A catalyst from the pharmaceutical waste of calcium and magnesium tablets was synthesized for biodiesel production from waste Pistacia-Terebinthus (PT) oil with the aim of creating added value and presenting a new approach for the management of such wastes. For this purpose, magnesium and calcium tablet wastes with a mass ratio of 70:30 (wt%) were calcined. The catalyst was investigated by several methods, such as thermal gravimetric analysis, X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, Brunauer-Emmett-Teller analysis, X-ray photoelectron spectroscopy, and CHNS/O elemental analysis. The high specific surface area of the catalyst confirms that the utilized synthesis method resulted in the formation of a high number of active sites in its structure, which allows it to function as a suitable catalyst for this reaction. Furthermore, the impact of effective parameters on the treansestrification reaction was optimized and investigated by designing the experiments and applying the RSM method. The maximum mass yield of 96 % was obtained in optimal conditions (temperature of 70 °C, catalyst loading of 4.498 wt%, methanol:oil ratio of 1.968 (vol:vol), and reaction time of 120 min). The reusability of the catalyst was investigated in four successive cycles. The mass yield of the last test declined from 96 % to 71.4 %. Gas chromatography-mass spectrometry analysis of the produced biofuel revealed that it comprises 91.37 % methyl ester compounds (64.28 % 12-Octadecenoic Acid, Methyl Ester). To evaluate the external costs of biofuel (B100) and compare it with diesel, combustion simulation was done with Diesel-RK software, which showed that its external costs were 0.05388 (€/Lit fuel) less than those of diesel.

The urgent need for mitigating climate change necessitates a transformative shift in energy production and consumption paradigms. Amidst this challenge, bioenergy emerges as a pivotal contributor to the global energy transition, offering a diverse array of solid, liquid, and gaseous fuels derived from biomass. This mini review delves into the unique potential of bioenergy innovations, particularly renewable diesel, bio jet fuel, and ethanol, to reduce greenhouse gas emissions and transform various industries. The article highlights critical technological advancements, supportive policies, and cross-sector collaboration essential for a sustainable energy transition. Specific challenges such as ensuring a consistent biomass feedstock supply, decentralizing processing units, and navigating complex regulatory frameworks are examined. Innovative solutions like decentralized biomass processing and enhanced biomass logistics are discussed as pathways to overcome these barriers. The review provides specific recommendations for near-term policies and strategies to support decentralized facilities, showcasing bioenergy\'s role in achieving a sustainable future.

Microalgal oil production represents a promising renewable biofuel source. Metabolic engineering can enhance its utility, transforming it into an improved biofuel and expanding its applications as a feedstock for commodity chemicals, thereby increasing their value in biorefineries. This study focused on anaerobic wax ester production by the microalga Euglena gracilis, aiming to develop stable mutant strains with altered wax ester profiles through genome editing. Two enzymes in the fatty acid beta-oxidation pathway involved in wax ester production were targeted-3-ketoacyl-CoA thiolase and acyl-CoA dehydrogenase-using clustered regularly interspaced short palindromic repeats/Cas9. The results revealed one genetic mutation that lengthened and three that shortened the distribution of wax ester compositions compared to the wild-type (WT). The triple-KO mutant, combining mutations that shorten wax ester chains, produced wax esters with acyl chains two carbons shorter than WT. This study established a methodology to stably modify wax ester composition in E. gracilis.

Enhancing stalk strength is a crucial strategy to reduce lodging. We identified a maize inbred line, QY1, with superior stalk mechanical strength. Comprehensive analyses of the microstructure, cell wall composition, and transcriptome of QY1 were performed to elucidate the underlying factors contributing to its increased strength. Notably, both the vascular bundle area and the thickness of the sclerenchyma cell walls in QY1 were significantly increased. Furthermore, analyses of cell wall components revealed a significant increase in cellulose content and a notable reduction in lignin content. RNA sequencing (RNA-seq) revealed changes in the expression of numerous genes involved in cell wall synthesis and modification, especially those encoding pectin methylesterase (PME). Variations in PME activity and the degree of methylesterification were noted. Additionally, glycolytic efficiency in QY1 was significantly enhanced. These findings indicate that QY1 could be a valuable resource for the development of maize varieties with enhanced stalk mechanical strength and for biofuel production.

Biofuels have emerged as a promising and eco-friendly alternative to conventional fossil fuels. Biofuel sourced from rice straw (RS) and municipal solid waste (MSW), which are abundant residues from agricultural and municipal activities, present a sustainable solution to address waste management challenges. Utilizing life cycle assessment, this study quantifies the environmental advantages by assessing the reduction in greenhouse gas emissions, energy consumption, and other environmental impacts linked with employing these waste materials for biofuel production. Employing a cradle-to-gate approach as the system boundary for bioethanol production, with the functional unit set as per liter of bioethanol produced, the analysis reveals that the global warming potential (GWP) for ethanol from MSW is 4.4 kg CO2 eq., whereas for RS, it is 2.1 kg CO2 eq. per functional unit. The total environmental impacts were primarily due to enzymatic hydrolysis and electricity consumption for ethanol production from MSW and RS. Despite advancements, fossil fuel consumption remains a potential energy source for biofuel production. The cumulative energy demand stands at 18.6 MJ for RS and 71.5 MJ for MSW per functional unit, underscoring the potential to significantly reduce overall impacts by transitioning to a more environmentally sustainable energy source. The uncertainty analysis acknowledges the inherent uncertainties associated with data, assumptions, and methodologies, highlighting the crucial need for ongoing research and updates to enhance the accuracy of future assessments. This analysis forms the foundation for well-informed decision-making, providing valuable insights for policymakers, industry stakeholders, and consumers.

Temperature-dependent rate coefficients for the reactions of 2-methyl tetrahydrofuran (MTHF) with Cl atoms in the temperature range of 268-343 K at atmospheric pressure were measured using the relative-rate method. Ethylene and propane were used as reference compounds. Quantitative analysis of the post-photolysis reaction mixture was conducted using a gas chromatograph paired with a flame ionization detector (GC-FID). A gas chromatograph connected to a mass spectrometer (GC-MS) was employed for the purpose of qualitative analysis. In the experimental temperature range, the derived Arrhenius expression for the title reaction is represented by the equation k M T H F + C l Expt 268 - 343 K = ( 1.48 ± 0.13 ) × 10 - 12 × e x p 1474.51 ± 25.16 T cm3 molecule-1 s-1. In addition to our experimental findings, we conducted computational calculations employing the CCSD(T)//BHandHLYP/6-31 + G(d,p) level of theory to complement our study. The canonical transition state theory (CTST) was utilized to compute the rate coefficients at 250-400 K and 760 Torr. The Arrhenius expression for the theoretically calculated \"k\" values is found to be k M T H F + C l Theory 250 - 400 K = ( 1.51 ± 0.10 ) × 10 - 12 × e x p 1544.97 ± 22.14 T cm3 molecule-1 s-1. The local reactivity parameters, such as Fukui functions ( f r 0 ), local softness ( s r 0 ), and global softness ( S ) were also calculated theoretically to understand the site-specific reactivity trend of MTHF towards Cl atoms. The atmospheric implications, branching ratios, degradation mechanism, and feasibility of the reaction are discussed in this study.

Microalgae cultures have emerged as a promising strategy in diverse areas, ranging from wastewater treatment to biofuel production, thus contributing to the search for carbon neutrality. These photosynthetic organisms can utilize the resources present in wastewater and fix atmospheric CO2 to produce biomass with high energy potential. In this study, the removal efficiency of Polycyclic Aromatic Hydrocarbons (PAHs), CO2 fixation and lipid content in the biomass produced from microalgae grown in airlift photobioreactor were evaluated. Four mesoscale cultures were carried out: Control (Seawater + Conway medium), Treatment A (Oil Produced Water + Poultry Effluent Water), Treatment B (Poultry Effluent Water + Seawater) and Treatment C (Oil Produced Water, Seawater and nutrients). The impact of biostimulation, through the addition of nutrients, on PAHs removal efficiency (up to 90%), CO2 fixation rate (up to 0.20 g L-1 d-1) and the composition of the generated biomass was observed. Primarily, the addition of nitrates to the culture medium impacted CO2 fixation rate of the microalgae. In addition, a direct correlation was observed between PAHs removal and lipid accumulation in the biomass, up to 36% in dry weight, demonstrating microalgae\'s ability to take advantage of the organic carbon (PAHs) present in the culture medium to generate lipid-rich biomass. The concentration of polysaccharides in the biomass obtained did not exceed 12% on a dry weight basis, and the Higher Heating Value (HHV) ranged between 17 and 21 MJ kg-1. Finally, the potential of generating hydrogen through pyrolysis was highlighted, taking advantage of the characteristics of biomass as a conversion route to produce biofuels. These results show that microalgae are effective in wastewater treatment and have great potential in producing biofuels, thus contributing to the transition towards more sustainable energy sources and climate change mitigation.

Cyanobacteria are oxygen-evolving prokaryotes that can be engineered for biofuel production from solar energy, CO2, and water. Isobutanol (IB) has the potential to serve as an alternative fuel and important chemical feedstock. The research involves engineering Synechocystis sp. PCC 6803, for photosynthetic isobutanol production via the 2-keto-acid pathway and their cultivation in lab-scale photobioreactors. This synthetic pathway involves the heterologous expression of two enzymes, α-ketoisovalerate decarboxylase (Kivd) and alcohol dehydrogenase (Yqhd), under a strong light-inducible promotor, psbA2, known to show increased gene expression under high light. The use of psbA2 could be a valuable strategy for isobutanol production as economic scaling up demands the utilization of natural sunlight, which also provides very high light intensity at midday, facilitating increased production. The study reports isobutanol production from engineered strains containing both pathway genes and with only kivd. In shake flask studies, the highest isobutanol titre of 75 mg L-1 (12th day) was achieved from an engineered strain DM12 under optimized light intensity. DM12 was cultivated in a 2 L flat panel photobioreactor, resulting in a maximum isobutanol titre of 371.8 mg L-1 (10th day) with 2 % CO2 and 200 μmol photons m-2 s-1. Cultivation of DM12 in a photobioreactor under mimic diurnal sunlight demonstrated the highest productivity of 39 mg L-1 day-1 with the maximum titre of 308.5 mg L-1 (9th day). This work lays the foundation for sustainable, large-scale biobutanol production using solar energy.

In this paper, the experiment of cellulose from corn stalk using 1, 2-propylene glycol (PG) and diethylene glycol (DEG) liquefaction catalyzed by phosphoric acid at atmosphere pressure was carried out. The effect of reaction time on the structural changes of cellulose in the liquefaction process of polyhydric alcohols was investigated, aiming at understanding the mechanism of cellulose liquefaction reaction under the action of acid catalyzed polyhydric alcohols. It was found that the liquefaction yield increased first and then decreased with the extension of reaction time, and reached the highest at 150 min (99.34 %). In the phase of increasing liquefaction yield, cellulose was degraded and translated into glucose, which was then converted into plenty of glycosides with PG/DEG. These glycosides were further converted into low molecular weight (LMW) substances such as hydrocarbons, acids, alcohols, esters, ketones, and ethers. At this time, the biofuel contained 70 %-85 % compounds with carbon number less than 25 and 5 %-10 % compounds with carbon number more than 25. As the prolongation of reaction time (after 150 min), quantities of unstable free radicals formed by cellulose degradation could combine with each other or with hydrogen atoms provided by PG/DEG to produce relatively stable macromolecular substances. That is, the polydispersity (Mw/Mn, abbreviated Р= 1.28) of the generated biofuel at this stage no longer decreased. However, liquefaction residue produced at 240 min had changed essentially, which was completely different from the liquefaction residue produced in the early stage of liquefaction. In conclusion, this paper revealed the partial reaction process of cellulose by studying the structural changes in the liquefaction process of polyhydric alcohols, which laid a theoretical foundation for exploring the liquefaction mechanism of cellulose.

Hydrogen (H2), a clean and versatile energy carrier, has recently gained significant attention as a potential solution for reducing carbon emissions and promoting sustainable energy systems. The yield and efficiency of the biological H2 production process primarily depend on sterilization conditions. Various strategies, such as heat inactivation and membrane-based sterilization, have been used to achieve desirable yields via microbial fermentation. Almost every failed biotransformation process is linked to nonsterile conditions at any reaction stage. Therefore, the production of renewable biofuels as alternatives to fossil fuels is more attractive. Pure sugars have been widely documented as a costly feedstock for H2 production under sterile conditions. Biotransformation under nonsterile conditions is more desirable for stable and sustainable operation. Low-cost feeds, such as biowaste, are considered suitable alternatives, but they require appropriate sterilization to overcome the limitations of inherited or contaminating microbes during H2 production. This article describes the status of microbial fermentative processes for H2 production under nonsterile conditions and discusses strategies to improve such processes for sustainable, cleaner production.