g-C_(3)N_(4)/TiO_(2)复合催化剂对土壤中绝缘油的光催化降解研究

Photocatalytic degradation of insulating oil in soil by g-C_(3)N_(4)/TiO_(2) composite catalyst

利用尿素与TiO_(2)制备g-C_(3)N_(4)/TiO_(2)光催化复合材料,并进行表征分析。然后针对绝缘油污染土壤进行光催化降解实验,考察不同光源、降解时间、催化剂用量、绝缘油初始浓度以及含水量对土壤中绝缘油降解效果的影响。结果表明:g-C_(3)N_(4)/TiO_(2)催化剂复合效果较好,光催化降解对土壤中绝缘油污染有良好的去除效果,在汞灯照射下,使用TiO_(2)催化剂效果略好,40 h降解率达到41.77%,氙灯照射下整体催化效果要优于汞灯照射,尤其是使用g-C_(3)N_(4)/TiO_(2)催化剂,土壤中绝缘油去除率明显提高,40 h时降解率达到77.67%。光催化效果随着绝缘油初始浓度的提高而下降,绝缘油浓度由0.5%提升至2%时,去除率由85.27%降至59.09%;随着催化剂用量的增加,绝缘油的整体降解率均有不同程度提高,在实验初期表现尤为明显;土壤中初始含水率在光催化反应初期对土壤中绝缘油去除率具有负面影响,含水量越高去除率越低,而随着水分不断挥发,24 h后初始含水量对降解速率已无影响。

The g-C_(3)N_(4)/TiO_(2) photocatalytic composite was prepared by urea and TiO_(2),and the characterization analysis was carried out.Then,photocatalytic degradation experiments were carried out for insulating oil contaminated soil,and the effects of different light sources,degradation time,catalyst dosage,initial concentration of insulating oil and water content on the degradation effect of insulating oil in soil were investigated.The results show that:The combined effect of g-C_(3)N_(4)/TiO_(2) catalyst is better,and the photocatalytic degradation has a good removal effect on the pollution of insulation oil in the soil.Under the irradiation of mercury lamp,the effect of TiO_(2) catalyst is slightly better,and the degradation rate reaches 41.77%at 40 h.The overall catalytic effect of xenon lamp irradiation is better than that of mercury lamp irradiation,especially the use of g-C_(3)N_(4)/TiO_(2) catalyst.The removal rate of insulating oil in soil increased obviously,and the degradation rate reached 77.67%at 40 h.The photocatalytic effect decreased with the increase of the initial concentration of insulating oil.When the concentration of insulating oil increased from 0.5%to 2%,the removal rate decreased from 85.27%to 59.09%.With the increase of catalyst dosage,the overall degradation rate of insulating oil increased,especially in the initial stage of the experiment.The initial water content in the soil has a negative effect on the removal rate of insulating oil in the soil at the initial stage of photocatalytic reaction,and the higher the water content is,the lower the removal rate is.However,with the continuous evaporation of water,the initial water content has no effect on the degradation rate after 24 h.