pH及络合剂对亚铁活化S_2O_8^(2-)氧化去除活性艳蓝的影响研究

Influences of pH and Complexing Agents on Degradation of Reactive Brilliant Blue KN-R by Ferrous Activated Persulfate

以蒽醌染料活性艳蓝KN-R为目标污染物,研究了pH及不同pH条件下络合剂对于络合的亚铁活化过硫酸钠氧化去除KN-R的影响,并对络合体系与未络合体系进行比较.结果表明,由于PS在酸性条件下降解速度最快及酸性条件下主导自由基SO4-.氧化还原电位大于碱性条件下的.OH,所以酸性条件下KN-R的去除率远大于中性及碱性条件.pH=3时,EDTA体系KN-R 3 h剩余率仅为17.0%,PS的消耗率最低为32.3%,EDTA是酸性条件下的最佳络合剂选择;pH=7时,EDTA、柠檬酸体系3 d后KN-R的剩余率分别为11.3%、12.4%,PS消耗率仅为28.9%、28.0%,是中性条件的最佳络合剂选择;pH=10时,葡萄糖酸、柠檬酸、EDTA、酒石酸体系对KN-R的去除率及PS的消耗率基本相同,均能充当亚铁离子的络合剂.微量的亚铁存在时,络合剂的加入能很好地提高污染物的去除率,3 d后从52.5%提高到79.3%,说明PS适合于污染物的原位化学氧化降解(ISCO).

The influences of pH and complexing agents on degradation of reactive brilliant blue KN-R by ferrous activated persulfate were investigated,and finally the complexed and the uncomplexed system were compared.Because the lower the pH the more quickly will be the dissociation of S2O2-8 to the SO-·4 and the ORP of the dominant radical SO-·4 in the acidic condition is higher than the dominant radical ·OH in the alkaline condition,KN-R degradation rates in acidic condition are far outweigh in the neutral and alkaline conditions.When pH value was 3,the residual rate of KN-R was 17.0% within 3 hours by EDTA system with the lowest PS consumption rate 32.3%,so EDTA was the best complexing agent choice in acidic condition.When pH value was 7,the residual rates of KN-R were 11.3%,12.4% within 3 days by EDTA,citric acid system with the PS residual rates 28.9%,28.0% respectively,so EDTA,citric acid were the better choices in the neutral condition.When pH value was 10,glucose acid,citric acid,EDTA and tartaric acid systems all had the similar KN-R degradation rates and PS residual rates,so all could acted as the complexing agents.when the system contained trace amounts of ferrous,the addition of complexing agent would greatly improve the degradation rate of pollutant,from original 52.5% to 79.3% of 3 d,so PS is suitable for in situ chemical oxidation（ISCO）.