Determination of sulphuric acid in process effluent streams using sequential injection titration

Sulphuric acid in process effluent streams from an electrorefining copper p lant was analysed with a sequential injection (SI) titration system using s odium hydroxide as titrant. In the proposed SI titration system a base titr ant, acid analyte and base titrant zone were injected sequentially into a d istilled water carrier stream in a holding coil and swept by flow reversal through a reaction coil to the detector. The base zones contained bromothym ol blue as indicator and the endpoint was monitored spectrophotometrically at 620 nm. The influence of carrier stream flow rate, acid and base zone vo lumes and titrant concentration on the linear range of the method was studi ed to obtain an optimum. A linear relationship between peak width and logar ithm of the acid concentration was obtained in the range 0.006-0.178 mol l( -1) of H2SO4 for a NaOH concentration of 0.002 mol l(-1). The results obtai ned for the SI titration of process samples were in good agreement with a s tandard potentiometric method with an RSD < 0.75% and a sample frequency of 23 samples h(-1). (C) 2000 Elsevier Science B.V. All rights reserved.