Juan Liu,Zhujian Huang,Jie Sun,Yixuan Zou,Beini Gong
In this study, thiourea reduced graphene oxide/NaA zeolite composite (tGO-Zeo) was successfully prepared by a facile two-step synthetic route and used as an efficient adsorbent for removal of Cd(II) from aqueous solution. Characterization of the composite material showed that tGO was entrapped within zeolite crystalline particles and intimately interacted with the zeolite framework. Furthermore, the presence of tGO considerably reduced zeolite crystal size and altered crystal morphology, turning cubic zeolite crystals of micrometer size into nanometer irregular particles. Batch adsorption experiment for Cd(II) removal was conducted and the adsorption performance of tGO-Zeo and Zeo (zeolite) were determined. It was shown that doped tGO significantly enhanced the adsorption capacity of zeolite by 31.54%. The adsorption mechanism differs for tGO-Zeo and Zeo, and tGO-Zeo has higher affinity for Cd(II). The adsorption capacity of tGO-Zeo with a tGO doping amount of 1.26% (wt%) was estimated to be 196 mg/g (1.74 mM/g) at 30 °C and superior to most previously reported zeolite based composites, which often contain large amounts of dopants . The effects of pH and ionic strength on adsorption suggest that ion exchange and coordination are responsible for Cd(II) adsorption by tGO-Zeo. Humic acid can slightly increase Cd(II) adsorption performance of tGO-Zeo, which may be due to tGO-Zeo—humic acid—Cd(II) complexes formation. Therefore, tGO-Zeo composite is a cost-effective and eco-friendly adsorbent for efficient removal of Cd(II) ions from aqueous solutions.
Zeolite membranes have excellent application prospects in the separation of mixtures with molecular-level differences; however, the uneven distribution of active ingredients on the support causes defects in the zeolite membranes, limiting their industrial applications. In this study, compact NaX and NaA zeolite membranes with perfect pervaporation performance were prepared in reusable saturated membrane synthesis solutions. These saturated membrane synthesis solutions not only provided sufficient Si/Al components for the even growth of zeolite on the support, but also reduced the random deposition of zeolite particles on the support by reducing the formation of zeolite particles in the bulk solution, improving the quality of the resulting zeolite membranes. The separation factors of the obtained NaA and NaX zeolite membranes were greater than 10000 for the water/ethanol and methanol/MTBE mixtures, respectively. Moreover, the saturated synthesis solutions could be reused multiple times to synthesize zeolite membranes after nutrient supplementation, saving resources and reducing environmental pollution. This study presents reusable solutions for synthesizing compact zeolite membranes, promoting the development of membrane technology for environmental protection and energy conservation.
危险品化学品经营许可证（带存储）