凹凸棒石-稻秸复合材料的制备及其对污染土壤中镉钝化效果的研究

为提高凹凸棒石(ATP)在土壤重金属修复中的性能，以ATP和水稻秸秆(稻秸)为原料，通过厌氧发酵法制备了ATP占稻秸质量分别为25%(F-25)、50%(F-50)、75%(F-75)、100%(F-100)和125%(F-125)的ATP-稻秸复合材料，研究了复合材料对污染土壤镉(Cd)的钝化效果。通过扫描电镜(SEM)和傅立叶红外光谱(FTIR)对复合材料进行了表征，探讨了复合材料对土壤Cd的钝化机制。结果表明，复合材料减少了土壤可交换态、碳酸盐结合态及铁锰氧化物结合态Cd的含量，而增加了残渣态Cd的含量，其中，F-25分别使土壤可交换态、碳酸盐结合态及铁锰氧化物结合态的Cd含量减少了14.11%、5.95% 和10.66%，而残渣态增加了29.15%。3% 添加量的复合材料F-25或5% 添加量的复合材料F-50对土壤Cd的钝化效果较好，钝化率分别为59.88% 和62.50%。复合材料对土壤Cd的钝化率随着钝化时间的延长急剧增加，但15 d后，钝化率增加缓慢。综合考虑复合材料配比、修复材料添加量及钝化时间对土壤Cd钝化效果的影响并兼顾成本，在污染土壤Cd修复时，应优先考虑复合材料F-25并推荐3% 的添加量。

Preparation of Attapulgite-Rice Straw Composite and Its Effect on Passivation of Cd in Contaminated Soil

In order to improve the performance of attapulgite (ATP) in remediating heavy metal contaminated soil, the composites of ATP-rice straw, containing ATP of 25% (F-25), 50% (F-50), 75% (F-75), 100% (F-100) and 125% (F-125) in rice straw, respectively, were prepared by anaerobic fermentation, the passivation rates of ATP-rice straw composites on cadmium (Cd) contaminated soil were studied. ATP-rice straw composites were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR), and then the passivation mechanism was discussed. The results showed that the contents of exchangeable Cd, carbonate Cd and Fe/Mn oxide Cd in soil were reduced, while the content of residual Cd was increased under the condition of the composite materials. F-25 reduced the contents of exchangeable, carbonate and Fe/Mn oxide Cd by 14.11%, 5.95% and 10.66%, respectively, while residual Cd was increased by 29.15%. F-25 with 3% addition amount and F-50 with 5% addition amount had better passivation rate (59.88% and 62.50%, respectively). The passivation rate of composites was increased rapidly with passivation time, then increased slowly after 15 days. Considering the influence of ratio of ATP-rice straw composite, the addition amount of the composite and passivation time on passivation effect of soil Cd and their cost, the composite material F-25 is given priority and the addition amount of 3% is recommended in remediation of Cd-contaminated soil.