Removal of iron from industrial grade aluminum sulfate by primary amine extraction system

Abstract

The removal of iron from industrial aluminum sulfate by the primary amine extraction system composed of primary amine N-1923 as the extractant, n-octanol as the modifier and kerosene as the diluent was studied. The mechanism of removing iron by primary amine system was determined through slope analysis method and IR spectra. Also investigated were effects such as pH in aqueous phase, phase ratios O/A (organic/aqueous), the volume fractions of extractant and modifier in organic phase, and the contact time of extraction. At the same time, the research was conducted on stripping of iron using sodium chloride solution or sulfuric acid as stripping agents from the iron-loaded organic phase. The results showed 99.99% extraction of iron from industrial aluminum sulfate with the extraction system composed of 25 vol.% N-1923, 25 vol.% n-octanol and 50 vol.% kerosene when the phase ratio O/A was 1:2, pH value > 1.2 and contact time was 6 min. The difficulties in separating aqueous phase and organic phase were effectively overcome by n-octanol. The strip recovery of iron using 4.0 mol L − 1 sulfuric acid as the stripping agent was 96.5% which was slightly higher than that using 2.0 mol L − 1 sodium chloride.