废铁屑预处理被4-硝基苯胺污染的土壤

利用机械厂废弃铁屑和分析纯级铁粉对受4-硝基苯胺(PNA)污染土壤的修复进行了对比研究,探讨了土壤酸度和反应温度对还原效果的影响,并对反应时间、铁屑用量和土壤含水量3个影响因素进行了优化选择.实验结果表明,在1.5g含PNA浓度约为1.3×10-5mol/g的模拟污染土样中加入100mg铁屑或铁粉和0.5mL蒸馏水,在25℃下反应4h,PNA的还原率分别为99%和76%,产物均为苯二胺(PDA);铁粉仅在偏酸性土壤中对PNA有较高还原率,铁屑则在中性或弱碱性土壤中仍能保持较好的还原效果;反应温度的变化对还原效果影响不大;正交实验结果显示反应时间对PNA的还原效果影响最大,土壤含水量次之,铁屑用量影响最小。

Pretreatment of 4-nitroaniline in Soils by Iron Chips

Remediation of 4-nitroamiline(PNA) contaminated soils by waste iron chips or analytical zero-valent iron(ZVI) was studied. Experimental results indicated that PNA was effectively reduced to phenylenediamine(PDA) . At ambient temperature of 25℃ and pressure,1.5g contaminated soil samples with 1.3×10-5mol/g PNA and 100mg iron chips or ZVI and 0.5mL distilled water,after 4h of reaction,the reduction rate of PNA was 76% by ZVI and 99% by iron chips. Reduction efficiency of PNA was high only in acidic soil by ZVI,but was high not only in acidic soil but also in neutral and alkaline soil by iron chips. Treatment temperature had little effect on reduction rate of PNA by iron chips. Orthogonal experiment results showed that the factors which could be controlled in practice were especially useful in the reduction reaction,with reaction time as the greatest,and followed with distilled water and dose of iron chips.