2023, Vol. 8, No. 4
Display Method:
2023, 8(4): 319-332.
doi: 10.1016/j.jobab.2023.06.002
Abstract:
Hydrogen as a clean energy carrier has attracted great interests world-wide for substitution of fossil fuels and for abatement of the climate change concerns. However, green hydrogen from renewable resources is less than 0.1% at present in the world hydrogen production and this is largely from water electrolysis which is beneficial only when renewable electricity is used. Hydrogen production from diverse renewable resources is desirable. This review presents recent advances in hydrogen production from woody biomass through biomass steam gasification, producer gas processing and H2/CO2 separation. The producer gas processing includes steam-methane reforming (SMR) and water-gas shift (WGS) reactions to convert CH4 and CO in the producer gas to H2 and CO2. The H2 storage discussed using liquid carrier through hydrogenation is also discussed. The CO2 capture prior to the SMR is investigated to enhance H2 yield in the SMR and the WGS reactions.
Hydrogen as a clean energy carrier has attracted great interests world-wide for substitution of fossil fuels and for abatement of the climate change concerns. However, green hydrogen from renewable resources is less than 0.1% at present in the world hydrogen production and this is largely from water electrolysis which is beneficial only when renewable electricity is used. Hydrogen production from diverse renewable resources is desirable. This review presents recent advances in hydrogen production from woody biomass through biomass steam gasification, producer gas processing and H2/CO2 separation. The producer gas processing includes steam-methane reforming (SMR) and water-gas shift (WGS) reactions to convert CH4 and CO in the producer gas to H2 and CO2. The H2 storage discussed using liquid carrier through hydrogenation is also discussed. The CO2 capture prior to the SMR is investigated to enhance H2 yield in the SMR and the WGS reactions.
2023, 8(4): 333-360.
doi: 10.1016/j.jobab.2023.09.005
Abstract:
Biomass solid fuel (BSF) has emerged as a promising renewable energy source, but its morphological and microstructural properties are crucial in determining their physical, mechanical, and chemical characteristics. This paper provides an overview of recent research on BSF. The focus is on biomass sources, BSF processing methods, and morphological and microstructural properties, with a special emphasis on energy-related studies. Specific inclusion and exclusion criteria were established for the study to ensure relevance. The inclusion criteria encompassed studies about BSFs and studies investigating the influence of biomass sources and processing methods on the morphological and microstructural properties of solid fuels within the past five years. Various technologies for converting biomass into usable energy were discussed, including gasification, torrefaction, carbonization, hydrothermal carbonization (HTC), and pyrolysis. Each has advantages and disadvantages in energy performance, techno-economics, and climate impact. Gasification is efficient but requires high investment. Pyrolysis produces bio-oil, char, and gases based on feedstock availability. Carbonization generates low-cost biochar for solid fuels and carbon sequestration applications. Torrefaction increases energy density for co-firing with coal. HTC processes wet biomass efficiently with lower energy input. Thermal treatment affects BSF durability and strength, often leading to less durability due to voids and gaps between particles. Hydrothermal carbonization alters surface morphology, creating cavities, pores, and distinctive shapes. Slow pyrolysis generates biochar with better morphological properties, while fast pyrolysis yields biochar with lower porosity and surface area. Wood constitutes 67% of the biomass sources utilized for bioenergy generation, followed by wood residues (5%), agro-residues (4%), municipal solid wastes (3%), energy crops (3%), livestock wastes (3%), and forest residues (1%). Each source has advantages and drawbacks, such as availability, cost, environmental impact, and suitability for specific regions and energy requirements. This review is valuable for energy professionals, researchers, and policymakers interested in biomass solid fuel.
Biomass solid fuel (BSF) has emerged as a promising renewable energy source, but its morphological and microstructural properties are crucial in determining their physical, mechanical, and chemical characteristics. This paper provides an overview of recent research on BSF. The focus is on biomass sources, BSF processing methods, and morphological and microstructural properties, with a special emphasis on energy-related studies. Specific inclusion and exclusion criteria were established for the study to ensure relevance. The inclusion criteria encompassed studies about BSFs and studies investigating the influence of biomass sources and processing methods on the morphological and microstructural properties of solid fuels within the past five years. Various technologies for converting biomass into usable energy were discussed, including gasification, torrefaction, carbonization, hydrothermal carbonization (HTC), and pyrolysis. Each has advantages and disadvantages in energy performance, techno-economics, and climate impact. Gasification is efficient but requires high investment. Pyrolysis produces bio-oil, char, and gases based on feedstock availability. Carbonization generates low-cost biochar for solid fuels and carbon sequestration applications. Torrefaction increases energy density for co-firing with coal. HTC processes wet biomass efficiently with lower energy input. Thermal treatment affects BSF durability and strength, often leading to less durability due to voids and gaps between particles. Hydrothermal carbonization alters surface morphology, creating cavities, pores, and distinctive shapes. Slow pyrolysis generates biochar with better morphological properties, while fast pyrolysis yields biochar with lower porosity and surface area. Wood constitutes 67% of the biomass sources utilized for bioenergy generation, followed by wood residues (5%), agro-residues (4%), municipal solid wastes (3%), energy crops (3%), livestock wastes (3%), and forest residues (1%). Each source has advantages and drawbacks, such as availability, cost, environmental impact, and suitability for specific regions and energy requirements. This review is valuable for energy professionals, researchers, and policymakers interested in biomass solid fuel.
2023, 8(4): 361-387.
doi: 10.1016/j.jobab.2023.06.005
Abstract:
Conventional plastics exacerbate climate change by generating substantial amounts of greenhouse gases and solid wastes throughout their lifecycle. To address the environmental and economic challenges associated with petroleum-based plastics, bioplastics have emerged as a viable alternative. Bioplastics are a type of plastic that are either biobased, biodegradable, or both. Due to their biodegradability and renewability, bioplastics are established as earth-friendly materials that can replace nonrenewable plastics. However, early bioplastic development has been hindered by higher production costs and inferior mechanical and barrier properties compared to conventional plastics. Nevertheless, studies have shown that the addition of additives and fillers can enhance bioplastic properties. Recent advancements in bioplastics have incorporated special additives like antibacterial, antifungal, and antioxidant agents, offering added values and unique properties for specific applications in various sectors. For instance, integrating antibacterial additives into bioplastics enables the creation of active food packaging, extending the shelf-life of food by inhibiting spoilage-causing bacteria and microorganisms. Moreover, bioplastics with antioxidant additives can be applied in wound dressings, accelerating wound healing by preventing oxidative damage to cells and tissues. These innovative bioplastic developments offer promising opportunities for developing sustainable and practical solutions in various fields. Within this review are two main focuses: an outline of the bioplastic classifications to understand how they fit in as the coveted conventional plastics substitute and an overview of the recent bioplastic innovations in the antibacterial, antifungal, and antioxidant applications. We cover the use of different polymers and additives, presenting the findings and potential applications within the last decade. Although current research primarily focuses on food packaging and biomedicine, the exploration of bioplastics with specialized properties is still in its early stages, offering a wide range of undiscovered opportunities.
Conventional plastics exacerbate climate change by generating substantial amounts of greenhouse gases and solid wastes throughout their lifecycle. To address the environmental and economic challenges associated with petroleum-based plastics, bioplastics have emerged as a viable alternative. Bioplastics are a type of plastic that are either biobased, biodegradable, or both. Due to their biodegradability and renewability, bioplastics are established as earth-friendly materials that can replace nonrenewable plastics. However, early bioplastic development has been hindered by higher production costs and inferior mechanical and barrier properties compared to conventional plastics. Nevertheless, studies have shown that the addition of additives and fillers can enhance bioplastic properties. Recent advancements in bioplastics have incorporated special additives like antibacterial, antifungal, and antioxidant agents, offering added values and unique properties for specific applications in various sectors. For instance, integrating antibacterial additives into bioplastics enables the creation of active food packaging, extending the shelf-life of food by inhibiting spoilage-causing bacteria and microorganisms. Moreover, bioplastics with antioxidant additives can be applied in wound dressings, accelerating wound healing by preventing oxidative damage to cells and tissues. These innovative bioplastic developments offer promising opportunities for developing sustainable and practical solutions in various fields. Within this review are two main focuses: an outline of the bioplastic classifications to understand how they fit in as the coveted conventional plastics substitute and an overview of the recent bioplastic innovations in the antibacterial, antifungal, and antioxidant applications. We cover the use of different polymers and additives, presenting the findings and potential applications within the last decade. Although current research primarily focuses on food packaging and biomedicine, the exploration of bioplastics with specialized properties is still in its early stages, offering a wide range of undiscovered opportunities.
2023, 8(4): 388-398.
doi: 10.1016/j.jobab.2023.06.003
Abstract:
Carbothermal reduction using biochar (BC) is a green and effective method of synthesizing BC-supported nanoscale zero-valent iron (nanoFe0) composites. However, the effect of BC surface area on the structure, distribution, and performance such as the heavy metal uptake capacity of nanoFe0 particles remains unclear. Soybean stover-based BCs with different surface areas (1.7 − 1 472 m2/g) were prepared in this study. They have been used for in-situ synthesis BCs-supported nanoFe0 particles through carbothermal reduction of ferrous chloride. The BCs-supported nanoFe0 particles were found to be covered with graphene shells and dispersed onto BC surfaces, forming the BC-supported graphene-encapsulated nanoFe0 (BC-G@Fe0) composite. These graphene shells covering the nanoFe0 particles were formed because of gaseous carbon evolved from biomass carbonization reacting with iron oxides/iron salts. Increasing BC surface area decreased the average diameters of nanoFe0 particles, indicating a higher BC surface area alleviated the aggregation of nanoFe0 particles, which resulted in higher heavy metal uptake capacity. At the optimized condition, BC-G@Fe0 composite exhibited uptake capacities of 124.4, 121.8, 254.5, and 48.0 mg/g for Cu2+, Pb2+, Ag+, and As3+, respectively (pH 5, 25 ℃). Moreover, the BC-G@Fe0 composite also demonstrated high stability for Cu2+ removal from the fixed-bed continuous flow, in which 1 g of BC-G@Fe0 can work for 120 h in a 4 mg/L Cu2+ flow continually and clean 28.6 L Cu2+ contaminated water. Furthermore, the BC-G@Fe0 composite can effectively immobilize the bioavailable As3+ from the contaminated soil, i.e., 5% (w) of BC-G@Fe0 composite addition can immobilize up to 92.2% bioavailable As3+ from the contaminated soil.
Carbothermal reduction using biochar (BC) is a green and effective method of synthesizing BC-supported nanoscale zero-valent iron (nanoFe0) composites. However, the effect of BC surface area on the structure, distribution, and performance such as the heavy metal uptake capacity of nanoFe0 particles remains unclear. Soybean stover-based BCs with different surface areas (1.7 − 1 472 m2/g) were prepared in this study. They have been used for in-situ synthesis BCs-supported nanoFe0 particles through carbothermal reduction of ferrous chloride. The BCs-supported nanoFe0 particles were found to be covered with graphene shells and dispersed onto BC surfaces, forming the BC-supported graphene-encapsulated nanoFe0 (BC-G@Fe0) composite. These graphene shells covering the nanoFe0 particles were formed because of gaseous carbon evolved from biomass carbonization reacting with iron oxides/iron salts. Increasing BC surface area decreased the average diameters of nanoFe0 particles, indicating a higher BC surface area alleviated the aggregation of nanoFe0 particles, which resulted in higher heavy metal uptake capacity. At the optimized condition, BC-G@Fe0 composite exhibited uptake capacities of 124.4, 121.8, 254.5, and 48.0 mg/g for Cu2+, Pb2+, Ag+, and As3+, respectively (pH 5, 25 ℃). Moreover, the BC-G@Fe0 composite also demonstrated high stability for Cu2+ removal from the fixed-bed continuous flow, in which 1 g of BC-G@Fe0 can work for 120 h in a 4 mg/L Cu2+ flow continually and clean 28.6 L Cu2+ contaminated water. Furthermore, the BC-G@Fe0 composite can effectively immobilize the bioavailable As3+ from the contaminated soil, i.e., 5% (w) of BC-G@Fe0 composite addition can immobilize up to 92.2% bioavailable As3+ from the contaminated soil.
2023, 8(4): 399-407.
doi: 10.1016/j.jobab.2023.07.001
Abstract:
Disposable face masks are an essential piece of personal protective equipment for workers in medical facilities, laboratories, and the general public to prevent the spread of illnesses and/or contamination. Covid-19 resulted in an uptick in the usage and production of face masks, exacerbating issues related to the waste and recycling of these materials. Traditionally, face masks are derived from petrochemicals, such as melt-blown or spunbound polypropylene. As such, there is a need to find sustainable mask materials that can maintain or improve the performance of petrochemical masks. This paper explores an alternative mask material that utilizes fungal mycelium as self-growing filaments to enhance the efficiency of individual polypropylene mask layers. By engineering the growth pattern and time, breathability and filtration efficiency was optimized such that one layer of the mycelium-modified mask could replace all three layers of the traditional three-layer mask. Additionally, it was found that the mycelium-modified mask exhibits asymmetric hydrophobicity, with super-hydrophobicity at the composite-air interface and lower hydrophobicity at the composite-medium interface. This property can improve the performance of the modified mask by protecting the mask from external liquids without trapping water vapor from the user's breath. The findings from this study can provide a basis for further development of mycelium to create sustainable filtration materials with enhanced functionality.
Disposable face masks are an essential piece of personal protective equipment for workers in medical facilities, laboratories, and the general public to prevent the spread of illnesses and/or contamination. Covid-19 resulted in an uptick in the usage and production of face masks, exacerbating issues related to the waste and recycling of these materials. Traditionally, face masks are derived from petrochemicals, such as melt-blown or spunbound polypropylene. As such, there is a need to find sustainable mask materials that can maintain or improve the performance of petrochemical masks. This paper explores an alternative mask material that utilizes fungal mycelium as self-growing filaments to enhance the efficiency of individual polypropylene mask layers. By engineering the growth pattern and time, breathability and filtration efficiency was optimized such that one layer of the mycelium-modified mask could replace all three layers of the traditional three-layer mask. Additionally, it was found that the mycelium-modified mask exhibits asymmetric hydrophobicity, with super-hydrophobicity at the composite-air interface and lower hydrophobicity at the composite-medium interface. This property can improve the performance of the modified mask by protecting the mask from external liquids without trapping water vapor from the user's breath. The findings from this study can provide a basis for further development of mycelium to create sustainable filtration materials with enhanced functionality.
2023, 8(4): 408-420.
doi: 10.1016/j.jobab.2023.10.001
Abstract:
In this study, the influence of thermoforming conditions on the resulting material properties was investigated, which aimed at developing advanced wood-fiber-based materials for the replacement of fossil plastics. Two bleached softwood pulps were studied, i.e., northern bleached softwood Kraft pulp (NBSK) and chemi-thermomechanical softwood pulp (CTMP). The thermoforming conditions were varied between 2–100 MPa and 150–200 ℃, while pressing sheets of 500 g/m2 for 10 min to represent thin-walled packaging more closely. As our results showed, the temperature had a more pronounced effect on the CTMP substrates than on the Kraft pulp. This was explained by the greater abundance of lignin and hemicelluloses, while fibrillar dimensions and the fines content may play a role in addition. Moreover, the CTMP exhibited an optimum in terms of tensile strength at intermediate thermoforming pressure. This effect was attributed to two counteracting effects: 1) Improved fiber adhesion due to enhanced densification, and 2) embrittlement caused by the loss of extensibility. High temperatures likely softened the lignin, enabling fiber collapse and a tighter packing. For the Kraft substrates, the tensile strength increased linearly with density. Both pulps showed reduced wetting at elevated thermoforming temperature and pressure, which was attributed to hornification and densification effects. Here, the effect of temperature was again more pronounced for CTMP than for the Kraft fibers. It was concluded that the thermoforming temperature and pressure strongly affected the properties of the final material. The chemical composition of the pulps will distinctly affect their response to thermoforming, which could be useful for tailoring cellulose-based replacements for packaging products.
In this study, the influence of thermoforming conditions on the resulting material properties was investigated, which aimed at developing advanced wood-fiber-based materials for the replacement of fossil plastics. Two bleached softwood pulps were studied, i.e., northern bleached softwood Kraft pulp (NBSK) and chemi-thermomechanical softwood pulp (CTMP). The thermoforming conditions were varied between 2–100 MPa and 150–200 ℃, while pressing sheets of 500 g/m2 for 10 min to represent thin-walled packaging more closely. As our results showed, the temperature had a more pronounced effect on the CTMP substrates than on the Kraft pulp. This was explained by the greater abundance of lignin and hemicelluloses, while fibrillar dimensions and the fines content may play a role in addition. Moreover, the CTMP exhibited an optimum in terms of tensile strength at intermediate thermoforming pressure. This effect was attributed to two counteracting effects: 1) Improved fiber adhesion due to enhanced densification, and 2) embrittlement caused by the loss of extensibility. High temperatures likely softened the lignin, enabling fiber collapse and a tighter packing. For the Kraft substrates, the tensile strength increased linearly with density. Both pulps showed reduced wetting at elevated thermoforming temperature and pressure, which was attributed to hornification and densification effects. Here, the effect of temperature was again more pronounced for CTMP than for the Kraft fibers. It was concluded that the thermoforming temperature and pressure strongly affected the properties of the final material. The chemical composition of the pulps will distinctly affect their response to thermoforming, which could be useful for tailoring cellulose-based replacements for packaging products.
2023, 8(4): 421-429.
doi: 10.1016/j.jobab.2023.06.004
Abstract:
Passive cooling strategy shows great potential in mitigating global warming and reducing energy consumption. Because of the high emissivity in the atmospheric transparency window (λ ≈ 8–13 µm), cellulose is considered as a good candidate for radiative cooling. However, traditional cellulose coolers generally show poor solar reflection and can be polluted by dust outside, thereby resulting in poor daytime cooling efficiency. To address these drawbacks, we developed sustainable cellulose nanowhiskers (CNWs)/ZnO composite aerogel films with favorable optical performance, mechanical robustness, and self-cleaning function for efficient daytime radiative cooling, which can be achieved via freeze casting and hot-pressing process. Due to formation of multi-level porous structure and chemical bonds (Si-O-C/Si-O-Si), such aerogel film exhibited high solar reflectance (97%) and high infrared emittance (92.5%). It achieved a sub-ambient temperature drop of 6.9 ℃ under direct sunlight in hot weather. Most importantly, the surface roughness and low surface energy enable cellulose aerogel film hydrophobicity (contact angle = 133°), thereby resulting in an anti-dust function. This work provides insight into the design of sustainable thermal regulating materials to realize carbon neutrality.
Passive cooling strategy shows great potential in mitigating global warming and reducing energy consumption. Because of the high emissivity in the atmospheric transparency window (λ ≈ 8–13 µm), cellulose is considered as a good candidate for radiative cooling. However, traditional cellulose coolers generally show poor solar reflection and can be polluted by dust outside, thereby resulting in poor daytime cooling efficiency. To address these drawbacks, we developed sustainable cellulose nanowhiskers (CNWs)/ZnO composite aerogel films with favorable optical performance, mechanical robustness, and self-cleaning function for efficient daytime radiative cooling, which can be achieved via freeze casting and hot-pressing process. Due to formation of multi-level porous structure and chemical bonds (Si-O-C/Si-O-Si), such aerogel film exhibited high solar reflectance (97%) and high infrared emittance (92.5%). It achieved a sub-ambient temperature drop of 6.9 ℃ under direct sunlight in hot weather. Most importantly, the surface roughness and low surface energy enable cellulose aerogel film hydrophobicity (contact angle = 133°), thereby resulting in an anti-dust function. This work provides insight into the design of sustainable thermal regulating materials to realize carbon neutrality.
2023, 8(4): 430-443.
doi: 10.1016/j.jobab.2023.09.003
Abstract:
In this study, we attempted to characterise the effects of date-palm fibre (DPF) and a date-palm fibre/sheep wool hybrid in polyester to enhance high-performance and low-cost composite materials that can be used in insulation building systems, automotive parts, and home furniture. The DPF was treated using 5 % NaOH solution; and the sheep wool was cleaned with 50 ℃ hot water and detergents. The composite specimens were prepared with different fibre contents (0 %, 10 %, 20 %, 30 % (w)) using a compression moulding technique. The effect of fibre reinforcement was analysed in terms of the mechanical properties (tensile, flexural, impact, and hardness) and composite density. Additionally, scanning electron microscopy (SEM) was performed on the fibres before and after treatment, and the fractured surfaces of all composite specimens were examined after tensile testing. The results showed that the 20 % DPF/sheep wool hybrid reinforced polyester produced the best results. The ultimate tensile strength and modulus were 27 MPa and 3.69 GPa, respectively. The ultimate flexural strength and flexural modulus were 35.4 and 2507 MPa, respectively. The impact strength was 39.5 kJ/m2 and the hardness was 64 HB. The density decreased to the lowest value of 1.02 g/cm3 with the 30 % DPF/sheep wool hybrid. The SEM showed good adhesion and interfacial bonding between DPF/sheep wool hybrid fibres and the polyester matrix, particularly at 20 % fibre content.
In this study, we attempted to characterise the effects of date-palm fibre (DPF) and a date-palm fibre/sheep wool hybrid in polyester to enhance high-performance and low-cost composite materials that can be used in insulation building systems, automotive parts, and home furniture. The DPF was treated using 5 % NaOH solution; and the sheep wool was cleaned with 50 ℃ hot water and detergents. The composite specimens were prepared with different fibre contents (0 %, 10 %, 20 %, 30 % (w)) using a compression moulding technique. The effect of fibre reinforcement was analysed in terms of the mechanical properties (tensile, flexural, impact, and hardness) and composite density. Additionally, scanning electron microscopy (SEM) was performed on the fibres before and after treatment, and the fractured surfaces of all composite specimens were examined after tensile testing. The results showed that the 20 % DPF/sheep wool hybrid reinforced polyester produced the best results. The ultimate tensile strength and modulus were 27 MPa and 3.69 GPa, respectively. The ultimate flexural strength and flexural modulus were 35.4 and 2507 MPa, respectively. The impact strength was 39.5 kJ/m2 and the hardness was 64 HB. The density decreased to the lowest value of 1.02 g/cm3 with the 30 % DPF/sheep wool hybrid. The SEM showed good adhesion and interfacial bonding between DPF/sheep wool hybrid fibres and the polyester matrix, particularly at 20 % fibre content.
2023, 8(4): 444-460.
doi: 10.1016/j.jobab.2023.10.002
Abstract:
Because of socioeconomic considerations, wide-scale production of biofuel necessitates the utilization of nonedible biomass feedstock that does not compete for land and fresh water resources. In this regard, Salicornia bigelovii (SB) is the most investigated halophyte species. The high oil content in SB seeds has sparked mounting research that aims to utilize SB as an industrial crop in the production of bio-oil, particularly in coastal areas where these plants thrive. However, the oil extracted from the pyrolysis of raw SB seeds is largely dominated by oxygenated fatty acids, most notably 9, 12-octadecadienoic acid and 9, 17-octadecadienal, typical to that of other crops. The pyrolysate bio-oil of the raw SB seeds exhibited a relative yield of oxygenated compounds that decreased from 57.05 % at 200 ℃ to 9.81 % at 500 ℃, and the relative yield of nitrogenated compounds increased from 4.86 % at 200 ℃ to 21.97 % at 500 ℃. To improve the quality of the produced bio-oil, herein we investigated the catalytic hydrodeoxygenation (HDO) of the fragments that were produced from the thermal degradation of SB seeds. A 5 %Ni–CeO2 catalyst was prepared and characterized by a wide array of methods X-ray diffraction, X-ray photoelectron spectroscopy, temperature programmed reduction, scanning electron microscope, Brunauer-Emmett-Teller analysis, and thermogravimetric analyzer. The catalytic run was executed between 200 and 500 ℃ in a flow reactor. The deployed catalytic methodology displayed a profound HDO capacity. At 400 ℃, for instance, the gas chromatography mass spectroscopy (GC–MS) detected loads of paraffin and aromatic compounds exists at appreciable values of 48.0 % and 28.5 %, respectively. With a total relative yield of 43.2 % (at 400 ℃), C8–C15 species (i.e., jet fuel fractions) were the most abundant species in the upgraded SB bio-oil. The release of H2, CO, CO2, and CH4 was analyzed qualitatively and quantitatively using gas chromatography thermal conductivity detector and Fourier infrared spectroscopic analysis. When the Ni–CeO2 catalyst was utilized, a complete deoxygenated bio-oil was obtained from SB seeds using the surface-assisted HDO reaction. On the basis of the elemental analysis, the biochar's hydrogen and oxygen contents were found to decrease significantly. Density functional theory computations showed mechanisms for reactions that underpinned the experimentally observed hydrodeoxygenation process. Outcomes presented herein shall be instrumental toward the effective utilization of halophyte in the production of commercial transportation fuels.
Because of socioeconomic considerations, wide-scale production of biofuel necessitates the utilization of nonedible biomass feedstock that does not compete for land and fresh water resources. In this regard, Salicornia bigelovii (SB) is the most investigated halophyte species. The high oil content in SB seeds has sparked mounting research that aims to utilize SB as an industrial crop in the production of bio-oil, particularly in coastal areas where these plants thrive. However, the oil extracted from the pyrolysis of raw SB seeds is largely dominated by oxygenated fatty acids, most notably 9, 12-octadecadienoic acid and 9, 17-octadecadienal, typical to that of other crops. The pyrolysate bio-oil of the raw SB seeds exhibited a relative yield of oxygenated compounds that decreased from 57.05 % at 200 ℃ to 9.81 % at 500 ℃, and the relative yield of nitrogenated compounds increased from 4.86 % at 200 ℃ to 21.97 % at 500 ℃. To improve the quality of the produced bio-oil, herein we investigated the catalytic hydrodeoxygenation (HDO) of the fragments that were produced from the thermal degradation of SB seeds. A 5 %Ni–CeO2 catalyst was prepared and characterized by a wide array of methods X-ray diffraction, X-ray photoelectron spectroscopy, temperature programmed reduction, scanning electron microscope, Brunauer-Emmett-Teller analysis, and thermogravimetric analyzer. The catalytic run was executed between 200 and 500 ℃ in a flow reactor. The deployed catalytic methodology displayed a profound HDO capacity. At 400 ℃, for instance, the gas chromatography mass spectroscopy (GC–MS) detected loads of paraffin and aromatic compounds exists at appreciable values of 48.0 % and 28.5 %, respectively. With a total relative yield of 43.2 % (at 400 ℃), C8–C15 species (i.e., jet fuel fractions) were the most abundant species in the upgraded SB bio-oil. The release of H2, CO, CO2, and CH4 was analyzed qualitatively and quantitatively using gas chromatography thermal conductivity detector and Fourier infrared spectroscopic analysis. When the Ni–CeO2 catalyst was utilized, a complete deoxygenated bio-oil was obtained from SB seeds using the surface-assisted HDO reaction. On the basis of the elemental analysis, the biochar's hydrogen and oxygen contents were found to decrease significantly. Density functional theory computations showed mechanisms for reactions that underpinned the experimentally observed hydrodeoxygenation process. Outcomes presented herein shall be instrumental toward the effective utilization of halophyte in the production of commercial transportation fuels.
2023, 8(4): 461-477.
doi: 10.1016/j.jobab.2023.09.004
Abstract:
Low lignin solubility in aqueous solution is one of the major bottlenecks for lignin biodegradation and bioconversion. Alkaline solution contributes to improving lignin solubility, whereas most microbes can not survive in alkaline conditions. Herein, lignin dissolution behaviors in different pH solutions were systematically investigated, which indicated that solution pH above 10.5 contributed to high solubility of alkali lignin. To match with alkaline lignin aqueous system, several alkali-tolerant ligninolytic bacteria were isolated, most of which are distinct to previously reported ones. Then, the ligninolytic capabilities of these isolates were assessed in different pH conditions by determining their assimilation on alkali lignin, lignin-derived monomers and dimers, their decolorization capabilities, and their lignin peroxidase activities. Thereafter, the underlying ligninolytic and alkali-tolerant mechanisms of Sutcliffiella sp. NC1, an alkalophilic bacterium, was analyzed on the basis of its genome information. The results not only provide valuable information for lignin biodegradation and lignin valorization, but also expand knowledge on alkali-tolerant bacteria.
Low lignin solubility in aqueous solution is one of the major bottlenecks for lignin biodegradation and bioconversion. Alkaline solution contributes to improving lignin solubility, whereas most microbes can not survive in alkaline conditions. Herein, lignin dissolution behaviors in different pH solutions were systematically investigated, which indicated that solution pH above 10.5 contributed to high solubility of alkali lignin. To match with alkaline lignin aqueous system, several alkali-tolerant ligninolytic bacteria were isolated, most of which are distinct to previously reported ones. Then, the ligninolytic capabilities of these isolates were assessed in different pH conditions by determining their assimilation on alkali lignin, lignin-derived monomers and dimers, their decolorization capabilities, and their lignin peroxidase activities. Thereafter, the underlying ligninolytic and alkali-tolerant mechanisms of Sutcliffiella sp. NC1, an alkalophilic bacterium, was analyzed on the basis of its genome information. The results not only provide valuable information for lignin biodegradation and lignin valorization, but also expand knowledge on alkali-tolerant bacteria.
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