NaY zeolite was synthesized from kaolin/dimethyl sulfoxide (DMSO) intercalation composites using an in situ crystallization technique. The effects of the intercalation ratios and the amounts of the kaolin/DMSO intercalation composite on the synthesis of an NaY zeolite molecular sieve were studied. The samples were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, differential thermal analysis, N2 adsorption–desorption and scanning electron microscopy. In the in situ synthesis system, when the kaolin/DMSO intercalation composite was added, pure NaY zeolite was formed. By increasing the amount of kaolin/DMSO intercalation composite added, the crystallinity of the samples increased, and after reaching the maximum amount of kaolin/DMSO intercalation composite added, the crystallinity decreased with further increases of the amount of kaolin/DMSO intercalation composite added. To higher intercalation ratio, the crystallinity can be greatly improved at the lower addition content. At an intercalation ratio of 84%, the added amount of kaolin/DMSO intercalation composite was 2.5% and the crystallinity of the NaY zeolite molecular sieve reached a maximum value of 45%. At intercalation ratios of 55% and 22%, the amount of kaolin/DMSO intercalation composite added was 15% and the crystallinities of the NaY zeolite molecular sieves were 44% and 47%, respectively. The NaY zeolite has good thermal stability and a particle diameter of ~0.5 μm. The Brunauer–Emmett–Teller (BET) specific surface area and pore volume of the sample were 519 m2 g–1 and 0.355 cm3 g–1, respectively.
In this paper, the covalent organic polymer of enaminone was modified by thiourea, and the covalent organic polymer of thiourea (CTOP) was synthesized by simple solvothermal method. At 25 ℃, the adsorption capacity of the polymer for trivalent gold ion is 2372.7 mg/g. In the mixed aqueous solution of divalent cadmium ion, trivalent gold ion, divalent copper ion, divalent cobalt ion and divalent nickel ion, CTOP can only adsorb trivalent gold ion, which indicates that CTOP has high selective adsorption performance for trivalent gold ion. In addition, CTOP material still maintains high adsorption performance after five adsorption cycles, which proves that the adsorption material has good reusability. According to the experimental results of adsorption kinetics and thermodynamics, the adsorption process of CTOP for trivalent gold ions conforms to the quasi second order adsorption model and Langmuir adsorption model, that is, the adsorption process of CTOP for trivalent gold ions is single-layer chemical adsorption. CTOP not only has strong adsorption and selectivity to Au (Ⅲ), but also has good reusability. Therefore, it is an ideal environmental functional material, which can be used to separate and enrich trivalent gold ions in wastewater.
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