(559f) Fouling in Thin Film Nanocomposite Membranes for Power Generation through Pressure Retarded Osmosis

In the 21^st century, human faces a lot of fundamental challenges: energy, water, and food must be made available in increasing amounts for the world’s growing population. The quest is open to the broadest exploitation of novel solutions that could turn soon into new, sustainable ways to guarantee the availability of such life-essential items. Osmotic energy (or salinity-gradient energy) is the energy released when water with different salinities is mixed, such as rivers and oceans. By employing a semipermeable membrane to control the mixing process, the osmotic pressure gradient energy can be generated in terms of electrical power via pressure retarded osmosis (PRO) without causing adverse environmental impacts. This work presents the fabrication of thin film nanocomposite (TFN) membranes which are customized to offer high flux in forward osmosis (FO) and high osmotic power in PRO. In this study, the TFN membrane was fabricated by forming a polyamide thin film on the polysulfone substrate through the interfacial polymerization process. One of the challenges in this process is the fouling of PRO membranes. Fouling is one of the major characteristics that results in the decline in the water flux of the membrane. The hydraulic pressure during PRO processes is less than RO processes so membranes that are used for PRO are less likely to foul. Experiments show that TFN membranes are more tolerant of fouling than TFC membranes because of the nanomaterials which has higher surface hydrophilicity. The structure of the membrane is a very significant characteristic that has an influence on fouling. Especially, the structure of porosity that is coherent to the thickness. Membrane adjustment plays a key role in the trend of fouling. Zeolite loading in the polyamide layer was in the range of 0.05-0.3 wt%. Field emission scanning electron microscope (FESEM) and atomic force spectroscopy (AFM) studies indicated that zeolite was successfully embedded in the polyamide layer of the membrane. The lowest contact angle was obtained at 61.08° when 0.1wt% of zeolite was used. Similarly, after the certain cleaning strategies the 0.1wt% zeolite modified membrane resulted in higher water flux in both RO (9.66 L/m²h) and FO (5.8 L/m²h) experiments. TFN membrane incorporated with zeolite exhibits power density of 1.73 W/m² and retains its desired resilience to foulants for osmotic power generation.