一种磁性固体螯合材料对农田土壤Cd的移除修复效果研究

通过室内模拟试验,开展了投加一种磁性固体螯合材料(Magnetic solid chelator,MSC)并进行磁选回收对农田土壤Cd的移除修复效果、MSC回收率及磁选物质螯合捕集Cd能力的研究。结果表明,投加0.4%~1.2%的MSC材料并进行磁选回收对总Cd和有效态Cd的去除率分别为15.91%~17.69%和33.33%~50.26%,而MSC的回收率在74.01%~94.33%之间,有随投加量增加而增加并逐渐趋于稳定的趋势;磁选物质(主要为MSC材料)螯合吸附的Cd含量在19.31~25.72 mg·kg~(-1)之间,在0.4%处理中最高,显著高于0.8%、1%和1.2%处理,有随MSC材料回收量的增加而降低的趋势。0.8%和1.2%投加量时磁选物质螯合捕集的Cd能较好地解释土壤被去除的那部分Cd。处理后水样中的Cd含量低于我国地表水环境质量标准(GB 3838—2002)中的Ⅰ类标准(0.001 mg·L~(-1)),不会成为新的污染源。因此,MSC材料对农田土壤Cd具有一定的移除修复效果,为农田土壤重金属修复提供了一种新方法。

Removal and Remediation Effects of Cd from Cadmium-contaminated Farmland Soils by A Magnetic Solid Chelator

In this paper, a simulated experiment was carried out to study the removal and remediation effects of Cd from cadmium-contaminated farmland soils by a magnetic solid chelator (MSC) at different application rates as well as its recovery rates and chelating capacity for Cd. The results showed that when the application rates of MSC materials was between 0.4%and 1.2%, the removal rate of total Cd and available Cd were 15.91%~17.69%and 33.33%~50.26%, respectively. And the MSC recovery rates were between 74.01%and 94.33%which increased with the increase of application rates of MSC and gradually tended to be stable. The content of Cd in recycled magnetic materials(mainly MSC)was between 19.31 mg·kg-1 to 25.72 mg·kg-1, reaching to the highest at the application rates of 0.4%which was significantly higher than those of 0.8%, 1%and 1.2%treatment. But the content of Cd in magnetic materials had the trend that decreased with the increase of the recovery amount of MSC. The amount of Cd chelated by magnetic materials was nearly equal to the removal amount of Cd from soil at the 0.8%and 1.2%treatments. Besides, the Cd concentration in water samples was lower thanⅠ-level standard issued by the surface water environment quality standard(GB 3838—2002), meaning that it would not be a new pollution source .Therefore, MSC does have some removal and remediation effects on soil Cd and will provide a new method for remediation of heavy metals in farmland soils.