Treatment of rayon waste effluent for the removal of Zn and Ca using Indion BSR resin

Zinc is an important non-ferrous metal which finds application in different industries viz. electroplating, metal finishing, textile, galvanising etc. These industries generate effluents containing zinc during processing. The discharge of these effluents not only pollutes the environment but also affects health. In the present studies, an ion exchange process has been used to remove zinc and calcium from the synthetic and actual rayon waste effluent using chelating ion exchange resin, Indion BSR. Various parameters viz. contact time, pH of the solution, resin dose, kinetics of extraction, acid concentration for elution etc., have been studied for zinc recovery from the effluent. Extraction of zinc from the aqueous feed by Indion BSR was found to increase with increase in time, pH of the solution and resin dose. Total zinc loaded in the resin was found to be 91.0 mg Zn/g resin under the saturation loading from the aqueous feeds of 0.5 mg Zn/mL at pH 5.3. The data for adsorption of zinc were found to be fitted well for both the adsorption isotherm, the Lagmuir as well as the Freundlich and second-order-rate equations. The eluted solution could be used for recovery/recycling of zinc by electrolysis/crystallization after purification of the concentrated solution. The raffinate obtained after the recovery of zinc could be disposed safely without affecting the environment.