S-NZVI/PS凝胶反应带修复硝基苯污染地下水

采用前置硫化法合成制备硫化纳米铁，研究其与过硫酸盐对硝基苯的联合降解效果，检测反应前后溶液中铁离子和TOC浓度变化，对反应前后的S-NZVI进行表征，分析S-NZVI和PS对NB的联合降解机制.以纳米硅胶溶液为胶结剂，以PS为活性成分，制备缓释PS溶胶，注入砂柱中扩散形成凝胶，与S-NZVI构成S-NZVI/PS组合反应带，研究其对模拟硝基苯污染地下水的原位修复效果.结果表明，S-NZVI能够高效去除NB并生成大量苯胺（AN），S-NZVI被PS氧化产生的Fe²⁺与PS组成活化过硫酸盐，对AN具有较好的降解和矿化效果.当NB浓度为100mg/L、S-NZVI和PS的投加量分别为0.5，2.5g/L时，NB去除率达91%，AN出水浓度为1.96mg/L，TOC去除率达64.09%.反应后S-NZVI的主要铁氧化产物为Fe₃O₄和FeO（OH）.反应带实验结果表明，S-NZVI/PS组合反应带可有效去除地下水的NB并高效消减NB还原产生的AN，当进水中NB浓度为100mg/L，流量为0.4mL/min，注入S-NZVI含量为1200mg/L的浆液200mL，二氧化硅含量为30%、PS含量为12.5%的PS凝胶4.8g时，S-NZVI/PS组合反应带7d内对AN的去除率最高达97.6%，NB当量累计去除率为83.7%.

Remediation of nitrobenzene contaminated groundwater by S-NZVI and persulfate gel reaction zone

Sulfidated-nanoscale zerovalent iron (S-NZVI) was prepared by pre-sulfide synthesis to study the degradation efficiency of nitrobenzene by S-NZVI and persulfate (PS). The degradation mechanism of reaction was investigated by detecting the change of iron ion concentration, TOC concentration and characterizing S-NZVI before and after the reaction. The S-NZVI/PS reaction zoon was established by injecting S-NZVI and gel which nano-silica solution was chosen as the binder and PS as the active components, to study the effect of in-situ remediation on simulated nitrobenzene contaminated groundwater. S-NZVI could effectively remove NB and generate a large amount of aniline (AN). The Fe²⁺ formed by PS oxidized S-NZVI and PS composition activate persulfate, which had a good degradation and mineralization effect on AN. When the concentration of NB was 100mg/L, the dosage of S-NZVI and PS was 0.5g/L and 2.5g/L respectively, the removal rate of NB was 91%, the effluent concentration of AN was 1.96mg/L, and the removal rate of TOC was 64.09%. The main iron oxidation products of S-NZVI after the reaction were Fe₃O₄ and FeO(OH). The results of reaction zone showed that the S-NZVI/PS reaction zone could effectively remove NB from groundwater and effectively remove AN produced by NB reduction. When the NB influent concentration was 100mg/L, the flow rate was 0.4mL, 1200mg/L 200mL of S-NZVI and 4.8g PS gel with 30% silica and12.5% PS was injected, the removal rate of AN was up to 97.6%and the cumulative removal rate of NB equivalent was 83.7%, within 7d.