A Master of Science thesis in Chemical Engineering by Muhammad Qasim entitled, "Performance of Forward Osmosis Using Various Membranes," submitted in January 2013. Thesis advisor is Dr. Raafat Alnaizy and Co-Advisor Dr. Ahmad Aidan. Available are both soft and hard copies of the thesis.
As a result of water scarcity, increasing demand for freshwater, and energy intensive nature of the conventional desalination processes, advancing the science of desalination is crucial in the development of sustainable new technologies. With this in view, this research explores an energy-efficient desalination process, namely forward osmosis (FO). In this thesis, two FO apparatus were constructed for the desalination of brackish and seawater. The first apparatus consisted of a simple U-tube while the second apparatus used a submerged membrane to desalinate saline feed. The water flux performance of two commercial FO membranes was evaluated. The U-tube FO apparatus utilized a cellulose acetate membrane and magnesium sulfate (MgSO4) draw solution. Using 240,000 ppm of MgSO4 draw solution, the membrane achieved an average water flux of 4.06 L/m2 h and 0.60 L/m2 h in case of brackish and seawater feed, respectively. Pure product water with a salt content of 350 ppm was recovered from the diluted MgSO4 draw solution. On the other hand, the submerged membrane apparatus utilized a proprietary FO membrane and copper sulfate (CuSO4) draw solution. The copper sulfate draw solution was found to be suitable only for desalination of brackish water and an average water flux of 3.01 L/m2 h was observed using 200,000 ppm of CuSO4 draw solution. Pure water with 100 ppm of dissolved solids was recovered from the diluted CuSO4 draw solution. For the first time, metathesis precipitation reaction was used to recover pure product water from the diluted draw solution in the FO process. The magnesium sulfate or copper sulfate draw solution was reacted with stoichiometric amount of barium hydroxide to remove the soluble draw solute as a mixture of precipitates. The use of magnesium sulfate or copper sulfate as draw solute required no energy for product water recovery. Both the draw solutions were completely recovered at the end of the experiments for recycle and reuse in the FO process. Search Terms: Forward Osmosis; Desalination; Metathesis Precipitation; Magnesium sulfate; Copper Sulfate