Equilibrium Kinetic Models Research Articles

Development of Biomass Derived Adsorbents using Wood Apple Pulp for the Removal of Contaminants

This study involves the development of biomass derived adsorbents from wood apple pulp for water and wastewater treatment. This biomass was modified by the addition of commercially available activated charcoal and copper nanoparticles. Adsorbent characterization was performed for understanding the surface morphology and surface area. These new adsorbents were further evaluated for their potentiality in removing dyes and API pollutants (Active Pharmaceutical Ingredient). All the adsorbents were highly effective in the removal of these contaminants, 96% of Malachite Green and 72% of Congo Red was removed with a high adsorption capacity of 45 mg/g. API pollutant (Ciprofloxacin) removal showed 52% removal, which is greater when compared to several modified adsorbents. Adsorption equilibrium models (Langmuir and Freundlich) and kinetic models (pseudo first order and pseudo second order) were evaluated for fit of the experimental data. In general, the isotherm studies indicated multilayer adsorption.

MnFe2O4-NH2-HKUST-1, MOF magnetic composite, as a novel sorbent for efficient dye removal: fabrication, characterization and isotherm studies

Dye in industrial wastewater is one of the most serious environmental concerns due to its potentially harmful effects on human health. Many industrial dyes are carcinogenic, toxic and teratogenic. Removal and recovery of hazardous dyes from the effluents requires efficient adsorbents. In this study, magnetic adsorbent MnFe2O4-NH2-HKUST-1 was synthesized to remove methylene blue and crystal violet dyes from aqueous solutions. The synthesized adsorbent was characterized using FTIR, XRD, BET, VSM, SEM, TGA and Zeta potential techniques. The effect of different parameters such as pH, contact time, and adsorbent dosage on the removal of dyes was investigated. The dye adsorption process was investigated by UV–Vis spectrophotometry. The maximum adsorbent capacity was obtained as 149.25 mg/g for methylene blue and 135.13 mg/g for crystal violet. The adsorption equilibrium isotherm and kinetic models were plotted and results showed that the adsorption process for both dyes is a collection of physical and chemical adsorption based on langmuir and freundlich isotherm models, and follows the pseudo-second-order adsorption kinetics. This study shows that magnetic adsorbent MnFe2O4-NH2-HKUST-1 has a good potential for removal of methylene blue and crystal violet dyes from water in a short time (5 min) and it is easily separated from the solution by a magnetic field due to its magnetic property.

Effective removal of fluoride and arsenic from groundwater via integrated biosorption and membrane ultrafiltration

Fluoride (F−) and arsenic, present as As(III) and As(V), are widespread toxins in groundwater across India, as well as in other countries or regions like Pakistan, China, Kenya, Africa, Thailand, and Latin America. Their presence in water resources poses significant environmental and health risks, including fluorosis and arsenicosis. To address this issue, this study developed an integrated process combining biosorbents and ultrafiltration (UF) for the removal of F−, As, and turbidity from contaminated water. Laboratory-scale adsorption experiments were conducted using low-cost biosorbents with different biosorbent dosages, specifically Moringa oleifera seed powder (MSP) and sorghum bicolor husk (SBH), along with sand as a binding medium. F− and As concentrations ranging from 2 to 10 mg/L and 3 to 12 mg/L, respectively, were investigated. Biosorbents and their different combinations were tested to determine their efficacy in removing dissolved F− and As. The results showed that a blend of 10-g/L MSP with SBH achieved the highest F− (97.20%) and As (78.63%) removal efficiencies. Subsequent treatment with a UF membrane effectively reduced turbidity and colloidal impurities in the treated water, achieving a maximum turbidity removal efficiency of 95.40%. Equilibrium kinetic and isotherm models were employed to analyze the experimental data, demonstrating good fit. Preliminary cost analysis indicated that the hybrid technology is economically viable and suitable for the separation of hazardous contaminants from aqueous solutions. This study underscores the potential of inexpensive biosorption technologies in providing clean and safe drinking water, particularly in industrial, rural, and urban areas.

Modelling and Optimization of Methylene Blue Adsorption Process on Leonurus cardiaca L. Biomass Powder

The main objective of this study was to optimize the adsorption process of methylene blue on a natural, low-cost adsorbent, Leonurus cardiaca L. biomass powder, in order to maximize dye removal efficiency from aqueous solutions. For this purpose, the Taguchi method was used based on an L27 orthogonal array design considering six controllable factors at three levels. The percentage contribution of each factor was computed using analysis of variance (ANOVA). The optimal adsorption conditions were established. The experimental data from equilibrium and kinetic studies were modelled using specific equilibrium isotherms and kinetic models. Thermodynamic parameters were calculated in order to determine the main adsorption mechanism. The obtained results showed that the ionic strength is the factor that most influences dye adsorption (percentage contribution 72.33%), whereas the adsorbent dose had the least impact. The Sips isotherm and the general kinetic model most accurately characterized the process. The maximum adsorption capacity 103.21 (mg g−1) indicated by the Sips isotherm and the equilibrium time (40 min) were better compared to the values obtained for other bio-adsorbents used for methylene blue adsorption. The main mechanism involved in the adsorption is physisorption, while chemisorption only contributes marginally to the process.

Adsorption of Carbon Dioxide and Methane on Cobalt Gallate-Based Metal-Organic Framework (Co-Gallate): Equilibrium Isotherm, Thermodynamic and Kinetic Studies

Biogas is mainly consisted of methane and carbon dioxide in the presence of other contaminants. The biogas purification by adsorption using metal-organic frameworks is getting attention due to the low-cost operation and high-efficiency process. Co-gallate was predicted to give a promising performance in CO2 and CH4 adsorption. However, the behaviours of CO2 and CH4 adsorption on Co-gallate are not well-explained. Therefore, this work is to synthesize Co-gallate and its performance was discussed in terms of adsorbed amount of CO2 and CH4. The experimental CO2 and CH4 pure adsorption isotherms were then fitted with equilibrium isotherm and kinetic models to describe the adsorption behaviours. Co-gallate offered a greater CO2 adsorption capacity than CH4 due to a stronger adsorbent-adsorbate interaction. The experimental pure adsorption isotherms were best fitted with Toth model compared to Langmuir, Freundlich and Sips models according to the values. Toth model described the CO2 adsorption was multilayer and heterogeneous. Thermodynamic property suggested the CO2 and CH4 adsorption were classified as exothermic process and physisorption. For kinetic models, pseudo-first order model brought the highest goodness-of-fit in terms of rate of adsorption compared to pseudo-second order and Elovich models. Pseudo-first order model reflects the adsorption rate is proportional to the number of vacant sites. It confirmed CO2 adsorption was more favourable than CH4, at lower temperature condition. In this work, the equilibrium isotherm and kinetic models were employed to select the best-fitted model in explaining the adsorption behaviours. Therefore, these behaviours of CO2 and CH4 adsorption on Co-gallate are useful in designing the future practical operation of CO2/CH4 gas adsorption.

Synthesized carboxymethyl-chitosan variant composites for cyclic adsorption-desorption based removal of Fe, Pb, and Cu

The global issue of environmental contamination from industrial wastewater comprising Cu, Fe and Pb demands effective treatment strategies. In this article, a functional composite sorbent was devised to selectively remove copper, iron, and lead from a real-world mimicking wastewater system. For the purpose, high, medium, and low molecular weight chitosan with amine and hydroxyl functional groups were used as a substrate, and glutaraldehyde was used to anchor the organic compound with carboxymethyl groups. Characterization with X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray analyzer accompanied by field emission scanning electron microscope, and Brunauer-Emmett-Teller were conducted for the synthesized adsorbent. Accordingly, the properties of the adsorbent were evaluated to infer that the synthesis assured a purified and functionalized system. The surface area of the medium carboxymethyl chitosan derivative was analyzed as 31.43 m2 g−1. Various adsorption parameters were examined methodically to assess upon optimal removal requirements. The effect of adsorbent dosage, contact time and concentration on the adsorption of the studied metal ions were conducted and the optimum values were achieved at pH 3.82, 540 min contact duration and 1.2 g L−1 sorbent dose. Maximum adsorbent capacities of 344.83 mg g−1, 9.59 mg g−1, and 90.09 mg g−1 were realized for Cu, Pb, and Fe, respectively. The experimental measurements of the studied heavy metal ions inferred the best fitness of Langmuir isotherm equilibrium and pseudo second order kinetic models. Further, elution studies with easy-to-deploy low-cost acidic and basic eluents (HCl, HNO3, H2SO4, KOH, and NaOH) were conducted with cyclic adsorption-desorption strategies. These investigations confirmed the adsorbent's good reusability up to 3 cycles of adsorption and its proximity to serve as a potential material for multi-heavy metal ions elimination from complex adsorbate systems.

Bio-sorption of Methyl blue from Synthetic wastewater onto copper\zinc oxides Bimetallic Nanoparticles Synthesized by Fusarium oxysporum: Equilibrium isotherms, Kinetic models, Process optimization, and Antibacterial activity

Bio-sorption of Methyl blue from Synthetic wastewater onto copper\zinc oxides Bimetallic Nanoparticles Synthesized by Fusarium oxysporum: Equilibrium isotherms, Kinetic models, Process optimization, and Antibacterial activity

Mô hình hấp phụ đẳng nhiệt và động học hấp phụ phosphat trên vật liệu hydrotalcit Mg-Al/CO3

In this paper, the hydrotalcite Mg-Al/CO3 material was synthesized successfully with an Mg/Al molar ratio of 2:1 by the co-precipitation method. SEM images, XRD patterns and FTIR Spectra and Energy Dispersive X-ray Spectra (EDX) of the material were analyzed. Equilibrium adsorption isotherms and kinetic models of the phosphate adsorption process on the hydrotalcite material Mg-Al/CO3 were investigated. The experimental data were analyzed by Langmuir and Freundlich models of adsorption. The phosphate adsorption on the material was well fitted to both Langmuir and Freundlich isotherms, and the maximum adsorption capacity was found to be 46.95 mg/g with the material sample was calcined at 600oC. The kinetic data obtained at different concentrations have been analyzed using a pseudo-first-order and a pseudo-second-order equation. The experimental data fitted very well with the pseudo-second-order kinetic model.

Sorption of Mercury in Batch and Fixed-Bed Column System on Hydrochar Obtained from Apple Pomace

This paper presents the methodology for the preparation of hydrochar obtained from waste materials of natural origin and investigates its applicability for removing mercury ions from aqueous systems. The sorption properties of the obtained hydrochar were investigated in a batch and in a flow-through column system. The hydrochar material was obtained from apple pomace, which was hydrothermally carbonized in 230 °C for 5 h in a hydrothermal reactor. The hydrochar formed in the process was thermally activated with an inert gas flow—CO2. Obtained materials were characterised with XRD, FTIR-ATR, SEM-EDS and nitrogen sorption (BET) analyses, which confirmed the obtaining of a highly porous carbon material with a specific surface area of 145.72 m2/g and an average pore diameter of 1.93 nm. The obtained hydrochar was analysed for sorption of mercury ions from aqueous solutions. Equilibrium isotherms (Langmuir, Freundlich, Dubinin–Radushkevich, Temkin, Hill, Redlich-Peterson, Sips and Toth) and kinetic models (pseudo-first order, pseudo-second order, Elovich and intraparticle diffusion) were determined. The sorption process of mercury on the obtained material is best described using the Freundlich isotherm and a pseudo-second-order kinetic model. This indicates that the process is chemical in nature The sorption of mercury ions from an aqueous solution with a concentration of C0 = 100 mg Hg/dm3 has been also carried out in a flow-through column system. The data obtained from adsorption were fitted to mathematical dynamic models (Bohart–Adams, Thomas, Yoon–Nelson, Clark, BDST and Yan) to illustrate the bed breakthrough curves and to determine the characteristic column parameters. The Yan model has the best fit across the study area, although the Thomas model better predicts the maximum capacity of the bed, which is qmax = 111.5 mg/g.

Equilibrium kinetics and thermodynamic studies on biosorption of heavy metals by metal-resistant strains of Trichoderma isolated from tannery solid waste.

This study was aimed at finding the metal sorption potential of six indigenous Trichoderma strains by using batch experiments for Cd (II), Cr (VI), Cu (II), and Pb (II). Trichoderma atrobrunneum showed maximum metal biosorption potential at 800mgL-1 of initial concentration. Two adsorption isotherm models, (1) Langmuir (2) Freundlich models, were employed on the biosorption data obtained at various initial metal concentrations (10mgL-1-200mgL-1) and pseudo-first (PSI) and pseudo-second (PSII) order equilibrium kinetic models were subjected to data of agitation time (3-7days). A maximum correlation coefficient value (R2) of ≤ 1 was observed for the Langmuir and PSII model. Results revealed that pH 6-7 was the best for metal sorption, while metal removal efficiency was increased by increasing temperature (298K, 303K, 308K, 313K). The results of thermodynamic study parameters (∆G°, ∆H°, ∆S°) indicated that heavy metal biosorption by Trichoderma strains was an endothermic, spontaneous, and feasible process. Moreover, surface characterization analysis through SEM, BET, FTIR, and XRD showed that T. atrobrunneum and Trichoderma sp. could adsorb more metal ions when grown in high metal concentrations. The results indicate that living biomass of T. atrobrunneum and Trichoderma sp. is an effective multi-metal biosorbent that can be used for efficacious bioremediation of bio-treatment of heavy metal polluted wastewater.

Removal of hexavalent chromium via biochar-based adsorbents: State-of-the-art, challenges, and future perspectives

Chromium originates from geogenic and extensive anthropogenic activities and significantly impacts natural ecosystems and human health. Various methods have been applied to remove hexavalent chromium (Cr(VI)) from aquatic environmental matrices, including adsorption via different adsorbents, which is considered to be the most common and low-cost approach. Biochar materials have been recognized as renewable carbon sorbents, pyrolyzed from various biomass at different temperatures under limited/no oxygen conditions for heavy metals remediation. This review summarizes the sources, chemical speciation & toxicity of Cr(VI) ions, and raw and modified biochar applications for Cr(VI) remediation from various contaminated matrices. Mechanistic understanding of Cr(VI) adsorption using different biochar-based materials through batch and saturated column adsorption experiments is documented. Electrostatic interaction and ion exchange dominate the Cr(VI) adsorption onto the biochar materials in acidic pH media. Cr(VI) ions tend to break down as HCrO4-, CrO42-, and Cr2O72- ions in aqueous solutions. At low pH (∼1-4), the availability of HCrO4- ions attributes the electrostatic forces of attraction due to the available functional groups such as -NH4+, -COOH, and -OH2+, which encourages higher adsorption of Cr(VI). Equilibrium isotherm, kinetic, and thermodynamic models help to understand Cr(VI)-biochar interactions and their adsorption mechanism. The adsorption studies of Cr(VI) are summarized through the fixed-bed saturated column experiments and Cr-contaminated real groundwater analysis using biochar-based sorbents for practical applicability. This review highlights the significant challenges in biochar-based material applications as green, renewable, and cost-effective adsorbents for the remediation of Cr(VI). Further recommendations and future scope for the implications of advanced novel biochar materials for Cr(VI) removal and other heavy metals are elegantly discussed.

Effectiveness of the engineered pinecone-derived biochar for the removal of fluoride from water

Drinking fluoride (F−)-contaminated water (>1.5 mg L−1) causes severe dental and skeletal disorders. In the central province of Pakistan, ∼20 times higher levels of F− in the drinking groundwater (compared with the 1.5 mg L−1 permissible limit of the World Health Organization) are triggering bone abnormalities in teenagers. In this study, we demonstrated the potential of pinecone-derived biochar (pristine) impregnated with Fe- and Al-salts (engineered) to defluoridate water. Batch mode adsorption experiments were carried out under variable conditions of solution pH, F− initial concentration, adsorbent dose, and contact time. The engineered biochars resulted in greater adsorption than that of pristine biochar. Specifically, the AlCl3-modified biochar exhibited a maximum adsorption capacity of 14.07 mg g−1 in spiked water and 13.07 mg g−1 in in-situ groundwater. The equilibrium isothermal and kinetic models predicted monolayer, cooperative, and chemisorption types of the adsorption process. The chemical interaction and outer-sphere complexation of F− with Al, Na, and H elements were further confirmed by the post-adsorption analysis of the AlCl3-modified biochar by FTIR and XRD. The AlCl3-modified biochar resulted in 87.13% removal of F− from the in-situ F−-contaminated groundwater, even in the presence of naturally occurring competing ions (such as Cl−, HCO3−, SO42−, and NO3−). We conclude that the AlCl3-modified biochar derived from pinecone could be a promising cost-effective adsorbent for the defluoridation of water.

Eco-friendly Elderberry based sorbent for removing Pb2+ ions from aqueous solutions

Elderberry (Sambucus nigra) pith was modified with polyethyleneimine (PEI) in order to improve the adsorption properties. Characterization of both dried Sambucus nigra pith (DSNP) and amino modification of elderberry pith with branched PEI (PEI/DSNP) was performed by: Fourier-transform infrared spectroscopy (FTIR), optical microscopy, and porosity determination. The amine and ester number, as well as acid value, were determined on DSNP and PEI/DSNP samples using standard volumetric methods. The samples were used as adsorbents for Pb2+ ions from an aqueous solution in a batch system. The obtained results were fitted using suitable equilibrium isotherm and kinetic models. The maximum adsorption capacity for Pb2+ ions on DSNP and aminаted sample, obtained using Langmuir adsorption isotherm at 298 K, are 18.9 and 47.8 mg g-1, respectively. Based on the kinetic studies, the adsorption process follows the pseudo second-order model. Thermodynamic parameters showed that the adsorption process is endothermic and spontaneous. In general, the overall adsorption process was improved by modifying starting material with branched PEI modifier by introducing large numbers of amino functionalities having high affinity to cations.

African almond (Terminalia catappa L) leaves biochar prepared through pyrolysis using H3PO4 as chemical activator for sequestration of methylene blue dye

African almond leaves (ALs) were used for the preparation of sustainable and eco-friendly adsorbent through chemical activation, followed by pyrolysis at 700 oC for adsorption of methylene blue (MB) dye from aqueous solution. Phosphoric acid activated African almond leaves biochar (PALB) was characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), pH point zero charge (pH pzc) and X-ray diffraction (XRD) techniques. The influence of various adsorption parameters was investigated for determination of optimum conditions for sequestration of MB dye. Equilibrium adsorption isotherm and kinetic models were equally assessed. Mesoporous PALB with surface area 816 m2/g and radius 1 nm has excellent removal efficiency due to removal of >98% MB dye from aqueous solution at room temperature 303 K, pH 8, initial dye concentration of 50 mg/L, adsorption dose of 0.2 g/L and contact time 30 min. Adsorption isotherm and kinetic were best fitted with Freundlich and pseudo-first order (PFO) kinetic models. Positive value of enthalpy (ΔHo) showed that the adsorption process was endothermic, while the negative value of free energy (ΔGo) suggested that the process was spontaneous and the positive value of entropy (ΔSo) indicated increase in randomness at adsorbate/adsorbent interface. PALB displayed a good monolayer adsorption capacity (Q max) of 263.95 mg/g when compared to those of other adsorbents reported in the literature for removal of MB dye from aqueous solution. This study established potential ability of PALB as eco-friendly adsorbent for adsorption of MB dye from aqueous solution.

Removal of trace DNA toxic compounds using a Poly(deep eutectic solvent)@Biomass based on multi-physical interactions

DNA toxic compounds (DNA-T-Cs), even in trace amounts, seriously threaten human health and must be completely eliminated. However, the currently used separation media face great challenges in removing trace DNA-T-Cs. Based on the functional advantages of deep eutectic solvents (DESs) and the natural features of biomass (BioM), a series of Poly(DES)@BioMs functioning as adsorbents were prepared for the removal of aromatic/hetero-atomic DNA-T-Cs at the ppm level. After optimisation of experimental conditions, the removal efficiency for DNA-T-Cs ranged from 92.4% to 96.0% with an initial concentration of 20.0 ppm, a temperature of 30 °C, duration of 30 min, and pH of 7.0. The removal processes between the DNA-T-Cs and Poly(DES)@BioMs are well described in the Temkin equilibrium and second-order kinetic adsorption models, and the desorption processes are well shown in the Korsmeryer–Peppas equilibrium and zero-order kinetic models. Molecular simulations revealed that the removal interactions include hydrogen bonding, π–π stacking, and hydrophobic/hydrophilic effects. The removal efficiency for the DNA-T-Cs at 8.0 ppm in industrial sewage ranged from 69.7% to 102%, while the removal efficiency for the DNA-T-Cs standing alone at 20.0 ppm in a methyl violet drug solution was 95.4%, confirming that the Poly(DES)@BioMs effectively removed trace DNA-T-Cs in field samples.

Metal Speciation in Water of the Flooded Mine “Arsenic” (Karelia, Russia): Equilibrium-Kinetic Modeling with a Focus on the Influence of Humic Substances

Equilibrium-kinetic modeling allows investigating metal behavior in the water–rock-organic matter system with time to evaluate anthropogenic effects on the environment. In the article, the interactions of stagnant mine drainage water of the flooded mine “Arsenic” with ore and gangue minerals were simulated using different organic matter incorporation approaches. If the model is closed to humic substances (no additional organic matter input), most fulvic acids are bound in the Fe fulvate complex. While under the removal of Fe fulvate from the model, the Cu fulvate becomes prevalent, the contribution of the fulvate complexes with Zn, Mg, and Ca also increases. This scenario simulates the organo-mineral complexes behavior well and allows identifying the sequence of metal binding to organic ligands as follows Fe > Cu > Zn > Mg > Ca. The second scenario imitates the constant input of organic matter to the model (open system regarding humic substances). The dissolved metal concentrations in the model solution are extremely high in comparison to the mine drainage water. This scenario demonstrates that excessive input of organic matter leads to the accumulation of the metals in a dissolved form and blocks the secondary mineral formation despite the faster dissolution of the primary minerals under a more acidic pH than in the first scenario. However, despite the differences between the model solution and the mine drainage water, this scenario is useful to address specific issues associated with changes in natural and anthropogenic conditions. Both scenarios show the importance of organic matter incorporation to the equilibrium-kinetic models.

Agro-based carbon for lead removal from solutions

The current study utilizes the carbon derived from the lemon peel (CLP) as an adsorbent to remove Pb (II) ions from solutions. Activation of the lemon peels was carried out by adding 1 part of the lemon peels to 1.8 parts of concentrated sulphuric acid, and well-mixed before heating the mixture at a temperature of 150 °C for 24 hours. The produced material, CLP, was employed for lead adsorption from water. A number of parameters namely, treatment times, pH, and doses of CLP were studied to assess their influence on the removability of Pb (II) by the CLP. The results indicated that the optimum contact time, pH, and dosage values for the best removal of lead were 80 min, 5, and 3 g/L respectively. To analyze the observed data gained from batch equilibrium tests, isotherm models (Freundlich and Langmuir), kinetic models (the pseudo-first-order, and the pseudo-second-order), and inter-particle diffusion using non-linear regression techniques were applied for this purpose. The obtained results proved that the equilibrium data have reasonable and good fitness and correspondence with the Freundlich isotherm models. The highest adsorption capacity and the highest removal percentage for Pb (II) were 32.98 mg/g and 99% respectively at ambient temperature.

Experimental and theoretical studies of Rhodamine B direct dye sorption onto clay-cellulose composite

Dyes are one of the main water pollutants and many biological and environmental problems are associated with them. Rhodamine B (RhB) is one of the most commonly used dye in the textile, printing, paints, and paper industry. The present work reports the sorptive removal of Rhodamine B direct dye from wastewater onto developed cellulose and clay composites. Sorbent material cellulose (48 g) was extracted from 80 g of bagasse. Then cellulose and two types of acid-activated clays were used to make efficient sorbent namely, composite I and II. Various characterization techniques were used to study the physiochemical properties of the synthesized composites. Different sorption affecting parameters were optimized such as initial dye concentration, time, temperature, pH, and composite dose for the efficient sorption of RhB onto composites. Equilibrium time was 60 min for composite-I and 80 min for composite-II Non-linear equilibrium isotherm and kinetic models demonstrated the fitness of Pseudo-second order and Redlich-Peterson isotherm. Composite-I and II removed 85.9% and 95.6% of RhB at pH 2 in 120 min, respectively. The sorption efficiency was checked, and sorbents were applied to real textile effluent which showed promising removal efficiency of over 90%. To confirm the experimental results, computational optimization and vibrational calculations were carried out using the Gaussian 09 program package with 3–21 G, 6–311 G, and 6–311+G basic sets. Geometric parameters showed the planar geometry. In the case of FTIR spectra, fundamental ring vibrations were observed with C-H and C-C. This study suggests that the developed composites have exceptional sorption ability to remove the dye contents from aqueous media.

Green Synthesized Fe3O4/Cellulose Nanocomposite Suitable Adsorbent for Metronidazole Removal

In recent decades, the need for producing adsorbents with high absorption capacity and easy separation has led to preparation of magnetic absorbents. In this study, green synthesis of iron oxide/cellulose nanocomposite was used to remove metronidazole from aquatic solutions by application of aqueous extract of spent tea waste regarding its effective and magnetic separation capability. The properties of the synthesized nanocomposite was determined by several advanced techniques, including, X-ray spectroscopy, electron microscopy imaging, thermal analysis and magnetometry. The capability of the nanocomposite adsorption in removal of metronidazole from aqueous solution was evaluated by optimizing four important parameters (pH, initial concentration of metronidazole, amount of nanocomposite and contact time). Different equilibrium isotherms and kinetic models were tested to determine the mechanism and kinetics of adsorption. X-ray diffraction patterns and electron microscopic images showed that the prepared nanocomposite had spherical particles with an average size of at least 15.5 nm. pH of 5, concentration of 10 mg/L of metronidazole, nanocomposite amount of 25 mg/L and time of 30 min were determined to form the optimal operating conditions, with the removal efficiency of 97.04%. The best model for fitting the experimental data were Langmuir isotherm with a maximum adsorption capacity of 332 mg/g and pseudo-first-order kinetic model with a constant rate of 1.15 L/min and a correlation coefficient of 0.97. The prepared nanocomposite was proposed to be studied in drug delivery systems for its high adsorption capacity, suitable magnetic properties and environmental application.

Kinetic and thermodynamic study of thionine dye adsorption by peanut hull

ABSTRACT In the present study, thionine dye was adsorbed on the surface of the peanut hull. Experiments were carried out by changing speed of agitation (50–300) rpm, time of contact (0–300) min, initial concentration of dye (10–50 mg/L), adsorbent dose (2–8 g/L), solution pH (2–12), and temperature (298–333 K) to evaluate their effect on the adsorption. The characterisation of the peanut hull was done by using XRF, FTIR and SEM. The optimum conditions were found as agitation speed = 200 rpm; time of contact = 300 min; initial dye concentration = 20 mg/L; adsorbent dose = 4 g/L; solution pH = 8 and temperature = 313 K. Equilibrium isotherm and kinetic models were studied to estimate their parameters and to predict adsorption capacity of peanut hull. Langmuir isotherm was found to be the best-fitted isotherm with R 2 of 0.992 and contributes the maximum adsorption capacity of 8.45 mg/g. Pseudo-first-order describes the kinetics with R 2 equal to 0.99. The change in enthalpy and entropy were also estimated from Gibbs’ free energy.