Abstract
A novel cross-linked polyzwitterion (CPZ) was synthesized via cycloterpolymerization of N,N-diallyl-N-suifopropylammonioethanoic acid (92.5 mol%), a cross-linker 1,1,4,4-tetraallyipiperazinium dichloride (7.5 mol%), and sulfur dioxide (100 mol%) in the presence of azoisobutyronitrile in dimethylsulfoxide at 60 C. CPZ, upon treatment with NaOH, was converted into a cross-linked polyzwitterion/anion (CPZA). The experimental data for the adsorption of Sr2+ on CPZA fitted the pseudo-second-order kinetic model and Freundlich as well as Temkin isotherm models. The adsorption process was spontaneous and exothermic in nature with negative values for both Delta G and Delta H. The low activation energy of 7.18 kJ/mol indicated the adsorption as a favorable process. The removal for the initial concentrations of 200 ppb and 1000 ppb (i.e., 1 ppm) of Sr2+ ions was observed to be 87% and 92%, respectively. An efficient synthetic access to the resin and excellent adsorption capacity and desorption would enable its use in the treatment of radioactive nuclear waste containing Sr2+ ions. The CPZA provided an opportunity to test the efficacy of a zwiiterionic/anionic group in the removal of SP2+ ions in low concentrations. (C) 2013 Elsevier Ltd. All rights reserved.