Investigation on effect of KCl addition on desalination performance of co-polymerized GO/Nylon nanocomposite membrane

[Display omitted] •Tuning the graphene interlayer spacing through simultaneous addition of KCl and polymerization.•First time investigation on effect of KCl on desalination performance of the copolymerized GO/Nylon nanocomposite membrane.•Preparation of a highly active membrane in desalination via forward osmosis. In this research work, following the efforts for providing fresh water for humans, a novel nanocomposite membrane was prepared. In this regard, potassium cation was added to co-polymerized graphene oxide (GO) to tune the interlayer spacing of the GO nanosheets. The prepared membranes were characterized by X-ray diffraction, contact angle measurement, Atomic Force Microscopy (AFM), and Field emission scanning electron microscopy (FE-SEM) equipped with Energy-dispersive X-ray spectroscopy (EDX). The XRD patterns confirmed that by adding potassium chloride (KCl) to GO containing membranes, interlayer spacing was optimized and led to presence of interlayer spacing in the range of 4–6 Å and 7.80 Å which are highly active in rejection of salt ions. To evaluate the desalination performance of the prepared nanocomposite membranes, forward osmosis (FO) process was considered. The results showed that although the membrane showed acceptable permeability, the salt rejection activity was enhanced considerably. The potassium cation containing membrane exhibited reverse salt rejection of 2.03 which was 6.31 in absence of it. This can be attributed to effect of potassium cations in optimizing and modifying interlayer spacing along with repulsion of Na+ due to charge similarity with K+.