Development of chitosan based hybrid hydrogels for dyes removal from aqueous binary system

Crosslinked hydrogel with glutaraldehyde (HyCG) and hydrogel with activated carbon (HyCC) were developed, characterized and applied for the adsorption of Food Blue 2 (FBL2) and Food Red 17 (FR17) from aqueous binary system. The pH effect (2 to 8) was verified and, in the more appropriated condition, kinetic tests were realized. Adsorption-desorption cycles were performed. The most appropriate way to prepare HyCG was using 4.0% chitosan and 1.5% glutaraldehyde. It was found that pH 3 was the more adequate condition for dyes adsorption. In all experiments, HyCC presented high adsorption capacity. The maximum adsorption capacities were 155.1 and 133.9 mg g− 1 for FBL2 and FR17, respectively using HyCC as adsorbent. Adsorption-desorption were performed and the best eluent was NaOH 0.01 mol L− 1 with 5 cycles of reuse. The results revealed that the insertion of activated carbon on the chitosan hydrogel structure provided an improvement in the adsorption performance.