Search

In this study, the synthesis of Fe3O4@GO@g-C3N4 ternary nanocomposite for enhanced photocatalytic degradation of phenol has been investigated. The surface modification of Fe3O4 was performed through layer-by-layer electrostatic deposition meanwhile the heterojunction structure of ternary nanocomposite was obtained through sonicated assisted hydrothermal method. The photocatalysts were characterized for their crystallinity, surface morphology, chemical functionalities, and band gap energy. The Fe3O4@GO@g-C3N4 ternary nanocomposite achieved phenol degradation of ∼97%, which was significantly higher than that of Fe3O4@GO (∼75%) and Fe3O4 (∼62%). The enhanced photoactivity was due to the efficient charge carrier separation and desired band structure. The photocatalytic performance was further enhanced with the addition of hydrogen peroxide, in which phenol degradation up to 100% was achieved in 2 h irradiation time. The findings revealed that operating parameters have significant influences on the photocatalytic activities. It was found that lower phenol concentration promoted higher activity. In this study, 0.3 g of Fe3O4@GO@g-C3N4 was found to be the optimized photocatalyst for phenol degradation. At the optimized condition, the reaction rate constant was reported as 6.96 × 10−3 min−1. The ternary photocatalyst showed excellent recyclability in three consecutive cycles, which confirmed the stability of this ternary nanocomposite for degradation applications.

Application of polymer clay nanocomposites for carbon dioxide (CO2) removal in gas separation by using mixed matrix membranes is promising due to the advancement of nanotechnology and polymer processing. In this regard, as clay is abundantly available, cheaper and has attractive physical and chemical properties, the incorporation of these silicate layers within the polymer matrix as filler is favourable. In principle, the exfoliated clay single layers create higher tortuosity effects and may improve the separation properties of the membrane. This review presents a synopsis of the polymer clay nanocomposites development and applications as well as their potential for the removal of CO2 from gas mixtures. Details of the recent works in the development of mixed matrix membranes embedded with clay for gas separation were also discussed. In addition, the problems and mechanism to evaluate the exfoliation properties were emphasized identifying the gaps and motivates for future research works utilizing clay nanoparticles as membrane filler

One of the most critical issues encountered by polymeric membranes for the gas separation process is the trade-off effect between gas permeability and selectivity. The aim of this work is to develop a simple yet effective coating technique to modify the surface properties of commonly used polysulfone (PSF) hollow fiber membranes to address the trade-off effect for CO2/CH4 and O2/N2 separation. In this study, multilayer coated PSF hollow fibers were fabricated by incorporating a graphene oxide (GO) nanosheet into the selective coating layer made of polyether block amide (Pebax). In order to prevent the penetration of Pebax coating solution into the membrane substrate, a gutter layer of polydimethylsiloxane (PDMS) was formed between the substrate and Pebax layer. The impacts of GO loadings (0.0&ndash, 1.0 wt%) on the Pebax layer properties and the membrane performances were then investigated. XPS data clearly showed the existence of GO in the membrane selective layer, and the higher the amount of GO incorporated the greater the sp2 hybridization state of carbon detected. In terms of coating layer morphology, increasing the GO amount only affected the membrane surface roughness without altering the entire coating layer thickness. Our findings indicated that the addition of 0.8 wt% GO into the Pebax coating layer could produce the best performing multilayer coated membrane, showing 56.1% and 20.9% enhancements in the CO2/CH4 and O2/N2 gas pair selectivities, respectively, in comparison to the membrane without GO incorporation. The improvement is due to the increased tortuous path in the selective layer, which created a higher resistance to the larger gas molecules (CH4 and N2) compared to the smaller gas molecules (CO2 and O2). The best performing membrane also demonstrated a lower degree of plasticization and a very stable performance over the entire 50-h operation, recording CO2/CH4 and O2/N2 gas pair selectivities of 52.57 (CO2 permeance: 28.08 GPU) and 8.05 (O2 permeance: 5.32 GPU), respectively.

With the blooming of oil and gas industries, oily saline wastewater treatment becomes a viable option to resolve the oily water disposal issue and to provide a source of water for beneficial use. Reverse osmosis (RO) has been touted as a promising technology for oily saline wastewater treatment. However, one great challenge of RO membrane is fouling phenomena, which is caused by the presence of hydrocarbon contents in the oily saline wastewater. This study focuses on the fabrication of antifouling RO membrane for accomplishing simultaneous separation of salt and oil. Thin film nanocomposite (TFN) RO membrane was formed by the layer by layer (LbL) assembly of positively charged TNS (pTNS) and negatively charged TNS (nTNS) on the surface of thin film composite (TFC) membrane. The unique features, rendered by hydrophilic TNS bilayer assembled on TFC membrane in the formation of a hydration layer to enhance the fouling resistance by high concentration oily saline water while maintaining the salt rejection, were discussed in this study. The characterization findings revealed that the surface properties of membrane were improved in terms of surface hydrophilicity, surface roughness, and polyamide(PA) cross-linking. The TFC RO membrane coated with 2-bilayer of TNS achieved &gt, 99% and &gt, 98% for oil and salt rejection, respectively. During the long-term study, the 2TNS-PA TFN membrane outperformed the pristine TFC membrane by exhibiting high permeability and much lower fouling propensity for low to high concentration of oily saline water concentration (1000 ppm, 5000 ppm and 10,000 ppm) over a 960 min operation. Meanwhile, the average permeability of uncoated TFC membrane could only be recovered by 95.7%, 89.1% and 82.9% for 1000 ppm, 5000 ppm and 10,000 ppm of the oily saline feedwater, respectively. The 2TNS-PA TFN membrane achieved almost 100% flux recovery for three cycles by hydraulic washing.

Membrane technology for industrial gas separation was begun in the 1980s and has shown significant advantages over conventional techniques such as cryogenic distillation and solvent absorption in terms of energy consumption and operational cost. The main objective of this work is to develop a simple yet effective coating technique to modify the surface properties of polysulfone (PSF) hollow fiber membranes for enhanced separation of CO2/CH4 and O2/N2. The hollow fiber membranes made of different polymer concentration (15–35 wt%) were coated with different materials (polydimethylsiloxane (PDMS) or polyether-block-amide (Pebax) or PDMS followed by Pebax) through a simple dip-coating method before subjecting to pure gases testing and instrumental characterization. Results showed that the multilayer coated membranes exhibited better performance compared to the single-layer PDMS-coated and single-layer Pebax-coated membranes. It is also found that the Pebax concentration could affect the performance of the multilayer coated membranes in which the gas permeance decreased while its selectivity decreased with increasing Pebax concentration from 1 to 3 wt.%. Further increase in Pebax concentration from 3 to 9 wt% however negatively affected selectivities as high Pebax concentration tended to cover the membrane surface with tighter polymer chain packing which led to lower free volume. Experimental results also showed that the optimized multilayer coated membrane (3 wt.% Pebax) could achieve the highest gas pair selectivity, recording 34.28 and 6.65 for CO2/CH4 and O2/N2 separation, respectively. As a comparison, the membrane coated with 1 wt% Pebax only showed selectivity of 29.47 and 6.07, respectively. The findings of this work demonstrated that multilayered coating could be performed on the outer layer of hollow fiber membranes and is not limited to the flat sheet membranes as previously reported in the literature, provided a good combination of two coating solutions were used.

Membrane technology has been applied in the treatment of natural gas since the 1980s. To become competitive with the more established technologies, and for treating low-quality gas fields, considerable efforts have been made to develop nanocomposite membranes. In this chapter, various synthesis techniques and structures of nanocomposite membranes and evaluations of their potential applications in natural gas treatment are reviewed. Furthermore, the performances of various nanocomposite membranes are elaborated in detail. The prospect of using nanocomposite membranes for natural gas treatment, in particular for CO2 removal, is discussed.

In this study, six different types of polysulfone hollow fiber membranes were fabricated from the same polymeric dope solution by manipulating several important parameters during the spinning process, aiming to find the best membrane supports for the coating layer in the gas separation process. The experimental results showed that upon the polydimethylsiloxane (PDMS) coating process, the gas pair selectivities of all six types of membranes were significantly increased with respect to carbon dioxide (CO2)/methane (CH4) and oxygen (O2)/nitrogen (N2) separation. However, the membrane support spun at higher air gap and lower dope extrusion rate was found to be the best support for PDMS coating owing to its good structural integrity that led to a good balance between gas permeance and gas pair selectivity. Further investigation showed that the use of poly(ether block amide) (Pebax) as coating material did not certainly improve both gas permeance and the selectivity of hollow fiber membranes, although Pebax was previously reported to exhibit better performance than PDMS in flat sheet membranes. One of the main reasons is the difficulty of forming a defect-free Pebax coating layer on the outer surface of hollow fibers owing to the stickiness issue among fibers upon coating. More research is still needed to optimize the Pebax coating solution and its drying process in order to achieve the full potential of such coating material for hollow fiber membranes.

Random particle distribution in mixed matrix membrane has reduced its efficiency in removing targeted pollutants. The particle that locates far from the membrane surface interacts less with the adsorbate and harnesses less light for photocatalysis. This study aims to strategically distribute particles in a mixed matrix membrane near its surface with the assistance of a magnetic field. The magnetic field strength was varied by varying the distance between the permanent magnets to the cast film at 10, 15, and 40 mm. 10 mm gap membrane (ZnFe10) possesses 1.7 wt% iron (Fe) at thin layer but moot with particle aggregation. 15 mm gap membrane (ZnFe15) with 0.8 wt% Fe posses the highest phenol degradation at 1736 mg/g with stable performance after three cycles due to balanced particle distribution. ZnFe15 exhibits the highest phenol adsorption with maximum phenol adsorption (qmDR) of 120 mg/g. The fouling studies revealed ZnFe10 has 77 wt% fouling recovery, the highest among membranes. The result indicates that the magnetic field could assist in distributing the particles and their systematic distribution near the surface, improving the overall membrane performance. Hence, particle distribution within the membrane should be taken into account when fabricating a mixed matrix membrane.

In this study, the gas separation performance of polysulfone (PSF) hollow fiber mixed matrix membranes (MMMs) incorporated with nanotubes derived from titania were investigated. Titania nanotubes (TNTs) were synthesized via facile hydrothermal method of different reaction times: 10 h and 48 h. Transmission electron microscopy (TEM), X-ray diffraction (XRD), and BET analysis were conducted to scrutinize the structural morphology of the as-synthesized TNTs. TNTs produced under prolonged reaction exhibited larger tube diameters, but have rather smaller pores. No functionalizations or modifications were made regarding the surface chemistry of the TNTs prior to blending with the spinning dope. Defect-free membranes were attained up to 0.6 wt% addition of TNT10. The measured permeances for all gases tested were profoundly increased with the addition of TNTs. PSF-TNT10 0.4 wt% MMM recorded the highest permeance enhancement (about 150%), with H2, CO2, O2 permeance of 269 GPU, 120 GPU, and 26 GPU, respectively, with O2/N2, H2/CH4, CO2/CH4, and CO2/N2 selectivity remained higher than the neat membrane. TNT48 MMM demonstrated relatively lower fluxes but higher selectivity which ascribed to its smaller internal tube diameter endowing better size-exclusion capability. The TNTs formation mechanisms were discussed to justify the evolution of gas separation performance of TNT-incorporated MMMs. In light of the findings, hydrothermal method can be regarded as a versatile technique for producing TNTs of different morphologies simply by manipulating its reaction parameters. On top of that, TNTs being a low cost material, it holds enormous potential to be widely exploited in gas separation applications.

A simple, efficient and scalable approach was developed for the fabrication of highly fouling resistance nanocomposite hollow fiber membranes with the aim of effective removal of environmentally detrimental reactive dyes. The naturally occurring halloysite nanotubes were functionalized via facile self-polymerization of m-aminophenol in mild acidic condition and employed as a hydrophilic additive. The chemical modification was confirmed by FTIR, TEM and energy dispersed X-ray (EDX) analysis. The hybrid nanocomposite membrane was prepared by dry–wet spin technique with different additive dosage. The resultant membrane was characterized in terms of contact angle, surface energy, porosity, zeta potential, elemental mapping and morphology. The permeation experiments illustrated superior water flux of 104.9 Lm−1 h−1 and 9.6% of irreversible fouling with more than 90.3% of flux recovery by the simple hydraulic cleaning. Most importantly, prepared membrane was subjected for hazardous reactive dye removal application with different experimental parameters. The hybrid membrane with 2 wt. % of additive concentration showed more than 97% and 94% for the Reactive Red 102 and Reactive Black 5 dyes respectively. This approach may also be very useful in developing high flux, fouling resistant ultrafiltration hollow fiber membranes for the other similar type applications such as hemodialysis membranes.

This study investigates the characteristics of laser annealed thin films of Al–Ga co-doped zinc oxide (ZnO:Al–Ga) nanoparticles on top of SiO2/glass. The samples are synthesized using simple sol–gel, spin coating and radio frequency magnetron sputtering methods. The studies on the structural, optical and electrical properties of the pre-annealed sample and samples annealed at different power densities are conducted using a variety of characterization techniques. The samples exhibit a hexagonal wurtzite structure. Spectroscopic and nano-imaging techniques confirm that by increasing the laser power density, the crystallinity of the samples is improved and the nanoparticle size is enhanced from ∼10 nm to ∼35 nm. Spectroellipsometry is employed to calculate the refractive index, extinction coefficient, and real and imaginary components of the dielectric constant. The resistivity exhibits a minimum value at 440 mJ cm−2. Results demonstrate that the optical band gaps of the samples are between 3.29 and 3.41 eV, which are greater than that of pure bulk ZnO (band-gap of 3.21 eV). Several vibrational modes occur as a result of the dopant combination in the ZnO lattice. A discussion on the origins of modes and their intensity changes is provided. This work suggests that a laser annealing process can be an effective tool to fabricate various thin films with enhanced crystallinity. The optical and electrical properties can also be adjusted by varying the power density.

This paper presented the application of polymeric membranes for oxygen/nitrogen (O2/N2) gas separation. Polysulfone (PSF) hollow fiber membranes were fabricated by phase inversion process using N,N-dimethylacetamide (DMAc) and tetrahydrofuran (THF) as co-solvent and ethanol as additive. The effects of bore fluid flow rate and polydimethysiloxane (PDMS) coating concentration on the separation characteristics of hollow fiber membranes were studied. Prior to gas permeation study, characterizations were performed to study the membrane morphology, its thickness and quality of PDMS coating layer on the membrane surface. It was found that the bore fluid flow rate played an important role for the O2/N2 separation as it could alter the membrane structure and dimension. The membrane fabricated with lower bore fluid flowrate exhibited better gas permeance and selectivity, owing to better structural integrity that favored the PDMS coating. The results indicated that the PSF hollow fiber membrane coated with optimum PDMS concentration could show greater O2/N2 gas permeability and selectivity relative to the PSF membrane without PDMS coating.

This chapter provides an in-depth discussion on two most advanced carbon-based nanostructured materials, graphene and carbon nanotubes (CNTs), in respect to their prospects as the future technology of desalination. The unique nanodimensions and electronic properties of these materials demonstrate the significant influence on their nanofluidic properties. Variations in the porous structure, chemistry, and surface charges are among key parameters that determine their ability for separating water molecules from hydrated salt mixtures. This has been explored through extensive molecular dynamic simulations taking into account various structures possible for nanoporous graphene and CNTs. The latest experimental works to prove the feasibility of such technology in desalination process for substituting conventional polymer-based reverse osmosis membranes are critically discussed. Novel approaches for synthesizing and fabricating polymer composite membranes thus far display their immense potential for commercialization. It would be considered another breakthrough that benefits the world by providing cost effective, sustainable solutions for acquiring clean, potable water.

Magnetic induce casting with different magnet arrangements, i.e., chain (CH-3) and circular (CR-3) formation could distribute and migrate particles differently. Zinc ferrite accumulation near the thin membrane layer has promoted elongated finger-like structure for the CH-3 and CR-3 mixed matrix membranes. CR-3 membrane excels in phenol removal at different phenol initial concentration (5, 13 and 30 ppm) and has a consistent performance within the 120 min contact time. CH-3 and CR3 membrane have higher than average phenol removal by adsorption than existing works. Boyd external diffusion and Weber and Moris model reveals that the CH-3 membrane was driven by external surface diffusion while the CR-3 membrane was driven by intraparticle diffusion. The zinc ferrite-phenol interaction favoured the pseudo-first order kinetic, while the adsorption kinetic of the CR-3 membrane is the fastest for both single and multilayer adsorbate-adsorbent interaction (Langmuir and Freundlich isotherm). Sips isotherm reveals that the CR-3 membrane possesses more adsorbent than the CH-3 membrane, translating to efficient phenol removal. CR-3 membrane has lower phenol desorption at 6.8 mg/g than CH-3 membrane with 18.71 mg/g desorbed phenol and distinctly reduced after each regeneration cycle. Magnetic induce casting can induce particle migration, and magnet arrangement influences zinc ferrite ability to adsorb phenol.

Polysulfone-based polyaniline–TiO2 containing hollow fiber membranes were prepared via a dry wet spinning method. Polyaniline (PANI) coated TiO2 nanotubes were prepared via chemical oxidative polymerisation and were incorporated into the hollow fiber membranes at different compositions. The hollow fibers were fabricated by varying the air gap distance during the spinning process. The effects of the addition of PANI coated TiO2 and the variation in the air gap distance on membrane performance, such as morphology and the permeability of the membranes, were analysed. The addition of the PANI–TiO2 nanocomposite enhanced the hydrophilicity and antifouling ability of the prepared membranes. The polysulfone hollow fiber membranes were examined for their dye rejection of Reactive Black 5 and Reactive Orange 16. The results indicated that the polysulfone hollow fibers containing 1.0 wt% of PANI–TiO2 fabricated using a 5 cm air gap can be used as a potential candidate for industrial dye rejection and showed a maximum rejection of 81.5% and 96.5% for Reactive Black 5 and Reactive Orange 16, respectively.

The limited clean water resource has urged the need to extract fresh water from non-conventional sources. Produced water (PW) is a potential source of fresh water, particularly for oil-producing countries experiencing water stress issue. The engagement of membrane-based desalination technology in the field of PW treatment brings about new possibility of water reclamation. This review highlights the state-of-the-art membrane-based technologies including both stand-alone and their hybrid system, for PW treatment and reclamation. While reverse osmosis continues as a reliable option for PW treatment, emerging technologies like forward osmosis and membrane distillation have attained increasing attentions from the desalination community. To pave a way for practical applications of membrane technologies for PW desalination, the recent advances in term of membrane properties improvement, operating condition optimization, and membrane cleaning protocols are reviewed. Finally, the challenges and future outlooks of current PW desalination technologies are also highlighted.

Mixed matrix membranes (MMMs) have received worldwide attention for natural gas purification due to their superior performance in terms of permeability and selectivity. The zeolitic imidazole framework-8 (ZIF-8) blended polysulfone (PSf) membranes have been fabricated for natural gas purification. ZIF-8 was selected due to its low cost, remarkable thermal and chemical stabilities, and tunable microporous structure. The neat PSf hollow fiber membrane and mixed matrix hollow fiber membranes incorporated with the various ZIF-8 loadings up to 1.25% were fabricated. 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 ZIF-8 nanoparticles to the MMM improved thermal stability and glass transition temperature and yielded low surface roughness. MMMs were tested using pure gases with a significant improvement of 36% in CO2 permeability and 28% in CO2/CH4 selectivity compared to the neat membrane. However, the high ZIF-8 loading reduced the separation performances. Moreover, CO2/CH4 selectivity decreased at elevated pressure (8 and 10 bar) due to CO2-induced plasticization. Previously, the incorporation of ZIF-8 particles has primarily been subjected to the fabrication of flat sheet membranes, whereas this work focused on hollow fiber membranes which are rarely investigated. Hence, the promising results obtained at low feed pressure in this study demonstrated the potential of ZIF-8 based hollow fiber membrane for natural gas purification.

Reverse osmosis (RO) is a mature desalination technology that provides an effective solution to solve global water scarcity issues. In this study, thin film nanocomposite (TFN) membrane for RO desalination was fabricated by depositing positively charged titania nanosheet (pTNS) and negatively charged titania nanosheet (nTNS) on the surface of polyamide (PA) layer through layer by layer (LbL) assembly. The pTNS was synthesized through solid-state calcination and acid ion-exchange. Though the additional step of exfoliation, single sheet nTNS with improved hydrophilicity property was obtained. The hydration layer created on the surface of TNS-PA could hinder the direct contact of salt ions with the surface of TFN membrane, hence significantly enhance the water permeability and salt rejection. The membrane surface hydrophilicity was improved and surface roughness was decreased with the increasing number of bilayers. However, the excessive pTNS/nTNS bilayer coating has imposed additional hydraulic resistance hence resulted in the reduction of water permeability. The highest water permeability of 0.8 L·m−2·h−1·bar−1 (60% improvement) was achieved with the 2 bilayers of TNS-PA TFN as compared to the pristine PA membrane. The sodium chloride (NaCl) rejection was 98.45% which was also higher than pristine membrane with rejection of 96.65%.

Asymmetric mixed matrix membranes (MMMs) incorporating Cloisite15A (C15A) clay particles were prepared using solvent evaporation and phase inversion with polyethersulfone (PES) as the membrane matrix. C15A loadings varied at 1 wt% and 5 wt%. Membrane morphological and thermal properties were evaluated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Addition of the C15A favorably altered the microscopic structure of membranes from finger-like to homogeneous sponge-like structure as the loading increased. While the amorphous nature of MMMs was retained, the thermal stability was also found to be improved with a slight decrease in glass transition temperature (T g). PES/C15A1 MMM showed the best gas transport properties, with 37% and 65% improvement in CO2 permeance and CO2/CH4 selectivity, respectively. Unlike 1 wt%, the loss in selectivity shown by 5 wt% clay loadings suggested that the interphase voids and extent of silicate layers dispersion play a significant role in the overall performance of MMMs.

This study presents an alternative approach to improve the gas separation performance of conventional asymmetric membranes. For the first time, multicomponent composite/hybrid asymmetric membrane was prepared by unifying two prominent concepts in gas separation membranes: (1) sealing or caulking asymmetric membrane imperfections by means of coating a highly permeable polymer layer, and (2) the incorporation of selective inorganic particle in polymer matrix generally known as the mixed matrix membrane. Asymmetric hollow fiber membranes (polysulfone (PSF)) was externally coated by polydimethylsiloxane (PDMS) solution containing suspended Cu3(BTC)2 metal organic framework (MOF) by dip-coating technique. FESEM–EDS mapping confirmed the increase in Cu3(BTC)2 adherence with increasing number of coating. The pure gas permeation experiment with CO2, N2 and CH4 corroborated the contribution of Cu3(BTC)2 particle to the overall composite/hybrid membrane performance. The gas permeation rates were increased with increasing number of PDMS–Cu3(BTC)2 coating applied. CO2 permeance increased from 69.7 to 109.2 × 10−6 cm3 (STP)/cm2 s cmHg after 5 consecutive coatings. In addition, the CO2/CH4 and CO2/N2 selectivities were found to be increased as well. Cu3(BTC)2 contributed to higher affinity toward CO2 due to the coordinatively unsaturated copper sites in its crystal network, which provide exceptionally high adsorptive capability for polar molecules, hence resulted in the increase of the overall selectivities and gas permeation rates across the membrane. Further development based on this study will create vast opportunities for future improvement on any commercially available gas separation membranes by implementing the method described herein.

Mixed matrix membranes (MMMs) embodying different types of organoclays, namely Cloisite ® 5, Cloisite ® 15A and Cloisite ® 30B as the disperse phase for gas separation membranes, were prepared. Polysulfone (PSF) has been used as host matrix to prepare asymmetric membranes attained by the dry–wet phase inversion casting process. FESEM analysis has revealed that defect-free asymmetric MMM morphology with no issues pertaining to non-ideal organic–inorganic interphase was fabricated. The effects of organoclay types and loadings on gas permeation properties were characterized by constant pressure and the variable volume method. From the gas permeation experiment, all nanocomposites exhibited significant reduction in the gas permeation rate even with the addition of very low clay loadings (less than 1 wt%). The results suggested that the clay particle loading dictated the extent at which the organoclays were dispersed in the polymer matrix as well as their gas discrimination ability. The information on the degree of clay dispersion, aspect ratio, and the number of clay stacks per tactoid unit was gleaned by making use of the famous phenomenological models derived by Nielsen and Cussler׳s group. PSF–C15A membranes with the loading of 0.05 wt% were found to be comprised of exfoliated clay nanoplatelet (confirmed by XRD and TEM analysis) with calculated aspect ratio of more than 500 giving rise to striking selectivity (CO 2 /CH 4 ideal selectivity=52.67 for PSF–C15A 0.05 ) well above the recognized intrinsic selectivity for PSF membrane.

Asymmetric MMMs were fabricated containing various amount of organically modified clay particle (Cloisite® 15A) with the main intention to investigate the gas permeation behavior of the resultant material combination. The fabricated MMMs were characterized by X-ray diffraction (XRD), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), field emission scanning electron microscopy (FESEM) and pure gas permeation testing. XRD analysis suggested that clay layers crystalline structure was slightly changed upon blending but only limited polymer chain intercalation occurred thus resulted in phase separated clay–polymer composite. The gas permeation properties were evaluated by pure gases: nitrogen, oxygen, methane, and carbon dioxide. The gas permeation rate was observed to be increasing with increasing clay content while the selectivity remained at par to that of unfilled PSF before it declined at 2 wt.% C15A loading due to filler agglomeration as confirmed by FESEM. The best results were obtained at 1 wt.% C15A loading where more than 270% enhancement in O2 and CO2 permeance were observed, with insignificant change in O2/N2 and CO2/CH4 selectivity compared to that of neat PSF.

Biofouling is a persistent and unmet challenge in reverse osmosis (RO) technology. The attachment of microorganisms on the membrane surface has severely deteriorated the performance of RO membranes hence significantly affected the overall productivity and energy consumption of the system. Different strategies have been established to mitigate the thorny issue in order to minimize the adverse impacts of biofouling. This contribution provides a comprehensive review on the contemporary strategies that are focused on RO membrane design and modification to address the biofouling issues. The strategies for the development of anti-biofouling RO membrane in terms of material characteristics and selections as well as the techniques established to render anti-biofouling properties are extensively discussed. The performance of RO membranes through approaches including coating, layer by layer, grafting immobilization and surface patterning are reviewed. Finally, this review is wrapped up with the technological issues and challenges as well as the future perspective of these strategies.

Measuring the growth parameters of Ge quantum dots (QDs) embedded in SiO2/Si hetero-structure is prerequisite for developing the optoelectronic devices such as photovoltaics and sensors. Their optical properties can be tuned by tailoring the growth morphology and structures, where the growth parameters optimizations still need to be explored. We determine the effect of annealing temperature on surface morphology, structures and optical properties of Ge/SiO2/Si hetero-structure. Samples are grown via rf magnetron sputtering and subsequent characterizations are made using imaging and spectroscopic techniques.

Defect-free asymmetric Polysulfone (PSF)-Cloisite 15A ® nanocomposite membrane was fabricated with the intention to investigate the gas permeation behavior of the resulting material combination. Various weights of Cloisite 15A ® organoclay were added into PSF matrices by solution intercalation method assisted by sonication dispersion. The gas permeation properties of the PSF-Cloisite 15A ® nanocomposite membranes were evaluated by pure gases: nitrogen, methane, and carbon dioxide. The distribution of Cloisite 15A ® particles in PSF matrices was analyzed by SEM. The gas flux of the PSF-Cloisite 15A ® nanocomposite membranes declined as the Cloisite 15A ® weight loading increased. The CO 2 /CH 4 and CO 2 /N 2 pure gas selectivity of PSF nanocomposite with 0.5 wt. % of Cloisite 15A ® loading exceeded that of neat PSF membrane. The decrease in flux followed by the increase in pure gas selectivity was related to the way in which the clay layers were dispersed in the PSF matrices. Considerable improvement in CO 2 selectivity was attainable even by incorporating low amount of such layered structure nanoparticle which can be attractive in producing robust materials for CO 2 -removal membranes from CO 2 -containing gas streams such as post-combustion and natural gas streams.