Amine modified mixed matrix membranes (A-Ms) have been developed with improved anti-plasticization behavior at high pressure for natural gas purification. The neat PSf hollow fiber membrane and amine modified zeolitic imidazole framework-8 (A-ZIF-8) blended polysulfone (PSf) membranes have been fabricated at different A-ZIF-8 loadings for natural gas purification. The prepared membranes were evaluated using field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), and gas separation performance. The low loading of A-ZIF-8 nanoparticles improved thermal stability, glass transition temperature and surface roughness. A-Ms fabricated with 0.25 wt% A-ZIF-8 were tested using pure gases with a significant improvement of 50, 72 and 69% in CO2/CH4 selectivity 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 6, 8 and 10 bar (g) feed pressure, respectively. However, the further increase in the A-ZIF-8 loading has reduced the separation performances. Therefore, this excellent gas separation performance shows improved anti-plasticization behavior at high feed pressure which is rarely investigated. Hence, the promising results obtained at high feed pressure in this study demonstrated the potential of A-ZIF-8 based hollow fiber membrane for natural gas purification at high pressure.
Nonylphenol (NP) is one of refractory degradation intermediates of nonylphenol ethoxylates (NPEO) surfactant and among the most toxic and prevalent endocrine disrupting compounds (EDCs) found in the environment. This paper reports an effort in removing nonylphenol in water using novel photocatalytic dual layer hollow fibre membrane, where the outer layer comprised of polyvinylidene fluoride (PVDF)/titanium dioxide (TiO2) while the inner layer was 100% PVDF. Single layer hollow fibre membrane which consists of PVDF/TiO2 was also fabricated as the control sample. The presence of TiO2 on the outer surface of both dual and single layer hollow fibres was confirmed by scanning electron microscopy (SEM), energy dispersion of X-ray (EDAX) and contact angles analysis. The removal of 85% in NP concentration was achieved for dual layer hollow fibre after 4h UVA irradiation in submerged membrane photoreactor, compared to 70% for the single layer one. The kinetic rate of dual layer membranes was calculated to be 0.0092min−1 against 0.0062min−1 for the single layer counterpart. In general, dual layer hollow fibre membranes exhibited superior photocatalytic performance in comparison to single layer hollow fibre membranes due to the better dispersion of TiO2 on the outer membrane surface.
This study aims to provide a close insight into the possibilities and constraints associated with the development of ZnO structures on polyvinylidene fluoride (PVDF) hollow fiber membranes using the hydrothermal method to enhance membrane surface roughness for improved fouling resistance in membrane distillation (MD). Due to the flexible nature of polymeric hollow fiber membranes, there is a considerable risk of the ZnO structure detaching from the membrane surface when the membrane is bent. To address this issue, the hydrothermal duration was varied between 4 and 16 h to optimize the ZnO structure for high integrity, followed by fluorination. The results reveal that the membrane treated with hydrothermal for 8 h exhibits stable coating integrity, imparting the membrane with the highest contact angles with various liquids. This membrane demonstrates a flux of 4.0 kg/m2h and excellent salt rejection (>99.9 %) in direct contact MD (DCMD) when treating a 35 g/L saline solution. Additionally, the membrane exhibits outstanding antifouling performance with minimal flux reduction over 24 h when treating a saline solution containing humic acid. However, the upscaling of the hydrothermal approach may pose challenges due to the difficulty in maintaining the consistency of ZnO structure formation.
No abstract is provided for this article.
The study of the kenaf core fiber – polymer composites was done by preparing a kenaf/polymer composite using polypropylene (PP) polymer matrix and Scona TPPP 9012 GA as coupling agent with Nigerian grown Kenaf natural fiber through hot pressing. The objective was to characterize the stability and bond strength of the polymer/fiber interface through morphological analysis by using Scanning Electron Microscopy (SEM) as well as the characterization of thermal and mechanical properties of the composite. The result obtained shows an increment in tensile strength as a percentage of kenaf fiber increased to 30%, this trend continuous surprisingly, even at 50% kenaf fiber loading, which goes against the result obtained in previous literature. Thus, signifying the positive influence of Scona TPPP 9012 GA coupling agent. However, further analysis indicated that 40% kenaf fiber loading has a better chance to be considered suitable for use in the automotive structure.
Membrane separation is the most promising water treatment technology that combines high separation efficiency, modest operation, concise of space, low footprints, and low operating cost. However, the current membrane technology has limitations in permeability and solute rejection which are highly influenced by membrane material and operating conditions. Recent studies show that the graphene oxide (GO) incorporation on membrane promotes the permeation and metal ions rejection rates efficiently. Many efforts have been made to improve the waste removal performance of GO using a variety of techniques. This chapter mainly focuses on the applications of GO-based nanofiltration membranes (GO-NFMs) for heavy metals (HMs) removal from polluted water. It also covers membrane types, fabrication methods, unique properties of GO, and characterization techniques. Parameters required for best-performing GO-NFMS along with rejection mechanisms and factors affecting the performance of membranes for the removal of HM ions from wastewater have also been discussed. A good comparison of GO-NFMs with conventional membranes and efficiency of GO-modified polymeric membranes have also reviewed in the chapter. Perspectives, recommendations, and challenges for future development of GO-NFMs technologies for metal ions removal are given as complement at the end of the chapter.
Recent efforts to realize appropriate hollow fiber membranes (HFMs) for treatment of complex wastewater such as oilfield produced water (PW) have resulted in designing unique surfaces like the omniphobic, for use in membrane distillation (MD) to combat pore wetting and fouling/scaling. However, HFMs, despite their unique advantages, suffer from mechanical inadequacies. The use of polyethylene terephthalate (PET) braid support to strengthen HFMs is gaining attraction for filtration membranes, although their application in MD is scarce. Herein, we report a pioneering omniphobic PET braid-reinforced HFMs (OBRMs) for application in direct contact membrane distillation (DCMD) of PW. The effects of feed type, feed flow rate, feed temperature, and prolonged testing on performance OBRMs are reported. From the obtained findings, a thin polymer (PVDF) layer (∼68 μm) with a single-layer finger-like structure allowed for good vapor flux (up to 15 kg/m2h) while omniphobic skin layer was instrumental in keeping oils and surfactants at bay. Complex PW feed is shown to have more adverse effect on strength of OBRMs than saltwater. Increased temperature negatively affects tensile strength while a turbulent flow regime keeps foulants at bay and mitigates fouling-assisted deterioration. Prolonged testing for nine DCMD cycles (72 h) of treating PW recorded flux recovery up to 85 %, with salt rejection remaining above 99.9 %, a total organic carbon (TOC) rejection up to 98 % and a decline in tensile strength of used membranes by 6.5 %.
No abstract is provided for this article.
The incorporation of lithium oxide (Li<sub>2</sub>O) as a liquid phase sintering additive has specific advantages for electrolyte membrane fabrication.
Solid oxide fuel cells (SOFCs) have been considered as a promising electricity-generation technology because of the relatively high efficiency in the conversion of chemical energy to electrical power. The cathode performance of solid oxide fuel cells (SOFC) depends substantially on its surface area, porosity and microstructure, and therefore the processing method used is very important in determining cathode performance. By optimizing the structural characteristic of the layer, the cathode performance during fuel cell performance can be fully maximized. Polyether ether ketone (PEEK) pore former was introduced in the processing method of cathode layer. The cathode layer was brush painted and sintered at 1200°C for 5 hours. TGA analysis is used to specify the sintering curve for the cathode layer. In addition, three point bending test is used to investigate the change in bending force with the addition of pore former. Characterization via FESEM allows inspection over the induced pore geometry and distribution along the layer. The study can produce a comprehensive structural analysis on the pore former addition in the precursor solution of the cathode layer for SOFC application.
Mono phase CuO thin films through DC sputtering at various oxygen pressure (10, 20, 30, 40sccm) was deposited on glass substrate. The structural analyses of the DC sputtered thin films were performed through X-ray diffraction (XRD) technique. The atomic force microscope (AFM) exposed the variation in surface roughness with the change in the deposited Oxygen pressure of CuO thin films. The band gap at various oxygen pressures was also estimated. The dielectric properties in term of real/imaginary dielectric constants and dielectric loss have also been investigated. The surface chemical composition of deposited CuO thin films has been examined through X-ray photoelectron spectroscopy (XPS). The Cu2p spectra indicated the presence of Cu2+ covalent bond with d9 configuration at ground state. The O1s spectra proved the increment in the chemisorbed oxygen (Oi) with the enchantment of deposition oxygen pressure. The nonlinear optical constant such as nonlinear refractive index, linear optical susceptibility and third order nonlinear susceptibility were also calculated through very simple inexpensive method. The advantage of this work is to calculate the linear and nonlinear optical investigations through spectroscopic approach rather than expensive experimental Z- scan method.
