Sustainable and low-cost SUZ-4 synthesis and its application for Cd2+ removal

Abstract

High value-added utilization of industrial waste is important for environmental protection and sustainability. The objective of this study was to recycle industrial wastes, silica fume (SF) and aluminium ash (AA) as raw materials to substitute chemicals for sustainable and low-cost SUZ-4 zeolite (L-SUZ-4) synthesis in one pot. The synthesis parameters to obtain pure L-SUZ-4 were optimized as xKOH(x = 7.84–9.33):yAl2O3(y = 0.81–1.10):2.6TEAOH:21.2SiO2:zH2O(z = 330.72–712.32) at 150 °C for 96 h. The notably high yield of L-SUZ-4 (up to 85%) indicated that silicon and aluminium species in SF and AA are not only easy to be activated but also liable to be incorporated into the zeolitic framework. Exploration of L-SUZ-4 synthesis process by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) characterizations indicated that the synthesis follows the liquid phase transition mechanism. It can also be observed that the complete dissolution of SF is the rate-determing step during the induction period. Meanwhile, the adsorption ability of L-SUZ-4 for Cd2+ in water was first investigated. A notably maximized adsorption amount (qmax = 263.68 mg/g) of L-SUZ-4 for Cd2+ was obtained, which is higher than the other adsorbents investigated in this work or those described in the literature. The sustainable production and outstanding adsorption performance of L-SUZ-4 make it a very promising adsorbent for heavy metal removal with practical application prospects, which is the typical case of “waste to treat waste”.