| المستخلص: |
Membrane technology has been recognized as one of the most important technologies in water desalination. However, this technology is challenged by the fouling phenomenon, which causes higher operating pressure, flux decline, frequent replacement of membranes and eventually higher operating costs. Therefore, good antifouling membrane is needed for smooth operation. In this project, reverse osmosis membranes were synthesized and modified to enhance the fouling resistance with acceptable salt rejection and water flux. Interfacial polymerization of MPD and TMC was used for preparation of thin film composite membranes. Polysulfone ultrafiltration membranes were used as a support. The polyamide membranes were functionalized by Poly (ethylene imine) (PEI)/ poly (allylamine hydrochloride) (PAH) using spin assisted layer by layer technique. Box-Behnken design of experiment was used to study the effect of several parameters such as the number of layers, concentration of polyelectrolyte solution, and pH. Membrane characterization was performed using Atomic Force Microscope (AFM), Scanning Electron Microscopy (SEM), Fourier Transform Infra-Red (FTIR), Thermo Gravimetric Analysis (TGA) and contact angle. 50 bilayer modified membrane possess 15.8 L/m2.hr pure water flux with 98 % salt rejection; these values are close to pristine polyamide. However, after three hours of bovine serum albumin (BSA) filtration, it was observed that functionalized membranes managed to retain more than 88 % water flux as compared to pristine polyamide membrane which suffered from more than 42% flux drop. AFM and contact angle measurement showed that functionalized membranes have lower roughness and higher hydrophilicity that has enhanced the fouling resistance. Effect of number of layers, polyelectrolyte concentration, and pH was correlated with permeation performance and contact angle via statistical models derived from the design of experiment. An optimum preparation conditions were found and the predicted water flux is comparable with that of the pristine membrane while retaining higher salt rejection. In addition, it was found that the optimum membrane will resist fouling much more than the pristine membrane and the corresponding flux is 50% higher.
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