Microporous silica-supported cation exchanger with superior dimensional stability and outstanding exchange kinetics, and its application in element removal and enrichment

摘要

Ion exchange resins are widely applied for their unique advantages. However, traditional resins confront the troubles as slow adsorption kinetics and high column pressure, which greatly limit their further industrial utilization. In this work, a porous silica was implanted into the organic resin via an in-situ solution polymerization method, followed by grafting the sulfonic group onto the silica-supported body. This material was then characterized by FT-IR, TG-DSC, SEM-EDS, acid-base titration and BET, and finally evaluated by the batch and column tests. The characterization suggested that the silica-supported cation exchanger (SiPS-SO3Na) was successfully synthesized with the total exchange capacity reaching 1.41 meq/g; The organic composition distributed homogeneously in the channel of the silica particle and occupied 27.9 wt% of this composite. Owing to the large specific surface area (79.2 m(2)/g) and the protection of the silica framework, SiPS-SO3Na showed superior advantages in adsorption kinetics and dimensional stability versus the traditional resins. The exchange speed of SiPS-SO3Na was 12-fold faster than that of commercial product 732, and the swelling rate was found close to 0 while that of 732 exceeded 80%. Column experiments demonstrated that the SiPS-SO3Na could immobilize the lead cation efficiently at a high flow speed without leakage while the 732 resin was penetrated immediately. Besides, SiPS-SO3Na was also found possessing higher concentration rate and recovering rate in the dynamic enrichment of low-level lead. In summary, SiPS-SO3Na shows promise because of its extremely fast exchange kinetics, large exchange capacity, superb column compatibility, good renewable ability, and excellent chemical and dimensional stability.