Abstract
Solvent extraction has been known as an appropriate method to remove boron from wastewaters. Diols have been used most intensively for this purpose. In this study, equilibriums of boron extraction and stripping with a 1,3-diol was investigated at various boron and extractant concentrations, and pH values. From the distribution ratio of boron it was obvious that boron extraction was not affected by boron concentration, but it increased with the concentration of 2-butyl-2-ethyl-1,3-propanediol (BEPD), the extractant. In stripping, however, it was clear that the distribution ratio of boron decreased with boron concentration, and a stronger effect of BEPD concentration on stripping than on extraction was observed. From the data of the pH dependence of boron distribution ratio it clarified that boron extraction was intensive in acidic solution but in alkaline solution stripping of boron took place dominantly. The effect of K+ ion on boron stripping was also examined, and the result clarified that boron extractability increased with the concentration of K+ ion in the stripping phase even at high pH value as 12.5 to prevent stripping.
