该文探究了 UV与过碳酸钠(SPC)均相高级氧化体系去除酸性橙7(AO7)的反应机理.结果表明:当AO7初始浓度为20 mg/L、SPC投加量为0.5 mmol/L时,光解25 min时AO7去除率可达98.4％,反应过程符合一级反应动力学模型,R2＞0.990.当pH约为3.0时,25 min AO7去除率为74.2％,当pH值提高至10.0左右时,体系去除效率提升至99.8％.高浓度无机阴离子HCO3-和NO3-均会对体系产生抑制,低浓度Cl--轻微促进,而SO42-对反应速率几乎无影响.腐殖酸对AO7降解抑制相对较强,印染助剂柠檬酸钠对体系影响较小.自由基捕获实验和电子顺磁共振测试结果表明,UV/SPC体系中的活性物质为·OH、·CO3-、1O2和O2·-,·OH为主要活性自由基.TOC结果表明,60 min TOC去除率为41.8％,具有比UV/H2O2更好的矿化效果.UV-Vis吸收光谱分析表明,16 min左右时主特征峰接近完全消失.依据液相色谱-质谱联用仪实验结果提出了 AO7在UV/SPC高级氧化体系降解过程中的可能转化途径.
Study on the Mechanism of Degradation of Acid Orange 7 by UV/Sodium Percarbonate Advanced Oxidation System
The mechanism of removal of acid orange 7(AO7)by homogeneous advanced oxidation system of UV and sodi-um percarbonate(SPC)was investigated.The results showed that when the initial concentration of AO7 was 20 mg/L and the dosage of SPC was 0.5 mmol/L,the removal rate of AO7 could reach 98.4％after 25 min photolysation,and the reaction process was in line with the first-order reaction kinetic model with R2＞0.990.When pH=3.0,the removal rate of 25 min was 74.2％.When the pH value is increased to about 10.0,the removal efficiency of the system is increased to 99.8％.High concen-tration of inorganic anions HCO3-and NO3-can inhibit the system,and low concentration Cl-slight promotion.SO42-has little effect on the reaction rate.The results of free radical trapping experiment and electron paramagnetic resonance(EPR)test show that the active substances in UV/SPC system are OH,·CO3-,1O2 and O2·-,·OH is the main active free radical.The TOC results showed that the TOC removal rate of 60 min was 41.8％,which had better mineralization effect than UV/H2O2.The analysis of UV-Vis absorption spectra showed that the main characteristic peaks disappeared almost completely at about 16 min.Based on the experimental results of LC-MS,the possible transformation pathway of AO7 in the degradation process of UV/SPC advanced oxidation system was proposed.
sodium percarbonateacid orange 7UV/SPCadvanced chemical oxidation
万方数据
维普
