Behavior of Phosphate Ion in Concentrating Process of Sea Water

Abstract

A study was conducted on the behavior of phosphate in the concentrating process of sea water. The behavior of phosphate was traced by using radioactive isotope, ³²P. Phosphate in sea water was spectrophotometrically determined by phosphomolybdate method after it was separated from other elements by coprecipitation with ferric hydroxide.
When the evaporating temperature was kept below 80°C, the loss of phosphate from the sample solution was negligible in the early stage of concentration. On the other hand, the phosphate transferred rapidly into the deposit, when more than 70% (in volume) of sea water was evaporated.
In the case of evaporation at temperatures more than 90°C, phosphate started to deposit in the early stage, but the precipitation rate was not so high as in the case mentioned above.
The depositing tendency of phosphate was more remarkable than that of strontium or calcium.