Preparation of Sodalite at Room Temperature for Enhanced Zn2+ Removal from Aqueous Solution

Abstract

Sodalite products were synthesized with varying hydrogel Al₂O₃/SiO₂ ratio by a hydrothermal route. The results revealed that spherical particles consisted of small crystallites were obtained after 10 h of room-temperature crystallization; while with the same hydrogel composition, the sample synthesized at 90°C for 10 h was large lepispherical particles. In compare with sample obtained at elevated temperature, sodalite crystals synthesized under room temperature exhibited better Zn²⁺ ions adsorption performance, and the maximum adsorption capacities were measured to be 51.2, 54.3, 57.1, and 61.6 mg/g for the sodalite synthesized with hydrogel Al₂O₃/SiO₂ ratios of 0.43, 0.55, 0.68 and 0.84, respectively. The reasons would be attributed to its larger surface area, specific pore structure, along with more available active sites of adsorbent. Moreover, the adsorption isotherms and kinetics analysis displayed that Langmuir model and pseudo-second order model matched well with the adsorption processes. Sodalite products obtained under room temperature are potential adsorbents for the removal of Zn²⁺ as low-cost materials used for treating sewage in the future.