Abstract
A series of poly(2-hydroxyethyl acrylate-co-itaconic acid), P(HEA/IA), hydrogels with different HEA/IA ratio, were synthesized using free radical crosslinking/copolymerization and investigated as sorbents for Pb2+ ions from aqueous solutions. Hydrogels were characterized using DMA, FTIR, DSC, SEM and AFM. The adsorption was found to be highly dependent on hydrogel composition, solution pH, sorbent weight, ionic strength and contact time. Five isotherm models, Langmuir, Freundlich, Redlich-Peterson, Temkin and Dubinin-Radushkevich, were applied to the sorption data. The best fit was obtained with Redlich-Peterson isotherm. The separation factor, RL, value indicated favorable sorption for Pb2+ ions. The maximum sorption capacities were 392.2 and 409.8 mg/g for P(HEA/2IA) and P(HEA/10IA), respectively. Kinetic data showed best fit with pseudo-second-order model. Thermodynamic studies revealed that the reaction was exothermic and proceeds with a decrease in entropy. Moreover, P(HEA/IA) hydrogel showed the most pronounced sorption toward Pb2+ ions from environment containing Cu2+, Zn2+, Cd2+, Ni2+ and Co2+ ions. Sorption/desorption experiments, showed that the P(HEA/IA) hydrogels could be reused without significant loss of the initial properties even after three adsorption-desorption cycles.
Highlights
A series of poly(2-hydroxyethyl acrylate–co-itaconic acid), P(HEA/Itaconic acid (IA)), hydrogels with different HEA/IA ratio, were synthesized using free radical crosslinking/copolymerization and investigated as sorbents for Pb2+ from aqueous solutions
The new peak at 1554 cm–1 appeared after Pb2+ sorption, which might be a result of interactions between Pb2+ and C=O. These results indicate that –OH and –COOH groups in the P(HEA/IA) hydrogel might be involved in the sorption process
It is found that the initial concentration of metal ions, solution pH, the adsorbent mass, ionic strength and the temperature have significant influence on sorption process
Summary
A series of poly(2-hydroxyethyl acrylate–co-itaconic acid), P(HEA/IA), hydrogels with different HEA/IA ratio, were synthesized using free radical crosslinking/copolymerization and investigated as sorbents for Pb2+ from aqueous solutions. All studies clearly indicate that hydrogels based on HEA are promising sorbents for removal of heavy metal ions from aqueous solutions. The influence of initial pH of the solution, adsorbent dosage, temperature and ionic strength on the lead ions adsorption on P(HEA/IA) hydrogels were studied.
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