Novel CGO/NiO–CGO dual-layer hollow fibres (HFs) have been fabricated in a single-step co-extrusion and co-sintering process. LSCF–CGO cathodes layers were then deposited onto the dual-layer HFs to construct micro-tubular SOFCs. The NiO in the micro-tubular HF–SOFCs was reduced at 550°C using hydrogen gas to form Ni anodes. Scanning electron microscope images showed that the dual-layer HFs have porous anodes and dense electrolyte layers. Preliminary measurements with a HF–SOFC fed with H2 and atmospheric oxygen, produced maximum power densities of 420Wm−2 and 800Wm−2 at 450°C and 550°C, respectively.
A sufficient volume fraction for pore development is provided by an appropriate cathode thickness, while its solid volume fraction for cathode reaction sites is preserved. As this study involves a simplified fabrication technique, adjusting the cathode extrusion rate could influence the anode and electrolyte layers since they are co-extruded and co-sintered. Thus, the effect of cathode extrusion rates (between 3 ml min-1 to 6 ml min-1) on the triple layer anode/electrolyte/cathode MT-SOFC developed via phase inversion-based co-extrusion/co-sintering is examined in this study. The cathode suspension is subjected to large forces to be extruded using a high cathode extrusion rate of 6 ml min-1, which indirectly pushes the electrolyte layer to a thinner state, promoting better ions' hopping efficiency by reducing the pathway between the cathode and anode. Additionally, the anode thickness increased with increasing cathode extrusion rate, providing ample electrode reaction sites and thereby enhancing the gas diffusion process. Accordingly, the C6 sample achieves a maximum power density of 1.46 W cm-2 with 1.08 V OCV at an optimum operating temperature of 800 °C, which is high for MT-SOFCs in high-temperature applications. Hence, the optimal cathode extrusion rate for the MT-SOFC fabricated using this simplified method was 6 ml min-1.
Water scarcity at global level has called for attentions to establish new and innovative technologies that can be tapped to provide sustainable solutions to water crisis. Membrane-based desalination has been acknowledged as one of the promising approaches to resolve the global challenges. Currently, different membrane-based technologies have been deployed worldwide for clean water production. However, despite the great advances made in terms of the permeate flux and rejection, the practical application of membrane for desalination is still limited by the inevitable membrane fouling issue. Membrane fouling is known to be the major culprit to the elevated operating costs due to the deterioration of permeate flux, increasing transmembrane pressure, and frequent chemical cleaning which shorten the membrane's lifespan. This review provides insights into the recent advancement in mitigating membrane desalination fouling. The fouling control strategies which encompass the efforts made in the novel membrane development, feed water pretreatment, and membrane cleaning are highlighted. The advantages and limitations of these techniques are discussed and reviewed based on a substantial number of up-to-date literatures.
No abstract is provided for this article.
One-dimensional photocatalysts with enhanced properties are desirable for photocatalytic degradation of organic pollutants. In this work, hollow titanium dioxide nanofibers (HTNF) were successfully prepared via template synthesis technique. Firstly, polyacrylonitrile (PAN) nanofibers were synthesized by electrospinning and oxidized for further use. By dip-coating the electrospun nanofibers in TiO2 sol–gel, TiO2/PAN nanofibers composite was obtained. Subsequently, the nanocomposite was calcined. The decomposition of PAN during calcination resulted in the formation of HTNF. The nanofibers were characterized by FESEM, TGA and XRD. The characterization revealed hollow nanofibers structure with diameter of 200–250 nm. XRD analysis showed that the nanofibers had mixed crystalline phase, with 24.2% anatase and 75.8% rutile. The photocatalytic performance of HTNF were studied by evaluating the degradation of Bisphenol A (BPA) under UV light irradiation. In the photodegradation process, the effect of several parameters such as the initial concentration of BPA, pH of the solution and photocatalyst dosage were investigated. The optimum photocatalyst dosage, pH and initial BPA concentration were 0.75 g/L, pH 4.1 and 10 ppm BPA, respectively. Under these conditions, the photocatalytic performance of HTNF were found to be 97.3%, which was 12.6% higher than those of Degussa P25 TiO2. The degradation of BPA followed the pseudo-first-order kinetic model.
No abstract is provided for this article.
Nowadays, ceramic membrane developed from wastes has gained attention, especially towards water separation applications. With abundant and high silica content of fly ash, low cost ceramic membrane was successfully prepared via phase inversion and sintering technique. Prior to both phase inversion and sintering process, ceramic suspension was prepared at different loadings, ranging from 40wt% to 50 wt% fly ash and subsequently sintered at temperature ranging from 1150°C to 1350°C. By varying fly ash content and sintering temperature, the morphology, mechanical strength and phase transformation characteristics of the prepared membrane were affected. The characterisation of prepared membrane were investigated by using scanning electron microscopy, three-point bending test, and X-ray diffraction (XRD). The mechanical strength of the membrane increased with increasing fly ash loading (up to 45 %), however too much fly ash loading resulted in decrease of its mechanical strength probably due the presence of unburnt at higher fly ash contents. This unburnt carbon contributed to the vacant space during sintering process and had the tendency to increase formation of pores, simultaneously reduced its mechanical strength. In addition, the SEM results also illustrated a cross-sectional image of the membrane which had become more elastic with increasing fly ash loading and denser as sintering temperature gradually increased. In addition, increasing the fly ash loading likely discouraged the formation of desired finger-like structure. The XRD results however showed continuous presence of mullite with the increasing sintering temperature which contributed higher mechanical strength. The preliminary performance tests indicated that the optimum conditions to produce hollow fibre ceramic membrane from fly ash were at 45 wt % fly ash loading sintered at 1350°C and has a pure water flux of 131 L/m2h.
