Eutrophication and water pollution caused by a high concentration of phosphate are two concerning issues that affect water quality worldwide. A novel cellulose-based adsorbent, cellulose acetate/graphene oxide/sodium dodecyl sulphate (CA/GO/SDS), was developed for water treatment. A 13% CA solution in a mixture of acetone:dimethylacetamide (2:1) has been electrospun and complexed with a GO/SDS solution. The field emission scanning electron microscope (FESEM) showed that the CA membrane was pure white, while the CA/GO/SDS membrane was not as white as CA and its colour became darker as the GO content increased. The process of phosphate removal from the solutions was found to be aided by the hydroxyl groups on the surface of the CA modified with GO/SDS, as shown by infrared spectroscopy. An optimization condition for the adsorption process was studied by varying pH, immersion time, and the mass of the membrane. The experimental results from phosphate adsorption showed that CA/GO/SDS had an excellent pH adaptability, with an optimum pH of 7, and maximum removal (>87.0%) was observed with a membrane mass of 0.05 g at an initial concentration of 25 mg L⁻¹. A kinetic study revealed that 180 min of contact time could adsorb about 87.2% of phosphate onto the CA/GO/SDS membrane. A typical pseudo-second-order kinetic model successfully portrayed the kinetic sorption of phosphate, and the adsorption equilibrium data were well-correlated with the Langmuir adsorption model, suggesting the monolayer coverage of adsorbed molecules.

Water pollution causes flora and fauna to be destroyed and this process might be irreversible as well as lead to other bad consequences, especially towards human beings. Due to the inefficiencies of the dyeing process, it is estimated that up to 200,000 tonnes of dyes are released into wastewater annually by the textile industry. This research aimed to fabricate the mixed matrix membranes made up of eggshells that were combined with silica (SiO2) for dye removal of Remazol Brilliant Blue R (RBBR). Poly ether sulfone (PES) and N-methyl-pyro-lidone (NMP) will be added in the formulation as a binder and solvent, respectively. The results from the characterisation and filtration process of the ceramic membrane with different ratios of eggshells and silica for removing Remazol Brilliant Blue R (RBBR) dye were compared. The ATR-FTIR showed a strong existence of carbonate minerals and silica proving its functional group and properties of having good capacity in filtration. The water contact angle measurement of the 4:1 ratio of eggshell: silica gave a low contact angle value which is 2.16o while the contact angle for a 1:1 ratio membrane is 1.99o, thus, the synthesis of the membrane was successful. From the filtration process, it was discovered that the 4:1 ratio of eggshell: silica was able to remove the 50 ppm blue dye with a removal efficiency of 81.39% compared to the 1:1 ratio with a removal efficiency of 76.17%. The adsorption capacity or the amount of dye adsorbed onto hollow fibre membrane and flat sheet membrane were found to be 1.423mg/g with an adsorption percentage of 71.15% and 1.616mg/g with an adsorption percentage of 80.80% respectively. To sum up, eggshells are a practical way to remove RBBR dye from a solution and a potential raw material for membrane manufacturing.

Fly ash generation is a continuously growing waste or by-product resulting from the combustion of coal, which is potentially to explore for membrane materials. The addition of hematite as an antifouling agent allows for the utilization of fly ash as a geopolymer-based membrane. The objective of this study is to create a hematite/geopolymer membrane utilizing type C fly ash by the direct foaming technique in order to enhance the porosity of the membrane. A homogeneous mixture was obtained by combining 65 grams of fly ash and 0.85 grams of Al(OH)3 with a base activator. Subsequently, 3 grams of hematite were added to the mixture. Subsequently, hydrogen peroxide (H2O2) was added as a foaming agent and gradually blended with different percentages of 0, 2, 4, and 6 weight percent (wt.%) into the paste mixture. The paste mixture was put into the mould and left to undergo the process of curing for a duration of 7 days. The fly ash was analysed using X-ray fluorescence (XRF), X-ray diffraction (XRD), and particle size analysis. Next, the membrane composite underwent characterization using XRD, FTIR, scanning electron microscope (SEM), and Archimedes techniques. The findings indicated that the fly ash from Pulang Pisau's Power Plant was officially identified and categorized as type C class. The diffractogram revealed the presence of mullite, quartz, and hematite phases in the hematite/geopolymer membrane. This finding was further verified by the FTIR analysis, which detected molecular vibrations indicating the existence of the T-O-T (T= Si or Al) and O-H components of the geopolymer structure. The scanning electron microscope images reveal that the membrane surface exhibits a rough texture and contains a limited number of microcracks resulting from the direct foaming process. Additionally, the measurements of porosity indicate that the porosity of the membrane increases proportionally with increased concentrations of H2O2. This research demonstrates the potential of coal fly ash as a sustainable raw material for developing advanced membranes for wastewater treatment.

Rapid industrialization and urbanization in this era have leads to water pollution and worsen the water scarcity. In this study, a modified poly(vinylidene fluoride) (PVDF) membrane was used to remove zinc and cadmium ions from solutions with concentrations of 10 ppm and 50 ppm, respectively. The hydrophobic PVDF support membrane was modified by a Layer-by-Layer (LbL) deposition technique with polycation, chitosan, and polyanion, poly(styrene sulfonate) to increase its hydrophilicity and metal ions rejection percentage as well as decreasing membrane fouling. Chitosan's hydroxyl and amine groups created an electrostatic interaction with the sulfonate group of poly(styrene sulfonate).The polyelectrolyte-modified membranes were characterized by using infrared spectroscopy and water contact angle measurements. The membrane filtering experiments revealed that the 5, 6, 9, and 10 layers of polyelectrolytes deposited membranes retained zinc/ and cadmium ions well, demonstrating the practicality of polyelectrolytes deposition on organic membranes because all rejection percentages were greater than 25%. The robustness of modified membranes was also tested by repeating 10 consecutive filtrations with the same membrane, and it was demonstrated that the modified membrane still had a higher rejection percentage that was two times higher and was less likely to foul due to less decreasing trends in permeate flux when compared to the unmodified membrane. It is expected that electrostatic repulsion and attraction as well as the steric effect were the primary mechanisms by which the modified membrane removed metal ions from contaminated solution.

Phosphate ion removal in wastewater via nanofiltration is a major challenge in wastewater treatment. In this study, cellulose acetate (CA) incorporated with graphene oxide/ sodium dodecyl sulphate (GO/SDS) and poly(allylamine hydrochloride)/poly(styrene sulfonate) (PAH/PSS) were synthesized using the electrospinning method. The membranes were characterized using attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), water contact angle, and field emission scanning electron microscope (FESEM). In addition, a multi-layered electrospun cellulose membrane was stacked using a layer-by-layer (LbL) technique to produce a functional ultra-filtration membrane for enhanced phosphate ions removal. The results showed that the modified membranes had better hydrophilicity and lower flux rates as compared to the unmodified membrane. The incorporation of compressed multi-layered for both unmodified and modified membranes also indicated increased phosphate ions removal efficiency up to 18.99 % and 43.08 %, respectively. In addition, post-filtration revealed that phosphate was adsorbed onto the three-layer modified membrane. PAH/PSS-modified CA/GO/SDS membrane is an innovative modification of the cellulose membrane for the phosphate-contaminated water system.

Researchers favour polymeric membranes for water treatment because of their excellent separation selectivity, high membrane performance, unique interconnected structure and inexpensive cost. Electrospinning, phase inversion, track-etching, slip casting, and film-stretching are some of the methods for fabricating polymeric membranes. Among them, electrospun nanofiber membranes (ENMs) are the most actively explored which address the fouling issues during wastewater treatment. It has a lot of advantages for wastewater treatment application. ENMs can be classified into inorganic and organic, and it is important to determine the type of membrane or polymer that is the most suitable for the application. The choice of membrane depends on many factors, including the composition of the operation parameters, application area and separation goals. Nevertheless, membrane fouling that results in poor rejection efficiency and membrane flux behaviour remain as challenges. Therefore, membrane surface modification has been widely embraced to improve the membrane process. Therefore, this review paper aimed to provide information on most common used inorganic and organic ENMs in wastewater treatment applications thus classifying the trends of ENMs applications on toxic heavy metal contaminants and hazardous chemical pollutants. It also provided insights into the future perspectives for ENMs in water treatment. We hope that his article can provide some guidance for a wide range of application in the membrane industry.