pH Sensitive Dual Cross-Linked Anionic and Amphoteric Interpenetrating Network Hydrogels for Adsorptive Removal of Anionic and Cationic Dyes

The contamination of water by organic dye compounds are worldwide environmental problem due to their highly toxic nature. To address this environmental issue, a simple technique with highly efficient dye removal was developed to prepare pH- sensitive dual-crosslinked anionic and amphoteric interpenetrating network (IPN) hydrogels based on Na-carboxymethyl cellulose (Na-CMC) using jute stick-based cellulose. Crosslinked Na-CMC and crosslinked κ-carrageenan (KC) were interlaced by H-bonding in anionic IPN hydrogel (An-gel), but crosslinked Na-CMC and crosslinked Chitosan (CS) were interlaced by electrostatic interaction in amphoteric IPN hydrogel (Am-gel). In various operating conditions (pH, temperature, etc.) An-gel displayed a higher number of swelling ratios of about 2560% at pH 7.2 and Am-gel of about 1874% at pH 5.5. Based on the point of zero charge, An-gel achieved the maximum removal efficiency of 81.62 % for methylene blue (MB) at pH 7.2, whereas Am-gel achieved 85.38% removal efficiency for eosin yellow (EY) at pH 5.5. The adsorption kinetics of IPN hydrogels followed a pseudo-second order model and best fitted by Langmuir isotherm model. The removal efficiency of MB and EY decreased slightly with increasing temperature. The values of ΔH°, ΔG°, and ΔS° indicated an exothermic, spontaneous, and disordered adsorption process.