Removal of Selenium(VI) from Aqueous Solution with Polyamine‐type Weakly Basic Ion Exchange Resin

Abstract

The adsorption of selenium(VI) on the polyamine‐type weakly basic ion exchange resin (Eporasu K‐6) was studied by batch and column methods, for developing a process to remove selenium(VI) from waste water. Selenate ion (SeO4 2−) was very strongly adsorbed on the resin over a wide pH range 3 to 12. The adsorption of SeO4 2− on the resin followed a Langmuir type isotherm, and the saturation capacity and Langmuir constant were 1.7 mmol/g and 1.2×104 cm3/mmol, respectively. As a rise in concentration of sulfate ion (SO4 2−) in solution significantly reduced an adsorption ability for SeO4 2− · SeO4 2− in waste water must be removed by precipitating first as CaSO4 · 2H2O and then as very insoluble BaSO4 prior to use of the resin for removing SeO4 2−. Selenium(VI) adsorbed can easily be eluted from the resin with small volumes of 1 M HCl solution and the resin can be used repeatedly. The adsorption technique with the resin may be used for the final removal of selenium(VI) below the level of the limit of the industrial waste water regulation (0.1 mg/L) in the combination process based on the barium selenate precipitation technique.