Abstract
The pressure retarded osmosis (PRO) process requires high performance, high flux, high rejection, and resistant membranes under harsh conditions. Since conventional phase-inversion membranes are insufficient to permit the required water flux, alternative membrane fabrication methods need to be developed. Many studies have recently been carried out to fabricate strong enough nanofiber PRO membranes resistant to higher pressure while providing high flux and high rejection rates. This work aims to fabricate tubular nanofiber PRO membranes by the electrospinning technique. In the study, cellulose nanocrystals (CNCs) were added to polyacrylonitrile (PAN) polymer solution to fabricate nanocomposite nanofiber PRO membranes. According to the scanning electron microscopy (SEM), FT-IR, dynamic mechanical analysis, porometer, and contact angle analysis results, it is concluded that PAN and CNCs provided a complete mixture, and the addition of CNCs increased the mechanical strength in the PAN membranes, which is the crucial phenomena in PRO applications. In this study, the newly fabricated membrane achieves a higher PRO water flux of 405.38 LMH using 1 M NaCl and a DI as feed water. The corresponding salt flux is found as 2.10 gMH, which is higher than our previous study. The selectivity of the reversed flux represented by the ratio of the water flux to the reversed salt flux (Jw/Js) was able to be kept as high as 193.03 L/g for PRO operation. As far as we know, the performance of the work-developed membrane in this study has shown better performance than all PRO membranes reported in the literature previously.Graphic abstract
Highlights
Fossil fuels have a variety of harmful environmental effects by the emission of various toxins such as sulfur oxides (SOx) and nitrogen oxides (NOx), VOCs and greenhouse gases (Zhu et al, 2010; Alami et al, 2020)
Thin film nanocomposite (TFN) cellulose nanocrystal (CNC) added pressure retarded osmosis (PRO) membranes were successfully fabricated with tailor-made electrospinning machine
During operation, fabricated PRO membranes fulfill the needs of higher pressures
Summary
Fossil fuels have a variety of harmful environmental effects by the emission of various toxins such as sulfur oxides (SOx) and nitrogen oxides (NOx), VOCs and greenhouse gases (Zhu et al, 2010; Alami et al, 2020). Osmosis results in a rise in the flow rate of the high pressure stream – as long as the osmotic pressure differential (Δπ= πD – πF) exceeds the difference in the applied absolute pressure (ΔP= PD – PF), where π and P are the osmotic and hydraulic pressure of the fluids, and D and F are the draw and feed streams, respectively This illustrates a classic optimization problem that is essential for the implementation of PRO units, in that higher applied pressure results in higher energy recovery per mole of solvent transfer, and at a lower rate of solvent transfer at steady state (Manzoor et al, 2020)
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