Sorption of Brilliant Red HE-3B Reactive Dye from Aqueous Solution onto Seashells Waste: Equilibrium and Kinetic Studies

The potential of waste seashells powder, as a new adsorbent for Brilliant Red HE-3B reactive dye removal from aqueous solutions, was examined by the batch technique. The Freundlich, Langmuir, and Dubinin-Radushkevich adsorption models were applied to describe the equilibrium sorption data and to determine the corresponding isotherm constants. The values of the thermodynamic parameters, ΔG, ΔH, and ΔS, indicate that the sorption of reactive dye is a spontaneous and endothermic process. The kinetic data evaluated by pseudo-first order, pseudo-second order, and intraparticle diffusion kinetic models suggested that the sorption of reactive dye onto seashell is a complex process and both surface sorption and intraparticle diffusion contributes to the rate limiting step.     

Effect of Temperature on Kinetics and Adsorption Profile of Endothermic Chemisorption Process: –Tm(III)–PAN Loaded PUF System

Abstract

The sorption behavior of 3.18×10^?6 mol l^?1 solution of Tm(III) metal ions onto 7.25 mg l^?1 of 1‐(2‐pyridylazo)‐2‐naphthol (PAN) loaded polyurethane foam (PUF) has been investigated at different temperatures i.e. 303 K, 313 K, and 323 K. The maximum equilibration time of sorption was 30 minutes from pH 7.5 buffer solution at all temperatures. The various rate parameters of adsorption process have been investigated. The diffusional activation energy (ΔE_ads) and activation entropy (ΔS_ads) of the system were found to be 22.1±2.6 kJ mol^?1 and 52.7±6.2 J mol^?1 K^?1, respectively. The thermodynamic parameters such as enthalpy (ΔH), entropy (ΔS), and Gibbs free energy (ΔG) were calculated and interpreted. The positive value of ΔH and negative value of ΔG indicate that sorption is endothermic and spontaneous in nature, respectively. The adsorption isotherms such as Freundlich, Langmuir, and Dubinin–Radushkevich isotherm were tested experimentally at different temperatures. The changes in adsorption isotherm constants were discussed. The binding energy constant (b) of Langmuir isotherm increases with temperature. The differential heat of adsorption (ΔH_diff), entropy of adsorption (ΔS_diff) and adsorption free energy (ΔG_ads) at 313 K were determined and found to be 38±2 kJ mol^?1, 249±3 J mol^?1 K^?1 and –40.1±1.1 kJ mol^?1, respectively. The stability of sorbed complex and mechanism involved in adsorption process has been discussed using different thermodynamic parameters and sorption free energy.     

Uptake of aromatic solvents by polyethylene films

The sorption properties of the solvents benzene, toluene, and xylene in polyethylene films at 40, 60, and 80°C were investigated. The diffusion coefficient increased with an increase in the sorption temperature for the solvents and was highest for xylene and least for benzene. The inability of xylene to show a definite order of the diffusion coefficients at the investigated temperatures was attributed to the presence of two methyl side groups in the molecule. The solubilities of the solvents in polyethylene increased with an increase in the sorption temperature, and the following order of the solubilities could be observed: xylene > toluene > benzene. The permeabilities of the solvents in polyethylene depended on the sorption temperature, and the following order of the permeabilities was observed: xylene > toluene > benzene. The calculated activation energies of sorption in polyethylene films were all positive; benzene had the highest energy of sorption, and xylene had the lowest. The calculated enthalpies of sorption (ΔH_S) were also positive for the three solvents and were in the following order: xylene > toluene > benzene. The calculated entropies of sorption (ΔS) were negative for the solvents and showed trends similar to the variation of ΔH_S among the solvents. The change in the Gibbs free energies of sorption (ΔG_S), evaluated with the expression ΔG_S = ΔH_S ? TΔS (where T is the Kelvin temperature), were all positive, and this was an indication of the nonspontaneity of the solubility of polyethylene in the aromatic solvents at 313 K. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3849–3854, 2007     

Kinetic and Equilibrium Studies on the Adsorption of Crystal Violet Dye using Kaolin as an Adsorbent

Abstract

Experimental investigations are carried out to adsorb toxic crystal violet dye from aqueous medium using kaolin as an adsorbent. Characterization of kaolin is done by measuring

1. particle size distribution using particle size analyzer,

2. BET surface area using BET surface analyzer,

3. structural analysis using X ray diffractometer, and

4. microscopic analysis using scanning electron microscope.

The effects of initial dye concentration, contact time, kaolin dose, stirring speed, pH, and temperature are studied for the adsorption of crystal violet in batch mode. Adsorption experiments indicate that the extent of adsorption is strongly dependent on the pH of the solution. Free energy of adsorption (ΔG ^o ), enthalpy (ΔH ^o ), and entropy (ΔS ^o ) changes are calculated to know the nature of adsorption. The calculated values of ΔG ^o are ?4.11 and ?4.48 kJ/mol at 295 K and 323 K, respectively, for 20 mg/L of dye concentration, which indicates that the adsorption process is spontaneous. The estimated values of ΔH ^o and ΔS ^o show the negative and positive sign, respectively, which indicate that the adsorption process is exothermic and the dye molecules are organized on the kaolin surface in more random fashion than in solution. The adsorption kinetic has been described by pseudo first order, pseudo second order and intra‐particle diffusion models. It is observed that the rate of dye adsorption follows pseudo second order model for the dye concentration range studied in the present case. Standard adsorption isotherms are used to fit the experimental equilibrium data. It is found that the adsorption of crystal violet on kaolin follows the Langmuir adsorption isotherm.     

Removal of Basic Blue 3 by sorption onto a weak acid acrylic resin

A weak acid acrylic resin was used as an adsorbent for the investigation of Basic Blue 3 (BB3) adsorption kinetics, isotherms, and thermodynamic parameters. Batch adsorption studies were carried out to evaluate the effect of pH, contact time, initial concentration (28–100 mg/g), adsorbent dose (0.05–0.3 g), and temperature (290–323 K) on the removal of BB3. The adsorption equilibrium data were analyzed by the Langmuir, Temkin, and Freundlich isotherm models, with the best fitting being the first one. The adsorption capacity (Q_o) increased with increasing initial dye concentration, adsorbent dose, and temperature; the highest maximum Q_o (59.53 mg/g) was obtained at 323 K. Pseudo‐first‐order and pseudo‐second‐order kinetic models and intraparticle diffusion models were used to analyze the kinetic data; good agreement between the experimental and calculated amounts of dye adsorbed at equilibrium were obtained for the pseudo‐second‐order kinetic models for the entire investigated concentrations domain. Various thermodynamic parameters, such as standard enthalpy of adsorption (ΔH^o = 88.817 kJ/mol), standard entropy of adsorption (ΔS^o = 0.307 kJ mol^?1 K^?1), and Gibbs free energy (ΔG^o < 0, for all temperatures investigated), were evaluated and revealed that the adsorption process was endothermic and favorable. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Biosorptive Removal of Ni(II) from Aqueous Solution by Caesalpinia bonducella Seed Powder

The present work deals with the use of Caesalpinia bonducella seed powder (CBSP) as a biosorbent for Ni(II) removal from aqueous solution. The nature and morphology of the sorbent were determined using FTIR spectral, SEM, and EDX analysis. The biosorption characteristics of Ni(II) onto CBSP was investigated as a function of pH, biosorbent dosage, contact time, initial metal ion concentration, and temperature. Langmuir and Freundlich isotherms were used to fit the experimental data. The best interpretation for the equilibrium data was given by the Langmuir isotherm. The maximum biosorption capacity was found to be 188.7 mg/g for Ni(II) at pH 5.0 and at 323 K. The equilibrium biosorption data were well fitted with the pseudo-second-order kinetic equation. The values of thermodynamic parameters (ΔG^o, ΔH^o, and ΔS^o) indicated that the biosorption of Ni(II) onto CBSP was feasible, spontaneous and exothermic in nature. The FTIR results revealed that hydroxyl, amine, carboxyl, and carbonyl functional groups are responsible for Ni(II) biosorption onto CBSP.     

Kinetic and thermodynamic study of Eu(III) sorption on natural red earth in South China

We did a kinetic and thermodynamic study of Eu(III) sorption on natural red earth (NRE) in South China as a function of contact time, pH values, ionic strength, humic acid (HA) and temperature under ambient conditions. Linear and nonlinear regression methods in selecting the optimum sorption isotherm were applied on the experimental data. The results suggest that sorption of Eu(III) on NRE can be described by a pseudo-second-order rate equation and strongly dependent on ionic strength at pH<7. Sorption of Eu(III) on NRE increased with increasing temperature, two-parameter and three-parameter isotherms were applied to analysis the equilibrium adsorption data, and a comparison of linear and nonlinear regression methods was done. The thermodynamic parameters (ΔH⁰, ΔS⁰ and ΔG⁰) of Eu(III) sorption on NRE at different temperatures were calculated from the temperature-dependent sorption isotherms, indicating that the sorption process of Eu(III) was spontaneous. The results showed that the nonlinear method is a better way to obtain the isotherm parameters and the data were in good agreement with the Freundlich isotherm model.     

Equilibrium,Thermodynamic, and Kinetic Studies on Trichoderma viride Biomass as Biosorbent for the Removal of Cu(II) from Water

Equilibrium, thermodynamic, and kinetic studies on the biosorption of Cu(II) using biomass, Trichoderma viride were carried out. The biosorbent was characterized by Fourier transform infrared spectroscopy and Scanning Electron Microscopy. The Langmuir and Freundlich isotherm models were applied to describe the biosorption process. The influence of pH, the biomass dosage, the contact time, the initial metal ion concentration, and the temperature of the solution on the biosorption was studied. The maximum Cu(II) biosorption was attained at pH 5. The equilibrium data were better fit by the Langmuir isotherm model than by the Freundlich isotherm. The maximum biosorption capacity of T. viride biomass was found to be 19.6 mg/g for Cu(II). The kinetic studies indicated that the biosorption of Cu(II) followed the pseudo-second-order model. The calculated thermodynamic parameters, Gibbs-free energy (ΔG^o), enthalpy (ΔH^o), and entropy (ΔS^o) showed that the biosorption of Cu(II) onto T. viride biomass was spontaneous and endothermic. It can be concluded that the T. viride biomass has the potential as an effective and low-cost biosorbent for Cu(II) removal from aqueous solutions.     

Removal of Neutral Red from aqueous solution by using modified hectorite

The object of this work was to study the modified hectorite as effective adsorbent for Neutral Red (NR) from aqueous solution. The adsorbent capacity of modified hectorite was discussed. The effects of surfactant content, adsorbent content, pH and adsorption temperature on the sorption of NR on modified hectorite were studied. Experimental results showed that the equilibrium adsorption data fitted well with Langmuir isotherm and the adsorption capacity was 393.70 mg/g for the modified cetylpyridinium bromide hectorite (CPB-Hect). Kinetic studies showed that the dynamical data fitted well with the pseudo-second-order kinetic model. For thermodynamic studies, parameters such as the Gibbs free energy (ΔG⁰), the enthalpy (ΔH⁰) and the entropy (ΔS⁰) indicated that the adsorption process was spontaneous and endothermic in nature.     

Removal of Cr(VI) From Aqueous Solution by Turkish Vermiculite: Equilibrium,Thermodynamic and Kinetic Studies

Abstract

The adsorption of Cr(VI) from aqueous solution by Turkish vermiculite were investigated in terms of equilibrium, kinetics, and thermodynamics. Experimental parameters affecting the removal process such as pH of solution, adsorbent dosage, contact time, and temperature were studied. Equilibrium adsorption data were evaluated by Langmuir, Freundlich and Dubinin–Radushkevich (D–R) isotherm models. Langmuir model fitted the equilibrium data better than the Freundlich model. The monolayer adsorption capacity of Turkish vermiculite for Cr(VI) was found to be 87.7 mg/g at pH 1.5, 10 g/L adsorbent dosage and 20°C. The mean free energy of adsorption (5.9 kJ/mol) obtained from the D–R isotherm indicated that the type of sorption was essentially physical. The calculated thermodynamic parameters (ΔG ^o , ΔH ^o and ΔS ^o ) showed that the removal of Cr(VI) ions from aqueous solution by the vermiculite was feasible, spontaneous and exothermic at 20–50°C. Equilibrium data were also tested using the adsorption kinetic models and the results showed that the adsorption processes of Cr(VI) onto Turkish vermiculite followed well pseudo-second order kinetics.     

EFFECT OF TEMPERATURE ON THE ADSORPTION OF METHYLENE BLUE DYE ONTO SULFURIC ACID–TREATED ORANGE PEEL

The present study explains the preparation and application of sulfuric acid–treated orange peel (STOP) as a new low-cost adsorbent in the removal of methylene blue (MB) dye from its aqueous solution. The effects of temperature on the operating parameters such as solution pH, adsorbent dose, initial MB dye concentration, and contact time were investigated for the removal of MB dye using STOP. The maximum adsorption of MB dye onto STOP took place in the following experimental conditions: pH of 8.0, adsorbent dose of 0.4 g, contact time of 45 min, and temperature of 30°C. The adsorption equilibrium data were tested by applying both the Langmuir and Freundlich isotherm models. It is observed that the Freundlich isotherm model fitted better than the Langmuir isotherm model, indicating multilayer adsorption, at all studied temperatures. The adsorption kinetic results showed that the pseudo-second-order model was more suitable to explain the adsorption of MB dye onto STOP. The adsorption mechanism results showed that the adsorption process was controlled by both the internal and external diffusion of MB dye molecules. The values of free energy change (ΔG ^o) and enthalpy change (ΔH ^o) indicated the spontaneous, feasible, and exothermic nature of the adsorption process. The maximum monolayer adsorption capacity of STOP was also compared with other low-cost adsorbents, and it was found that STOP was a better adsorbent for MB dye removal.     

Removal of Cr (VI) from aqueous solution by newspapers

The potential to remove Cr (VI) ions from aqueous solution using newspapers was investigated in the present study. The effects of relevant parameters such as solution pH, adsorbent concentration, and reaction temperature on Cr (VI) adsorption were examined. The adsorption of Cr (VI) ions onto newspapers was found to be highly pH-dependent and the highest uptake occurred at pH 1.0. The sorption equilibrium data were correlated to the Langmuir, Freundlich, Redlich-Peterson and Dubinin-Radushkevich equations. Five different non-linear error functions were examined and the result indicated that the Freundlich and Redlich-Peterson equations better fitted the equilibrium data than Langmuir isotherm. The maximum sorption capacity was found to be 55.06 mg/g at pH 1.0, adsorbent concentration 4 g/L and reaction temperature of 30 °C. Different thermodynamic parameters viz., changes in standard free energy (ΔG⁰), enthalpy (ΔH⁰) and entropy (ΔS⁰) were also evaluated and the results show that the sorption process was spontaneous and endothermic in nature. The kinetic experimental data were well fitted by the pseudo-second order, external film diffusion and diffusion models allowing the corresponding parameters to be evaluated. The sorption capacity increased with the decrease of adsorbent concentration.     

Investigation of α‐iron oxide‐coated polymeric nanocomposites capacity for efficient heavy metal removal from aqueous solution

In the present study, PS@α‐Fe₂O₃ nanocomposites were prepared by chemical microemulsion polymerization approach and the ability of magnetic beads to remove Cu(II) ions from aqueous solutions in a batch media was investigated. Various physico‐chemical parameters such as pH, initial metal ion concentration, temperature, and equilibrium contact time were also studied. Adsorption mechanism of Cu²⁺ ions onto magnetic polymeric adsorbents has been investigated using Langmuir, Freundlich, Sips and Redlich–Petersen isotherms. The results demonstrated that the PS@α‐Fe₂O₃ nanocomposite is an effective adsorbent for Cu²⁺ ions removal. The Sips adsorption isotherm model (R² > 0.99) was more in consistence with the adsorption isotherm data of Cu(II) ions compared to other models and the maximum adsorbed amount of copper was 34.25 mg/g. The adsorption kinetics well fitted to a pseudo second‐order kinetic model. The thermodynamic parameters (ΔH°, ΔS°, and ΔG°) were calculated from the temperature dependent sorption isotherms, and the results suggested that copper adsorption was a spontaneous and exothermic process. POLYM. ENG. SCI., 55:2735–2742, 2015. © 2015 Society of Plastics Engineers     

Preparation and characterization of aluminum pillared K10 and KSF for adsorption of trimethoprim

Montmorillonite KSF and K10 were used as precursor materials for synthesis of aluminum pillared K10 and KSF (Al-K10 and Al-KSF) which characterized by TGA, XRD, SEM and FT-IR spectroscopic analysis. The sorption of trimethoprim (TMP) which is commonly employed as an antibiotic onto Al-K10 and Al-KSF was also investigated as a function of adsorbent dosage, solution pH, contact time and temperature. The adsorption kinetics was interpreted using pseudo-first-order, pseudo-second-order kinetic models and intraparticle diffusion model. The pseudo-second-order model provided the best correlation. Adsorption isotherm parameters were obtained from Freundlich, Langmuir and Dubinin–Radushkevich (DR) isotherm models. Adsorption of TMP onto Al-K10 and Al-KSF was physical in nature and ion-exchange mechanism for DR equation, respectively. Al-K10 exhibits higher removal capacity at lower adsorbent dosages in comparison with Al-KSF. The removal capacity was increased by increasing pH. ΔH⁰, ΔS⁰ and ΔG⁰ showed that adsorption of trimethoprim was endothermic, increasing randomness and not spontaneous in nature.     

Adsorptive removal of cationic dye from aqueous solutions by ZnO/ZnMn2O4 nanocomposite

The ZnO/ZnMn₂O₄ nanocomposite (ZnMn) was used as adsorbent for the removal of cationic dye Basic Yellow 28 (BY28) from aqueous solutions. The adsorbent was characterized by X-ray diffraction, scanning electron microscope, TEM, Fourier transform infrared ray, BET, particle size distribution and zeta potential measurements. The adsorption parameters, such as temperature, pH and initial dye concentration, were studied. Kinetic adsorption data were analyzed using the pseudo-first-order, pseudo-second-order and intraparticle diffusion kinetic models. The Langmuir and Freundlich isotherm models were applied to fit the equilibrium data. The maximum adsorption capacity of BY28 was 48.8 mg g^?1. Various thermodynamic parameters, such as ΔG°, ΔH° and ΔS°, were calculated.     

Biosorption of a Basic Dye from Aqueous Solutions by Euphorbia rigida

Abstract

In this study, the biosorption of Basic Blue 9 (BB9) dye from aqueous solutions onto a biomass of Euphorbia rigida was examined by means of the initial biosorbate concentration, biosorbent amount, particle size, and pH. Biosorption of BB9 onto E. rigida increases with both the initial biosorbate concentration and biosorbent amount, whereas decreases with the increasing particle size. The experimental data indicated that the biosorption isotherms are well‐described by the Langmuir equilibrium isotherm equation at 20, 30, and 40°C. Maximum biosorption capacity was 3.28×10^?4 mol g^?1 at 40°C. The biosorption kinetics of BB9 obeys the pseudo‐second‐order kinetic model. The thermodynamic parameters such as ΔG°, ΔH° and ΔS° were calculated to estimate the nature of biosorption. These experimental results have indicated that E. rigida has the potential to act as a biosorbent for the removal of Basic Blue 9 from aqueous solutions.     

Adsorption of Furfural from Aqueous Solution onto Activated Carbon: Kinetic,Equilibrium and Thermodynamic Study

Abstract

The present study aims to evaluate the influence of various experimental parameters viz. initial pH (pH ₀), adsorbent dose, contact time, initial concentration and temperature on the adsorptive removal of furfural from aqueous solution by commercial grade activated carbon (ACC). Optimum conditions for furfural removal were found to be pH ₀ ≈ 5.9, adsorbent dose ≈ 10 g/l of solution and equilibrium time ≈ 6.0 h. The adsorption followed pseudo‐second‐order kinetics. The effective diffusion coefficient of furfural was of the order of 10^?13 m²/s. Furfural adsorption onto ACC was found to be best represented by the Redlich‐Peterson isotherm. A decrease in the temperature of the operation favorably influenced the adsorption of furfural onto ACC. The positive values of the change in entropy (ΔS ⁰); and the negatived value of heat of adsorption (ΔH ⁰) and change in Gibbs free energy (ΔG ⁰) indicated feasible, exothermic, and spontaneous nature of furfural adsorption onto ACC.     

Kinetic Modeling Study on Methylene Blue Sorption onto Agave americana fibers: Fractal Kinetics and Regeneration Studies

Kinetics sorption study was carried out with varying pH, concentration, and temperature to determine the potential of Agave americana fiber for the removal of methylene blue. The thermodynamic properties (ΔG°, ΔH° and ΔS°) were determined. In order to investigate the sorption mechanisms, kinetic parameters were determined using the Lagergren, the pseudo-second order and the recently established fractal kinetic equations. The experimental kinetics data have been fitted with the non linear form of the new Brouers sotolongo kinetic model. Fractal kinetic equation gives higher correlation coefficients, indicating that this model can be considered accurate for describing the sorption methylene blue kinetics.     

Coconut (Cocos nucifera) Shell Based Activated Carbon for the Removal of Malachite Green Dye from Aqueous Solutions

The adsorption of malachite green (MG) dye using coconut shell based activated carbon (CSAC) was investigated. Operational factors such as the effect of pH, initial dye concentration, adsorbent dosage, contact time, and solution temperature on the adsorption process were studied. Solution pH strongly affected the chemistry of both the dye molecule and CSAC in solution. Optimum dye removal was obtained at pH ≥ 8.0. Equilibrium was reached in 120 minutes contact time. The Langmuir, Freundlich, and Dubinin–Radushkevich (D-R) isotherm models were used to evaluate the adsorption data. The adsorption data fitted the Langmuir model most with maximum adsorption monolayer coverage of 214.63 mg/g. Pseudo-first-order, pseudo second-order, and intraparticle diffusion models were also used to fit the experimental data. Kinetic parameters, rate constants, equilibrium sorption capacities, and related correlation coefficients, for each model were calculated and discussed. Thermodynamic parameters such as ΔG⁰, ΔH⁰, and ΔS⁰ were evaluated and it was found that the sorption process was feasible, spontaneous, and exothermic in nature. The mean free energy obtained from D-R isotherm suggests that the adsorption process follows physiosorption mechanism. The results showed that coconut shells could be employed as a low-cost precursor in activated carbon preparation for the removal of MG dye from wastewaters.