Green Synthesis of Mesoporous Sodalite and Graphene Oxide Hybrid Sodalite Using Lithium Silica Fume Waste

Abstract

Mesoporous zeolite and hybrid zeolite are indispensable materials for the chemical industry; however, their fabrication always involved high production cost, long times, and adverse environmental impact. Here, we report a vacuum–ultraviolet (VUV)-initiated reactive oxygen species (ROS) route for the green and fast synthesis of mesoporous sodalite (SOD) zeolite and a hybrid SOD zeolite directly from lithium silica fume (LSF) waste without template. The fast synthesis is based on in situ generation of ROS (e.g., •OH, O2•–, and 1O2) in amorphous precursor using VUV irradiation, which significantly shortens the crystallization process to produce SOD with high crystallinity and abundant mesopores at low temperature. Further addition of graphene oxide (GO) during SOD preparation could not only inhibit the zeolite aggregation but also initiate electron transfer to further induce generation of superoxide ion radicals (O2•–), and yield a stable hybrid SOD zeolite with narrower band gap within 2 h. The physicochemical properties of the produced SOD and hybrid SOD were carefully studied, whereby electron paramagnetic resonance (EPR) was used to probe the existence of ROS which promote crystallization process. The metal ion adsorptive experiments revealed zeolites produced own superior ion-exchange capacity toward copper ion. This study opens up a new avenue to enable green and ultrafast synthesis of zeolites and hybrid zeolites with improved time efficiency.