Forward Osmosis Membranes – A Review: Part II

Forward osmosis (FO) is a technical term describing the natural phenomenon of osmosis: the transport of water molecules across a semipermeable membrane by osmotic pressure from a feed solution (FS) to a draw solution (DS). The diluted DS is then reconcentrated to recycle the draw solutes as well as to produce purified water. As the driving force is only the osmotic pressure difference between two solutions, meaning that there is no need to apply an external energy, this results in low fouling propensity of membrane and minimization of irreversible cake forming, which are the main problems controverted by membrane applications, especially in biological treatment systems (e.g., FO membrane bioreactor (FO-MBR)). The purpose of the book chapter is to bring an overview on the FO membrane manufacturing, characterizing and application area at laboratory or full scales. This book chapter is published in two parts. In the second part, which appears here, characterization of mass transport in FO membranes, fouling mechanisms and foulants on FO membranes in naturally asymmetric structure and application areas of FO membranes in the literature are mentioned. Cutting-edge technologies on FO studies are comprehensively reviewed and following major and minor titles are stated truly on the new technologies

Protein mediated textile dye filtration using graphene oxide-polysulfone composite membranes

Here we report graphene oxide (GO) concentration dependent protein binding (BSA) and dye filtration (RO-16) capabilities of polysulfone-GO composite membranes under different pH conditions (2, 7 and 10). The membranes were fabricated with different GO concentrations (1, 2, 4 and 8% w/w) and were successfully characterized for their physical and chemical properties, as well as for their performance ability. The best BSA binding and dye rejection rates were observed with 2% GO membrane at pH = 10, which were 95% and 78.26% respectively, suggesting that 2% is the optimal concentration. Further, considering the fact that RO-16 dye is acidic friendly, contact time studies were carried out with 2% GO membranes at pH = 2 and pH = 10. It was observed that 2% GO-polysulfone membrane at pH = 2 shows the highest dye rejection rate of 87.4%, supporting the importance of contact time in filtration technology

High performance polyamide thin film composite (PA-TFC) desalination membranes modified by zwitterionic silanes

By: Ilter, Selda Erkoc; Sharabati, Jalal; Saffarimiandoab, Farzin; et al. Conference: 254th National Meeting and Exposition of the American-Chemical-Society (ACS) on Chemistry's Impact on the Global Economy Location: Washington, DC Date: AUG 20-24, 2017  Sponsor(s):  Volume: 254 Meeting Abstract: 57 Published: AUG 20 201

Thin-film composite nanofiltration membranes with high flux and dye rejection fabricated from disulfonated diamine monomer

Novel nanofiltration (NF) membranes with improved flux, dye rejection, high pH and temperature resistance were developed using a disulfonated diamine co-monomer, disodium-3-3'-disulfone-4-4'-dichlorodiphenylsulfone (S-DADPS). Thin film composite (TFC) NF membranes were fabricated on a porous polysulfonebased ultrafiltration support layer via the interfacial polymerization between trimesoyl chloride (TMC) in the organic phase and S-DADPS/piperazine (PIP) mixture in the aqueous phase. The effect of S-DADPS content was investigated on the structure and properties of fabricated TFC-NF membranes by varying the ratio between SDADPS and PIP from 0/100 to 100/0 (w/w). The chemical structure, surface properties and the morphology of TFC-NF membranes were characterized by Fourier Transform Infrared (FT-IR) spectroscopy, Scanning Electron Microscopy (SEM), optical profilometry, contact angle, and zeta potential measurements. Salt and dye rejection behaviors of fabricated TFC-NF membranes were evaluated using 2000 ppm MgSO4 and NaCl solutions and 100 ppm Setazol Red and Reactive Orange 16 dyes, respectively. Dyes were filtrated in acidic, neutral and alkaline conditions for pH resistance tests. The temperature resistance of membranes was evaluated using pure water and dye solutions at 15 degrees C, 25 degrees C, and 40 degrees C. Among all TFC-NF membranes fabricated by varying the S-DADPS/PIP ratio, the membrane with an 80/20 ratio of S-DADPS/PIP resulted in superior properties such as increased water flux without considerable salt and dye rejection loss compared to the neat TFC-NF membrane without S-DADPS. In addition, the variation of S-DADPS/PIP ratio was demonstrated as a powerful tool to tune the balance of flux, separation and rejection performance of NF membranes for custom purification purposes

Fabrication and characterization of temperature and pH resistant thin film nanocomposite membranes embedded with halloysite nanotubes for dye rejection

In this study, nanofiltration (NF) membranes with high pH and temperature resistance were fabricated by introducing halloysite nanotubes (HNTs) into the organic phase during the interfacial polymerization step. HNTs were dispersed in cyclohexane with the concentration 0% (TFNO), 0.02% (TFN0.02), 0.04% (TFN0.04) and 0.06% (TFN0.06) as w/v (%). Fabricated membranes were characterized by FT-IR spectroscopy, SEM and AFM analyses, optical profilometry, contact angle and zeta potential measurements. Filtration performance tests were conducted with 2000 ppm MgSO4 and NaCl solutions and 100 ppm of synthetic dye solutions (Setazol Red Reactive and Reactive Orange dyes), respectively. For pH -resistance tests, synthetic dyes were filtrated in acidic, neutral and base conditions (pH = 4-7-11) to measure changes in flux and rejection. The effect of the temperature of the feed stream on membranes were determined by the filtration of pure water and dye solutions at 15 degrees C, 25 degrees C and 40 degrees C. Among different membranes fabricated with varying HNTs content, TFN0.04 membrane showed increased water flux without considerable salt and dye rejection loss