Publications

Carbon dioxide capture using a superhydrophobic ceramic hollow fibre membrane for gas-liquid contacting process

This work initiates the development of clean technology in carbon dioxide (CO2) capture using ceramic membrane inspired by gas–liquid contacting system. A low cost, high performance superhydrophobic kaolin-alumina hollow fibre membrane was prepared via phase inversion-based extrusion and sintering techniques, followed by a grafting with fluoroalkylsilane (FAS). The membrane was characterized by scanning electron microscopy (SEM), gas permeation test, contact angle, wetting resistance, X-ray photoemission spectroscopy (XPS), X-ray diffraction (XRD) and thermal gravimetric analysis (TGA). The fabricated membrane was highly porous, thus increasing the gas permeation rate. By surface modification, the membrane contact angle was increased from 0° to 142°. In fact, wettability resistance of the membrane was also improved. The membrane was subsequently applied in membrane contactor for carbon dioxide (CO2) absorption. The CO2 absorption flux as high as 0.18 mol m−2 s−1 was achieved at the liquid flow rate of 100 mL min−1 which was far above the fluxes of some commercial and in-house made polymeric and ceramic membranes. In conclusion, the modified kaolin-alumina hollow fibre membrane with the superhydrophobic surface, high permeance, and absorption flux is suitable for CO2 post-combustion capture, due to its outstanding chemical and thermal stabilities.

<scp>Sol‐gel</scp> based copper metallic layer as external anode for microtubular solid oxide fuel cell

Solid oxide fuel cell (SOFC) performance depends greatly on the anode conductivity, which in traditional nickel-yttria stabilized zirconia (Ni-YSZ) anode is determined by the Ni content that is infamous for its coking problem under hydrocarbon fuel. Without the use of high content of Ni, anode conductivity can be elevated by adding an external metal layer on top of the anode. In this study, we present the incorporation of copper (Cu) metal layer on top of the anode of micro-tubular SOFC by applying a modified sol-gel method using syringe deposition technique at various chemical compositions and deposition cycles. Cu sol was found best to be made up of 2:1:8 ratio of Cu: citric acid: ethylene glycol, with 1.36 μm metal layer formed at 5 deposition cycle, and no obvious increase in thickness after the fifth cycle. The Cu layer elevated the conductivity by 1010 times compared to the uncoated anode. However, the coated layer also reduced the gas permeability by 10 times in the anode, which resulted from the blocking of a nano-sized pore in the anode, rather than the micron size pore. This blocking can be resolved by increasing the amount of micron-sized pore by using pore former during anode fabrication. From electrochemical impedance spectroscopy (EIS), Cu coating reduced the ohmic resistance (Rohm) and charge transfer resistance (Rct). From the current-voltage curve, the maximum power density (MPD) was found to increase linearly with the increase of the Cu coating cycle, but the value is almost stagnant at 2.3 to 2.5 mW cm−2 when the coating cycle of more than 4 was employed. This suggests that anode gas permeation plays an important role in anode conductivity. The findings from this study suggested that 5 deposition cycle shows to be the optimal coating layer required to achieve the percolation threshold without unnecessary loss in permeability.

A comprehensive study on the surface chemistry of particulate matter collected from Jeddah, Saudi Arabia

No abstract is provided for this article.

Promoting sustainable cleaner production paradigms in palm oil fuel ash as an eco-friendly cementitious material: A critical analysis

Long term goals need to be set to promote the country’s circular economy (CE) as well as the cleaner environment by recycling waste materials into useful products. In pursuit of controlling environmental threats of carbon-based industrial wastes, different preprocessing techniques for their conversion into other value-added materials are being put in use. This review targets the purposeful utilization of massive amount of palm oil fuel ash (POFA), generated as a waste from power plants of palm oil processing mills in the major palm oil-producing countries. Currently, unrestrained disposal of POFA captures not only precious land but also creates environmental threats and health-related issues. Present work is an attempt to establish a sustainable cleaner production (SCP) system instead of unmanaged POFA disposal. Major palm oil producer countries should address the emerging issues of POFA related unsafe environment, energy consumption and landfill spaces by adopting reuse, reduce and recycle principles. Technically, this review also focuses on the use of POFA as a promising cementitious material in concrete production. It also maps the importance of POFA in concrete production as a cement replacement by presenting various state-of-the-art chemical reactions, mode of action of POFA for its pozzolanic reactivity in cement compositions and associated technical, environmental, and economic benefits. This will provide an alternative option and a sustainable solution for the global construction industry. It is conclusively evident from an extensive literature survey of 463 published results from last 26 years that POFA can be effectively used in concrete production to replace cement without compromising on its strength, performance, and durability. Based on the till that research work on POFA applications in the cement industry and other multiple areas, a circular economic model has been presented to support the concept of zero waste and SCP. It will stimulate the technical persons and decision-makers to make policies and strategies that can spotlight the effective use of POFA in multiple applications, primarily focusing on concrete production not only for curtailing the land and water pollution but also acquiring economic benefits.

Fabrication and characterization of robust zirconia-kaolin hollow fiber membrane: Alkaline dissolution study in ammonia solution

Kaolin has been found to be a more economical alternative in ceramic hollow membrane fabrication compared to alumina, silica, and zirconia despite having similar properties. However, it was discovered that apart from having high mechanical strength and the ability to withstand high operational temperature, the kaolin membrane has the tendency to dissolve in a high alkaline solution. Hence, in this study, zirconia (ZrO2) was imposed to kaolin suspension as co-starting material due to its stable hexagonal properties with kaolin to overcome this drawback. To study the dissolution property of the modified kaolin-based membrane, a phase inversion technique was used to fabricate zirconia-kaolin hollow fiber membrane (ZKHFM) followed by immersion in ammonium hydroxide (NH4OH) as an alkaline solution. Ammonia was aptly chosen for it being considered as one of the pollutants to be removed from wastewater. The mechanism, morphology and properties of the membrane were investigated in terms of sintering temperature, morphology, mechanical strength, pore size and porosity The results showed that ZKHFM with 10 wt% (ZK-10) with sintering temperature of 1,200 °C had the best performance in terms of having high mechanical strength (21MPa), excellent permeation flux (∼1,600 Lm2/h) and lowest dissolution (0.01 g dissolute) at pH 13, indicating the ability of ZKHFM to be used in alkaline solution.

Contributors

Advanced Membrane Technology for Textile Wastewater Treatment

No abstract is provided for this article.

Preparation and performance of PVDF-based nanocomposite membrane consisting of TiO2 nanofibers for organic pollutant decomposition in wastewater under UV irradiation

Polyvinylidene Fluoride (PVDF) nanocomposite membrane consisting of electrospun titanium dioxide (TiO2) nanofibers (PVDF/e-TiO2) was prepared by hot pressing the as-spun TiO2 nanofibers onto PVDF flat sheet membrane. The TiO2 nanofibers act as a photocatalyst to decompose organic pollutants present in wastewater under UV irradiation, while PVDF membrane acts as a support. The hot press technique was carried out by applying the operating temperatures at 100°C, 160°C and 180°C for 30min. The nanocomposite membrane was characterized by FESEM, EDX, contact angle measurement, DSC, and UV–Vis–NIR spectroscopy. The FESEM images and EDX analysis showed good adhesion and dispersion of TiO2 nanofibers in PVDF membrane. The hot-pressed PVDF/e-TiO2 membrane at lower temperature (100°C) (PVDF/e-TiO2-100) is more hydrophilic, higher pure water flux and has higher UV absorbance compared to the PVDF/e-TiO2-160 and PVDF/e-TiO2-180 membranes. The concentration of bisphenol A (BPA) in the feed solution was found to reduce with the degradation percentage of 63% to 85% after the PVDF/e-TiO2 nanocomposite membrane was treated with UV radiation. The results indicated that the introduction of TiO2 nanofibers in PVDF-based nanocomposite membrane via hot pressing indeed plays an important role towards enhancing the degradation and filtration of organic pollutants such as BPA.

Development of high-performance anode/electrolyte/cathode micro-tubular solid oxide fuel cell via phase inversion-based co-extrusion/co-sintering technique

A complete set of triple-layer (anode/electrolyte/cathode) hollow fiber for high temperature micro-tubular solid oxide fuel cell (MT-SOFC) consisting of nickel oxide (NiO) – yttria-stabilized zirconia (YSZ)/YSZ/lanthanum strontium manganite (LSM) – YSZ has been successfully fabricated in this study. A simplified fabrication technique of phase inversion-based co-extrusion/co-sintering has yielded a perfectly bounded sandwich structure with free-delamination and defect layers. The effect of co-sintering temperatures (1300 °C–1450 °C) on the morphologies, elemental distributions, electrolyte gas-tightness, mechanical strength, electrochemical performance and the impedance spectra test are well-inspected. The increase of co-sintering temperature has significant effects on the anode finger-like micro-channels shrinkage where the voids become very sharp-thin structure; and developing a thin gas-tight electrolyte layer. Whereas, rapid co-sintering rate (10 °C min−1) and large particle size of 3–5 μm (micron) of YSZ has hindered the formation of fully dense cathode layer resulting from higher co-sintering temperature. Correspondingly, with only 0.1116 Ωcm2 value of area-specific resistance (ASR), a maximum power density has increased from 0.34 W cm−2 to 0.75 W cm−2 with 1.05 V OCV at 700 °C when the co-sintering temperature ranging from 1400 °C to 1450 °C; which comparable with single-layer counterpart.

Affordability Under Siege: Intersecting Barriers to Home Ownership for Johor&amp;#8217;s Civil Servants

Performance of polysulfone hollow fiber membranes encompassing ZIF-8, SiO2/ZIF-8, and amine-modified SiO2/ZIF-8 nanofillers for CO2/CH4 and CO2/N2 gas separation

High tunable properties of metal–organic frameworks (MOFs) allows different modifications to be used for distinct applications. Zeolitic imidazolate frameworks-8 or ZIF-8 are hybrid organic–inorganic porous materials that have shown great potential in membrane-based gas separations. In our study, SiO2/ZIF-8 (S/ZIF-8) nanofiller was synthesized via a facile one-step strategy. Furthermore, the S/ZIF-8 nanofiller was subjected to amine modification using an ammonium hydroxide solution. X-ray photoelectron spectroscopy (XPS) analysis confirms the strong binding of amine and SiO2 on ZIF-8 nanofillers. The synthesized ZIF-8, S/ZIF-8, and amine-modified S/ZIF-8 (A@S/ZIF-8) of 0.5 wt% were incorporated into the polysulfone (PSf) matrix, and the hollow fiber mixed matrix membranes (MMMs) were fabricated using dry–wet phase inversion technique. The inclusion of an amine group in the S/ZIF-8 nanofillers enhances the interaction between the nanofillers and PSf matrices, thus improving the CO2/CH4 and CO2/N2 separation performances. The fabricated membranes were morphologically characterized by Scanning electron microscope (SEM), Brunauer–Emmett–Teller (BET) surface area, and the pore size distribution. It is noteworthy that the BET surface area was enhanced with nanofillers addition and significantly increased gas separation performance. The fabricated asymmetric hollow fiber MMMs were further studied for gas permeation experiments for CO2, N2, and CH4. PSf with A@S/ZIF-8 MMMs showed the best performance as observed from the Robeson upper bound limit, CO2 permeability of 4.25 barrer with the improvements in CO2/N2 and CO2/CH4 selectivities of 89.75 and 61.46% respectively, compared with neat PSf membrane. The enhanced permselectivity of PSf–A@S/ZIF-8 membranes is explained by CO2-facilitated transport, where the high CO2 affinity of the amine group allows the selective transport of CO2 rather than CH4 and N2.

Visible-Light-Driven Photocatalytic N-Doped TiO2 for Degradation of Bisphenol A (BPA) and Reactive Black 5 (RB5) Dye

No abstract is provided for this article.

Enhanced CO2/CH4 separation using amine-modified ZIF-8 mixed matrix membranes

Amine-modified mixed matrix membranes (A-Ms) have been developed with improved anti-plasticization behavior at high pressure for natural gas purification. Neat polysulfone (PSf) hollow fiber membranes and amine-modified zeolitic imidazole framework-8 (A-ZIF-8) blended PSf membranes have been prepared with the aim of purifying natural gas. The fabricated membranes have been evaluated using gas performance tests, thermogravimetric analysis (TGA), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and field emission scanning electron microscopy (FESEM). When tested using pure gases, the membrane with 0.25 wt percent A-ZIF-8 demonstrated a substantial enhancement in CO2/CH4 selectivity of 50 %, 72 %, and 69 % when compared to the neat membrane, and an increase of 33 %, 78 %, and 77 % in CO2/CH4 selectivity compared to the virgin ZIF-8-based membrane at feed pressures of 6, 8, and 10 bar (g), respectively. Subsequently, the separation performance has decreased due to the increased A-ZIF-8 loading. Improved anti-plasticization behavior at high feed pressure is further demonstrated by the exceptional gas separation performance at low loading of A-ZIF-8 nanoparticles. The promising results showed the potential use of A-ZIF-8 for natural gas purification.

Fabrication of Dual Layer Hollow Fibre Membranes for Photocatalytic Degradation of Organic Pollutants

In recent years, the membrane photocatalytic reactor (MPR) systems have attracted much attention due to their promising function in treating organic pollutant and filtering clean water.Suspended photocatalyst titanium dioxide (TiO 2 ) particle always become a problematic in hybrid MPR system due to membrane fouling and TiO 2 loss.In the past few years, considerable attention has been paid to immobilize TiO 2 nanoparticles on various materials.Since ultraviolet (UV) source and TiO 2 are required for the photocatalytic reaction, thus, it is crucial to immobilize high concentration of TiO 2 on the outer surface of the polymeric membrane support.By using co-extrusion approach, a dual layer hollow fibre (DLHF) membrane was fabricated.The effect of additives on the dope polymer solutions and membrane morphologies of DLHF were investigated using of scanning electron microscopy (SEM).The SEM results showed that DLHF membranes have a good adhesion between layers with no delamination.

The Functionalization Study of PVDF/TiO2 Hollow Fibre Membranes Under Vacuum Calcination Exposure

In this study, polyvinylidene fluoride (PVDF) hollow fibre membrane was modified by adding TiO 2 . TiO 2 presence affects the membrane structure becomes more less hydrophobic which makes the membrane less fouling. Membranes were made via dry-wet spinning method and calcined under vacuum condition by furnace (100, 300, and 500 °C). Besides, PVDF-TiO 2 uncalcined membrane were also prepared as comparison to investigated the effect of calcination on hollow fibre membrane’s functional groups. Fourier Transform Infrared (FT-IR) spectra indicated that all PVDF-TiO 2 membranes have bands of OH in the TiO 2 at ∼1600 cm −1 . Peaks of α-phase PVDF crystals appeared at ∼876, ∼876, and ∼872 cm −1 for uncalcined, 100 and 300 °C, while for 500 °C the PVDF peak only shows at 874 cm −1 . The peaks at ∼1200 cm −1 represent CF 2 groups. Peaks at ∼1400 cm −1 assigned to CH 2 groups, but it does not observed for 500 °C. Deconvolution by Fityk software that shows calcination using vacuum condition gives the compounds gradually decomposes. At high temperature calcination lead the CH 2 peak extremely lost.

Functional ceramic hollow fibre membranes for catalytic membrane reactors and solid oxide fuel cells

This chapter introduces major developments and use of functional ceramic hollow fibre membranes, that is a membrane design consisting of a dense outer layer for separation supported on a highly porous inner catalytic substrate layer, for energy utilization in methane conversion and micro-tubular solid oxide fuel cells (SOFCs). The advantages of the dual-layer hollow fibre membrane design and the single-step co-extrusion and co-sintering process employed to achieve this membrane design are addressed. The key factors that affect the fabrication and performance of the developed membranes are discussed and future technology challenges are also outlined.

Development and implementations of integrated osmosis system

The development and implementations of an integrated osmosis system (IOS) was discussed in this chapter. An IOS is comprised of the sequential stages of forward osmosis (FO), reverse osmosis (RO), and the related membranes. Performance and cost-effectiveness that cannot be easily achieved individually with the component systems can be achieved with IOS by optimally placing and using the desired properties of each membrane. IOS provides high diffusive and osmotic permeability, high rejection, low power consumption, and high mass transfer via the manipulation of convection, advection and diffusion, low concentration polarization gradients, low reverse salt flux, and effective restoration of performance after cleaning fouled membranes. The benefits of IOS include better permeate recovery and decreased volume of waste concentrate from RO processes or other elevated osmotic pressure solutions. The process of integrated osmosis first involves the use of a nanofiltration process to selectively harvest the solutes to achieve permeates with a reduced osmotic pressure. Then, the FO process is initialized to dewater the lowered osmotic pressure permeate in order to generate a dilute draw solution that serves as feed to the RO process. For the FO proses, RO permeate provides freshwater while the concentrate provides the draw solution. At the end of this chapter, an attempt is also made to show the research development and future direction of IOS, through hybrid membrane technology. The potential of the integrated systems to solve the world’s water crisis is more advantageous and economical compared to the individual systems.

Structural, optical, and photocatalytic investigation of nickel oxide@graphene oxide nanocomposite thin films by RF magnetron sputtering

No abstract is provided for this article.