Low-cost mullite-kaolinite material has recently received more attention as an alternative to conventional ceramic materials such as alumina and silica to prepare ceramic hollow fibre membranes (CHFMs) due to its high alumina contents and silica and thermal/chemical stability. However, weak bending strength is still one of the key bottlenecks that delay their commercial applications. In this work, we successfully fabricate a novel mullite-SS HFM with enhanced bending strength using mullite-kaolinite power with different stainless steel alloy (SS) 316 L contents of 0.0, 2.5, 5.0, 7.5, 10 and 12 % (w/w) as a reinforcement material by phase inversion/sintering techniques. The SS alloy was a potential material to enhance the mechanical strength of mullite HFMs due to its excellent mechanical properties. The effects of the major fabrication parameters of SS contents, mullite contents, and fabrication parameters such as air gap distance and bore fluid flow rates were well studied and evaluated through the fabrication process. Fabricated mullite-SS HFMs were characterized by morphology, porosity, pore size/pore size distribution, and bending strength. Afterwards, they were evaluated in an oil/water separation system regarding water flux and oil rejection rate. Based on the findings, there was a gradual increase in the bending strength from 32.1 to 79.8 MPa with increased SS contents from 0 to 12 % (w/w). At 10 % (w/w) SS, the satisfactory morphology with the balance between the bending strength of 66.7 MPa and porosity of 29 % was obtained. This bending strength was significantly higher than reported for mullite-kaolinite HFMs in previous works. Moreover, At 10 % (w/w) SS, the oil–water rejection performance of 96.9% and the water permeation of 290 L/m2. h was satisfactory at the sintering temperature of 1300 °C. These findings suggest the advantage of this membrane for various water treatment applications, such as oil/water separation, due to its outstanding physical properties.
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This chapter discusses the fabrication of dual-layer hollow fiber membranes with different TiO2 loadings in the outer layer by a single step co-extrusion technique. It analyzes the catalytic efficiency of the immobilized TiO2 with a different ratio of TiO2/polyvinylidene fluoride in the outer layer of the dual-layer hollow fiber membranes using a hybrid photocatalytic membrane reactor system. In the photocatalytic degradation of employing dual-layer hollow fiber membranes, only the outer layer is responsible for the reaction to take place due to the presence of TiO2 nanoparticles as a photocatalyst. The co-extrusion approach can be employed to produce multi layer-sheets, wire coating and other products. The incorporation of inorganic additives into polymeric membranes has been widely investigated for microfiltration, ultrafiltration, nanofiltration and membrane distillation. The increasing number of TiO2 particles on the membrane surfaces would provide additional hydrophilicity strength to the membranes, possibly increasing the permeate water flux and its antifouling properties.
No abstract is provided for this article.
No abstract is provided for this article.
Ceramic membrane has gained increasing interest in water filtration application due to its inherent characteristics. Low-cost clay materials are preferred to fabricate an efficient and cost-effective ceramic membrane. Among the ceramics, kaolin displays better mechanical, thermal, and chemical properties. However, natural properties of kaolin vary from different studies. Hence, cost-effective Nigeria (NK) and Malaysia (MK) kaolins were compared to study the fabrication of kaolin hollow fiber ceramic membrane for filtration application. The effects of kaolin loading concentration (34 and 37 wt. %) and sintering temperature (1200, 1350, 1400, and 1500 °C) on kaolin membrane fabrication were also studied. XRF studies indicated that the hydroxyl silica and alumina compositions were 56.76wt.% and 41.97wt% for NK and 55.21wt.% and 40.33wt% for MK. MK exhibited intense kaolinite peak with a broad range of particle size distribution. The mechanical stability of kaolin ceramic membrane increased with the increase of sintering temperature and kaolin loading concentration. Membrane morphology also varied with MK and NK. Interestingly, 34wt% kaolin at a sintered temperature of 1350 °C produced ceramic membrane with a high water flux. A similar trend was observed in both MK and NK, where the flux of 34wt% MK and NK are 565 and 460 L/m2h, respectively.
This chapter provides a comprehensive overview of blending techniques for photocatalytic membrane fabrication involves the strategic incorporation of photocatalytic materials into the membrane matrix, enhancing the membrane’s functional capabilities by combining separation or filtration processes with the ability to catalyze chemical reactions under light exposure. Various blending methods including phase inversion method, in-polymerization and electrospinning, are explored, each with its unique mechanisms. The chapter discusses the selection of photocatalytic and membrane materials, emphasizing their compatibility and synergistic effects. The chapter also highlights the controlled customization of composite membranes, enabling tailored properties for specific applications. The advantages and limitations of the blending method are also addressed to maximize the effectiveness of the photocatalyst inside the membrane and ensure consistent performance across the entire membrane surface. This chapter serves as a valuable resource for researchers, engineers, and professionals seeking insights into the design, fabrication, and applications of photocatalytic membranes through blending methodologies.
A facile, rapid, green, and novel clean synthesis of advanced RGO/bimetallic Pt-Pd alloy/CeO2 nanocomposite electrocatalyst with the enhanced electrocatalytic performance of methanol oxidation reaction (MOR) has been successfully carried out through a one-step hydrothermal-assisted formic acid reduction reaction without applying any template or surfactant. The as-prepared electrocatalysts were extensively characterized by X-ray Powder Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Energy Dispersive X-ray Spectroscopy (EDX), High-Resolution Transmission Electron Microscopy (HRTEM), and Field-Emission Scanning Electron Microscopy (FESEM) to confirm the formation, deposition and homogenous distribution of Pt-Pd alloy and CeO2 nanoparticles (NPs) on the surface of RGO. Meanwhile, the electrocatalytic activity and the long-term stability performance of the as-prepared electrocatalysts towards MOR were employed by cyclic voltammogram and chronoamperometry, respectively. Noticeably, the as-prepared RGO/bimetallic Pt-Pd alloy/CeO2 nanocomposite electrocatalyst presented very outstanding electrocatalytic performance with higher maximum forward peak current density (69.82 mA cm−2) than those of RGO/monometallic Pt/CeO2 (23.81 mA cm−2) and RGO/monometallic Pd/CeO2 (1.39 mA cm−2) toward MOR in acidic medium denoting to the large surface area and excellent conductivity of RGO, homogenous distribution of Pt-Pd alloy electrocatalyst as well as a synergistic effect between Pt-Pd alloy NPs, RGO, and CeO2 NPs. Moreover, the RGO/bimetallic Pt-Pd alloy/CeO2 electrocatalyst also possesses excellent stability and exceptional poisoning tolerance through the advantages of utilizing Pt-Pd alloy NPs and the synergistic effect of CeO2 NPs. Therefore, this study may open a new facile route with the convenient experimental procedure, clean, reasonable cost, easy to handle, no time consuming, and easy to scale-up for the large quantity production of an advanced anode electrocatalyst for direct methanol fuel cell application.
This study investigated physico-chemical interactions among Cu(II), biogenic materials, and Fe2O3 in a continuous-flow biofilm reactor system under a well-controlled environment. The effects of Fe2O3 and bacterial biofilms on the distribution of Cu(II) in a simulated aquatic environment were studied. To control biological and abiotic elements in the marine environment, a biofilm reactor was designed to understand the metal speciation of Cu(II) and its distribution. The reactor consisted of a biofilm chamber equipped with glass slides for biofilms attachment. Due to its ability to grow as biofilm in the medium, Pseudomonas atlantica was cultivated to adsorb trace Cu(II) to attached and suspended cells. It was found that biofilms with 170–285 mequiv chemical oxygen demand (COD) concentration/m2 of total oxidizable materials accelerated the Cu(II) adsorption to the surface of the reactor significantly by a factor of five. A significant inhibition to the bacterial growth took place (p ≤ 0.05; t-test) when Cu(II) concentration was higher than 0.5 mg/L. In the absence of Cu(II), bacterial cells grew normally to 0.075 of optical density (OD). However, at the Cu(II) concentration of 0.2 mg/L, the cells grew to a lower OD of 0.58. The presence of glycine and EDTA substantially reduced the toxicity of Cu(II) on bacterial growth (p ≤ 0.05; paired t-test). Their complexation with Cu(II) rendered the metal ions less available to bacterial cells. This implies that the Fe2O3 and bacterial biofilm affected Cu(II) distribution and speciation in the aquatic environment.
No abstract is provided for this article.
Membrane wetting is one of the main obstacles that inhibits a membranes’ performance for membrane distillation. The aim of this research is to examine the effect of ZnO Nps re-entrant structure loading on polyvinylidene fluoride (PVDF) membrane surface for seawater desalination via direct contact membrane distillation. The deposition of ZnO Nps onto the PVDF hollow fiber membrane surface via dip-coating and followed by membrane fluorination using fluoroalkylsilane. During the dip-coating process, ZnO Nps were varied at different concentrations, ranging from 1, 2, and 3 wt%. The results showed that the surface morphology of the omniphobic membrane which exhibited a higher concentration of ZnO Nps led to an improvement in the contact angle values for all tested liquids. Furthermore, it also led to the improvement of the membrane surface roughness and liquid entry pressure (LEP) of the omniphobic membrane. The desalination performance of the FAS-P-3WT%-T membrane in the presence of humic acid as a foulant exhibited an excellent water flux value of around ∼6 L/m2h coupled with an outstanding salt rejection performance close to 100 %. The higher loading of ZnO Nps as a re-entrant structure can significantly improve the anti-wetting properties as well as performance of PVDF-based membrane.
The present research investigated the utilizing of single and dual-layer flat sheet mixed-matrix membranes (MMMs) for carbon dioxide (CO2) separation. In this research, zeolite 4A is incorporated into a processable polymeric material, polyethersulfone (PES) of MMMs to get the high selectivity and permeability of membrane. Single-layer flat sheet MMMs have been successfully fabricated by adjusting the weight percent of zeolite loading in total solid as the effect of zeolite loading on the performance of MMMs were investigated. It shows that the higher the zeolite loadings, the higher the CO2/CH4 selectivity which is from 1.54 at 0wt % zeolite loading to 3.20 at 20wt % zeolite loading. Besides that, dual-layer flat sheet MMMs was also successfully fabricated with blending of PES and zeolite as selective top-layer and neat PES as sub-layer. Comparison of the results of permeability and selectivity between single and dual layer MMMs with same zeolite loading were studied. The performance of these newly developed dual-layer flat sheet of MMMs gives the best result with CO2/CH4 selectivity for dual layer MMMs is 9.63, tripled of the selectivity of single layer MMMs, 3.20.
A new Silicanizing process on formation of coating on mild steel using Tronoh Silica Sand (TSS) is presented. The process was performed in the temperature range 1000- 1100°C and with varying deposition time of 1-4 hours. Influence of the layer and the substrate constituents on the coating compatibility of the whole silicanized layer is described in detail. Morphology and structure of the silicanized layer were investigated by XRF, XRD and SEM. It is observed that diffusion coatings containing high concentrations of silica which profile distribution of SiO2 in the silicanized layer was encountered and the depth from the surface to the substrate was taken as the layer thickness. The results also depicted that a longer deposition time have tendency to produce a looser and larger grain a hence rougher layer. The silicanized layer composed of FeSi and Fe2SiO4 phases with preferred orientation within the experimental range. It is also found that longer deposition time and higher temperature resulted in an increase in SiO2 concentration on the substrate (mild steel).
