Poly(ammonium/pyridinium)-chitosan Schiff base as a smart biosorbent for scavenging of Cu2+ ions from aqueous effluents

Chitosan Schiff bases (CSBs) decorated with ammonium or pyridinium motifs for recyclable biosorption of Cu2+ ions from aqueous effluents were tailored by grafting of salicylaldehyde ionic liquids (Sal-ILs) onto chitosan surface. Biosorption capacity of poly(ionic-salicylidene) CSBs (PISCSB1, 2) was compared with chitosan and poly (neural-salicylidene) CSBs (P SC SB). The ionic salicylidene-functionalized chitosan, poly(pyridinium)salicylidene chitosan Schiff base (PISCSB2), exhibited excellent adsorption capacity (99.1%), in comparison to chitosan (85%) and PSCSB (95%). Biosorption of Cu2+ ions onto PSCSB followed pseudo-first-order kinetic model while onto chitosan (CS) and PISCSB1,2 followed pseudo-second-order kinetic model. However, Cu2+ ions biosorption onto all biosorbents fitted Langmuir adsorption isotherm model. Negative values of Delta G degrees and Delta H degrees confirmed the spontaneity and exothermic behavior of adsorption process. The new biosorbents could be successfully regenerated in aqueous 0.01 M EDTA solution with negligible loss in their adsorption capacity. Consequently, our new chitosan-based biosorbents may offer promising green and renewable scavengers for Cu2+ ions from wastewater.