• 关键词：氰化物  过硫酸盐  热活化  土壤修复  腐殖酸

• 基金项目：

• 魏云梅
• 重庆大学环境与生态学院，重庆 400044

• 陈莲英
• 重庆大学环境与生态学院，重庆 400044

• 任婷婷
• 重庆大学环境与生态学院，重庆 400044

• 李蕾
• 重庆大学环境与生态学院，重庆 400044

• 叶志洪
• 重庆大学环境与生态学院，重庆 400044

• 摘要：近年来，氰化物引发的环境问题日益受到关注，但相关研究较少.本文利用热活化过硫酸盐技术对水体和土壤中的氰化物的降解过程和机制进行了研究，以期为氰化物的去除提供依据.首先采用批式实验，探究了温度、过硫酸盐添加量和初始pH对水溶液中氰化物降解效果的影响，然后在水溶液氰化物降解实验基础上，采用模配土壤进行了土壤氰化物降解实验.水溶液氰化物降解实验的研究结果表明，过硫酸盐 添加量和温度对于氰化物的降解具有显著影响.当温度从25 ℃升高到70 ℃时，铁氰和亚铁氰的降解率分别从11.06%和17.66%升高到98.12%和97.94%.过硫酸盐添加量从0.5 g?L^-1提高至3 g?L^-1时，铁氰和亚铁氰的降解率分别从38.27%和35.82%升高到99.05%和99.66%.当 体系的初始pH值为4.5~9.0时，初始pH对于氰化物的降解影响并不明显，但当pH为强碱性时（如pH=12），氰化物的降解效果受到显著抑制.土壤氰化物降解实验的结果表明，当活化温度为60 ℃时，铁氰和亚铁氰的降解效率均随过硫酸盐增加而升高，最高降解率分别达46.88%和56.04%.与水溶液中氰化物的降解情况进行对比，发现土壤中氰化物的降解效率远低于水溶液体系.通过探究4种共存阴离子（包括Cl^-、CO₃^2-、H₂PO₄^-、腐殖酸）对氰化物降解过程的影响，发现腐殖酸对氰化物的降解呈现显著的抑制作用，且浓度越高抑制作用越明显，这可能是影响 土壤系统中氰化物降解效率重要原因.本研究通过自由基淬灭实验及氰化物降解产物分析试验证实热激发过硫酸盐产生的SO₄^.-和HO^.对氰化物降解起重要作用，将各种金属-氰络合物最终降解为NO₃^-和CO₂等终产物.

• Abstract：In recent years， environmental problems caused by improper disposal of cyanide contaminants have attracted increasing attention. However， only limited research works focus on cyanide elimination. This study explored the degradation effectiveness and mechanisms of two cyanide-bearing contaminants in water and soil by using thermal-activated persulfate technology. First， the effects of activation temperature， persulfate dosage， and initial pH on the degradation efficiency of ferricyanide and ferrocyanide in aqueous solution were evaluated by batch experiments. Based on the results of cyanide degradation in aqueous solution， the effectiveness of thermal-activated persulfate on cyanide degradation in the soil matrix was further assessed. The results from pure aqueous solution experiments revealed that persulfate dosage and temperature had significant effects on cyanide degradation. When the temperature increased from 25 ℃ to 70 ℃， the degradation rates of ferricyanide and ferrocyanide increased from 11.06% and 17.66% to 98.12% and 97.94%， respectively. When the amount of persulfate increased from 0.5 g?L^-1 to 3 g?L^-1， the degradation rates of ferricyanide and ferrocyanide increased from 38.27% and 35.82% to 99.05% and 99.66%， respectively. When the initial pH of the system was in the range of 4.5~9.0， the initial pH had no obvious effect on cyanide degradation， but when the pH was strongly alkaline （such as pH=12）， the degradation rate of cyanide was significantly inhibited. The results of soil cyanide degradation experiments showed that when the activation temperature was 60 ℃， the degradation efficiency of ferricyanide and ferrocyanide increased with the increase of persulfate dosage， and the highest degradation rates for the two cyanide contaminants were 46.88% and 56.04%， respectively. Compared with cyanide degradation rate in pure aqueous solution， the degradation efficiency of cyanide in the soil matrix was relatively lower at comparable experiment conditions. This study further explored the effect of four coexisting anions （including Cl^-、CO₃^2-、H₂PO₄^- and humic acid） on cyanide degradation， and the results disclosed that humic acid showed a significant inhibitory effect on cyanide removal. It was postulated that the presence of humic substances in the soil matrix was a major cause of its low cyanide removal efficiency. In combination of free radical quenching experiments and analysis of cyanide degradation products， this study proposed that persulfate radical （SO₄^.-） and hydroxyl radical （HO^.） generated by thermal-activated persulfate played an important role in cyanide degradation， and the metal-cyanide complexes can finally be degraded into final products such as NO₃^- and CO₂.

• Key words：cyanide  persulfate  thermal activation  soil remediation  humic acid

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