STRIPPING OF H3PO4 FROM nC4 - n C7 ALCOHOLS LOADED WITH PHOSPHORIC ACID

Pure phosphoric acid is obtained for food purposes by reduction of the phosphate rocks in an electric furnace to obtain P2O5 by the dry method. However, this method consumes a lot of energy and so it is rather expensive. There has been an increased interest in the past few years in purifying commercial wet phosphoric acid to obtain a pure acid. Several methods were developed on the pilot plant or commercial scales but most of the works are still in the developmental stage. This paper studies stripping of H3PO4 from nC4 - nC7 alcohols loaded with phosphoric acid. The alcohol mainly used is n-heptanol. The effect of temperature and mixing time on distribution ratio were studied. The results show that the stripping increases by increasing the number of carbon atoms or the molecular weight of the n-alcohol and with n-C7 alcohol the stripping process has a higher efficiency. It was possible to obtain 85 \% yield of H3PO4 by one stripping stage at room temperature. The temperature has a slight negative influence on stripping. The stripping is enhanced by increasing the concentration of P2O5 in the loaded n-heptanol