Functionalization of a cast NaAl/binary ZnO/SiO2 nanohybrid with amine and Schiff base ligands as an adsorbent of divalent cations in water system

Abstract

Abstract Casting method was used to synthesize a novel sodium alginate nanohybrid functionalized with aminated ZnO/SiO2 Schiff base for adsorption of nickel and copper divalent cations in single and binary water system. The cast Schiff base nanohybrids were investigated using FESEM, XRD, BET, FTIR, TGA and XPS analyses. The influence of unfunctionalized binary ZnO/SiO2 nano oxides and aminated Schiff base ligands formed by the reaction between salicylaldehyde and O-phenylenediamine on the adsorption of divalent nickel and copper ions was evaluated. The results confirmed that the aminated Schiff base ligands led to a higher adsorption ability of cast nanohybrids containing interaction of divalent cations with nitrogen and oxygen atoms, carboxyl and hydroxyl groups. The adsorption kinetics and isotherm for both ions followed double-exponential model and Redlich-Peterson model, respectively. The maximum monolayer capacity was found to be 249.8 mg/g for copper cation and 96.4 mg/g for nickel cation. The endothermic and spontaneous adsorption with entropy increment was found by thermodynamic investigation. Furthermore, the synthesized Schiff base adsorbent could be easily reused over five times. The simultaneous adsorption in a binary system exhibited a higher adsorption selectivity of the cast Schiff base nanohybrid for copper cation compared to nickel cation.