摘要
以果胶为原料,利用溶胶-凝胶法,Ca~(2+)为交联剂制备出果胶-Ca微球,使用多巴胺修饰果胶-Ca微球生成功能化的吸附剂果胶-聚多巴胺(PDA)微球。探讨了该吸附剂去除Th~(4+)的吸附性能,并利用SEM、FTIR和XPS分析了其功能化制备和吸附的机理。结果表明,果胶-PDA微球在pH=3.5时吸附效果最好,在25℃、pH=3.5、初始Th~(4+)质量浓度为24mg/L、吸附剂质量为0.03g的条件下,接触时间为1200min时,吸附容量可达到37.172mg/g;共存离子Cs+、Sr~(2+)、Mn~(2+)和Mg~(2+)对Th~(4+)的吸附影响较小,说明该吸附剂对Th~(4+)的吸附选择性较好;热力学和动力学研究结果表明,吸附过程符合线性Langmuir等温吸附模型和准二级动力学模型,最大吸附量为99.010 mg/g;热力学数据表明,果胶-PDA吸附Th~(4+)是一个自发吸热的过程;TG分析可知,果胶-PDA的热稳定性较改性前果胶-Ca有所提高;果胶-PDA上的N、O与溶液中Th~(4+)发生的螯合作用是果胶-PDA微球对Th~(4+)的主要吸附机理。
Pectin-Ca microspheres were prepared by sol-gel method with Ca~(2+) as cross-linking agent, and then dopamine was used to modify the pectin-Ca microspheres to prepare functional pectin-PDA microspheres as adsorbent. The adsorption performance of this adsorbent for removing Th~(4+) was discussed.SEM, FTIR and XPS techniques were used to analyze the preparation of pectin-PDA microspheres and its adsorption mechanism. The results showed that pectin-PDA microspheres had the best adsorption effect for Th~(4+) at pH=3.5. The adsorption capacity of adsorbent reached 37.172 mg/g under the conditions of 25 ℃,initial mass concentration of Th~(4+) 24 mg/L, adsorbent dosage 0.03 g, and contact time 1200 min.Co-existing ions Cs~+, Sr~(2+), Mn~(2+) and Mg~(2+) had little effect on the adsorption of Th~(4+), indicating that the adsorbent had better adsorption selectivity for Th~(4+). The thermodynamics and kinetics showed that the adsorption was described well by the Langmuir linear isotherm model and the kinetic data conformed to the pseudo-second-order kinetics model. The maximum adsorption capacity was 99.010 mg/g. The thermodynamic data showed that the adsorption of Th~(4+) by pectin-PDA was a spontaneous absorption. TG analysis revealed that the thermal stability of pectin-PDA microspheres was better than that of pectin-Ca microspheres. Coordination of N and O from pectin-PDA microspheres with Th~(4+) in solution was the main adsorption mechanism of pectin-PDA microspheres for Th~(4+).
引文
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