Abstract
In this study, we analyzed the sorption and desorption of three dyes, namely, acid red 18 (AR18), basic violet 10 (BV10) and direct black 22 (DB22), onto three sorbents of waste material chosen from different branches of industry, namely, chitosan, modified sawdust and fly ash — sorbent 1: chitosan beads, sorbent 2: modified sawdust immobilized onto chitosan and sorbent 3: fly ashes immobilized onto chitosan. Each of these sorbent materials was investigated to determine multiple application feasibility in sorption and desorption cycles. Our study demonstrated that the number of sorption/desorption cycles depended on both the dye and the sorbent. The highest number of sorption/desorption cycles (i.e. n = 7) was achieved for a combination of BV10 and sorbent 2, i.e. modified sawdust immobilized onto chitosan. A comparable effectiveness of six cycles was observed for a combination of AR18 and sorbent 1 (chitosan beads). However, only one sorption/desorption cycle was achieved for sorbent 3, irrespective of the type of dye used.