Highly permeable PVDF membrane with PS/ZnO nanocomposite incorporated for distillation process.

Ramin Roshani,Mohsen Jahanshahi,Majid Peyravi,Fatemeh Ardeshiri

doi:10.1039/c8ra02908c

Abstract

In order to enhance the flux and wetting resistance of PVDF membranes for MD applications, we have developed a novel PVDF blend nanocomposite membrane using a polystyrene/ZnO (PS/ZnO) hybrid nanocomposite. The PS/ZnO nanocomposite was synthesized by free radical polymerization of styrene in the presence of vinyltrimethoxysilane (VTMS) grafted on the surface of ZnO nanoparticles. The blend nanocomposite membrane is fabricated via the phase inversion method and we examined the effects of the PS/ZnO nanocomposite on porosity, mechanical properties, hydrophobicity, LEPw, morphology, surface roughness and MD performance. It was found that the addition of the PS/ZnO hybrid nanocomposite (0.25, 0.5 and 0.75%) resulted in an increase in porosity (>70%), which is attributed to increased pore size and reduction of the spongy layer thickness. Furthermore, the addition of the nanocomposite also improved the surface roughness and contact angle. Comparison between the neat and modified membrane shows that with incorporation of the PS/ZnO nanocomposite, the desalination flux of 30 g L−1 saline aqueous solution significantly increased and rejection reached 99.99%. Meanwhile, during 100 hours continuous desalination process, the membranes composed of 0.75% PS/ZnO hybrid nanocomposite exhibited high performance stability (15.79 kg m−2 h−1) compared with the neat PVDF membrane.

Highlights

Owing to its intrinsic advantages, such as low operating temperature, low hydrostatic pressure, low operating temperature, waste heat and renewable energy sources, and eventually low energy consumption, membrane distillation (MD) is considered as a preferred and practical approach to saline water desalination and is able to compete with pressure-based membrane processes.[1,2,3] from the commercial standpoint, this process has not been actualized yet in the industry, mainly owing to high operation costs, low ux and, most importantly, wetting phenomena.[4]
Nanocomposite membranes for MD application were successfully fabricated by loading different concentrations of PS/ZnO hybrid nanocomposite (0–0.75%) into the PVDF polymer matrix through phase inversion method
The PS/ZnO nanocomposite was synthesized via free radical polymerization of VTMS from vinyl groups gra ed on the ZnO

Summary

Introduction

Owing to its intrinsic advantages, such as low operating temperature, low hydrostatic pressure, low operating temperature, waste heat and renewable energy sources (solar or geothermal sources), and eventually low energy consumption, membrane distillation (MD) is considered as a preferred and practical approach to saline water desalination and is able to compete with pressure-based membrane processes.[1,2,3] from the commercial standpoint, this process has not been actualized yet in the industry, mainly owing to high operation costs, low ux and, most importantly, wetting phenomena.[4] MD is a thermal membrane separation process in which a hydrophobic microporous membrane acts as a barrier between the hot feed solution and cold distillate stream, across which the partial vapor pressure gradient creates a driving force to penetrate water vapor molecules from the feed to the permeate side.[5,6] In order to improve ux and prevent pore. Application of some of these approaches to fabricate superhydrophobic surfaces is restricted owing to high costs and complex operating conditions.[13,14,15]

Methods

Results

Conclusion