Poly (AMPS-co-IA) hydrogels playing dual role: acidity regulator and adsorbent for Cr(VI) adsorption

Removal of Cr(VI) from aqueous solution is performed by using Poly (AMPS-co-IA) hydrogels and their disassembled form and the results are compared. Optimum conditions of adsorption such as temperature and contact time was studied along with fundamental thermodynamic, kinetic and equilibrium studies. It was found that these hydrogels in both their forms do not require any external agent to maintain the acidic pH of the medium, which is the favourable condition for Cr(VI) removal. The ability of these hydrogels to retain the acidic pH was determined by Pzc studies. The pzc values were 2.4 and 3.0, respectively for disassembled and assembled hydrogels. The reason behind this acidic value was found as the presence of Sulphonic acid and Carboxylic acid functional groups in the molecular formula of the hydrogels. Q(max) value were determined for assembled hydrogels as 250 mg/g and that for its disassembled counterpart it was raised to 333.3 mg/g. Desorption studies were carried out in order to estimate the reusability of the hydrogels. SEM, ToF-SIMS studies are reported.