Sorption of aluminium on tri-n-butyl phosphate plasticized polyurethane foam sorbents from sodium hydroxide solution: application to the determination of aluminium in glasses and slags

Abstract

A method for the selective separation of aluminium from fluorine and phosphorus in NaOH solution based on tri-n-butyl phosphate (TBP)-plasticized polyurethane (polyethertype) foam, and the spectrophotometric determination of aluminium at pH ≈ 5.3 using Xylenol Orange are described. The parameters affecting the quantitative extraction of aluminium were optimized. The extraction was >99.5% in the range 0.20–0.30 mol l^–1 NaOH with an equilibration period of 90 min at 30 °C. Similarly, parameters affecting the elution or recovery of aluminium from the plasticized foam are also described; the recovery of aluminium was found to be >99.9% with 1 mol l^–1 HCl at 60 °C.

Aluminium was determined in the eluted solution at 530 nm as the aluminium–Xylenol Orange complex at pH ≈ 5.3 and 60 °C. Beer's law was obeyed up to 4 µg ml^–1 aluminium. Anions such as F^–, PO₄^3–, SiO₃^2–, VO₃^–, BO₃^3–, MnO₄^–, MoO₄^2– and GaO₂^– do not interfere with the method, which was standardized against National Bureau of Standards (now NIST) samples and applied to various glasses and slags.