Immobilization of metals in contaminated soils using natural polymer-based stabilizers
Immobilization of metals in contaminated soils using natural polymer-based stabilizers
复制标题
使用天然聚合物稳定剂固定受污染土壤中的金属
DOI：
10.1016/j.envpol.2016.12.028
复制
发表时间：
2017
影响因子：
8.9
通讯作者：
Hu Yang
中科院分区：
文献类型：
--
作者：
Xue Tao;Aimin Li;Hu Yang
采用木质素（Ln）、羧甲基纤维素和海藻酸钠3种低成本天然高分子材料对采自南京某矿区的2个铅、镉污染土壤样品进行土壤改良。采用毒性特征浸出法（TCLP）和连续提取法评价了天然高分子的修复效果。稳定剂能降低污染土壤中Pb、Cd的生物有效性，显著降低了Pb、Cd的可交换态含量。TCLP结果表明，处理后土壤中Pb和Cd的淋溶浓度分别降低了5.46%~ 71.1%和4.25%~ 49.6%。两种金属的有机形态含量均随稳定剂用量的增加而增加，这是基于连续萃取金属形态的再分配。这些发现是由于这样一个事实，即丰富的含氧基团的聚合物的修改是有效的螯合和固定铅和镉，这已被进一步证实，从金属吸附在水溶液中。此外，由于Ln具有独特的三维分子结构，在所研究的三种聚合物中，Ln的固定效果最好，这也表明Ln对土壤中Pb的固定效果优于Cd。因此，上述天然聚合物在减少金属离子进入食物链方面具有很大的应用潜力。
Three low-cost natural polymer materials, namely, lignin (Ln), carboxymethyl cellulose, and sodium alginate, were used for soil amendment to immobilize lead and cadmium in two contaminated soil samples collected from a mining area in Nanjing, China. The remediation effects of the aforementioned natural polymers were evaluated by toxicity characteristic leaching procedure (TCLP) and sequential extractions. The stabilizers could lower the bioavailability of Pb and Cd in the contaminated soils, and the amount of the exchangeable forms of the aforementioned two metals were reduced evidently. TCLP results showed that the leaching concentrations of Pb and Cd were decreased by 5.46%–71.1% and 4.25%–49.6%, respectively, in the treated soils. The contents of the organic forms of the two metals both increased with the increase in stabilizer dose on the basis of the redistribution of metal forms by sequential extractions. These findings were due to the fact that the abundant oxygen-containing groups on the polymeric amendments were effective in chelating and immobilizing Pb and Cd, which have been further confirmed from the metal adsorptions in aqueous solutions. Moreover, Ln achieved the greatest effect among the three polymers under study because of the former's distinct three-dimensional molecular structure, showing the preferential immobilization of Pb over Cd in soils also. Thus, the above-mentioned natural polymers hold great application potentials for reducing metal ion entry into the food chain at a field scale.