Synthesis Of Buckypaper Supported Ionic Liquid Membrane For Pervaporation Process

Membran cecair berpenyokong adalah salah satu konfigurasi membran cecair yang menggunakan bahan fasa cecair sebagai membran dan diperangkap ke dalam substrat berliang. Sejak kebelakangan ini, idea tentang penggunaan membran cecair berpenyokong dalam proses penyejattelapan telah menarik tumpuan ramai penyelidik. Tetapi penggunaan membran cecair berpenyokong menghadapi masalah ketidakstabilan yang berpunca daripada kehilangan membran cecair. Kajian ini bertujuan untuk membangunkan membran cecair berpenyokong dengan kestabilan yang tinggi dengan menggunakan kertas-bucky sebagai substrat berliang dan diperangkap dengan cecair ionik 1-butil-metilimidazolium tetrafluoroborat [Bmim][BF4] untuk membentuk membran cecair ionik berpenyokong kertas-bucky. Kertas-bucky terdiri daripada kelompok nano-tiub karbon dinding berlapis mampu memerangkap membran cecair ionik secara berkesan disebabkan oleh saiz liang yang kecil and struktur liang yang berliku-liku. Untuk meningkatkan lagi kestabilan membran, [Bmim][BF4] telah dicampur dengan polivinil alkohol sebelum diperangkap dalam kertas-bucky. Struktur membran cecair ionik berpenyokong kertas-bucky yang terhasil didapati berbeza dengan membran asimetrik, di mana fasa membran dan sokongan telah digabungkan dalam satu lapisan. Struktur tersebut membolehkan pembentukan membran simetri yang tipis tanpa menjejaskan sifat mekanikal membran. Prestasi membran cecair ionik berpenyokong kertas-bucky dalam proses penyejattelapan yang melibatkan campuran perduaan yang terdiri daripada etilena glikol dan air menunjukkan keupayaan membran tersebut dalam penyahhidratan larutan akueus etilena glikol. Kewujudan kertas-bucky dan [Bmim][BF4] didapati telah meningkatkan prestasi pemisahan dan kebolehtelapan intrinsik membran. Membran cecair ionik berpenyokong kertas-bucky telah menunjukkan prestasi penyejattelapan yang tinggi dengan fluks penelapan yang bernilai 102 g∙m-2∙j-1, faktor pemisahan setinggi 1014, kebolehtelapan air yang bernilai 13106 GPU dan kememilihan membran untuk air yang bernilai 13 dengan berat air dalam kepekatan larutan suapan sebanyak 10% pada suhu 30 °C dan 5 mmHg tekanan hiliran. Di samping itu, membran cecair ionik berpenyokong kertas-bucky juga mampu untuk memisahkan campuran pertigaan; etil asetat, etanol dan air yang membentuk azeotrop. Fluks penelapan sebanyak 385 g∙m-2∙j-1, faktor pemisahan yang bernilai 247, kebolehtelapan air 4730 GPU dan kememilihan membran untuk air yang bernilai 39 telah diperolehi pada suhu 30 °C dan 5 mmHg tekanan hiliran. Membran cecair ionik berpenyokong kertas-bucky telah mempamerkan prestasi yang tekal dalam operasi selama 120 jam. Pekali resapan etilena glikol dan air pada operasi parameter yang berlainan telah dianggar dengan menggunakan model matematik semi-empirikal berdasarkan pengubahsuaian persamaan Maxwell-Stefan. Dengan merujuk pada pekali resapan yang dianggar, pemisahan membran cecair ionik berpenyokong kertas-bucky dalam proses penyejahttelapan bagi penyahhidratan campuran perduaan etilena glikol/air adalah dikawal oleh proses resapan. ________________________________________________________________________________________________________________________ Supported liquid membrane (SLM) is one of the liquid membrane configurations that employ a liquid phase substances as membrane and immobilized in a porous supporting membrane. Recently, the idea of using SLM in pervaporation process has attracted a great deal of research attention. However the use of SLM in pervaporation has always suffered from instability problem which is mainly due to the displacement of liquid membrane. In the present research work, it is aimed to develop a high stability SLM by employing buckypaper (BP) as supporting membrane and immobilized with an ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate [Bmim][BF4] to form a buckypaper supported ionic liquid membrane (BP-SILM). The BP, which is composed of entangled assemblies of multi-walled carbon nanotubes (CNTs), can effectively entrap the infiltrated the ionic liquid membrane due to its smaller pore size and highly tortuous porous structure. In order to further enhance the membrane stability, the [Bmim][BF4] was blended with polyvinyl alcohol (PVA) prior to the immobilization in the BP. The resulted BP-SILM structure, in which the membrane and support phase were merged into a single layer, was found to be different from that of conventional asymmetric membranes. The BP-SILM structure allows the formation of a thinner symmetric membrane without compromising its mechanical properties. The pervaporation performances of the BP-SILM in the binary mixture of ethylene glycol and water showed an excellent capability to dehydrate ethylene glycol aqueous solutions. The presence of BP and [Bmim][BF4] was observed to significantly enhance the separation performance and the intrinsic membrane permeability. The BP-SILM exhibited high pervaporation performance with a permeation flux of 102 g∙m-2∙h-1, separation factor as high as 1014, water permeance of 13106 GPU and membrane selectivity of 13 for water with 10 wt.% feed concentration of water at 30 °C and 5 mmHg downstream pressure. On the other hand, the BP-SILM was also capable to break ternary azeotropic mixtures of ethyl acetate, ethanol and water. A permeation flux of 385 g∙m-2∙h-1, separation factor of 247, water permeance of 4730 GPU and membrane selectivity of 39 for water were obtained at 30 °C and 5 mmHg downstream pressure. The BP-SILM also demonstrated a robust pervaporation performance over an operation of 120 hours. The diffusion coefficients of ethylene glycol and water at different operating parameter were estimated using a semi-empirical mathematical model based on modified Maxwell-Stefan equation. Based on the estimated diffusion coefficient obtained, the separation of BP-SILM in pervaporation dehydration of ethylene glycol/water binary mixture is more on diffusion control

Modification Of Multi-Walled Carbon Nanotubes For Pervaporation Nanocomposite Membrane

Pervaporasi semakin mendapat perhatian dalam teknologi pemisahan membran kerana penggunaan tenaga yang rendah, operasi dan kawalan yang mudah. Owing to its low energy consumption, operational simplicity and ease of control, pervaporation has gained increasing interest in membrane separation technolog

Improved miscibility and toughness of biological poly(3-hydroxybutyrate-co-4-hydroxybutyrate)/poly (lactic acid) blends via melt-blending-induced thermal degradation,

Polymer blending has been a facile method to resolve the brittle issue of poly(lactic acid) (PLA). Yet, miscibility becomes the primary concern that would affect the synergy effect of polymer blending. This study aimed to improve the miscibility of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB) and PLA by lowering their molecular weights via a melt-blending-induced thermal degradation during mechanical mixing to form m-P34HB/PLA blends. The molecular weight of the P34HB was significantly reduced after blending, thereby improving the miscibility of the blends, as evidenced by the shift of glass transition temperatures. Also, simulation based on Flory-Huggins theory demonstrated increased miscibility with decreasing molecular weight of the polymers. Moreover, the thermal gravimetric analysis revealed that the PLA provided a higher shielding effect to the P34HB in the blends prepared by melt-blending than those by solution-blending, that the addition of PLA could retard the chain scission of P34HB and delay its degradation. The addition of m-P34HB at 20 wt% in the blend contributed to a 60-fold enhancement in the elongation at break and an increment of 4.6 folds in the Izod impact strength. The enzymatic degradation using proteinase K revealed the preferential to degrade the PLA in the blends and followed the surface erosion mechanism.補正完畢NL

A review on carbon nanotubes in an environmental protection and green engineering perspective

Recent developments in nanotechnologies have helped to benchmark carbon nanotubes (CNTs) as one of the most studied nanomaterials. By taking advantages of CNTs extraordinary physical, chemical and electronic properties, a wide variety of applications has been proposed in various engineering fields. In this short review, the contribution of CNTs is addressed in terms of sustainable environment and green technologies perspective, such as waste water treatment, air pollution monitoring, biotechnologies, renewable energy technologies, supercapacitors and green nanocomposites. Consideration of CNTs for large scale application from the aspect of cost and potential hazards are also discussed. Based on the literature studied, CNTs pose a great potential as a promising material for application in various environmental fields

Modified Zeolite/Polysulfone Mixed Matrix Membrane for Enhanced CO2/CH4 Separation

[[abstract]]In recent years, mixed matrix membranes (MMMs) have received worldwide attention for their potential to offer superior gas permeation and separation performance involving CO2 and CH4. However, fabricating defect-free MMMs still remains as a challenge where the incorporation of fillers into MMMs has usually led to some issues including formation of undesirable interfacial voids, which may jeopardize the gas separation performance of the MMMs. This current work investigated the incorporation of zeolite RHO and silane-modified zeolite RHO (NH2–RHO) into polysulfone (PSf) based MMMs with the primary aim of enhancing the membrane’s gas permeation and separation performance. The synthesized zeolite RHO, NH2–RHO, and fabricated membranes were characterized by X-ray diffraction (XRD) analysis, Fourier transform infrared-attenuated total reflection (FTIR-ATR), thermogravimetric analysis (TGA) and field emission scanning election microscopy (FESEM). The effects of zeolite loading in the MMMs on the CO2/CH4 separation performance were investigated. By incorporating 1 wt% of zeolite RHO into the MMMs, the CO2 permeability and ideal CO2/CH4 selectivity slightly increased by 4.2% and 2.7%, respectively, compared to that of a pristine PSf membrane. On the other hand, a significant enhancement of 45% in ideal CO2/CH4 selectivity was attained by MMMs incorporated with 2 wt% of zeolite NH2-RHO compared to a pristine PSf membrane. Besides, all MMMs incorporated with zeolite NH2-RHO displayed higher ideal CO2/CH4 selectivity than that of the MMMs incorporated with zeolite RHO. By incorporating 1–3 wt% zeolite NH2-RHO into PSf matrix, MMMs without interfacial voids were successfully fabricated. Consequently, significant enhancement in ideal CO2/CH4 selectivity was enabled by the incorporation of zeolite NH2–RHO into MMMs.[[notice]]補正完

Energy and environmental applications of carbon nanotubes

Energy and environment are major global issues inducing environmental pollution problems. Energy generation from conventional fossil fuels has been identified as the main culprit of environmental quality degradation and environmental pollution. In order to address these issues, nanotechnology plays an essential role in revolutionizing the device applications for energy conversion and storage, environmental monitoring, as well as green engineering of environmental friendly materials. Carbon nanotubes and their hybrid nanocomposites have received immense research attention for their potential applications in various fields due to their unique structural, electronic and mechanical properties. Here, we review the applications of carbon nanotubes (1) in energy conversion and storage such as in solar cells, fuel cells, hydrogen storage, lithium ion batteries and electrochemical supercapacitors, (2) in environmental monitoring and wastewater treatment for the detection and removal of gas pollutants, pathogens, dyes, heavy metals and pesticides and (3) in green nanocomposite design. Integration of carbon nanotubes in solar and fuel cells has increased the energy conversion efficiency of these energy conversion applications, which serve as the future sustainable energy sources. Carbon nanotubes doped with metal hydrides show high hydrogen storage capacity of around 6 wt% as a potential hydrogen storage medium. Carbon nanotubes nanocomposites have exhibited high energy capacity in lithium ion batteries and high specific capacitance in electrochemical supercapacitors, in addition to excellent cycle stability. High sensitivity and selectivity towards the detection of environmental pollutants are demonstrated by carbon nanotubes based sensors, as well as the anticipated potentials of carbon nanotubes as adsorbent to remove environmental pollutants, which show high adsorption capacity and good regeneration capability. Carbon nanotubes are employed as reinforcement material in green nanocomposites, which is advantageous in supplying the desired properties, in addition to the biodegradability. This article presents an overview of the advantages imparted by carbon nanotubes in electrochemical devices of energy applications and green nanocomposites, as well as nanosensor and adsorbent for environmental protection