Rapid Surface Modification of Ultrafiltration Membranes for Enhanced Antifouling Properties

Abstract

In this work, several ultrafiltration (UF) membranes with enhanced antifouling properties were fabricated using a rapid and green surface modification method that was based on the plasma-enhanced chemical vapor deposition (PECVD). Two types of hydrophilic monomers—acrylic acid (AA) and 2-hydroxyethyl methacrylate (HEMA) were, respectively, deposited on the surface of a commercial UF membrane and the effects of plasma deposition time (i.e., 15 s, 30 s, 60 s, and 90 s) on the surface properties of the membrane were investigated. The modified membranes were then subjected to filtration using 2000 mg/L pepsin and bovine serum albumin (BSA) solutions as feed. Microscopic and spectroscopic analyses confirmed the successful deposition of AA and HEMA on the membrane surface and the decrease in water contact angle with increasing plasma deposition time strongly indicated the increase in surface hydrophilicity due to the considerable enrichment of the hydrophilic segment of AA and HEMA on the membrane surface. However, a prolonged plasma deposition time (>15 s) should be avoided as it led to the formation of a thicker coating layer that significantly reduced the membrane pure water flux with no significant change in the solute rejection rate. Upon 15-s plasma deposition, the AA-modified membrane recorded the pepsin and BSA rejections of 83.9% and 97.5%, respectively, while the HEMA-modified membrane rejected at least 98.5% for both pepsin and BSA. Compared to the control membrane, the AA-modified and HEMA-modified membranes also showed a lower degree of flux decline and better flux recovery rate (>90%), suggesting that the membrane antifouling properties were improved and most of the fouling was reversible and could be removed via simple water cleaning process. We demonstrated in this work that the PECVD technique is a promising surface modification method that could be employed to rapidly improve membrane surface hydrophilicity (15 s) for the enhanced protein purification process without using any organic solvent during the plasma modification process.

Advances in surface modification and functionalization for tailoring the characteristics of thin films and membranes via chemical vapor deposition techniques

“…192 Figure 6 (c) exhibits the effect of deposition time on contact angle. In an investigation, Said et al 201 examined the effect of deposition time on membrane contact angle and the results showed a steady decline from 55 to 33 by raising deposition time from 15s to 90s, respectively. In fact, increasing the deposition time led to the concentration rise of the deposited material consisting of OH hydrophilic groups.…”

“…The influence of CVD deposition time on three key characteristics of the coating: (a) coating thickness, (b) pore size, and (c) surface contact angle 84,171,187,192,200,201,255 . [Color figure can be viewed at wileyonlinelibrary.com]…”

“…Khoo et al 187 explored the influence of the deposition time on hydrophilicity and demonstrated that it directly affected hydrophilicity of membranes and consequently the antifouling properties. WVTR [168] WVTR [192] OTR [168] OTR [192] Flux [84] Flux [201] Flux [201] Rejection [201] Rejection [201] Perm. [251] Perm.…”

Application of Cyclized Polyacrylonitrile for Ultrafiltration Membrane Fouling Mitigation

“…Membrane contaminants such as proteins, microorganisms, and colloidal solids can deposit on a membrane surface and block pores, which has an adverse effect on membrane performance as a result of reduced fluxes, changing membrane selectivity, increased operating costs, and shortened membrane life cycles [ 12 , 13 ]. Therefore, a highly relevant step is to modify UF membranes to overcome membrane fouling and enhance water fluxes [ 14 , 15 , 16 ]. Common methods include coating and grafting on the membrane surface [ 17 , 18 ].…”

Surface Modification of Stainless-Steel Membrane using a Closed-Batch iCVD Reactor for Oil/Water Separation

“…Moreover, CVD process can be easily scalable to achieve mass production using some equipment such as roll-to-roll process [15,16]. So far, various types of CVD techniques have been applied to functionalize different types of membranes [17][18][19][20][21][22].…”