In this study, improvement of urea and creatinine permeability of polyethersulfone (PES) membrane by coating with synthesized tripolyphosphate-crosslinked chitosan (TPP-CS) has been conducted. Original and modified membranes, e.g. pristine PES, polyethersulfone-polyethylene glycol (PES-PEG) and PES-PEG/TPP-CS membranes were characterized using FTIR, DTG, SEM, AFM, water uptake, contact angles, porosity measurement, tensile strength test and permeation tests against urea and creatinine. The results show that the PES modification by TPP-CS coating has been successfully carried out. The water uptake ability, hydrophilicity and porosity of the modified membranes increase significantly to a greater degree. All modified membranes have good thermal stability and tensile strength and their permeation ability towards urea and creatinine increase with the increasing concentration of TPP-CS. PES membrane has urea clearance ability of 7.36 mg/dL and creatinine of 0.014 mg/dL; membrane PES-PEG shows urea clearance of 11.87 mg/dL and creatinine of 0.32 mg/dL; while PES-PEG/TPP-CS membrane gives urea clearance of 20.87–36.40 mg/dL and creatinine in the range of 0.52–0.78 mg/dL. These results suggest that the PES-PEG membrane coated with TPP-CS is superior and can be used as potential material for hemodialysis membrane.
Journal Article Effects of Methoprene on Lycoriella mali (Diptera: Sciaridae) Get access C. B. Keil, C. B. Keil Delaware Agricultural Experiment Station, Department of Entomology and Applied Ecology, College of Agricultural Sciences, University of Delaware, Newark, Delaware 19717 Search for other works by this author on: Oxford Academic PubMed Google Scholar M. H. Othman M. H. Othman Delaware Agricultural Experiment Station, Department of Entomology and Applied Ecology, College of Agricultural Sciences, University of Delaware, Newark, Delaware 19717 Search for other works by this author on: Oxford Academic PubMed Google Scholar Journal of Economic Entomology, Volume 81, Issue 6, 1 December 1988, Pages 1592–1597, https://doi.org/10.1093/jee/81.6.1592 Published: 01 December 1988 Article history Received: 26 October 1987 Accepted: 04 May 1988 Published: 01 December 1988
Polyvinylidene fluoride (PVDF) was chosen in this study as the main material in fabricating membrane due to its excellent chemical resistance and good thermal stability. Combination of triethyl phosphate (TEP) with DMAc produce better structure of membrane which safer and provide high mechanical strength for membrane. Surface modified PVDF hollow fibre membrane (HFM) was prepared using dry-wet spinning technique by varying air gap namely 10 cm, 20 cm and 30 cm. The morphology was evaluated using scanning electron microscopy (SEM), atomic force microscopy (AFM), mercury intrusion porosimetry (MIP), contact angle, tensile test and performing water flux testing. From the characterization data, PVDF HFM with 3 wt.% PEG 400, HFM 3-10 and HFM 3-20 referred as microfiltration membrane with pore size range 0.1-0.8 µm. While, HFM 3-30 act as ultrafiltration membrane with pore size ranging 0.01-0.1 µm. Experimental results revealed that by increasing the air gap from 10 cm to 30 cm, the porosity and finger-like length decreased due to the higher elongational stress that shift the pores from broad to narrow. Thus, PVDF HFM at 10 cm air gap, HFM 3-10 achieve the highest water flux due to the higher porosity, longer finger-like length and hydrophilicity achieved. The modified HFM at shorter air gap was found to be a promising membrane structure for excellence water performance and eco-friendly to environment.
Ceramic membranes, well-known for their high stability and resistance, are crucial in water filtration and treatment applications. However, they encounter challenges related to fabrication costs and operational lifespan. This review summarizes efforts to use low-cost ceramic materials, primarily those abundant in alumina (Al2O3) and silica (SiO2), as alternatives to overcome cost barriers. While these materials exhibit promising separation properties, their commercial viability is hindered by short lifespans and structural defects. Researchers have responded with multifaceted strategies to enhance the performance and durability of low-cost ceramic membranes. The article systematically delineates strategies to improve ceramic membranes, emphasizing increased ceramic content in low-cost materials. This approach enhances thermal and chemical stability, which is crucial for effective water treatment while boosting porosity, water flow, and filtration capacity. The review explores strategies to eliminate fouling and wetting resistance, including hierarchical structures, air pocket enhancement, and surface functionalization. Each technique presents distinct advantages and challenges, necessitating careful tailoring to specific application requirements. Durability is further addressed through two primary strategies, namely incorporating micro/nanomaterials and fabricating dual-layer ceramic membranes. While offering increased mechanical strength and separation performance, these methods pose challenges regarding material incorporation complexity and potential cost escalation. Achieving a balance between advantages and drawbacks is crucial for practical water filtration and treatment processes. In addition, the current study has explored the potential of strategies to enhance low-cost ceramic membranes, making them more competitive in water filtration and treatment processes.
The oxidation kinetics and microstructure characteristics of oxide scales thermally grown on the surface of developed FeCr alloy were investigated at 900 °C. The influence of difference sintering technique, i.e. spark plasma sintering and hot pressing, to improve nanostructured alloy performance was studied. The La-implantation was also considered in this study. It was found that the SPS sintered sample showed better performance than the HP sintered sample. Moreover, it also found that a combining of La-implantation and nanostructured alloy was most beneficial. While nanostructured alloy reduced the oxidation rate, the La-implantation increased the Cr 2 O 3 scale conductivity.
Pretreatment of produced water using ceramic membrane is considered promising due to its excellent separation performance and thermal and mechanical stabilities, however, the high cost of ceramic membranes discourages industries for large scale applications. The purpose of this work is to fabricate ceramic hollow fibre membranes from alumina-spinel composite powder synthesized from low-cost aluminium dross waste for the pretreatment of oily saline produced water. The hollow fibre membranes were prepared via phase inversion-based extrusion and sintering technique. Aluminium dross (less than 50 µm) was subjected to pre-treatment via water leaching and calcination, resulting in alumina (Al2O3) and spinel (MgAl2O4) as major constituents. Subsequently, the as-prepared alumina-spinel composite powder was used as a ceramic material in fabricating the hollow fibres. The effect of sintering temperatures on the morphology, crystalline phase, pore size and porosity, mechanical properties, and removal efficiencies of the alumina-spinel composite hollow fibre membranes were investigated. The microfiltration test of the hollow fibres was assessed using produced-water feed of 200 mg L−1 at 1 bar. The hollow fibre sintered at 1275 °C offers 92.41% rejection percentage of oil, the highest after 50 min of stable flux. Furthermore, turbidity was found to decrease from 378 NTU to 28.5 and 22.5 NTU for hollow fibres sintered at 1250 and 1275 °C after 2 h of filtration. In this work, the alumina-spinel composite hollow fibre membranes are found to be an effective tool as an alternative for the pretreatment of oily saline produced water.
An efficient and facile production of highly favorable graphene oxide (GO) via modified Hummers’ method at different oxidation degrees was successfully demonstrated. The formation of oxygen containing functional groups and their effects on GO structural properties were analyzed by UV–visible spectrophotometry (UV–vis), Fourier transform infrared spectroscopy (FTIR), x-ray diffraction (XRD) and Raman spectrophotometer. The presence of hydroxyl (-OH), carboxyl (-COOH), epoxy (COC) and carbonyl (CO) groups in GO and their intermolecular interaction were analyzed by FTIR. XRD pattern of GO showed the dominant peak at 10.8° with interlayer spacing (0.82 nm) larger than pristine graphite (0.34 nm) owing to the addition of oxygen with functional groups. High-resolution transmission electron microscopy (HRTEM) analysis showed highly transparent layers of GO-9 with distinct flake like shape. The electrochemical property of GO was observed to increase with lower amount of oxygen containing functional groups. These synthesized GO with valuable properties have high potential to serve as a precursor for the production of various graphene-based materials application.
Half-metallic nanocrystalline magnetite (Fe3O4) thin films, with different thicknesses were developed on polyethylene-terephthalate (PET) substrates, by reactive sputtering at room temperature. Fe3O4 film (200-nm thick)/PET heterostructures possess superior electrical and magnetic characteristics, with a Verwey transition temperature (Tv ) of ~122 K and a saturation magnetization (Ms) ~ 361 emu/cm3. Furthermore, the antiferromagnetic (AFM)-coupled antiphase boundaries (APBs) controlled the transport properties of the Fe3O4 thin films, due to the tunneling of spin-polarized electrons through the films. Very-high magnetoresistance (MR) value (−8.9%) were observed for H ‖ Film plane, constructed from Fe3O4 (200-nm thick)/PET when H values were below 60 kOe at 300 K. In addition, flexibility tests, to examine resistivity, M-H and MR, were performed using with 90° and 45° bent angles and cyclability experiments were implemented to validate the reproducibility of these characteristics. These outcomes demonstrated that Fe3O4/PET heterostructures may represent a promising candidate for flexible/wearable spintronics.
Adsorption is one of the most efficient ways to remove heavy metal from wastewater. In this study, the adsorptive removal of hexavalent chromium, Cr (VI) from aqueous solution was investigated using natural zeolite, clinoptilolite, in the form of hollow fibre ceramic membrane (HFCM). The HFCM sample was prepared using phase inversion-based extrusion technique and followed by sintering process at different sintering temperatures in the range of 900–1050 °C. The fabricated HFCM was characterised using scanning electron microscopy (SEM), contact angle, water permeability, and mechanical strength for all HFCMs sintered at different temperatures. The adsorption and filtration test of Cr (VI) were performed using an in-house water permeation set up with a dead-end cross-flow permeation test. An asymmetric structure with sponge- and finger-like structures across the cross-section of HFCM was observed using SEM. Based on the characterisation data, 1050 °C was chosen to be the best sintering temperature as the water permeability and mechanical strength of this HFCM were 29.14 L/m2∙h and 50.92 MPa, respectively. The performance of the HFCM in adsorption/filtration was 44% of Cr (VI) removal at the Cr (VI) concentration of 40 mg/L and pH 4. In addition, the mathematical model was also performed in simulating the experimental data obtained from this study. All in all, the natural zeolite-based HFCM has a potential as a single-step Cr (VI) removal by membrane adsorption for the wastewater treatment.
The objective of this study was to evaluate the capability of Polyamide (PA) thin film composite (TFC) membrane immobilized with Titanium Dioxide (TiO 2 ) particles on the removal of Endocrine Disruptive Compounds (EDC). Since 1990`s, an increasing environmental pollution by EDC had been noticed, for instance in surface waters, agricultural areas, and atmosphere, especially since the analytical methods for EDC detection have been continuously improved. The estrogenic properties of bisphenol A (BPA), a ubiquitous synthetic monomer which categorized as an EDC that can leach into the food and water supply, have prompted considerable research into exposure-associated health risks in humans. In this study, PA/TiO 2 TFC membrane was fabricated via interfacial polymerization (IP), using Polysulfone (PSf) flat sheet as substrate membrane. Trimesoyl chloride (TMC) and m-phenylenediamine (MPD) have been used as monomer and aqueous solution, respectively. The performance of PA/TiO 2 TFC membrane and PSf substrate membrane on the removal of BPA has been compared and analysed. The membrane was analyzed for several characterizations using Field Emission Scanning Electron Microscopy (FESEM) and water contact angle analysis. Synthetic wastewater using 100ppm of BPA solution has been prepared for membranes performance. The existence of PA/TiO 2 TFC on top of PSf membrane has been confirmed by FESEM and EDX image. Meanwhile, the hydrophilicity of PSF membranes has been improved with the existence of TFC which is good for water treatment system since it improves membrane’s pure water flux. The rejection of BPA has been done using ultrafiltration system and it was found that PA/TiO 2 TFC membrane could reject almost 99% of BPA from feed solution. From the data obtained in this study, the TFC membrane is found to be convincing for wastewater treatment that contains EDC.
This study presents a facile approach to produce hydrophobic ceramic hollow fiber membranes (CHFMs) for membrane distillation (MD) desalination using the polymethylhydrosiloxane/tetraethylorthosilicate (PMHS/TEOS) hybrid material. The CHFM was modified via dip-coating with PMHS/TEOS hybrid solution followed by post-coating spinning to facilitate the formation of pores on the coating layer. The effects of ethanol and PMHS concentrations on the coating layer structure and hydrophobicity of the membranes were studied. CHFMs acquired hydrophobic properties after surface modification with the water contact angle values in the range of 108.2° to 124.1°. These membranes showed outstanding direct contact MD (DCMD) desalination performance with salt rejections of >99.98%. A flux of 6.7 L/m2h was achieved by the surface-modified CHFM when treating feed solution with a salinity of 35,000 ppm.
