Production and Performance Study of Forward Osmosis Membrane Using Cellulose Triacetate and Cellulose Acetate Combined with Polyethylene Terephthalate Mesh

Abstract

In this research, the forward osmosis membrane was produced by using cellulose triacetate (CTA) and cellulose acetate (CA) with polyethylene terephthalate (PET) nonwoven to enhance membrane performance. The preparation conditions including CTA/CA ratio, CTA/CA concentration, casting with PET and annealing time were tested for their effects on formation and performance of membranes. The performance of produced membranes was carried out with 2 filtration systems with dead-end and cross-flow which were employed for the investigation of the water flux, reverse salt flux and specific reverse salt flux. These membranes were tested under the same operating conditions both in the FO and PRO mode.For cross-flow filtration, the operating conditions including flow rate and fouling of optimized membrane were studied. The membrane structure and morphology has been elucidated with scanning electron microscopy (SEM). The result indicated that the produced CTA/CA membrane has a typical asymmetric three-layered structure with the large macrovoids and the nonwoven PET was well embedded in the membrane. The optimized membrane with CTA/CA ratio 1:3 under the concentration of CTA/CA 16wt.% has the available water flux and reverse salt flux in cross-flow filtration of 23.9 L/m².h and 13.6g/m².h, respectively. The high selectivity properties were observed with the relatively minimal specific reverse salt flux of 0.6g/L. The performance of the optimal membrane was tested using 1M NaCl draw solution and DI water as the feed solution which both side along with flow rate 520 mL/min in a counter current pattern. Moreover, the total resistance of the membrane in the PRO mode was higher than that in the FO mode