Effect of pH,ionic strength,foreign ions,humic acid and temperature on Zn(II) sorption onto γ-Al2O3

The sorption of Zn(II) on γ-alumina was investigated as a function of contact time, pH, ionic strength, foreign ions, solid amount, humic acid (HA) and temperature by using batch technique. The results indicated that the sorption of Zn(II) onto γ-alumina was strongly dependent on pH and ionic strength. The sorption of Zn(II) increased slowly with increasing pH at pH 2–5, then increased sharply with pH increasing from 5 to 8.5, and at last maintained a maximum value at pH>8.5. A positive effect of HA on Zn(II) sorption was found at pH<7, whereas a negative effect was observed at pH>7. The thermodynamic data (ΔG⁰, ΔS⁰, ΔH⁰) were calculated from the temperature-dependent sorption isotherms, and the results suggested that the sorption of Zn(II) on γ-alumina was endothermic and spontaneous. The sorption results revealed that the γ-alumina can be as a cost-effective sorbent for pre-concentration of Zn(II) from large volumes of aqueous solutions in environmental pollution cleanup.     

Sorption Behavior of In(III) Ions onto Cation-Exchange Carboxylic Resin in Aqueous Solutions: Batch and Column Studies

Indium and its compounds have numerous industrial applications in the manufacture of liquid crystal displays and semiconductors. They are considered hazardous substances. This article reports the research into the recovery of In(III) from aqueous solution by sorption. Cation-exchange carboxylic resin (D155 resin) was used as a sorbent for indium(III) ions extraction in this research. The factors of parameters, such as pH, kinetics, temperature and sorption isotherm, and column experiment were investigated. In batch system, D155 resin exhibited the highest In(III) ion uptake as 279 mg/g at 298 K with a pH value 5.00. The sorption data matched the Langmuir isotherms very well. The thermodynamic parameter ΔG was negative, and this result indicated that the sorption of In(III) ions on D155 resin was spontaneous. Furthermore, the positive value of ΔH showed that the sorption was endothermic in nature. In(III) ions can be eluted with 0.5 mol/L HCl solution. The Thomas model was applied to experimental column data to determine the characteristic parameters of the column which is useful for process design.     

Effect of environmental conditions on the retention behaviour of Pb(II) by hematite

BACKGROUND: The retention behaviour of Pb(II) by hematite was studied as a function of various environmental parameters such as contact time, pH, ionic strength, foreign ions, humic substances and temperature under ambient conditions. RESULTS: Pb(II) sorption on hematite was rapid and the sorption could be described by a pseudo‐second‐order model very well. The sorption of Pb(II) on hematite was strongly dependent on pH and ionic strength. The presence of humic substances enhanced the sorption of Pb(II) on hematite at low pH, but reduced Pb(II) sorption at high pH. The Langmuir model fitted the sorption isotherms of Pb(II) better than the Freundlich model at three different temperatures, 293.15, 313.15 and 333.15 K. The thermodynamic parameters (ΔH°,ΔS° and ΔG°) calculated from the temperature dependent sorption isotherms indicated that the sorption process of Pb(II) on hematite was endothermic and spontaneous. CONCLUSIONS: The results indicate that hematite is a promising candidate for the treatment of heavy metal ions from large volume solution. Copyright © 2011 Society of Chemical Industry     

Removal of Copper (II) Ions from Aqueous Solutions using Na‐mordenite

Abstract

The potential to remove copper (II) ions from aqueous solutions using Na‐mordenite, a common zeolite mineral, was thoroughly investigated. The effects of relevant parameters solution pH, adsorbent dose, ionic strength, and temperature on copper (II) adsorption capacity were examined. The sorption data followed the Langmuir, Freundlich, and Dubinin‐Radushkevich (D‐R) isotherms. The maximum sorption capacity was found to be 10.69 mg/g at pH 6, initial concentration of 40 mg/dm³, and temperature of 40°C. Different thermodynamic parameters viz., changes in standard free energy (ΔG⁰), enthalpy (ΔH⁰), and entropy (ΔS⁰) have also been evaluated and the results show that the sorption process was spontaneous and endothermic in nature. The dynamics of the sorption process were studied and the values of rate constant of adsorption, rate constant of intraparticle diffusion were calculated. The activation energy (E_a) was found to be 11.25 kJ/mol in the present study, indicating a chemical sorption process involving weak interactions between sorbent and sorbate. The interaction between copper (II) ions and Na‐mordenite is mainly attributable to ion exchange. The sorption capacity increased with the increase of solution pH and the decrease of ionic strength and adsorbent dose. The Na‐mordenite can be used to separate copper (II) ions from aqueous solutions.     

Factors Affecting on the Sorption/Desorption of Eu (III) using Activated Carbon

Abstract

The sorption and desorption of Eu (III) on H‐APC activated carbon using a batch technique has been studied as a function of carbon type, shaking time, initial pH solution, temperature, particle size of carbon, and concentration of the adsorbent and the adsorbate. The influence of different anions and cations on adsorption has been examined. The experimental data have been analyzed by Langmuir, Freundlich, and Temkin sorption isotherm models and the adsorption data for Eu (III) onto activated carbon were better correlated to the Temkin isotherm and the maximum absorption capacities obtained was 46.5 mg g^?1. Anions of phosphate, carbonate, oxalate, and acetate were found to increase the adsorption of Eu (III), whereas nitrate, chloride and all studied cations, potassium, sodium, calcium, magnesium, and aluminum have a negative effect on the adsorption capacity. More than 99% europium adsorbed on H‐APC eluted with 0.5 M HCl solution. The activated carbon prepared from apricot stone using 70% H₃PO₄ could be considered as an adsorbent that has a commercial potential for Eu (III) treatment.     

Extraction and Adsorption Behavior of Co(II) on HTTA-Impregnated Polyurethane Foam

Abstract

The batch extraction of Co(II) from aqueous solutions with open cell polyethertype HTTA-loaded polyurethane (PU) foam has been studied using a radiotracer technique. The effect of pH, shaking time, and loading capacity has been investigated. The membrane properties of loaded PU foam sorbent offer unique advantage of adsorption. The fundamental studies of adsorption show that the classical Freundlich and Langmuir isotherms are followed in the entire concentration range of a 10^?5 to 10^?2 M solution of cobalt. The sorption mean free energy from the Dubinin-Radushkevich isotherm is found to be 13.8 kJ·mol^?1 and the loading capacity 4.44 mg·g^?1, suggesting that the ion-exchange or chemisorption mechanism operates. The kinetic parameters of adsorption also support a chemisorption mechanism and the first-order rate law. The rate constants and activation energies of sorption and desorption have been evaluated. The thermodynamic function of adsorption of ΔH, ΔS, ΔG, and equilibrium constant K _c have been calculated. The process of adsorption is established to be endothermic and chemisorption, stabilized through thermodynamic functions.     

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 Traces of Selenite by Manganese Dioxide from Aqueous Solutions

Abstract

Sorption of selenite onto manganese dioxide has been investigated with respect to shaking time, concentration of sorbent and sorbate, nature of electrolyte, and influence of cations and anions. The sorption of other metal ions has been studied using optimal conditions selected for maximum sorption of selenite. The surface area, average pore diameter, porosity, and solid phase density of the sorbent have been measured. The sorption data followed only the Dubinin–Radushkevich (D–R) sorption isotherm among all the isotherms tested. The sorption capacity of 51.2 nmol·g^?1 and a constant β related to sorption energy have been estimated to be ?0.007521 mol²·kJ^?2. The sorption energy is found to be 8.15 kJ·mol^?1. The kinetics of the sorption follows the Lagergren equation in the initial stages. The first-order rate constant, k′, was evaluated to be 0.498 min^?1 and of intraparticle diffusion rate 3.06 × 10^?5 mol·g^?1·min^?2. Among all the anions and cations tested, only carbonate, Fe(III), and citrate reduced the sorption significantly. The sorption data for other metal ions showed that Te(IV) can be separated from ions showing higher degree of sorption; especially Se(IV), As(III), Sb(V), and Eu(III). It can be concluded that manganese dioxide may be used for the separation of certain metal ions, their preconcentration from very dilute solutions, and for decontamination and treatment of industrial effluents.     

Biosorption of methylene blue from aqueous solution by softstem bulrush (Scirpus tabernaemontani Gmel.)

BACKGROUND: The removal of methylene blue from aqueous solution was studied using softstem bulrush (Scirpus tabernaemontani Gmel.) as the biosorbent. The effects of various parameters including contact time, biosorbent dosage, ionic strength and solution pH on the biosorption were investigated. RESULTS: The sorption capacity increased with an increase in biosorbent dosage and a decrease in ionic strength. The equilibrium time was found to be 240 min for full equilibration. Pseudo‐first‐order, pseudo‐second‐order, Bangham equation and intraparticle diffusion models were applied to fit the kinetic data, and the results showed that the sorption process followed the pseudo‐second‐order model. Equilibrium data conformed to Langmuir and Redlich–Peterson isotherm models, with a maximum monolayer biosorption capacity of 53.8 mg g^?1 for the Langmuir isotherm at 18 °C. The value of ΔG was estimated to be ? 29.24 kJ mol^?1, indicating the spontaneous nature of the biosorption. The biosorption process was strongly pH‐dependent and favourable at alkaline pH. CONCLUSION: Softstem bulrush, which is readily available and inexpensive, could be employed as a promising biosorbent for the removal of dye. Copyright © 2008 Society of Chemical Industry     

Haematoxylin sorption onto yak hair: kinetic and thermodynamic studies

The kinetic and thermodynamic behaviours of haematoxylin sorption onto yak hair as a model system were investigated. It was found that the sorption kinetics of haematoxylin on hair followed a pseudo‐second‐order kinetic model. The equilibrium sorption capacity increased as the temperature increased from 303 to 313 K, but dropped gradually as the temperature increased beyond 313 K. The maximum equilibrium sorption capacity was 24.04 mg g^?1 at T = 313 K. Meanwhile, the sorption isotherm data were ingood agreement with the Freundlich isotherm, presenting high coefficients (R² > 0.99). The free energy change (ΔG), enthalpy change (ΔH), and entropy change (ΔS) terms for haematoxylin dyeing were also determined, the negative values of ΔG and ΔH obtained indicated that the haematoxylin dye sorption process is a spontaneous and an exothermic one. Also, positive values of ΔS showed an increase in disorder of the system of haematoxylin sorption onto hair. Haematoxylin could be a good candidate as a natural green dye for hair fibre.     

Enhanced and selective fluoride sorption on Ce(III) encapsulated chitosan polymeric matrix

Chitosan beads (CB) possesses low defluoridation capacity (DC) have been suitably modified by carboxylation followed by chelation with Ce(III) to enhance its DC. The carboxylated chitosan beads (CCB), which has a desirable DC of 1385 mgF^?/kg, has been further chemically modified by incorporating Ce³⁺ ion into CCB (Ce‐CCB) and its DC was found to be 4798 mgF^?/kg, whereas raw chitosan beads (CB) possesses 52 mgF^?/kg only. The maximum DC of Ce‐CCB was observed at pH 7 and showed selectivity toward fluoride in presence of other coanions. The sorbent was characterized using FTIR and SEM with EDAX analysis. The sorption data was fitted with Freundlich and Langmuir isotherms and kinetic models. The calculated thermodynamic parameters, viz., ΔG°, ΔH° and ΔS° indicate the nature of fluoride sorption. A field trial was carried out with fluoride water collected from a nearby fluoride‐endemic village to test the suitability of Ce‐CCB at field conditions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

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     

Kinetics and Equilibrium Studies for the Removal of Cobalt,Manganese, and Silver in Ethanol using Dowex 50W-x8 Cation Exchange Resin

Organic solvents such as ethanol, find a wide range of applications in fuel, pharmaceutical industries, food industries, and paint formulations, among others. The removal of Ag(I), Co(II), and Mn(II) ions in ethanol by cation exchange resin, Dowex 50W-x8, was investigated. The adsorption characteristics of metal ions onto Dowex 50W-x8 resin were described by Langmuir isotherms. The maximum sorption exchange capacities at 298 K were obtained as 47.4 mg g^?1, 52.6 mg g^?1, and 58.5 mg g^?1 for Ag(I), Co(II), and Mn(II), respectively. The data was also fitted to Temkin and Dubinin-Radushkevich adsorption isotherm models to evaluate other adsorption properties. The ion exchange of silver, cobalt, and manganese on cation exchange resin followed pseudo-second-order kinetics, and the intraparticle diffusion was rate-determining step. The thermodynamic parameters indicated that the sorption of metal ions onto Dowex 50W-x8 resin was spontaneous (negative ΔG°) and endothermic in nature (positive ΔH°) implying that the adsorption capacity increased with increasing temperature. The resin can be regenerated by eluting metal ions with 3.0 mol L^?1 HNO₃ followed by washing it with 10 mL of Millipore water and 10 mL of 2.0 M NaOH, respectively. The proposed method was applied for metal ion removal in real ethanol samples.     

Evaluation of the Influence of Environmental Conditions on the Removal of Pb(II) from Wastewater by Ca-rectorite

The removal of Pb(II) from wastewater by Ca-rectorite was investigated as various environmental factors containing contact time, pH, ionic strength, solid content, coexisting ions, humic acid (HA), and temperature. The kinetic sorption of Pb(II) on Ca-rectorite was well described by the pseudo second-order model. The sorption process was strongly dependent on pH and ionic strength. The results indicated that the presence of HA and coexisting ions influenced the sorption of Pb(II) on Ca-rectorite obviously. Besides, the Langmuir and Freundlich models were employed to simulate the sorption isotherms. The thermodynamic parameters indicated that the sorption process was spontaneous and endothermic. It is possible to conclude that Ca-rectorite has a good potential for disposal of lead-contaminated wastewater.     

Synthesis and characterization of CMC/MMT nanocomposite for Cu<Superscript>2+</Superscript> sequestration in wastewater treatment

Organic–inorganic hybrid nanocomposites are promising materials for remediation of pollutants from wastewater, as they exhibit the unique characteristics of both inorganic and organic materials. In this study, carboxymethyl cellulose/montmorillonite Nanocomposite (CMC/MMT-NC) was prepared and applied for Cu²⁺ sequestration. CMC/MMT-NC was characterized by FTIR and SEM before and after the sequestration process, indicating fundamental changes in surface morphology after treatment experiments. The parameters affecting the process such as pH, contact time, CMC/MMT-NC mass, Cu²⁺ concentration and temperature were experimentally adjusted. Statistical regression variables (R², RMSE, RSS, F-Value and P-Value) were calculated to predict the best-applied isotherm, kinetic and thermodynamic modeling. Freundlich isotherm model successfully described the equilibrium data, which implies a multilayer adsorption process. Kinetic results were well fitted to pseudo-second-order kinetic model. Intraparticle diffusion (IPD) model showed the control of the boundary layer moreover, IPD model cannot be accepted as the only rate-determining step. The apparent activation energy (Ea) was 35.65 kJ/mol, which revealed a physisorption process. The thermodynamic study in means of ΔG⁰, ΔH⁰, and ΔS⁰ demonstrated the feasibility, spontaneity and exothermicity of Cu²⁺ sequestration. Application study confirmed the efficiency of CMC/MMT nanocomposite to remediate Cu²⁺ from synthetic and natural polluted seawater.     

Physicochemical Aspects on Fluoride Adsorption for Removal from Water by Synthetic Hydrous Iron(III) – Chromium(III) Mixed Oxide

Fluoride removal with varying different parameters at 303 ± 1.6 K and pH 6.5 ± 0.2 was investigated by hydrous iron(III)-chromium(III) bimetal oxide. The kinetic and equilibrium data fitted with the pseudo-second order and Langmuir isotherm equations very well (R² = 0.99?1.00), respectively. The Langmuir capacity (θ) and free energy (E_DR) of adsorption evaluated were 16.34 (±0.50) mg·g^?1 and 15.81 kJ·mol^?1, respectively. The estimated thermodynamic parameters viz. ΔH⁰, ΔG⁰, and ΔS⁰ indicated that the reaction was endothermic but spontaneous for entropy increase. The small-scale column filtration of high fluoride (C₀ = 7.37 mg·L^?1) water gave encouraging results.     

Thermodynamics,kinetics, and isotherms studies for gold(III) adsorption using silica functionalized by diethylenetriaminemethylenephosphonic acid

A novel hybrid material silica gel chemically modified by diethylenetriaminemethylenephosphonic acid GH-D-P has been developed and characterized. The results of the adsorption thermodynamics and kinetics of the as-synthesized GH-D-P for Au(III) showed that this high efficient inorganic–organic hybrid adsorbent had good adsorption capacity for Au(III), and the best interpretation for the experimental data was given by the Langmuir isotherm equation, the maximum adsorption capacity for Au(III) is 357.14 mg/g at 35 °C. Moreover, the study indicated the adsorption kinetics of GH-D-P could be modeled by the pseudo-second-order rate equation wonderfully, and the adsorption thermodynamic parameters ΔG, ΔH and ΔS were −20.43 kJ mol⁻¹, 9.17 kJ mol⁻¹, and 96.24 J K⁻¹ mol⁻¹, respectively. Therefore, the high adsorption capacity make this hybrid material have significant potential for Au(III) uptake from aqueous solutions using adsorption method.     

Selective Adsorption of Palladium(II) Complexes onto the Chelating Ion Exchange Resin Dowex M 4195 – Kinetic Studies

The chelating ion exchange resin – Dowex M 4195 was used in palladium(II) complexes adsorption from the acidic solutions. This study discusses the sorption kinetics, and more specifically the interparticle diffusion behavior of palladium(II) onto Dowex M 4195. The adsorption studies were used to determine the amount of palladium(II) complexes uptake (resin loading), the distribution coefficients, and the recovery efficiency of Pd(II) complexes. The influence of the agitation speed, the beads size (mean radius of swollen particles), the palladium concentrations, as well as acid concentrations (ionic strength of solutions), the macrocomponent addition (sodium chloride), and the phases contact time was also discussed. Moreover, the effect of temperature was taken into account during the determination of the isotherms. The experimental data obtained at 100 µg/cm³ Pd(II) initial concentration were applied to the kinetic models, and the sorption parameters as well as the normal standard deviation were calculated. Moreover, the Langmuir, Freundlich, and Tempkin‐Pyzhev isotherm models were applied and the isotherms parameters were calculated.     

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.     

Kinetics and Equilibrium Sorption Models: Fitting Plutonium,Strontium, Uranium,and Neptunium Loading on Monosodium Titanate (MST)

Abstract

The Dubinin‐Astashov (DA) isotherm parameters for U, Pu, Sr, and Np have been updated to include additional data obtained since the original derivation. The DA isotherms were modified to include a kinetic function derived by Rahn to describe sorbate loading from the beginning of sorption up to steady state. The final functions describe both kinetic and thermodynamic sorption.