Biomass Conversion and Biorefinery最新文献

Currently, technologies for hydrogen production are widely studied by characterizing a zero-carbon energy source at the point of end use. Among these, microbial electrolysis cell (MEC) stand out due to their use of microbial biocatalysts and low-cost organic substrates. This study assessed hydrogen production in two-chamber MEC systems using sugarcane vinasse from ethanol biorefineries. The electrogenic microbial community was enriched using a sodium acetate medium, reaching maximum current densities of 5 A m^–3 and 18 A m^–3 at applied voltages of 0.6 V and 0.8 V, respectively. Under continuous mode with acetate, hydrogen production averaged 738 and 1474 µmol H₂ L^− 1 d^− 1, with hydrogen purities of 93% and 97%, respectively. After acclimation to vinasse (5–40% v/v), coupling two MEC modules in series resulted in a 3.6-fold increase in hydrogen production compared with single module operation, achieving a maximum of 5256 µmol H₂ L^− 1 d^− 1. These results demonstrated the feasibility of directly converting vinasse into hydrogen through a bioelectrochemical process and highlight the potential for integrating MEC systems into sugarcane biorefineries for clean energy recovery.

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are a group of emerging contaminants that have increasingly attracted research interests due to their extensive use and pervasive presence in the environment. Biochar has emerged as an inexpensive and environmental-friendly alternative for removing PFAS from water matrices due to its high sorption capacity, simplicity in design and operation, and economic viability. The abundance of biochar feedstocks further enhances the appeal of this method. This article presents a comprehensive review of studies pertaining to PFAS removal from diverse water matrices using biochar, focusing on the following key aspects: (1) efficiencies of removal of PFAS using biochar; (2) elucidation of PFAS removal mechanisms; (3) biochar feedstock and process conditions, and PFAS physico-chemical properties influencing removal mechanisms; (4) influence of water matrix properties including pH, Natural Organic Matter and ion contents, and temperature on PFAS removal efficiency; (5) assessment of reusability of biochar for PFAS treatment; and (6) challenges in scalability and economic feasibility of using biochar. A flow diagram was developed to facilitate the evaluation of PFAS removal efficiency, considering biochar and PFAS physico-chemical properties as well as water matrix constituents. The review addresses current challenges, such as the lack of sufficient research on recently introduced PFAS substitutes, hybrid treatment, biochar design and economically viable, effective regeneration approaches, scaling up and deployment challenges, and environmental and ecosystem implications. Furthermore, this review recommends real-world condition testing for efficiency evaluation. The review emphasizes that the findings reported in the literature should be validated in full-scale experiments. 

Graphical Abstract

A novel heterogeneous nanocatalyst, Carbon nanotube-doped calcium oxide (CNT-CaO) derived from waste eggshells was used for producing biodiesel from high Free Fatty Acid (FFA)Livistona jenkinsianaGriff. oil, a rarely explored plant-based feedstock. Biodiesel synthesis was performed via a two-stage process- acid esterification followed by base-catalysed transesterification. Catalyst characterization was done usingFourier Transform Infrared (FTIR) spectroscopy, Raman spectroscopy, X-ray diffraction (XRD), Field-Emission Scanning Electron Microscopy(FESEM) coupled with Energy-Dispersive X-ray spectroscopy (EDX), Transmission Electron Microscopy (TEM), and Brunauer-Emmett-Teller (BET) analysis. The successful incorporation of CNTs onto CaO increased the surface area from 26.89 m²/g to 40.24 m²/g and pore volume changed from 0.092 cm³/g to 0.080 cm³/g. Process parameters were optimized using Central Composite Design (CCD) under the Response Surface Methodology (RSM) framework, achieving a maximum experimental conversion efficiency of 97.2% at a methanol-to-oil molar ratio (M/O) of 9.12:1, a catalyst concentration of 3.19 wt%, and a reaction time of 3.28 h at 60 °C. Gas chromatography-mass spectrometry (GC-MS) analysis showed that the biodiesel was primarily composed of palmitic (40.19%) and oleic (51.87%) acid methyl esters. The fuel properties met American Society for Testing and Materials (ASTM) D6751 specifications, with a cetane number of 62, oxidative stability of 5.5 h, and cloud and pour points of 11 °C and 5 °C, respectively. The catalyst retained 65.2% activity after seven cycles, indicating good reusability. These findings highlight the potential of CNT-CaO as an effective and sustainable nanocatalyst, and demonstrate the viability of Livistona jenkinsianaGriff.oil as a promising and underexplored feedstock for biodiesel production.

In this work, we have synthesized bamboo stem porous activated carbon/zinc oxide/copper oxide (BSPAC/ZnO/CuO) ternary nanocomposite using hydrothermal method. Subsequently, the synthesized BSPAC/ZnO/CuO ternary nanocomposite, BSPAC, ZnO and CuO NPs were confirmed by FT-IR, powder XRD, Raman, FE-SEM, EDAX with elemental mapping, UV–Vis DRS, HR-TEM, TGA, XPS and BET surface analysis. Following that, FT-IR and XRD analysis was provided the clear information about functional moieties and crystalline pattern of BSPAC, CuO, ZnO and BSPAC/ZnO/CuO ternary nanocomposite. The FE-SEM images of BSPAC was shown broken honey comb like structure whereas, after the fabrication of ternary nanocomposite provided spongy and rod like morphology with clustered aggregation. Then, the EDAX spectrum of BSPAC/ZnO/CuO was shown atomic weight% of carbon 27.27, oxygen 15.57, zinc 28.72 and copper 25.81 respectively. Further, HR-TEM images illustrated that spherical and rod morphology and their size was found to be 7–10 and 27–40 nm respectively. Moreover, the distinctive BET surface area of synthesized ternary nanocomposite was found to be 140.42 m²/g. The antibacterial activity of the ternary nanocomposite was tested against various Gram-positive and negative bacterial strains, and the excellent antibacterial activity was observed in B. subtilis (13.03 ± 0.08 mm), B. megaterium (14.00 ± 0.11 mm) and S. aureus (15.00 ± 0.11 mm) compared to Gram-negative bacterial strains. And also, the anticancer activity of HCT-116 cell line was shown significant outcome with IC₅₀ value of 59.18 µg/mL after 24 h treatment. These research finding confirms that the synthesized ternary nanocomposite has new insight for the development of biomedical application.

Graphical abstract

Feruloyl esterase (FAE) plays a crucial role in the biodegradation of agricultural waste. However, its limited enzymatic activity hinders its broader application. To maximize the FAE activity of the recombinant Escherichia coli strain pGEX-4T-1-BpFae^{T132C−D143C}, we systematically optimized its fermentation conditions. Furthermore, we explored its potential application in the enzymatic hydrolysis of rice husk for the simultaneous production of ferulic acid (FA) and xylo-oligosaccharides (XOS). The optimal fermentation conditions were systematically determined through a combination of single-factor experiments, Plackett-Burman (PB) design, steepest ascent path design, and response surface methodology (RSM). Under these optimized conditions—initial pH of 7.0, lactose concentration of 4.95 g/L, post-induction temperature of 25.8 °C, shaker rotational speed of 200 rpm, inoculum size of 0.1%, loading volume of 12.5 mL/250 mL, pre-induction time of 9.2 h, and post-induction time of 36 h in Terrific Broth medium—the activity of BpFae^{T132C−D143C} reached 4.43 U/mL, representing a 2.91-fold increase compared to the single-factor experiment. In a 3 L bioreactor, the total enzyme activity achieved was 1.35 U/mL. When BpFa^{eT132C−D143C} was combined with xylanase McXyn0243 for the enzymatic hydrolysis of rice husk, the yields of FA and XOS reached 67.17% and 61.59%, respectively. This demonstrated a significant synergistic effect, outperforming the results obtained when either enzyme was used independently.

Alkaline proteases from haloalkaliphilic bacteria hold significant industrial value due to their stability under harsh processing conditions. The valorization of agro-kitchen wastes into high-value bioproducts represents a key strategy for sustainable bioprocessing. In this study, waste-derived substrates were systematically explored to achieve cost-effective production of alkaline protease from the haloalkaliphilic bacterium Virgibacillus salarius VS-23, isolated from the saline desert of Kutch. Process parameters were optimized using a One Variable at a Time (OVAT) approach, yielding a maximum protease activity of 554 U/mL/min under optimal conditions (3% NaCl, pH 9, 48 h incubation, 1% casein hydrolysate, 0.5% gelatin, and 1% xylose). Screening of agricultural and kitchen wastes revealed moong water (60% v/v), brown bread (1% w/v), rice water (60% v/v), wheat bran (1% w/v), and groundnut seed cake (1% w/v) as the most effective, economical substrates for enzyme production. Notably, moong water yielded 194.59 U/mL/min, outperforming other agro-kitchen waste substrates used in this study. The protease demonstrated exceptional stability, retaining ≥ 80% activity across pH 9–12, high salinity (up to 10% NaCl), and temperatures up to 60 °C. Most significantly, the enzyme removed blood stains from cotton fabrics in just 7 min, surpassing the efficiency of conventional proteases and confirming its strong potential as a detergent additive. Overall, using readily available waste materials offers an effective and sustainable strategy for producing industrially robust alkaline proteases, supporting both economic and environmental goals.

Pyrolysis is a promising method for converting agricultural waste into valuable biofuels, yet its efficiency is often limited by high activation energy and complex reaction kinetics. Understanding the kinetic and thermodynamic behavior of the process is crucial for optimizing catalytic performance and enhancing the feasibility of large-scale applications. The kinetics and thermodynamic parameters of catalytic pyrolysis of palm empty fruit bunches (EFB) using CaO catalyst derived from scallop shells were investigated via thermogravimetry analysis at different heating rates (5, 10, and 20 °C/min). Three iso-conversional methods, namely Kissinger Akahira Sunose (KAS), Starink, and Distributed Activation Energy Model (DAEM), were utilized. The average activation energies successfully calculated were in the range of 89.62–209.18 kJ/mol for KAS, 78.17–165.89 kJ/mol for Starink, and 57.02–125.54 kJ/mol for the DAEM method. The 96.82% CaO extracted from scallop shells was shown to reduce the activation energy of EFB pyrolysis. In the presence of the catalyst, the activation energy varied from 53.16 to 94.55 kJ/mol for the KAS method, 50.73–90.22 kJ/mol for the Starink method, and 42.17–75.01 kJ/mol for the DAEM method. The EFB pyrolysis followed a second-order (R2) reaction mechanism. Each constant ΔH and ΔG was positive, while the ΔS value was negative for all EFB pyrolysis processes. The findings of this investigation are expected to be valuable for modeling and designing reactors for EFB pyrolysis, thereby aiding in the optimization of EFB pyrolysis on a commercial scale.

Bioethanol derived from organic agricultural wastes is a promising alternative fuel. The use of bioethanol, combined with the benefits of biodiesel, in compression ignition (CI) engines could be a viable solution to meet current energy demands. In this study, four blends were prepared, consisting of varying percentages of bioethanol (5–20% by volume), waste cooking oil biodiesel (20% by volume), and diesel. Tests were conducted on a single-cylinder, four-stroke diesel engine connected to an eddy-current dynamometer. The 20BE20BD60D blend showed the highest peak pressure, thermal efficiency, and volumetric efficiency, followed by the 15BE20BD65D and 10BE20BD70D blends. Fuel consumption was higher for the 10BE20BD70D and 5BE20BD75D blends. Carbon monoxide, hydrocarbon, and smoke opacity levels were lower for the biofuel blends. Diesel produced the lowest NO_x emissions compared to all the biofuel blends. The study results indicated that brake thermal efficiency improved by approximately 10.8% with the addition of ethanol to the biodiesel-diesel blend. Significantly lower emissions were observed when the engine was operated with ethanol-concentrated blends, which outperformed the B20 biodiesel mode in terms of engine performance.

Wastewater contaminated with nitrate and phosphate requires effective removal to prevent eutrophication in water bodies, a process that can lead to significant environmental and economic issues. Magnesium-modified rice husk biochar was prepared, characterized, and used for the removal of nitrate and phosphate from both synthetic and real wastewater through fixed-bed adsorption. The influence of operational variables such as flow rate (5.5–20 mL/min), bed height (4–8 cm), and initial influent concentration (20–100 mg/L) on breakthrough curves was investigated. The results revealed that as flow rate and initial concentration increased, the breakthrough curves became steeper, while their slopes decreased as bed height increased. Adsorption capacities of 9.4 mg/g and 78 mg/g were found for nitrate and phosphate, respectively, for synthetic water. Additionally, the competitive removal of nitrate and phosphate from real wastewater was studied, finding adsorption capacities of 1.4 mg/g for nitrate and 2.4 mg/g for phosphate, with a flow rate of 5.5 mL/min, bed heights ranging from 4 to 8 cm, natural pH (6.2), ambient temperature (20 °C), and respective nitrate and phosphate concentrations of 14.9 mg/L and 3.3 mg/L, being the main finding of this research the application of the studied biochar to real wastewater based on the prior study of the operational variables of the adsorption process in fixed-bed columns. Overall, Thomas, Bohart-Adams, Yoon-Nelson, and Clark models provided good fits for the breakthrough curves, enabling their application for the design and implementation of alternative treatments in wastewater treatment plants.

The use of biocatalysts, derived from biomass, bones, fruits and vegetables, is recently investigated by researchers to overcome the energy and environmental issues posed by traditional catalysts. This research investigates the effects of three biocatalysts, derived from potato, lemon, and citrus limetta peels, for the biodiesel production from waste cooking oil (WCO) and the evaluation of engine performance and emission characteristics of the WCO biodiesel blends with or without the addition of hydrogen fuel as the secondary fuel additive. Peels of potato (BC1), lemon (BC2), and citrus limetta (BC3) were used to make the biocatalysts, which were characterized using EDX and SEM. The biodiesel was produced using transesterification of WCO by mixing methanol and biocatalyst in a biodiesel reactor. The biodiesel yield and properties were tested to meet the standards. The engine performance and emission characteristics of WCO biodiesel blends were evaluated by varying the engine load (0, 25, 50, 75 and 100% of full load) and the hydrogen flow rate (0, 3, 6 and 9 lpm) in a single-cylinder 5.2 kW Kirloskar engine. EDX and SEM studies revealed that the potato peel catalyst exhibited the maximum biodiesel yield of 95%. Experimental results revealed that the BC1WC20 blend reduced CO emissions by 10% while reducing HC and CO₂ emissions by 8.3% and 5%, respectively. With the addition of hydrogen of 6 lpm, the emissions of HC and CO₂ further dropped by 12.8% and 7.4%, respectively. Furthermore, the hydrogen-enhanced BC1WC20 blend demonstrated a 19% improvement in BTE. Overall, the research showed that the vegetable peel biocatalysts, derived from the peels of potato, lemon and citrus limetta, have high potential to improve the biodiesel yield at reduced cost, and the biodiesel in combination with hydrogen could reduce pollutant emissions and improve engine efficiency.