Purification of Phosphoric Acid by Solvent Extraction
磷酸的溶剂萃取法净化

A study of purification of Chinese WPA by solvent extraction was carried out. The effect of temperature on distribution coefficient was investigated and the mechanism of extraction was discussed. The experimental results show that n-butanol has the highest capacity to extract phosphoric acid. With the increase of temperature, the distribution coefficient is found to decrease slightly. The study of extraction mechanism indicates that phosphoric acid is extracted in the form of neutral molecules. Accordingly, other stronger acids such as HCl added to the initial solution will be beneficial to the recovery of phosphoric acid. The fact that the metal ions in WPA are not extracted into the solvent makes out that the solvent extraction is one of the best methods to purify WPA.