用硅钨酸催化臭氧氧化降解聚乙烯醇模拟废水

以臭氧氧化不易生物降解的聚乙烯醇（PVA）模拟废水, 考察典型杂多酸（HPA）对臭氧氧化的催化作用. 先在3种典型杂多酸中筛选出对臭氧氧化PVA具有催化效果的硅钨酸（HSiW）, 考察反应时间、 臭氧质量浓度、 体系pH值、 催化剂用量和反应温度对PVA去除率的影响, 再通过正交实验确定去除PVA的最佳条件. 结果表明： 体系的pH值对PVA去除率影响最大, 催化剂用量的影响最小; HSiW催化臭氧氧化体系去除PVA的最佳条件为ρ(O₃)=25 mg/L， 反应温度30 ℃， 体系pH=8.3， 催化剂用量250 mg/L, 在该条件下降解反应5 min, PVA去除率即可达98.3%; HSiW未改变臭氧氧化降解PVA的基本途径, HSiW可促进臭氧分解, 生成更多的HO·, 并可催化臭氧与PVA的直接反应.

Degradation of Polyvinyl Alcohol Simulated Wastewater bySilicotungstic Acid Catalytic Ozonation

The catalytic effect of typical heteropolyacids (HPA) on ozonation was investigated by ozonation of polyvinyl alcohol (PVA) which was not easilybiodegradable. First, silicotungstic acid (HSiW) with catalytic effect on ozonation PVA was screened out among three typical heteropoly acids, and the effects of reaction time, ozone mass concentration, pH value of the system, catalyst dosage and reaction temperature on removal rate of PVA were investigated. Then, theoptimal conditions for removing PVA were determined by orthogonal experiments. The results show that the pH value of the system has the greatest influence on the removal rate of PVA, and the effect of catalyst dosage is small. The optimal conditions for the removal of PVA by the silicotungstic acid catalytic ozonation system are: ρ(O₃)=25 mg/L, reaction temperature of 30 ℃, pH=83, catalyst dosage of 250 mg/L. Under this condition, the degradation experiment was carried out for 5 m in, and the removal rate of PVA can reach 983%, the addition of silicotungstic acid does not change the basic pathway for ozonation to degrade PVA, the silicotungstic acid can promote ozone decomposition to generate more HO·, and can also catalyze the direct reaction between ozone and PVA.