EFFECT OF IONIC AND COVALENT CROSSLINKING OF HYDROGEL CHITOSAN BEADS ON THE ADSORPTION EFFICIENCY OF BASIC VIOLET 10 AND BASIC GREEN 4 DYES FROM AQUEOUS SOLUTIONS

Abstract

This work investigated the adsorption efficiency of Basic Violet 10 (BV10)and Basic Green 4 (BG4) dyes on ionically and covalently crosslinked chitosan hydrogel beads. The tested ionic crosslinkers were sodium citrate, sodium tripolyphosphate, and sulphosuccinic acid, while the covalent crosslinkers were glutaraldehyde, epichlorohydrin, and trimethylolpropane triglycidyl ether. The scope of the work included investigation of the effect of pH on the adsorption efficiency of dyes and the maximum adsorption capacity of crosslinked chitosan adsorbents. The maximum adsorption capacity of the non-crosslinked chitosan adsorbent was 2.94 mg/g and 44.32 mg/g for BV10 and BG4, respectively. Ionic crosslinking, regardless of the type of crosslinking agent, reduced the adsorption ability of hydrogel chitosan adsorbents in relation to cationic dyes (Qmax = 1.84-2.49 mg/g for BV10; 37.21-38.90 mg/g for BG4). Covalent crosslinking of chitosan slightly increased its adsorption capacity only for BV10 (Qmax = 3.59-3.81 mg/g for BV10; 39.15-40.62 mg/g for BG4).