Nano-biopolymer effect on forward osmosis performance of cellulosic membrane: High water flux and low reverse salt

Chitosan nano-biopolymers (CS-NPs) were synthesized, and nanocomposite membranes were prepared via phase inversion method. The synthesized CS-NPs and fabricated membranes were characterized using TEM, SEM, AFM, hydrophilicity analysis and porosity measurement techniques. Surface hydrophilicity and porosity of nanocomposite membranes considerably increased compared with pristine CA membrane, and structural parameter significantly decreased to 0.30-1.3 mm. Nanocomposite membranes presented superior forward osmosis (FO) performance by offering a high water flux and low reverse solute flux compared with CA so that optimum osmotic water flux reached 31.2 LMH, about four times higher than that of unmodified membrane. In this regard, reverse salt flux remarkably reduced from 2.33 gMH for pristine membrane to 0.09 gMH for nanocomposite membrane demonstrating efficacy of employed modification method in simultaneous improvement of both water and reverse salt flux. Nanocomposite membrane applicability was also investigated in desalination of seawater proving the satisfactory performance of membranes in FO.