抗坏血酸和铁系还原剂修复铬污染土壤

通过投加抗坏血酸(C₆H₈O₆)或铁系还原剂(FeCl₂,(NH₄)₂Fe(SO₄)₂,FeS)对重庆某化工厂的Cr污染土壤进行修复。除FeS外,其余3种还原剂对土壤中Cr(Ⅵ)的还原率均达80%以上,稳定效率均超73%,且投加量为理论值3倍和4倍时的效果相差不大。C₆H₈O₆相比于铁系还原剂表现出更好的长期稳定性,4~30 d的Cr(Ⅵ)浸出质量浓度均低于《生活垃圾填埋场污染控制标准》(GB 16889—2008)中Cr(Ⅵ)的浸出限值(1.5 mg/L)。投加3倍理论值C₆H₈O₆的土壤在30 d时的Cr(Ⅵ)浸出质量浓度仅为0.83 mg/L,稳定效率高达98.3%。除FeS外,其余3种还原剂均显著增加了土壤中Cr的残渣态占比。FeCl₂和(NH₄)₂Fe(SO₄)₂会导致土壤pH降低。4种还原剂均未对土壤晶体结构产生明显影响。

Remediation of chromium-contaminated soil by ascorbic acid and iron reductants

Remediation of Cr-contaminated soil in a chemical plant in Chongqing was carried out using ascorbic acid (C₆H₈O₆) or iron reductants (FeCl₂,(NH₄)₂Fe(SO₄)₂,FeS). The reduction rate of Cr(Ⅵ) in the soil by the reductants,except FeS,was all over 80%,and the stabilization efficiency was all over 73%. The effects were not much different when the dosage was 3 times and 4 times of the theoretical value. Compared with iron reductants,C₆H₈O₆ exhibited better long-term stability. The leaching mass concentration of Cr(Ⅵ) at 4-30 d was lower than the Cr(Ⅵ) leaching limit (1.5 mg/L) in the national standard of GB 16889-2008. The leaching mass concentration of Cr(Ⅵ) in soil was only 0.83 mg/L at 30 d when C₆H₈O₆ with 3 times of theoretical value was added,and the stabilization efficiency was as high as 98.3%. The reductants,except FeS,significantly increased the proportion of Cr residual form in the soil. FeCl₂ and (NH₄)₂Fe(SO₄)₂ caused soil pH reduction. The 4 reductants had no obvious effect on crystal structure of the soil.