Synthesis of zeolite from coal fly ash with aluminum dross using alkali fusion

Abstract

Coal fly ash (CFA) and aluminum dross are industrial wastes that required proper treatment and disposal. Several studies have been focusing on reusing CFA to produce zeolites; a porous crystalline materials with various applications. Nonetheless, the applicability of aluminum dross in zeolite synthesis has yet to be determined. In this study, CFA and aluminum dross were used for the synthesis of zeolite by akaline fusion. Aluminum oxide, a commonly used aluminum source, was also tested for comparison. Optimal condition of zeolite synthesis was determined based on characteristics of the products such as cation exchange capacity (CEC). Zeolite A was generated in this study. In the case of aluminum dross, optimal synthesis condition was obtained at 600 ˚C fusion temperature followed by crystallization at 80 ˚C. Although the observed CEC was relatively lower than those of the zeolites synthesized from aluminum oxide, their CEC values were still comparable. The cadmium and methylene blue (MB) adsorptions of the synthesized zeolites with high CEC values (P680, P780, D680, and D780) were then investigated. Among the three isotherm models including linear regression, Langmuir isotherm, and Freundlich isotherm, the data from cadmium adsorption by the synthesized zeolites fitted well with the Freundlich isotherm. On the contrary, MB adsorption could not be fitted with any models used in this study. These results suggest that zeolite A can be obtained from CFA and aluminum dross, and its capability in cadmium and MB removal was similar to the zeolite produced from aluminum oxide.