Fabrication of a novel PVDF based silica coated multi-walled carbon nanotube embedded membrane with improved filtration performance

Abstract

In the present study, silica coated multi-walled carbon nanotubes (SiO2-CNT) were embedded into a pristine polyvinylidene fluoride (PVDF) polymer matrix to develop a novel PVDF/SiO2-CNT nanocomposite membrane. Initially, SiO2-CNT nanofillers were synthesized through sol gel method using commercial multi-walled carbon nanotubes (f-CNT) and incorporated into membrane matrix with varying loadings of 0.5%wt. and 1.0%wt. Pore former/polymer/solvent ratio was investigated to achieve the highest pure water flux and rejection in order to determine the most suitable pristine membrane recipe. Filtration performance properties such as flux, sodium alginate rejection, antifouling properties as well as the morphological characteristics such as porosity, pore size and distribution, hydrophilicity, surface roughness, functional groups, crystalline structure, thermal properties and mechanical strength of the SiO2-CNT embedded membranes fabricated with the best recipe were determined in comparison to those of pristine membrane. It has been demonstrated that incorporating hydrophilic SiO2-CNT into PVDF matrix increased the permeability from 303 to 377 L/m2h (25% increment) due to the improved dispersion of nanoparticles, which subsequently resulted in enhanced morphological properties. In addition to that, SA rejection of the pristine membrane increased from 84.5% to 90.2% and the flux recovery ratio increased from %74.2 to 94.7% with a comparatively smaller Rir value of 2.4 x 1010 m−1 by the addition of 0.5% SiO2-CNT nanofillers into the polymer matrix. Si-MWCNT impregnated nanocomposite membranes not only exhibited better filtration properties but also improved thermal stability and mechanical properties through the synergetic effect of nanotubes and silica group, which would provide in a significant increase in membrane life.