M. Nematzadeh - Chemical Engineering Department, University of Sistan and Baluchestan, Zahedan, I.R. Iran
A. Samimi - Chemical Engineering Department, University of Sistan and Baluchestan, Zahedan, I.R. Iran
S. Shokrollahzadeh - Chemical Technologies Department, Iranian Research Organization for Science and Technology, Tehran, I.R. Iran
A. Behzadmehr - Nanotechnology Reasearch Institute, University of Sistan and Baluchestan, Zahedan, I.R. Iran

Forward osmosis (FO) has recently drawn attention as a promising membrane based method for seawater and brackish water desalination. In this study, we focus on the use of calciun chloride (CaCl۲) and potassium bicarbonate (KHCO۳) as inorganic salt draw solution candidates due to their appropriate performance in water flux and reverse salt diffusion as well as reasonable cost. The experiments were carried at ۲۵ °C and cross-flow rate of ۳ L min−۱.  At the same osmotic pressure, the water flux of CaCl۲ draw solution tested against deionized feed water, showed ۲۰% higher permeation than KHCO۳, which it was attributed to the lower internal concentration polarization (ICP). The reverse diffusion of CaCl۲ was found higher than KHCO۳ solution which it would be related to the smaller ionic size and the higher permeation of this salt through the membrane. The water flux for both draw solutions against ۰.۳۳ M NaCl feed solution was about ۲.۸ times lower than deionized feed water because of ICP. Higher concentrations of draw solution is required for increasing the water permeation from saline water feed towards the draw side.

Calcium Chloride, Forward Osmosis, Inorganic Draw Solution, Potassium Bicarbonate