Developing novel thin film composite membrane on a permeate spacer backing fabric for forward osmosis

•Thin film composite forward osmosis (FO) membranes with permeate spacer fabric were synthesized.•The water-soluble polymer (PVP) employed as paste on the back of the fabric.•Polymer penetration and thickness were controlled thanks to applied PVP.•PVP washed up during phase inversion in water bath. A repeatable method was introduced for developing liable flat sheet thin-film forward osmosis (FO) membranes on spacer backing fabric support. Pasting of a water-soluble polymer (Polyvinylpyrrolidone (PVP)) on the backside of the fabric was investigated to prevent the penetration of the polymer dope (Polyethersulfone (PES)) into the backing fabric during phase inversion. All samples were prepared on spacer fabric with a 250μm in thickness. First, PVP as a water-soluble polymer was cast in 100μm thickness on a glass plate and then the spacer fabric was pulled from the top on the pasted PVP to fill the bottom side of the fabric. The lower bottom side of the fabric was filled with PVP. This helped to limit PES polymer penetration and to achieve a thinner polymeric support layer during phase inversion. After interfacial polymerization and forming rejection, thin-film composite (TFC) FO membranes were obtained. Water flux of 17.1 Lm−2h−1 and reverse solute flux (RSF) of 9.2gm−2h−1 were achieved when 1M NaCl as draw solution and deionized water as feed solution (FS) were used under pressure retarded osmosis (PRO) operating mode for TFC2 sample.