Deep eutectic solvents (DES) are new ‘green’ solvents that have a high potential for biomass proc... more Deep eutectic solvents (DES) are new ‘green’ solvents that have a high potential for biomass processing because of their low cost, low toxicity, biodegradability, and easy recycling. When Loblolly pine trees are harvested, their branches with needles are typically left in brush piles and decompose very slowly. Exploring the effect of DES pretreatment on waste pine needles was the goal of the present work. Loblolly pine needles were treated with three types of DES to prepare the biomass for enzymatic hydrolysis to glucose, a subject not readily found in the literature. The resulting products were analyzed by Fourier transform infrared spectroscopy, fiber analysis, and high-performance liquid chromatography. Glucose yields after pretreatment and hydrolysis were found to be six times that for untreated biomass with two of the DES. Fiber analysis indicated removal of lignin, hemicellulose, and ash from the needle biomass. Enhanced glucose yield was due to removal of lignin and disruptio...
An environmentally-friendly method to separate cellulose and hemicelluloses from lignin in recalc... more An environmentally-friendly method to separate cellulose and hemicelluloses from lignin in recalcitrant biomass for subsequent conversion is desirable to reduce greenhouse gas generation. Easily-prepared, deep eutectic solvents (DESs) have low volatility, wide liquid range, non-flammability, nontoxicity, biocompatibility, and biodegradability. This study shows the DESs (formic acid:choline chloride, lactic acid:choline chloride, acetic acid:choline chloride, lactic acid:betaine, and lactic acid:proline) to be capable of preferentially dissolving lignin at 60°C. Thermogravimetric analysis show DES to be stable at typical biomass processing temperatures. Pretreating loblolly pine in one DES increased glucose yield after enzymatic hydrolysis to more than seven times that of raw or glycerol-pretreated pine. The density of DES-pretreated biomass was found to be 40% higher than the untreated pine's density.
Environmental Progress & Sustainable Energy, 2013
Hydrothermal carbonization (HTC) is a process to densify, homogenize, and stabilize diverse bioma... more Hydrothermal carbonization (HTC) is a process to densify, homogenize, and stabilize diverse biomass feedstocks. The water requirements of HTC need to be assessed to determine commercial feasibility. This current research work focuses on the effects on HTC of using recycled process water for multiple process cycles. Loblolly pine was treated in hot, compressed water at 200, 230, and 260°C for 5 min with a 5:1 water:biomass mass ratio. Liquid product was separated and recycled for reuse in HTC, nine cycles at 200 and 230°C and five cycles at 260°C. The solid products (biocarbon) were characterized by their mass yields, higher heating values (HHVs), and equilibrium moisture content (EMC), whereas in the liquid samples, total organic carbon (TOC) content and pH were determined. With successive recycling, biocarbon mass yield increases by 5–10% above the yield recorded for the initial cycle at each temperature investigated, whereas biocarbon HHV is essentially unchanged. The aqueous TOC ...
Glycerol was used as a cosolvent with the two ionic liquids 1-ethyl-3-methylimidazolium formate (... more Glycerol was used as a cosolvent with the two ionic liquids 1-ethyl-3-methylimidazolium formate ([C2mim][O2CH]) and 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]) to pretreat loblolly pine at 140 °C. Enzymatic hydrolysis was then performed on raw and pretreated pines to establish pretreatment efficacy. With pretreatment, glucose yield from enzymatic hydrolysis was improved from 2 % for raw pine up to 43 %, while yields of mannose/xylose combined improved from 4 % up to 77 %. Pine pretreated with a 50 % [C2mim][O2CH]-50 % glycerol mixture exhibited a pulp-like structure, likely formed from removal of the lignin that binds cell walls together. Using this 50 % mixture of [C2mim][O2CH] and glycerol for pretreatment gave a slightly lower glucose yield than a 75 % mixture of [C2mim][O2CH] and glycerol but gave a mannose/xylose yield twice as high. Klason lignin and Fourier transform infrared spectroscopy (FTIR) analysis indicated that [C2mim][O2CH]-glycerol pretreatment preferentially dissolves lignin. FTIR analysis also suggested increased amorphous cellulose content with this pretreatment. Using the anti-solvent ethanol, a lignin-rich substance was precipitated from the solvent mixtures.
As a renewable non-food resource, biomass has great potential as an energy source or feedstock fo... more As a renewable non-food resource, biomass has great potential as an energy source or feedstock for further conversion. However, potential problems exist with transportation and storage of this geographically widely scattered and perishable resource. As a precursor to further thermochemical conversion, wet torrefaction treats any kind of biomass in 200 to 260C compressed water under a nitrogen atmosphere for a period of less than 20 minutes.. It is also known as hydrothermal carbonization or hot compressed water (HCW) treatment. The pretreated solid is about 60 80% of the mass of the originating solid, and has 80 95% of the fuel value of the original biomass feedstock. Byproducts include carbon dioxide, volatile organic acids such as acetic acid, precipitates of glucose and 5-hydroxymethyl furfural. Regardless of the initial form of biomass, the solid product has decreased equilibrium moisture content for longer shelf life, and increased fuel value. The solid product is friable, and ...
Biomass supply is complicated by diversity of feedstocks, seasonal availability, and widely distr... more Biomass supply is complicated by diversity of feedstocks, seasonal availability, and widely distributed feedstock. The costs of biomass supply and logistics hinder commercialization for advanced fuel and power production. Hydrothermal carbonization (HTC, or wet torrefaction) is a pretreatment process for making a homogenized, carbon rich, and energy dense solid fuel, called HTC biochar, from lignocellulosic biomass. Compared to raw biomass, HTC biochar is both more hydrophobic for better storage and more friable for better processing. In this pretreatment method, the biomass is treated with hot compressed water in an inert environment in the temperature range of 200-260°C. The range of mass yield of biochar is 60-90% and its energy yield is 75-95%, indicating that the process causes an energy densification of 6-25%. Higher reaction temperature decreases mass yield and increases energy densification. Kinetic data show that hemicelluloses and water extractives react very quickly compa...
Deep eutectic solvents (DES) are new ‘green’ solvents that have a high potential for biomass proc... more Deep eutectic solvents (DES) are new ‘green’ solvents that have a high potential for biomass processing because of their low cost, low toxicity, biodegradability, and easy recycling. When Loblolly pine trees are harvested, their branches with needles are typically left in brush piles and decompose very slowly. Exploring the effect of DES pretreatment on waste pine needles was the goal of the present work. Loblolly pine needles were treated with three types of DES to prepare the biomass for enzymatic hydrolysis to glucose, a subject not readily found in the literature. The resulting products were analyzed by Fourier transform infrared spectroscopy, fiber analysis, and high-performance liquid chromatography. Glucose yields after pretreatment and hydrolysis were found to be six times that for untreated biomass with two of the DES. Fiber analysis indicated removal of lignin, hemicellulose, and ash from the needle biomass. Enhanced glucose yield was due to removal of lignin and disruptio...
An environmentally-friendly method to separate cellulose and hemicelluloses from lignin in recalc... more An environmentally-friendly method to separate cellulose and hemicelluloses from lignin in recalcitrant biomass for subsequent conversion is desirable to reduce greenhouse gas generation. Easily-prepared, deep eutectic solvents (DESs) have low volatility, wide liquid range, non-flammability, nontoxicity, biocompatibility, and biodegradability. This study shows the DESs (formic acid:choline chloride, lactic acid:choline chloride, acetic acid:choline chloride, lactic acid:betaine, and lactic acid:proline) to be capable of preferentially dissolving lignin at 60°C. Thermogravimetric analysis show DES to be stable at typical biomass processing temperatures. Pretreating loblolly pine in one DES increased glucose yield after enzymatic hydrolysis to more than seven times that of raw or glycerol-pretreated pine. The density of DES-pretreated biomass was found to be 40% higher than the untreated pine's density.
Environmental Progress & Sustainable Energy, 2013
Hydrothermal carbonization (HTC) is a process to densify, homogenize, and stabilize diverse bioma... more Hydrothermal carbonization (HTC) is a process to densify, homogenize, and stabilize diverse biomass feedstocks. The water requirements of HTC need to be assessed to determine commercial feasibility. This current research work focuses on the effects on HTC of using recycled process water for multiple process cycles. Loblolly pine was treated in hot, compressed water at 200, 230, and 260°C for 5 min with a 5:1 water:biomass mass ratio. Liquid product was separated and recycled for reuse in HTC, nine cycles at 200 and 230°C and five cycles at 260°C. The solid products (biocarbon) were characterized by their mass yields, higher heating values (HHVs), and equilibrium moisture content (EMC), whereas in the liquid samples, total organic carbon (TOC) content and pH were determined. With successive recycling, biocarbon mass yield increases by 5–10% above the yield recorded for the initial cycle at each temperature investigated, whereas biocarbon HHV is essentially unchanged. The aqueous TOC ...
Glycerol was used as a cosolvent with the two ionic liquids 1-ethyl-3-methylimidazolium formate (... more Glycerol was used as a cosolvent with the two ionic liquids 1-ethyl-3-methylimidazolium formate ([C2mim][O2CH]) and 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]) to pretreat loblolly pine at 140 °C. Enzymatic hydrolysis was then performed on raw and pretreated pines to establish pretreatment efficacy. With pretreatment, glucose yield from enzymatic hydrolysis was improved from 2 % for raw pine up to 43 %, while yields of mannose/xylose combined improved from 4 % up to 77 %. Pine pretreated with a 50 % [C2mim][O2CH]-50 % glycerol mixture exhibited a pulp-like structure, likely formed from removal of the lignin that binds cell walls together. Using this 50 % mixture of [C2mim][O2CH] and glycerol for pretreatment gave a slightly lower glucose yield than a 75 % mixture of [C2mim][O2CH] and glycerol but gave a mannose/xylose yield twice as high. Klason lignin and Fourier transform infrared spectroscopy (FTIR) analysis indicated that [C2mim][O2CH]-glycerol pretreatment preferentially dissolves lignin. FTIR analysis also suggested increased amorphous cellulose content with this pretreatment. Using the anti-solvent ethanol, a lignin-rich substance was precipitated from the solvent mixtures.
As a renewable non-food resource, biomass has great potential as an energy source or feedstock fo... more As a renewable non-food resource, biomass has great potential as an energy source or feedstock for further conversion. However, potential problems exist with transportation and storage of this geographically widely scattered and perishable resource. As a precursor to further thermochemical conversion, wet torrefaction treats any kind of biomass in 200 to 260C compressed water under a nitrogen atmosphere for a period of less than 20 minutes.. It is also known as hydrothermal carbonization or hot compressed water (HCW) treatment. The pretreated solid is about 60 80% of the mass of the originating solid, and has 80 95% of the fuel value of the original biomass feedstock. Byproducts include carbon dioxide, volatile organic acids such as acetic acid, precipitates of glucose and 5-hydroxymethyl furfural. Regardless of the initial form of biomass, the solid product has decreased equilibrium moisture content for longer shelf life, and increased fuel value. The solid product is friable, and ...
Biomass supply is complicated by diversity of feedstocks, seasonal availability, and widely distr... more Biomass supply is complicated by diversity of feedstocks, seasonal availability, and widely distributed feedstock. The costs of biomass supply and logistics hinder commercialization for advanced fuel and power production. Hydrothermal carbonization (HTC, or wet torrefaction) is a pretreatment process for making a homogenized, carbon rich, and energy dense solid fuel, called HTC biochar, from lignocellulosic biomass. Compared to raw biomass, HTC biochar is both more hydrophobic for better storage and more friable for better processing. In this pretreatment method, the biomass is treated with hot compressed water in an inert environment in the temperature range of 200-260°C. The range of mass yield of biochar is 60-90% and its energy yield is 75-95%, indicating that the process causes an energy densification of 6-25%. Higher reaction temperature decreases mass yield and increases energy densification. Kinetic data show that hemicelluloses and water extractives react very quickly compa...
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