Catalytic Hollow Fibre Membrane Micro-reactors for Energy Applications

An asymmetric ceramic hollow fibre is proposed as a substrate for the development of a catalytic hollow fibre microreactor (CHFMR) and a catalytic hollow fibre membrane microreactor (CHFMMR). The ceramic substrate that is prepared using the phase inversion and sintering technique has a finger-like structure and a sponge-like region in the inner region and the outer surface respectively. The finger-like structure consists of thousands of conical microchannels distributed perpendicularly to the lumen of ceramic hollow fibres onto which a catalyst is impregnated using the sol-gel Pechini method to improve a catalytic reaction. To further enhance the catalytic reaction, a membrane has been incorporated on the outer layer of ceramic hollow fibre. This study focuses on the use of palladium (Pd) and palladium/silver (Pd/Ag) membranes to separate hydrogen from reaction zones in the water-gas shift (WGS) reactions and the ethanol steam reforming (ESR) respectively. In the development of CHFMMR, the fabrication of Pd and Pd/Ag membranes is carried out prior to the catalyst impregnation process to avoid the dissolution of catalyst into the plating solution due to the presence of ammonia and ethylenediaminetetraacetic acid (EDTA). The catalytic activity tests show that the CHFMR, that does not have the Pd membrane on its outer surface, improves the carbon monoxide (CO) conversion compared with its fixed-bed counterpart. The presence of conical microchannels is expected to enhance the activities of the catalyst in the substrate. The incorporations of Pd and Pd/Ag membranes on the outer layer of ceramic hollow fibres enable pure hydrogen to be produced in the shell-side for both the WGS reaction and the ESR. The CHFMMR is used to remove one of the products enabling the WGS reaction to favour the formation of product. It also facilitates the small amount of catalyst to be used to produce significant amount of hydrogen in the ESR

Preparation and characterisation of inexpensive porous kaolin hollow fibre as ceramic membrane supports for gas separation application

Low-cost, porous ceramic kaolin-based hollow fibre membrane support (HFMS) for gas separation application was developed via phase inversion technique. The ceramic suspensions with various ratios of kaolin to polyethersulfone (PESf) binder (5:1 to 9:1) were extruded and then sintered at 1200 to 1500 °C. The HFMSs were characterised by several analyses to investigate the effects of kaolin/PESf ratio and sintering temperature on the sample properties. The results showed that the kaolin/PES ratio and sintering temperature affected the considerable structure and physical properties of the kaolin membrane. It is observed that with increasing sintering temperature, the porosity and gas permeation of the HFMS decreased, while the bending strength and density of the HFMS increased. As a result, a porous HFMS with sufficient mechanical strength and high gas permeation characteristics is achievable if the appropriate kaolin/PESf ratio and sintering temperature are chosen

Hydrophobic ceramic membrane for membrane distillation: A mini review on preparation, characterization, and applications

Membrane distillation (MD) is one of the emerging separation technologies with extremely high separation factor, especially in desalination application. MD utilizes the hydrophobic membrane which only allows the passage of vapor through the membrane pores. Recent years have witnessed great progress in the development of hydrophobic ceramic membranes for MD applications due to their superior properties over the polymeric counterparts. However, ceramic membranes are hydrophilic in nature; hence, membrane surface modification process is required to acquire hydrophobic properties for MD applications. Direct grafting using silane agents is the most widely used ceramic membrane hydrophobization method. Hence, this mini review provides a complete summary of the research progress on the preparation and characterization of the hydrophobic ceramic membranes through silane agent grafting, as well as their applications in MD. Finally, future research directions have also been addressed

Comparative study of Malaysian and Nigerian kaolin-based ceramic hollow fiber membranes for filtration application

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

Preparation and characterization of superparamagnetic magnetite (Fe3O4) nanoparticles: a short review

Magnetic magnetite (Fe3O4) nanoparticles have attracted a great deal of attention in both fundamental research and practical applications over the past decades. Down to the nanoscale, superparamagnetic Fe3O4 nanoparticles with only a single magnetic domain exhibit high magnetic susceptibility, which provides a stronger and faster magnetic response. Their superparamagnetic properties together with other intrinsic properties such as low toxicity, high surface area-to-volume ratio and simple separation methodology, making them ideal for environmental remediation, biomedical, and agricultural applications. This review discusses three conventional wet chemical methods, including chemical co-precipitation, sol-gel synthesis and thermal decomposition for the preparation of superparamagnetic Fe3O4 nanoparticles with controlled size and magnetic properties. Nowadays, with the growing research interest in Fe3O4 nanoparticles, there is a great amount of researches reported on efficient routes to prepare size-controlled magnetic nanoparticles. Thus, this review is designed to report the recent information from synthesis to the characterization of Fe3O4 nanoparticles as well as the discussion of future perspective in this research area

Feasibility study of small core diameter polymeric optical fibers (POF) from poly(methyl methacrylate)

This work describes the fabrication and evaluation of small core diameter Polymeric Optical fibres (POF) prepared from Poly(Methyl Methacrylate) (PMMA). Based on prior study, POF has a very interesting property in terms of short-reach local area networks due to the simpler manufacturing process and inherent immunity to electromagnetic interference and radiation. It can overcome the limiting factors of conventional glass-based optical fibre in terms of cost-effective, flexibility and easy installation. This study focused on introducing effective fabrication method to produce small diameter PMMA POF core using extrusion process. Prior to extrusion, we managed to produce PMMA cores with diameters of 650 μm, 750 μm and 850 μm. Based on the outcome of this study, the drawing tension and extrusion temperature have been identified as major influences on core diameter. The SEM images indicated that dense structure and clean surface whereas DSC and TGA analyses revealed that almost similar glass transition temperature and degradation weight loss in between fabricated PMMA core and industrial polymer optical fibre

Development of hydrophobic metakaolin hollow fibre membrane for membrane distillation application

Metakaolin hollow fibre membranes (MHFM) was prepared by a combined phase inversion and sintering method for direct contact membrane distillation (DCMD) application. Four hydrophobic metakaolin hollow fibre membranes (h-MHFM) sintered at different temperatures (1200ºC to 1500ºC) were successfully prepared by grafting 1H,1H,2H,2H-perfluorodecyltriethoxysilane on the MHFM. Prior to the grafting process, the MHFM was hydrolysed with a mixture of ethanol and water with the ratio of 1:2 for 24 hours. The effectiveness of the hydrophobization on each MHFM was assessed using contact angle measurement, scanning electron microscopy (SEM) and three-point bending test. It was found that the increasing sintering temperature improved the mechanical strength from 117.6 MPa to 182.3 MPa. Further increment in mechanical strength was also observed after the modification with fluoroalkylsilane (FAS). The contact angle of the membrane was enhanced up to 120˚ after modification. In general, the membrane prepared at low sintering temperature of 1200°C exhibited the highest DCMD performance with the water vapor flux of 17.5 kg/m2h due to the sufficient pore size for the vapor to pass through the membrane structure

Preparation of high performance SPEEK/Cloisite 15A nanocomposite membrane via advanced membrane formulation method

Sulfonated poly (ether ether ketone) (SPEEK)/Cloisite 15A® nanocomposite membranes were prepared via solution intercalation method. For better dispersion of nanoclay in the polymer matrix, the solution intercalation method was modified and a compatibilizer was introduced. The state of nanoclay dispersion was determined by FESEM. The effect of the solution formulation preparation method and compatibilizer on the performance properties such as proton conductivity and methanol permeability of all membranes was studied. FESEM analysis confirmed that SPEEK/Cloisite 15A® nanocomposite membrane prepared via modified solution intercalation method and in the presence of compatibilizer was the best membrane in terms of its morphological structure. Due to its well nanoclay distribution in polymer matrix, this kind of membrane exhibited the highest selectivity owing to its high proton conductivity and low methanol permeability. SPEEK/Cloisite 15A® with compatibilizer prepared via modified solution intercalation method was found to be the best membrane

Titanium dioxide incorporated thin film composite membrane for bisphenol A removal

The objective of this study was to evaluate the capability of Polyamide (PA) thin film composite (TFC) membrane immobilized with Titanium Dioxide (TiO2) 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/TiO2 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/TiO2 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/TiO2 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/TiO2 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

Fabrication of polycarbonate-based polymer optical fiber cladding: effect of different solvents

Normally, the cladding layer is fabricated by using heat through continuous extrusion, melt spinning, batch extrusion, and heat drawing technique. These techniques require high temperature precision in order to obtain the desired morphology of the cladding without compromising the quality of the polymer. Hence, in this study dip-coating method was utilized to coat the polycarbonate (PC) core with poly (methyl methacrylate) (PMMA) as a cladding part. The PC core was dipped into different cladding solutions using three types of organic solvent (i.e. Tetrahydrofuran (THF), N-Methyl-2-pyrrolidone (NMP), and Dimethylacetamide (DMAc) and subjected to post-treatment process. The thickness of fabricated cladding layer was ~10–15 μm for all coating solutions. The cladding prepared by THF exhibits transparent layer wrapping the core. However, the cladding layers for PMMA dissolved in NMP and DMAc showed translucent appearance. The THF/PMMA solvent displayed ~98 % transmittance at visible region which was higher than NMP/PMMA and DMAc/PMMA. The failure strain (3.6 %) and tensile strain (88.98 MPa) of THF/PMMA sample were higher compared to other solutions. Young’s modulus which measures the stiffness and represents the breakability of a solid material was lower for THF/PMMA. Therefore, the THF is the most appropriate solution for fabrication of PC-based POF cladding layer