Ceramic hollow fibre membranes derived from natural resources for treatment of arsenic-contaminated water via membrane distillation

Arsenic is regarded as one of the most toxic heavy metals and the largest mass poisoning material in the world. Recently, membrane distillation (MD) using hydrophobic membranes has been a promising technology for arsenic removal in water. While polymeric membranes are known to show drawbacks such as low thermal and chemical resistivity, similarly, commercial ceramic membrane from alumina that is extremely expensive. Therefore, the development of cost effective ceramic membranes from natural materials have grown inexorably to solve some of the underlying issues. In this work, hydrophobic ceramic hollow fibre membranes (CHFM) derived from natural resources (kaolin, rice husk waste and cow bone waste) were developed via phase inversion and sintering technique and modified through fluoroalkylsilane grafting. At the beginning of the study, characterization on chosen natural resources (kaolin, silica based rice husk ash and hydroxyapatite based cow bone) were performed. The prepared membranes were characterized and modified with 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane and ethanol solution for 24 hours with respect to their morphological structure, surface roughness, wettability behaviour, pore size distribution and porosity. The results revealed that the modification process successfully turned the CHFM from hydrophilic to hydrophobic with contact angle value of 145°, 157°, 161° and 170° for membranes prepared from kaolin, amorphous silica, crystalline silica and hydroxyapatite, respectively. Afterwards, the prepared CHFM were tested towards synthetic arsenic wastewater by varying direct contact membrane distillation (DCMD) parameters such as arsenic pH, arsenic concentration, and arsenic-feed temperature. It was found that CHFM prepared from kaolin (KHFM) prepared at kaolin content of 37.5 wt.% and sintered at 1300°C showed the best performance with 100% rejection of arsenite [As(III)] and arsenate [As(V)]) towards arsenic removal via DCMD system. Nevertheless, the last part of the study is treating the arsenic-contaminated water collected from Sungai Pengorak, Malaysia using the best membrane that induced 100% arsenic removal via DCMD system. When comparing the performance of the prepared membrane in this study with nanofiltration and reverse osmosis membranes, it was found that the newly-developed KHFM showed excellence performance in treating arsenic-contaminated water with 100% arsenic rejection and stable flux of 23kg/m2h. It is worth mentioning that no membrane fouling was observed in the prepared KHFM for 72 hours of operation in this study compared to polymeric membrane

Consumer Behaviour Towards the Reduction of Single-Use Plastic Among the Residents in Jelutong, Penang

 Malaysia was ranked eighth out of the top 20 countries in terms of mismanaged plastic waste. High consumption of single-use plastic by consumers was the largest source of this issue. It is noticeably that consumers’ behaviours play a significant role to reduce the usage of single-use plastic. Hence, this research aims to identify the consumer behaviours of using single-use plastics in daily life among the residents in Jelutong, to determine the factors that influence the behavioural intention of single-use plastics reduction among the residents in Jelutong and, to identify the most significant factor that influence the behavioural intention of single-use plastics reduction among the residents in Jelutong. This research was carry out by using the Theory of Planned Behaviour (TPB). A Quantitative method which is using online questionnaire was employed and the total samples were 382 residents in Jelutong, Penang. All of the data were analysed using descriptive analysis and regression analysis through Statistical Packages for the Social Sciences (SPSS) software. The results show a positive relationship between the variable of attitude and subjective norm. Meanwhile, attitude is the most significant factor that influence the residents’ behavioural intention against lower plastic consumption. Thus, the findings of this study could provide usefulinformation that enable policymakers to implement effective strategies and address the plastic waste pollution to ensure future environmental sustainability

Characteristic properties of ceramic membrane derived from fly ash with different loadings and sintering temperature

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

Novel superhydrophobic and superoleophilic sugarcane green ceramic hollow fibre membrane as hybrid oil sorbent-separator of real oil and water mixture

The frequent oil spill accidents in nowadays has aroused great attention all over the world. Superhydrophobic and superoleophilic grafted on various substrates have attracted much attention to treat oil and water mixture because of their unique performance that can effectively separate oil and water mixture. At the same time, ceramic membrane also shows potential substrates to be used in treating oil and water mixture. However, conventional ceramic membrane that made from alumina show drawbacks in term of its high cost production. Herein, we report a new ceramic membrane that derived from agricultural-sugarcane bagasse waste and modified into superhydrophobic and superoleophilic to act as hybrid oil sorbent and separator. In this study, we successfully treat three types of real oil and water mixture from palm oil mill effluent (POME), restaurant and car wash with oil rejection and flux up to 99% and 134 L/m2h, respectively. In summary, this work demonstrates a facile, economic and effective method to fabricate superhydrophobic and superoleophilic substrates for oil and water separation

Novel superhydrophobic and superoleophilic sugarcane green ceramic hollow fibre membrane as hybrid oil sorbent-separator of real oil and water mixture

The frequent oil spill accidents in nowadays has aroused great attention all over the world. Superhydrophobic and superoleophilic grafted on various substrates have attracted much attention to treat oil and water mixture because of their unique performance that can effectively separate oil and water mixture. At the same time, ceramic membrane also shows potential substrates to be used in treating oil and water mixture. However, conventional ceramic membrane that made from alumina show drawbacks in term of its high cost production. Herein, we report a new ceramic membrane that derived from agriculturalsugarcane bagasse waste and modified into superhydrophobic and superoleophilic to act as hybrid oil sorbent and separator. In this study, we successfully treat three types of real oil and water mixture from palm oil mill effluent (POME), restaurant and car wash with oil rejection and flux up to 99% and 134 L/m2 h, respectively. In summary, this work demonstrates a facile, economic and effective method to fabricate superhydrophobic and superoleophilic substartes for oil and water separation

Preliminary characterization of corn cob ash as an alternative material for ceramic hollow fiber membrane (CHFM/CCA)

Currently, exchanging trends in the expensive usage of ceramic materials such as alumina, zirconia etc. into economical ceramic raw sources have been extensively studied over the last decade for various technological applications. Despite the fact that this ceramic compound or elements offer a great performance and stability, especially at high temperature, the basic commercial price and higher sintering temperature of this compound which is a little bit higher have hindered the used of these materials. Thus interest in fabricating of bio-ceramic membrane using corn cob ash (CCA), an agricultural by product not only offered the development of new low cost materials but also able to enhance better properties and performance. The suitability of corn cob ash as an alternative material for ceramic hollow fiber membrane fabrication (CHFM/CCA) as a main substrate was investigated via combined phase inversion and sintering technique based on several controlled operating parameters. The effects of selected bore fluid (5, 10, 15 and 20 mL/min) and different sintering temperature (800 °C, 900 °C, 1000 °C, 1100 °C) towards membrane structure and properties were observed and studied. Interestingly, characterization analysis of the SEM morphology showed that the potential of the main constituents of corn cob ash which highly consisted of silica, alumina and calcium oxide are able to improve the properties of CHFM/CCA by lowering sintering temperature (1000 °C) as compared to the standard CHFM bodies which normally has sintering temperature higher than 1200 °C. Thus, the use of corn cob ash not only able to enhance ceramic properties but also able to reduce sintering temperature. Reduction in energy consumption with slightly reduced sintering temperature also will offer a better sustainable process through recycling abundant waste materials as well as emphasis on the green resources. With that respect, the bio-material of corn cob ash is capable to replace the commercial ceramic membrane materials for membrane applications by considering the availability of this agro waste product as the main crops in most countries in the world

The Optimization of RHS-polysulfone Membrane towards Operating Condition for Humic Acid Removal

This study investigates the effects of rice husk silica (RHS) as additive in the polysulfone membrane to enhance antifouling properties in membrane separation process. The performance (of what?) was evaluated in term of pure water flux (PWF), rejection and antifouling properties. The optimized of normalized flux (Jf /Jo) at different parameter in filtration (pH, ionic strength and tranmembrane-pressure) was carried out by using the response surface methodology (RSM). The results showed that the addition of 4 wt. % RHS give the highest flux at 300.50 L/m².hour (LMH). The highest rejection was found at 3 wt. % of RHS membrane with value 98% for UV254 and 96% for TOC. The optimal value of Jf/Jo was found at 0.62 with the condition of pH: 6.10, ionic strength: 0.05 mol/L and transmembrane-pressure: 2.67 bars. Optimize of RSM analysis from ANOVA also proved that the error of model is less than 0.05% which indicates that the model is significant

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

Modelling of transport mechanisms and drying shrinkage for multilayer ceramic membrane structure

In ceramic membrane preparation, the understanding of drying phenomena is very important to ensure no defects and failures that may present in the membrane layers. The combination of hygroscopic and non-hygroscopic multilayer systems that possess different properties is always associated with the failure ofthe consolidated structure of ceramics during the drying and sintering process. Hence, a two-dimensional mathematical model that coupled mass, heat, and gas transfer was employed to describe the drying process as a whole multilayer ceramic membranes structure. The finite element method was used to solve the model and computation was carried out using a Skyline solver to capture the highly nonlinear and transient process. This study emphasises on the evolution of transport variables during the drying that can be correlated to shrinkage mechanism. The side surface heating boundary was performed with a conclusion that hygroscopic materials have low drying rate due to the material characteristic which inherent higher water retention in a solid matrix. This characteristic also causes higher pore water pressure and gas pressure. The drying of hygroscopic layer has resulted in higher moisture gap which in turn increased the possibilities of cracking. The results obtained from this study enable the optimisation with respect to drying time and material selection thus significantly contributes to the energy saving as well as reducing the environmental effect via less waste energy loss