Polyethersulfone/multi-walled carbon nanotubes mixed matrix membranes for bovine serum albumin removal and biocompatibility studies

Abstract

Hemodialysis is a process of purifying the blood of a person whose kidneys are not working normally. The design of a sustainable and high performance hemodialysis membrane is of great demand to solve the existing issues and heighten the hemodialysis performance. Hence, the objective of this study is to fabricate polyethersulfone/multi-walled carbon nanotubes (PES/MWCNTs) mixed matrix membrane (MMM) and evaluate its potential as a hemodialysis membrane. Prior to MMM fabrication, MWCNTs were purified by acids mixture (H2SO4/HNO3; 3:1 v/v) through chemical oxidation to remove carbonaceous and metallic impurities. Subsequently, the oxidized MWCNTs were functionalized with citric acid monohydrate via polycondensation process to form poly (citric acid)-grafted- MWCNTs (PCA-g-MWCNTs). The MMMs comprised of 17.6 wt% PES, 4.8 wt% polyvinylpyrrolidone and 0-0.2 wt% MWCNTs were fabricated via dry-wet spinning technique. The MMMs were characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM) and contact angle goniometer. The MMMs biocompatibility were studied in terms of compliment activation, protein adsorption and blood coagulation time. For separation and antifouling studies, the MMMs were subjected to permeation test at the pressure of 0.7 bar using pure water and 500 ppm bovine serum albumin (BSA) solution as the feed solution to obtain pure water flux (PWF), BSA rejection and PWF recovery rate. The matched FTIR spectra obtained showed that the MWCNTs have been successfully incorporated in the MMM. Based on the microscopic analyses using SEM and AFM, MMM incorporated with PCA-g-MWCNTs possessed larger pores and smoother surface. Besides, the decrease in the MMM contact angle value showed that the surface hydrophilicity of the MMM has been improved. The biocompatibility test results showed that the MMM incorporated with PCA-g-MWCNTs displayed the least complement activation and protein adsorption while keeping a normal blood coagulation time, hence demonstrating modest interaction with blood. The permeation test results showed that MMM incorporated with PCA-g-MWCNTs has better PWF and BSA rejection (J= 95.36 Lm-2h-1; R= 95.2 %) as compared to the MMM added with oxidized MWCNTs (J= 56.15 Lm-2h-1; R= 93.7 %) where the optimum PCA-g- MWCNTs loading was 0.1 wt%. The MMM incorporated with 0.1 wt% PCA-g- MWCNTs also achieved the highest PWF recovery rate (81 %) and showed less fouling effect. The PES/MWCNTs MMM was successfully fabricated and showed good biocompatibility and enhanced separation performance hence secures the essential properties to serve as hemodialysis membrane.