Papers by Keyword: Membrane

Abstract: The increasing demand for clean water necessitates the development of advanced and cost-effective treatment technologies. Nanofiltration (NF) membranes offer high efficiency in removing divalent ions, but their application is often limited by membrane fouling and stability issues. While various polymer blends have been studied to address these limitations, the effect of incorporating chitosan (CS) into polyethylene glycol/cellulose acetate (PEG/CA) membranes for treating calcium-rich water remains underexplored. This study aimed to evaluate the impact of CS incorporation on the performance of PEG/CA NF membranes, specifically focusing on water flux and salt rejection in the removal of calcium carbonate from simulated groundwater. Membranes with 1–3 wt % CS were fabricated and compared to unmodified PEG/CA membranes. Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy confirmed CS presence, while Scanning Electron Microscopy (SEM) revealed morphological changes. Performance testing showed that the 1 % CS membrane had the highest water flux, whereas the 3 % CS membrane achieved the highest salt rejection. An inverse relationship between flux and rejection was observed with increasing CS content. Statistical analysis confirmed significant performance differences between modified and unmodified membranes. These results indicate that chitosan incorporation enhances NF membrane performance, offering a promising approach for improving water purification systems, particularly for hard water treatment.

Abstract: Recent interests in hybrid polymers for fuel cell applications have given rise to the exploration, modification, and application of various polymer ionomers. Polymer membranes doped with suitable fillers have improved fuel cell performance compared to the pristine polymers. In this study, three ionomers, PAN, PVP, and PVA were synthesised idividually and then functionalised with zirconium phosphate nanoparticles as membrane nanofillers. The nanofibers were synthesised using the sol-gel polymerisation method from their respective precursors dissolved in either water or DMF solution. This was followed by their subsequent fabrication through the incorporation of the zirconium phosphate nanoparticles, which were synthesised from their precursor salt using the precipitation method. Techniques such as SEM, FTIR, TGA, and XRD were employed to characterise the physiochemical properties of the synthesised polymers. In addition, the electrochemical properties of the synthesised polymers were evaluated using CV and EIS. The obtained results showed that conductive nanofibers were successfully synthesized. As the scan rates increased under cyclic voltammetry, the reduction peak for PVP voltammograms disappeared, and the PAN exhibited an irreversible redox system. It is also noticeable that when scan speeds increase, the oxidation peaks for PAN voltammograms shift to higher potentials. On the other hand, the TGA results indicated that these nanoparticles had excellent thermal stabilities, making them suitable for use in fuel cell membranes under tough conditions. Based on these findings, PAN, PVA, and PVP polymer materials can be used as filler (dopant) materials for fuel cell membranes.

Abstract: Membrane-based separation technology has grown significantly due to its cost-effectiveness, energy efficiency, easy system operations, and scale-up. The versatility of membrane application is also a significant factor in their widespread use in many separation processes. Their applications span water treatment, gas purification, energy production, and biomedicine. While promising, membrane technology still requires improvements in membrane features and performance, such as pore structure, fouling resistance, chemical stability, and concurrent enhancement of permeability and selectivity. Atomic Layer Deposition (ALD) has emerged as a powerful tool for enhancing membrane properties and performance through surface modification with atomic-scale precision, enabling conformal coatings, functional surface modification, and precise control over pore size. The ability of ALD to deposit uniform and conformal films on membrane substrates makes it a favourable modification technique. This review offers a concise yet informative discussion on the fundamentals of ALD, its integration with membrane modification, recent advancements in ALD-modified membranes, emerging trends in membrane modification via ALD, and challenges of ALD application in membrane modification.

Abstract: Enhancing ion transport through Metal-Organic-Framework (MOF) membranes is becoming increasingly important in various research fields, such as heavy metal separation from water, CO₂ absorption, and energy conversion. Using two-dimensional metal-organic framework (2D MOF) material has received tremendous attention in the salinity gradient power (SGP) and molecular separation due to its high surface area, tunable pore size, chemical stability, and flexibility. However, low ion flux is crucial yet challenging with standard 2D nanomaterial, due to limited pore, long ion path, and low ion selectivity. The insertion of nanofiber into 2D nanoporous Cu-TCPP membrane can generate interconnections between the interplanar nanofibers and the lamellar 2D nanoporous MOF membrane, introducing a fixed space‑charge density of –1.0×10⁷ C m⁻³ and resulting in increased mechanical strength, ion flux, and ion selectivity compared to the pure 2D MOF membrane. This study focuses on MOF/natural nanofiber membrane applied in converse energy from sustainable resource of seawater and river water. Regarding experiment, green and inexpensive natural-based fiber would be used to synthesize nanofiber (NNF) which are then compounded with 2D nanoporous Cu-TCPP to prepare Cu-TCPP@NNF nanofluidic membranes. The experimental results can be validated by means of COMSOL Multiphysics simulations based on the Poisson-Nernst-Planck and Navier-Stokes equations to indicate the effect of NNF on increasing space charge density and enhancing the ion transport through the membrane. Simulation results show that under a 500/10 mM NaCl gradient, the CuTCPP@NNF membrane delivers an opencircuit voltage (Voc) of 43.6 mV and a shortcircuit current (Isc) of 4.25 mA/m, which are 9% and 21% higher than those of the pristine CuTCPP film (40 mV, 3.5 mA/m). COMSOL simulations replicate experimental diffusion voltage within 1% of errors. These quantitative results demonstrate that NNF integration effectively elevates space charge, amplifies ion‑diffusion‑driven potentials and currents.

Abstract: Copper (II) is an essential heavy metal for living things and is beneficial for the environment if levels are still below permitted limits. Copper (II) levels in the environment can be determined using potentiometric sensors. The sensitivity in measuring the copper (II) potentiometric sensor greatly determines the analysis results. To increase the sensitivity of the potentiometric copper (II) sensor, AuNPs compounds were added to the composition of the membrane material based on S-Methyl N-(Methylcarbamoyloxy) Thioacetimidate or methomyl. In this research, the optimum composition of the membrane for making copper (II) potentiometric sensors based on methomyl has been determined and the effect of AuNPs compounds on the sensitivity of copper (II) potentiometric sensors based on methomyl has been studied. Research variables include the composition of the membrane used and variations in the addition of AuNPs compounds to the optimum membrane composition. The research results show the optimum performance of the copper (II) potentiometric sensor on the membrane composition methomyl: PVC: DOP with a ratio of 17: 17: 66 (%w/w) which produces a Nernst Factor value of 28.09 mV/decade. The addition of AuNPs compounds to the potentiometric copper (II) sensor membrane showed optimum performance when adding 0.1 mL of AuNPs with a Nernst Factor value of 29.55 mV/decade with a detection limit of 0.6 ppm copper (II). The addition of AuNPs compounds to the optimum membrane composition can increase the Nernst Factor value which is close to the theoretical Nernst Factor value.

Abstract: The most significant pollutant produced from agricultural industry in Kalimantan, Indonesia is Palm Oil Mill Effluent (POME). Due to the high levels of suspended particles and organic matter, POME has become a brownish color with high turbidity, color, chemical oxygen demand, and oil and grease content. To recycle the POME wastewater as clean water, these pollutants must be eliminated. In this study, we compare the effectiveness of hollow fiber (HF) and flat sheet (FS) membrane to remove total dissolved solid (TDS) and turbidity from POME with varied filtration pressure. HF and FS membrane were prepared from PVDF and nylon66 polymer, respectively. The PVDF HF membrane was modified using TiO₂ and SBE (spent bleaching earth) to improve HF membrane properties to maintaining fouling. Meanwhile, FS membrane was added by pectin to increase the hydrophilic properties. Overall membrane’s morphology was determined by Scanning Electron Microscopy (SEM) to investigate the membrane structure. Both of HF and FS membrane were operated via ultrafiltration (UF) under cross flow system. The filtration pressures were varied at 1-3 bar and followed by flux and rejection evaluation. The results show both HF and FS membranes has stability flux. In addition, TDS rejection up to 25% while turbidity is excellent high over 95% for all membranes. The fabrication HF membrane has finger like-sponge structure and FS membrane exhibits sponge asymmetric structure. Overall, all membranes perform highest water flux (FS membrane) while highest rejection conducted by HF membrane for POME wastewater treatment.

Abstract: Seawater desalination can be applied in Malaysia to overcome water supply issues which majorly due to water pollution. The desalination using membrane technology highly depends on the design of the membrane, operating conditions of the process, and the feed characteristics of the seawater. The aim of this research is to identify the effect of these factors on the performance of the reverse osmosis membrane in desalinating seawater in Malaysia. The simulation study is conducted by using the IMS Design program. The reverse osmosis (RO) membrane process that consists of three membrane stages arranged in series is designed accordingly. The effect of operating temperature, feed concentration, feed pH, and membrane stages on the salt rejection and permeate flux are evaluated. As a result, an increase in temperature and feed concentration reduces the salt rejection percentage, while increasing the permeate flux. However, there is no significant effect of feed pH on the salt rejection percentage and permeate flux since the type of membrane used is able to operate in a wide pH range. Lastly, the four stages membrane increases the permeate recovery and permeate flux but reduces the percentage of salt rejection.

Abstract: Zeolite filled polymer has recently emerged as a promising material with its immense applications. When taking water treatment into account, it is potentially an antibacterial film. In this study, poly vinyl alcohol (PVA)/chitosan/zeolite composite membranes were prepared with different proportions, including 5:1, 8:1 and 10:1 of PVA/chitosan ratios. Zeolite available in the film aimed to improve the morphology and the efficiency in water environment, with loading dosages of 10, 20 and 50 wt%, respectively. Characterization using scanning electron microscopy (SEM), SEM/EDX and X-ray diffraction (XRD) were also conducted to have a better view of the membranes. The results of antibacterial activity against aerobic bacteria using the 3M^TM Petrifilm^TM Aerobic Count (AC) Plate. The results indicated that pure chitosan film gave 75.7% of antibacterial activity and the composite film with 5:1 ratio of PVA/chitosan was the effective proportion, revealing the antibacterial rate around 53% to the applications of bacteria inhibition. The time test of antibacterial also reduced the level of bacteria in water environment to 2900 CFU of aerobic bacteria.

Abstract: Membranes are used in various different applications in water treatment due to the wide array of properties that can be attained from different materials and polymers. A new hybrid membrane for the purification of water by electrodialysis has been manufactured and studied in this research. The membrane consists of two different materials: A host polymer matrix and a cation selective metal organic framework, MOF. For the polymer matrix, polyvinylidene fluoride, PVDF, was selected to act as the body that is meant to be the backbone of the membrane. It was dissolved in different solvents with different concentrations to determine the most stable matrix. Using scanning electraon microscope, SEM, imaging, it was found that 10% wt in dimethylformamide (DMF) provided the most suitable conditions for this work. As for the cation selective MOF, UIO-66 was selected and then synthesized using hydrothermal method and characterized using X-ray diffraction, XRD, and found to match previous literature. UIO-66 provides the membrane with cation selectivity, which allows the membrane to function in an electrodialysis system, so it was dissolved with the PVDF matrix to provide a hybrid membrane. Different amounts of the MOF in the membrane matrix were tested to find the most suitable distribution of the MOF over the surface of the membrane and was found to be around 2%. The membrane was tested with LiCl salt, before and after UIO-66 addition, in a half cell to measure the influence of the UIO-66 as a cation selective material and its effect on ion migration.

Abstract: Zeolite have been widely used as gas separation material with its promising properties. One of gas separation technology available is using membrane composites because of its various benefits. A synthesis of membrane composites consists of zeolite/alginate then caried out to study the effect of the addition of Ethylene Glycol (EG) to the CH₄/CO₂ selectivity performance of the membrane. Membrane synthesis varied by its mass ratio of alginate:EG for 1:0, 1:0.25, 1:0.5, 1:1, and 1:2 and evaporated in the room temperature for 72 h. Characterization of the physico/chemical properties was done with various instruments such as FT-IR (Fourier Transform Infra-Red) Spectroscopy, Texture Analyzer, SEM (Scanning Electron Microscopy), and Permeation Test Cell Unit. Addition of EG into the membrane compositions proven to improve the separation performance showed by permeation rate improvement and selectivity value. Gas selectivity separations of CH₄/CO₂ was also investigated and it can be concluded that the synthesized membranes have several promising properties to be used as CH₄/CO₂ separations membranes.