Removal of Ca(II) and Mg(II) hardness by ion exchange resins and soda ash for seawater pretreatment to reduce scale formation in evaporators multi-stage flash desalination
Khedidja Dahmani, Djamal Eddine Kherroub, Ahmed Boucherdoud, Benaouda Bestanı
Abstract
ABSTRACT Softening pretreatment by removal of calcium and magnesium from seawater using cation exchange resins and soda ash was examined with the long term aim of reducing scale formation in multistage flash plants. Infrared spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy analyses were employed to characterize the resins before and after pretreatment to demonstrate the presence of Mg 2+ and Ca 2+ on the resin surface. The changes in the composition and properties of seawater were also assessed. The results of this study revealed that the pretreatment achieved by a mixture of ion exchange and soda ash was successfully removed of 75% total hardness and reducing the concentration of Ca 2+ and Mg 2+ to 5 and 200 mg L –1 , respectively.