| 某电镀厂六价铬污染土壤还原稳定化试剂筛选与过程监测 |
| 摘要点击 3222 全文点击 1284 投稿时间：2016-04-13 修订日期：2016-08-22 |
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| 中文关键词 重金属 六价铬 还原 稳定化 土壤修复 |
| 英文关键词 heavy metal hexavalent chromium reduction stabilization soil remediation |
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| 中文摘要 |
| 针对目前国内进行六价铬污染土壤修复过程关键性控制参数相对缺乏，且中长期稳定性效果相对较差等问题.选取北方某电镀厂六价铬污染严重的表层土壤，使用5组还原试剂进行还原稳定化试验，同时通过在线ORP（氧化还原电位）测试仪在线监测和定期取样测试，探索不同还原剂的反应效率和最终效果.其中试剂4对六价铬的还原稳定化率最高，基本上均在99.5%以上，六价铬浓度最低可达到2.4 mg·kg-1；从反应速率来看试剂1和4反应速率最快.反应过程的ORP、pH值监测数据也出现较大的区别，其中第1组土壤样品整个过程中ORP始终处于-400 mV左右；第4组反应在30 h以后，由-200 mV逐步升高并稳定在100 mV左右.从反应体系中的pH值变化情况来看，唯一使土壤pH保持在7左右的是试剂4.综合判断试剂4（多硫化钙和亚铁盐复配试剂）的综合还原效果最佳.以试剂4为基础进行单独放大试验，通过ORP和电导率两个关键参数的变化情况发现还原反应过程大概需要160 h，从而为后期实际土壤修复过程中控制还原土壤的养护条件和过程监控提供理论支撑. |
| 英文摘要 |
| There are lots of problems in the domestic remediation of Cr (Ⅵ) contaminated soil field,such as lack of the key processing parameters,poor long-term effect and so on.The Cr (Ⅵ) heavy polluted surface soil was sampled from an electroplating site in North-China,and then treated with five different reducing reagents.At the same time,the on-line ORP probes and interval sampling test were chosen to monitor the reaction process,and to explore the reaction rate and effect.The results showed that No.4 reagent had the highest Cr (Ⅵ) reduction effect,reaching up to 99.5%,and the minimum soil Cr (Ⅵ) concentration could reach 2.4 mg·kg-1.The No.1 and No.4 reagents had relatively faster reducing rates.There were obvious difference in ORP and pH monitoring values between different reductants,for example,the No.1 reagent kept the ORP value stable at around -400 mV.The No.4 reagent gradually increased the value from -200 mV to 100 mV since 30h,and then kept stable.According to the pH difference among different reductants,the No.4 reagent was the best and kept the pH value at around 7.Taking together the final effect and process key parameters,the No.4 reagent was the best.The scale-up experiment was operated with process monitoring,and the ORP and conductivity values showed that the reduction reaction took about 160 h.This work would provide theoretical basis for controlling the maintenance condition and reaction process in soil Cr (Ⅵ) remediation. |
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