碘量法测废水中硫化物的改进

Improvement on Determination of Sulfide in Waste Water by Iodometry

对碘量法测定废水中硫化物的标准方法(HJ/T 60-2000)中所述条件做进一步优化试验,提出了如下改进:1选择水浴温度为65℃;2吹氮的气体流量及时间:第1次为80 mL·min-1和20min,第2次为300 mL·min-1和10 min,第3次为400 mL·min-1和6 min;3以1mol·L-1乙酸锌溶液为吸收液,当样品中硫化物的质量浓度≤1.5mg·L-1时,选择吸收液的加入量为3mL;4方法适用于硫化物质量浓度在0.4~3mg·L-1范围内的废水样品的分析;当实际质量浓度超过1.5mg·L-1时,应减少取样量,使实际测定的试液中硫化钠的质量浓度保持在1.5mg·L-1以内。按上述优化的条件,在实样的基础上作加标回收试验,测得回收率在94.4%~94.9%之间,测定值的相对标准偏差(n=6)在2.3%~3.4%之间。

Improvement on Determination of Sulfide in Waste Water by Iodometry ZENG Wen-chao1, SHAO Yong1, AN Li-chao1 , LIU Guang-dong2 （1. School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, China; 2. College of Chemical Engineering, China University of Petroleum （East China ）, Qingdao 266000, China） Abstract. Optimization for the conditions described in the standard method of iodometric determination of sulfides in waste water （HJ/T 60-2000） was made scrutinously, and the following modifications were given： （1） temperature of the water bath chosen： 65 ℃; （2） flow-rate and time of the 3 N2-blowings： 80 mL · min-1 and 20 min for the 1st blowing, 300 mL ·min-1 and 10 min for the 2nd blowing and 400 mL · min-1 and 6 rain for the 3rd blowing; （3） 1 mol · L^-1 zinc acetate solution was selected as absorbent, and 3 mL of the solution were used to absorb H2 S liberated from the sample solution containing 41.5 mg · L^-1 of sulfides; （4） the modified method was proved to be valid for samples containing sulfides in the range of 0. 4-3 mg · L^-1 and the portion of sample used for the determination should contain sulfides 41.5 mg· L^-1. On the base of waste water samples as matrixes, test for recovery of the proposed method was made by standard addition method, results of recovery found were in the range from 94. 4% to 94. 9%, with values of RSDs （n=6） ranged from 2.3% to 3.4%. Keywords： Iodometry; Sulfide; Determination; Waste water