工业废水中微量苯酚的交流示波极谱滴定

AC OSCILLOPOLAROGRAPHIC TITRATION OF MICRO AMOUNTS OF PHENOL IN INDUSTRIAL SEWAGE

工业废水中微量污染物苯酚用交流示波极谱滴定可简单而快速地测定。准确分取部分过滤后的试样在氯化钾底液中以苯胺作指示剂，在不断搅拌下用0．02000mol·L^-1氢氧化钾标准溶液滴定，用汞膜电极作指示电极，银汞电极为参比电极，苯胺的示波极谱图上出现切口时即为滴定终点。根据氢氧化钾标准溶液滴定的体积计算试样中苯酚的含量。此滴定至终点的溶液的pH值经预先试验测定为11．27，而6g·L^-1苯胺溶液1mL在氯化钾底液中当出现切口时的pH值为11．3。苯胺在此方法中的作用为指示剂，以其示波极谱图上出现切口指示滴定终点。此方法应用于废水样品分析，回收率在97．3％～104．0％之间。

Phenol as a pollutant in industrial sewage in micro amounts was determined simply and rapidly by the AC oscillopolarographic alkalimetry. An aliquot of the filtered sample was taken and titrated in a KC1 base sdution with 0. 020 00 mol . L^-1 KOH standard solution under constant stirring with phenylamine as indicator. Mercury film electrode was used as indicating electrode and Ag-Hg electrode as the reference electrode. The endzpoim of titration ,ms shown by the appearance of an incision on the oscillopolarogram of phenylamine. From the volume of KOH standard solution used in the titration, the amount of phenol was calculated. The pH value of the solution at the end point of titration of phenol with KOH was determined previously and found to be about 11.27, and the pH value of 1 mL of 6 g. L^-1 phenylamine in KC1 base solution was 11.3 when an incision appeared on the oscillopolarogran. Hence, 1 mL of 6 g . L^-1 phenylanaine solution was suitable to be used as an indicator in the titration. In its application to the analysis of sewage sample, recoveries found were in the range of 97. 3%--104. 0%.