Microwave synthesis of zeolites from waste glass cullet using landfill leachate as a novel alternative solvent

The present work investigated the microwave (MW) zeolitization of waste glass cullet using landfill leachate as a new potential solvent. The leachate-based zeolites were synthesized in two sets, one with metal precipitation and filtration (F-zeolite) and the second one with unfiltered metal precipitates (UF-zeolite). These two cases were compared with reference zeolites produced using deionized water (D-zeolite) in terms of their characteristics. Different characterization techniques were used including XRD, EDX, SEM, FTIR, TGA, and cation exchange capacity (CEC). Presence of cations other than Na+ in leachate elevated the generation of hot spot zones and synthesized highly crystalline zeolites using unfiltered leachate. Substantial reduction in Na+ concentration due to the solid filtration also favored the production of a roughly single-phase hydroxysodalite (HS) and suppressed zeolite NaP1 formation using filtered leachate. Deionized water also produced a small fraction of zeolite NaP1 due to the lower Na+ content compared to unfiltered leachate. Zeolite synthesized using unfiltered leachate was also superior in cation exchange and water holding capacities due to its least Si/Al ratio as confirmed by EDX, TGA, and CEC results. The results from this study contribute to shed light on the efficiency of leachate application for large-scale zeolite synthesis in future prospect.