Multiple Value-added Products Research Articles

Sugarcane bagasse valorization through integrated process for single cell oil, sulfonated carbon-based catalyst and biodiesel co-production

This study demonstrates the conversion of sugarcane bagasse (SB) into single cell oil (SCO), sulfonated carbon-based catalyst and biodiesel; this process aligns with waste-to-energy and circular bioeconomy concepts. SB was treated with dilute sulfuric acid to achieve SB hydrolysate (SBH) and SB solid residue (SBS). Candida tropicalis KKU-NP1, a newly isolated yeast, accumulated SCO content of 26.5 % from undetoxified SBH medium. A novel sulfonated carbon-based catalyst (SBS@SC) was generated from SBS by a one-step hydrothermal sulfonation process. It showed significant catalytic activity for the conversion of SCO-rich KKU-NP1 wet cell into biodiesel (FAME) under direct transesterification optimal conditions, with a FAME conversion yield of 90.1 %. Based on FAME profile, most of the estimated physicochemical and fuel properties of FAME were within the limits of ASTMD6751 and EN 14214 for biodiesel standards. For integrated process the final production of about 12.0 g SCO, 606.3 g SBS@SC catalyst and 10.8 g biodiesel from 1000 g raw SB were achieved.This study highlights the utilization of SB as a low-cost feedstock for producing multiple value-added products, emphasizing the advantages of waste utilization by integrated biorefinery concept, yielding practically no waste by-products over the whole production process.

Effect of Nb as dopant of hydrotalcite catalysts during the ethanol condensation to optimize n-Butanol production

The present study optimizes Cu-supported catalysts on hydrotalcite for the synthesis of n-butanol whose interest is in its use as biofuel, due to its superior performance in comparison with other short-chain alcohols. The catalytic performance was improved by adding Nb to the catalytic formulation. In this way, several Cu-Nb catalysts supported on hydrotalcites (Mg/Al) with different Nb loadings were synthesized by incipient wetness impregnation and characterized by H2−temperature-programmed reduction, X-ray diffraction, N2 physisorption, CO2− and NH3−thermo-programmed desorption and X-ray photoelectron spectroscopy. It was shown that the incorporation of Nb promoted a suitable balance between the acid-basic and redox sites, modulating the Cu0/Cu+ dehydrogenation/hydrogenation properties for the n-BuOH production. The synthesis of multiple value-added products (n-BuOH, acetaldehyde, ethyl acetate, and 1-hexanol) was achieved in both the liquid− (at 180 ºC) and gas−phase (150−350 ºC), where it was demonstrated that both the n-BuOH selectivity and ethanol conversion improved with the Nb addition. The performance of the catalysts under time on stream and their recycling is also described.

Construction of Ag─Co(OH)2 Tandem Heterogeneous Electrocatalyst Induced Aldehyde Oxidation and the Co-Activation of Reactants for Biomass Effective and Multi-Selective Upgrading.

The electrocatalytic oxidation of 5-hydroxymethylfurfural (HMF) provides a feasible way for utilization of biomass resources. However, how to regulate the selective synthesis of multiple value-added products is still a great challenge. The cobalt-based compound is a promising catalyst due to its direct and indirect oxidation properties, but its weak adsorption capacity restricts its further development. Herein, by constructing Ag─Co(OH)2 heterogeneous catalyst, the efficient and selective synthesis of 5-hydroxymethyl-2-furanoic acid (HMFCA) and 2,5-furan dicarboxylic acid (FDCA) at different potential ranges are realized. Based on various physical characterizations, electrochemical measurements, and density functional theory calculations, it is proved that the addition of Ag can effectively promote the oxidation of aldehyde group to a carboxyl group, and then generate HMFCA at low potential. Moreover, the introduction of Ag can activate cobalt-based compounds, thus strengthening the adsorption of organic molecules and OH- species, and promoting the formation of FDCA. This work achieves the selective synthesis of two value-added chemicals by one tandem catalyst and deeply analyzes the adsorption enhancement mechanism of the catalyst, which provides a powerful guidance for the development of efficient heterogeneous catalysts.

Valorization of straw biomass into lignin bio-ink, bacterial cellulose and activated nanocarbon through the trade-off alkali-catalyzed glycerol organosolv biorefinery

Integrated lignocellulosic biorefinery that transforms low-value lignocellulose into multiple value-added products is crucial for a low-carbon sustainable development. Herein, a one-pot alkali-catalyzed glycerol organosolv (ALGO) pretreatment-based integrated biorefinery process to directionally produce lignin bio-inks, bacterial celluloses (BCs), and activated nanocarbons (ANCs) was proposed. ALGO pretreatment could modify the structure of dissolved lignins by glycerolysis. The extracted lignin fragments with high-purity (>90 %), uniform with low molecular weight (2500–4000 of Mw), and abundant hydrophilic aliphatic –OH were promising candidates in 3D-printable inks preparation. The glycerolysis reaction during ALGO process also enabled pretreated substrates toward high hydrolyzability and protected pretreatment liquor from generating fermentable inhibitors, making the solid fractions more liable for enzymatic deconstruction and microbial fermentation. Without any detoxification treatments, hydrolysates from ALGO pretreated substrates were used directly as carbon sources for BCs production, resulting in the BC yields were 56 % higher than that of the commercial glucose. The enzymatic hydrolysis residue and BC fermentation waste liquid were synthesized into ANCs via a facile carbonization process, which could further increase the value of ALGO biorefinery. Calculations showed that this ALGO integrated strategy rendered the conversion of ∼75 % lignins in pretreatment liquor to bio-inks and nearly 100 % solid fractions to BCs and ANCs. Unlike the conventional “lignin-first” route to obtain high-purity cellulose by sacrificing the value-adding conversion ability of by-products, the designed technical route in this work achieved a good trade-off between fractionation ability and subsequent conversion potential, inspiring further exploration of the technical correlation between biomass fractionation and bioproduct processing.

Cascading utilization of residual microalgal biomass: Sustainable strategies for energy, environmental and value-added product applications

Residual microalgal biomass, a byproduct of various microalgae-based processes, represents an abundant and underutilized resource with significant potential for sustainable energy production, environmental applications, and bioproduct development. The cascading approach seeks to maximize resource efficiency and minimize waste by utilizing residual microalgal biomass in a stepwise manner to produce multiple value-added products. This review presents the current research status of residual microalgal biomass applications, focusing on energy, environmental, and bioproduct sectors. It highlights the challenges and complexities associated with cascading utilization of residual microalgal biomass and proposes strategies for managing uncertainty, optimizing the process and introduces a model exemplifying the practical application of this approach. The review aims to provide a comprehensive understanding of the potential of residual microalgal biomass as a valuable resource and to encourage further research in this field to promote a sustainable and circular bioeconomy.

Using the Aqueous Phase Produced from Hydrothermal Carbonization Process of Brown Seaweed to Improve the Growth of Phaseolus vulgaris.

Seaweeds are considered a biomass for third-generation biofuel, and hydrothermal carbonization (HTC) is a valuable process for efficiently disposing of the excess of macroalgae biomass for conversion into multiple value-added products. However, the HTC process produces a liquid phase to be disposed of. The present study aims to investigate the effects of seed-priming treatment with three HTC-discarded liquid phases (namely AHL180, AHL240, and AHL300), obtained from different experimental procedures, on seed germination and plant growth and productivity of Phaseolus vulgaris L. To disentangle the osmotic effects from the use of AHL, isotonic solutions of polyethylene glycol (PEG) 6000 have also been tested. Seed germination was not affected by AHL seed-priming treatment. In contrast, PEG-treated samples showed significantly lower seed germination success. AHL-treated samples showed changes in plant biomass: higher shoot biomass was recorded especially in AHL180 samples. Conversely, AHL240 and AHL300 samples showed higher root biomass. The higher plant biomass values recorded in AHL-treated samples were the consequence of higher values of photosynthesis rate and water use efficiency, which, in turn, were related to higher stomatal density. Recorded data strongly support the hypothesis of the AHL solution reuse in agriculture in the framework of resource management and circular green economy.

Harnessing the Capabilities of Microorganisms for the Valorisation of Coal Fly Ash Waste through Biometallurgy

Coal fly ash (CFA) is a highly versatile raw material that has the potential to yield multiple value-added products, including cenospheres, zeolites, carbon nanotubes, and fertiliser substrates. Despite its versatility, a majority of these components are often overlooked, and CFA is primarily used for construction. Conventional processing methods of CFA are known to pose significant environmental challenges, including the leaching of hazardous materials, emission of toxic gases, and the high energy consumption needed to extract the value-added components. Herein, we explore the potential of biometallurgical approaches as an eco-friendly alternative to conventional processing methods for the comprehensive utilisation of CFA. Our focus is on the application of different microorganisms to CFA, the domestication of microorganisms, preprocessing of CFA to facilitate effective biometallurgical processes, the use of bioreactors, and synthesis of nano silica particles. We also propose a novel method for extracting the value-added components from CFA using a preprocessing technique (i.e., washing cycle), combined with multiple interactions with biometallurgical processes. Adopting this approach, we not only enhance environmental stewardship but also improve the circular economic aspects of multi-component utilisation, while providing valuable insights for the development of sustainable techniques for utilising CFA.

Novel zero waste tactics for commercial vegetables – recent advances

Abstract Commercial vegetables include tomatoes, potatoes, onions, and eggplant due to their surplus production, availability, and affordability. The valorisation of the massive wastage of commercial vegetables and providing a long-term solution has been challenging. The review addresses the implications of biowastes on the environment and fosters the recent investigations into valorising commercial vegetable waste to develop multiple value-added products. It discussed the outcomes of the multiple technologies, majorly on green chemistry extraction, while outlining other methods such as fermentation, enzymatic treatments, 3D printing foods, high-pressure homogenisation, microencapsulation, bio-absorption method, and pyrolysis for their respective vegetable wastes. Agri-residues can be a valuable source for formulating functional ingredients, natural additives, biodiesel, dyes, and animal feed. This comprehensive review proposes a strategy to upcycle low-cost biowaste to boost the economic and ecological benefits. The current review captures the interests and great collaborations between researchers, industrialists, policymakers, waste management bodies, and eco-activists.

Algal biorefinery culminating multiple value-added products: recent advances, emerging trends, opportunities, and challenges.

Algal biorefinery is rising as a prominent solution to economically fulfill the escalating global requirement for nutrition, feed, fuel, and medicines. In recent years,scientific productiveness associated with microalgae-based studies has elaborated in multiplied aspects, while translation to the commercial level continues to be missing. The present microalgal biorefinery has a challenge in long-term viability due to escalated market price of algal-mediated biofuels and bioproducts. Advancements are required in a few aspects like improvement in algae processing, energy investment, and cost analysis of microalgae biorefinery. Therefore, it is essential to recognize the modern work by understanding the knowledge gaps and hotspots driving business scale up.The microalgae biorefinery integrated with energy-based products, bioactive and green compounds, focusing on a circular bioeconomy, is urgently needed. A detailed investigation of techno-economic analysis (TEA) and life cycle assessment (LCA) is important to increase the market value of algal products. This review discusses the valorization of algal biomass for the value-added application that holds a sustainable approach and cost-competitive algal biorefinery. The current industries, policies, technology transfer trends, challenges, and future economic outlook are discussed. This study is an overview through scientometric investigation attempt to describe the research development contributing to this rising field.

Characterization of pellets produced from extracted sawdust: Effect of cooling conditions and binder addition on composition, mechanical and thermochemical properties

Hot-water extraction (HWE) is a biomass processing method that offers an excellent possibility to generate multiple value-added products. In this study, the pellets were produced from the original spruce sawdust and the sawdust after HWE. Two different arrangements to separate the extracted sawdust from the liquid phase (extract) were applied, namely a rapid solid-liquid separation at high temperature and a slow cooling of extracted sawdust along with the extract. Furthermore, the extracted sawdust was also used several times as an adsorbent to purify the extract from the HWE. The effect of binders (kraft lignin and corn starch) on the pellet properties was also evaluated. Fuel properties, mechanical characteristics and chemical composition of produced pellets were analyzed. The HWE improves the mechanical and energy properties by increasing the pellet's length (2–9% increase), particle and energy density (24% and 31% increase correspondingly) in comparison with the untreated sawdust pellets. Additionally, the pellets from the treated sawdust indicated reduced water absorption capacity and improved strength and durability characteristics compared to the untreated ones. The HWE modifies the lignocellulosic matrix of feedstock resulting in more significant modifications than in the case of binder added to the untreated sawdust. The method of residual sawdust separation from the extract had a pronounced effect on the pellet's characteristics, namely a slow cooling of extracted sawdust in mixture with liquid fraction resulted in a smaller amount of hemicelluloses and monosaccharides in the sawdust and more intensive release (up to 70%) of ash forming elements to the liquid phase.

Enhanced biodiesel and β-carotene production in Rhodotorula pacifica INDKK using sugarcane bagasse and molasses by an integrated biorefinery framework

Dependency on fossil fuels raises an economic and ecological concern that has urged to look for alternative sources of energy. Bio-refinery concept is one of the alternate frameworks for the biomass conversion into biofuel and other value-added by-products. The present work illustrates importance of an oleaginous yeast Rhodotorula pacifica INDKK in an integrated bio-refinery field by utilizing renewable sugars generated from lignocellulosic biomass. The maximum 11.8 g/L lipid titer, 210.4 mg/L β-carotene and 7.1 g animal feed were produced by R. pacifica INDKK in bioreactor containing 5% (v/v) molasses supplemented with enzymatically hydrolyzed and alkali-pretreated sugarcane bagasse hydrolysate (35% v/v). Furthermore, xylooligosaccharides (20.6 g/L), a beneficial prebiotics were also produced from the hemicellulosic fraction separated after alkali pretreatment of bagasse. This novel concept of integrated yeast bio-refinery for concomitant production of biodiesel and multiple value-added products with minimum waste generation is proposed as a sustainable and profitable process.

Co-production of hydrochar, levulinic acid and value-added chemicals by microwave-assisted hydrothermal carbonization of seaweed

Seaweed is considered a third-generation biomass for transport biofuel production with great potential for bioenergy and biorefinery applications. Microwave-assisted hydrothermal carbonization (HTC) offers a conversion route for seaweed valorization to multiple value-added products. However, the HTC products (such as hydrochar and process liquor) are highly dependent on feedstock properties and HTC conditions. This study investigated the valorization of Laminaria digitata to a range of products (primarily including hydrochar, levulinic acid and 5-hydroxymethylfurfural) through microwave-assisted HTC at a range of low temperatures (160, 180 and 200 °C) and levels of dilute acid addition (1, 2 and 4% H2SO4 concentration). The work suggests an optimized process at a temperature of 200 °C with 4% H2SO4, with levulinic acid and 5-hydroxymethylfurfural in the process liquor achieved the highest yields of 12.5% (12.5 g per 100 g dry L. digitata) and 5.8%, respectively. The obtained hydrochar had a higher heating value of 25.5 MJ/kg volatile solids, comparable to lignite coal. At such a condition the total carbon recovery in the produced hydrochar and process liquor accounted for 84% of carbon in the original seaweed. The 200 °C derived hydrochar presented the highest carbon content of 65.4%, but the lowest abundance in oxygen-containing functional groups compared to the hydrochars obtained under other conditions (160 and 180 °C). The economic benefits of the process might be significantly increased if hydrochar was upgraded into activated carbon instead of being used as a solid fuel.

Effect of pretreatment and biomass blending on bio-oil and biochar quality from two-step slow pyrolysis of rice straw

This study investigated biomass blending and water washing to improve product quality from two-step pyrolysis of rice straw. Rice straw (RS) was mixed with groundnut shells (GNS) and wheat straw (WS) in different weight ratios. Blending RS with GNS/WS in a 1:1 ratio increased the total bio-oil yields by 7-9% and reduced the pyrolysis gas and char yields by 5-7% and < 2%, respectively. RS was washed with water separately to examine the effect of removing water-soluble ash elements. The optimum washing duration was 60 min; the ash removal efficiency was then 26%. The bio-oil yields from washed straw increased by 4% over unwashed straw, and pyrolysis gas yields decreased. Combining the washing and blending processes increased the levoglucosan yield by 1.6-2.1 times compared to unwashed RS, and the water content in bio-oil was reduced by ∼ 10%. Moreover, the biochar samples obtained after pyrolysis of washed biomass blends had potential fuel applications owing to low fouling or slagging propensity. They also had possible use in the soil for adsorption of soil contaminants and increasing acidic soil pH, with likely stability of ∼ 1000 years in the ground. These results provide a promising alternative for efficiently converting rice straw to multiple value-added products.

Opportunities Surrounding the Use of Sargassum Biomass as Precursor of Biogas, Bioethanol, and Biodiesel Production

Climate change (along with other factors) has caused an increase in the proliferation of brown algal mats floating freely along the Atlantic Ocean since 2011. These brown algae mats are composed of sea plants from the Sargassum genus. The gargantuan agglomeration of biomass flows alongside currents and lands in beaches belonging to the Eastern coasts of the Mexican Caribbean and several other countries in the region. These events, dubbed golden tides, harm the local economy and environment. Current elimination approaches involve the mechanical harvesting of the Sargassum and ultimate landfill disposal. However, explorations into the commercial application of other brown algae have elucidated the potential of Sargassum as a feedstock for valorization. This review informs the trends, challenges, and opportunities presented by the coastal invasion of this biomass. Primarily, the potential use of this material is as a precursor in biorefineries where multiple value-added products are generated concurrent with the ultimate production of biofuels.

Retrofitting analysis of a biorefinery: Integration of 1st and 2nd generation ethanol through organosolv pretreatment of oat husks and fungal cultivation

This study was dedicated to techno-economic analysis of an integrated 1st and 2nd generation biorefinery, where the organosolv pretreated oat husk and thin stillage is valorized through filamentous fungi and baker yeast. By this strategy, process economy can benefit from multiple value-added products including lignin (80% purity), and protein-rich biomass as feed/food ingredients. Ethanol recovery of organosolv pretreatment benefits the already existing equipment in 1st generation ethanol plant. The best results shows that the integration of 10 tons/h oat husk into a process using 18.8 tons/h grains results in increasing ethanol production from 5.2 to 7.5 tons/h, in addition to 1.6 tons/h lignin (80% purity) and 7.6 tons/h fungal biomass. Integrated process is beneficial not only for 2nd but also for 1st generation ethanol production. Selling the fungal biomass as feed and food increased the net present value (NPV) in comparison to conventional ethanol plant by 71% and 7.9-fold, respectively.

Techno-economic analysis of a grape pomace biorefinery: Production of seed oil, polyphenols, and biochar

Processing grape pomace (GP), a major waste from the wine industry, into multiple value-added products based on the biorefinery concept has a potential to reduce waste disposal and promote a sustainable bioeconomy. However, its economic feasibility at a commercial scale remains unknown. The present study aims to evaluate the economics of a biorefinery process of GP, by performing comparative techno-economic analysis of three processing scenarios: (1) a whole biorefinery process that fully utilizes GP biomass and produces grape seed oil, polyphenols, and biochar (GSO+GSKP+GB), (2) a process that produces grape seed oil and polyphenols (GSO+GSKP), and (3) a process that produces only grape seed oil (GSO). A plant capacity of about 33,000 metric tons/year was considered in the analysis. Among the three scenarios, the whole biorefinery process (GSO+GSKP+GB) showed the highest economic performance with the net present value (NPV), internal rate of return (IRR), and payback period of 111.7 million US-$, 34.3%, and 2.5 years, respectively, due to the diverse revenues and minimized waste disposal cost. The GSO plant showed the lowest economic performance with a negative NPV. Sensitivity analysis revealed that plant capacity, polyphenol price, polyphenol concentration (percentage) in grape pomace, and biochar price had dominating influences on the economic performance of the biorefinery process.

Production of levulinic acid and biocarbon electrode material from corn stover through an integrated biorefinery process

To overcome the inefficient biomass conversion, waste generation, and lack of co-production in biorefineries, an integrated process was proposed for the conversion of corn stover into levulinic acid and biocarbon electrode material. Corn stover was pretreated through hydrothermal process using 0.45 wt% K2CO3 which removed 76 wt% lignin and 85 wt% xylan while preserving 83 wt% glucan. This was followed by acid hydrolysis to produce levulinic acid at varying H2SO4 concentrations and reaction time in a batch reactor at 190 °C. At a reaction time of 5 min in 2 wt% H2SO4, 35.8 wt% and 30 wt% glucan in raw and pretreated corn stover was converted to levulinic acid, respectively. The residue from acid hydrolysis was converted into biocarbon for supercapacitor electrodes via a two-step thermal activation process which showed a specific capacitance of 120 F g−1. The proposed integrated biorefinery concept provides multiple value-added products for a greater financial and environmental sustainability.

Investigation of alkaline hydrogen peroxide pretreatment to enhance enzymatic hydrolysis and phenolic compounds of oil palm trunk.

Alkaline hydrogen peroxide (AHP) as a pretreatment effectively enhances the increasing enzymatic digestibility of oil palm trunk (OPT) for conversion to biofuels and bioproducts in the biorefinery processes. The effect of hydrogen peroxide concentration (1-5%), temperature (50-90°C), and time (30-90min) were studied to find out the optimum condition for the removal of lignin. The optimum condition attained at 70°C, 30min, and 3% H2O2 g /g of biomass not only increased the cellulose content from 38.67% in raw material to 73.96% but also removed lignin and hemicellulose up to 50% and 57.12%, respectively. The AHP-treated fibers subjected to enzyme hydrolysis showed significant improvement in glucose concentration that increased from 11.77 (± 0.84) g/L (raw material) to 46.15 (± 0.32) g/L with 59.82% enzyme digestibility at 96h. Scanning electron microscopy (SEM) and Fourier transformation infrared (FT-IR) were employed to analyze the morphology and structural changes of untreated and AHP-treated fibers. SEM results showed disruption of the intact OPT structure resulting in increase of enzyme accessibility to cellulose. The FT-IR identified changes in peaks which indicated structural transformation and dissolution of both lignin and hemicellulose molecules caused by AHP treatment. The black liquor obtained from AHP treatment contained about 5.13mg gallic acid equivalent (GAE)/g of dry sample of total phenolic content (TPC) and an antioxidant activity of 59.80% and 65.51% inhibitions of DPPH and ABTS assays, respectively. Hence, it is a sustainable approach to utilize waste for the recovery of multiple value-added products during pretreatment process.

An integrated valorization of industrial waste of eggplant: Simultaneous recovery of pectin, phenolics and sequential production of pullulan

Based on a bio-refinery concept, the valorization of eggplant peel wastes (EPW) in the production of multiple value-added products was aimed. The acid-free extraction process was applied in the simultaneous recovery of pectin and phenolic compounds. The extraction variables were optimized by response surface methodology using a Box-Behnken design and the maximum yield of pectin (26.1%) and phenolic compounds (20.2%) was obtained in the extraction temperature of 90 °C, time of 90 min and liquid/solid ratio of 40 mL/g. After recovery of pectin and phenolic compounds from EPW, the solid leftovers were enzymatic hydrolyzed and the hydrolysates were used as a carbon source in the microbial production of pullulan by Aureobasidium pullulans. The produced pectin and pullulan were characterized through the chemical and structural features. The results of FT-IR and H-NMR analysis approved the predominant presence of these two polysaccharides in the isolated samples. On the other hand, the antioxidant activity of the recovered phenolic compounds extract was evaluated by DPPH and ABTS radical scavenging activity and reducing power assay.

Facile and cost-efficient indirect carbonation of blast furnace slag with multiple high value-added products through a completely wet process

Mineral carbonation of blast furnace slag (BFS) has been proposed as a comprehensive method for carbon capture and storage and utilization of the industrial solid waste. However, the challenge for this technology to be applied practically is how to reduce the cost of process. A completely wet process combining a CO2-mineralization cell for CO2 capture and membrane electrolysis for recovery of carbonated mother liquor is proposed to simultaneously fix CO2 and produce multiple value-added products. In this process, Ca, Mg, Al, and Si are extracted from BFS with an NH4HSO4 solution prepared from H2SO4 and (NH4)2SO4 with extraction ratios of 97.3%, 98.8%, 96.4%, and 94.3% under optimized conditions, respectively. The extracted Al and Si are then recovered as NH4Al(SO4)2·12H2O (99.59 wt%) and SiO2 (97.70 wt%) with 93% and 98.1% yield, respectively. The CaSO4-rich leaching residue and MgSO4-rich leachate after complete depletion of the residual Al and Si are successively carbonated with an NH4HCO3 solution obtained from a CO2-mineralization cell with total CO2 capacity up to 361 kg-CO2 per tonne BFS. The preliminary economic evaluation shows that the present carbonation route is a cost-efficient method to comprehensively utilize BFS and reduce CO2 emissions.