袁河新余市区段水中COD_(Mn)的测定与分析

Determination and Analysis of the COD_(Mn) Changes in Xinyu city's Main River

通过优选优化水中CODMn的测定方法与条件,得到了适合本地段水质测定的方法是酸性高锰酸钾法,其适宜的测定条件为：（1）样品处理应在采集后2h内加入硫酸调pH＜2,且尽快检测;必要时应保存在0～5℃冷藏,并在48 h内完成测定.（2）KMnO4标准溶液和Na2C2O4标准溶液的浓度应在0.0095m～0.105 mol/L内.（3）应在沸水浴中加热,加热时间应从水浴沸腾时计,并控制为30±1 min.（4）加入（1＋3）H2SO4的体积为水样体积的5％.（5）应调控K值为0.85～0.95.（6）滴定时,起滴温度应控制在85±3℃,滴定结束时,滴定体系温度不低于65℃.（7）滴定应在2±0.5 min内完成.（8）用光度滴定或电位滴定法确定终点.从测定结果可知袁河新余市区段水中CODMn值从2002年以来是呈总体逐年向好方向发展,但不同年份、不同取样点和不同季节下所测得的CODMn值绝大多数达不到GB 3838-2002的Ⅱ类水质标准,个别甚至为劣于V类的水;文章分析了导致此现状的原因,并对存在的问题提出了一些解决对策.

The method for the determination of CODMn in water and condition optimized, the method is suitable for the determination of local water is acidic Potassium Permanganate method, the optimum determination conditions are as follows： （1）sample treatment should be added to the sulfuric acid pH〈2 within 2 h after gathering, and detected as soon as possible; when necessary, should be maintained at 0-5 ℃, and determination in the completed within 48 h. （2）The concentration of KMnO4 standard solution and Na2C2O4 standard solution should be in 0.0095-0.0105 mol/L. （3）The heating should be carried out in a boiling water bath, （4）and the heating time should be water bath boiling timepiece. （5）and control was 30±1 min. The K value for the 0.85-0.95 control of stress. （6）The titration, the drop temperature should be controlled at 85±3 ℃, the end of titration, titration system temperature not lower than 65℃. （7）The titration should be completed in 2±0.5 min. （8）The endpoint is determined by spectrophotometric titration and potentiometric titration. Yuan River in Xinyu City area water CODM, value since 2002 is a general has good direction, but in different years, different seasons and different sampling points in the measured CODM, values most is not up to the GB 3838- 2002 class 11 water quality standards, individual or even worse than grade V water. Analysis of the causes of the present situation, and puts forward some countermeasures to solve the problems.