7 results found
Chambon CL, Chen M, Fennell PS, et al., 2019, Efficient fractionation of lignin- and ash-rich agricultural residues following treatment with a low-cost protic ionic liquid, Frontiers in Chemistry, Vol: 7, ISSN: 2296-2646
Agricultural residues from rice, wheat and sugarcane production are annually available at the gigaton-scale worldwide, particularly in Asia. Due to their high sugar content and ash compositions, their conversion to bioethanol is an attractive alternative to their present disposal by open-field burning and landfilling. In this work, we demonstrate application of the low-cost protic ionic liquid triethylammonium hydrogen sulfate ([TEA][HSO4]) for pretreatment of rice straw, rice husk, wheat straw and sugarcane bagasse. The feedstocks had high ash (up to 13 wt%) and lignin content (up to 28 wt%). Pretreatment effectiveness was examined at 150 and 170°C and an optimal pretreatment time was identified and characterized by glucose release following enzymatic saccharification (i.e., hydrolysis), biomass delignification observed by compositional analysis, and lignin recovery. The isolated lignin fractions were analyzed by 2D HSQC NMR to obtain insights into the structural changes occurring following ionic liquid pretreatment. After treatment at 170°C for 30–45 min, enzymatic hydrolysis of three agroresidues gave near-quantitative glucose yields approaching 90% while rice husk gave 73% yield. Glucose release from the pulps was enhanced by saccharifying wet pulps without an air-drying step to reduce hornification. According to pulp compositional analysis, up to 82% of lignin was removed from biomass during pretreatment, producing highly digestible cellulose-rich pulps. HSQC NMR of the extracted lignins showed that delignification proceeded via extensive cleavage of β-O-4′ aryl ether linkages which was accompanied by condensation reactions in the isolated lignins. The high saccharification yields obtained indicate excellent potential for valorization of low-cost agroresidues in large volumes, which is promising for commercialization of biofuels production using the ionoSolv pretreatment technology.
Gschwend F, Chambon C, Biedka M, et al., 2019, Quantitative glucose release from softwood after pretreatment with low-cost ionic liquids, Green Chemistry, Vol: 21, Pages: 692-703, ISSN: 1463-9262
Softwood is an abundantly available feedstock for the bio-based industry, however, achieving cost-effective sugar release is particularly challenging owing to its guaiacyl-only lignin. Here, we report the highly effective pretreatment of the softwood pine (Pinus sylvestris) using ionoSolv pretreatment, a novel ionic liquid-based lignocellulose fractionation technology. Three protic, low-cost ionic liquids, 1-butylimidazolium hydrogen sulfate, triethylammonium hydrogen sulfate and N,N-dimethylbutylammonium hydrogen sulfate, were used to fractionate the biomass into a carbohydrate-rich pulp and a lignin. The carbohydrate-rich pulp was hydrolysed into fermentable sugars by enzymatic saccharification. Under the most successful pretreatment conditions, quantitative glucose release from the pulp was achieved, which equates to a projected glucose release of 464 mg per gram of pine wood entering the process. We further intensified the process by increasing the solid to solvent ratio up to 1:2 g/g while maintaining saccharification yields of 75% of the theoretical maximum. We also demonstrate for the first time that N,N-dimethylbutylammonium hydrogen sulfate, [DMBA][HSO4] is an excellent low-cost pretreatment solvent, surpassing the pretreatment effectiveness of its symmetrically substituted analogue triethylammonium hydrogen sulfate. This shows that ionoSolv pretreatment with protic hydrogen sulfate ionic liquids is a truly feedstock-independent pretreatment option, further increasing the commercial potential of this pretreatment technology.
Chambon C, Mkhize T, Reddy P, et al., 2018, Pretreatment of South African sugarcane bagasse using a low-cost protic ionic liquid: a comparison of whole, depithed, fibrous and pith bagasse fractions, Biotechnology for Biofuels, Vol: 11, ISSN: 1754-6834
BackgroundSugarcane bagasse is an abundant and geographically widespread agro-industrial residue with high carbohydrate content, making it a strong candidate feedstock for the bio-based economy. This study examines the use of the low-cost protic ionic liquid triethylammonium hydrogen sulfate ([TEA][HSO4]) to fractionate a range of South African sugarcane bagasse preparations into a cellulose-rich pulp and lignin. The study seeks to optimize pretreatment conditions and examine the necessity of applying a depithing step on bagasse prior to pretreatment.ResultsPretreatment of five bagasse preparations, namely whole, industrially depithed, laboratory depithed (short and long fiber) and pith bagasse with [TEA][HSO4]:[H2O] (4:1 w/w) solutions produced highly digestible cellulose-rich pulps, as assessed by residual lignin analysis and enzymatic hydrolysis. Pretreatment under the optimized condition of 120 °C for 4 h produced a pretreated cellulose pulp with up to 90% of the lignin removed and enabled the release of up to 69% glucose contained in the bagasse via enzymatic hydrolysis. Glucose yields from whole and depithed bagasse preparations were very similar. Significant differences in lignin recovery were obtained for laboratory depithed bagasse compared with whole and industrially depithed bagasse. The silica-rich ash components of bagasse were seen to partition mainly with the pulp, from where they could be easily recovered in the post-hydrolysis solids.ConclusionsThe five bagasse preparations were compared but did not show substantial differences in composition or cellulose digestibility after pretreatment. Evidence was presented that a depithing step appears to be unnecessary prior to ionoSolv fractionation, potentially affording significant cost and energy savings. Instead, lignin re-deposition onto the pulp surface (and, in turn, particle size and shape) appeared to be major factors affecting the conditioning of bagasse with the applied IL. We show that pith ba
Bond T, Tse Q, Chambon C, et al., 2018, The feasibility of char and bio-oil production from pyrolysis of pit latrine sludge, Environmental Science: Water Research and Technology, Vol: 4, Pages: 253-264, ISSN: 2053-1400
Sustainable methods are required in developing regions to treat and recover value from pit latrine sludge. One strategy is to pyrolyse pit latrine contents and generate char and bio-oil, which can then be used as a soil enhancer and fuel, respectively. Despite the many benefits associated with the process, there is very limited relevant literature available. This study examines its feasibility. Initially, the energy balance for the pyrolysis of sewage sludge was calculated using data from 14 literature studies. The average net energy recovery from pyrolysis of dewatered and dried sewage sludge followed by use of bio-oil as fuel was calculated as 4.95 ± 0.61 MJ kg−1. For dewatered sewage sludge, an average net energy input of 2.23 ± 0.31 MJ kg−1 was required. Parallel calculations were undertaken where pit latrine sludge with 0–100% water content was the hypothetical feedstock. On average, net energy recovery from produced bio-oil was achievable when pit latrine sludge with a water content of ≤∼55% was the feedstock. When both bio-oil and char were utilised, net energy recovery was feasible at a water content value of ≤∼65%. Char production is more favourable from stabilised pit latrine sludge with lower moisture and volatile solids content. Barriers to the pyrolysis of pit latrine sludge include its heterogeneous composition and the difficulty of collecting high-viscosity sludge. Overall, this study demonstrates the potential of pyrolysis as a disposal and value addition method for pit latrine sludge. Innovative methods for sludge drying and pit emptying will expedite the process becoming a reality.
Gschwend FJV, Brandt-Talbot A, Chambon CL, et al., 2017, Ultra-Low Cost Ionic Liquids for the Delignification of Biomass, Ionic Liquids: Current State and Future Directions, Editors: Shiflett, Scurto, Publisher: American Chemical Society, Pages: 209-223, ISBN: 9780841232136
Low-cost pretreatment of lignocellulosic biomass is an essential next step toward large-scale deployment as renewable liquid fuels, materials or chemicals. Ionic liquids (ILs) are highly effective at pretreatment, but high IL cost has hindered commercial viability. We have recently developed low-cost (ca. $1/kg) ILs, such as triethylammonium hydrogen sulphate, for pretreatment. In this chapter we discuss the fractionation of the grass Miscanthus x giganteus, wherein we deconstruct the lignocellulosic matrix into a cellulose-rich pulp, a recovered lignin fraction and an organic distillate. More than 80% of the lignin and quantitative hemicelluloses are removed during extraction. This results in 70-90% glucose release during enzymatic saccharification. The IL can also be successfully recovered and reused, with >99% IL recovery and minimal effects on efficiency of extraction. A detailed mass balance of all components and subsequent economic analysis revealed this efficient pretreatment with an ultra-low cost IL could result in an economically viable pretreatment process.
Sandwell P, Chambon C, Saraogi A, et al., 2016, Analysis of energy access and impact of modern energy sources in unelectrified villages in Uttar Pradesh, Energy for Sustainable Development, Vol: 35, Pages: 67-79, ISSN: 0973-0826
Bringingaccesstomodernenergysourcestothepoorestinsocietyisakeygoalofmanypolicymakers,businessesandcharities,butinorder tobea success projects and schemesmust be foundedonaccuratedata. We undertooka survey of energy demand and usage patterns in households in unelectrified villages in Uttar Pradesh, India toassess access to and utilisation of energy sources for lighting and cooking. The times of usage were recordedand analysed and the effect on usage patterns of transitioning from traditional to modern energy sourcesis assessed. We quantify the cost and greenhouse gas emissions of current energy use in order to provide abenchmark of potential mitigation through the use of renewable energy technologies: a typical householdwith kerosene lamps only for lighting spends INR 3243 (US$50.67) and emits 381 kgCO2eqper year; householdswithmoderncookingenergyspend17%morethroughincreasedusage,butemit28%lessgreenhousegasescom-pared to those with traditional stoves only. Cell phone ownership was found to be 50% amongst adults. We usedemographic and utilisation data to construct an hourly demand profile of basic electricity demand extrapolatedto each month of the year, and present an example of aspirational demand assess the impact of desirable appli-ances. A Monte Carlo simulation is used to highlight the daily and seasonal variation in total energy and powerdemand. A hybrid system, with solar power and battery storage meeting daytime demand and higher-capacitydiesel- or biomass-powered generation meeting the remainder during evening peaks and winter months,would satisfy demand most effectively.
Gschwend FJ, Brandt A, Chambon CL, et al., 2016, Pretreatment of Lignocellulosic Biomass with Low-cost Ionic Liquids., Jove-Journal of Visualized Experiments, Vol: 114, ISSN: 1940-087X
A number of ionic liquids (ILs) with economically attractive production costs have recently received growing interest as media for the delignification of a variety of lignocellulosic feedstocks. Here we demonstrate the use of these low-cost protic ILs in the deconstruction of lignocellulosic biomass (Ionosolv pretreatment), yielding cellulose and a purified lignin. In the most generic process, the protic ionic liquid is synthesized by accurate combination of aqueous acid and amine base. The water content is adjusted subsequently. For the delignification, the biomass is placed into a vessel with IL solution at elevated temperatures to dissolve the lignin and hemicellulose, leaving a cellulose-rich pulp ready for saccharification (hydrolysis to fermentable sugars). The lignin is later precipitated from the IL by the addition of water and recovered as a solid. The removal of the added water regenerates the ionic liquid, which can be reused multiple times. This protocol is useful to investigate the significant potential of protic ILs for use in commercial biomass pretreatment/lignin fractionation for producing biofuels or renewable chemicals and materials.
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