Personal Research Database

Full Text: S\Sep Pur Tec24, 389.pdf

Abstract: Carbon prepared from peanut husks (PHC) has been used for the adsorption of Pb²⁺, Zn²⁺, Ni²⁺ and Cd²⁺, over a range of initial metal ion concentration (0.15 mM). Chemical and physical characteristics of PHC were determined. The effects of particle size and of carbon doses were evaluated by batch experiments. The kinetics of sorption were followed, based on the amounts of metal sorbed at various time intervals. The modeling of kinetic and isotherm curves has also been investigated. The rate constant and the reaction order have been calculated. The results show that Pb²⁺ has best affinity to PHC than Cd²⁺, Ni²⁺, Zn²⁺. From these results an order of the sorption capacity of metal ions sorbed was derived. (C) 2001 Elsevier Science BN. All rights reserved.

Keywords: Heavy Metals, Kinetic Adsorption, Peanut Husks, Characterization, Modeling, Blast-Furnace Sludge, Activated Carbon, Aqueous-Solution, Hull Carbon, Lead Ions, Cadmium, Sorption, Oxidation, Oxygen

Kadirvelu, K., Thamaraiselvi, K. and Namasivayam, C. (2001), Adsorption of nickel(II) from aqueous solution onto activated carbon prepared from coirpith. Separation and Purification Technology, 24 (3), 497-505.

Full Text: S\Sep Pur Tec24, 497.pdf

Abstract: Activated carbon has been prepared from coirpith by chemical activation and characterized. Carbonised coirpith is able to adsorb Ni(II) from aqueous solution. It was noted that a decreasing in the carbon concentration with constant Ni concentration, or an increase in the Ni concentration with constant carbon concentration resulted in a higher nickel uptake per unit weight of carbon. The Langmuir and Freundlich models for dynamics of metal ion uptake proposed in this work fit the experimental data reasonably well. The adsorption capacity (Q₀) calculated from Langmuir isotherm was 62.5 mg Ni(II) g^-1 at initial pH of 5.0 at 30 degreesC for the particle size 250-500 µm. The adsorption of Ni increased with pH from 2 to 7 and remained constant upto 10. The recovery of Ni(II) after adsorption can be carried out by treatment of the Ni loaded carbon with HCL Desorption studies confirms adsorption is ion exchange. As coirpith is discarded as waste material from coir processing industries, the carbon is expected to be economical product for metal ion remediation from water and wastewater. (C) 2001 Elsevier Science B.V. All rights reserved.

Keywords: Activated Carbon, Carbonization, Adsorption, Adsorption Isotherms, Heavy-Metal Ions, Waste-Water, By-Product, Agricultural Waste, Removal, Adsorbent, Sorption, Hulls

Monser, L. and Adhoum, N. (2002), Modified activated carbon for the removal of copper, zinc, chromium and cyanide from wastewater. Separation and Purification Technology, 26 (2-3), 137-146.

Full Text: S\Sep Pur Tec26, 137.pdf

Abstract: Modified activated carbon are carbonaceous adsorbents which have tetrabutyl ammonium iodide (TBAI) and sodium diethyl dithiocarbamate (SDDC) immobilised at their surface, This study investigates the adsorption of toxic ions, copper, zinc, chromium and cyanide on these adsorbents that have undergone surface modification with tetrabutyl ammonium (TBA) and SDDC in wastewater applications. The modification technique enhance the removal capacity of carbon and therefore decreases cost-effective removal of Cu(II), Zn(II), Cr(VI) and CN^- from metal finishing (electroplating unit) wastewater. Two separate fixed bed modified activated carbon columns were used, TBA-carbon column for cyanide removal and SDDC-carbon column for multi-species metal ions (Cu, Zn, Cr) removal. Wastewater from electroplating unit containing 37 mg l^-1 Cu, 27 mg l^-1 Zn, 9.5 mg l^-1 Cr and 40 mg l^-1 CN^- was treated through the modified columns. A total CN- removal was achieved when using the TBA-carbon column with a removal capacity of 29.2 mg g^-1 carbon. The TBA-carbon adsorbent was found to have an effective removal capacity of approximately five times that of plain carbon. Using SDDC-carbon column, Cu, Zn and Cr metal ions were eliminated with a removal capacity of 38, 9.9 and 6.84 mg g^-1, respectively. The SDDC-carbon column has an effective removal capacity for Cu (four times), Zn (four times) and Cr (two times) greater than plain carbon. (C) 2002 Elsevier Science B.V. All rights reserved.

Keywords: Activated Carbon, Modification, Fixed Bed Columns, Metal Finishing Wastewater, Aqueous-Solution, Adsorption, Lead, Fish

Çengeloğlu, Y., Kir, E. and Ersöz, M. (2002), Removal of fluoride from aqueous solution by using red mud. Separation and Purification Technology, 28 (1), 81-86.

Full Text: S\Sep Pur Tec28, 81.pdf

Abstract: The removal of fluoride from aqueous solution by using the original and activated red mud forms was studied in batch equilibration technique. Influence of pH. adsorbent dose and contact time on the adsorption were investigated. The fluoride adsorption capacity of activated form was found to be higher than that of the original form. The maximum removal of fluoride ion was obtained at pH 5.5. The removal of fluoride was expressed with Langmuir and Freundlich isotherms. Langmuir adsorption isotherm Curve was found to be significant. It was found that the sufficient time for adsorption equilibrium of fluoride ions is 2 h. The possibility of removal of fluoride ion by using red mud is explained on the basis of the chemical nature and specific interaction with metal oxide surfaces and the results are interpreted in terms of pH variations. (C) 2002 Elsevier Science B.V. All rights reserved.

Keywords: Red Mud, Adsorption, Removal of Fluoride, Utilization, Donnan Dialysis, Ion-Exchange, Adsorption, Waters

Abusafa, A. and Yücel, H. (2002), Removal of ¹³⁷Cs from aqueous solutions using different cationic forms of a natural zeolite: Clinoptilolite. Separation and Purification Technology, 28 (2), 103-116.

Full Text: S\Sep Pur Tec28, 103.pdf

Abstract: Distribution coefficients of cesium on natural and cation-enriched (Na⁺, K⁺, NH₄⁺ and Ca⁺²) forms of clinoptilolite were measured by batch, radioactive tracer technique. The measurements were carried out for an initial cesium concentration range of 10^-6-10^-1 mol/dm³ and at temperatures of 25, 40, 60 and 80 degreesC. Experimental isotherms evaluated from distribution coefficients were fit to Langmuir, Freundlich and Dubinin-Radushkevich (D-R)models. of the models tested, D-R model was found to represent the isotherms better in a wider range of concentrations than either Langmuir or Freundlich model. Breakthrough behavior of cesium on natural and cation-enriched forms of clinoptilolite for a particular set of conditions were also determined in a small size column. Column parameters were evaluated using mass transfer zone concept. (C) 2002 Elsevier Science B.V. All rights reserved.

Keywords: Clinoptilolite, Cesium, Sorption Isotherm, Dubinin-Radushkevich Isotherm, Adsorption, Exchange, Soil

? Matsumoto, M., Shimizu, T. and Kondo, K. (2002), Selective adsorption of glucose on novel chitosan gel modified by phenylboronate. Separation and Purification Technology, 29 (3), 229-233.

Full Text: 2002\Sep Pur Tec29, 229.pdf

Abstract: Novel gels from phenylboronate derivatives of chitosan were prepared for the adsorption of saccharides. Two chitosan gels were used: one modified by phenylboronate via Schiff’s base formation (A) and one in which phenylboronate was introduced by amide formation (B). The adsorption characteristics Of D-glucose and 1-methyl-alpha-D-glucoside on these gels were examined and compared with a commercial gel. Though both chitosan gels were inferior to the commercial gel in their adsorption capacity, the chitosan gel (A) showed a much higher selectivity of D-glucose to 1-methyl-alpha-D-glucoside in comparison to the commercial gel. (C) 2002 Elsevier Science B.V. All rights reserved.

Keywords: Adsorption, Adsorption Capacity, Boric-Acid, Capacity, Chitosan, Gel, Glucose, Modified, Resin, Saccharides, Selectivity

Métivier-Pignon, H., Faur-Brasquet, C. and Le Cloirec, P. (2003), Adsorption of dyes onto activated carbon cloths: approach of adsorption mechanisms and coupling of ACC with ultrafiltration to treat coloured wastewaters. Separation and Purification Technology, 31 (1), 3-11.

Full Text: S\Sep Pur Tec31, 3.pdf

Abstract: Recent absorbents, activated carbon cloths (ACCs) are used to absorb dyes. First, adsorption is carried out in batch reactors, initial kinetic coefficients and adsorption capacities are determined, thanks to adsorption kinetics and isotherms. Twenty-two dyes are tested and two ACCs are used, one exclusively microporous, the other being partially mesoporous. With the view to understanding the absorption process of dyes onto ACCs, quantitative structure–activity relationships are developed using molecular connectivity indices as dyes descriptions. The statistical tool introduced is the multiple linear regression. Then, the ability of ACC to treat coloured wastewater is assessed by coupling adsorption with ultrafiltration. First, both processes are operated step after step. The membrane filtration step (3000 Da molecular weight cut-off) allows a great removal of turbidity (>98%), whereas adsorption onto ACC provides the decolourization of the stream with an adsorption capacity in continuous flow reactor of 180 mg g^-1 of the acid orange 7. Secondly, ultrafiltration and adsorption onto ACC are operated continuously. When the breakthrough is reached, a total volume of 101 l is successfully discoloured, with a permeate flow rate higher than 20 l m^-2 h^-1.

Keywords: Adsorption, Activated Carbon Cloth, Dyes, Quantitative Structure–Activity Relationship, Ultrafiltration

Hu, Z.H., Lei, L., Li, Y.J. and Ni, Y.M. (2003), Chromium adsorption on high-performance activated carbons from aqueous solution. Separation and Purification Technology, 31 (1), 13-18.

Full Text: S\Sep Pur Tec31, 13.pdf

Abstract: The adsorption of Cr(VI) from aqueous solutions by commercial and lab-made high surface area (HSA)-activated carbons was investigated. Physiochemical factors such as equilibrium time, temperature and solution pH that affect the magnitude of Cr(VI) adsorption were studied. The HSA-activated carbons showed high performance for Cr removal, and their adsorption capacity is several times larger than that of commercial carbons. Both micropores and mesopores have important contribution on the adsorption. However, desorption is more dependent on the mesoporosity of activated carbons. Therefore, regeneration is easier for the carbon with high mesoporosity. As a result, the adsorption capacity of mesoporous carbon could be recovered over 97%, whereas 54% for highly microporous carbon.

Keywords: Activated Carbon, Chromium, Adsorption, Regeneration, Wastewater

? Orthman, J., Zhu, H.Y. and Lu, G.Q. (2003), Use of anion clay hydrotalcite to remove coloured organics from aqueous solutions. Separation and Purification Technology, 31 (1), 53-59.

Full Text: 2003\Sep Pur Tec31, 53.pdf

Abstract: Anion clay hydrotalcite sorbents were prepared to investigate their adsorption capabilities in the removal of coloured organic substances from various aqueous systems. Anion clay hydrotalcite was found to be particularly effective at removing negatively charged species. Its excellent uptake levels of anionic species can be accounted for by its high surface area and anion exchange ability. That is, coloured substances can be adsorbed on the surface or enter the interlayer region of the clay by anion exchange. In the adsorption of Acid Blue 29 on the anion clay hydrotalcite, an equilibrium time of 1 h with dye removal exceeding 99% was obtained. The hydrotalcite was found to have an adsorption capacity marginally below that of commercial activated carbon. It should be noted that the spent sorbents can be regenerated easily by heating at 723 K to remove all adsorbed organics. The reused sorbents displayed greater adsorption capabilities than the newly prepared hydrotalcite. Hence, the anion clay hydrotalcite is easily recoverable and reusable such that it is a promising sorbent for environmental and purification purposes.

Keywords: Anion Clay, Hydrotalcite, Ion Exchange, Coloured Organics, Environmental Purification, Regeneration

? Chakraborty, S., Purkait, M.K., DasGupta, S., De, S. and Basu, J.K. (2003), Nanofiltration of textile plant effluent for color removal and reduction in COD. Separation and Purification Technology, 31 (2), 141-151.

Full Text: 2003\Sep Pur Tec31, 141.pdf

Abstract: A membrane based separation process (nanofiltration, NF) is used to treat the effluent from a textile plant. The dye mixture contains reactive black dye (Cibacron Black B) and reactive red dye (Cibacron Red RB). An organic membrane with molecular weight cut-off of 400 is used for the experiments. The experiments are conducted in an unstirred batch and a rectangular cross flow cell. Separations with retentions up to 94 and 92% of the two dyes are achieved respectively in the cross flow cell where steady state is attained quickly. It is important to note that NF techniques achieve a sharp reduction in chemical oxygen demand (COD), (up to 94% in cross flow cell), as the dyes are removed from the permeate. A parametric study of the separation process is undertaken to characterize the effects of the operating variables, e.g., trans-membrane pressure, dye concentration in the feed and cross flow velocity in case of cross flow NF. (C) 2002 Elsevier Science B.V. All rights reserved.

Keywords: Nanofiltration, Cross Flow, Textile Effluent, Dye, Chemical Oxygen Demand, Flux Decline, Water, Dyes

? Malik, P.K. and Saha, S.K. (2003), Oxidation of direct dyes with hydrogen peroxide using ferrous ion as catalyst. Separation and Purification Technology, 31 (3), 241-250.

Full Text: 2003\Sep Pur Tec31, 241.pdf

Abstract: The oxidative degradation of two direct dyes, Blue 2B (B54) and Red 12B (R31) in aqueous solution has been studied using Fenton’s reagent (Fe²⁺ and H₂O₂). Results show that dyes are decomposed in a two-stage reaction. In the first stage. dyes are decomposed rapidly, and somewhat less rapidly in the second stage. The effects of different system variables like initial pH of the medium, initial concentrations of the dye, Fe²⁺ and H₂O₂, reaction temperature, and added Cl^- and SO₄^2- ions have been investigated. The degradation rate is strongly dependent on the initial concentrations of the dye, Fe²⁺ and H₂O₂. The results indicate that the B54 and R31 can be most effectively oxidised in an aqueous medium of pH 3 at an initial [Fe²⁺]:[H₂O₂]:[dye] ratio of 1:32.9:2.4 and 1:16.5:1.8 (mM), respectively. At the optimum initial ratio of [Fe²⁺]:[H₂O₂]:[dye], 97% degradation can be achieved in 30 min at a temperature of 30°C, and 70% removal of initial chemical oxygen demand (COD) is achieved after 60 min. The degradation of both the dyes obeys first order rate kinetics with respect to the concentration of the dye in the second stage of oxidation. The results will be useful in designing wastewater treatment plants. (C) 2002 Elsevier Science B.V. All rights reserved.

Keywords: Fenton’s Reagent, Direct Dye, Oxidation, Ferrous Ion, Hydrogen Peroxide, Wastewater, Fenton-Like Reaction, Waste-Water, Chemical Oxidation, Biological Treatment, Contaminated Soils, Aqueous-Solutions, Reagent, Degradation, Electrode

Al-Asheh, S., Banat, F. and Abu-Aitah, L. (2003), Adsorption of phenol using different types of activated bentonites. Separation and Purification Technology, 33 (1), 1-10.

Full Text: S\Sep Pur Tec28, 1.pdf

Abstract: Naturally occurring bentonite is able to adsorb phenol from aqueous solutions. Sodium-treated bentonite underwent several activation methods before its exposure to the phenol solution. It was treated with cetyltrimethyl ammonium bromide (CTAB) as a cationic surfactant, with aluminum-hydroxypolycation as a pillaring agent and a combination of the two (CATB/Al-Bentonite). The Na-bentonite was also physically treated in an oven operated at 850 °C. Batch adsorption tests were carried out to remove phenol from aqueous solution using the above-mentioned bentonites. It was found that the amount of phenol removal was seriated in the following order: CTAB/Al-Bentonite>Al-Bentonite>CTAB bentonite>thermal-treated bentonite>cyclohexane-treated bentonite>natural bentonite. X-ray diffraction analysis showed that an increase in the microscopic platelets of bentonite when treated with CTAB was the reason behind the highest uptake of phenol. The increase in sorbent concentration or initial pH values of the solutions resulted in more phenol removal from the solution. The increase in temperature decreased phenol uptake by the bentonites used in this work. The Freundlich isotherm model was employed and well represented the experimental data.

Keywords: Adsorption, Phenol, Bentonite, CTAB, Al-Bentonite, Thermal Bentonite, Freundlich Model

Li, Q.B., Wu, S.T., Liu, G., Liao, X.K., Deng, X., Sun, D.H., Hu, Y.L. and Huang, Y.L. (2004), Simultaneous biosorption of cadmium(II) and lead(II) ions by pretreated biomass of Phanerochaete chrysosporium. Separation and Purification Technology, 34 (1-3), 135-142.

Full Text: S\Sep Pur Tec34, 135.pdf

Abstract: The article extends the study on the treatment of heavy metal wastewater by considering the competitive biosorption of two metal ions together, Cd(II) and Pb(II), by Phanerochaete chrysosporium, a filamentous fungus, under optimum biosorption conditions determined for each metal ion. The effects of the presence of one metal ion on the biosorption of the other metal ion were investigated in terms of equilibrium isotherm and adsorption yield. Experimental results indicated that the uptake capacity and adsorption yield of one metal ion were reduced by the presence of the other metal ion. In addition, comparisons between biosorption of Pb(II) ions and Cd(II) ions by the biomass of P. chrysosporium in the binary solution could lead to the conclusion that biosorption of Pb(II) ions was preferential to that of Cd(II) ions. In the single-ion situation, biosorption of Cd(II) ions and Pb(II) ions had the optimum adsorption conditions in common, which were the solution pH 4.5, temperature 27 °C. The maximum uptake obtained at initial concentration of Cd(II) ions 50 mg l⁻¹, could reach 15.2 mg g⁻¹, for Pb(II) ions it could reach 12.34 mg g⁻¹. Both the adsorption equilibrium data fitted the Freundlich model well. Moreover, the uptake of Cd(II) ions had a less sensitive dependence on temperature than that of Pb(II) ions.

Keywords: Binary Ions Adsorption, Heavy Metals, Fine-Chemical, Wastewater, Fungus

Kandah, M.I. (2004), Zinc and cadmium adsorption on low-grade phosphate. Separation and Purification Technology, 35 (1), 61-70.

Full Text: S\Sep Pur Tec35, 61.pdf

Abstract: An attempt was made to utilize low-grade phosphate (LGP) as an adsorbent for Zn²⁺ and Cd²⁺ over a range of initial metal ions concentrations (10–50 ppm), agitation time (5–210 min), adsorbent concentration (1–7 g/l) and pH (2–6). Adsorption of both Zn²⁺ and Cd²⁺ increased with increased LGP concentration and reached maximum uptake at 5 g/l and pH between 4 and 6 for both metal ions. The amount adsorbed increases with time and initial metal concentrations for both metal ions. The equilibrium time was achieved for both metal ions after 30 min. The process of uptake obeys both the Langmuir and Freundlich isotherms. The affinity of LGP for H⁺ is considerably higher than for Zn²⁺ and Cd²⁺. The equilibrium uptake of zinc ions decreases with the increase in the initial cadmium ions concentration and that of cadmium ions decreases as the initial zinc ions concentration increases. Desorption of LGP with 0.1 N H₂SO₄ was done for three cycles successfully.

Keywords: Low-Grade Phosphate, Zinc, Cadmium, Adsorption

Aksu, Z. and Kabasakal, E. (2004), Batch adsorption of 2,4-dichlorophenoxy-acetic acid (2,4-D) from aqueous solution by granular activated carbon. Separation and Purification Technology, 35 (3), 223-240.

Full Text: S\Sep Pur Tec35, 223.pdf

Abstract: Adsorption equilibrium, kinetics and thermodynamics of 2,4-dichlorophenoxy-acetic acid (2,4-d), one of the most commonly used phenoxy acid herbicides, onto granular activated carbon were studied in aqueous solution in a batch system with respect to pH, temperature and initial 2,4-d concentration. At 600 mg l^-1 initial 2,4-d concentration activated carbon exhibited the highest 2,4-d uptake capacity of 518.0 mg g^-1 at 45 °C and at an initial pH value of 2.0. Freundlich, Langmuir, Redlich-Peterson and Koble-Corrigan isotherm models were applied to experimental equilibrium data of 2,4-d adsorption depending on temperature. Equilibrium data fitted very well to the Freundlich and Koble-Corrigan equilibrium models in the studied concentration range of 2,4-d at all the temperatures studied. Some simple mass transfer and kinetic models were applied to the experimental data to examine the mechanisms of adsorption and potential rate controlling steps such as external mass transfer, intraparticle diffusion and adsorption process. It was found that both the boundary layer and intraparticle diffusion played important roles in the adsorption mechanisms of 2,4-d, and adsorption kinetics followed a pseudo first-order kinetic model rather than pseudo second-order and saturation type kinetic models for all temperatures studied. The activation energy of adsorption (EA) was determined as 8.46 kJ mol^-1 using the Arrhenius equation. Using the thermodynamic equilibrium coefficients obtained at different temperatures, the thermodynamic constants of adsorption (G°, H° and S°) were also evaluated.

Keywords: Adsorption, 2,4-d, Granular Activated Carbon, Equilibrium, Kinetics, Thermodynamic, Batch System

Yildiz, E. (2004), Phosphate removal from water by fly ash using crossflow microfiltration. Separation and Purification Technology, 35 (3), 241-252.

Full Text: S\Sep Pur Tec35, 241.pdf

Abstract: Removal of phosphate ions (PO₄-P) from aqueous solution by means of fly ash was investigated in a crossflow microfiltration system. Batch experiments prior to membrane filtration were conducted to determine PO₄-P removal capacity of the fly ash. The effect of PO₄-P concentration, initial pH of solution and the fly ash dosage on the PO₄-P removal was studied. It was found that if the initial pH of solution is about 6, maximum PO₄-P removal is obtained and as the fly ash dosage increase the percentage of PO₄-P removal rises due to an increase in solubility of calcium ions and final pH in water. In membrane filtration, PO₄-P treated with the fly ash was separated from water with crossflow microfiltration technique. The effect of the fly ash dosage, PO₄-P concentration, transmembrane pressure drop (DeltaP) and membrane type on the membrane fluxes (J*) and PO₄-P rejections (R-p*) were investigated. Under certain conditions, 100% R* could be achieved depending on the fly ash dosage. It was seen that J* and R* increase with increasing of the dosage. When the concentration Of PO₄-P in the feed solution is increased, R* reduces because of the low final pH and inadequate calcium ion concentration. Furthermore, it was also found that results obtained for J* and R* were better for cellulose nitrate (CN) membranes compared with cellulose acetate (CA) membranes. The effect of transmembrane pressure drop (DeltaP), the fly ash dosage and PO₄-P concentration on steady state permeate fluxes and rejections have been explained by specific cake resistances (alpha). It has been seen that separation of insoluble PO₄-P compounds by crossflow membrane filtration seems to be advantageous to classical batch separation in respect of efficiency. (C) 2003 Elsevier B.V. All rights reserved.

Keywords: Crossflow Filtration, Microfiltration, Phosphate Removal, Fly Ash, Flux Decline, Aqueous-Solutions, Heavy-Metals, Waste-Water, Filtration, Adsorption, Bagasse

Inan, H., Dimoglo, A., Şimşek, H. and Karpuzcu, A. (2004), Olive oil mill wastewater treatment by means of electro-coagulation. Separation and Purification Technology,