利用差分光谱法研究硬度离子Ca^(2+)/Mg^(2+)对混凝剂铁盐与溶解性有机物络合的影响

Effect of hardness cations on the complexation between coagulant ferric ion and dissolved organic matter by differential UV-visible absorbance spectroscopy

硬度离子Ca^(2+)/Mg^(2+)在水体中广泛存在,而其对水处理混凝工艺去除溶解性有机物(DOM)的影响并不是很清楚,这主要是由于缺乏可用于表征混凝环境条件下DOM、混凝剂、硬度离子之间相互作用过程的方法。采用差分光谱法,定量表征在pH为7时Ca^(2+)或Mg^(2+)对混凝剂Fe^(3+)与DOM络合过程的影响。结果表明,Ca^(2+)或Mg^(2+)的存在会显著影响Fe^(3+)与DOM的络合过程,随着Ca^(2+)或Mg^(2+)的浓度增大,对Fe^(3+)与DOM络合产生的抑制越显著,尤其是Mg^(2+)。研究为深入认识混凝去除DOM的机理提供了新方法与新视角。

Hardness cations(Ca2+and Mg2+)are widely present in water,while their effects on the removal of dissolved organic matter(DOM)by coagulation in water treatment are unclear yet.This is partly due to the lack of methods to characterize the interaction among DOM,coagulants,and hardness cations under the conditions of coagulation.In this study,the differential UV-visible absorbance spectroscopy method was used to quantitively characterize the effect of hardness cations on the complexation between ferric ion and DOM at pH 7.It demonstrates that the presence of hardness cations could significantly affect the complexation between Fe3+and DOM,and the inhibition against their complexation was aggravated with the increase of the concentrations of Ca2+or Mg2+,especially for the latter cation.The results provide a new method to reveal the mechanism of coagulation,as well as the effect of hardness cations on it.