Saifuddin Nomanbhay | Universiti Tenaga Nasional (original) (raw)

Papers by Saifuddin Nomanbhay

Energies

Catalytic reactions in producing biofuels often face issues such as low product yield, low select... more Catalytic reactions in producing biofuels often face issues such as low product yield, low selectivity to preferred products and serious environmental issues which leads to the exploration of green technologies. Microwave technology is one of the green technologies that is widely applied in the field such as medical, food, signal processing or navigation, and has been reviewed for its potential in the catalytic reactions for biofuel production. With the application of microwave technology, its unique heating mechanism consists of magnetic field energy and electric field energy that enables the selective heating of materials, allowing rapid reaction and enhancement of catalytic performance of catalysts. In general, this review has discussed on the fundamentals and mechanisms of microwave technology with an in-depth discussion on the application of microwave-absorbing catalysts for biofuel production, especially in ammonia synthesis, bio-oil and 5-HMF production as well as methanation...

In Malaysia, the palm oil industry rapid development has increased the environmental problems due... more In Malaysia, the palm oil industry rapid development has increased the environmental problems due to the discharge of large amounts of palm oil mill effluent (POME) into the water sources. However, POME consists of a high level of phenolic compounds, a potential source of natural antioxidants. An enhancement of the recovery process of these phenolic compounds from POME is required to increase the opportunity of this bioburden transformation into health and wellness applications. This study describes an improvement in the extraction efficiency of phenolic compounds through the combination of microwave-assisted extraction (MAE) and enzymatic hydrolysis. The latter proceeds in presence of Ragi tapai as it is readily available at any local market in Malaysia. Conventional maceration is performed aiming a comparison. The results show that 50 % ethanol is the best extracting solvent among those used. Besides, MAE provides an increase of the phenolic compounds extraction yield by 15.8 % at...

Sustainability, 2021

The rapid spread of coronavirus disease 2019 (COVID-19) in early 2020 prompted a global lockdown ... more The rapid spread of coronavirus disease 2019 (COVID-19) in early 2020 prompted a global lockdown from March to July 2020. Due to strict lockdown measures, many countries experienced economic downturns, negatively affecting many industries including energy, manufacturing, agriculture, finance, healthcare, food, education, tourism, and sports. Despite this, the COVID-19 pandemic provided a rare opportunity to observe the impacts of worldwide lockdown on global carbon dioxide (CO2) emissions and climate change. Being the main greenhouse gas responsible for rising global surface temperature, CO2 is released to the atmosphere primarily by burning fossil fuels. Compared to 2019, CO2 emissions for the world and Malaysia decreased significantly by 4.02% (−1365.83 MtCO2) and 9.7% (−225.97 MtCO2) in 2020. However, this is insufficient to cause long-term impacts on global CO2 levels and climate change. Therefore, in this review, we explored the effects of worldwide lockdown on global CO2 level...

Processes, 2021

In this study, the response surface methodology (RSM) optimization technique was employed for inv... more In this study, the response surface methodology (RSM) optimization technique was employed for investigating the impact of hydroxy gas (HHO) enriched diesel on performance, acoustics, smoke and exhaust gas emissions of the compression ignition (CI) engine. The engine was operated within the HHO flow rate range of 0–10 L/min and engine loads of 15%, 30%, 45%, 60% and 75%. The results disclosed that HHO concentration and engine load had a substantial influence on the response variables. Analysis of variance (ANOVA) results of developed quadratic models indicated the appropriate fit for all models. Moreover, the optimization of the user-defined historical design of an experiment identified an optimum HHO flow rate of 8 L/min and 41% engine load, with composite desirability of 0.733. The responses corresponding to optimal study factors were 25.44%, 0.315 kg/kWh, 117.73 ppm, 140.87 ppm, 99.37 dB, and 1.97% for brake thermal efficiency (BTE), brake specific fuel consumption (BSFC), CO, HC,...

Melaleuca cajuputi Powell or known as cajuput tree is a native tree to Peninsular Malaysia where... more Melaleuca cajuputi Powell or known as cajuput tree is a native tree to Peninsular Malaysia where it easily grows near to the swampy forest. The essential oil extracted from its leaf have many benefits due to its chemical compound. One of its benefits is to work as an insect repellent. Hence, the main objective of this study is to evaluate the biological efficacy of the M. cajuputi Powell based product against the mosquito. The essential oil extracted from the fresh leaves through steam distillation was formulated into two products which are Mosquito repellent roll-on and mosquito repellent diffuser. Mosquito repellent roll on undergo skin repellent analysis using Bioassay Method for Mosquito Repellent on Human Skin followed Malaysian Standard Procedure while mosquito repellent diffuser was analyzed for spatial repellent using choice test method developed by Vector Control Research Unit (VCRU). Both samples with 5% concentration were tested against the dengue vector (Aedesae...

Bioengineering

The environmental impacts and high long-term costs of poor waste disposal have pushed the industr... more The environmental impacts and high long-term costs of poor waste disposal have pushed the industry to realize the potential of turning this problem into an economic and sustainable initiative. Anaerobic digestion and the production of biogas can provide an efficient means of meeting several objectives concerning energy, environmental, and waste management policy. Biogas contains methane (60%) and carbon dioxide (40%) as its principal constituent. Excluding methane, other gasses contained in biogas are considered as contaminants. Removal of these impurities, especially carbon dioxide, will increase the biogas quality for further use. Integrating biological processes into the bio-refinery that effectively consume carbon dioxide will become increasingly important. Such process integration could significantly improve the sustainability of the overall bio-refinery process. The biogas upgrading by utilization of carbon dioxide rather than removal of it is a suitable strategy in this direc...

Bioengineering

The conversion of biomass into chemicals and biofuels is an active research area as trends move t... more The conversion of biomass into chemicals and biofuels is an active research area as trends move to replace fossil fuels with renewable resources due to society’s increased concern towards sustainability. In this context, microwave processing has emerged as a tool in organic synthesis and plays an important role in developing a more sustainable world. Integration of processing methods with microwave irradiation has resulted in a great reduction in the time required for many processes, while the reaction efficiencies have been increased markedly. Microwave processing produces a higher yield with a cleaner profile in comparison to other methods. The microwave processing is reported to be a better heating method than the conventional methods due to its unique thermal and non-thermal effects. This paper provides an insight into the theoretical aspects of microwave irradiation practices and highlights the importance of microwave processing. The potential of the microwave technology to acc...

Energies

Hybrid systems have gained significant attention among researchers and scientists worldwide due t... more Hybrid systems have gained significant attention among researchers and scientists worldwide due to their ability to integrate solar cells and supercapacitors. Subsequently, this has led to rising demands for green energy, miniaturization and mini-electronic wearable devices. These hybrid devices will lead to sustainable energy becoming viable and fossil-fuel-based sources of energy gradually being replaced. A solar photovoltaic (SPV) system is an electronic device that mainly functions to convert photon energy to electrical energy using a solar power source. It has been widely used in developed countries given that they have advanced photovoltaic (PV) technology that reduces dependence on fossil fuels for energy generation. Furthermore, a supercapacitor is an alternative solution for replacing heavy batteries and it is a system with a prominent high power density and a long life cycle. Its unique properties of high capacitance with low voltage limits lead to this highly in-demand ma...

Indian Journal of Microbiology

Frontiers in Energy Research

Renewable diesel as a potential sustainable energy source in future requires catalysts to convert... more Renewable diesel as a potential sustainable energy source in future requires catalysts to convert the feedstocks into end products. Among various type of catalysts, bimetallic catalysts are widely applied in the renewable diesel production due to their unique catalytic properties and enhanced catalytic activities, which differ from their parent monometallic catalysts. This mini review comprised of the brief introduction on technologies in producing renewable diesel and aims to discuss the underneath knowledge of synergistic interactions in bimetallic catalysts that synthesized through various techniques. The novelty of this review reveals the recent development of renewable diesel production, highlighting the mechanisms of bimetallic catalysts in the enhancement of the catalytic activity, and exploring their possibilities as practical solution in industrial production.

Energies

In this study, coconut oils have been transesterified with ethanol using microwave technology. Th... more In this study, coconut oils have been transesterified with ethanol using microwave technology. The product obtained (biodiesel and FAEE) was then fractional distillated under vacuum to collect bio-kerosene or bio-jet fuel, which is a renewable fuel to operate a gas turbine engine. This process was modeled using RSM and ANN for optimization purposes. The developed models were proved to be reliable and accurate through different statistical tests and the results showed that ANN modeling was better than RSM. Based on the study, the optimum bio-jet fuel production yield of 74.45 wt% could be achieved with an ethanol–oil molar ratio of 9.25:1 under microwave irradiation with a power of 163.69 W for 12.66 min. This predicted value was obtained from the ANN model that has been optimized with ACO. Besides that, the sensitivity analysis indicated that microwave power offers a dominant impact on the results, followed by the reaction time and lastly ethanol–oil molar ratio. The properties of t...

Journal of Cleaner Production

Fuel

Abstract The excessive global emission of greenhouse gases (mainly carbon dioxide, CO2 and methan... more Abstract The excessive global emission of greenhouse gases (mainly carbon dioxide, CO2 and methane, CH4), especially due to the burning of fossil fuel for energy and power generation, is the main cause to the air pollution and greenhouse effect. This has eventually brought many issues, such as climate change and global warming, that will affect the standard life of human beings. Many strategies have been proposed to further reduce the excessive emission of greenhouse gases, including CO2 and CH4 utilization. This method not only reduce the CO2 concentration in the atmosphere, but also producing renewable energy (syngas) at the same time. Hence, CO2 and CH4 utilization is also a promising approach to assist in overcoming the energy crisis due to the increasing population in time. Basically, the utilization of CO2 and CH4 system can be categorized into four: (i) electrochemical reduction, (ii) advanced catalyst system, (iii) photocatalytic reduction, and (iv) plasma technology. In this review paper, the mechanism implemented on the four abovementioned categories and their respective limitations are presented. Besides, future recommendations to optimize the greenhouse gases utilization system for up-scaling purpose is also highlighted.

Chemosphere

Recently, the production of renewable biogas such as biohydrogen and biomethane from wastewaters ... more Recently, the production of renewable biogas such as biohydrogen and biomethane from wastewaters through anaerobic fermentation has gained worldwide attention. In the present study, a mobile bioenergy generation station had been constructed based on a high-efficiency hydrogenesis & methanogenesis technology (HyMeTek) developed by Feng Chia University, Taiwan. The substrate was a beverage wastewater having chemical oxygen demand (COD) concentration of 1200 mg/L. This bioenergy station had a feedstock tank (3.8 m3), a nutrient tank (0.8 m3), an acidogenesis tank (AT, 2 m3), two methanogenesis tanks (MT, 4 m3 for each), a membrane bioreactor and a control room. Biogas production rate, methane concentration, COD removal efficiencies, energy efficiency and economical interest of the plant were assessed. The peak total methane production rates for AT (at hydraulic retention time, HRT, 4 h) and MT (at HRT 8 h) were 430 and 7 mL/L·d, respectively. A strategy of shortening HRT was a promising method to enhance biogas quality and energy efficiency. This mobile bioenergy system has commercial potential because it could bring good economic benefit of initial rate of return (58.84%) and payback time (2.68 y).

Processes

Carbon dioxide is the most influential gas in greenhouse gasses and its amount in the atmosphere ... more Carbon dioxide is the most influential gas in greenhouse gasses and its amount in the atmosphere reached 412 µmol/mol in August 2020, which increased rapidly, by 48%, from preindustrial levels. A brand-new chemical industry, namely organic chemistry and catalysis science, must be developed with carbon dioxide (CO2) as the source of carbon. Nowadays, many techniques are available for controlling and removing carbon dioxide in different chemical processes. Since the utilization of CO2 as feedstock for a chemical commodity is of relevance today, this study will focus on how to increase CO2 solubility in culture media used for growing microbes. In this work, the CO2 solubility in a different medium was investigated. Sodium hydroxide (NaOH) and monoethanolamine (MEA) were added to the culture media (3.0 g/L dipotassium phosphate (K2HPO4), 0.2 g/L magnesium chloride (MgCl2), 0.2 g/L calcium chloride (CaCl2), and 1.0 g/L sodium chloride (NaCl)) for growing microbes in order to observe the ...

Energies

As a promising alternative renewable liquid fuel, biodiesel production has increased and eventual... more As a promising alternative renewable liquid fuel, biodiesel production has increased and eventually led to an increase in the production of its by-product, crude glycerol. The vast generation of glycerol has surpassed the market demand. Hence, the crude glycerol produced should be utilized effectively to increase the viability of biodiesel production. One of them is through crude glycerol upgrading, which is not economical. A good deal of attention has been dedicated to research for alternative material and chemicals derived from sustainable biomass resources. It will be more valuable if the crude glycerol is converted into glycerol derivatives, and so, increase the economic possibility of the biodiesel production. Studies showed that glycerol carbonate plays an important role, as a building block, in synthesizing the glycerol oligomers at milder conditions under microwave irradiation. This review presents a brief outline of the physio-chemical, thermodynamic, toxicological, product...

Energy

Abstract The society’s concern has moved toward sustainability nowadays and hence, the conversion... more Abstract The society’s concern has moved toward sustainability nowadays and hence, the conversion of biomass into biofuels, through pyrolysis process, is one of the current research trends. Green processing technologies, like microwave heating, has been suggested to replace the conventional heating for biomass conversion as it provides energy-efficient heating and reduces time consumption. In this work, COMSOL Multiphysics software was used to study the effects of the waveguide position (bottom-fed vs side-fed) and unit (single-fed vs double-fed) on the electromagnetic field and heat distribution profile within the sample. Based on the results, the double-fed microwave can achieve higher maximum temperature (462 °C) at the same simulation time, followed by the single bottom-fed reactor (404 °C). An extension to the investigated work with more than two waveguides has shown that it will neither improve the electric field distribution nor increase the maximum temperature. This work concludes that both the position and unit of the waveguide are highly influential factors in determining the quality and speed of the biomass heating process. The double-fed microwave is the most suitable design to accelerate the pyrolysis process. The assumption of this simulation study is further validated as there is only ∼5% difference between simulations and experiments.

Green Chemistry Letters and Reviews

Energies

The potential of Caulerpa lentillifera, Gracilaria coronopifolia and Chaetomorpha linum, as bioma... more The potential of Caulerpa lentillifera, Gracilaria coronopifolia and Chaetomorpha linum, as biomass feedstock was investigated in this study. It was concluded that seaweed is more suitable for bio-based products synthesis, i.e., bioplastic and bio-lubricants, instead of biofuels due to its relatively low calorific value (~12 MJ/kg). Since seaweed has high moisture content (~80%), hydrothermal liquefaction is recommended, and its efficiency can be further enhanced through microwave technology. Besides, it is found that the thermal degradation of seaweed was best described with the reaction order of 1. The kinetic results also indicated that seaweed consists of lower activation energy (<30 kJ/mol) in comparison with terrestrial biomass (50–170 kJ/mol). Hence, seaweed has a high potential to be used as biomass feedstock, particularly Chaetomorpha linum, as it has no conflict with other interests. Lastly, acetic-acid pre-treatment was suggested to be an optional process in order to i...

Energies

Catalytic reactions in producing biofuels often face issues such as low product yield, low select... more Catalytic reactions in producing biofuels often face issues such as low product yield, low selectivity to preferred products and serious environmental issues which leads to the exploration of green technologies. Microwave technology is one of the green technologies that is widely applied in the field such as medical, food, signal processing or navigation, and has been reviewed for its potential in the catalytic reactions for biofuel production. With the application of microwave technology, its unique heating mechanism consists of magnetic field energy and electric field energy that enables the selective heating of materials, allowing rapid reaction and enhancement of catalytic performance of catalysts. In general, this review has discussed on the fundamentals and mechanisms of microwave technology with an in-depth discussion on the application of microwave-absorbing catalysts for biofuel production, especially in ammonia synthesis, bio-oil and 5-HMF production as well as methanation...

In Malaysia, the palm oil industry rapid development has increased the environmental problems due... more In Malaysia, the palm oil industry rapid development has increased the environmental problems due to the discharge of large amounts of palm oil mill effluent (POME) into the water sources. However, POME consists of a high level of phenolic compounds, a potential source of natural antioxidants. An enhancement of the recovery process of these phenolic compounds from POME is required to increase the opportunity of this bioburden transformation into health and wellness applications. This study describes an improvement in the extraction efficiency of phenolic compounds through the combination of microwave-assisted extraction (MAE) and enzymatic hydrolysis. The latter proceeds in presence of Ragi tapai as it is readily available at any local market in Malaysia. Conventional maceration is performed aiming a comparison. The results show that 50 % ethanol is the best extracting solvent among those used. Besides, MAE provides an increase of the phenolic compounds extraction yield by 15.8 % at...

Sustainability, 2021

The rapid spread of coronavirus disease 2019 (COVID-19) in early 2020 prompted a global lockdown ... more The rapid spread of coronavirus disease 2019 (COVID-19) in early 2020 prompted a global lockdown from March to July 2020. Due to strict lockdown measures, many countries experienced economic downturns, negatively affecting many industries including energy, manufacturing, agriculture, finance, healthcare, food, education, tourism, and sports. Despite this, the COVID-19 pandemic provided a rare opportunity to observe the impacts of worldwide lockdown on global carbon dioxide (CO2) emissions and climate change. Being the main greenhouse gas responsible for rising global surface temperature, CO2 is released to the atmosphere primarily by burning fossil fuels. Compared to 2019, CO2 emissions for the world and Malaysia decreased significantly by 4.02% (−1365.83 MtCO2) and 9.7% (−225.97 MtCO2) in 2020. However, this is insufficient to cause long-term impacts on global CO2 levels and climate change. Therefore, in this review, we explored the effects of worldwide lockdown on global CO2 level...

Processes, 2021

In this study, the response surface methodology (RSM) optimization technique was employed for inv... more In this study, the response surface methodology (RSM) optimization technique was employed for investigating the impact of hydroxy gas (HHO) enriched diesel on performance, acoustics, smoke and exhaust gas emissions of the compression ignition (CI) engine. The engine was operated within the HHO flow rate range of 0–10 L/min and engine loads of 15%, 30%, 45%, 60% and 75%. The results disclosed that HHO concentration and engine load had a substantial influence on the response variables. Analysis of variance (ANOVA) results of developed quadratic models indicated the appropriate fit for all models. Moreover, the optimization of the user-defined historical design of an experiment identified an optimum HHO flow rate of 8 L/min and 41% engine load, with composite desirability of 0.733. The responses corresponding to optimal study factors were 25.44%, 0.315 kg/kWh, 117.73 ppm, 140.87 ppm, 99.37 dB, and 1.97% for brake thermal efficiency (BTE), brake specific fuel consumption (BSFC), CO, HC,...

Melaleuca cajuputi Powell or known as cajuput tree is a native tree to Peninsular Malaysia where... more Melaleuca cajuputi Powell or known as cajuput tree is a native tree to Peninsular Malaysia where it easily grows near to the swampy forest. The essential oil extracted from its leaf have many benefits due to its chemical compound. One of its benefits is to work as an insect repellent. Hence, the main objective of this study is to evaluate the biological efficacy of the M. cajuputi Powell based product against the mosquito. The essential oil extracted from the fresh leaves through steam distillation was formulated into two products which are Mosquito repellent roll-on and mosquito repellent diffuser. Mosquito repellent roll on undergo skin repellent analysis using Bioassay Method for Mosquito Repellent on Human Skin followed Malaysian Standard Procedure while mosquito repellent diffuser was analyzed for spatial repellent using choice test method developed by Vector Control Research Unit (VCRU). Both samples with 5% concentration were tested against the dengue vector (Aedesae...

Bioengineering

The environmental impacts and high long-term costs of poor waste disposal have pushed the industr... more The environmental impacts and high long-term costs of poor waste disposal have pushed the industry to realize the potential of turning this problem into an economic and sustainable initiative. Anaerobic digestion and the production of biogas can provide an efficient means of meeting several objectives concerning energy, environmental, and waste management policy. Biogas contains methane (60%) and carbon dioxide (40%) as its principal constituent. Excluding methane, other gasses contained in biogas are considered as contaminants. Removal of these impurities, especially carbon dioxide, will increase the biogas quality for further use. Integrating biological processes into the bio-refinery that effectively consume carbon dioxide will become increasingly important. Such process integration could significantly improve the sustainability of the overall bio-refinery process. The biogas upgrading by utilization of carbon dioxide rather than removal of it is a suitable strategy in this direc...

Bioengineering

The conversion of biomass into chemicals and biofuels is an active research area as trends move t... more The conversion of biomass into chemicals and biofuels is an active research area as trends move to replace fossil fuels with renewable resources due to society’s increased concern towards sustainability. In this context, microwave processing has emerged as a tool in organic synthesis and plays an important role in developing a more sustainable world. Integration of processing methods with microwave irradiation has resulted in a great reduction in the time required for many processes, while the reaction efficiencies have been increased markedly. Microwave processing produces a higher yield with a cleaner profile in comparison to other methods. The microwave processing is reported to be a better heating method than the conventional methods due to its unique thermal and non-thermal effects. This paper provides an insight into the theoretical aspects of microwave irradiation practices and highlights the importance of microwave processing. The potential of the microwave technology to acc...

Energies

Hybrid systems have gained significant attention among researchers and scientists worldwide due t... more Hybrid systems have gained significant attention among researchers and scientists worldwide due to their ability to integrate solar cells and supercapacitors. Subsequently, this has led to rising demands for green energy, miniaturization and mini-electronic wearable devices. These hybrid devices will lead to sustainable energy becoming viable and fossil-fuel-based sources of energy gradually being replaced. A solar photovoltaic (SPV) system is an electronic device that mainly functions to convert photon energy to electrical energy using a solar power source. It has been widely used in developed countries given that they have advanced photovoltaic (PV) technology that reduces dependence on fossil fuels for energy generation. Furthermore, a supercapacitor is an alternative solution for replacing heavy batteries and it is a system with a prominent high power density and a long life cycle. Its unique properties of high capacitance with low voltage limits lead to this highly in-demand ma...

Indian Journal of Microbiology

Frontiers in Energy Research

Renewable diesel as a potential sustainable energy source in future requires catalysts to convert... more Renewable diesel as a potential sustainable energy source in future requires catalysts to convert the feedstocks into end products. Among various type of catalysts, bimetallic catalysts are widely applied in the renewable diesel production due to their unique catalytic properties and enhanced catalytic activities, which differ from their parent monometallic catalysts. This mini review comprised of the brief introduction on technologies in producing renewable diesel and aims to discuss the underneath knowledge of synergistic interactions in bimetallic catalysts that synthesized through various techniques. The novelty of this review reveals the recent development of renewable diesel production, highlighting the mechanisms of bimetallic catalysts in the enhancement of the catalytic activity, and exploring their possibilities as practical solution in industrial production.

Energies

In this study, coconut oils have been transesterified with ethanol using microwave technology. Th... more In this study, coconut oils have been transesterified with ethanol using microwave technology. The product obtained (biodiesel and FAEE) was then fractional distillated under vacuum to collect bio-kerosene or bio-jet fuel, which is a renewable fuel to operate a gas turbine engine. This process was modeled using RSM and ANN for optimization purposes. The developed models were proved to be reliable and accurate through different statistical tests and the results showed that ANN modeling was better than RSM. Based on the study, the optimum bio-jet fuel production yield of 74.45 wt% could be achieved with an ethanol–oil molar ratio of 9.25:1 under microwave irradiation with a power of 163.69 W for 12.66 min. This predicted value was obtained from the ANN model that has been optimized with ACO. Besides that, the sensitivity analysis indicated that microwave power offers a dominant impact on the results, followed by the reaction time and lastly ethanol–oil molar ratio. The properties of t...

Journal of Cleaner Production

Fuel

Abstract The excessive global emission of greenhouse gases (mainly carbon dioxide, CO2 and methan... more Abstract The excessive global emission of greenhouse gases (mainly carbon dioxide, CO2 and methane, CH4), especially due to the burning of fossil fuel for energy and power generation, is the main cause to the air pollution and greenhouse effect. This has eventually brought many issues, such as climate change and global warming, that will affect the standard life of human beings. Many strategies have been proposed to further reduce the excessive emission of greenhouse gases, including CO2 and CH4 utilization. This method not only reduce the CO2 concentration in the atmosphere, but also producing renewable energy (syngas) at the same time. Hence, CO2 and CH4 utilization is also a promising approach to assist in overcoming the energy crisis due to the increasing population in time. Basically, the utilization of CO2 and CH4 system can be categorized into four: (i) electrochemical reduction, (ii) advanced catalyst system, (iii) photocatalytic reduction, and (iv) plasma technology. In this review paper, the mechanism implemented on the four abovementioned categories and their respective limitations are presented. Besides, future recommendations to optimize the greenhouse gases utilization system for up-scaling purpose is also highlighted.

Chemosphere

Recently, the production of renewable biogas such as biohydrogen and biomethane from wastewaters ... more Recently, the production of renewable biogas such as biohydrogen and biomethane from wastewaters through anaerobic fermentation has gained worldwide attention. In the present study, a mobile bioenergy generation station had been constructed based on a high-efficiency hydrogenesis & methanogenesis technology (HyMeTek) developed by Feng Chia University, Taiwan. The substrate was a beverage wastewater having chemical oxygen demand (COD) concentration of 1200 mg/L. This bioenergy station had a feedstock tank (3.8 m3), a nutrient tank (0.8 m3), an acidogenesis tank (AT, 2 m3), two methanogenesis tanks (MT, 4 m3 for each), a membrane bioreactor and a control room. Biogas production rate, methane concentration, COD removal efficiencies, energy efficiency and economical interest of the plant were assessed. The peak total methane production rates for AT (at hydraulic retention time, HRT, 4 h) and MT (at HRT 8 h) were 430 and 7 mL/L·d, respectively. A strategy of shortening HRT was a promising method to enhance biogas quality and energy efficiency. This mobile bioenergy system has commercial potential because it could bring good economic benefit of initial rate of return (58.84%) and payback time (2.68 y).

Processes

Carbon dioxide is the most influential gas in greenhouse gasses and its amount in the atmosphere ... more Carbon dioxide is the most influential gas in greenhouse gasses and its amount in the atmosphere reached 412 µmol/mol in August 2020, which increased rapidly, by 48%, from preindustrial levels. A brand-new chemical industry, namely organic chemistry and catalysis science, must be developed with carbon dioxide (CO2) as the source of carbon. Nowadays, many techniques are available for controlling and removing carbon dioxide in different chemical processes. Since the utilization of CO2 as feedstock for a chemical commodity is of relevance today, this study will focus on how to increase CO2 solubility in culture media used for growing microbes. In this work, the CO2 solubility in a different medium was investigated. Sodium hydroxide (NaOH) and monoethanolamine (MEA) were added to the culture media (3.0 g/L dipotassium phosphate (K2HPO4), 0.2 g/L magnesium chloride (MgCl2), 0.2 g/L calcium chloride (CaCl2), and 1.0 g/L sodium chloride (NaCl)) for growing microbes in order to observe the ...

Energies

As a promising alternative renewable liquid fuel, biodiesel production has increased and eventual... more As a promising alternative renewable liquid fuel, biodiesel production has increased and eventually led to an increase in the production of its by-product, crude glycerol. The vast generation of glycerol has surpassed the market demand. Hence, the crude glycerol produced should be utilized effectively to increase the viability of biodiesel production. One of them is through crude glycerol upgrading, which is not economical. A good deal of attention has been dedicated to research for alternative material and chemicals derived from sustainable biomass resources. It will be more valuable if the crude glycerol is converted into glycerol derivatives, and so, increase the economic possibility of the biodiesel production. Studies showed that glycerol carbonate plays an important role, as a building block, in synthesizing the glycerol oligomers at milder conditions under microwave irradiation. This review presents a brief outline of the physio-chemical, thermodynamic, toxicological, product...

Energy

Abstract The society’s concern has moved toward sustainability nowadays and hence, the conversion... more Abstract The society’s concern has moved toward sustainability nowadays and hence, the conversion of biomass into biofuels, through pyrolysis process, is one of the current research trends. Green processing technologies, like microwave heating, has been suggested to replace the conventional heating for biomass conversion as it provides energy-efficient heating and reduces time consumption. In this work, COMSOL Multiphysics software was used to study the effects of the waveguide position (bottom-fed vs side-fed) and unit (single-fed vs double-fed) on the electromagnetic field and heat distribution profile within the sample. Based on the results, the double-fed microwave can achieve higher maximum temperature (462 °C) at the same simulation time, followed by the single bottom-fed reactor (404 °C). An extension to the investigated work with more than two waveguides has shown that it will neither improve the electric field distribution nor increase the maximum temperature. This work concludes that both the position and unit of the waveguide are highly influential factors in determining the quality and speed of the biomass heating process. The double-fed microwave is the most suitable design to accelerate the pyrolysis process. The assumption of this simulation study is further validated as there is only ∼5% difference between simulations and experiments.

Green Chemistry Letters and Reviews

Energies

The potential of Caulerpa lentillifera, Gracilaria coronopifolia and Chaetomorpha linum, as bioma... more The potential of Caulerpa lentillifera, Gracilaria coronopifolia and Chaetomorpha linum, as biomass feedstock was investigated in this study. It was concluded that seaweed is more suitable for bio-based products synthesis, i.e., bioplastic and bio-lubricants, instead of biofuels due to its relatively low calorific value (~12 MJ/kg). Since seaweed has high moisture content (~80%), hydrothermal liquefaction is recommended, and its efficiency can be further enhanced through microwave technology. Besides, it is found that the thermal degradation of seaweed was best described with the reaction order of 1. The kinetic results also indicated that seaweed consists of lower activation energy (<30 kJ/mol) in comparison with terrestrial biomass (50–170 kJ/mol). Hence, seaweed has a high potential to be used as biomass feedstock, particularly Chaetomorpha linum, as it has no conflict with other interests. Lastly, acetic-acid pre-treatment was suggested to be an optional process in order to i...