Boron recovery from clay waste using Diaion CRB-02 resin

A two-step process for boron recovery from clay waste is proposed in the present work. The leachate obtained after the clay waste was leached with sulphuric acid solution was treated with Diaion CRB-02 - a boron-specific resin for the separation of boron from the alkaline species in the leachate. The batch studies showed that a maximum boron recovery of about 95% was obtained at a pH value of 8.0, an initial boron concentration of 50 mg L(-1), a contact time of 24 h and a temperature of 25 degrees C. Equilibrium sorption data fitted the Langmuir isotherm. Column studies were carried out using different inlet boron concentrations and flow rates at a pH value of 8.0 and a temperature of 25 degrees C. The Yoon-Nelson and Thomas models were used to describe the dynamic behaviour of the column and to determine the column kinetic parameters. By these models and graphical integration, the column capacity values were found to be 7.3-8.5 mg g(-1) and 7.1-8.5 mg g(-1), respectively, and the 50% breakthrough time values were found to be 21-155 min and 19-149 min, respectively, depending on the inlet concentration and flow rate. It was observed that about 76% of the boron in the leachate solution could be recovered at an inlet boron concentration of 250 mg L(-1), a flow rate of 2.5 mL min(-1), a pH value of 8.0 and a temperature of 25 degrees C.