This paper presents the work carried out to determine the morphology and mechanical properties of coating deposited layer that formed onto mild steel substrate using a new silicanizing method. The result shows that the coating silicanized layer consisting of FeSi, Fe2SiO4, FeSiO3 and SiO2 phase was successfully formed on the mild steel after subjecting to heat treatment process of 1000 °C for 4 hours. This layer of â��500I¼m thickness and also established that higher temperature and elongated deposition/adhesion time resulted an increase in SiO2 concentration on the substrate (mild steel). ©2006-2016 Asian Research Publishing Network (ARPN).
Nanocluster-like Pt nanoparticles/reduced graphene oxide nanocomposite catalyst (NC-PtNPs/RGO) was synthesized through a novel one-step process of chemical reduction-assisted hydrothermal reaction by using formic acid as reducing agent. The crystallinity, morphology and composition of the NC-PtNPs/RGO catalysts were extensively characterized. The as-prepared NC-PtNPs/RGO catalysts exhibited higher electro-catalytic activity towards methanol oxidation than carbon black (CB)/PtNPs catalyst and could be ascribed to the high dispersion of NC-Pt NPs with large electrochemical surface area, release more exposure of active sites by NC-PtNPs structure and synergy effect of RGO.
In general, alumina membranes have been extensively developed for protein separation and purification. Alumina membranes, which naturally feature a moderate hydrophilic character (contact angle of 40–50°) and the lowest cost among other oxide materials, are most suitable for these applications. Membrane fouling occurs due to the deposition and adsorption of proteins on the surface and pore walls of alumina membranes. This is one of the major issues that prevent the applicability of alumina membranes. Therefore, it is important to minimise membrane fouling by enhancing the hydrophilic character of the membranes as well as reducing interactions between proteins and the membranes surface. This review discusses the surface modification of alumina membranes in an effort to enhance the hydrophilic character of the membranes. Moreover, the introduction of graphene derivatives in modifying the hydrophilicity of alumina is also addressed. The superhydrophilic character of the alumina surface has a major influence on its anti-fouling and permeate flux properties, thus it improves the performance of the protein separation and purification processes.
The objective of this study is to investigate the spontaneous wettability response of alumina nanocomposites deposited onto hollow fibre ceramic based membrane. Bare membrane was fabricated from kaolin powder using a phase inversion technique and sintering process. The nanocomposites were synthesized by varying alumina nanoparticles composition via a sol-gel method. A dip-coating approach was used to deposit perfluorooctanoate (PFO) with alumina nanoparticles and poly (diallyl dimethylammonium chloride) (PDDA) on the active layer of the hydrolysed bare membrane to improve on the inefficiency of the conventional oil/water separation materials and easy fouling of the bare ceramic membrane. Both the bare membrane and coated membrane were characterized using scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM) and contact angle measurement. The performance of the membrane was tested for oil rejection and oil flux. The results suggest that higher sintering temperature improves the flexural strength of the bare membrane. The oil flux performance showed a decrease from 37.02 L/m2 h to 2.50 L/m2 h when the loadings of alumina nanocomposites (PDADMAC-Al2O3/PFO, PAP) coated onto the bare membrane was increased from 0.1 wt. to 0.6 wt., and in comparison, the oil rejection performance revealed an increase in the oil repellence from 80 to 98%. The oil contact angle was obtained at 125° after the chemical stability test in an acidic medium. The cogent mechanism of oleophobic and hydrophilic character of the coated membrane can be ascribed to the nano-scale hierarchical structure, as a result of alumina intercalated on the PFO. Alumina nanocomposite provides an excellent surface-coating material for ceramic-based hollow fibre membrane for oil-water separation to address the needs of wastewater industries.
Background Heavy metals in water pose grave risks to human health and the environment, necessitating the development of cost-effective and sustainable materials to combat heavy metal pollution in water. Natural and waste-based materials have received exceptional attention among researchers in removing heavy metals. Methods The efficient hydroxyapatite (HAp) and its composites have been utilized as adsorbents and membrane materials for the efficient elimination of heavy metals from wastewater, capitalizing on their low cost, eco-friendliness, thermal stability, and efficiency. Significant findings The review commences with a brief highlight and comparison of methods of heavy metal removal. Then, it delves into HAp properties, synthesis methods, and the influence of preparation conditions on HAp characteristics. The paper evaluates heavy metal adsorption in terms of equilibrium conditions, isotherms, and kinetics. While adsorption is effective for heavy metal removal, it can be labor-intensive for regenerating adsorbents and costly for large-scale applications. Therefore, the paper discusses the potential of HAp-based membranes fabricated via electrospinning and phase inversion techniques. It explores the characteristics and heavy metal removal performance of HAp membranes. In conclusion, the review discusses limitations and future directions for HAp-based membranes. This article serves as a valuable resource for understanding the capabilities of HAp-based adsorbents and membranes for sustainable heavy metal removal.
The research and development of the adsorptive membrane has received great attention due to its ability to perform high separation for heavy metals removal from wastewater. Adsorptive membrane integrates the adsorption and filtration mechanism in a single separation process. Several natural materials such as chitosan, hydroxyapatite, and cellulose can be used to fabricate the adsorptive membrane and thus, might reduce the fabrication cost. Furthermore, the materials can be easily obtained with facile techniques. Many papers have been published and showed the effectiveness of heavy metals removal with adsorptive membrane. In addition, there are several techniques have been used to fabricate the adsorptive membrane. Despite the effectiveness of heavy metal removal, the studies continue to enhance the antifouling properties and to increase the adsorption capacity of the membrane. Adsorbent materials such as titanium oxide (TiO2) and chitosan are discovered to exhibit excellent antifouling properties with higher thermal resistance and adsorption capacity. The antifouling properties are attributed to the enhanced and uniform hydrophilicity of the membrane. Thus, this review deliberates the recent progress of the adsorptive membranes in terms of the materials, fabrication methods, and performance.
Zeolites are microporous crystalline alumina-silicate materials, widely used as catalysts, ion exchangers and adsorbents due to their chemical structure and surface properties. The unique properties of zeolite such as high adsorption capacity and cation exchange make it interesting to be used as a support material. This review article presents the details of various researches of zeolite used as photocatalyst in photocatalytic application. The modifications of zeolite using several methods are described in details for photocatalytic enhancement. The effect of zeolite nanoparticles in membrane fabrication also provided in this article. Furthermore, the efficiency of zeolite used as adsorbents and photocatalyst in the photocatalytic application also presented.
A significant drawback of the traditional photocatalysts such as titanium dioxide (TiO2) is their inability to absorb visible light from the solar spectrum due to their wide band gap energy. They are only photoactive in the ultraviolet (UV) region which is just a little fraction of the solar spectrum and could be harmful with much exposure to it. Due to its abundance in the solar spectrum, visible light needs to be harnessed for environmental applications. However, we lack visible light driven photocatalysts with long-lasting energy storage capacity for “round-the-clock photocatalytic” (RTCP) applications. For this reason, there is a growing need to find new photocatalysts that can mitigate these bottlenecks. It is evident from some carefully selected published articles (1976–2021) that tungsten oxide (WO3) and its composites have attracted popularity in recent years because of its outstanding properties and particularly its smaller band gap energy of 2.8 eV. However, pristine WO3 is limited due to relatively low energy density and smaller specific surface area. These drawbacks can be addressed by developing various WO3 – based materials to improve their performance. This paper reviews and discusses their recent development in surface advancement, morphology control, modification of nanostructured WO3 and its composites, and their RTCP energy storage for photocatalytic activities in visible light and the dark for environmental applications. Specific aspects focused on its nature, structure, properties, synthesis, coatings, deposition, approaches at modifying and enhancing its visible light photoactivity for enhanced performance and energy storage potential.
