Sorption equilibrium of Cr(VI) ions by strong base anion exchangers with pyridine structures

Abstract

Chromate sorption on pyridine strong base anion exchangers with different functional groups (methyl, ethyl, and butyl groups), at the quaternary nitrogen atoms, was studied as a function of various initial concentrations (100 -1500 mg Cr/L) and counterion type. The studied resins in the Cl Ϫ[ form have higher Cr(VI)-retention capacities than those in the SO 4 2Ϫ form. The pyridine strong base anion exchangers showed a selectivity reversal for the sulfate and chromate anions compared to that of the commercial resins. The alkyl substituent length of the quaternary nitrogen atoms exerted a substantial influence on the Cr(VI)-retention capacity values for the resins in the Cl Ϫ form; the chromate anions preferred resins with methyl functional groups, that is, resins with a greater hydrophilic structure. For the resins in the SO 4 2Ϫ form the length of the substituent at the quaternary nitrogen atom had only a negligible influence on their Cr(VI)-retention values.

Removal of Cr(VI) onto functionalized pyridine copolymer with amide groups

“…In our case the synthesized resins have a reversal selectivity namely, CrO 4 2− > SO 4 2− > Cl − for the concentration range of 22-119 mg L −1 . The same behavior of pyridine strong base anion exchange resins in the competitive adsorption system of chromate/sulfate was observed in the previous studies [21]. The reason for the chromium selectivity over sulfate anion is due to the transition metal anion adsorption on the bonds of the pyridine ring, formation a sandwich arrangement with the chromium anion and functional groups attached to the quaternary nitrogen atom.…”

“…Removal of Cr(VI) from cooling water and ground water by ion exchanger has been investigated by many researchers and their results have been published [9][10][11][12][13][14][15][16][17][18][19][20][21][22]. The main advantages of the ion exchange are recovery of the metal, selectivity, less sludge volume produced and the meeting of strict discharge specification.…”

“…Previous work focused on the thermodynamic and kinetic studies of Cr(VI) retention from the aqueous solutions on the pyridine resins with different lengths of alkyl substituents namely, methyl, ethyl and butyl functional groups at the quaternary nitrogen atom [20][21][22]. Chromium retention capacity depends on the ionic form of the strong base anion exchangers and the substituent type at the quaternary ammonium atoms.…”

Adsorption of cefotaxime sodium salt on polymer coated ion exchange resin microparticles: Kinetics, equilibrium and thermodynamic studies

“…Initially ion exchange resins were developed for industrial and agricultural applications, such as waste water purification (Dulman, Simion, Barsanescu, Bunia, & Neagu, 2009;Neagu, Untea, Tudorache, & Orbeci, 2004) and separation of different gases. More recently they have been used in pharmaceutical and medical fields for isolation and purification of pharmaceutical active ingredients (Belakhov & Momot, 1983) or as functional excipients in dosage form (taste masking agent, tablet disintegrant, drug stabilization agent and sustained release agent) and or active drug ingredients.…”

Removal of hexavalent chromium by new quaternized crosslinked poly(4-vinylpyridines)

“…The previous work focused on the thermodynamic and kinetic studies of Cr(VI) removal from aqueous solutions by the pyridine resins with different lengths of alkyl substituent namely, methyl, ethyl, butyl or amide functional groups at the quaternary nitrogen atom [43][44][45][46]. Chromium retention capacity depends on the ionic form of the strong base anion exchangers and the substituent type at the quaternary ammonium atoms.…”