Abstract
Poly-γ-glutamic acid and flocculants (PGAF) were prepared for the removal of phosphate ions from aqueous solution. Scanning electron microscopy images of PGAF were obtained, and the amounts of calcium and oxygen on the PGAF surface were confirmed by electron probe microanalysis. The removal percentage of phosphate ions by PGAF was 98.2% within 10 min. Hydroxyapatite (Ca10(PO4)6(OH)2) and calcite (calcium carbonate) were produced by adding PGAF to a phosphate ion solution. These products were collected using poly-γ-glutamic acid and precipitated in aqueous solution. The results suggest that the removal rate of phosphate ions is very fast, and solid/liquid separation is achieved very easily using PGAF. Moreover, the removal of phosphate ions by PGAF increased as the amount of adsorbent was increased. The optimal agitation speed for the removal of phosphate ions was 60 - 120 rpm, whereas the temperature and solution pH did not affect the removal of phosphate ions. Therefore, PGAF may be useful for the removal of phosphate ions from aqueous solution.
