Personal Research Database

Full Text: S\Sep Sci Tec36, 3191.pdf

Abstract: Activated carbons with different porous structures have been prepared from Pinus caribaea sawdust through the Use of CO₂ and steam as activating agents. The evolution of the Brunauer- Emmett-Teller (BET) surface area upon activation becomes fairly similar in both cases, and values above 1000 m², g can be reached at high burn-off levels. Activation with steam produces a more developed porous structure, with a substantially higher contribution of mesoporosity, than does activation with CO₂. Increasing the activation temperature leads in both cases to a wide pore-size distribution. The presence of a well-developed mesoporosity makes the resulting products good candidates for adsorbents for water and wastewater treatment. For these purposes, the characteristics of these activated carbons are comparable to those used as commercial adsorbents in those fields, showing in the case of the steam-activated carbons, a somewhat higher mesopore volume than many of the commercial products while maintaining similar surface area values to them. The relative simplicity of the process makes the production of steam-activated carbons a feasible and economically valuable alternative for sawmill wastes

Keywords: Activated Carbon, Activated Carbons, Adsorbents, Adsorption, Agent, Chemical Activation, CO₂, H₂O, Kraft Lignin, Pore Size Distribution, Porosity, Porous Structure, Sawdust, Sawdust Waste, Steam, Surface Area, Wastewater, ZnCl₂

Mcafee, B.J., Gould, W.D., Nadeau, J.C. and da Costa, A.C.A. (2001), Biosorption of metal ions using chitosan, chitin, and biomass of Rhizopus oryzae. Separation Science and Technology, 36 (14), 3207-3222.

Full Text: S\Sep Sci Tec36, 3207.pdf

Abstract: The biosorptive capacity of dried biomass fungus Rhizopus oryzae Went & Prinsen-Geerlings for metal sorption was compared with commercially available sources of chitin, chitosan and chitosan cross-linked with benzoquinone. Initial pH of the metal solution significantly influenced metal uptake capacity. The optimum biomass/solution ratio for metal uptake in all systems was 1 g/L. The highest metal uptake values (137, 108, 58, and 124 mg/g, respectively, for copper, zinc, arsenic, and chromium) were achieved with chitosan (1 g/L, at pH 4) from initial metal concentrations of 400 mg/L. Decreases in mean metal concentrations from a simulated copper/zinc mine effluent were 73%, 14%, and 36% for copper, aluminum, and zinc, respectively, which corresponded to respective metal uptake values of 16, 11, and 21 mg/g. Sorption from a simulated gold mine effluent showed decreases in mean concentrations of aluminum, arsenic, and copper of 85%, 30%, and 92%, respectively, which corresponded to respective metal uptake values of 3.0, 6.0, and 1.6 mg/g. The observed decreases in copper levels to concentrations below 1 mg/L indicate potential for specific polishing applications. At low pH, R oryzae biomass was more resistant than was chitosan. Cross-linking with benzoquinone under alkaline conditions conferred stability to the chitosan biomass under low pH, but some reduction in sorption capacity was observed.

Keywords: Biosorption, Chitosan, Copper, Zinc, Chromium, Rhizopus, Hexavalent Chromium, Uranium Biosorption, Fungal Biomass, Heavy-Metals, R-arrhizus, Removal, Copper, Adsorption, Mechanism, Seaweed

Stefanova, R.Y. (2001), Metal ion removal by modified polyacrylonitrile sorbent preliminarily converted into an inner salt. Separation Science and Technology, 36 (15), 3411-3426.

Full Text: S\Sep Sci Tec36, 3411.pdf

Abstract: Metal ion removal from acidic solutions with a high electrolyte concentration was completed through a modified polyacrylonitrile sorbent. The effects of the initial ion concentration, pH, the ionic strength, and anionic influence on the sorption behavior of the modified polymer were investigated. The distribution coefficient values for metal ions of various initial concentrations at 0.1 mol/L ionic strength increased in the following order: Mg²⁺ < Co²⁺ < Ni²⁺ < Zn²⁺ + Cd²⁺ < Cu²⁺ < Pb²⁺. The change of the ionic strength of the solution exerts a slight influence on the removal of copper, lead, and cadmium ions from aqueous solutions. Competition sorption studies were conducted at pH 4, ionic strength 0.5 mol/L, and with competing metal ions added at equivalent initial concentrations in the 2-component systems. Complete elution of metal ions from a loaded modified polymer was achieved with a nitric acid solution (pH 1.0–1.5) or by a subsequent treatment with 3% NH₄OH solution. The modified polymer has a high selectivity toward lead and copper ions and could be used to remove and separate different amounts of these elements from metal-bearing solutions and industrial wastewater with a high electrolyte concentration.

Büyüktuncel, E., Tuncel, A., Genç, Ö. and Denizli, A. (2001), Selective removal of lead ions by polyethylene glycol methacrylate gel beads carrying Cibacron Blue F3GA. Separation Science and Technology, 36 (15), 3427-3438.

Full Text: S\Sep Sci Tec36, 3427.pdf

Abstract: Polyethylene glycol methacrylate (PEG-MA) gel beads carrying Cibacron Blue F3GA (42.6 μmol/g polymer) were prepared for the removal of Pb(II), Cu(II), and Cd(II) from aqueous solutions that contained different amounts of these ions (10–100 mg/L) and at different pH values (2.0–7.0). Adsorption rates were high, and adsorption equilibria were reached within 20 minutes. Adsorption of these metal ions on the unmodified PEG-MA gel beads was zero. The maximum adsorptions of heavy metal ions onto the Cibacron Blue F3GA–attached microbeads from single solutions were 23.3 mg/g (112.4 μmol/g) for Pb(II), 12.4 mg/g (110.3 μmol/g) for Cd(II), and 7.0 mg/g (110.2 μmol/g) for Cu(II). When the heavy metal ions competed (in the case of the adsorption from their mixture) the amounts of adsorption were 14.96 mg/g (72.2 μmol/g) for Pb(II), 0.72 mg/g (11.3 μmol/g) for Cu(II), and 1.10 mg/g (9.8 μmol/g) for Cd(II). Under competitive conditions, the system showed high selectivity for Pb(II) ions. The formation constants of Cibacron Blue F3GA–metal ion complexes were investigated through the application of the Ružić method. The calculated values of formation constants were 8.5×10⁵ L/mol¹ for Pb(II) dye, 2.5×10⁵ L/mol for Cu(II) dye, and 8.2×10⁴ L/mol for the Cd(II) dye complex. PEG-MA gel beads carrying Cibacron Blue F3GA can be regenerated through washing with a solution of nitric acid (0.1 mol/L). The maximum regeneration value was as high as 98.5%. These PEG-MA gel beads are suitable for more than 3 adsorption-desorption cycles without experiencing considerable loss of adsorption capacity.

Chen, J.P. and Wang, L. (2001), Characterization of a Ca-alginate based ion-exchange resin and its applications in lead, copper, and zinc removal. Separation Science and Technology, 36 (16), 3617-3637.

Full Text: S\Sep Sci Tec36, 3617.pdf

Abstract: Characterization of a novel ca-alginate based ion-exchange resin and its application in metal removal were investigated. The metal removal percentages increased from almost 0 to nearly 100% for metal concentrations < 0.1 mmol/L at pH 1.2 to 4, and a plateau was established at pH > 4. The removal percentages were in the following order: Pb²⁺ > Cu²⁺ > Zn²⁺ at pH < 4. Lower initial concentrations and ionic strengths slightly enhanced the removal percentage. The maximum metal removal capacities (q_max) were 2.01 and 2.04 mmol/g for lead and copper, respectively, which are much higher than activated carbons and other reported biosorbents. Competitive effects were important for zinc removal, but less significant for lead and copper uptake. Organic chemical leaching from the resin was negligible.

The single- and multiple-species metal ions were removed completely within approximately 90 and 130 minutes, respectively. The lead removal became much faster when its concentration was decreased and in the absence of other metal ions. Presence of competitive metal ions significantly reduced the metal uptake rate. Removal process kinetics were controlled by the mass transfer, while the local equilibrium followed an ion-exchange relationship.

Keywords: Ca-Alginate Based Ion-Exchange Resin, Metal Removal, Equilibrium, Kinetics, Competitive Effect, Aqueous-Solutions, Calcium Alginate, Activated Carbon, Marine-Algae, Metal-Ions, Z-Ramigera, Biosorption, Adsorption, Biomass, Recovery

Karabulut, S., Karabakan, A., Denizli, A. and Yurum, Y. (2001), Cadmium(II) and mercury(II) removal from aquatic solutions with low-rank Turkish coal. Separation Science and Technology, 36 (16), 3657-3671.

Full Text: S\Sep Sci Tec36, 3657.pdf

Abstract: Removal of heavy metal ions from aqueous solutions containing low-to-moderate levels of contamination using Turkish Beypazari low-rank coal was investigated. Carboxylic acid and phenolic hydroxyl functional groups on the coal surface were the adsorption sites for heavy metal ions via the ion-exchange mechanism. The equilibrium pH of the coal-solution mixture was the principal factor controlling the extent of removal of Cd(II) and Hg(II) from aqueous solutions. The optimum pH was 4.0, and the adsorption reached equilibrium in 30 minutes. The maximum adsorption capacities of the metal ions from their single solutions were 1.55 mg for Hg(II) and 1.42 mg for Cd(II) per g of coal. Based on a weight uptake by coal, Hg(II) was found to have a greater affinity for the adsorption sites than does Cd(II). The same behavior was observed during competitive adsorption, that is, adsorption from binary solutions. The adsorption phenomena followed a typical Langmuir isotherm. The maximum adsorption capacities (q_m) were calculated as 2.03 mg/g and 1.70 mg/g for Hg(II) and Cd(II), respectively. The K-d values were 8.2 mg/L for Cd(II) and 9.8 mg/L for Hg(II). The use of low-rank coal was considerably effective in removing Hg(II) and Cd(II) from aqueous solutions. High amounts of adsorbed metal ions could be desorbed (up to 90%) with 25 mmol/L EDTA. Low-rank Turkish coals are suitable for use in more than 10 cycles without experiencing significant loss of adsorption capacity.

Keywords: Turkish Low-Rank Coal, Heavy Metal Ions, Adsorption, Metal Removal, Metal-Ions, Aqueous-Solution, Amidoxime Groups, Adsorption, Sorption, Recovery, Copper, Water, Preconcentration, Separation

Leyva-Ramos, R., Bernal-Jacome, L.A., Guerrero-Coronado, R.M. and Fuentes-Rubio, L. (2001), Competitive adsorption of Cd(II) and Zn(II) from aqueous solution onto activated carbon. Separation Science and Technology, 36 (16), 3673-3687.

Full Text: S\Sep Sci Tec36, 3673.pdf

Abstract: Single and simultaneous Cd(II) and Zn(II) adsorption isotherms from aqueous solution onto activated carbon were determined experimentally. Single isotherms for these ions fit the Langmuir isotherm well, and the maximum molar uptake of Zn(II) aver-aged 1.6 times that of Cd(II). The simultaneous adsorption isotherms also fit the bisolute Langmuir isotherm modified with an interaction factor. Adsorption of each single ion was reduced by the presence of the other ion, which competed for some of the same active sites. The Zn(II) isotherm proved to be more sensitive to the presence of the competing ion than did the Cd(II) isotherm.

Keywords: Activated Carbon, Cadmium, Competitive Adsorption, Single Adsorption, Zinc, Cd, Biosorption, Sorption, Single, Zn, Langmuir, Cadmium, Copper, Metal, Cu

Lu, Y.J., Wang, Y.S. and Zhu, X.H. (2001), The removal of bromophenol blue from water by solvent sublation. Separation Science and Technology, 36 (16), 3763-3776.

Full Text: S\Sep Sci Tec36, 3763.pdf

Abstract: Bromophenol blue (BB), an anionic dye, was removed from aqueous solution by solvent sublation of a BB hexadecyl-pyridium-chloride (HPC) complex (sublate) into isopentanol. A stoichiometric amount of surfactant (surfactant-dye = 2: 1) was the most effective compound for the removal, with over 95% BB removed from the aqueous solution in 10 minutes by solvent sublation. The removal rate was somewhat enhanced by high airflow rates and was also more or less independent of the organic solvent volume floated on the top of the aqueous column. The effects of electrolytes (e.g. KCl), nonhydrophobic organic compounds (e.g. ethanol), and pH of the solution upon the process were studied. The infrared spectra showed that the interaction between sublate and organic solvent was weak. The comparison of air stripping and solvent extraction with the solvent-sublation process was made. The solvent-sublation process was consistent with first order kinetics. A characteristic parameter, apparent activation energy of attachment of the sublate to bubbles, was determined as 4.77 KJ/mol.

Keywords: Adsorbing Colloid Flotation, Volatile Organic-Compounds, Trace-Element Separation, Refractory Organics, Transport Extraction, Aeration, Preconcentration, Atmosphere, Kinetics, Emission

Matis, K.A. and Zouboulis, A.I. (2001), Flotation techniques in water technology for metals recovery: The impact of speciation. Separation Science and Technology, 36 (16), 3777-3800.

Full Text: S\Sep Sci Tec36, 3777.pdf

Abstract: Toxic metals exist in the effluents of many industrial operations. The impact of chemical speciation was stressed during various flotation applications for metal separation from the effluent. Examples of recent investigations include the removal of arsenic ions by iron oxides, speciation studies of chromium ions, the selective separation of molybdate anions (and verification of extant phosphate, arsenate, and silicate impurities), the recovery of tungstates, the biosorption of metals (i.e., the selective removal of copper), the use of pyrite and other solid wastes as adsorbents, and the classical case of mixed sulfide mineral flotation (pyrite oxidation, use of surface complexation modeling, etc.). Thermodynamic equilibrium diagrams and software packages were employed to interpret the removal mechanism involved.

Saito, T. and Torii, S. (2002), Microcapsule for adsorption and recovery of cadmium(II) ion. Separation Science and Technology, 37 (1), 77-87.

Full Text: S\Sep Sci Tec37, 77.pdf

Abstract: A chelate resin that adsorbed bathocuproinedisulfonate ion on an anion exchange resin was synthesized, and then polystyrene microcapsules containing the chelate resin were prepared by interfacial polymerization with W/O/W emulsions. The adsorption behavior of metallic ions such as Cu²⁺, Cd²⁺, Co²⁺, Ni²⁺, and Zn²⁺ ions into the microcapsules obtained then was examined at 25degreesC. The adsorption rate of the Cd²⁺ ion to the microcapsules was over 9 times more than that of the Cu²⁺, Co²⁺, Ni²⁺, and Zn²⁺ ions. None of the metallic complexes trapped in the microcapsules were affected by the outside environment such as pH, and the Cd²⁺ ion remained unaffected in the microcapsules even in a highly acidic solution.

Keywords: Cadmium Ion, Microcapsule, Chelate Resin, Adsorbent, Bathocuproinedisulfonic Acid Disodium Salt

Titus, E., Kalkar, A.K. and Gaikar, V.G. (2002), Adsorption of anilines and cresols on NaX and different cation exchanged zeolites (equilibrium, kinetic, and IR investigations). Separation Science and Technology, 37 (1), 105-125.

Full Text: S\Sep Sci Tec37, 105.pdf

Abstract: The equilibrium isotherms and the rate of adsorption have been measured for anilines and cresols on different zeolites by the usual gravimetric method using Microforce balance system. The adsorption isotherms of different anilines on NaX and different exchanged zeolites were fitted in Langmuir, Nitta, and virial isotherms and various adsorption parameters were calculated. Diffusivity studies show that the rate of adsorption depends on the diameter of the molecule and the channel diameter. Diffusivities were observed to be concentration-independent and closely consistent with the Arrhenius relationship with activation energies as high as 96.6 kJ/mol. The infrared analysis of the induced bands of anilines and cresols on zeolites shows some additional bands related to N-H and O-H in anilines and cresols. The shift in these bands with respect to aniline and cresol spectra indicates the specific adsorption. Major shifts of the peaks are due to the lone pair-Lewis acid site interaction.

Juang, R.S. and Shiau, J.Y. (2002), Removal of acetone and methanol from gaseous streams in a hollow fiber absorber. Separation Science and Technology, 37 (2), 261-277.

Full Text: S\Sep Sci Tec37, 261.pdf

Abstract: Absorption removal of acetone and methanol from N₂ gas streams with liquid silicone oil was investigated in microporous hollow fiber modules. The gas flowed into the tube and silicone oil was flowed in the shell. Inlet concentrations of acetone and methanol were 1600 and 500 ppmv, respectively. All experiments were performed as a function of gas linear velocity (2.1 - 10.4 cm/sec), liquid linear velocity (0.6-5.8 cm/sec), and the operation time (10-60 min). The overall mass-transfer coefficients based on the gas phase were calculated and compared with the experimental results. The mass transfer mechanism was discussed and the height of a transfer unit in this device was finally determined.

Keywords: Absorption Removal, Acetone, Hollow Fiber Module, Mass Transfer, Methanol, Silicone Oil, Membrane-Based Absorption, Solvent-Extraction, Mass-Transfer, Gas Streams, Vocs, Permeation, Modules, Water, Air

Sağ, Y., Akçael, B. and Kütsal, T. (2002), Ternary biosorption equilibria of chromium(VI), copper(II), and cadmium(II) on Rhizopus arrhizus. Separation Science and Technology, 37 (2), 279-309.

Full Text: S\Sep Sci Tec37, 279.pdf

Abstract: A process of competitive biosorption of Cr(VI), Cu(II), and Cd(II) ions to Rhizopus arrhizus from ternary mixtures was described. Three-dimensional biosorption isotherm surfaces were used to evaluate the three-metal biosorption system performance. Triangular equilibrium diagrams, which could incorporate all the experimental data of the ternary system, were also constructed. The multimetal biosorption equilibria were described by the multicomponent Langmuir and Freundlich models. of the two models examined, the Langmuir-type model showed the best fit for the three-metal biosorption data, whereas the Freundlich-type multicomponent model did not adequately describe the biosorption results of Cr(VI) ions on R. arrhizus from ternary mixtures. The multimetal biosorption results indicated that Cr(VI) and Cu(II) significantly inhibited the biosorption of Cd(II). The Cr(VI)+Cu(II)+Cd(II) combination showed synergistic interaction on the biosorption of Cr(VI) ions.

Keywords: Biosorption, Cadmium(II), Chromium(VI), Copper(II), Multicomponent Adsorption Models, Rhizopus arrhizus, Three-Metal System, Binary Metal Mixtures, R-arrhizus, Systems, Adsorption, Biosorbent, Models, Ions, Vulgaris, Fe(III), Removal

Banat, F., Al-Asheh, S. and Mohai, F. (2002), Multi-metal sorption by spent animal bones. Separation Science and Technology, 37 (2), 311-327.

Full Text: S\Sep Sci Tec37, 311.pdf

Abstract: The multi-component metal sorption by animal bones was examined using single, binary, and ternary systems composed of Cu²⁺ Zn²⁺, and Ni²⁺. Four isotherm models, namely Freundlich, Langmuir, Sips, and Ideal Adsorption Solution Theory (IAST) were used in this study to predict the equilibrium uptake for Cu²⁺, Zn²⁺, and Ni²⁺ in binary solutions using the single adsorption constants, obtained by the single isotherm experimental data. Sorption was suppressed by the presence of other metal ions in the binary or ternary sorption processes.

The Langmuir, Freundlich, and Sips isotherm models were found to represent the experimental data of a single isotherm sorption process. Whereas, the predictions of binary sorption isotherm systems, Cu²⁺-Ni²⁺, Zn²⁺-Cu²⁺, Ni²⁺-Zn²⁺, showed good agreement with experimental data when using all models except Langmuir.

Keywords: Animal Bones, Copper, Multi-Metal, Nickel, Sorption, Zinc, Ion-Exchange, Adsorption, Biosorption, Equilibria, Removal

Ahmad, S., Khalid, N. and Daud, M. (2002), Adsorption studies of lead on lateritic minerals from aqueous media. Separation Science and Technology, 37 (2), 343-362.

Full Text: S\Sep Sci Tec37, 343.pdf

Abstract: Minerals produced by lateritic weathering have been exploited to evaluate their potential for the decontamination of lead ions from aqueous solutions and for understanding decontamination mechanism in nature. Various physico-chemical parameters such as selection of appropriate electrolyte, equilibration time, amount of adsorbent, concentration of adsorbate, effect of diverse ions and temperature were studied in order to simulate the best conditions in which the particular material could be used as an adsorbent. Maximum adsorption was observed at 0.005 mol L^-1 acid solutions (HNO₃, HCl, and HClO₄) using 0.2 g of adsorbent for 4.82×10^-5 mol L^-1 lead concentration in five minutes equilibration time, Studies show that the adsorption of lead decreases with the increase in the concentrations of all the acids. The adsorption data follows the Freundlich isotherm over the range of 2.4110^-6-9.65×10^-4 mol L^-1 lead concentration. The characteristic Freundlich constants, i.e., 1/n = 0.42±0.02 and K = 0.57±0.01 mmol g^-1 have been computed for the sorption system. The sorption mean free energy from the Dubinin-Radushkevich isotherm is 13.96±0.74 kJ mol^-1 indicating an ion-exchange mechanism of chemisorption. The uptake of lead increases with (lie rise in temperature (278-323K). Thermodynamic quantities, i.e., DeltaG, DeltaS, and DeltaH also have been calculated for the system. The sorption process was found to be endothermic.

Keywords: Adsorption, Lateritic Minerals, Lead, Removal, Atomic-Absorption Spectrometry, Heavy-Metal Ions, Trace-Metals, Sea-Water, Preconcentration, Cadmium, Sorption, Goethite, Elements, Seawater

Zouboulis, A.I., Lazaridis, N.K. and Grohmann, A. (2002), Toxic metals removal from waste waters by upflow filtration with floating filter medium. I. The case of zinc. Separation Science and Technology, 37 (2), 403-416.

Full Text: S\Sep Sci Tec37, 403.pdf

Abstract: The effectiveness of upflow filtration to remove zinc ions was studied in the present paper. Zinc ions were precipitated by employing either the conventional hydroxide route or the carbonate-enhanced route (addition of NaOH plus Na₂CO₃). Upflow column filtration with synthetic buoyant filter media was used for the subsequent solid-liquid separation of toxic metal precipitates. The experiments were conducted in semi-batch recirculated mode, using a pilot-scale upflow filtration column. The examined parameters were the necessary recirculation treatment time (3-4 hr) for the remaining concentrations of toxic metal to achieve the legislative limits (below 1 mg/L), the pH value (around 9.0), the initial concentration of the studied metal (10-50 mg/L). and the linear velocity of the waste solution under treatment within the column (10-65 m/hr). Under optimized conditions, the high efficiency and simplicity of the studied method for the removal of metal was demonstrated.

Keywords: Floating Filter Medium, Precipitation, Upflow Filtration, Zinc Removal, Sand Filter

Al-Jabari, M.E., Mousa, H. and Al-Khateeb, I. (2002), Kinetics of deposition of carbon particles on plastic spheres. Separation Science and Technology,