Various Endocrine Disrupting Compounds (EDCs) either natural or synthetics have been identified including bisphenol A (BPA), dioxin, polychlorinated biphenyls, and dichlorodiphenyltrichloroethane (DDT). These compounds which present widely in the product of solvent industry, agricultural, pharmaceuticals and household convenience may directly or indirectly interrupt the normal function of endocrine system. Recently, the EDCs threats to human health have led to the increasing demand of clean water sources which excites a challenge for the contaminants removal processes. Conventional treatment methods may not completely remove the contaminants, meanwhile advanced oxidation process (AOPs) especially photocatalysis have been proven efficient in removing the contaminants. Even though photocatalysis is efficient in suspension of either nano-or microscale, the immobilizing TiO2 in the membrane matrix for catalyst separation purposes have decreased the adsorption of organic substances on the TiO2 surface with potential loss of TiO2 during long-time usage. This lead to the emerging in the exploration and fabrication of dual layer hollow fiber (DLHF) membrane for better performance of immobilized TiO2. Therefore, we exploit this fact to investigate the incorporation of photocatalysis into dual-layer hollow fiber membrane which are believed may improve the photocatalytic degradation and separation efficiency. The FESEM results showed that both layers are compatible with each other and there are no delamination found between layers. The presence of outer layer does not influence the surface roughness; however improve the hydrophilicity and membrane strength. Altogether, photocatalytic dual layer hollow fiber (DLHF) membrane was successfully fabricated using co-extrusion technique.
As nutrients shortage that will occur by the next decade could limit global fertilizer production, there are growing needs to recover macro-nutrients such as P and N from landfill leachate, which its generation and treatment have become global environmental issues. This work critically reviews the applicability and the performance of physico-chemical treatments for nutrient recovery from landfill leachate. This article also identifies recent progress and bottlenecks of nutrient recovery from landfill leachate, while providing an overview of how to apply a circular economy paradigm in the nexus of water–food–energy. Due to their ability to recover P and N from landfill leachate, specific attention is given to struvite precipitation, adsorption, and ammonium stripping. Their technological strengths and bottlenecks of each technique are evaluated based on a literature survey of 145 papers (1981–2022). By integrating anaerobic digestion and other nutrient recovery technologies, it is possible for water utilities to provide both renewable energy and nutrients, while contributing to a circular economy, global food security, and carbon neutrality. To attain a sustainable landfill management, the selection of appropriate technology for nutrient recovery from the liquid waste needs to consider the properties of waste stream, recovery performance, discharge standard, impacts, and cost-effectiveness. Overall, this work has consolidated new knowledge between technological development and demand-driven valorization.
High wetting resistance and high permeate flux are crucial for membrane distillation (MD) to achieve a high performance. To achieve both of these qualities, this work focused on the fabrication of co-extruded dual-layer hollow fibre polyvinylidene fluoride nanocomposite membranes with hydrophobicity gradients. The nanocomposite membranes were incorporated with hydrophobised carbon-based nanoparticles, i.e. multi-walled carbon nanotube (MWCNT) and graphene nanoplatelet (GNP). The effect of different concentrations of nanoparticles (0, 1 and 2 wt%) on the properties and MD performance of the membranes were investigated. The outer layers of the nanocomposites membranes were more hydrophobic than the neat membrane, and the membrane containing 2 wt% of hydrophobised GNP exhibited the highest contact angle of 111.1°. All the inner layers of the membranes were found to be hydrophilic with contact angle of about 60°, thus proving that hydrophobicity gradients were achieved in the membranes. All the membranes had pore sizes and porosities around 0.1 μm and 21.8–42.9% respectively, which are suitable to be used in MD. The surface roughness and wetting resistance of all the nanocomposite membranes, especially the ones with GNP, were higher than the neat membrane and the values increased with increasing concentration of nanoparticles. These membrane characteristics had effects on the direct contact MD (DCMD) performance where all the nanocomposite membranes showed better flux than the neat membrane. The membrane incorporated with 2 wt% of hydrophobised GNP achieved the highest flux of 8.27 kg/(m2h). All the membranes achieved salt rejections of more than 99.9%.
The membrane contactor system is one of the most important technologies to trap CO 2 from natural gas. To apply this technology, hollow fibre membranes with a superhydrophobic surface must be used. Three types of fluoroalkyl silane (FAS) molecules [C6, C8, C10] at different immersion times (6, 24, 48,72 h) were used to modify kaolin hollow fiber membrane into the superhydrophobic property to capture CO 2 from natural gas via contacting gas-liquid system. The kaolin was chosen due to its abundantly available at an affordable price as well as a high amount of groups hydroxyl (OH) in the surface which easily reacts with (FAS) during the grafting process. Superhydrophobicity was distinguished by Fourier transforms infrared (FTIR), scanning electron microscope (SEM), liquid entry pressure of water (LEPw) measurement, and contact angle (CA). The chosen superhydrophobic kaolin membrane was tested for carbon dioxide (CO 2 ) capture via the membrane contactor system. With increasing time of immersion, the hydrophobicity phenomena raised gradually until superhydrophobicity property was obtained. It was proved that the 48 hours was sufficient time to obtain the desired superhydrophobicity property to avoid wetting pores of the membranes. Besides, the perfect type of FAS for separation CO 2 was C8 based on sufficient LEPw and contact angle. The reduction of pH was observed after testing the performance of using membrane contactor to separate CO 2 by water as absorbent where pH value was reduced from 6.6 to 4.3 within one hour, which concludes that the success of the gas-liquid system to remove CO 2 from natural gas.
Membrane technology has attracted much attention due to its extensive separation and purification applications in the industries. Apart of efficient separation performance, some membranes have been reported to possess adsorption properties, which further improve the purification process at the final stage. This review will focus on discussing the development of adsorptive membrane started from material selection, membrane preparation, and characterization and performance evaluation. This study will emphasize the innovation of membranes in treating common waste, such as dye pollutant, using inorganic material such as ceramic. Future research directions will be discussed in the context of new research direction, especially those related to the application of hollow fiber membrane and those related to dye waste treatment.
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Sulfonated poly(ether ether ketone) (SPEEK) membranes have been prepared as a potential polymer electrolyte membrane (PEM) for direct methanol fuel cell (DMFC) application. The SPEEK polymer was dissolved into N, N-dimethylacetamide (DMAc) in a subsequent step after sulfonating the raw polymer with concentrated sulfuric acid. The polymer solutions were then cast by pneumatic casting machine. The influence of sulfonation reaction temperature on ion exchange capacity (IEC) and degree of sulfonation (DS) havebeen investigated. The results showed that the IEC and DS are increased with the temperature. The resulting membranes were then characterized by evaluating their physicochemicalproperties such as methanol permeability and proton conductivity as a function of DS. The overall results showed that sulfonation process successfully enhanced the protonconductivity of the membrane and the values were comparable with commercial membrane, Nafion® 117, at room temperature. Although the methanol permeability of membrane alsoincreased after sulfonation process and proportional with DS, the value was still lower than Nafion® 117.
