Purpose Regular monitoring of bacteria, especially Escherichia coli, in wastewater is crucial to ensure the maintenance of public health. Amperometric detection proves to be a fast, sensitive and economically viable solution for E. coli enumeration. This paper reported a prototype amperometric sensor based on PANI-ZnO-NiO nanocomposite thin films prepared by sol–gel method and irradiated with gamma ray. The purpose of this study is to investigate the sensor performance of PANI-ZnO-NiO nanocomposite thin films to detect E. coli in water. Design/methodology/approach The films were varied with different compositions of ZnO and NiO by using the formula PANI-(ZnO)1-x-(NiO)x, with x = 0.2, 0.4, 0.6 and 0.8. PANI-ZnO-NiO nanocomposite thin films were characterized by using X-ray diffraction (XRD) and atomic force microscopy (AFM) to study the crystallinity and surface morphology of the films. The sensor performance was conducted using the current–voltage (I-V) measurement by testing the films in clean water and E. coli solution. Findings XRD diffractograms show the peaks of ZnO (1 0 0) and NiO (1 0 2). AFM analysis shows the surface roughness, and the grain size of PANI-ZnO-NiO thin films decreases when the concentration ratios of NiO increased. I-V curves show the difference in current flow, where the current in E. coli solution is higher than the clean water. Originality/value PANI-(ZnO)1-x-(NiO)x nanocomposite thin film with the highest concentration of ZnO performed the highest sensitivity among the other concentrations, which can be used to indicate the presence of E. coli bacteria in water.
The objective of this study was to fabricate dual‐layer hollow fiber as a microreactor for potential syngas production via phase inversion‐based co‐extrusion/cosintering process. As the main challenge of phase inversion is the difficulty to obtain defect‐free fiber, this work focuses on the effect of the fabrication parameters, that is, nonsolvent content, sintering temperature and outer‐layer extrusion rate, on the macrostructure of the produced hollow fiber. SEM images confirm that the addition of nonsolvent has successfully minimized the finger‐like formation. At high sintering temperature, more dense hollow fiber was formed while outer‐layer extrusion rate affects the outer layer thickness.
Microplastics (MPs), as emerging indoor contaminants, have garnered attention due to their ubiquity and unresolved implications for human health. These tiny particles have permeated indoor air and water, leading to inevitable human exposure. Preliminary evidence suggests MP exposure could be linked to respiratory, gastrointestinal, and potentially other health issues, yet the full scope of their effects remains unclear. To map the overall landscape of this research field, a bibliometric analysis based on research articles retrieved from the Web of Science database was conducted. The study synthesizes the current state of knowledge and spotlights the innovative mitigation strategies proposed to curb indoor MP pollution. These strategies involve minimizing the MP emission from source, advancements in filtration technology, aimed at reducing the MP exposure. Furthermore, this research sheds light on cutting-edge methods for converting MP waste into value-added products. These innovative approaches not only promise to alleviate environmental burdens but also contribute to a more sustainable and circular economy by transforming waste into resources such as biofuels, construction materials, and batteries. Despite these strides, this study acknowledges the ongoing challenges, including the need for more efficient removal technologies and a deeper understanding of MPs' health impacts. Looking forward, the study underscores the necessity for further research to fill these knowledge gaps, particularly in the areas of long-term health outcomes and the development of standardized, reliable methodologies for MP detection and quantification in indoor settings. This comprehensive approach paves the way for future exploration and the development of robust solutions to the complex issue of microplastic pollution.
Fibre optic sensing technology has recently been hailed as a viable alternative for a real-time reservoir monitoring method. The aim of this study is to develop a robust and high-sensitivity polycarbonate optical fibre (PCPOF) sensor that can detect oil movement in porous media. To enhance the sensing capability of the Bragg sensor, partial removal of the cladding and deposition of APTES treated TiO2 on the sensing region was conducted. The cladding layer was removed using the chemical etching and the etching time was varied from 5 to 11 min. The best etching time was 9 min with a cladding thickness of ∼1.47 µm and increasing the etching time may result in damage to the fibre core. The nanoparticles were coated evenly to the sensing areas through a double dip-coating technique to ensure uniform distribution of TiO2. Sensor sensitivity was tested at 60 °C, 90 °C, and 120 °C. The sensitivity of the sensor was found to be more than 100 nm/RIU on average in different temperatures and the sensor was also capable to work at a temperature of 120 °C. Thus, the fabricated fibre optic sensor offers huge potential for real-time monitoring of reservoirs in oil and gas fields, which should be a very useful tool for engineers.
In this work, green silica-based ceramic hollow fiber membranes (CHFMs) derived from rice husk ash waste were successfully prepared via phase inversion and sintering technique. Prior to the fabrication, rice husk waste was converted into amorphous and crystalline silica-based rice husk ash (ARHA and CRHA). The surface of CHFMs could be easily modified to become hydrophobic by grafting with a fluoroalkylsilane (FAS) agent. The CHFMs were characterized before and after grafting using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), measurement of contact angle and liquid entry pressure of water (LEPw), and three-point bending test. The pore size and the porosity of the membrane surface were also evaluated using mercury intrusion porosimetry (MIP). Lotus-leaf structure formed at the surface of HFMs by grafting, leading to a high contact angle of >150°. Direct contact membrane distillation (DCMD) performance of membrane after grafting was conducted for 200 h using the synthetic seawater of various NaCl concentrations at different feed temperatures. The experimental results show that the permeate flux decreased with the increasing feed concentration, whereas it was enhanced with the increasing feed temperature. A high water flux of 38.2 kg/m2 h and salt rejection up to 99.9% were obtained by CHFM prepared from CRHA (CHFM/CRHA).
A porous hollow fibre ceramic membrane derived from a low-cost natural material (silica sand) and fabricated by combine phase inversion and sintering technique followed by fluoroalkylsilane (FAS17) grafting to improve its hydrophobicity is reported in this study. Prior to the subjection of the silica sand ceramic hollow fibre membrane (SSCHFM) to a desalination performance test via direct contact membrane distillation (DCMD), characterization studies were performed on the SSCHFM before and after grafting using different characterization techniques, such as scanning electron microscopy (SEM), atomic force microscopy (AFM), 3-points bending, water liquid entry pressure (LEPw), and water contact angle measurement. Mercury porosimetry analysis (MIP) was also used to determine the pore size distribution and porosity of the SSCHFM. The grafting process caused an increasing of the contact angle from 0° to 142.5° ± 2.0, and LEPw value of (2.6 ± 0.4 bar) was achieved. AFM images showed an increment in the surface roughness of the grafted SSCHFM from 0.305 µm to 0.375 μm, with a slight decrease in the average pore size and porosity from 0.17 µm and 17% to 0.12 µm and 14.7% respectively. After the grafting process, the performance of the membrane in DCMD was evaluated on a salt solution for 32 h at different NaCl concentrations (8,16, 24, 32 and 40) g/L, feed flow rates and feed temperatures. The results showed a decrease in the permeate flux at increasing feed concentration, but the reverse was at higher feed flow rates and feed temperatures. The surface-modified membrane recorded a water flux value of 35 kg/m2.h and 100% salt rejection. The results indicate that the hydrophobic hollow fibre ceramic membranes derived from silica sand have significant potential to be developed for membrane distillation application in water purification and reclamation.
Two main groups of samples were prepared. The first one was poly (vinyl chloride) (PVC) loaded with different concentrations of as received single walled carbon nanotubes (SWCNTs), while the second was PVC loaded with different concentrations of single walled carbon nanotubes functionalized with three-hydroxy-2-naphthoic acid (-HNA) at a concentration of 0.04wt%. The dc electrical conductivity and its temperature dependence of theses samples were investigated. Also, the tensile, rheological as well as the dynamical mechanical properties of all samples were studied. Functionalization of SWCNTs with -HNA was found to enhance the dc electrical conductivity, elastic modulus, tensile strength, complex viscosity, storage modulus and the glass transition temperature. The dc electrical conductivity had a percolation behavior with a percolation threshold concentration of 0.35 and 0.22wt% of un-functionalized and functionalized CNTs, respectively. The enhancement of the electrical and mechanical parameters with functionalized SWCNTs indicated well dispersion of CNTs due to formation of side functional groups on their sides.
Metakaolin hollow fibre membranes (MHFM) prepared by a combined phase inversion and sintering method were proposed for application in direct contact membrane distillation (DCMD). Four kinds of hydrophobic metakaolin hollow fibre membranes (h-MHFM) sintered at different temperatures (1200ºC to 1500ºC) were successfully prepared by grafting 1H,1H,2H,2H-perfluorodecyltriethoxysilane on the MHFM. Prior to the grafting process, hydrolysis with a mixture of ethanol and water with ratio 1:2 was applied for 24 hours. The effectiveness of hydrophobization on each MHFM was assessed using contact angle measurement, scanning electron microscopy (SEM) and 3-point bending. It was found that increasing sintering temperature increased the mechanical strength from 117.6 MPa to 182.3 MPa. Further increment was observed when mofification with FAS was applied. After modification, the contact angle was enhanced up to 120º. In general, membrane prepared at lower sintering temperature of 1200°C exhibited higher DCMD performance with water vapor flux of 17.5 kg/m2h due to sufficient pore size for the vapor to pass through the memrbane structure. It was suugested that this membrane is suitable for any condition of water treatment including heavy metal removal, due to its excellent properties to act in harsh condition and best DCMD performance.
Natural gas is an important and fast-growing energy resource in the world and its purification is important in order to reduce environmental hazards and to meet the required quality standards set down by notable pipeline transmission, as well as distribution companies. Therefore, membrane technology has received great attention as it is considered an attractive option for the purification of natural gas in order to remove impurities such as carbon dioxide (CO2) and hydrogen sulphide (H2S) to meet the usage and transportation requirements. It is also recognized as an appealing alternative to other natural gas purification technologies such as adsorption and cryogenic processes due to its low cost, low energy requirement, easy membrane fabrication process and less requirement for supervision. During the past few decades, membrane-based gas separation technology employing hollow fibers (HF) has emerged as a leading technology and underwent rapid growth. Moreover, hollow fiber (HF) membranes have many advantages including high specific surface area, fewer requirements for maintenance and pre-treatment. However, applications of hollow fiber membranes are sometimes restricted by problems related to their low tensile strength as they are likely to get damaged in high-pressure applications. In this context, braid reinforced hollow fiber membranes offer a solution to this problem and can enhance the mechanical strength and lifespan of hollow fiber membranes. The present review includes a discussion about different materials used to fabricate gas separation membranes such as inorganic, organic and mixed matrix membranes (MMM). This review also includes a discussion about braid reinforced hollow fiber (BRHF) membranes and their ability to be used in natural gas purification as they can tackle high feed pressure and aggressive feeds without getting damaged or broken. A BRHF membrane possesses high tensile strength as compared to a self-supported membrane and if there is good interfacial bonding between the braid and the separation layer, high tensile strength, i.e., upto 170Mpa can be achieved, and due to these factors, it is expected that BRHF membranes could give promising results when used for the purification of natural gas.
