抗坏血酸对水中亚氯酸盐的去除效能研究

Chlorite-removal Performance of Ascorbic Acid from Water

本文对抗坏血酸(AsA)去除水中亚氯酸盐(ClO-2)的性能及影响因素进行研究.通过单因素实验,考察了在模拟饮用水常规处理条件下pH、温度、AsA投加量和作用时间对ClO-2去除率的影响规律;通过考察AsA投加比例、测定ClO-2降解产物,初步探讨AsA去除ClO-2的机理;通过正交实验,对去除工艺条件进行优化.结果表明,pH≤5.5时,温度、AsA投加量和作用时间的增加有利于ClO-2的去除;pH>5.5时,ClO-2去除率随pH的增加而下降;AsA可将水中的ClO-2还原成Cl-而将其去除,约2mol的AsA可去除1mol的ClO-2;AsA去除ClO-2的最佳pH、温度、作用时间和AsA与ClO-2的质量比分别为:5.0、30℃、25min和5.5.该工艺条件下,水中ClO-2浓度为2—10mg/L时,其去除率可达98%以上.AsA自身无害,处理过程产生的二次污染物少,因此可作为有效去除饮用水中ClO-2的候选药剂.

The chlorite-removal performance of ascorbic acid （AsA） from water and influential tactors was studied. The effects of pH, temperature, AsA dosage, reaction time on chlorite removal were investigated through single factor experiments under the simulation conditions of conventional tap water treatment. The chlorite-removal mechanism by AsA was discussed preliminarily based on the determination of chlorite-degradation products and the comparison on the ratio of AsA dosage. The removal-process conditions were optimized through orthogonal experiments. The results showed that the increased of temperature, reaction time and AsA dosage were all favorable for chlorite removal when pH ≤ 5.5, and while pH 〉 5.5, the chlorite-removal rates decreased with the increase in pH. AsA could remove chlorite from water by reducing it to chloride ion, about 2mol of AsA were needed to remove lmol of chlorite. The optimal pH, temperature,reaction time, and mass ratio of AsA to chlorite were 5.0,30℃, 25min and 5.5, respectively,and the removal rates were more than 98% over the range of 2--10mg/L of chlorite concentration. Therefore, AsA can be a candidate of optional agent for effectively removing chlorite from water, since it is harmless and less secondary pollutions produce in the treatment process.