Abstract:

The selective adsorption performance of nanoscale humic acid based ion exchange composite resin for Ni²⁺/Cd²⁺ was investigated from multi-ionic co-existing system. On this basis, a novel resource recovery process for Ni/Cd wastewater, which included multi-column series, saturated adsorption and concentrated circulation, was developed. The micro-morphology, chemical structure, heat resistance, element composition change and pore size distribution of nanoscale humic acid based ion exchange composite resin were characterized by SEM, FTIR, TG-DTG, XPS and BET. The experimental results showed that the ion exchange composite resin had the advantage of fast adsorption rate [0.55—1.50 mg·(g·min)^-1], high exchange capacity(139 or 148 mg·g^-1 for Ni²⁺/Cd²⁺ on Ca²⁺ and Mg²⁺ coexisting system)and excellent selectivity behavior, high elution concentration and purity for Ni²⁺/Cd²⁺ (45.15 g·L^-1 or 39.17 g·L^-1, and Q_Ni(Ⅱ)/Q_total 0.989,Q_Cd(Ⅱ)/Q_total 0.994). After 200 adsorption-regeneration cycles, the physical and chemical structures of the adsorptive composite resin were still kept stable performance, and the section morphology and exchange capacity basically remain unchangeable, showing that it can be reused. The specific surface area, average pore diameter and pore volume were 1189.85 m²·g^-1, 30.2 nm and 0.96 cm³·g^-1, respectively with good thermal stability. The nitrogen content decreased from 16% to 12%, oxygen content increased from 26.49% to 29.96% and ionic exchange capacity rose from 5.38 mmol·g^-1 to 6.06 mmol·g^-1.

Key words: nanoscale humic acid based ion exchanger composite resin, nickel-cadmium containing wastewater, selective adsorption, multi-column series, saturated adsorption

摘要：

系统研究了纳米腐殖酸基离子交换复合树脂在多离子共存体系中对Ni²⁺/Cd²⁺的选择吸附性能。以此为基础,通过多柱串联、饱和吸附、洗脱液套用方法完成了对Ni²⁺、Cd²⁺冶金废水资源化治理研究,用扫描电镜(SEM)、红外光谱仪(FTIR)、热重分析仪(TG-DTA)、X射线光电子能谱仪(XPS)及N₂吸附-脱附分析仪(BET)等物理手段对复合树脂的微观形貌、化学结构、耐热性、元素组分变化及孔径分布进行表征。研究结果表明:纳米腐殖酸基复合树脂对Ni²⁺、Cd²⁺离子具有吸附速度快[0.55～1.50 mg·(g·min)^-1]、交换容量高(Ca²⁺、Mg²⁺共存体系中对Ni²⁺、Cd²⁺吸附容量分别为139 mg·g^-1和148 mg·g^-1)、选择性能好等优点,回收溶液中镍和镉离子浓度和纯度高(分别为45.15 g·L^-1和 39.17g·L^-1,且C_Ni(Ⅱ)/C_total 0.989,C_Cd(Ⅱ)/C_total 0.994);吸附-洗脱200次后,其物理、化学结构性能稳定;断面形貌变化不明显,交换容量基本不变,可重复使用;比表面积、平均孔径及孔容分别为1189.85 m²·g^-1、30.2 nm 和0.96 cm³·g^-1,热稳定性能好;氮含量从16%降至12%、氧含量由26.49%升至29.96%,交换容量由5.38mmol·g^-1升至6.06 mmol·g^-1。

关键词: 纳米腐殖酸基离子交换复合树脂, 镍/镉废水, 选择性吸附, 多柱串联, 饱和吸附