AC OSCILLOPOLAROGRAPHIC TITRATION OF MICRO AMOUNTS OF PHENOL IN INDUSTRIAL SEWAGE

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 KCl base solution 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 end-point of titration was 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 KCl base solution was 11.3 when an incision appeared on the oscillopolarogram.Hence,1 mL of 6 g·L-1 phenylamine 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%.