ABSTRACT
Ultrafiltration membrane technology holds promise for wastewater treatment, but its widespread application is hindered by fouling and flux reduction issues. One effective strategy for enhancing ultrafiltration membranes involves incorporating activated carbon powder. In this study, composite polyethersulfone (PES) ultrafiltration membranes were fabricated to include activated carbon powder concentrations between 0 and 1.5 wt.%, with carbon size fixed at 200 mesh. The ultrafiltration membranes were evaluated in terms of membrane morphology, hydrophilicity, pure water flux, equilibrium water content, porosity, average pore size, protein separation, and E-coli bacteria removal. It was found that the addition of activated carbon to PES membranes resulted in improvements in some key properties. By incorporating activated carbon powder, the hydrophilicity of PES membranes was enhanced, lowering the contact angle from 60° to 47.3° for composite membranes (1.0 wt.% of activated carbon) compared to the pristine PES membrane. Water flux tests showed that the 1.0 wt.% composite membrane yielded the highest flux, with an improvement of nearly double the initial value at 2 bar, without compromising bovine serum albumin rejection or bacterial removal capabilities. This study also found that the inclusion of activated carbon had a minor impact on the membrane's porosity and equilibrium water content. Overall, these insights will be beneficial in determining the optimal concentration of activated carbon powder for PES ultrafiltration membranes.
ABSTRACT
INTRODUCTION: The application of polyvinylidene fluoride (PVDF) as a filtration membrane is limited due to its hydrophobicity. This paper elaborated on the fabrication process of nanofiltration PVDF membrane incorporating various quantities of hydrophilic polyvinylpyrrolidone (PVP) and hydroxyapatite (HA) using a wet phase inversion method to improve its hydrophilicity. METHODS: The membrane was fabricated by using the wet phase inversion method. It was then characterized in terms of water permeability, water contact angle, water content, surface energy, and surface porosity. Bacteria and Fe ions filtration was conducted to investigate the membrane filtration performance. RESULTS: The PVDF/PVP/HA-blended membrane showed the highest water permeability (6,165 LMH/Bar), water content (45.2 %), and surface energy (104.1 mN/m) when 2 wt.% of PVP was introduced into the base polymer PVDF. This fabricated membrane, labeled as PVP 2.0, also showed the lowest contact angle (64°) and the highest surface porosity (42%). CONCLUSION: Overall, the PVP introduction patents into the polymeric membrane doping solution potentially improves membrane hydrophilicity and permeability.
ABSTRACT
The aim of this research was to study the possibility of using silver nanoflakes (SNFs) as an antibacterial agent in polysulfone (PSF) membranes. SNFs at different concentrations (0.1, 0.2, 0.3 and 0.4 wt.%) were added to a PSF membrane dope solution. To investigate the effect of SNFs on membrane performance and properties, the water contact angle, protein separation, average pore size and molecular weight cutoffs were measured, and water flux and antibacterial tests were conducted. The antimicrobial activities of the SNFs were investigated using Escherichia coli taken from river water. The results showed that PSF membranes blended with 0.1 wt.% SNFs have contact angles of 55°, which is less than that of the pristine PSF membrane (81°), exhibiting the highest pure water flux. Molecular weight cutoff values of the blended membranes indicated that the presence of SNFs does not lead to enlargement of the membrane pore size. The rejection of protein (egg albumin) was improved with the addition of 0.1 wt.% SNFs. The SNFs showed antimicrobial activity against Escherichia coli, where the killing rate was dependent on the SNF concentration in the membranes. The identified bacterial colonies that appeared on the membranes decreased with increasing SNF concentration. PSF membranes blended with SNF, to a great degree, possess quality performance across several indicators, showing great potential to be employed as water filtration membranes.
ABSTRACT
Polysulfone ultrafiltration membranes were fabricated using various sizes (20, 40, and 90-210 nm) of silver nanoparticles (nAg) blended in a dope solution. To characterize the performance and properties of the prepared membranes, scanning electron microscopy (SEM), water contact angle, protein separation, water flux, and antibacterial tests were conducted. The characterization results revealed that when nAg particles (20 nm) were blended into the base polymer PSF, the PSF/nAg blended membrane had the lowest contact angle (58.5°) and surface energy (110.7 mN/m). When experimenting with ultrafiltration using protein solutions, bare PSF and PSF/nAg-20 blended membranes gave similar values of protein rejection: 93% of bovine serum albumin (BSA) and 70% of lysozyme rejection. Furthermore, SEM studies showed that the surface pore size was reduced by adding 20 nm nAg particles in the casting solution. Most importantly, the introduction of 40 nm nAg particles reduced the growth of bacterial colonies on the membrane surface by up to 72%. These findings revealed that nAg particles are expected to be a potential modifier for the fabrication of an ultrafiltration membrane.
