Antibiofouling Performance by Polyethersulfone Membranes Cast with Oxidized Multiwalled Carbon Nanotubes and Arabic Gum

Abstract

Despite extensive research efforts focusing on tackling membrane biofouling, one of the biggest problems associated with membrane technology, there has been little headway in this area. This study presents novel polyethersulfone (PES) membranes synthesized via a phase inversion method at incremental loadings of functionalized oxidized multiwalled carbon nanotubes (OMWCNT) along with 1 wt. % arabic gum (AG). The synthesized OMWCNT were examined using scanning electron microscopy and transmission electron microscopy for morphological changes compared to the commercially obtained carbon nanotubes. Additionally energy-dispersive X-ray spectroscopy was carried out on the raw and OMWCNT materials, indicating an almost 2-fold increase in oxygen content in the latter sample. The cast PES/OMWCNT membranes were extensively characterized, and underwent a series of performance testing using bovine serum albumin solution for fouling tests and model Gram-positive (Bacillus subtilis) and Gram-negative (Escherichia coli) bacterial species for anti-biofouling experiments. Results indicated that the composite PES membranes, which incorporated the OMWCNT and AG, possessed significantly stronger hydrophilicity and negative surface charge as evidenced by water contact angle and zeta potential data, respectively, when compared to plain PES membranes. Furthermore atomic force microscopy analysis showed that the PES/OMWCNT membranes exhibited significantly lower surface roughness values. Together, these membrane surface features were held responsible for the anti-adhesive nature of the hybrid membranes seen during biofouling tests. Importantly, the prepared membranes were able to inhibit bacterial colonization upon incubation with both Gram-positive and Gram-negative bacterial suspensions. The PES/OMWCNT membranes also presented more resilient normalized flux values when compared to neat PES and commercial membrane samples during filtration of both bacterial suspensions and real treated sewage effluents. Taken together, the results of this study allude to OMWCNT and AG as promising additives, for incorporation into polymeric membranes to enhance biofouling resistance.

Microfiltration Membranes Modified with Silver Oxide by Plasma Treatment

“…As a result of this phenomenon, the filtration process efficiency decreases over time, the transmembrane pressure increases, and the membrane selectivity changes [3]. The formation of biofilm on the surface of filtration membranes is mainly caused by bacteria that constitute the majority of microorganisms present in the filtered media, which enable the absorption of other organic particles forming extracellular polymeric secretions [4]. The resulting biofilm leads to the accumulation of inorganic particles and forms an irreversible layer of sediment on the membrane surface.…”

Application of Waste Polymers as Basic Material for Ultrafiltration Membranes Preparation

“…A possible explanation is that the addition of nanocomposites slows down the solvent/anti-solvent exchange rate in the coagulation bath and this caused the formation of thinner membranes with a thicker skin layer due to the entrapment of more CNTs at the top surface during phase separation. These macrovoids and the developed finger-like structures enhance the permeation of water, thereby allowing for increased membrane flux [31]. Figure 8 presents the reduction degree of water quality parameters in ultrafiltration process with waste polystyrene membranes modified with carbon nanotubes.…”

Microfiltration Membranes Modified with Composition of Titanium Oxide and Silver Oxide by Magnetron Sputtering

“…This requires membranes to be cleaned or replaced more frequently leading to a reduction in filtration efficiency and an increase in filtration costs [3][4][5]. Membranes made from polymers in many cases can be easily exposed to biofouling [6]. Microbial biofilm can form in both cases: living or non-living surfaces and are prevalent in natural, industrial and hospital settings [7].…”