Purification of Boric Acid by Ion Exchange Resin Adsorption

Ion exchange adsorption is an effective purification method,in which 732# strong basic cation exchange resin and 717# strong-acid anion exchange resin were choosed.As a result,the purity of boric acid by ion exchange process was successfully improved.Adopting mixed bed ion exchange,when the anion and cation resin volume ratio was changed from traditional 1∶1 to 3∶1,it was helpful for the anion adsorption.The effects of process parameters on the ion exchange,such as grain size of resin,solution concentration of boric acid,solution flow rate,height of resin bed and solution temperature were studied.The ion exchange process parameters were optimized,as a result,the best exchange absorption effect was reached.The experimental results indicated that,under the condition of room temperature,resin grain size of 100 mesh,boric acid solution concentration of 0.80 mol/L,exchange height more than 25 mm,exchange time of 40 min,solution flow rate at 8 mL /min,resin layer height of more than 800 mm could make the ion exchange fully completed.When the beginning leakage quantity was more than 96%,leakage point of resin exchange was 1.4 L.After ion exchange,the purity of boric acid could achieve 99.90% and the main content of impurities was Fe1.96×10-6,Cl-1.12×10-6,SO2-45.14×10-6,respectively.