Keywords: RB5; Reactive Black 5 dye; CHs; chitosan (non-crosslinked chitosan sorbent in the form of hydrogel beads); CA; crosslinking agent; CIT; trisodium citrate; ECH; epichlorohydrin; EGDE; ethylene glycol diglycidyl ether; GLA; glutaraldehyde; OA; oxalic acid;