was described by scanning electron microscopy, energy-dispersive X-ray spectroscopy and Fourier transform infrared spectrometer before and after biosorption of Pb2+, Ni2+, Zn2+ and Mn2+ under multiple metals system. The Langmuir, Freundlich and Dubinin-Kaganer-Radushkevich isotherms were applied to characterize the adsorption equilibrium between Pb2+, Ni2+, Mn2+ and Zn2+ and the adsorbent NRCA8. By comparing the obtained coefficient of regression (R2) by Freundlich (0.997, 0.723, 0.999, and 0.917), Langmiur (0.974, 0.999, 0.974, and 0.911) and Dubinin-Radushkevich (0.9995, 0.756, 0.9996 and 0.900) isotherms values for Pb2+, Zn2+, Ni2+ and Mn2+ adsorption, respectively, it was found that the isotherms are proper in their own merits in characterization the possible of NRCA8 for removal of Pb2+, Zn2+, Ni2+ and Mn2+. DKR isotherm is the best for Pb2+ and Ni2+ (0.9995 and 0.9996) while Langmiur isotherm giving a good fit to the Zn2+ sorption (0.9990) as well as Freundlich isotherm giving a good fit to the Mn2+ sorption (0.9170). The efficiencies of Cladosporium sp. NRCA8 dead biomass for bioremoval of heavy metals from real wastewater under the optimized conditions were Pb2+, Ag+, Mn2+, Zn2+ and Al3+ ˃ Ni2+ ˃ Cr6+ ˃ Co2+ ˃ Fe3+ ˃ Cu2+ ˃ Cd2+. Dead NRCA8 biomass showed efficient ability to adsorb and reduce harmful components in the industrial effluents to a level acceptable for discharge into the environment. [ABSTRACT FROM AUTHOR]

Environmental pollution from chemicals utilized in manufacturing, pharmaceuticals, and chemical process industries is of serious concern nowadays due to the contamination that ensues when these chemicals are discharged into water bodies. Activated carbon adsorption provides an efficient and economically viable means for mitigation of toxic chemicals (i.e., heavy metals, dyes, pharmaceutics, and antibiotics). However, the exorbitant cost of commercial activated carbons has resulted in the search for low-cost alternatives for the treatment of contaminated effluents. An exhaustive literature survey in this area is necessary to know the extent of work done in this area and seek out the gaps that future research will provide answers to. In this review, various works on activated carbon utilization, batch adsorption, fixed-bed adsorption (experimental and numerical studies) are summarized. This review elucidates the different kinetic and isotherm models of agrowastes-derived activated carbon materials in context with pollutants (dyes, heavy metals, pharmaceuticals, miscellaneous adsorbates) removal through batch and column methods. In addition, fixed-bed column adsorption/regeneration methods using various activated carbons derived from agrowastes are discussed. Among these methods, heavy metal adsorption from aqueous solutions by the activated carbons is the most efficient. The deployment of mathematical and machine learning approaches (ANN and novel GMDH algorithms) in optimization of batch and continuous adsorption processes are also highlighted. Numerical simulation of fixed-column adsorption systems for more improved industrial-scale column designs is described. Conclusions and future challenges of chemicals removal from polluted wastewater utilizing agrowaste-derived activated carbons are also presented.

ABSTRACT High-sugar dehydrated foods have strong hygroscopicity, which can be avoided by using drying aids. One way to assess the hygroscopic behavior is through sorption isotherms. The objective of this work was to evaluate the influence of maltodextrin concentration on sorption isotherms of powdered cajá-manga pulp in spray-dryer, lyophilization and fluidized bed spray drying processes. The dryings were carried out in a spray-dryer, lyophilizer and fluidized bed, with 10%, 20% and 30% of maltodextrin. Adsorption isotherms were determined by the static gravimetric method using salt solutions for a relative humidity range of 21% to 90%. The GAB, BET, Henderson, and Oswin models were adequate to the experimental data. The relative deviation between the experimental values and the estimated values was calculated for each curve, in order to assess which equation best fit the experimental data. The mean relative error value of less than 10% was considered one of the criteria for selecting the models. The BET (A), BET (B) and GAB (C) models had the lowest error means, 3.35%, 3.35% and 5.28%, for cajá-manga powders obtained by spray-dryer, lyophilization and fluidized bed spray drying processes, respectively, and coefficients of determination above 0.99. It is concluded that the type of drying process did not influence the behavior of the adsorption isotherms, and that increases in maltodextrin concentration and temperature are significant in reducing equilibrium moisture contents.