Personal Research Database

Full Text: 2007\Sep Sci Tec42, 3363.pdf

Abstract: The extent of the methylene blue (MB) adsorption from an aqueous solution is a convenient indicator in the evaluation of activated carbons. The adsorption of MB (cationic dye) from aqueous solution has been studied using twenty activated carbons. The activated carbons were prepared from acid-precipitated eucalyptus kraft lignin following a two-step process consisting of CO₂ partial gasification after carbonization in N₂ atmosphere. The adsorbed amount was studied as a function of the contact time, temperature, pH, concentration of adsorbate, and burn-off of the activated carbons. The equilibria results obtained in a batch contactor were fitted by the Langmuir equation. The calculated values of Delta G demonstrate that the adsorption of the dye onto these activated carbons occurs by physical adsorption. Both the apparent values of Delta H and Delta S are positive, indicating that the adsorption process is endothermic and can produce spontaneously in our experimental conditions. The kinetic study was developed using a second-order exponential decay equation and the results were correlated using the Lagergren first-order equation relative to the concentration on the solid phase. The intraparticle diffusion coefficients have been estimated on the basis of an internal diffusion controlling mechanism for the net adsorption rate.

Keywords: Activated Carbon, Adsorption, Adsorption Equilibrium, Adsorption Kinetics, Aqueous-Solutions, Chinese Coal, Equilibrium, Eucalyptus Kraft Lignin, Kinetics, Liquid Phase Application, Malachite Green, Methylene Blue, Methylene-Blue, Reactive Dyes, Removal, Waste-Water

? Bhattacharyya, K.G. and Sen Gupta, S. (2007), Adsorption of Co(II) from aqueous medium on natural and acid activated Kaolinite and montmorillonite. Separation Science and Technology, 42 (15), 3391-3418.

Full Text: 2007\Sep Sci Tec42, 3391.pdf

Abstract: Hazardous metal cations enter water through the natural geochemical route or from the industrial wastes. Their separation and removal can be achieved by adsorptive accumulation of the cations on a suitable adsorbent. In the present work, toxic Co(II) ions are removed from water by accumulating them on the surface of clay minerals. Clay adsorbents are obtained from kaolinite, montmorillonite, and their acid activated forms, and are characterized with the measurement of XRD patterns, specific surface area, and cation exchange capacity. The adsorption experiments are carried out in a batch process in environments of different pH, initial Co(II) concentration, amount of clay, interaction time, and temperature. Adsorption of Co(II) on the clays increases continuously from pH 1.0 to 8.0 after which adsorption could not be carried out due to the decreasing solubility of Co(II). Under appropriate conditions, the adsorption of Co(II) is very fast at low coverage approaching equilibrium within 240 min and the interactions are best described by second order kinetics. Langmuir monolayer capacity has been computed in the range of 11.2 to 29.7 mg/g and Co(II) accumulation has the order of acid-activated montmorillonite > montmorillonite > acid activated kaolinite > kaolinite. Adsorption of Co(II) on kaolinite and acid-activated kaolinite is endothermic driven by entropy increase but the same process follows exothermically on montmorillonite and acid-activated montmorillonite supported by entropy decrease. In both cases, spontaneous adsorptive accumulation is ensured by favorable Gibbs energy decrease. It is found that acid activation enhances the adsorption capacity of kaolinite and montmorillonite.

Keywords: Acid-Activation, Adsorption, Bentonite, Cadmium, Clays, Copper, Heavy-Metals, Kaolinite, Kinetics, Low-Cost Adsorbents, Montmorillonite, Nickel Ions, Removal, Sorption, Waste-Waters

? Hosseini, M.S., Hosseini, M. and Bandeh-Gharaei, A.H. (2007), Solvent impregnated resins containing quinizarin: Preparation and application to batch-mode separation of Cd(II), Cu(II), Ni(II), and Zn(II) in aqueous media prior to the determination by flame atomic absorption spectrometry. Separation Science and Technology, 42 (15), 3465-3480.

Full Text: 2007\Sep Sci Tec42, 3465.pdf

Abstract: Preparation of a high stable solvent impregnated resins (SIR) containing 1,4-dihydroxyanthraquinone (quinizarin, QNZ) was proposed using Amberlite XAD-16 beads. The SIR was applied for the separation of Cd(II), Cu(II), Ni(II), and Zn(II) in aqueous media prior to the determination by flame atomic absorption spectrometry (FAAS). The optimum conditions for batch mode extraction of the above metal ions were investigated and it was found that the sorption of these metal ions from a 1000-ml aliquots of the solution on 1.5 g of the SIR can be carried out quantitatively at pH of 9.5 and an ionic strength of 0.01 mol dm^-3. The sorbed metal ions were subsequently eluted with 10 ml 2 mol dm^-3 HCl and the eluent was subjected to FAAS. Beer’s law was obeyed in the range of 910^-9 -110^-7 mol dm^-3 for Cd(II) and Zn(II), and 910^-8 -110^-6 mol dm^-3 for Cu(II) and Ni(II) contents. Significant interference was not observed due to the various ions, which could be found in natural water samples. The practical applicability of the method was confirmed using a synthetic certificated reference material (CRM) and spiked natural water samples.

Keywords: Solvent Impregnated Resins, Quinizarin, Amberlite, XAD-16, Faas, Dye 1,4-Dihydroxyanthraquinone Quinizarin, Liquid-Liquid-Extraction, Solid-Phase Extraction, Environmental-Samples, Spectrophotometric Determination, Amberlite XAD-16, Chelating Resins, Phosphoric-Acid, Divalent Metals, Heavy-Metals

? Jiménez-Núñez, M.L., Olguín, M.T. and Solache-Ríos, M. (2007), Fluoride removal from aqueous solutions by magnesium, nickel, and cobalt calcined hydrotalcite-like compounds. Separation Science and Technology, 42 (16), 3623-3639.

Full Text: 2007\Sep Sci Tec42, 3623.pdf

Abstract: Magnesium, nickel and cobalt hydrotalcite-like compounds (MgHT, NiHT, and CoHT), with similar M²⁺:Al³⁺ ratios were synthesized and characterized by XRD. It was confirmed from XRD that the materials have hydrotalcite-like structure. MgHT, NiHT, and CoHT were calcined and treated with fluoride solutions in a batch system. F^- ions were determined in the remaining solutions using a fluoride ion selective electrode. The kinetics of the fluoride ions sorption on calcined hydrotalcite-like compounds (CHT) was best described by the pseudo-second order model and the equilibrium was reached in less than 300 minutes in all cases (MgCHT, NiCHT, and CoCHT). The sorption isotherms of the fluoride by hydrotalcite like compounds can be explained by the Langmuir-Freundlich model and, the highest fluoride sorption capacity was obtained for NiCHT (1.202 mgF/gCHT). The fluoride removal from aqueous solutions by calcined hydrotalcite-like compounds depends on the adsorption properties of the thermal decomposition products and the regeneration reaction mechanism of the hydrotalcite-like compounds.

Keywords: Activated Alumina, Adsorption, Al Hydrotalcite, Aqueous Solutions, Catalytic-Properties, Cobalt, Drinking-Water, Equilibrium, Fluoride, Hydrotalcite, Hydrotalcites, Isotherms, Kinetics, Layered Double Hydroxides, Mechanism, Mixed Oxides, Ni-Al, Nickel, Pseudo-Second Order, Removal, Sorption, Sorption

? Gad, H.M.H. and Awwad, N.S. (2007), Factors affecting on the sorption/desorption of Eu(III) using activated carbon. Separation Science and Technology, 42 (16), 3657-3680.

Full Text: 2007\Sep Sci Tec42, 3657.pdf

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.

Keywords: Activated Carbon, Apricot Stone, Eu(III), Sorption/Desorption, Diverse Ions, Desorbing Agents, Aqueous-Solution, Adsorption, Ions, Removal, Water, Sorption, Surface, Equilibrium, Adsorbents, Sawdust

? Das, C., Das Gupta, S. and De, S. (2008), Simultaneous separation of mixture of metal ions and aromatic alcohol using cross flow micellar-enhanced ultrafiltration and recovery of surfactant. Separation Science and Technology, 43 (1), 71-92.

Full Text: 2008\Sep Sci Tec43, 71.pdf

Abstract: Separation characteristics of two systems of binary mixtures, namely, (i) copper and calcium, (II) copper and beta naphthol were studied using micellar-enhanced ultrafiltration (MEUF). Sodium dodecyl sulfate (SDS) was taken as the anionic surfactant. An organic polyamide membrane of molecular weight cut-off 5 kDa was used in cross flow MEUF experiments. Suitable feed surfactant concentration was found to be about 25 kg/m³. The effects of the feed composition, the transmembrane pressure drop, and the cross flow rate on the permeate flux and observed retention of each solute were studied. For single solute systems, the observed retention of both copper and calcium were about 99% for a solute concentration up to 1.0 kg/m³ but the retention reduced to 90% to 92% when solute concentration was increased to about 3 to 4 kg/m³. Retention of copper and calcium was in the range of 88 to 97% for various compositions in their binary mixture. Retention of beta naphthol was in between 82 to 84% in its mixture with copper, whereas, about 92% separation of beta naphthol was achieved in the single solute system. Binding isotherms of both calcium and copper and beta naphthol and copper were evaluated in their binary mixture using extended Langmuir isotherm. A two-step chemical treatment was adopted to recover the surfactant.

Keywords: Metal Ions, Aromatic Alcohol, Anionic Surfactant, Micellar-Enhanced, Ultrafiltration, Permeate Flux, Observed Retention, Precipitation, Aqueous Streams, Waste-Water, Simultaneous Removal, Dissolved Organics, Heavy-Metal, Phenol, Adsorption, Effluents, Nickel, Copper

? Gerçel, Ö. (2008), Biosorption of a basic dye from aqueous solutions by Euphorbia rigida. Separation Science and Technology, 43 (1), 192-211.

Full Text: 2008\Sep Sci Tec43, 192.pdf

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 G°, H° and S° 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.

Keywords: Adsorbents, Aqueous Solutions, Bagasse-Fly-Ash, Basic Dye, Biomass, Biosorbent, Biosorption, Biosorption Kinetics, Bottom Ash, De-Oiled-Soya, Dye, Equilibrium, Equilibrium Isotherm, Isotherm, Isotherm Models, Isotherms, Kinetic, Kinetics, Kinetics, Langmuir, Methylene-Blue Adsorption, Peanut Hull, pH, Removal, Size, Thermodynamic Parameters, Waste-Water

? Sun, Y., Li, A.M., Zhang, Q.X., Chen, J.L., Fu, D.F. and Wang, S.H. (2008), Adsorptive separation of tannic acid from aqueous solution by polymeric resins. Separation Science and Technology, 43 (2), 389-402.

Full Text: 2008\Sep Sci Tec43, 389.pdf

Abstract: An aminated hypercrosslinked polymeric resin AH-1, a macroporous polymeric resin NG-8 and its aminated derivative NG-9 were used for the adsorption of tannic acid from aqueous solution. The batch system was applied to study the adsorption equilibrium on the three polymeric adsorbents. Equilibrium adsorption data were obtained and fitted very well to Langmuir model. The results showed that the pore size distribution and the tertiary amino group on the polymer played a significant role in tannic acid adsorption performance, and polymer NG-9 showed the highest adsorption capacity due to the suitable pore size distribution and the presence of the tertiary amino group. In addition, a thermodynamic study was carried out to interpret the adsorption mechanism. The kinetic study testified that the tertiary amino group on the polymer matrix could decrease the adsorption rate and the large average pore size of the resin was in favor of the adsorption rate increase.

Keywords: Macroporous Polymer, Tannic Acid, Adsorption, Thermodynamics, Kinetics, Phenolic-Compounds, Adsorbent, Single

? Atia, A.A., Donia, A.M. and El-Hawary, M.M. (2008), Effect of crosslinker type and embedded magnetite on the uptake behavior of amine containing glycidyl methacrylate resins towards iron(III). Separation Science and Technology, 43 (2), 403-419.

Full Text: 2008\Sep Sci Tec43, 403.pdf

Abstract: Copolymerization of glycidyl methacrylate (GMA) in the presence of divinylbenzene (DVB) or N,N’-methylene bis-acrylamide (MBA) as hydrophobic or hydrophilic crosslinker was carried out. The obtained resins were immobilized with tetraethylenepentamine as active moieties. The (MBA) containing resin showed higher uptake capacity (9.0 mmol/g) towards Fe(III) compared to (DVB) containing one (8.1 mmol/g). Moreover, magnetization of (GMA/MBA) resin by embedded Fe₃O₄ dramatically improved its uptake towards Fe(III) to reach 13.0 mmol/g at 28°C-. Kinetic studies indicated that the adsorption of Fe(III) by the investigated resins follows the pseudo second order kinetics. The higher efficiency of the magnetic resin towards uptake of Fe(III) was also confirmed through column studies. Regeneration of the resins was achieved using acidified thiourea with HNO₃. The durability of the resins was checked up to 5 cycles with no appreciable change in uptake capacity or durability.

Keywords: Adsorption, Aqueous-Solutions, Chelating Resin, Copolymer, Copper(II), Glycidyl Methacrylate, Heavy-Metals, Hg(II), Immobilized, Ion-Exchange Properties, Iron, Iron, Kinetics, Particles, Removal, Resins, Thermodynamics

? Fiol, M., Escudero, C. and Villaescusa, I. (2008), Re-use of exhausted ground coffee waste for Cr(VI) sorption. Separation Science and Technology, 43 (3), 582-596.

Full Text: 2008\Sep Sci Tec43, 582.pdf

Abstract: Exhausted ground coffee waste has been investigated as metal biosorbent for Cr(VI) from aqueous solution. Maximum metal sorption was found to occur at initial pH 3.0. Kinetic studies revealed that the initial uptake was quite rapid, nevertheless, it took five days to reach equilibrium. The value of the Langmuir maximum uptake was found to be 10.2 mg Cr(VI)/g waste. The sorbent is able to reduce hexavalent chromium to its trivalent form. A solution of I M NaOH was the most effective desorption agent and after 24 hours contact 42% of total chromium was desorbed in both hexavalent and trivalent oxidation states.

Keywords: Metal Removal, Chromium, Low Cost Sorbent, Sorption, Aqueous-Solutions, Hexavalent Chromium, Removal, Adsorption, Ions, Adsorbent, Metals

? Monji, A.B., Ahmadi, S.J. and Zolfonoun, E. (2008), Selective biosorption of zirconium and hafnium from acidic aqueous solutions by rice bran, wheat bran and platanus orientalis tree leaves. Separation Science and Technology, 43 (3), 597-608.

Full Text: 2008\Sep Sci Tec43, 597.pdf

Abstract: The Zr(IV) and Hf(IV) biosorption characteristics of rice bran, wheat bran and Platanus orientalis tree leaves were examined as a function of initial pH, contact time, temperature, and initial metal ions concentration. Adsorption equilibriums were achieved in about 1, 5 and 40 min for rice bran, wheat bran, and leaves respectively. The biosorption behavior of leaves was significantly affected by solution pH whereas rice bran and wheat bran adsorption efficiencies were slightly affected by solution pH. The Freundlich and Langmuir adsorption equations, which are commonly used to describe sorption equilibrium for metals removal by biomasses, were use to represent the experimental and equilibrium data fitted well to the Langmuir isotherm model. The negative Gibbs free energy values obtained in this study with rice bran wheat bran and Platanus orientalis tree leaves confirmed the feasibility of the process and the spontaneous nature of sorption. In the optimum conditions, the adsorption efficiencies of other metal ions such as Fe³⁺, Cu²⁺, Pb²⁺, Hg²⁺, La³⁺, Ce³⁺ were significantly lower than Zr(IV) and Hf(IV) ions and these biomasses are excellent sorbents for the selective uptake of proposed ions from acidic aqueous solutions.

Keywords: Biosorption, Zirconium, Hafnium, Rice Bran, Wheat Bran, Platanus Orientalis Tree Leaves, Surfactant-Modified Montmorillonite, Heavy-Metals, Adsorption, Ions, Equilibrium, Sorption, Removal, Isotherm, Cadmium, Algae

? Bhatnagar, A., Ji, M., Choi, Y.H., Jung, W., Lee, S.H., Kim, S.J., Lee, G., Suk, H., Kim, H.S., Min, B., Kim, S.H., Jeon, B.H. and Kang, J.W. (2008), Removal of nitrate from water by adsorption onto zinc chloride treated activated carbon. Separation Science and Technology, 43 (4), 886-907.

Full Text: 2008\Sep Sci Tec43, 886.pdf

Abstract: Adsorption study with untreated and zinc chloride (ZnCl₂) treated coconut granular activated carbon (GAC) for nitrate removal from water has been carried out. Untreated coconut GAC was treated with ZnCl₂ and carbonized. The optimal conditions were selected by studying the influence of process variables such as chemical ratio and activation temperature. Experimental results reveal that chemical weight ratio of 200% and temperature of 500°C was found to be optimum for the maximum removal of nitrate from water. Both untreated and ZnCl₂ treated coconut GACs were characterized by scanning electron microscopy (SEM), Brunauer Emmett Teller (BET) N₂-gas adsorption, surface area and Energy Dispersive X-Ray (EDX) analysis. The comparison between untreated and ZnCl₂ treated GAC indicates that treatment with ZnCl₂ has significantly improved the adsorption efficacy of untreated GAC. The adsorption capacity of untreated and ZnCl₂ treated coconut GACs were found 1.7 and 10.2 mg/g, respectively. The adsorption of nitrate on ZnCl₂ treated coconut GAC was studied as a function of contact time, initial concentration of nitrate anion, temperature, and pH by batch mode adsorption experiments. The kinetic study reveals that equilibrium was achieved within one hour. The adsorption data conform best fit to the Langmuir isotherm. Kinetic study results reveal that present adsorption system followed a pseudo-second-order kinetics with pore-diffusion-controlled. Results of the present study recommend that the adsorption process using ZnCl₂ treated coconut GAC might be a promising innovative technology in future for nitrates removal from drinking water.

Keywords: Activated Carbon, Activation, Adsorption, Adsorption Isotherms, Analysis, Aqueous-Solutions, Bed Reactor, Bet, Capacity, Carbon, Chloride, Comparison, Denitrification, Drinking Water, Drinking-Water, EDX, Efficacy, Electron Microscopy, Equilibrium, Experiments, Function, Granular Activated Carbon, Isotherm, Kinetic, Kinetic Modeling, Kinetic Study, Kinetics, Langmuir, Langmuir Isotherm, Low-Cost Adsorbent, Nitrate Removal, pH, Pseudo-Second-Order Kinetics, Reduction, Removal, Scanning Electron Microscopy, SEM, Sorption, Surface Area, Technology, Temperature, Treatment, Waste-Water, Water, Water Treatment, Zero-Valent Iron, Zinc, ZnCl₂ Treated Activated Carbon

? Wang, X.S., He, L., Hu, H.Q. and Wang, J. (2008), Effect of temperature on the Pb(II) removal from single aqueous solutions by a locally natural mordenite: Equilibrium and kinetic modeling. Separation Science and Technology, 43 (4), 908-922.

Full Text: 2008\Sep Sci Tec43, 886.pdf

Abstract: Zeolites have been shown to be effective adsorbents for the removal of heavy metals from aqueous solutions. In this study, mordenite (a natural zeolite) has been used for the removal of lead ions to evaluate its potential use as a low-cost adsorbent. Batch experiments have been conducted to evaluate the equilibrium and process kinetics at different temperatures. The equilibrium experimental data for various temperatures studied conformed to the six adsorption isotherm equations: the Langnmir, Freundlich, Sips, Redlich-Peterson (RP), Dubinin-Radwhkevich (DR), and Flory-Huggins (FH). Constants were determined for each of the isotherms. The apparent thermodynamic parameters were calculated and the obtained values supported the conclusion that the lead ions adsorption onto mordenite was a spontaneous, exothermic process of physical nature. The kinetic experimental data fitted the pseudo-second-order, parabolic diffusion and Elovich equations successfully. The process of lead ions adsorption onto the Na-mordenite was diffusion-controlled. The value of apparent activation energy also confirmed a physical mechanism for the adsorption of lead ions onto Na-mordenite.

Keywords: Activation, Activation Energy, Adsorbent, Adsorbents, Adsorption, Adsorption Isotherm, Aqueous Solutions, Clinoptilolite, Copper, Diffusion, Equilibrium, Exchange, Experimental, Experiments, Freundlich, Heavy Metals, Isotherm, Isotherm Equations, Isotherms, Kinetic, Kinetic Modeling, Kinetics, Lead, Lead(II), Mechanism, Metals, Modeling, Mordenite, Na-Mordenite, Pb(II), Potential, Removal, Silica, Sorption, Temperature, Thermodynamic Parameters, Thermodynamics, Zeolite, Zeolites

? Ashrafizadeh, S.N., Khorasani, Z. and Gorjiara, M. (2008), Ammonia removal from aqueous solutions by Iranian natural zeolite. Separation Science and Technology, 43 (4), 960-978.

Full Text: 2008\Sep Sci Tec43, 960.pdf

Abstract: The capability of Iranian natural clinoptilolite for ammonia removal from aqueous solutions has been thoroughly studied. Both batch and continuous (column) experiments were carried out. The viability of this natural zeolite in reducing the leakage of ammonia to the environment through waste water streams was a main focus of this research. Through the batch experiments, the effect of process variables such as the size of zeolite particles, pH, and ammonia concentration of the feed solution on the kinetics of ammonia uptake were investigated. Ammonia removal occurred rapidly and within the first 15 minutes of contact time, a major part of ammonia was removed from the solution. An adsorption capacity about 17.8 mg NH₄⁺/g zeolite at feed ammonia concentration of 50 mg/L was obtained and the optimum range for pH was achieved about 5.5-7.6. The adsorption capacity of clinoptilolite in the continuous mode was about 15.16 and 15.36 mg NH₄⁺/g zeolite for the original and regenerated types of clinoptilolite, respectively, where feed ammonium concentration was 50 mg/L. Increasing the feed ammonium concentration to 100 mg/L did not reduce the capability of the column for its ammonium removal and up to a bed volume (BV) of 85, there was only less than 1 mg/L ammonium in the column outlet. Presence of cations such as Ca²⁺, Mg²⁺ and Na⁺ in the feed solution reduced the clinoptilolite adsorption capacity to about 11.68 mg NH₄⁺/g zeolite. Regeneration experiments were carried out using concentrated sodium chloride solutions, as well as tap water. Where tap water was used as the regenerant, gradual release of ammonium from exhausted clinoptilolite was observed.

Keywords: Ammonia, Clinoptilolite, Ion Exchange, Natural Zeolite, Wastewater, Fertilizer, Ion-Exchange, Waste-Water, Clinoptilolite, Mordenite

? Khambhaty, Y., Mody, K., Basha, S. and Jha, B. (2008), Hg(II) removal from aqueous solution by dead fungal biomass of marine Aspergillus niger: Kinetic studies. Separation Science and Technology,