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ABSTRACT: The effects of basic strength and steric hindrance of gels modified by dimethylamine, diethylamine, di-n-octylamine and di-2-ethylhexylamine, respectively, on rhenium (Re(VII)) adsorption capacity and selectivity were discussed. By comparing with the adsorption of other coexisting metals, such as Mo(VI), Cu(II), Pb(II), Fe(III), Zn(II), Mn(VII) and Ni(II), the gel modified by di-n-octylamine (DNOA-OCS) showed a high affinity for Re(VII) at higher hydrochloric acid concentration (CH+⩾1.0molL-1), and the maximum adsorption capacity was 98.69mgg-1. This article not only described the adsorption behavior but also suggested isotherms, kinetics and thermodynamics of Re(VII) onto the DNOA-OCS gel in an aqueous medium using several models. Further study on adsorption of rhenium in a fixed-bed column packed with the DNOA-OCS gel under continuous and recirculating modes could confirm that the corn stalk gel modified by di-n-octylamine could be used as the adsorbent of Re(VII) from Mo-containing wastewater.
Bioresource technology 02/2013; 133C:546-554. · 4.25 Impact Factor
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ABSTRACT: Brown algae Laminaria japonica was chemically modified with sulfuric acid to obtain a crosslinked brown algae gel (CAS). The CAS gel showed a high affinity for Re(VII) comparing with other biomass gels, and the maximum adsorption capacity was evaluated as 37.20mgg(-1) in case of pH 6, which could be explained by their different adsorption mechanisms. The adsorption equilibrium, kinetics and thermodynamic study for Re(VII) on the CAS gel was discussed in detail by the several models, such as Langmuir, Freundlich, Temkin and Dubinin-Radushkevich model for kinetics analysis, the pseudo first, the second-order, the Elovich and intraparticle diffusion equation for equilibrium analysis. Reutilization of the CAS gel was confirmed up to three adsorption-elution cycles in column-mode operation with no damage of gel, packed in the column. The result also provides a new approach for the recovery of Re(VII) from Re-containing wastewater by using the modified brown algae gel.
Bioresource technology 10/2012; 127C:464-472. · 4.25 Impact Factor
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ABSTRACT: Persimmon waste was chemically modified by crosslinking with concentrated sulfuric acid to obtain a novel kind of adsorption gel, which was termed as crosslinked persimmon tannin (CPT), hereinafter. The adsorption behaviors of Mo(VI) with other coexisting metal ions onto the CPT gel were investigated. The gel exhibited selectivity only for Mo(VI) ions evidenced by the high value of separation factor of molybdenum and rhenium (β(Mo/Re)=164.37), and the adsorption mechanism of Mo(VI) as a multispecies was studied. The molybdenum adsorption behavior conforms to the Langmuir model with a remarkably high adsorption capacity of 0.56 mol/kg. A kinetic study for the adsorption of molybdenum at various temperatures confirmed that the endothermic adsorption process followed pseudo-second order kinetics. Moreover, its excellent adsorption properties and applicability for Mo(VI) were demonstrated by the removal and separation of Mo(VI) from different Mo-Re containing industrial wastewaters.
Bioresource technology 07/2011; 102(13):6857-62. · 4.25 Impact Factor
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ABSTRACT: The interfacial behavior of Cyanex 272 has been investigated using the Du Nouy ring method. Different adsorption isotherms such as the Gibbs and Szyszkowski isotherms have been found as fitting well to the experimental data. The values of interfacial excess at the saturated interface increase in the following order: n-heptane > cyclohexane > CCl4 > toluene > benzene > chloroform, explained according to the stronger solution effect of aromatic hydrocarbon. The effects of temperature, acidity, and ionic strength of the aqueous phase on the interfacial activity of Cyanex 272 are also examined and explained in detail. Moreover, the reaction orders against Cyanex 272 predicted from the interfacial tension isotherms are in agreement with the order determined experimentally, which suggests that the interfacial activity of Cyanex 272 can provide enough strong evidence quantitatively supporting the interfacial mechanism.
Separation Science and Technology 03/2011; 46(6):959-964. · 1.09 Impact Factor
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ABSTRACT: Astringent persimmon was chemically cross-linked by formaldehyde to obtain a novel kind of adsorption gel, which was named as APF gel. The adsorption behaviors of Mo(VI) and Re(VII) along with other coexisting metals onto the APF gel were studied in the present paper. The APF gel was found to be effective for the adsorption of Mo(VI) while the gel is almost completely inert toward rhenium and calcium over the whole hydrochloric acid concentration region. The APF gel has a low affinity for iron, copper, lead, nickel, manganese and zinc ions when the concentration of HCl is higher than 1 mol/L. The gel exhibited selectivity only for Mo(VI) with a remarkably high adsorption capacity 1.05 mol/kg, and the adsorption behavior obeys the Langmuir model. According to the thermodynamic and kinetic studies, the endothermic adsorption process followed pseudo-second order kinetics. Also, its excellent adsorption characteristics for Mo(VI) were confirmed by the adsorption and elution tests using a column packed with the APF gel. The result provides a new approach for the recovery of Mo(VI) from a industrial waste effluent.
Journal of hazardous materials 02/2011; 186(2-3):1855-61. · 4.14 Impact Factor
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Separation Science and Technology 01/2006; 41(8):1725-1739. · 1.09 Impact Factor
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Solvent Extraction and Ion Exchange 01/2006; 24(2):165-176. · 2.02 Impact Factor
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Separation Science and Technology 01/2006; 41(1):167-178. · 1.09 Impact Factor
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ABSTRACT: In this paper, interfacial tension of Cyanex 302 is measured by a Sigma-701 tensiometer and the adsorption parameters are calculated according to the Gibbs and Szyszkowski adsorption isotherms. The interfacial adsorbed behavior of Cyanex 302 is investigated. The results demonstrate that the dimer is the predominant species in the bulk organic phase; however, the monomer is adsorbed at the interface and more interfacially active. The effects of aqueous pH, ion strength, and temperature on the interfacial activity of Cyanex 302 in heptane are discussed and explained in detail. The lower interfacial activity of Cyanex 302 in aromatic hydrocarbon than in aliphatic hydrocarbon has also been determined. The values of interfacial excess at the saturated interface increase in the order n-heptane>cyclohexane>toluene>benzene, which is consistent with the order of extractability of lanthanum by Cyanex 302 in these diluents. The interfacial activity data are used to discuss the kinetic mechanism of lanthanum(III) extraction. It is shown that an interfacial mechanism is very probable, and the extraction limiting step is the reaction between the Cyanex 302 molecules in the organic phase sublayer and the adsorbed intermediate complex.
Journal of Colloid and Interface Science 10/2005; 290(1):235-40. · 3.07 Impact Factor
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Separation Science and Technology 01/2005; 40(11):2325-2336. · 1.09 Impact Factor
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ABSTRACT: The extraction kinetics of rhenium(VII) with mixtures of tri-alkylamine (N235, R3N, R = C8 − C10) and tri-n-butylphosphate (TBP) dissolved in heptane has been investigated by constant interfacial cell with laminar flow. The influence of stirring speed, temperature, specific interfacial area, extractant concentration and chloride concentration on the extraction rate has been studied. It is concluded that the extraction of Re(VII) takes place at the liquid–liquid interface, while the extraction regime belongs to kinetic control by chemical reaction. The extraction rate equations and the rate-determining step have been obtained under the experimental conditions, and the extraction rate constant is calculated. The results are also compared with the system with N235 alone as extractant which shows that the Re(VII) extraction rate is enhanced and the activation energy is decreased with the mixtures of N235 and TBP. The separation of Re(VII) from Mo(VI) by kinetics with the mixtures of N235 and TBP is similar to that with N235 alone. Nevertheless, the separation of Re (VII) from Mo(VI) is better under kinetic conditions than under thermodynamic equilibrium conditions.
Hydrometallurgy 100:110-115. · 2.03 Impact Factor
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ABSTRACT: Extraction and separation of yttrium from the rare earths in chloride medium using sec-octylphenoxy acetic acid (CA-12), tri-n-butyl phosphate (TBP) as modifier, in kerosene has been investigated. The separation coefficients, β, were obtained and the extraction selectivity has been enhanced when compared with that of naphthenic acid. The experimental results indicated that CA-12–TBP system could be employed to separate yttrium from rare earths. Fractional extraction (15 stages for extraction and 10 stages for scrubbing) was studied, the raffinate of the first stage was abundant in purity yttrium of 99.5%, with a yield of >95%, percentage of yttrium in the mixture rare earths was less than 5% in the loaded organic phase of the 25th stage and loaded capability was about 0.2 mol/L.
Separation and Purification Technology.
