紫外光激活过硫酸盐降解硫氰根研究

Degradation of Thiocyanate by UV Activiated Persulfate Process

为探明不同条件下的紫外光(UV)激活过硫酸盐(PS)降解硫氰根(SCN^-)的情况,在SCN^-质量浓度为100mg/L、温度30℃条件下分别研究了辐照度、pH、S_2O_8^(2-)含量对SCN^-降解效果的影响,并对反应产物和机理进行了分析。结果表明,SCN^-的降解率随光照强度的增大而增大,辐照度9.94 m W/cm^2时SCN^-降解率最大;随S_2O_8^(2-)含量的增加而增大,S_2O_8^(2-)浓度大于4 mmol/L后,SCN^-降解率变化缓慢;出水中残余的TOC含量随着S_2O_8^(2-)含量的增加而降低,S_2O_8^(2-)浓度4.5 mmol/L时最低;随着pH的增加SCN^-降解率在pH为5处达到最大;pH为11时出水中残余的CN^-的质量浓度为0.156 mg/L,达到GB 16171-2012排放标准。UV激活PS降解SCN^-过程中可能的反应历程为:硫元素首先被除去,转变成SO_4^(2-),而氮元素则主要转变为CN^-和NH_4^+-N。

The effects of light intensity, pH, and S2O82- contents on the degradation of thiocyanate （SCN-） were examined to understand the function of persulfate （PS） activated by the irradiation fi＇om ultraviolet （UV） light. The results showed that the degradation rate of SCN- increased with an increase in light intensity, and reached a maximum when light irradiance was 9.94 roW/era2. Whereas it increased with an increase of S2O82- content, and varied slightly when the concentration of S2O82- was bigger than 4 mmoFL. The residual TOC contents in effluent decreased with the increased of S2O82- content, and reached a minimum when SCN- was 4.5 mmol/L. The degradation rate of SCN- reached the maximum when pH was 5. However, the residual CN mass concentration was 0.156 mg/L when pH reached to 11, and it achieved emission standard of pollutants for coking chemical industry （GB 16171 - 2012）. In addition, we found that the sulfur element of SCN was converted into SO4 2- and the nitrogen element was transformed into CN- or NH4＋-N during the early period of reaction process.