催化法测定废水中Cr(Ⅳ)含量

Determination of Chromium (Ⅳ) Content in Caste Waterby Catalytic Method

弱酸性体系(p H=6.0)及加热80℃的条件下,表面活性剂十二烷基硫酸钠(SDS)增敏Cr(Ⅳ)能加快过氧化氢氧化亚甲基蓝的褪色反应,当反应其他条件不变时,亚甲基蓝褪色速度与Cr(Ⅳ)的浓度成正比.本实验探讨了测定方法的优化条件,并用该方法测定了废水中Cr(Ⅳ)的含量.结果表明:当Cr(Ⅳ)物质的量浓度在0~5.438 85E-05 mol·L-1范围内遵守朗伯比尔定律,其线性回归方程A_(SDS660)=-8 712.5x(SDS)+0.574 4,RSD为0.0845%;平均回收率为96.28%;该方法具有较高灵敏度、准确度,操作简便,可用此方法可有效地测定废水中的Cr(Ⅳ)的含量.

In acidic conditions,the hydrogen peroxide can oxidize methylene blue and make its color fading,but the effect is not obvious. In the presence of solution（ p H = 6. 0） and under the condition of 80 ℃,using sodium dodecyl sulfate（ SDS） for chromium（Ⅳ） sensitization with hydrogen peroxide catalyzed oxidation catalytic effects of fading reaction of methylene blue,when other reaction conditions are the same,the fading speed of methylene blue is in direct proportional to the concentration of chromium（Ⅳ）. This experiment studied optimum reaction condition of the reaction,the method was determined the chromium（Ⅳ） content in waste water,and at the same time,the precision experiment and recovery experiment were made. The results indicate that when the amount of substance concentration of chromium（Ⅳ） is in the range of 0 ~ 5. 43885 E-05 mol·L^（-1）,it obeys Lambert-Beer law,equation of linear regression ASDS660 =-8712. 5 x（ SDS） ＋ 0. 5744 and precision test RSD is 0.0845%; the average recovery rate is 96. 28%,This method has high sensitivity,accuracy,easy operation,which can be used to effectively measure the chromium（Ⅳ） content in waste water.