PURIFICATION OF EGYPTIAN INDUSTRIAL GRADE PHOSPHORIC ACID TO THE FOODGRADE QUALITY VIA SOLVENT EXTRACTION TECHNIQUE USING A NEW HYDROPHILIC AND HYDROPHOBIC EXTRACTANTS

This paper describes the process of purification of Egyptian industrial grade phosphoric acid to the food grade quality through one step using methyl isobutyl ketone and ethyl alcohol as hydrophilic and hydrophobic extractants respectively. The optimum conditions achieved for one step extraction are phosphoric acid: ethanol: methyl isobutyl ketone ratio 1: 1: 7, room temperature, agitation time of 20 minutes and settling time of 5 minutes. Phosphoric acid (27% P2O5) at an O/A ratio of 1: 1 was used as a scrubbing agent in one stage, distilled water was used as a stripping agent, at room temperature, with O/A phase ratio 3: 1, settling time and agitation time of 5 minutes and 3 minutes respectively. The recovery of the extraction process achieved 99.7% The starting P2O5 concentration was 39.5% whereas its uranium value was 73.5 ppm. The obtained purified phosphoric acid contains 39.5% P2O5 depleted from uranium, and the obtained phosphoric acid is concentrated under reduced pressure to 85% P2O5.The quality of the obtained acid agrees well with that of the international food grade quality phosphoric acid. Finally a technological flow sheet was elucidated.