Seed-Assisted Crystallization in the Hydrothermal Synthesis of FAU Zeolite from Acid-Treated Residue Glass Powder

A simple and low-cost synthesis assisted by seed crystals has been proposed to convert residual colorless glass powder into a Na-X zeolite. For this purpose, the optimal parameters for acid leaching of glass powder were studied to remove impurities that could interfere with the crystallization process. Then, the hydrothermal syntheses were supported by Na-X seed crystals (0% to 5%, wt.) to induce the growth of zeolite X, evaluating the crystallization time (12 h to 48 h) and the variation of the silicon source (acid-treated and untreated residues). The formation of the faujasite as the main phase, with a higher degree of structural order and microporosity, was observed with the previous treatment in the residue, a higher seed loading, and a shorter crystallization time. On the other hand, a phase competition between faujasite, gismondine, Linde type-A, and sodalite structures was observed in the zeolites synthesized from the untreated residue. In this case, the high seed loading and the longer synthesis time allowed the correct targeting of the faujasite structure with low structural order and micro/mesoporous properties. Furthermore, interzeolite transformations occur in all syntheses, where the framework type synthesized was influenced by the presence of a specific ion as a mineralizing agent.