Biorefinery Process Research Articles

Valorization of White Lupin Straw Through Mild Dilute Acid Hydrothermal Treatment: A Sustainable Route for Monosaccharide and 5-Hydroxymethylfurfural Production

This study investigates the potential use of white lupine straw (WLS), an underutilized agricultural by-product, as a raw material to produce valuable biochemicals such as monosaccharides and 5-hydroxymethylfurfural (5-HMF) through hydrothermal pretreatment. The aim was to optimize mild reaction conditions to maximize the recovery of these products while minimizing degradation. The hydrothermal treatment of WLS in subcritical water with trace amounts of sulfuric acid was performed, followed by a two-step approach to evaluate the yields of hemicellulose and 5-HMF. The highest monosaccharide yield (163 g/kg) was achieved at temperatures between 174 and 181 °C and a holding time of 7–14 min, while the 5-HMF production was 139.9 g/kg at 199–203 °C and after 0.5–4.5 min. These results suggest that optimal 5-HMF production also increases the remaining solid residue. This study highlights the feasibility of WLS as a sustainable, low-cost biomass resource. It highlights the balance between temperature and time to maximize valuable product yields. The results contribute to advancing biorefinery processes by demonstrating that WLS can be effectively converted into bioethanol precursors and industrial chemicals, supporting circular bioeconomy principles and providing an environmentally friendly alternative to burning crop residues.

Advanced Biofuel Value Chains Sourced by New Cropping Systems With Low iLUC Risk

ABSTRACTIncreasing lignocellulosic feedstock for advanced biofuels can tackle the decarbonization of the transport sector. Dedicated biomass produced alongside food systems with low indirect land use change (iLUC) impact can broaden the feedstock availability, thus streamlining the supply chains. The objective of this study was the design and evaluation of advanced ethanol value chains for the Emilia‐Romagna region based on low iLUC feedstock. Two dedicated lignocellulosic crops (biomass sorghum and sunn hemp) were evaluated in double cropping systems alongside food crop residues (corn stover and wheat straw) as sources to simulate the value chains. A parcel‐level regional analysis was carried out, then the LocaGIStics2.0 model was used for the spatial design and review of the biomass delivery chain options regarding cost and greenhouse gas (GHG) emissions of the different feedstock mixes. Literature data on bioethanol production from similar feedstocks were used to estimate yields, process costs, and GHG emissions of a biorefinery process based on these biomasses. Within the chain options, GHG emissions were overly sensitive to cultivation input, mostly N‐fertilization. This considered, GHG emissions resulted similar across different feedstock with straw/stover (averaging 13 g CO2eq MJ−1 fuel), sunn hemp (14 g CO2eq MJ−1 fuel), and biomass sorghum (16 g CO2eq MJ−1 fuel). On the other hand, the bioethanol produced from biomass sorghum (608 € Mg−1 of bioethanol) was cheaper compared with straw (632 € Mg−1), sunn hemp (672 € Mg−1), and stover (710 € Mg−1). The bioethanol cost ranged from 0.0017 to 0.020 € MJ−1 fuel depending on the feedstock, with operations and maintenance impacting up to 90% of the final cost. In summary, a single bioethanol plant with an annual capacity of 250,000 Mg of biomass could replace from 5% to 7% of the Emilia‐Romagna's ethanol fuel consumption, depending on the applied sourcing scenario.

Comparative Analysis of Pretreatment Methods for Fruit Waste Valorization in Euglena gracilis Cultivation: Impacts on Biomass, β-1,3-Glucan Production, and Photosynthetic Efficiency.

This study explored the sustainable valorization of fruit waste extracts from sugarcane bagasse (SB), banana peel (BP), and watermelon rind (WR) for Euglena gracilis biomass and β-1,3-glucan production. The extracts were prepared using water extraction (WE), high-temperature and pressure treatment (HTP), and dilute sulfuric acid treatment (DSA). The DSA-treated extracts consistently yielded the best results. E. gracilis cultured in SB-DSA showed the highest cell density with a 2.08-fold increase compared to the commercial HUT medium, followed by BP-DSA (1.35-fold) and WR-DSA (1.70-fold). Photosynthetic pigment production increased significantly, with chlorophyll a yield being highest in SB-DSA (1.90-fold increase). The chlorophyll a/b ratio and total carotenoid content also improved, indicating enhanced light-harvesting capacity and photoprotection. Photosynthetic efficiency, measured by chlorophyll fluorescence, notably improved. The maximum quantum yield of PSII (Fv/Fm) increased by up to 25.88% in SB-DSA, suggesting reduced stress and improved overall photosynthetic health. The potential photochemical efficiency (Fv/F0) showed even greater improvements: up to 40.53% in SB-DSA. Cell morphology analysis revealed larger cell aspect ratios, implying a more active cellular physiological state. β-1,3-glucan yield also increased by 23.99%, 12.92%, and 23.38% in SB-DSA, BP-DSA, and WR-DSA, respectively. This study demonstrates the potential of pretreated fruit waste as a cost-effective and sustainable medium for E. gracilis cultivation, offering the dual benefits of waste valorization and high-value compound production. These findings contribute to the development of more efficient biorefinery processes and align with the circular economy principles in food biotechnology.

New Green Biorefinery Strategies to Valorize Bioactive Fractions from Palmaria palmata.

A biorefinery process was developed to isolate phycobiliproteins, sulfated polysaccharides, and phenolic compounds from Palmaria palmata. The extraction process was carried out in three stages using ultrasound-assisted extraction (UAE) and pressurized liquid extraction (PLE) integrated with different natural deep eutectic solvents (NaDESs). In general, PLE provided higher phycobiliprotein contents than UAE in the first step of the process. In fact, the hydrolysis product of the PLE-NaDES extracts achieved a higher antioxidant capacity than that of the UAE-NaDES extracts. Particularly, glycerol:glucose (2:1) with 50% water in combination with PLE was the most suitable NaDES to recover the highest phycobiliprotein, protein, and sulfated polysaccharide contents from Palmaria palmata in the first and second steps of the biorefinery process. Finally, a PLE-NaDES using choline chloride:glycerol (1:2) with 60% water as the NaDES was employed for the recovery of antioxidant and neuroprotective phenolic compounds from the residue of the second step, obtaining a higher total phenolic content than employing PLE with ethanol/water (70:30, v/v) as the extraction solvent. Moreover, a forced stability study revealed that the NaDESs provided a protective effect compared to the water extracts against the degradation of phycobiliproteins, preserving their color over time. This study contributes to the recovery of high-value components from an undervalued biomarine source through a sustainable biorefinery process.

Lower Energy-Demanding Extraction of Bioactive Triterpene Acids by Microwave as the First Step towards Biorefining Residual Olive Skin.

In the olive oil industry, a pit fraction is collected from olive pomace and split into a clean pit fraction and a residual olive skin-rich fraction, which does not an industrial application. Therefore, in this work, microwave-assisted extraction (MAE) was applied to obtain high-value triterpene acids (maslinic acid and oleanolic acid) from this biomass using the renewable solvent ethanol. The response surface methodology was used to gain a deeper understanding of how the solvent (ethanol-water, 50-100% v/v), time (4-30 min), and temperature (50-120 °C) affect the extraction performance, as well as the energy required for the process. The effect of milling was also studied and the solid-to-liquid ratio was also evaluated, and overall, a good compromise was found at 10% (w/v) using the raw sample (unmilled biomass). The optimised conditions were applied to residual olive skin sourced from various industries, yielding up to 5.1 g/100 g and 2.2 g/100 g dry biomass for maslinic acid and oleanolic acid, respectively. In conclusion, the residual olive skin is a promising natural source of these triterpene acids, which can be extracted using MAE, releasing extracted solids rich in polymeric carbohydrates and lignin that can be valorised under a holistic biorefinery process.

Novel self-pretreatment of biomass by in-situ preparation of acid-assisted carbohydrate-derived DES

Deep eutectic solvents (DES) can greenly and efficiently fractionate biomass, but their utilization efficiency is severely limited by the high ratio of DES required and the wasted hemicelluloses released during the pretreatment. Herein, this work first developed a novel self-pretreatment of biomass by in-situ preparation of acid-assisted carbohydrate-derived DES with the aid of ball milling to facilitate enzymatic hydrolysis. The effect of hydrogen bond acceptor types, water content, acid content, and ball-milling time on enzymatic hydrolysis was studied systematically. Under the optimal condition (tetrabutylammonium chloride (TBAC), 1000 wt% H2O, 100 wt% acids, ball milling for 2 h), the yields of glucose and xylose produced from the pretreated substrates after enzymatic hydrolysis were >99.9 % and 88 %, respectively. Furthermore, the structural integrity of the residual lignin was well-preserved, making it suitable for positional structural characterization and ideal substrates for lignin degradation. Characterization suggested that the hemicelluloses fragments via in-situ acid hydrolysis acted as hydrogen bond donors and combined in situ with TBAC to form DES. This strategy avoided the use of high dosages of DES and the wastage of hemicelluloses, and promoted the sustainability of the entire biorefinery process.

Scalable membrane-assisted ion exchange (MEM-IE) strategy for organic acid purification in biorefinery process

The transition towards a carbon-neutral society necessitates radical approaches in the bio-refinery pipeline, particularly in the production of organic acids. The current downstream process from a dilute fermentation broth is limited by the extensive use of acids and bases, along with heavy reliance on energy-intensive distillation. In this work, we propose an entirely membrane-based process to purify organic acids (e.g., gluconic acid) from a crude solution of catalytic dehydrogenation of glucose. To facilitate downstream purification, we introduce an innovative membrane-assisted ion exchange (MEM-IE) strategy, which is a scalable process that can protonate ionic compounds entirely in the solution phase. Instead of a solid ion exchange resin, a bulky yet soluble acidification agent is used to protonate the target compound, which can be easily separated via a size exclusion membrane. We selected non-toxic poly (4-styrene sulfonic acid) (H-PSS, 75 kDa) as the acidification agent to selectively protonate gluconate ions and to enable facile fractionation. The proposed MEM-IE strategy can overcome the scale-up limitation of traditional solid ion exchange resins and can be applied to many types of ionic compounds. The versatility of the proposed process was also demonstrated on formate and lactate compounds. A techno-economic evaluation using the Verberne cost model showed that the proposed process achieves an 80 % reduction in energy consumption compared to the fermentation-based process, and the return on investment (ROI) of a 330 ton-per-day plant was less than a year. The proposed membrane-based process for the purification of organic acids, particularly the MEM-IE strategy, offers a sustainable and energy-efficient downstream separation platform.

Furfural purification and production from prospective agricultural waste of oil palm empty fruit bunch: Simulation, design and economic assessments

Furfural is potentially produced from lignocellulose waste of biorefinery processes and is widely used as a value-added in various chemical industries. However, the purification of furfural should be conducted to obtain high purity. This work aims to synthesize, design, and optimize the furfural production using some alternative distillation processes by simulation using Super Pro and ASPEN software. The pretreatment process of producing crude furfural from empty fruit bunch waste is also evaluated. The production cost of $0.23/kg of crude furfural (5%) was obtained in the preliminary process. In the purification process, the sequenced distillation process was less prospective than the extractive distillation based on the simulation basis and economic evaluation. The extractive distillation using n-butyl chloride performed better than toluene and benzene as the furfural recovery, and the purity was 98.60% and 99.94%, respectively. The payback period (PBP), internal rate return (IRR), and net present value (NPV) also indicated the great performance of the extractive distillation process with values of 1.24 years, 36.04%, and $14,591,500, respectively. Therefore, the simulation, design, and economic evaluation presented promising results that are feasible for plant establishment.

From agricultural waste to value: Integrated chemo and biocatalytic biorefinery processes to produce 2-furoic acid

The integration of biocatalysis in biorefineries can lead to synergies for raw material valorization. Enzymes must perform efficient and selective reactions when using crude effluents (to avoid costly downstream units). Herein, this is showcased with the synthesis of 2-furoic acid, starting from rice husk (agricultural waste), via a sequential organic-acid catalyzed pretreatment – to afford xylose and cellulose and lignin –, followed by the microwave-assisted acidic xylose dehydration to furfural, in situ extraction in ethyl acetate, and the final biocatalytic selective oxidation of furfural to 2-furoic acid (2-FA). To validate the concept, a xylose-rich hydrolysate (∼ 15 g xylose L−1) obtained from rice husk (RH) was used, achieving a furfural yield of 70 % in a biphasic system (water – ethyl acetate). The obtained furfural extracted in the ethyl acetate was subsequently oxidized to 2-furoic acid via an organic peroxide reaction mediated by Candida antarctica lipase B (CALB), with an overall yield of 90 %, and, with a yield of 41.72 % based on the initial xylose in biomass. Notably, 20 mg/mL CALB could tolerate up to 400 mM of furfural under optimum conditions of 40 °C, 48 h. The recyclability of the biocatalyst was investigated, enabling an efficient reuse of four consecutive cycles.

Integral fractionation of Arundo donax using biphasic mixtures of solvents derived from biomass: An environmentally friendly approach

Arundo donax, one of the most invasive plants in the world, but also a promising source of lignocellulose materials was employed as a feedstock for a biorefinery process. Water-extracted Arundo donax samples were subjected to one-step biphasic fractionation in catalyzed media containing water and 1-butanol, an environmentally-friendly solvent. The effects of selected operational variables (catalyst concentration, temperature and reaction time) on the measured effects (solid recovery yield and compositions of the solid, aqueous and organic phases resulting from treatments) were assessed using statistical methods. The results allowed a quantitative discussion on aspects regarding the selectivity of component separation (lignin, glucan, and hemicelluloses), the overall recovery of valuable products, and the selection of operational conditions enabling extensive delignification (around to 90 %) and high recovery rates of glucan and hemicellulose-derived sugars (above 80 % and 75 %, respectively). This study provides new insights into biphasic fractionation, highlighting the selective separation of hemicellulose, cellulose and lignin into a single and sustainable process, thereby by enhancing biomass resource while reducing environmental impact.

Conversion of acidified lignin containing sulfur discharged from a biorefinery process into neutralized biochar: Characterization and metal adsorption

The objectives of this study were to produce biochars using sulfur-rich acidified lignin discharged from a biorefinery process and to evaluate their physicochemical properties and Pb adsorption capacity. As the pyrolysis temperature increased, the lignin acidified by the desulfurization process was converted to neutralized biochar (LBC), which exhibited high carbon content and stability. The carbon content of biochar manufactured at a pyrolysis temperature of 600 °C or higher was over 90 % and showed no significant difference, and their surface structures were found to be different, as revealed through XRD and FTIR analyses. The adsorption capacity of Pb by LBC increased with increasing pyrolysis temperature, and their adsorption capacity was well described by the pseudo-second-order model and the Langmuir isotherm adsorption model. In particular, the internal diffusion effect on the adsorption capacity of Pb was greater for LBC900 than for LBC600. In complex heavy metal solutions, LBC selectively exhibited high affinity for Pb, while the adsorption capacity of other metals was significantly reduced. The adsorption mechanism of Pb by LBC was verified through various analytical methods, and these results demonstrated that the adsorption of Pb by LBC was influenced by functional groups existing on the surface and inside of LBC and by some cation exchange.

Integrating biochar production in biorefineries: towards a sustainable future and circular economy

AbstractBiochar, a carbon‐rich material derived from organic biomass under low‐O2 conditions, has gained importance due to its role in mitigating climate change by sequestering carbon. It can be used as an alternative energy source and has applications in nutrient cycling, improving soil properties, and removing heavy metals and organic pollutants, thus contributing to sustainable agriculture and environmental remediation. In the face of alarming climate change, rising energy demand, and increasing pollution, the integration of biochar production into biorefineries is an important strategy to promote a sustainable and circular economy. Adopting a holistic approach to biomass utilization by developing strategies to maximize biochar production along with the production of other value‐added products while improving its quality can increase biorefineries' overall sustainability and efficiency. Fine‐tuning the biorefinery process from feedstock selection to co‐production, optimizing pyrolysis conditions, and integrating it with other technologies can help to achieve this goal while generating zero waste and diversified revenues. With the biochar market growing exponentially, further research into the long‐term impact of biochar on carbon sequestration and its application in the environment is the next step.

Study of Purified Cellulosic Pulp and Lignin Produced by Wheat Straw Biorefinery

With the world population rising, wheat straw production is expected to reach 687–740 million tons per year by 2050. Its frequent application as a fuel source leads to air, water, and soil pollution. Limited literature exists on methods for separating components of residual wheat straw. Optimal conditions for organosolv pulping of hydrolyzed wheat straw include 3% FeCl3·6H2O as a catalyst, a biomass-to-solvent ratio of 1:15 (m/v), and 50% ethanol:water as cooking liquor at 200 °C for 30 min. Desilication conditions involve extraction with 7.5% Na2CO3 at a biomass-to-solvent ratio of 1:20 (m/v) treated at 115 °C for 60 min. Lignin from hydrolyzed wheat straw showed similar properties to organosolv lignin from untreated straw, with minimal lignin alteration during hydrolysis. Hydrolysis significantly degraded cellulose. A 41% lignin recovery rate with 95% purity was achieved from pre-extracted hydrolyzed straw. Recovered cellulose after silica removal had 2% ash and 87% purity. The innovation of this process lies in the development of a comprehensive, sustainable, efficient, and economically viable biorefinery process that efficiently separates key components of wheat straw, i.e., xylose, lignin, cellulose, and silica, while addressing environmental pollution associated with its traditional use as fuel.

Switchable transformation of biomass-derived furfural to furfuryl alcohol and isopropyl furfuryl ether over a zirconium-based bifunctional catalyst

Selectively converting biomass-derived furfural (FF) to furfuryl alcohol (FFA) and isopropyl furfuryl ether (IPFE) via the same catalytic system is an important strategy for the production of high-value chemicals and fuels. However, this strategy still faces a great challenge because the formation of FFA and IPFE requires different catalyst types and reaction conditions. Hence, developing a compatible catalytic system is extremely necessary. In this work, we designed a high-efficiency zirconium-based bifunctional catalyst (Zr-HC-SO3H), simultaneously containing Lewis acid-base sites (Zr4+–O2−) and Brønsted acid sites (–SO3H), which were mainly responsible for the Meerwein-Ponndorf-Verley reduction reaction of FF and further etherification reaction of FFA, respectively. By controlling reaction conditions, the action orders and catalytic activities of Zr4+–O2− and –SO3H could be accurately regulated. Thus, Zr-HC-SO3H showed excellent catalytic performance for the switchable transformation of FF, leading to 98.9 % FFA yield at 120 °C for 4 h and 95.1 % IPFE yield at 170 °C for 12 h in isopropanol (iPrOH). Additionally, the analysis results of reaction pathways indicated that the etherification of FFA was much more difficult than the reduction of FF over Zr-HC-SO3H in iPrOH, so IPFE was only formed under the harsher reaction conditions. More significantly, Zr-HC-SO3H also catalyzed the switchable transformation of many other carbonyl compounds and demonstrated satisfactory catalytic universality in iPrOH. In conclusion, this work offered some momentous clues for the development of multipurpose catalytic systems and the controllable synthesis of valuable products in the biorefinery process.

Green biorefinery of walnut husk: Phenolic extraction and ethanol production

Microwave and ultrasound techniques were utilized on walnut green husk (WGH) to extract valuable phenolic compounds and enhance the residual biomass's susceptibility to hydrolysis for subsequent ethanol production. The aim was to optimize process variables in order to achieve an integrated biorefinery with the zero-waste-base standpoint. For microwave-assisted extraction (MAE), four-time levels (0.5, 1.0, 2.0, and 5 min) and power settings (300, 450, 600, and 800 W) were tested. Ultrasound-assisted extraction (UAE) was conducted at a frequency of 28 kHz and power of 100 W over varying time intervals (2, 6, 10, 14, 18, and 22 min). Generally, higher power settings and longer extraction times produced higher contents. Specifically, the maximum total phenolic content (TPC) (220.13 mg GAE/g-DW), total flavonoid content (TFC) (63.21 mg catechin/g-DW), and DPPH scavenging activity (86.13 %) were achieved using the highest power and longest extraction time for MAE. Similarly, the longest UAE time resulted in the highest TPC (214.32 mg GAE/g-DW), highest TFC (58.44 mg catechin/g-DW), and DPPH scavenging activity (76.15 %). Moreover, increased microwave power and longer extraction times favored glucose and ethanol yields, with maximum yields of 55.30 % and 36.67 %, respectively, obtained at 800 W for 5 min. For UAE, the highest glucose and ethanol yields (52.33 % and 34.16 %, respectively) were obtained at 22 min. Conversely, lower extraction times and power settings for microwave, as well as shorter ultrasound times, were beneficial for lignin removal. The application of MAE and UAE in the WGH biorefinery process enhanced the extraction of phenolics and improved biomass hydrolysis, leading to more efficient, sustainable, and economically viable production of biofuels and bioproducts.

Innovative sustainable bioreactor-in-a-granule formulation of Trichoderma asperelloides

The advancement of fungal biocontrol agents depends on replacing cereal grains with low-cost agro-industrial byproducts for their economical mass production and development of stable formulations. We propose an innovative approach to develop a rice flour-based formulation of the beneficial biocontrol agent Trichoderma asperelloides CMAA1584 designed to simulate a micro-bioreactor within the concept of full biorefinery process, affording in situ conidiation, extended shelf-life, and effective control of Sclerotinia sclerotiorum, a devastating pathogen of several dicot agricultural crops worldwide. Rice flour is an inexpensive and underexplored byproduct derived from broken rice after milling, capable of sustaining high yields of conidial production through our optimized fermentation-formulation route. Conidial yield was mainly influenced by nitrogen content (0.1% w/w) added to the rice meal coupled with the fermentor type. Hydrolyzed yeast was the best nitrogen source yielding 2.6 × 109 colony-forming units (CFU)/g within 14 days. Subsequently, GControl, GLecithin, GBreak-Thru, GBentonite, and GOrganic compost+Break-Thru formulations were obtained by extrusion followed by air-drying and further assessed for their potential to induce secondary sporulation in situ, storage stability, and efficacy against Sclerotinia. GControl, GBreak-Thru, GBentonite, and GOrganic compost+Break-Thru stood out with the highest number of CFU after sporulation upon re-hydration on water-agar medium. Shelf-life of formulations GControl and GBentonite remained consistent for > 3 months at ambient temperature, while in GBentonite and GOrganic compost+Break-Thru formulations remained viable for 24 months during refrigerated storage. Formulations exhibited similar efficacy in suppressing the myceliogenic germination of Sclerotinia irrespective of their concentration tested (5 × 104 to 5 × 106 CFU/g of soil), resulting in 79.2 to 93.7% relative inhibition. Noteworthily, all 24-month-old formulations kept under cold storage successfully suppressed sclerotia. This work provides an environmentally friendly bioprocess method using rice flour as the main feedstock to develop waste-free granular formulations of Trichoderma conidia that are effective in suppressing Sclerotinia while also improving biopesticide shelf-life.Key points• Innovative “bioreactor-in-a-granule” system for T. asperelloides is devised.• Dry granules of aerial conidia remain highly viable for 24 months at 4 °C.• Effective control of white-mold sclerotia via soil application of Trichoderma-based granules.

The comparative techno-economic and life cycle assessment for multi-product biorefinery based on microwave and conventional hydrothermal biomass pretreatment

Microwave as an efficient and clean energy, is easy integrated with DES pretreatment and biorefinery process to achieve process intensification for cleaner production and sustainable development. However, there are worries about its economic and environmental feasibility for application in biorefinery plant. This work conducted the techno-economic (TEA) and life cycle assessment (LCA) of the entire biorefinery process based on DES pretreatment by microwave heating (MH) for producing glucose, furfural and lignin from lignocellulose, of which the results were compared with conventional heating (CH). For pretreating equivalent biomass, the total yield of products obtained from MH-assisted process was 8.53% higher than that of CH-assisted process due to microwave intensification effect. From the perspective of cradle-to-gate LCA, the MH-assisted process saved energy demand of 5.82%, reducing the environmental impacts global warming (GW) and fossil resource scarcity (FRS) by 4.85% and 5.69%, respectively, relative to CH-assisted process. The main environmental hotspots of both two processes concentrated on the raw material extraction (RME), followed by product separation and solvent recovery (PSSR) stages. Based on economic evaluation, the specific values of TAC regarding one-ton product for MH- and CH-assisted processes were 3194.35 and 3400.37 $/(y⋅t), respectively. Therefore, the MH-assisted pretreatment possessed certain environmental and economic advantages due to product increasement, energy consumption reduction in the DES pretreatment, and burden reduction for subsequent enzyme hydrolysis. Compared to the single-product biorefinery, the multi-product biorefinery strategy was more sustainable and could maximize the advantages of microwave intensification. However, some issues about the design of microwave reactors and temperature monitoring must be considered to pursue scale-up biorefinery plant.

Fully biobased unsymmetric bisphenols from condensation of lignin-derived monophenols for non-isocyanate polyurethane synthesis

Transforming renewable biomass and CO2 to the high value-added non-isocyanate polyurethanes (NIPUs) was of great significance to the development of sustainable chemistry. Herein, a series of unsymmetric bio-based bisphenols featured with chalcone structure were designed and synthesized by Claisen-Schmidt condensation of lignin-derived monophenols (vanillin and syringaldehyde) and plant methyl ketones (zingiberone, raspberry ketone, and piceol), these phenols and ketones are value-added chemicals from biorefinery process of biofuels. The unsymmetric bio-based bisphenols were consequently transformed into bis-epoxides, bis(cyclic carbonate)s, and finally polyhydroxyurethanes (PHUs). With eco-friendly proline as the catalyst, bio-based bisphenols were prepared in excellent yields (76% − 95%). More than 90% isolated yields of bis(cyclic carbonate)s were obtained from bis-epoxides. All of the bis(cyclic carbonate)s were cured with long-chain amine, i.e. PriamineTM 1074, and the result PHUs, a kind of NIPUs, have thermal stability comparable to bisphenols A-based network according to DSC and TGA. The attempts to one-pot-two-step synthesis of PHUs also exhibited better thermal properties, which bis-epoxides directly conducted successively with carbon dioxide and 1,6-hexamethylenediamine. The bio-based bisphenols appeared to be a promising substitute to bisphenols-A with the aim at synthesizing environmentally friendly PHUs. Therefore, this study provided a valuable route in utilization of carbon dioxide and functional aromatics from fuel process into fully biobased polymeric materials.

Bio-physical pre-treatments in anaerobic digestion of organic fraction of municipal solid waste to optimize biogas production and digestate quality for agricultural use

This study optimized the anaerobic digestion (AD) of separated collected organic fractions of municipal solid waste (OFMSW) to produce energy and digestate as biofertilizer. Due to OFMSW’s partial recalcitrance to degradation, enzymatic (UPP2, MCPS, USC4, USE2, A. niger) and physical (mechanical blending, heating, hydrodynamic cavitation) pre-treatments were tested. Experimental and modeling approaches were used to compare AD performance regarding energy sustainability and digestate quality. Digestate was separated into solid and liquid fractions, and then chemically and physically characterized by investigating the nutrient release mechanisms. Principal Component Analysis was applied, equally weighing energy and digestate productions. Unlike previous studies focusing only on biogas, this study evaluated the effects of pre-treatments on both biogas and digestate production, viewing AD as a biorefinery process for urban waste valorization. Results showed that all pre-treatments were energetically sustainable, but enzymatic pre-treatments yielded digestates richer in nutrients (increase of 80% N, 200% P and 150% K as compared to OFMSW) and with greater organic matter degradation compared to physical pre-treatments. The liquid fraction of digestate from enzymatic pre-treatments had higher nutrient concentrations, while those from physical pre-treatments had more balanced nutrient content, making them more suitable for fertigation.

An integrated biorefinery of Madhuca indica for co-production of biodiesel, bio-oil, and biochar: Towards a sustainable circular bioeconomy

The advancement of non-waste biorefinery technology has proved beneficial in effectively using waste biomass resources. The potential of various biorefinery designs to transform biomass into a range of commercially viable products and bioenergies has piqued attention worldwide among the several scenarios proposed to commercialize biofuels. This paper describes the biorefinery of Madhuca indica (M. indica) seeds to generate biochar, bio-oil, and biodiesel. Pyrolization was used on the de-oiled cake to produce charcoal and bio-oil. The M. indica seed's biochar was utilized as a useful supporting particle to immobilize the enzyme. Through transesterification, the immobilized enzyme transformed the oil extracted from the seed into biodiesel. Using an optimum methanol-to-oil ratio of 7.5:1, 3 % (w/w) of catalyst, and 16 % (v/v) of water content, the method yielded a maximum fatty acid methyl ester (FAME) conversion of 93.4 %. Diesel and 20 % biodiesel have been assessed in terms of performance and emissions analysis. Comparing a 20 % blend of biodiesel to commercial diesel at full load, the emissions of carbon monoxide (CO) were reduced by 21.2 %, hydrocarbon (HC) emissions by 18.02 %, and nitric oxide (NO) emissions by 4.33 %. In addition, the capital flow of the suggested biorefinery was assessed using a techno-economic analysis. The biorefinery process payback period for the biodiesel, bio-oil, and charcoal made from M. indica was determined to be 3.1358 years using the Aspen Plus Economic Analyzer. Techno-economic studies reveal that the biorefinery process is highly lucrative and practical. The current study therefore shows methods to use the Madhuca indica seed biorefinery to produce sustainable energy and byproducts with no net emissions of carbon.