Synthesis of zeolitic materials from waste porcelain at low temperature via a two-step alkali conversion

An attempt was made to convert waste porcelain into zeolitic materials using a two-step alkali conversion. During the first step, under optimum conditions for both high Si extraction from the waste and residue with high cation exchange capacity (CEC), the concentration of Si extracted from the waste was ca. 26,000 mg/L, and the residue contained zeolitic (Na–P1, and hydroxysodalite) materials and residual phases (quartz, and mullite), which had high CEC (170 cmol/kg). In the second step, Na–A, Na–X, and Na–P1 zeolites were synthesized from the extracted solution during the first step, with addition of aluminate solution. With increasing Si/Al molar ratio of the solution, the product phase changed from Na–A → Na–X → Na–P1, and the Si content increased in the solution.