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The sustainability of global clean and safe water supply is one of the grand challenges facing the world. Membrane technology based on polymeric membranes is one of the most important and widely recognized technologies for desalination and wastewater treatment. While polymeric membranes are known to be plagued with some bottlenecks, the technical progress and the accompanying knowledge in inorganic membrane development have grown inexorably to solve some of the underlying issues. Aside from the conventionally used ceramic membranes which based on metal oxides, nanostructures such as zeolites, metal organic frameworks and carbon based materials have sparked enormous interest in the preparation of inorganic membranes owing to their tunable nanoscaled structural properties that can render excellent rejection and/or ultrafast water transport. This review provides insights into the physico-chemical properties and fabrication approaches of different classes of inorganic membranes. The transport mechanisms that are associated to their unique structural features are also discussed. Furthermore, the performance evaluation of these inorganic membranes in a wide spectrum of desalination and wastewater treatment applications are also elaborated. Finally, the challenges in the development of inorganic membrane for practical commercial application are identified and the future perspectives are presented. [ABSTRACT FROM AUTHOR]

Multidisciplinary, innovative and high values development of high performance, cost-effective and environmentally acceptable separation systems is highly desired to tackle the sustainability challenges that facing current desalination technology. Owing to their versatility and immense potentials to evolve scientific and technical innovations, nanotechnology is probably one of the most prominent strategies that has gained growing scientific and public recognition to provide solutions that can extend the limits of sustainability in membrane desalination technology. This short review provides a brief insight into the roles and prospective of nanotechnology, particularly the nano-enabled membrane technology, to serve as a key element to render feasible solutions for sustainable development in membrane desalination technology. The contribution also highlights the strategies of transforming risk and challenges of this cutting edge technology into competitive advantage in order to timely and efficiently drive values in enhancing the desalination performance, profits and sustainability. The applications of nanomaterials and nanocomposite in membrane desalination are anticipated to foster untapped initiatives and innovation in fundamental science, engineering and technology to spearhead the new wave of leading edge sustainable membrane desalination technology. [ABSTRACT FROM AUTHOR]

Membrane (bio)fouling is a major obstacle to many separation and purification processes. Due to the inherent physicochemical properties of some thin film composite membrane surfaces such as polyamide, these are prone to (bio)fouling. Hence, this review highlights recent advances in the design and development of highly resistant thin film composite membrane through surface modification by either coating or grafting with antifouling polymers and/or antimicrobial polymers/biocidal inorganic nanoparticles. [ABSTRACT FROM AUTHOR]

The surface hydrophobicity of membrane is a key factor in contactor applications where the penetration of liquid into membrane pores has negative effect on the contactor performance. Therefore, different methods have been proposed for surface modification. Blending hydrophobic polymers such as surface modifying macromolecules (SMM) has been investigated in our earlier researches. In this study, the effect of polyvinylidene fluoride (PVDF) blending on the surface and bulk morphology of polyetherimide (PEI) hollow fiber membrane and its performance in membrane gas absorption process was studied. It was found that the pore size increased from 112 nm to 210 nm from the neat PEI membrane to the PEI membrane spun from the solution blended with 0.25 wt% PVDF. At the same time, the contact angle increased from 78.3 and 84.3. Furthermore, the absorption flux of PVDF blended membrane enhanced by 13% compared to the neat PEI membrane. [ABSTRACT FROM AUTHOR]

The main focus of this review article is the introduction of relevant parameters in spray coating processes to provide better understanding on controlling the morphology of spray coated thin films for producing high performance polymer solar cells (PSC). Three main parameters have been identified as major influences on the spray coating processes. These are nozzle to substrate distance, solvent and mixed solvents effects, and substrate temperature and annealing treatment. Such spray coating techniques show great potential for large scale production, since these methods have no limitation in substrate size and low utilization of polymers which is promising to substitute the conventional spin coating methods. Currently available printing and coating methods are also briefly discussed in this review. [ABSTRACT FROM AUTHOR]

Asymmetric PEI hollow fiber mixed matrix membranes (MMMs) with improved structure and wetting resistance were fabricated via wet phase inversion method. The effects of incorporating hydrophobic MMT into polymer matrix in different loadings on the membrane properties were investigated. The membranes were characterized in terms of scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX), gas permeation test, hydrophobicity, wetting resistance and mechanical stability. All membranes possessed finger-like structures differing in skin layer thickness which increased with clay loading. The results revealed that the MMMs have significantly smaller pore size, higher porosity, hydrophobicity, LEPw and mechanical stability than plain PEI membrane. The membranes were further characterized by CO 2 absorption test via contactor system using distilled water as absorbent and pure CO 2 as solute gas. The results showed that the CO 2 absorption performance increased with addition of MMT nano-clay. The membrane containing 1 wt% MMT recorded the highest absorption flux of 2.35 × 10 −3 mol m −2 s −1 at the liquid velocity of 3 m s −1 , almost 135% higher than the flux of plain membrane at the same velocity. Comparatively, the flux of MMM was superior to several in-house made and commercial membranes. [ABSTRACT FROM AUTHOR]

In this study, flat sheet asymmetric MMMs were prepared from polyethersulfone (PES) containing 1 (PES/C15A1) and 5 wt% (PES/C15A5) loading of Cloisite15A® via phase inversion to investigate the effect of dispersion of silicate layers on the properties and performance of the MMMs for CO 2 /CH 4 separation. The MMMs were characterized by means of WAXD, TEM, tensile test and pure gas permeation measurement. Partial intercalated and exfoliated silicate layers for MMM with 1 wt% loading contributed to the enhancement of the membrane morphological and mechanical properties. The increase tortuosity in PES/C15A1 reduced the CH 4 permeance with a significant enhancement for the CO 2 /CH 4 selectivity from 22.57 to 46.89. In addition, high degree of intercalation and exfoliation of silicate layers was also corroborated by particle size measurement (PSM), particle density measurement (PDM) and free-path spacing measurement (FPSM) with the increase in aspect ratio, dispersed single silicate layers, density and formation of several tactoid classes for PES/C15A1. The properties and performance of the MMMs, determined by qualitative and quantitative measurements for PES/C15A1 was higher compared to PES/C15A5; therefore, the extent of the silicate layers dispersion has a significant role in the fabrication of asymmetric MMMs. [ABSTRACT FROM AUTHOR]

This study focuses on the design and performance of a hybrid system consisting of a photocatalytic reactor and a membrane permeation cell. Initially, an ultraviolet lamp was installed in the photocatalytic reactor to decompose the organic pollutants in the presence of 200 ppm titanium-dioxide (TiO 2 ). Individual hydrocarbon pollutants were identified by gas chromatography–mass spectrometry (GC–MS) analysis of wastewater samples. Polyvinylidene fluoride (PVDF)/multi-walled carbon nanotube (MWCNT) nanocomposite membranes were fabricated to enhance the rejection, flux and fouling resistance for full filtration of pollutants from photocatalytic reactor such as decomposed refinery wastewater and TiO 2 photocatalyst. The nanocomposite membranes were characterized by Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The TiO 2 cross-over during permeation was detected by using an atomic adsorption spectrometer, which proved that TiO 2 rejection was more than 99% for oxidized MWCNT nanocomposite membranes. Furthermore, GC–MS analysis was concluded over 90% decomposition which occurred by photocatalytic reaction and practically all pollutants were removed by ultrafiltration permeation cell. The nanocomposite membrane with 1.0 wt.% of oxidized MWCNTs incorporated in PVDF matrix was found to be the best nanocomposite membrane among all of the fabricated membranes for the filtration purposes, due to the over 99% rejection and excellent anti-fouling property. [ABSTRACT FROM AUTHOR]

Porous polyetherimide (PEI) and polyethersulfone (PES) hollow fiber membranes were spun under the same spinning conditions and the fabricated membranes were characterized using various analytical methods. The membranes were then subjected to gas–liquid contactor experiments. While the PEI casing solution was thermodynamically less stable, the PES casting solution was less viscous which resulted in a more porous membrane structure. The mean pore size and effective surface porosity obtained by the gas permeation test showed superior properties of the PES membrane. Both PEI and PES membranes had sufficiently high LEPw values even though both polymers were known to be relatively hydrophilic, most likely due to their small pore sizes. The absorption flux of the PES membrane was 4.4×10 −3 mol m −2 s −1 at the liquid flow velocity V liquid of 1.8 m s −1 , which was 267% higher than that of the PEI membrane (1.2×10 −3 mol m −2 s −1 ) due to the larger pore size and smaller tortuosity of the PES membrane. [ABSTRACT FROM AUTHOR]

Polyvinylideneflouride (PVDF) hollow fiber mixed matrix membranes (MMMs) were fabricated through wet phase inversion method using general MMT and Cloisite 15A as inorganic fillers. The effect of clay filler loadings (1, 3 and 5 wt% of polymer), their particle size and hydrophobicity on the membrane morphology, structure and performance in gas–liquid contacting process were investigated. The fabricated MMMs were characterized by scanning electron microscopic (SEM), gas permeation test, hydrophobicity, wetting resistance and CO 2 absorption test. As expected, MMMs showed asymmetrical structure, differing in finger-like portion, porosity and pore size. The fabricated MMMs with higher finger-like area and surface porosity showed higher permeance than plain membrane. Furthermore, the wetting resistance in terms of surface hydrophobicity and liquid entry pressure of water increased with loading. From the point of view of physical CO 2 absorption, the membranes incorporated with small particle size filler (general MMT-filled PVDF membranes) exhibited higher absorption fluxes than those embedded with large particle size fillers. The highest absorption flux for membrane containing 1 wt% general MMT is 1.0 × 10 −3 mol m −2 s −1 at the flow rate of 3.1 m s −1 . That flux was approximately 54% and 82% higher than the flux of MMMs with embedded Cloisite 15A of the same loading and plain PVDF membrane, respectively. The obtained flux of synthesized membrane was superior compared to several in-house made and commercial membranes. [ABSTRACT FROM AUTHOR]

Advanced science and technology based on graphene-based nanomaterials is experiencing a rapid rate of change in the performance capabilities to substitute or serve as alternative approaches for the existing technologies. In the context of water treatment, more particularly in field of desalination, significant numbers of breakthroughs have been achieved to drive accelerated change for ceaseless capability improvements. In this contribution, the unique features of graphene-based nanomaterials that have generated tremendous interest among the material researchers are described along with their potential applications in desalination. Another aim of this paper is to provide comprehensive scientific progress of these nanomaterials in order to explore the challenges and opportunities of graphene-based nanomaterials in advancing current desalination technology. Finally, a future prospective on how this rapidly emerging field may evolve from short to medium and long term is highlighted and the outlooks regarding the technological challenges, economical implication and toxicological impact of graphene-based nanomaterials on the environment are briefly discussed. As this novel carbon nanostructured material will certainly offer exciting and tunable features for desalination technology, it is anticipated that by grabbing the approaching opportunities and tackling the encountered challenges, these astonishing materials could very well make clean water more accessible around the globe. [ABSTRACT FROM AUTHOR]

A coherent review on the advanced proton exchange membranes (PEMs) for direct methanol fuel cell (DMFC) application and the future direction in the development of a high performance polymeric membrane for DMFC were discussed in this paper. PEMs have a profound influence on performance of DMFC. The PEMs are categorized into five groups which are partially fluorinated, perfluorinated ionomers, acid–base complexes, non-fluorinated ionomers, hydro carbon and aromatic polymers. Many researchers have investigated the functionalization methods on the PEMs to solve methanol crossover problem while obtaining low electronic conductivity, high proton conductivity, low electro osmotic drag coefficient, high mechanical properties and good chemical and thermal stability. Including in this review, fabrication of PEM using electrospinning process coupled with the promising functionalized polymeric materials which were known to be the most important initiatives at present in order to further expand the full potential of DMFC performance. [ABSTRACT FROM AUTHOR]

Randomized particle distribution in a mixed matrix membrane would reduce the effectiveness of particle immobilized in its matrix. This study aims to distribute the particle near the membrane surface with magnetic field assistance. Specifically, investigating the influence of varied magnetic patterns (rod, chain, and circular) on zinc ferrite distribution in the membrane on the phenol adsorption with the standing time was fixed at 30 s with 12 wt% zinc ferrite. The findings revealed that the magnetic induce membrane possesses the highest phenol adsorption, especially by membrane fabricated by magnets in a circular pattern (MB). MB membrane displayed phenol adsorption capacity of 415 mg/g with water permeation of 30.4 L/m2.h. The high phenol adsorption was contributed to high zinc ferrite particle migrated towards the membrane surface, and EDX analysis revealed 1.23 wt% Fe element in its thin layer region. These findings indicate that the magnets arranged in a circular pattern can effectively migrate and distribute the zinc ferrite across the membrane. Hence, a suitable magnetic pattern was vital when applying magnetic induce casting. [Display omitted] • The magnet in magnetic induced casting was arranged to circular, chain, and rod. • Circular pattern (MB) has the highest phenol adsorption capacity at 415 mg/g. • MB and MC (chain) membrane driven by external diffusion with film thickness Δr o of 5.22 and 16.94 nm. [ABSTRACT FROM AUTHOR]

Casein is an important protein in the raw milk and many approaches have been established to separate casein to make cheese. This study mainly deals with the analysis of casein protein (19 kDa, pI 4.6) transport characteristics through ultrafiltration (UF) membranes. Polysulfone (PS) based polymer membranes are used and modified with polyethylene imine (PEI), polydiallyl dimethyl ammonium chloride (PDDA) and polyacrylic acid (PAA). The fabricated membranes are characterized by contact angle and Fourier transforms infrared (FTIR) spectroscopy. The UF process was conducted with a dead-end filtration unit and the volumetric flux and transmission values are recorded and that varies with pressure and pH. The experimental results are explained using the concentration polarization and irreversible thermodynamics model. The characteristics of the transport of casein are determined from the values of the parameters such as the solute concentration near the surface of the membrane [Cm], the solute permeability [Pm], mass transfer coefficient [k], and the reflection coefficient [σ]. From the results, it is concluded that the casein transport through the UF membrane was controlled by convection with decrease in casein rejection. Although, this model predicts the transmission behavior as a function of flux and supports the experimental results for both membranes. [ABSTRACT FROM AUTHOR]

Abstract: A novel composite membrane was prepared using chitosan (CH) as the active layer supported on a Poly(1,4-phenylene ether ether sulfone) (PPEES) membrane. The chitosan layer was ionically cross linked with sodium tripolyphosphate (TPP). The composite nature of PPEES/CH membranes was confirmed by Scanning Electron Microscopy (SEM). Infrared (IR) spectroscopy results and SEM–EDX analysis confirmed the crosslinking of chitosan surface with TPP. The membranes exhibited higher crosslinking density in acidic media than in basic media. The changes in the hydrophobic nature of PPEES membrane surface due to deposition of chitosan active layer followed by crosslinking were studied by their contact angle measurement, water flux and water uptake studies. The membranes showed rejection up to 55% and 21% towards MgSO4 and NaCl respectively at pH=5 and a flux recovery ratio of 73%. [Copyright &y& Elsevier]

Highlights: [•] Zeolite 4A loaded Pebax-1657 mixed matrix membranes were synthesized. [•] Performance of membranes was studied with pure CO2, CH4, O2 and N2 gases. [•] Pebax/4A membranes showed better gas permeation properties to those of Pebax-1657. [•] Increasing the zeolite loading enhanced the selectivity CO2/CH4, CO2/N2 and O2/N2. [ABSTRACT FROM AUTHOR]

Highlights: [•] Toluene prevent coffee ring effects. [•] Increase crystallinity. [•] Increase absorption. [Copyright &y& Elsevier]

Highlights: [•] Asymmetric mixed matrix membranes were fabricated. [•] Organoclay particles known as Cloisite® 15A were incorporated in PSF matrix. [•] Permeability of CO2, O2, N2, and CH4 increased with increasing filler loading. [•] O2/N2 and CO2/CH4 selectivity was maintained up to 1wt.% C15A loading. [ABSTRACT FROM AUTHOR]

Highlights: [•] Effects of tapioca starch and CGTase concentrations on the yield of CDs were studied. [•] Production of CDs in an EMR. [•] The weak adsorption (ra1 ) was the major fouling mechanism. [ABSTRACT FROM AUTHOR]

Abstract: The objective of this study is to propose a novel approach for predicting the structural parameters of integrally skinned porous membranes using gas permeation data. It is intended to overcome the limitation of the conventional gas permeation testing (GPT) method, since the latter method seems to suffer from several conceptual drawbacks. In particular, a comparison is made between the theoretical calculation and the experimental data to show the superiority of the newly proposed model. The new model is a modification of Wakao et al.'s model, in which, unlike the conventional GPT method, the contribution of the slip flow is considered. Although Wakao et al.'s model was found superior to the conventional GPT method, the model fitting to the experimental data was not completely satisfactory. It was likely that the slip flow, although its effect cannot be neglected, is not fully developed. Therefore, a factor ψ is introduced to show the extent of the contribution of the slip flow mechanism to the total gas permeation rate. As a result, the new method can overcome the shortcomings of the conventional GPT method by manifesting the following advantages: (i) it can cover the entire range of J versus P diagram, (ii) it can specify the contribution of the individual mechanisms involved in the total gas permeation and (iii) unlike the conventional GPT method, it is not limited by any constraints or conditions of data acquisition. In summary, the model can predict pore size and effective porosity, and also simulate the experimental J versus P trends with sufficient accuracy (within ~2% over the pressure range studied) for all types of membranes, i.e. NF, UF, MF, MD and membrane contactors. In view of this fact, the proposed model is simpler to apply than Rangarajan et al.'s model and more accurate than the conventional GPT method. [Copyright &y& Elsevier]

Highlights: [•] SPEEK/CC/TAP was successfully prepared. [•] The incorporation of TAP improve dispersion of CC in SPEEK. [•] The proton conductivity and methanol permeability measured at moderate temperature. [•] Incorporation of CC and TAP improved the performance DMFC at elevated temperatures. [Copyright &y& Elsevier]

Highlights: [•] Different amount of SMM were used to improve the surface hydrophobicity of PVDF HFM. [•] Average pore size and contact angle increased by increasing SMM concentration. [•] The fabricated PVDF HFMs were used in contactor application for CO2 absorption. [•] The CO2 flux of the hollow fiber increased by increasing SMM concentration. [•] The membrane mass transfer resistance decreased by enhancement of SMM concentration. [Copyright &y& Elsevier]

This article aims to provide an insight into the use of carbon nanotubes to enhance the performance of available sea-water and brackish water desalination systems in a holistic manner. It looks at current hurdles and future challenges that relate to the use of this material. [ABSTRACT FROM AUTHOR]

Highlights: [•] The effect of different fiber packing density was studied in membrane contactor. [•] Increasing packing density produces decreasing trend of CO2 absorption flux. [•] Overall mass transfer resistance reduced with increasing packing density. [Copyright &y& Elsevier]

Highlights: [•] Beta-cyclodextrin was used to functionalize raw MWCNTs. [•] The TEM results showed beta-cyclodextrin can attach to the outer surface of the MWCNTs. [•] After functionalization, shortened and less agglomerated MWCNTs were achieved. [•] TGA revealed that the functionalized MWCNTs are thermally less stable than raw MWCNTs. [•] Functionalized MWCNTs increased selectivity of the mixed matrix membranes considerably. [Copyright &y& Elsevier]

Highlights: [•] A critical review on the conventional gas permeation testing (GPT). [•] Determining shortcomings of the conventional GPT. [•] Applying the conventional GPT leads to erroneous predictions. [Copyright &y& Elsevier]

Abstract: Polysulfone (PSf)/poly (isobutylene-alt-maleic anhydride) (PIAM) nanofiltration membranes were modified by changing the coagulation bath with various concentrations of glutaraldehyde cross-linked Chitosan solutions. Further the membranes were treated with 0.1N NaOH solution in order to achieve the hydrolysis of PIAM. The morphological changes of the membranes were determined using scanning electron microscope. The blending of PSf/PIAM membrane, the incorporation of Chitosan (CS) molecules in membrane matrix and the hydrolysis of PIAM in the membrane upon alkali treatment were studied by Attenuated Total Reflectance Infra Red (ATR-IR) spectroscopy. The hydrophilicity of modified membranes was measured using the contact angle analyzer. The pressure and time dependent pure water flux of modified PSf/PIAM/CS membranes were measured and compared with PSf/PIAM membranes (after alkali treatment). The antifouling property of membranes was determined using Bovine Serum Albumin (BSA) protein rejection studies. The modified membranes showed improved hydrophilicity and reduced pore size. The order of rejection of membranes for various electrolytes was Na2SO4 >MgSO4 >NaCl at minimum pressure of 0.2MPa TMP. The antifouling property of modified membranes increased with an increase in the composition of Chitosan in coagulation bath and membrane M-0.8 showed a maximum fouling resistance ratio of 74%. [Copyright &y& Elsevier]

Abstract: Carbon dioxide (CO2) stripping from water was conducted through the porous asymmetric polysulfone (PSf) hollow fiber membrane contactor. The effect of the liquid and gas flow rates on the stripping performance, the liquid phase CO2 concentration and the CO2 stripping efficiency of the membrane module and the effect of liquid phase temperature on CO2 stripping flux were studied. The experimental results showed that the stripping gas velocity had a minor effect on the CO2 desorption flux while the increase in the liquid velocity could enhance CO2 desorption flux in the gas stripping membrane contactor. By increasing liquid flow rate to 200ml/min, the maximum CO2 stripping efficiency of almost 66% was achieved. Enhancement of liquid flow rate from 50 to 200ml/min increased the CO2 flux around 482%. It was found that the CO2 stripping flux was significantly affected by the liquid phase temperature. By increasing liquid temperature from 80 to 90°C, the CO2 stripping flux increased from 1.3×10−4 to 4.9×10−4 molm−2 s−1 at liquid velocity of 200mlmin−1. Hence, the higher stripping efficiency can be achieved by applying the higher liquid flow rate in the membrane contactor module. As well, the liquid phase temperature is a key parameter that needs to be controlled. [Copyright &y& Elsevier]

Abstract: A series of polyetherimide (PEI) hollow fiber membranes with various polymer concentrations (13–16wt.%) for CO2 stripping process in membrane contactor application was fabricated via wet phase inversion method. The PEI membranes were characterized in terms of liquid entry pressure, contact angle, gas permeation and morphology analysis. CO2 stripping performance was investigated via membrane contactor system in a stainless steel module with aqueous diethanolamine as liquid absorbent. The hollow fiber membranes showed decreasing patterns in gas permeation, contact angle, mean pore size and effective surface porosity with increasing polymer concentration. On the contrary, wetting pressure of PEI membranes has enhanced significantly with polymer concentration. Various polymer concentrations have different effects on the CO2 stripping flux in which membrane with 14wt.% polymer concentration showed the highest stripping flux of 2.7×10−2 mol/m2 s. From the performance comparison with other commercial membrane, it is anticipated that the PEI membrane has a good prospect in CO2 stripping via membrane contactor. [Copyright &y& Elsevier]

Abstract: The behavior of sulfonated poly (ether ether ketone) (SPEEK) with different degrees of sulfonation (DS) (60–76%) blended with charged surface modifying macromolecule (cSMM) at different operating temperatures as an electrolyte membrane for direct methanol fuel cell (DMFC) application has been studied. A good DMFC electrolyte membrane should possess high proton conductivity and low methanol permeability. In this work, the fabricated SPEEK/cSMM membranes were compared with pure SPEEK and commercial Nafion 112 membranes in terms of water uptake, proton conductivity, and methanol permeability at temperature range of room to 80°C. The water uptake of SPEEK/cSMM membranes increased with the temperature and it was higher than that of SPEEK and Nafion 112 membranes; however newly fabricated membranes with 68% and 76% DS were dissolved at high temperatures although showed the same trend at lower temperatures. In agreement with the result of water uptake, proton conductivity of SPEEK/cSMM membranes also increased with temperature and was higher as compared to the corresponding SPEEK membranes; however it was still lower than that of Nafion 112. The methanol permeability values of the SPEEK/cSMM membranes were lower at different temperatures as compared to corresponding SPEEK and Nafion 112 at the same condition. Owing to considerable proton conductivity and lower methanol permeability values, SPEEK60/cSMM exhibited the highest overall performance than other tested membranes at 60°C. These results indicated that SPEEK60/cSMM membrane is promising to be used as a polymer electrolyte membrane in direct methanol fuel cell. [Copyright &y& Elsevier]

Abstract: Three different types of commercial membranes, i.e. UF PVDF100 (MWCO 100kDa), UF PES30 (MWCO 30kDa) and NF270 were used to treat car wash effluent and were evaluated with respect to permeate flux, rejection of conductivity, total dissolved solid (TDS), chemical oxygen demand (COD) and turbidity. Results revealed that NF270 exhibited greater flux stability and higher flux recovery during treatment process compared to PVDF100 and PES30 membranes, indicating its higher resistance against fouling. With respect to turbidity removal, it is found that minimum rejection of 92% could be achieved irrespective of membrane properties and effluent characteristics. The performance of membrane in COD reduction was however dependent on its properties in which NF270 showed the highest retention rate (70.9–91.5%) followed by PES30 (54.9–83.9%) and PVDF100 (56.1–82.4%). Compared to NF270, both UF membranes were found ineffective in reducing conductivity and TDS of effluent. NF270 displayed at least 60% separation rate in conductivity and TDS removal compared to 13.6–35.4% reported in PVDF100 and PES30 membranes. The features demonstrated by NF270 in separating the pollutants from the car wash effluent coupled with stable water production make the membrane a good candidate to be employed and offer an environmentally sustainable option to car wash industry. [Copyright &y& Elsevier]

Abstract: Porous asymmetric polyvinylidene fluoride (PVDF) hollow fiber membrane were fabricated via a phase-inversion method using surface modifying macromolecules (SMM) (1wt%) as the additive in the spinning dope. Distilled water and tap water were used as internal and external coagulation bath, respectively. The membranes were characterized in terms of gas permeation, wetting resistance, overall porosity, contact angle and collapsing pressure. CO2 stripping from diethanolamine (DEA) solutions was conducted through the gas–liquid membrane contactor. The effect of some operating conditions such as gas and liquid velocities, DEA concentration and rich solution temperature on the CO2 stripping flux and efficiency were investigated. By increasing liquid flow rate to 200ml.min−1, the maximum CO2 stripping efficiency of almost 82% was achieved. In addition, an increase in the liquid flow rate resulted in a significant increase of CO2 stripping flux. By increasing the liquid flow rate from 50 to 200mlmin−1, the CO2 flux increased by 900%. By increasing the gas velocity the CO2 desorption flux increased but this changing was negligible. The effect of rich solution temperature was investigated and the results showed that the CO2 desorption flux increased with increasing the solution temperature from 80 to 90°C. The results of DEA concentration enhancement on the CO2 desorption flux showed that the CO2 stripping flux increased drastically with enrichment of the DEA concentration from 1.0 to 3.0 (moll−1). Therefore, the higher stripping efficiency can be achieved by applying the higher liquid flow rate, temperature and DEA concentration in the absorbent liquid in the membrane contactor module. [Copyright &y& Elsevier]

Abstract: The fast-evolving world of nanotechnology captivates researchers in the state-of-the-art water desalination technologies. Rapid development and advancement have been reflected by a drastically increasing number of scientific investigation on the manipulation of nanomaterials in various desalination technologies. With demand rising in worldwide, the revolution of desalination technology using CNT materials to mitigate few raised over concerns, particularly energy issues, seems a viable option. In this context, this review article intends to provide an in-depth insight on the utilization of CNTs to heighten the performance of the available seawater and brackish water desalination in a holistic manner. The transport properties and chemical functionalities of this novel material to potentially facilitate excellent flux of water transport and salt rejection are outlined. Based on the computational and experimental work done over the past decade, a detailed description on the current knowledge relevant to the exploitation of CNTs in desalination has been highlighted. The current hurdles and future challenges related to this technology are then addressed. With novel properties come new opportunities for technological and commercial development. The applications of CNTs in desalination have been demonstrated and it is anticipated that applying CNTs in desalination holds very promising future prospects and will therefore lead the future direction of the realm. [Copyright &y& Elsevier]

Abstract: Microporous polyvinylidene fluoride (PVDF) hollow fiber membranes with various non-solvent additives, i.e. lithium chloride, glycerol, polyethylene glycol (PEG-400), methanol and phosphoric acid, were fabricated for CO2 stripping via membrane contactors. The membranes were characterized in terms of liquid entry pressure, contact angle, gas permeation and morphology analysis. CO2 stripping performance was investigated by using an in-house made stainless steel module with CO2-preloaded aqueous diethanolamine as the liquid absorbent. Hydrophobicity and gas permeability of the membranes reduced with the addition of a non-solvent additive in the polymer dope but increase in liquid entry pressure was observed as more sponge-like structures developed in the inner layer of the fibers. It was found that PVDF/PEG-400 membrane produced the highest stripping flux of 4.03×10−2 molm−2 s−1 which can be correlated to its high gas permeation and high effective surface porosity. The result of long-term stripping operation indicated an approximatly 80% stripping flux reduction which can be related to the interaction of polymer membrane and amine solution at high temperature. [Copyright &y& Elsevier]

Abstract: A novel surface modified Polysulfone (PSf) hollow fiber membrane was fabricated via dry–wet phased inversion process. surface modifying macromolecule (SMM) was used as additive in the spinning dope. The surface modified membrane showed large pore size, higher effective surface porosity, contact angle and porosity but lower critical water entry pressure (CEPw) compared to Polysulfone hollow fiber membrane without SMM. The performance of surface modified membrane in contactor application for CO2 absorption via distilled water as absorbent was studied. The results show that surface modified membrane has higher performance compared to plain Polysulfone membranes. With the membrane prepared from SMM in the spinning dope a maximum CO2 flux of 5.8×10−4 mol/m2 s was achieved at 300ml/min of absorbent flow rate, which was almost 76% more than the other membrane. In a long-term stability study, the initial flux reduction was found to be about 18% within the 50h of operation for surface modified membrane. [Copyright &y& Elsevier]

Abstract: A novel surface modified polyvinylidene fluoride (PVDF) hollow fiber membrane was fabricated via a dry–wet phased inversion process. A surface modifying macromolecule (SMM) was used as an additive in the spinning dope. During phase inversion SMM migrates to the membrane surface and functions as both a pore former and surface modifier. The surface modified PVDF membrane showed large pore size, higher effective surface porosity, contact angle and porosity but lower critical water entry pressure compared to the PVDF hollow fiber membrane without SMM. The performance of the surface modified membrane in contactor application for CO2 absorption via distilled water as absorbent was studied. The results show that the surface modified PVDF membrane has higher performance compared to control PVDF membranes. With the membrane prepared from SMM in the spinning dope a maximum CO2 flux of 7.7×10−4 mol/m2 s was achieved at 300ml/min of absorbent flow rate, which was almost 93% more than the other membrane.In a long-term stability study, CO2 flux was decreased only about 7.7% by using surface modified PVDF membrane during 150h operation. [Copyright &y& Elsevier]

Abstract: Porous asymmetric polyetherimide (PEI) hollow fiber membranes were fabricated via a phase-inversion method using ethanol, glycerol and acetone as the additives in the spinning dope. Also, hollow fiber PEI membrane without additives was fabricated. An aqueous solution of 1-methyl-2-pyrrolidone (80wt.%) was used as bore fluid to prevent forming of an inner dense skin layer. The precipitation rate of the polymer dopes with the different additives was studied using cloud point measurement. The effect of the additives on the resulting membrane structure, surface porosity, pore size, critical water entry pressure, collapsing pressure and physical and chemical CO2 absorption performance by distilled water and NaOH (1M) solution in a gas–liquid membrane contactor system were investigated and compared. Cloud point diagrams indicated that the precipitation rate of the polymer dopes increased following the trend of ethanol>acetone>glycerol. Results of gas permeation tests showed that ethanol and glycerol as additives provided the membranes with the largest and smallest pore size, respectively. Moreover, all the additives resulted in an increase in the effective surface porosity. The cross-section of the membranes was examined via a scanning electron microscopy. Ethanol in the spinning dope provided the membrane structure with a sublayer with finger-like macrovoids, originating from the inner and outer surfaces of the hollow fiber and extending to the middle section of the hollow fiber wall, which resulted in a larger pore size and higher CO2 absorption rate than the other PEI hollow fiber membranes. [Copyright &y& Elsevier]

Abstract: The effect of bore fluid type on the structure and performance of polyetherimide hollow fiber membranes in contactor application was investigated. Water was used as phase inversion promoter in spinning dope and water and pure NMP were used as bore fluid. SEM micrographs show that the major parts of both membranes consist of spongelike structure which is related to the high viscosity of spinning dope that reduces the diffusion of coagulant (water) into membrane sublayer and decreases the rate of phase inversion. In the case of water as bore fluid (membrane #M1) there is skin layer on the inner surface of membrane and some drop-shaped voids in the structure of membrane but in the case of pure NMP as bore fluid (membrane #M2), the inner surface of membrane is skinless with big pores and there are fingerlike macrovoids, originating from the inner surface and extending to the vicinity of outer surface which is related to the penetration of bore fluid and dissolving the polymer. Furthermore, membrane #M2 has higher mean pore size and effective surface porosity. The absorption flux of both fabricated membranes was investigated in the case of liquid in lumen side (case #1) and liquid in shell side (case #2) where in case #1, membrane #M1 has higher absorption flux but in case #2, membrane #M2 has higher absorption flux. The different trend in absorption flux confirms that the surface of membrane in contact with the gas phase in a membrane contactor should be skinless with big pores to facilitates the diffusion of solute gas through membrane but the pore size on the surface of membrane in contact with the liquid phase should be adjusted to obtain high absorption flux and low wettability. [Copyright &y& Elsevier]

Abstract: Low wettability is a vital characteristic for the membrane used in membrane contactor. Blending surface modifying macromolecule (SMM) in spinning dope is an interesting method to enhance the hydrophobicity of membrane and in this research, the effect of SMM on the properties and structure of polyetherimide (PEI) hollow fiber membrane in terms of mean pore size, liquid entry pressure of water (LEPw), membrane porosity and contact angle was investigated and compared with the properties of the PEI membrane without SMM. Furthermore the performance of PEI surface modified membrane in contactor applications in terms of CO2 absorption with distilled water was evaluated and compared with the absorption flux of PEI membrane without SMM and also, with the absorption flux of commercial and in-house made hydrophobic membranes which shows superior performance of surface modified PEI membrane e.g. in case of water in lumen side and pure CO2 in shell side of contactor and at V liquid =0.5ms−1, the absorption flux of PEI surface modified membrane is 2.94×10−3 molm−2 s−1 which is 114% higher than PEI without SMM and 73% higher than commercial membrane contactor, Celgard MiniModule® 0.75X5. [Copyright &y& Elsevier]

Abstract: High performance carbon hollow fiber membranes (CHFM) for CO2 separation were prepared by manipulating of carbonization heating rates under a N2 atmosphere. During heat treatment process, carbonization of the polymeric hollow fiber membrane was conducted up to 650°C and in the range of 1–9°C/min for heating rate. The gas permeation properties were determined using a single gas permeation apparatus at room temperature. Fine-tuning of the carbonization conditions appears necessary to obtain desired permeation properties. The gas permeance for all examined gases (N2, CH4, CO2) and selectivity of CO2/CH4 and CO2/N2 was decreased and increased, respectively, for the PEI/PVP-based CHFMs prepared at low heating rate. It was found that the heating rate posses significant effect on structure and gas permeation properties of the resultant CHFMs. Experimental results indicated that, carbonization heating rate of 3°C/min is the best conditions in the preparation of CHFMs derived from polymer blends of PEI/PVP for the CO2/CH4 and CO2/N2 separation. [Copyright &y& Elsevier]

Abstract: Porous asymmetric polysolfone (PSf) hollow fiber membranes were fabricated using wet spinning process. Glycerol (4wt.%) was used as additive. Aqueous solutions of 1-methyl-2-pyrrolidone (NMP) with different composition (0, 50, 70 and 90wt.% NMP) were used as bore fluid. Distilled water was used to preparing aqueous NMP solutions. Structure and performance of resulting membranes in measuring of surface porosity, pore size, critical water entry pressure (CEPw) and CO2 absorption in hollow fiber membrane contactor were investigated. The cross-section, the inner skin layer and the inner surface of the membranes were examined via scanning electronic microscopy (SEM). Using distilled water as bore fluid provided the membrane structure with a finger-like macrovoids which extend from the inner and outer surfaces of the membranes to the middle of the hollow fiber wall. Other hollow fiber membranes formed with a finger-like structure near the other surface and a sponge-like structure with holes beneath, which resulted in a high CEPw and CO2 absorption rate. In addition, since a mixture of distilled water and NMP was used as the neutral bore fluid, the membranes showed a skinless inner surface. Results of gas permeation tests showed with increasing NMP concentration in the bore fluid the N2 permeance decrease significantly and the wetting resistance decrease slightly. CO2 absorption by distilled water was conducted through the gas–liquid membrane contactors. By employing 90% NMP in the bore fluid, the PSf membrane showed a CO2 flux of approximately 110% higher than the PSf membrane fabricated with distilled water as the internal coagulant at the absorbent velocity of 7.9×10−4 m/s. [Copyright &y& Elsevier]

Abstract: Microporous polyvinylidene fluoride (PVDF) hollow fiber membranes were fabricated via a wet-spinning process. The prepared fibers were characterized in terms of contact angle, gas permeability, wetting pressure and morphology. CO2 stripping from preloaded aqueous diethanolamine solution was conducted through the gas–liquid membrane contactors. The effects of lithium chloride (LiCl) concentration on the membrane properties and CO2 stripping performance were investigated. The addition of different LiCl concentration resulted in a less finger-like structure, with highly effective surface porosity and high wetting pressure. Conversely, N2 permeability, contact angle value and membrane pore size were reduced as the concentration of the additives were increased. For stripping flux performance, membrane with 5wt% LiCl demonstrated the highest flux of 1.61×10−2 mol/m2 s at 110ml/min of the liquid flow rate. It was found that the membrane with less finger-like structure and higher effective surface porosity exhibited higher stripping efficiency. These results suggest that developed membrane structure can be an alternative for the CO2 stripping through gas–liquid membrane contactors. [Copyright &y& Elsevier]

Abstract: Porous asymmetric polysulfone (PSf) hollow fiber membranes were fabricated via wet spinning process. A mixture of 1-methyl-2-pyrrolidone (NMP) and distilled water (90wt.% NMP) was used as bore fluid to make hollow fiber membranes without inner skin layers, whereas glycerol with 2 and 4wt.% was used as additives to the spinning dope. The effect of the additives concentration on the structure, surface porosity, pore size, critical water entry pressure (CEPw), and CO2 absorption flux of the fabricated membranes were investigated. The cross-section and inner surface of the membranes were examined via scanning electronic microscopy (SEM). Using glycerol as the additive in the spinning dope provided the membrane structure with a thin finger-like and a thick sponge-like layer, which resulted in a high CEPw and CO2 absorption rate. Results of gas permeation tests showed with increasing glycerol concentration the N2 permeance increase significantly and the wetting resistance decrease slightly. CO2 absorption by distilled water was conducted through the gas–liquid membrane contactors. By using 4% glycerol in the spinning dope, the PSf membrane showed a CO2 flux of approximately 57% higher than the PSf membrane with 2% glycerol at the absorbent flow rate of 200ml/min. [Copyright &y& Elsevier]

Abstract: This study investigated the use of nanosized fumed silica (Aerosil® R106) as fillers in the production of asymmetric hollow fiber mixed matrix membrane (HFMMM) where polysulfone was the host polymer matrix. The presence of fumed silica particles were found to stimulate the flow of CO2 as indicated by an increase (>12%) in CO2 permeability for all HFMMMs. At low loading of 0.1% (w/w), the permeability of CO2 and CH4 were 90.04 and 2.75GPU, respectively, and the calculated selectivity was higher than the neat PSf hollow fiber membrane. At higher loading of 10% (w/w), the FESEM images of the HFMMM showed severe agglomeration of fillers that contributed to nanometric defects between the aggregates, leading to higher permeation of slow gases (CH4 and N2). Hence, the selectivities of CO2/CH4 and O2/N2 were low at 7.43 and 2.02, respectively. The calculation of particle spacing within the polymer macromolecules have shown that for nanoparticles, the agglomeration was unavoidable at high loading due to sheer number of particles within the matrix. At low loading of 0.1%, the polysulfone-fumed silica HFMMM showed no visible sign of particle agglomeration. The selectivities of CO2/CH4 and O2/N2 significantly improved with an average value of 32.74 and 6.35, respectively. The HFMMM also showed an increase in glass transition temperature and has a better thermal stability as measured by DSC and TGA analyzers, respectively. The importance of filler–filler, polymer–filler and filler–gas interactions on the characteristic and permeation performance of HFMMMs are also discussed. [Copyright &y& Elsevier]

Abstract: The influence of air bubble flow rate (ABFR), hydraulic retention time (HRT), mixed liquor suspended solid (MLSS) concentration, and pH on the performances of modified polyvinylidene fluoride (PVDF) was investigated in submerged membrane ultrafiltration (SMUF).The refinery wastewater process was conducted using an experimental set-up consisted of an SMUF reservoir, a circulation pump, and an aerator. For SMUF, operated at vacuum pressure, deposition and accumulation of suspended solids on membrane surface were prohibited with continuous aeration. The process performance was measured in terms of the membrane water flux and chemical oxygen demand (COD) removal efficiency. The air bubbles flow rate was controlled at 1.2–3.0mL/min while HRT was manipulated in the range of 120–300min. MLSS and pH solution were controlled at 4.5g/L and 6.5, respectively. Results from response surface methodology (RSM) have demonstrated the improvement in water flux and COD removal, achieving 145.7L/m2 h and 90.8%, respectively. By using pH at 6.50, the optimized conditions achieved for refinery wastewater treatment were 2.25mL/min, 276.93min, 4.50g/L for ABFR, HRT and MLSS concentration, respectively. [Copyright &y& Elsevier]

Abstract: Wetting resistance and gas permeability are the main factors for membrane contactor applications, which can be optimized according to the membrane morphology. In present study, three different types of the membrane morphology were obtained via a dry–wet spinning technique. By measuring cloud point data and viscosity, the polymer dope composition was adjusted to produce the different morphologies. The membranes with large finger-like, small finger-like and almost sponge-like morphology were obtained. The plain PVDF membrane with large finger-likes morphology presented the higher N2 permeance, lower wetting pressure and larger mean pore size (0.08μm). By addition of phosphoric acid into the spinning dope, the prepared sponge-like morphology resulted in the high surface porosity with small pore sizes, which demonstrated good permeability and wetting pressure. It was found that the mean pore size measured by gas permeation method was approximately three times larger than those from FESEM examination. CO2 stripping from water was conducted through the gas–liquid membrane contactors. The membranes with smaller pore sizes and higher wetting pressure presented higher stripping performance. In conclusion, a structurally developed PVDF hollow fiber membrane for gas–liquid contactor applications can be achieved by controlling the membrane morphology. [Copyright &y& Elsevier]

Abstract: The major breakthrough in the preparation of thin film composite (TFC) membrane via interfacial polymerization technique has resulted in tremendous achievements in producing a membrane with a right combination of flux and salt rejection, and generating huge interest in industrial sectors. Over the past decade, there have been intensive and continuous efforts in the development of TFC membrane, both from the industry and academia with the interests to further improve the membrane productivity and selectivity as well as its tolerance against chlorine, solvent, fouling, etc. On basis of a brief introduction of the development history of TFC membranes, this paper reviews the recent research progress of the TFC membrane science and technology, particularly in the fields of water-related separation processes. Reviewing the research progress is imperative and necessary in order to provide an insight for the future development and perhaps open a door to extend the applications to other more challenging areas. [Copyright &y& Elsevier]

Abstract: A novel antibacterial and anti-adhesion membrane was obtained by blending PES with 2,4,6-triaminopyrimidine (TAP) as compatibilizer and AgNO3 as an antibacterial agent. The modified membrane surfaces analyzed by XPS revealed high content of silver (Ag) compared to PES/Ag without compatibilizer. This result was supported by AFM micrographs where PES/TAP/Ag exhibited smoother surface with RMS(nm) 17.49 and Ra(nm) 11.74. From the biofouling point of view, the smoother the surface, the lesser contact area provided thus reducing bacterial adhesion. In addition, PES/TAP/Ag membrane prepared via simple phase inversion technique showed evidence of an anti-adhesion property when tested on Escherichia coli suspension of 1×104 cells/mL at 37°C. The smooth, anti-adhered surface of PES/TAP/Ag however exhibits better tensile strength up to 52% compared to pristine PES membrane, making it an antibacterial membrane with reduced biofouling potentials in water and waste water treatment. [Copyright &y& Elsevier]

Abstract: This study investigated the membrane foulants characteristics and cleaning protocol required for a poly vinylidene fluoride (PVDF) type, tubular cross flow 200kD MWCO ultrafiltration membrane fouled during natural rubber skim latex concentration process. Chemical (alkaline and acidic solutions) and physical (ultrasonic application) cleaning procedures were conducted at room temperature of 28°C and at an elevated temperature of 50°C. The membrane permeability recoveries were obtained after the end of each membrane cleaning operation, by performing deionised water flux tests (DIWFT). The extracted chemical solutions were analyzed using total organic carbon analyzer and atomic absorption spectrophotometer to quantify organic and inorganic foulants, respectively. Fourier transformation infrared attenuated total reflection spectroscopy (ATR/FTIR) was used to examine the fouled membrane surface to determine the chemical nature of the foulants. The fouled and cleaned membrane surfaces were also examined using scanning electron microscopy (SEM). The SEM images and ATR/FTIR spectrums of fouled against cleaned membranes were used to determine the efficiencies of various cleaning procedures. The measured flux recoveries using DIWFT obtained after chemical cleaning at an elevated temperature of 50°C were 93% and 89% with and without ultrasonic application, respectively. [Copyright &y& Elsevier]