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Inorganic silica precursors, also known as alkoxysilanes, have been used commercially in many applications and synthetizations. However, it has been reported that these inorganic silicas can harm human health, causing stomach, bladder, and kidney failure, as well as death in the case of an acute inhalation. Due to this reason, organic silica from agricultural waste such as coconut husks, corncobs, sugarcane bagasse, rice husks, and bamboo leaves is being reviewed as an alternative source to replace the risky inorganic silica. This work discussed the extraction method, silica percentage obtained, and applications involving the use of organic silica, demonstrating that green waste can replace inorganic silica and provide good value to society. [ABSTRACT FROM AUTHOR]

Generally, rural areas can contain large amounts of organic and household wastes, which on average, is rarely managed well. Meanwhile, composting is a waste management method that decomposes organic waste biologically, thus contributing toward better waste management and environmental sustainability. However, exposure to more efficient waste management methods and the knowledge of the importance of composting are still low among rural communities. These communities also do not realise that composting has the added potential benefit of increasing household income. Therefore, this exploratory study was performed guided by two objectives, first to identify the critical success factors of composting practice for improving the economy and quality of life among rural communities, and second, to identify factors that hinder this composting practice. A quantitative approach was used for this purpose, where data were obtained through non-probability sampling from respondents located in 32 rural villages in the Kubang Pasu District of Kedah, Malaysia. The results of this study revealed that villagers living outside of city limits do not practice composting as part of their waste management. Among the barriers that were identified as preventing composting practice in these rural village communities, were the lack of knowledge, awareness, and interest in composting. However, some of these respondents indicated that they were aware of composting through television, radio, social media, newspapers, and from various programmes organised by certain organisations. In conclusion, this study has provided information as a guide to stakeholders for them to act by further educating rural communities about composting, perhaps highlighting more the potential benefits of earning a side income through the adoption of composting practices by producing and selling compost fertilisers. [ABSTRACT FROM AUTHOR]

Zeolite A was successfully synthesized using Perak kaolin which acts as the main source of silica and alumina. The process of beneficiation was conducted on raw kaolin to remove the impurities that existed in natural kaolin and also to increase the physical and chemical characteristic of kaolin. The kaolin was continued to be heated in the furnace with the temperature of 6000C for 4 h which described as a metakaolinization process that transformed it into the amorphous stage. The raw kaolin was characterized by XRD, FESEM, FTIR, PSA, TGA, while metakaolin by XRD, FESEM and FTIR. The mixture of zeolite A was achieved by adding the metakaolin into sodium hydroxide (NaOH) solution without adding other sources of silica and alumina. The solution mixture was stirred for 24 h before undergoing the process of hydrothermal synthesis. Two optimum conditions were studied for Zeolite A synthesizing, which were different molarity of sodium hydroxide and crystallizations time during the hydrothermal process. The successful synthesis of Zeolite A was then characterized by XRD, FESEM, FTIR, PSA, and BET surface area. The BET surface area of Zeolite-A is higher, 5.26 m2/g, compared to natural zeolite, 2.9 m2/g. As demonstrated in this work, Perak kaolin which was successfully synthesized into Zeolite-A with 2 M NaOH and 12-h crystallization time, gave a higher crystallinity percentage, 72.97%. The results obtained revealed that formation The of zeolite A has been highly affected by the NaOH molarity and crystallization time used in the combination of reactions. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Recent advancement of polymer mixed matrix membrane (MMM) embedded with either inorganic or organic additive have gained much interest among researchers. In this work, flower-like TiO2 (FLT) additive with a high surface area was synthesized using hydrothermal method. Generally, a high surface area indirectly provides more active sides that improve additive functionality. Thus, the effect of unique structural with different concentrations of FLT as an additive towards polysulfone (PSf) MMM was investigated in terms of characteristics and performance. The results of cross-sectional morphology, additive distribution, hydrophilicity, and surface roughness show that the polymer MMM was significantly improved with better surface adherence and well-dispersed of FLT inside the membrane structure. This improvement increased membrane performances such as permeation (from 61.34 L/m2h for neat PSf membrane and 137.81 L/m2h for 3 wt% PSf-ST MMM to 3 wt% 155.46 L/m2h for PSf-FLT MMM), rejection (above 97% for PSf-FLT MMM), antibacterial (261.24 cm2 and 145.13 cm2 for 3 wt% PSf-ST and 3 wt% PSf-FLT, respectively) and antifouling properties (with 85.62% FRR for 3 wt% PSf-FLT compared to 74.10% FRR for 3 wt% PSf-ST). Different shapes and geometries of FLT solved the drawbacks of ST, especially in eliminating the agglomeration effect by providing more adherence surface area. [ABSTRACT FROM AUTHOR]

The membrane contactor system is one of the most important technologies to trap CO2 from natural gas. To apply this technology, hollow fibre membranes with a superhydrophobic surface must be used, where membranes were prepared from kaolin clay through the phase inversion/sintering technique and modified by three types of fluoroalkylsilane (FAS) molecules (C6, C8, C10) at different immersion times (6, 24, 48,72 h) to capture CO2 from natural gas via contacting the gas-liquid system. The kaolin was chosen due to its abundant availability at an affordable price as well as the high amount of the hydroxyl (OH) group in the surface which easily reacts with FAS during the grafting process. Superhydrophobicity was distinguished by Fourier transform infrared (FTIR), scanning electron microscopy (SEM), liquid entry pressure of water (LEPw) measurement, and contact angle (CA). The lowest pore size of the grafted membrane obtained for C8 was about 1.32 μm; it was considered the perfect target for high membrane resistance. The chosen superhydrophobic kaolin membrane was tested for carbon dioxide (CO2) capture via the membrane contactor system. With increasing time of immersion, the hydrophobicity phenomena rose gradually until superhydrophobicity property was obtained. Forty-eight hours was proven as sufficient time to obtain the desired superhydrophobicity property to avoid wetting pores of the membranes. Besides, the perfect type of FAS for separating CO2 was C8 based on the sufficient LEPw and contact angle. The reduction of pH was observed after testing the performance of using a membrane contactor to separate CO2 by using water as absorbent where pH value decreased from 6.6 to 4.3 within 1 h, which concludes the success of the gas-liquid system into removing CO2 from natural gas. [ABSTRACT FROM AUTHOR]

Low-cost green ceramic hollow fiber membranes (CHFM) were successfully designed and fabricated from the industrial waste ash, palm oil fuel ash (POFA) via phase inversion-based extrusion/sintering techniques for water filtration application. The extrusion process parameters such as suspension viscosity, air gap distance, and bore fluid flow rate were systematically explored to produce the membrane with desired morphology. A high suspension viscosity would result in a small macro-voids structure. Moreover, a high air gap distance would induce fiber with long macro-voids structure, while a low bore fluid flow rate would lead to the formation of distorted lumen structure. The effect of sintering temperature toward CHFM was also studied and characterized. An increase in the sintering temperature improved the membrane bending strength, but also afflicted the flux performance due to lower porosity and higher tortuosity. The developed membranes achieved excellent bending strengths of >75 MPa at lower sintering temperatures than the alternative ceramic counterparts, due to the formation of the eutectic liquid during sintering. The relatively low sintering temperature of POFA-derived CHFMs could reduce the energy consumption and sintering duration, which could be more economically attractive than their ceramic counterparts, thus benefiting industrial users. [ABSTRACT FROM AUTHOR]

Membrane distillation (MD) is a thermally driven membranous process and in the recent years, it has received increasing attention in desalination. Generally, polymeric membranes have dominated the MD studies due to their intrinsic hydrophobic properties and high availability. On the other hand, the development of ceramic membranes for MD desalination is developing, gradually replacing their polymeric counterparts due to superior properties in terms of thermal, chemical and mechanical stabilities, as well as potentially longer service terms. This review describes and evaluates the fabrication methods of ceramic membranes as well as discusses the latest discoveries of ceramic membranes for MD desalination. Despite outstanding properties, the efforts in developing ceramic membranes as a replacement for polymeric membranes in MD desalination are meeting challenges and obstacles; hence, in the last part of this article, the current challenges and future research opportunities of ceramic membrane development will also be addressed. [ABSTRACT FROM AUTHOR]

Solid oxide fuel cell (SOFC) is an attractive device that can convert chemical into energy. Recently, the triple layer hollow fiber (TLHF) opens up a new discovery of higher power output. This study investigates the fabrication of TLHF in solid oxide fuel cell consisting anode/anode functional layer (AFL)/electrolyte (NiO-YSZ/NiO-YSZ/YSZ) via single-step phase inversion-based co-extrusion combined with co-sintering technique using methane as fuel. TLHF formed sandwich-like structure that corresponds to the anode and AFL with dense electrolyte. Initially, the open circuit voltage (OCV) was 1.1 V, after 90 min, the OCV dropped to 0.2 V due to the carbon deposits that caused poisoning. Meanwhile, the power density also reduces from 0.8 to 0.33 Wcm−2. SEM image carbon shows the carbon deposited causing crack and reached electrolyte layer. TEM of the Ni catalyst indicates there are multilayer of graphite exhibit at the Ni particle courtesy of the carbon deposits. The results showed the graphite causing the performance to decrease which is corresponding to the usage of methane as fuel. [ABSTRACT FROM AUTHOR]

In this study, the effects of two fuel types, i.e., hydrogen and methane on the electrochemical performance of the co-extruded triple layer hollow fiber, were systemically studied. The triple layer hollow fiber consisted of electrolyte/active functional layer (AFL)/anode was fabricated by single-step phase-inversion-based co-extrusion technique prior to the sintering process at temperature range of 1400 to 1500 °C. The hollow fibers were characterized by three-point bending test, gas tightness test, and scanning electron microscope (SEM). The electrochemical performance test was carried out at temperatures of 700–800 °C by flowing fuel at 20 ml/min. Based on the results attained, the gas tightness and bending test are improved by the increase of sintering temperature. SEM results show that the finger-like morphology length around 100 μm is obtained. In addition, the AFL layer located in the middle layer of the hollow fiber has its own finger like which forms sandwich-like structure with the anode layer. The open circuit voltage is recorded at 1.05 V with the highest power density obtained at 0.6 W cm−2 by using hydrogen. By changing the fuel into methane gas, the highest power density is achieved at 0.8 W cm−2. This is due to the methane that carries more hydrogen molecule. This indicates that the methane fuel can be utilized in hollow fiber SOFC systems. [ABSTRACT FROM AUTHOR]

Key lime, watermelon, and kiwifruit juices were successfully clarified by using a novel high strength and antifouling metakaolin-based ceramic membranes prepared via combination of phase inversion and sintering technique. The fabricated membrane was characterized by utilizing scanning electron microscopy (SEM) analysis, three-point bending strength, juice permeation, and fouling behavior analysis. In this work, the fouling behavior of the membrane was studied using Darcy's law for cross-flow filtration system. Analysis of the fouling mechanism revealed that the membranes' fouling was most influenced by the cake filtration mechanism and can be solved easily by applying high operating pressure. Membranes prepared at a sintering temperature of 1300 °C were found to be optimum membranes for juice clarification as it possessed excellent mechanical strength (176.8 MPa) and pure water flux of 273 L/m2 h at 500 kPa. Interestingly, it was also found that the membrane could endure high operating pressure up to 700 kPa, which consequently solved the fouling issue. Thereby, the precious juice properties, such as total suspended solid (TSS), pH, acidity, and density for all juices, were found to be almost unaffected. [ABSTRACT FROM AUTHOR]

In this study, low cost ceramic supports were prepared from kaolin via phase inversion technique with two kaolin particle sizes, which are 0.04-0.6 μm (denoted as type A) and 10-15 μm (denoted as type B), at different kaolin contents ranging from 14 to 39 wt.%, sintered at 1200 °C. The effect of kaolin particle sizes as well as kaolin contents on membrane structure, pore size distribution, porosity, mechanical strength, surface roughness and gas permeation of the support were investigated. The support was prepared using kaolin type A induced asymmetric structure by combining macroporous voids and sponge-like structure in the support with pore size of 0.38 μm and 1.05 μm, respectively, and exhibited ideal porosity (27.7%), great mechanical strength (98.9 MPa) and excellent gas permeation. Preliminary study shows that the kaolin ceramic support in this work is potential to gas separation application at lower cost. [ABSTRACT FROM AUTHOR]