Complexometric Determination of Aluminium and Fluorine after Separation of Aluminium on TBP-Plasticized Polyurethane Foam

Abstract

Simple titrimetric methods have been described for determination of aluminium and fluorine after selective separation of aluminium from fluorine using TBP-plasticized polyurethane foam sorbents. The extraction of aluminium from 0.20 to 0.30M NaOH solution has been found to be quantitative at 25°C. The sorbed aluminium complex can be eluted with 1M HC1 and determined titrimetrically at pH ∼ 5.3 with EDTA by the back titration method using xylenol orange as indicator. Fluorine left in the aqueous part has been determined titrimetrically with standard thorium nitrate solution in presence of 40% acetone at pH 3.0 ± 0.2 using sodium alizarin sulphonate as indicator. Anions like—PO43-, SiO32-, AsO32-, VO3−, CrO42-, BO33-, MnO42-, MnO4− and GaO2−″ have no effect on the extraction of aluminium as well as on the determination of fluorine. Both the methods have been standardised against standard samples.