Sun Jiangang, Yin Lipu, Huang Kai, Li Xiaohui, Ai Xianbin, Huang Ying, Yin Yanli, Liu Junyou
School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing Xueyuan Rd. 30, Haidian District 100083 Beijing City China
Institute of Bioresource, Jiang Xi Academy of Sciences Changdong Rd. 7777 Nanchang City Jiang Xi Province China
RSC Adv. 2018 Aug 7;8(50):28284-28292. doi: 10.1039/c8ra03502d.
Paddy field soil contaminated by cadmium may produce cadmium-containing corn due to the paddy's strong ability to accumulate cadmium. The washing of soil with an organic acid is one of the suitable technical choices for the remediation of cadmium-contaminated soils. The limiting factor of this method lies in the recycling and reuse of the huge amount of washing effluent in an efficient and economical way. In present study, the simulated solutions were used to examine the adsorption efficiency of cadmium on a biosorbent which was synthesized by using garlic peel as the raw material. The biosorption behavior of cadmium on garlic peel was systematically studied in the presence of a citrate ligand. Presented here for the first time, garlic peel with buoyant properties was carefully collected and used for the preparation of the adsorbent, and verified to have a prominent advantage in efficiently separating from the solution after adsorption because of its floatability. Results show that the presence of citrate has a significant inhibition effect on the adsorption behavior of cadmium on the floating garlic peel, at the optimal pH of 4.0, which can be ascribed to the competitive affinity to the cadmium from the citrate ligand. SEM shows that floating garlic peel has a ruffled epidermis in the flat surface and porous microstructure in the transversal surface, making it durable enough and favorable for adsorption; and -COOH was determined by FTIR to be the main functional group contributing to the adsorption capability of garlic peel. Cadmium can be eluted off the garlic peel after adsorption, and the garlic peel can be then reused for the next cycle of adsorption with little decrease in adsorption capacity, even after ten adsorption/desorption cycles. The real leach liquor of cadmium-contaminated soil sample by 0.01 mol L citric acid solution was used for testing, and it was found that after three adsorption uses, almost all the cadmium in the leach liquor had been recovered by the floating garlic peel. The above research results provided a possible route to recycle the soil washing solution by biosorption, giving a great perspective in the remediation of paddy field soil contaminated by cadmium.
受镉污染的稻田土壤可能会产出含镉玉米，因为水稻具有很强的镉积累能力。用有机酸冲洗土壤是修复镉污染土壤的合适技术选择之一。该方法的限制因素在于如何以高效且经济的方式对大量冲洗废水进行回收再利用。在本研究中，使用模拟溶液来考察镉在以蒜皮为原料合成的生物吸附剂上的吸附效率。在柠檬酸盐配体存在的情况下，系统研究了镉在蒜皮上的生物吸附行为。首次精心收集了具有漂浮特性的蒜皮用于制备吸附剂，并经证实因其漂浮性在吸附后能从溶液中高效分离方面具有显著优势。结果表明，在最佳pH值4.0时，柠檬酸盐的存在对镉在漂浮蒜皮上的吸附行为有显著抑制作用，这可归因于柠檬酸盐配体对镉的竞争亲和力。扫描电子显微镜显示，漂浮蒜皮在平面上有褶皱表皮，在横截面上有多孔微观结构，使其足够耐用且有利于吸附；傅里叶变换红外光谱确定羧基是对蒜皮吸附能力有贡献的主要官能团。镉在吸附后可从蒜皮上洗脱下来，蒜皮随后可用于下一轮吸附，即使经过十次吸附/解吸循环，吸附容量也几乎没有下降。用0.01 mol/L柠檬酸溶液对镉污染土壤样品的实际浸出液进行测试，发现经过三次吸附使用后，漂浮蒜皮几乎回收了浸出液中所有的镉。上述研究结果为通过生物吸附回收土壤冲洗液提供了一条可能途径，为镉污染稻田土壤的修复提供了广阔前景。
