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Performance of TFN nanofiltration membranes through embedding internally modified titanate nanotubes
Zeynab Fallahnejad,Gholamreza Bakeri,Ahmad Fauzi Ismail 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.7
High toxicity of water resources by heavy metal ions is common and membrane filtration is one the solutions to this problem. Titanate nanotubes (TNT) are generally used due to their unique characteristics such as mesoporous structure, and high specific surface area. In this study, the internal surface of TNT was coated through a novel in-situ polymerization method with various polymers to alter the property and size of inner surface of the nanotubes, and then was embedded in the polyamide layer of the nanofiltration membrane. The modified nanotubes were supposed to act as the channels for water transport and reject the multivalent/monovalent ions; this phenomenon was more pronounced in the modified nanotubes because of the reduction in inner diameter. Fourier transform infrared spectroscopy, X-ray diffraction and Brunauer-Emmett-Teller analysis were used to characterize the unmodified/modified nanotubes. Furthermore, the membranes were synthesized by in-situ interfacial polymerization of trimesoyl chloride and m-phenylenediamine containing 0.05 wt% nanotubes; the performance of the fabricated membranes in terms of pure water flux (PWF), contact angle, feed flux and Na+ and Cu2+ rejections was studied. Generally, incorporation of the modified nanotubes improved the trade-off between the permeation and rejection. Among the fabricated membranes, the maximum PWF was 26.13 L m2 h1 for the membrane containing 0.05 wt% polystyrene modified TNT, 71.23% more than neat thin film membrane and without any significant change in the rejection; that can be related to the hydrophilicity of the nanotube and the formation of small cavities on the membrane surface.
Development of a model for dimethyl ether non-adiabatic reactors to improve methanol conversion
Gholamreza Bakeri,Fatemeh Nasrollahi,Ahmad Fauzi Ismail,Mostafa Rahimnejad,Mahdi Imanian 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.10
The modeling of adiabatic and non-adiabatic reactors, using three cooling mediums in the shell side of a shell and tube reactor in cocurrent and countercurrent flow regimes has been conducted. The cooling mediums used in this research are saturated water and methanol feed gas to a reactor which is preheated in the shell side and a special type of oil. The results of adiabatic reactor modeling show good compatibility with the data received from a commercial plant. The results of non-adiabatic reactor modeling showed that more methanol conversion can be achieved in a lower length of reactor, even though in some cases the maximum temperature in the tube side of the reactor is more than the deactivation temperature of the catalyst.
Effect of support layer on gas permeation properties of composite polymeric membranes
Hamid Reza Afshoun,Mahdi Pourafshari Chenar,Ahmad Fauzi Ismail,Takeshi Matsuura 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.12
PES/Pebax and PEI/Pebax composite membranes were prepared by coating the porous PES and PEI substrate membranes with Pebax-1657. The morphology and performance of the prepared membranes were investigated by SEM and CO2 and CH4 permeation tests. The CO2 permeances of 28 and 52 GPU were achieved for PES/Pebax and PEI/Pebax composite membranes, respectively, with CO2/CH4 selectivities almost equal to that of Pebax (26). The experimental data were further subjected to a theoretical analysis using the resistance model. It was found that the porosity and the thickness of the dense section of PES substrate were an order of magnitude higher than those of PEI substitute. The porosity/thickness ratio of PEI substrate was, however, higher than PES, explaining the higher permeance of PEI/Pebax composite membrane. Substrates with porosities much higher than the Henis-Tripodi gas separation membrane were used in this work, aiming to achieve the selectivity of Pebax, rather than those of the substrate membrane materials.
Nur Aimie Abdullah Sani,Woei Jye Lau,Ahmad Fauzi Ismail 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.4
The performance of polyphenylsulfone (PPSU) solvent resistant nanofiltration (SRNF)-based flat sheetmembranes prepared from phase inversion method was investigated by varying the concentration of polymer in thedope solution and condition of membrane pretreatment process. The membrane properties were characterized by SEM,FTIR, AFM and contact angle goniometer, while their performance was evaluated by measuring methanol flux andrejection of different molecular weight of dyes (ranging from 269 to 1,470 g/mol) in methanol. The experimental resultsshowed that the polymer concentration has great impact not only on the final membrane morphology but also its separationcharacteristics. Increasing polymer concentration from 17 to 25wt% tended to suppress finger-like structure andmore pear-like pores were developed, causing methanol flux to decrease. This can be explained by the decrease inmolecular weight cut off (MWCO) of the membrane prepared at high polymer concentration. With respect to theeffect of membrane pretreatment conditions, the rejection of membrane was negatively affected with longer immersionperiod in methanol solution prior to filtration experiment. The variation in membrane rejection can be attributed tothe rearrangement of the polymer chain, which results in membrane swelling and/or change of membrane surfacehydrophilicity.
Noor Aina Mohd Nazri,Woei Jye Lau,Ahmad Fauzi Ismail 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.9
The effect of polyacrylonitrile-g-poly (vinyl alcohol) (PAN-g-PVA) copolymer additive on the properties of PAN-based hollow fiber UF membranes was studied. The resulting hollow fiber membranes were characterized with respect to structural morphology, surface properties, and proteins rejection in order to investigate the impact of PAN-g- PVA copolymer composition (presented at different PAN: PAN-g-PVA ratio) in the UF membrane on the separation and antifouling properties. Results showed that the hollow fiber membrane prepared from the highest composition of PAN-g-PVA copolymer (PAN: PAN-g-PVA 80 : 20) was able to produce pure water flux as high as 297 L/m2·hr in comparison to 41 L/m2·hr reported in control PAN membrane when tested at 1 bar. Fouling experiments performed using bovine serum albumin (BSA), albumin from chicken egg (CE) and trypsin indicated that the blend membranes with higher surface coverage of hydrophilic PVA (34-60%) were more excellent in minimizing protein fouling, which might be correlated with the formation of hydrophilic PVA layer on their surface. Although increase in membrane hydrophilicity upon PAN-g-PVA copolymer incorporation might be the main reason contributing to improved membrane antifouling properties, the changes in membrane surface roughness and pore size could not be completely ruled out to influence membrane anti-fouling resistance during protein filtration.
Gholamreza Bakeri,Masoud Rezaei-DashtArzhandi,Ahmad Fauzi Ismail,Takeshi Matsuura,Mohd Sohaimi Abdullah,Ng Be Cheer 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.1
A membrane contactor (MC) is used for natural gas sweetening and wastewater treatment with a membrane that is acting as a separating barrier between two phases, usually liquid and gas. The performance of membrane is governed by parameters such as pore size, porosity, tortuosity and surface hydrophobicity, which can be controlled by a number of methods. Addition of nonsolvents to spinning solution is known to be one of such methods. In this study, the effects of low molecular weight additives as phase inversion promoters on the morphology of polyethersulfone hollow fiber membranes and their performance in gas-liquid MC processes were investigated. It was found that among the six nonsolvent additives under study, addition of water resulted in the highest CO2 flux, by decreasing the thermodynamic stability of polymer solution and maintaining high solvent-nonsolvent exchange rate.
Faten Ermala Che Othman,Sadaki Samitsu,Norhaniza Yusof,Ahmad Fauzi Ismail 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.11
A simple, promising, environmentally friendly, and high yield technique to synthesize high specific surface area (SSA) and porous graphene-like materials from glucose precursor through carbonization and controlled chemical iron chloride (FeCl3) activation was demonstrated. Designing this nanoporous graphene-based adsorbent with high SSA, abundant micropore volume, tunable pore size distribution, and high adsorption capacity, is crucial in order to deal with the demands of large-scale reversible natural gas storage applications. Raman spectroscopy, BET method of analysis, and N2 adsorption/desorption measurements at 196 oC were adopted to evaluate the structural and textural properties of the resultant glucose derived-graphene (gluGr) samples. The effects of different carbonization conditions, such as the inert environments (argon, helium, and argon) and temperatures (700, 800, 900, and 1,000 oC), have been studied. A glucose-derived graphene carbonized under nitrogen environment at 700 oC (NGr700) with highly interconnected network of micropores and mesopores and large SSA (767m2/g) exhibited excellent methane (CH4) storage property with exceptionally high adsorption capacity, superior to other glucose-derived graphene (gluGr) samples. A maximum volumetric capacity up to 42.08 cm3/g was obtained from CH4 adsorption isotherm at 25 oC and 35 bar. Note that the adsorption performance of the CH4 is highly associated with the SSA and microporosity of the gluGr samples, especially NGr700 that was successfully synthesized by FeCl3 activation under N2 environment.
Nurasyikin Misdan,Woei Jye Lau,Chi Siang Ong,Ahmad Fauzi Ismail,Takeshi Matsuura 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.4
Three composite nanofiltration (NF) membranes made of different substrate materials--polysulfone (PSf),polyethersulfone (PES) and polyetherimide (PEI)--were successfully prepared by interfacial polymerization technique. Prior to filtration tests, the composite NF membranes were characterized using field emission scanning electron microscope(FESEM), atomic force microscope (AFM) and X-ray photoelectron spectroscope (XPS). It was observed that thesurface properties of composite NF membranes were obviously altered with the use of different substrate materials. Theseparation performance of the prepared composite NF membranes was further evaluated by varying operating conditions,which included feed salt concentration and operating temperature. Experimental results showed that the waterflux of all TFC membranes tended to decrease with increasing Na2SO4 concentration in feed solution, due to the increasein feed osmotic pressure. Of the three TFC membranes studied, PSf-based membrane demonstrated the highestsalt rejection but lowest water flux owing to its highest degree of polyamide cross-linking as shown in XPS data. Withrespect to thermal stability, PEI-based TFC membrane outperformed the rest, overcoming the trade-off effect betweenpermeability and rejection when the feed solution temperature was gradually increased from 30 oC to 80 oC. In addition,the relatively smoother surface of hydrophilic PEI-based membrane when compared with PSf-based membranewas found to be less susceptible to BSA foulants, leading to lower flux decline. This is because smoother surface ofpolyamide layer would have minimum “valley clogging,” which improves membrane anti-fouling resistance.
Muhazri Abd Mutalib,Farhana Aziz,Nur Aisyah Jamaludin,Norsyazwani Yahya,Ahmad Fauzi Ismail,Mohamad Azuwa Mohamed,Mohd Zamri Mohd Yusop,Wan Norharyati Wan Salleh,Juhana Jaafar,Norhaniza Yusof 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.2
Perovskite LaFeO3 photocatalyst prepared by using sol-gel glucose method was assembled on graphene oxide sheets to produce integrated photocatalyst-adsorbents (IPCA) and investigated as photocatalyst for the degradation of methylene blue under visible light irradiation. The prepared photocatalyst was characterized by FTIR, XRD, FESEM, BET specific surface area measurement, TEM/HRTEM and UV-Vis spectroscopy analysis. The FTIR, FESEM and TEM analysis has suggested that the photocatalyst LaFeO3 has been successfully embedded at the surface of the graphene oxide (GO) sheets due to a strong interaction between the photocatalyst and the adsorbents matrix. Methylene blue degradation shows that IPCA possesses higher photodegradation kinetics compared to bare LaFeO3 photocatalyst. The resultant photocatalyst also possesses magnetic properties which can overcome the difficulty in recollecting and removal of photocatalyst suspension in water after photocatalytic treatment.