Remotely Operated Vehicle (ROV) diving equipment system is an important device in oil and gas exp... more Remotely Operated Vehicle (ROV) diving equipment system is an important device in oil and gas exploration and production, especially in the conditions of working in deep and complex waters. By design, the ROV Panther Plus 932 has no reverse steering function, limited visibility and difficult operation. To overcome that shortcoming, the authors have studied and fabricated an electronic circuit to take charge of the power reversing function on the Joystick with a function button and a Forward/Revert status indicator light. After adjusting, designing, controlling the ROV in the opposite direction, there is no need to turn the head, avoid twisting, burning cables, getting caught in obstacles or being caught up in the ROV during work, increasing cable life.
Silica aerogels have attracted great attention owing to their outstanding properties such as ultr... more Silica aerogels have attracted great attention owing to their outstanding properties such as ultralow density, high porosity, high surface area, and low thermal conductivities. Their poor mechanical properties and hydrophilicity constrain their practical applications. In this work, phenyltrimethoxysilane (PTMS) and polyvinyl alcohol (PVA) were added into methyltrimethoxysilane (MTMS)-based silica aerogels to enhance their mechanical properties. It was found that PTMS considerably improved the hydrophobicity of MTMS silica aerogels with an increase in water contact angles from 115° to 150°. The addition of PVA considerably increased the hardness, morphology, density, porosity, surface area, and thermal conductivity of MTMS silica aerogels. When PVA concentration was increased from 0 to 2 %, the aerogel hardness, density, and thermal conductivity were also increased from 0 to 14 %, 0.072 to 0.11 g/cm3, and 0.035 to 0.046 W/m.K. In contrast, the aerogel became less porous and the poros...
Journal of Material Cycles and Waste Management, 2021
Over 60 million tons of aluminium are produced annually, requiring sustainable and eco-friendly r... more Over 60 million tons of aluminium are produced annually, requiring sustainable and eco-friendly recycling methods of aluminium waste. In this work, aluminium metal waste is utilized in the fabrication of aluminium hydroxide aerogels using a cost-effective and environmental-friendly process. The developed aerogels with varying contents of aluminium and poly(vinyl alcohol) as a binder exhibit a low density (0.060–0.108 g/cm3), a high porosity (92.3–95.5%) and a low electrical conductivity ([1.8–5.2] × 10–8 S/m). The results indicated that aluminium hydroxide aerogels have an ultra-low thermal conductivity of 0.028–0.032 W/m K and are able to withstand high temperature of 800 °C with less than 50% decomposition. It is suggested that the synthesized aerogels can be a promising candidate for high-value engineering applications such as thermal insulation of pipes and buildings to expand the usage of recycled aluminium.
Australasian Business, Accounting and Finance Journal, 2021
We extend current literature by providing empirical evidence on the impacts of financial reportin... more We extend current literature by providing empirical evidence on the impacts of financial reporting quality and corporate governance mechanism - two firm-level determinants that are strongly affected by the unique market setting and regulatory framework in emerging/frontier markets - and idiosyncratic risk in Vietnam. Utilizing different panel data analysis techniques, we find high-quality financial reports can mitigate firm-specific risk. Firms with high state ownership tend to have lower idiosyncratic risk too, implying the monitoring role of the government. We also document a positive link between board size and firm specific risk. Our results are thus beneficial for industry regulators and firms in ensuring good governance and reporting framework to better manage firm risk.
Massive quantities of fly ash are produced worldwide from thermal power plants, posing a serious ... more Massive quantities of fly ash are produced worldwide from thermal power plants, posing a serious environmental threat due to their storage and disposal problems. In this study, for the first time, fly ash is converted into an advanced and novel aerogel through a green and eco-friendly process. The developed aerogel has a low density of 0.10-0.19 g cm-3, a high porosity of up to 90%, a low thermal conductivity of 0.042-0.050 W/mK, and a good sound absorption coefficient (noise reduction coefficient [NRC] value of 0.20-0.30). It also shows a high compressive Young's modulus of up to 150 kPa. Therefore, the newly developed fly ash aerogel is a potential material for thermal and acoustic insulation applications, along with lightweight composites in automotive and aerospace applications.
Journal of Environmental Chemical Engineering, 2020
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Journal of Environmental Chemical Engineering, 2020
Petroleum spills have been described as one of the leading aquatic disasters that has resulted in... more Petroleum spills have been described as one of the leading aquatic disasters that has resulted in the destruction and degradation of marine ecosystems worldwide, destroying the lives of thousands of organisms within a short period. Parts of the causes of this may be linked to waste products from plastics and rubber tires. This study focuses on fibers from rubber tires, and successfully produces rubber aerogels from them using glutaraldehyde and poly(vinyl alcohol) binders, followed by a freeze-drying process. Our recycled rubber aerogels are extremely pore (92.2-98.3 %) and ultra-low density (0.020−0.091 g/cm 3). After a methyltrimethoxysilane (MTMS) coating, rubber aerogels show their super-hydrophobic properties with a water contact angle up to 153°. The effects of rubber fiber and cross-linker contents on the rubber aerogel oil absorption efficiency are thoroughly investigated. Pseudo-first-order and pseudo-second-order kinetics are studied for the absorption of rubber aerogel and the result shows that the pseudo-second-order model could better predict oil absorption performance. A maximum rubber aerogel oil absorption of up to 25.0 g/g is estimated, approximately 1.7 and 2.8 times higher compared to commercial polypropylene mat and nonwoven polypropylene, respectively. Such a material can play an instrumental role towards recycling of car tires and paves the way for maximizing the recycling capacity of waste rubber tires globally. This will in turn reduce the global and environmental impact of waste pollution associated with untreated car tires.
Over twenty million tons of pineapples have been produced annually worldwide, but their waste is ... more Over twenty million tons of pineapples have been produced annually worldwide, but their waste is mostly discarded or burnt after harvesting. In this work, the high-value added aerogels from the pineapple leaf waste are developed for the first time by using polyvinyl alcohol (PVA) cross-linkers and a cost-effective freeze drying process. The pineapple fibre (PF) aerogels have highly porous structures with the porosities of 96.98-98.85%, ultra-low densities of 0.013-0.033 g/cm 3 , and hydrophobicity with water contact angles of approximately 140°, after a surface modification with methyltrimethoxysilane (MTMS). The effects of PF concentrations (0.5-2.0 wt. %) on oil and organic solvent adsorption are investigated comprehensively. Experimental results indicate that the hydrophobic PF aerogels can adsorb motor oil up to 37.9 g/g, approximately two times greater than commercial polypropylene and polyurethane sorbents. The pseudo-second order model can provide a good fit for the oild adsorption kinetics of the developed aerogels.
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Millions of tons of plastic are produced annually, but less than 10% are reported to be recycled.... more Millions of tons of plastic are produced annually, but less than 10% are reported to be recycled. This work sets out to transform environmental plastic (polyethylene terephthalate-PET) waste into aerogels for high-value engineering applications, primarily to enhance the monetary incentive in recycling plastics. Coating techniques, using silicone ceramic (SCC) and (3-aminopropyl)triethoxysilane (APS, or APTES) solutions, are successfully devised to enhance the thermal stability and CO 2 adsorption capability of rPET aerogel. The rPET/SCC aerogel exhibits improved thermal stability (up to 600°C), enhanced thermal insulation (thermal conductivity K avg = [31.8-34.9] mW/mÁK), hydrophobic characteristics (up to 144.7°i n contact angle) and enhanced rigidity (Young modulus E avg = [4.5-124.8] kPa), while maintaining an ultra-low density (q a = [14-62] g/cm 3) and a high porosity (U avg = [95.6-99.0]%). Moreover, the aminefunctionalised rPET aerogel achieves a CO 2 adsorption capacity of up to 0.44 mmol CO 2 /g, superior to several commercial physio-sorbents. These promising results obtained demonstrate that the rPET aerogel is a versatile material suitable for a wide variety of high-value engineering applications, including thermal insulation and direct CO 2 capture applications.
Exercising in a tropical climate with constant high temperatures and high humidity increases the ... more Exercising in a tropical climate with constant high temperatures and high humidity increases the risk of heatstroke for active people who frequently train outdoors. For these active persons, a cooling source of water nearby can be essential, and this is usually carried in canteen bottles. However, commercially available water canteen bottles have limited thermal insulation capability to keep the liquid content cooled for the required period. This work proposed an engineering solution to enhance the heat insulation performance of water canteen bottles, using recycled cellulose aerogels made from paper waste for the first time as an insulating layer. Recycled cellulose aerogels wrapped around the water canteen bottle provides excellent thermal insulation performance, while not adding significant weight to the bottle. The temperature of the ice slurry in the canteen bottle was measured periodically over four hours with a mercury thermometer. The effects of the static and dynamic condit...
� Recycled PET is converted into an aerogel by an advanced and cost-effective method. � The mater... more � Recycled PET is converted into an aerogel by an advanced and cost-effective method. � The material has high oil absorption capacities of 46-80 times of its weight. � Aerogel presents good absorption capacity with different pollutant organic solvents. � Oil absorption kinetics are investigated by pseudo-first and-second order models. � The rPET aerogels present a good elasticity with low elastic modulus.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2019
For the first time, recycled car tire fibers (RCTF) shredded from car tire waste are developed su... more For the first time, recycled car tire fibers (RCTF) shredded from car tire waste are developed successfully into a novel material, a rubber aerogel, using polyvinyl alcohol (PVA) and glutaraldehyde (GA) as crosslinkers through a cost-effective freeze-drying method. Its structure and main physical properties are investigated comprehensively for high-value applications, such as heat and sound insulation of buildings and oil spill spilling clean up. The rubber aerogel has ultra-low density (ρ a = 0.035-0.145 g/cm 3) and high porosity (Φ avg = 84.31-96.20 %). With a simple but effective coating method with methoxytrimethylsilane (MTMS), both the interior and exterior of the whole rubber aerogel surface can be well coated, and the coated aerogel exhibits a super-hydrophobicity with a water contact angle of up to 134.4°. The rubber aerogel exhibits excellent heat insulation properties (K avg = 0.035-0.047 W/m.K), very good thermal stability up to 500°C, and significantly-enhanced rigidity up to a Young modulus of E avg = 458.12 kPa, much larger than that of commercial Styrofoam. The rubber aerogel shows very good durability as it springs back to its original shape after compression tests. The rubber aerogel has a noise reduction coefficient (NRC) of 0.41 and performs approximately 10% better than commercial sound foam absorber at 2000-3000 Hz. The maximum oil absorbtion capacity of the rubber aerogel in this work is 19.3 g/g, very competitive to commercial sorbents. The fabrication method can also be scaled up for several other industrial applications, not limited to sound, heat and sorbent applications.
This work presents for the first time, a simple, practical and scalable approach to fabricating r... more This work presents for the first time, a simple, practical and scalable approach to fabricating recycled polyethylene terephthalate (rPET) aerogels for thermal and acoustic insulation applications. The rPET aerogels were successfully developed from recycled PET fibers and polyvinyl alcohol (PVA) and glutaraldehyde (GA) cross-linkers using a freeze-drying process. The effects of various PET fiber concentrations (0.5, 1.0 and 2.0 by wt.%), fiber deniers (3D, 7D and 15D) and fiber lengths (32 mm and 64 mm) on the rPET aerogel structures and multi-properties were comprehensively investigated. The developed rPET aerogels showed a highly porous network structure (98.3-99.5%), ultra-low densities (0.007-0.026 g/cm 3), hydrophobicity with water contact angles of 120.7-149.8 • , and high elasticity with low compressive Young's modulus (1.16-2.87 kPa). They exhibited superior thermal insulation capability with low thermal conductivities of 0.035-0.038 W/m.K, which are highly competitive with recycled cellulose and silica-cellulose aerogels and better than mineral wool and polystyrene. The acoustic absorption results were also found to outperform a commercial acoustic foam absorber across a range of frequencies.
With the aim of introduction a new inexpensive co-adsorbent to improve solar cell performance, th... more With the aim of introduction a new inexpensive co-adsorbent to improve solar cell performance, the influence of nicotinic acid (NTA) used as a co-adsorbent in dye-sensitized solar cells (DSCs) was investigated. The findings showed that low concentrations of NTA (<10 mM) increased the N719 ruthenium dye loading on the TiO 2 electrode surface by 10-12%, whereas higher concentrations of NTA lowered the dye loading. The adsorption of NTA onto the TiO 2 electrode surface was studied by attenuated total reflectance Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, and the blocking effect of NTA toward electron transfer between the electrode and 1,4-dicyanonaphthalene (redox couple electrolyte probe) was investigated by cyclic voltammetry. Subsequently, the performance of NTA in functional DSCs was evaluated by current-voltage (J-V) DSC characterization and compared with that of DSCs fabricated with two well-established co-adsorbents i.e., chenodeoxycholic acid (CDA) and octadecylphosphonic acid (OPA). The findings showed that under optimized co-adsorbent concentration (1 mM NTA, 0.03 mM CDA, 0.015 mM OPA), the efficiency of the corresponding solar cells increased to the same extent. Specifically, the use of NTA at optimum concentration improved the efficiency of the resulting DSC from 3.14 to 5.02%.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2016
Silica-cellulose aerogels were successfully developed from recycled cellulose fibres and methoxyt... more Silica-cellulose aerogels were successfully developed from recycled cellulose fibres and methoxytrimethylsilane (MTMS) silica precursor for the first time. The silica-cellulose aerogels showed the super-hydrophobicity with an average water contact angle of 151 o. The silica-cellulose aerogels developed in this work showed a promising potential for thermal and acoustic insulation applications. This work provides a facile approach to fabricate cost-effective silica-cellulose aerogels with industrial dimensions.
Although α-diazo-β-ketoesters are synthetically versatile intermediates, methodology for introduc... more Although α-diazo-β-ketoesters are synthetically versatile intermediates, methodology for introducing this functionality into complex molecules is still limited, most frequently involving a carboxylic acid precursor, which is then activated and transformed into a β-ketoester, with the diazo group being subsequently added with a diazo transfer reagent. While introducing this highly functional moiety in a convergent one step process would be ideal, such an objective is limited by the relatively few studies which address functionalization of the α-diazo-β-ketoester at the γposition. In the present investigation, we evaluate strategies, both new and established, for functionalizing α-diazo-β-ketoesters, particularly with regard to generating compounds prospectively useful in the synthesis of C1-substituted carbapenems. We report the first δaldehydo-α-diazo-β-ketoester as well as a method for its oxidation to the corresponding methyl ester, and the formation of a new substituted pyrazole under basic conditions.
Remotely Operated Vehicle (ROV) diving equipment system is an important device in oil and gas exp... more Remotely Operated Vehicle (ROV) diving equipment system is an important device in oil and gas exploration and production, especially in the conditions of working in deep and complex waters. By design, the ROV Panther Plus 932 has no reverse steering function, limited visibility and difficult operation. To overcome that shortcoming, the authors have studied and fabricated an electronic circuit to take charge of the power reversing function on the Joystick with a function button and a Forward/Revert status indicator light. After adjusting, designing, controlling the ROV in the opposite direction, there is no need to turn the head, avoid twisting, burning cables, getting caught in obstacles or being caught up in the ROV during work, increasing cable life.
Silica aerogels have attracted great attention owing to their outstanding properties such as ultr... more Silica aerogels have attracted great attention owing to their outstanding properties such as ultralow density, high porosity, high surface area, and low thermal conductivities. Their poor mechanical properties and hydrophilicity constrain their practical applications. In this work, phenyltrimethoxysilane (PTMS) and polyvinyl alcohol (PVA) were added into methyltrimethoxysilane (MTMS)-based silica aerogels to enhance their mechanical properties. It was found that PTMS considerably improved the hydrophobicity of MTMS silica aerogels with an increase in water contact angles from 115° to 150°. The addition of PVA considerably increased the hardness, morphology, density, porosity, surface area, and thermal conductivity of MTMS silica aerogels. When PVA concentration was increased from 0 to 2 %, the aerogel hardness, density, and thermal conductivity were also increased from 0 to 14 %, 0.072 to 0.11 g/cm3, and 0.035 to 0.046 W/m.K. In contrast, the aerogel became less porous and the poros...
Journal of Material Cycles and Waste Management, 2021
Over 60 million tons of aluminium are produced annually, requiring sustainable and eco-friendly r... more Over 60 million tons of aluminium are produced annually, requiring sustainable and eco-friendly recycling methods of aluminium waste. In this work, aluminium metal waste is utilized in the fabrication of aluminium hydroxide aerogels using a cost-effective and environmental-friendly process. The developed aerogels with varying contents of aluminium and poly(vinyl alcohol) as a binder exhibit a low density (0.060–0.108 g/cm3), a high porosity (92.3–95.5%) and a low electrical conductivity ([1.8–5.2] × 10–8 S/m). The results indicated that aluminium hydroxide aerogels have an ultra-low thermal conductivity of 0.028–0.032 W/m K and are able to withstand high temperature of 800 °C with less than 50% decomposition. It is suggested that the synthesized aerogels can be a promising candidate for high-value engineering applications such as thermal insulation of pipes and buildings to expand the usage of recycled aluminium.
Australasian Business, Accounting and Finance Journal, 2021
We extend current literature by providing empirical evidence on the impacts of financial reportin... more We extend current literature by providing empirical evidence on the impacts of financial reporting quality and corporate governance mechanism - two firm-level determinants that are strongly affected by the unique market setting and regulatory framework in emerging/frontier markets - and idiosyncratic risk in Vietnam. Utilizing different panel data analysis techniques, we find high-quality financial reports can mitigate firm-specific risk. Firms with high state ownership tend to have lower idiosyncratic risk too, implying the monitoring role of the government. We also document a positive link between board size and firm specific risk. Our results are thus beneficial for industry regulators and firms in ensuring good governance and reporting framework to better manage firm risk.
Massive quantities of fly ash are produced worldwide from thermal power plants, posing a serious ... more Massive quantities of fly ash are produced worldwide from thermal power plants, posing a serious environmental threat due to their storage and disposal problems. In this study, for the first time, fly ash is converted into an advanced and novel aerogel through a green and eco-friendly process. The developed aerogel has a low density of 0.10-0.19 g cm-3, a high porosity of up to 90%, a low thermal conductivity of 0.042-0.050 W/mK, and a good sound absorption coefficient (noise reduction coefficient [NRC] value of 0.20-0.30). It also shows a high compressive Young's modulus of up to 150 kPa. Therefore, the newly developed fly ash aerogel is a potential material for thermal and acoustic insulation applications, along with lightweight composites in automotive and aerospace applications.
Journal of Environmental Chemical Engineering, 2020
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Journal of Environmental Chemical Engineering, 2020
Petroleum spills have been described as one of the leading aquatic disasters that has resulted in... more Petroleum spills have been described as one of the leading aquatic disasters that has resulted in the destruction and degradation of marine ecosystems worldwide, destroying the lives of thousands of organisms within a short period. Parts of the causes of this may be linked to waste products from plastics and rubber tires. This study focuses on fibers from rubber tires, and successfully produces rubber aerogels from them using glutaraldehyde and poly(vinyl alcohol) binders, followed by a freeze-drying process. Our recycled rubber aerogels are extremely pore (92.2-98.3 %) and ultra-low density (0.020−0.091 g/cm 3). After a methyltrimethoxysilane (MTMS) coating, rubber aerogels show their super-hydrophobic properties with a water contact angle up to 153°. The effects of rubber fiber and cross-linker contents on the rubber aerogel oil absorption efficiency are thoroughly investigated. Pseudo-first-order and pseudo-second-order kinetics are studied for the absorption of rubber aerogel and the result shows that the pseudo-second-order model could better predict oil absorption performance. A maximum rubber aerogel oil absorption of up to 25.0 g/g is estimated, approximately 1.7 and 2.8 times higher compared to commercial polypropylene mat and nonwoven polypropylene, respectively. Such a material can play an instrumental role towards recycling of car tires and paves the way for maximizing the recycling capacity of waste rubber tires globally. This will in turn reduce the global and environmental impact of waste pollution associated with untreated car tires.
Over twenty million tons of pineapples have been produced annually worldwide, but their waste is ... more Over twenty million tons of pineapples have been produced annually worldwide, but their waste is mostly discarded or burnt after harvesting. In this work, the high-value added aerogels from the pineapple leaf waste are developed for the first time by using polyvinyl alcohol (PVA) cross-linkers and a cost-effective freeze drying process. The pineapple fibre (PF) aerogels have highly porous structures with the porosities of 96.98-98.85%, ultra-low densities of 0.013-0.033 g/cm 3 , and hydrophobicity with water contact angles of approximately 140°, after a surface modification with methyltrimethoxysilane (MTMS). The effects of PF concentrations (0.5-2.0 wt. %) on oil and organic solvent adsorption are investigated comprehensively. Experimental results indicate that the hydrophobic PF aerogels can adsorb motor oil up to 37.9 g/g, approximately two times greater than commercial polypropylene and polyurethane sorbents. The pseudo-second order model can provide a good fit for the oild adsorption kinetics of the developed aerogels.
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Millions of tons of plastic are produced annually, but less than 10% are reported to be recycled.... more Millions of tons of plastic are produced annually, but less than 10% are reported to be recycled. This work sets out to transform environmental plastic (polyethylene terephthalate-PET) waste into aerogels for high-value engineering applications, primarily to enhance the monetary incentive in recycling plastics. Coating techniques, using silicone ceramic (SCC) and (3-aminopropyl)triethoxysilane (APS, or APTES) solutions, are successfully devised to enhance the thermal stability and CO 2 adsorption capability of rPET aerogel. The rPET/SCC aerogel exhibits improved thermal stability (up to 600°C), enhanced thermal insulation (thermal conductivity K avg = [31.8-34.9] mW/mÁK), hydrophobic characteristics (up to 144.7°i n contact angle) and enhanced rigidity (Young modulus E avg = [4.5-124.8] kPa), while maintaining an ultra-low density (q a = [14-62] g/cm 3) and a high porosity (U avg = [95.6-99.0]%). Moreover, the aminefunctionalised rPET aerogel achieves a CO 2 adsorption capacity of up to 0.44 mmol CO 2 /g, superior to several commercial physio-sorbents. These promising results obtained demonstrate that the rPET aerogel is a versatile material suitable for a wide variety of high-value engineering applications, including thermal insulation and direct CO 2 capture applications.
Exercising in a tropical climate with constant high temperatures and high humidity increases the ... more Exercising in a tropical climate with constant high temperatures and high humidity increases the risk of heatstroke for active people who frequently train outdoors. For these active persons, a cooling source of water nearby can be essential, and this is usually carried in canteen bottles. However, commercially available water canteen bottles have limited thermal insulation capability to keep the liquid content cooled for the required period. This work proposed an engineering solution to enhance the heat insulation performance of water canteen bottles, using recycled cellulose aerogels made from paper waste for the first time as an insulating layer. Recycled cellulose aerogels wrapped around the water canteen bottle provides excellent thermal insulation performance, while not adding significant weight to the bottle. The temperature of the ice slurry in the canteen bottle was measured periodically over four hours with a mercury thermometer. The effects of the static and dynamic condit...
� Recycled PET is converted into an aerogel by an advanced and cost-effective method. � The mater... more � Recycled PET is converted into an aerogel by an advanced and cost-effective method. � The material has high oil absorption capacities of 46-80 times of its weight. � Aerogel presents good absorption capacity with different pollutant organic solvents. � Oil absorption kinetics are investigated by pseudo-first and-second order models. � The rPET aerogels present a good elasticity with low elastic modulus.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2019
For the first time, recycled car tire fibers (RCTF) shredded from car tire waste are developed su... more For the first time, recycled car tire fibers (RCTF) shredded from car tire waste are developed successfully into a novel material, a rubber aerogel, using polyvinyl alcohol (PVA) and glutaraldehyde (GA) as crosslinkers through a cost-effective freeze-drying method. Its structure and main physical properties are investigated comprehensively for high-value applications, such as heat and sound insulation of buildings and oil spill spilling clean up. The rubber aerogel has ultra-low density (ρ a = 0.035-0.145 g/cm 3) and high porosity (Φ avg = 84.31-96.20 %). With a simple but effective coating method with methoxytrimethylsilane (MTMS), both the interior and exterior of the whole rubber aerogel surface can be well coated, and the coated aerogel exhibits a super-hydrophobicity with a water contact angle of up to 134.4°. The rubber aerogel exhibits excellent heat insulation properties (K avg = 0.035-0.047 W/m.K), very good thermal stability up to 500°C, and significantly-enhanced rigidity up to a Young modulus of E avg = 458.12 kPa, much larger than that of commercial Styrofoam. The rubber aerogel shows very good durability as it springs back to its original shape after compression tests. The rubber aerogel has a noise reduction coefficient (NRC) of 0.41 and performs approximately 10% better than commercial sound foam absorber at 2000-3000 Hz. The maximum oil absorbtion capacity of the rubber aerogel in this work is 19.3 g/g, very competitive to commercial sorbents. The fabrication method can also be scaled up for several other industrial applications, not limited to sound, heat and sorbent applications.
This work presents for the first time, a simple, practical and scalable approach to fabricating r... more This work presents for the first time, a simple, practical and scalable approach to fabricating recycled polyethylene terephthalate (rPET) aerogels for thermal and acoustic insulation applications. The rPET aerogels were successfully developed from recycled PET fibers and polyvinyl alcohol (PVA) and glutaraldehyde (GA) cross-linkers using a freeze-drying process. The effects of various PET fiber concentrations (0.5, 1.0 and 2.0 by wt.%), fiber deniers (3D, 7D and 15D) and fiber lengths (32 mm and 64 mm) on the rPET aerogel structures and multi-properties were comprehensively investigated. The developed rPET aerogels showed a highly porous network structure (98.3-99.5%), ultra-low densities (0.007-0.026 g/cm 3), hydrophobicity with water contact angles of 120.7-149.8 • , and high elasticity with low compressive Young's modulus (1.16-2.87 kPa). They exhibited superior thermal insulation capability with low thermal conductivities of 0.035-0.038 W/m.K, which are highly competitive with recycled cellulose and silica-cellulose aerogels and better than mineral wool and polystyrene. The acoustic absorption results were also found to outperform a commercial acoustic foam absorber across a range of frequencies.
With the aim of introduction a new inexpensive co-adsorbent to improve solar cell performance, th... more With the aim of introduction a new inexpensive co-adsorbent to improve solar cell performance, the influence of nicotinic acid (NTA) used as a co-adsorbent in dye-sensitized solar cells (DSCs) was investigated. The findings showed that low concentrations of NTA (<10 mM) increased the N719 ruthenium dye loading on the TiO 2 electrode surface by 10-12%, whereas higher concentrations of NTA lowered the dye loading. The adsorption of NTA onto the TiO 2 electrode surface was studied by attenuated total reflectance Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, and the blocking effect of NTA toward electron transfer between the electrode and 1,4-dicyanonaphthalene (redox couple electrolyte probe) was investigated by cyclic voltammetry. Subsequently, the performance of NTA in functional DSCs was evaluated by current-voltage (J-V) DSC characterization and compared with that of DSCs fabricated with two well-established co-adsorbents i.e., chenodeoxycholic acid (CDA) and octadecylphosphonic acid (OPA). The findings showed that under optimized co-adsorbent concentration (1 mM NTA, 0.03 mM CDA, 0.015 mM OPA), the efficiency of the corresponding solar cells increased to the same extent. Specifically, the use of NTA at optimum concentration improved the efficiency of the resulting DSC from 3.14 to 5.02%.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2016
Silica-cellulose aerogels were successfully developed from recycled cellulose fibres and methoxyt... more Silica-cellulose aerogels were successfully developed from recycled cellulose fibres and methoxytrimethylsilane (MTMS) silica precursor for the first time. The silica-cellulose aerogels showed the super-hydrophobicity with an average water contact angle of 151 o. The silica-cellulose aerogels developed in this work showed a promising potential for thermal and acoustic insulation applications. This work provides a facile approach to fabricate cost-effective silica-cellulose aerogels with industrial dimensions.
Although α-diazo-β-ketoesters are synthetically versatile intermediates, methodology for introduc... more Although α-diazo-β-ketoesters are synthetically versatile intermediates, methodology for introducing this functionality into complex molecules is still limited, most frequently involving a carboxylic acid precursor, which is then activated and transformed into a β-ketoester, with the diazo group being subsequently added with a diazo transfer reagent. While introducing this highly functional moiety in a convergent one step process would be ideal, such an objective is limited by the relatively few studies which address functionalization of the α-diazo-β-ketoester at the γposition. In the present investigation, we evaluate strategies, both new and established, for functionalizing α-diazo-β-ketoesters, particularly with regard to generating compounds prospectively useful in the synthesis of C1-substituted carbapenems. We report the first δaldehydo-α-diazo-β-ketoester as well as a method for its oxidation to the corresponding methyl ester, and the formation of a new substituted pyrazole under basic conditions.
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