High value-added utilization of silica fume to synthesize ZSM-35 zeolite membrane for Cd2+ removal

A solid waste-based ZSM-35 zeolite membrane was synthesized using silica fume waste as Si source and adjusting Si/Al molar ratio of 10 with metakaolin by hydrothermal route, and applied for removal of toxic and harmful Cd2+ from aqueous solution. The XRD, FESEM and BET results indicated that the synthesized ZSM-35 zeolite membrane with high crystallinity, lamellar morphology, high microporosity and BET specific surface area. The ZSM-35 zeolite membrane showed the high separation performance for the heavy metal Cd2+ from aqueous solution due to the synergistic effect of adsorption and ion rejection. The rejection rate of Cd2+ was up to 99.22% when the Cd2+ concentration was 500 mg/L and the system kept the negative pressure of 0.04 MPa. This provides a new approach for high value-added recycling of silica fume waste and effective removing heavy metal ions.