Preparation of novel B/ZnO/zeolite nanocomposites by simple combustion method for enhanced dye removal in an aqueous environment.

Abstract

In this study, the mixture of zinc acetate dehydrates and boric acid was pyrolyzed in zeolite X to prepare novel B/ZnO/zeolite nanocomposites for the enhanced removal of tartrazine (TA) in aqueous environment. The composites are porous material with a relatively large pore size (35.3 nm). The surface area of the composite (19.72 m²g^-1) is smaller than that of zeolite (248.78 m²g^-1), but its adsorption capacity is quite high (q_maxof 97.6 mg g^-1). The factors influencing the adsorption process were investigated in detail. Under the optimal conditions (the initial dye concentration of 20 mg l^-1, the adsorbent content of 0.5 g l^-1, pH equal 6, and the temperature of 25°C), the removal efficiency (R_e) was 97.5%. The first and second-order equations were used to model the kinetic adsorption. The Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich models were used to study isothermal adsorption. In addition, the thermodynamic of adsorption was also investigated. The ΔH^oof -52.423±2.306 kJ mol^-1indicates the exothermic process and the negative ΔG^oindicates a spontaneous process. At low temperatures, the adsorption of TA proceeds smoother and more effectively, and the negative ΔS^o(-129.638 7.376 J·mol^-1·K^-1) indicates a decrease in the degree of freedom of the adsorbed species. The adsorption mechanism was also proposed.