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

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.