Effective removal of Th4+, Pb2+, Cd2+, malachite green, methyl violet and methylene blue from their aqueous solution by amylopectin dialdehyde-Schiff base

In the present study, amylopectin was oxidized to amylopectin dialdehyde by selective cleavage of C2-C3 bond of anhydroglucose units in the amylopectin chain by sodium metaperiodate to generate two aldehyde groups and modified to Schiff bases by the reactions with ethanolamine, hydrazine and semicarbazide. The well characterized Schiff bases were used as adsorbents for Th4+, Pb2+, Cd2+ ions and three cationic dyes namely malachite green, methyl violet and methylene blue. Among the three Schiff bases, amylopectin dialdehyde-ethanolamine (APDA-EA) showed stronger and selective adsorbent towards Th4+ ions and malachite green dye. The adsorption data was found to follow pseudo second order kinetics and Langmuir adsorption isotherm. The maximum adsorption capacity of APDA-EA towards Th4+ ions was 94.68 mg/g and towards malachite green dye it was 89.84 mg/g. The greater selectivity of APDA-EA towards Th4+ ion was explained theoretically by Density Functional Theory calculations.