Solvent extraction based on aliphatic 1

3-diols is a promising technique for the recovery of boric acid from salt lake brine.In this work

two diols

2-ethyl-1

3-hexanediol(EHD)and 2-butyl-2-ethyl-1

3-propanediol(BEPD)

were selected as extractants and toluene was used as diluent.The effects of extractant concentration

pH of brine

initial boric acid concentration

magnesium chloride concentration

and temperature on the distribution coefficients of boric acid were systematically investigated.Distribution coefficients of boric acid up to 9.43 and 8.25 were obtained from the boric acid aqueous solutions with the initial concentration of 0.0185 mol稬-1 when using toluene containing 0.4 mol稬-1 EHD and BEPD

respectively

as organic phases at 303.15 K.Higher extractant concentration or lower pH is favorable to the extraction.However

the distribution coefficients decrease gradually with the increase of boric acid concentration and temperature.The extraction of boric acid with aliphatic 1

3-diols is an exothermic process.The salting-out effect of magnesium chloride enhances the extraction performance.