纳米腐殖酸动态吸附废水中镉离子及其洗脱特性

Dynamic adsorption and de-sorption characteristics of wastewater containing cadmium ion on nanoscale humic acid

在静态法研究纳米腐殖酸吸附模拟含镉废水基础上搭建考察模拟含镉废水中镉离子在吸附剂上动态吸附及洗脱特性的吸附柱实验装置,考察镉离子溶液浓度、吸附(脱附)温度、共存离子和进料流速对穿透吸附量和饱和吸附量的影响,运用Thomas模型研究了纳米腐殖酸柱吸附过程动力学机理,测定了再生后纳米腐殖酸的穿透吸附量和饱和吸附量,结果表明:初始镉离子浓度150 mg·L^(-1)和流速10 ml·min^(-1)下,其饱和吸附量分别为426.3mg·g^(-1)和405.5 mg·g^(-1);Thomas模型所得饱和吸附量qem分别为364.1、436.1和441.9 mg·g^(-1);洗脱峰镉离子浓度分别为3.3、12.0和22.0 g·L^(-1);共存离子SO_4^(2-)浓度增加,纳米腐殖酸对镉离子的穿透吸附量和饱和吸附量降低;吸附和脱附均可常温工况进行。经30次吸附和再生后,穿透吸附量和饱和吸附量无明显降低。用红外光谱仪(FT-IR)、扫描电镜(SEM)及X射线能谱仪(EDS)对纳米腐殖酸吸附再生前、后性能进行表征,结果表明:纳米腐殖酸物化性能稳定,形貌基本无变化,尺度发生一定程度减小,表面及内部的氨基、羟基等对吸附镉离子均发挥有效作用,该材料可满足重复使用。

Based on the study of the absorption of simulated wastewater containing cadmium ion on nanoscale humic acid using static method, the adsorption column experimental device was set up to study the dynamic adsorption and elution characteristics of simulated wastewater containing cadmium ion, and the influence factors such as cadmium ion concentration, adsorption（de-sorption） temperatures, coexisting ions, feed rate on the breakthrough adsorption capacity and saturated adsorption capacity were investigated. The kinetic mechanism of column adsorption process on nanoscale humic acid was studied by using Thomas model, and the breakthrough adsorption capacity and saturated adsorption capacity of nanoscale humic acid after regeneration were determined. The results showed that the initial cadmium ion concentration was 150 mg·L^-1 and the feed rate was 10 ml·min^-1, the saturated adsorption capacity was 426.3 mg·g^-1 and 405.5 mg·g^-1, respectively. The saturated adsorption capacity in Thomas model was 364.1 mg·g^-1, 436.1 mg·g^-1 and 441.9 mg·g^-1, respectively. The cadmium ion concentration at eluting peak was 3.3 g·L^-1, 12.0 g·L^-1 and 22.0 g·L^-1, respectively. The concentration of co-existing ions SO4^2- was increased, and the breakthrough and saturated adsorption amount of nanoscale humic acids for cadmium ion was reduced. Adsorption and de-sorption temperature were conducted with normal temperature condition. After adsorption and regeneration for 30 times, the breakthrough adsorption capacity and saturated adsorption capacity did not significantly decrease. The performance of nanoscale humic acid before and after adsorption and regeneration was characterized by FT-IR, SEM and EDS, respectively. The results showed that nanoscale humic acid had good stability of physical and chemical performances, the morphology had no obvious change, the scale decreased slightly, both the amide and hydroxyl on the surface and in the internal played an effective role, and thus this material can be used repeatedly.