Journal of Energy Bioscience 2025, Vol.16, No.2, 53-63 http://bioscipublisher.com/index.php/jeb 55 pretreated biomass (Zaafouri et al., 2017). The hydrolysates obtained are then subjected to fermentation, where microorganisms convert the sugars into ethanol. Two main fermentation pathways are employed: Separate Hydrolysis and Fermentation (SHF) and Simultaneous Saccharification and Fermentation (SSF). SHF involves separate stages for hydrolysis and fermentation, while SSF combines both processes in a single step, often resulting in higher ethanol yields (Robak and Balcerek, 2018; Wawro et al., 2019; 2021). 3.3 Challenges and advances in optimizing bioethanol yield One of the primary challenges in bioethanol production from hemp biomass is the efficient conversion of both hexose and pentose sugars. Traditional yeast strains like Saccharomyces cerevisiae are efficient at fermenting glucose but not xylose, necessitating the use of genetically engineered or alternative microorganisms for co-fermentation (Robak and Balcerek, 2018). Another challenge is the presence of inhibitors formed during pretreatment, which can hinder enzymatic activity and microbial fermentation. Detoxification steps, such as the use of activated charcoal, can mitigate these effects (Robak and Balcerek, 2018; Chaudhary et al., 2021). Recent advances have focused on optimizing pretreatment conditions and enzyme formulations to maximize sugar yields. For example, the use of response surface methodology (RSM) has been effective in determining optimal conditions for enzymatic hydrolysis, leading to significant improvements in glucose release (Wawro et al., 2019; Chen et al., 2021; Wawro et al., 2021). Additionally, innovative approaches such as consolidated bioprocessing (CBP), which integrates enzyme production, hydrolysis, and fermentation in a single step, are being explored to enhance process efficiency and reduce costs (Robak and Balcerek, 2018; Chen et al., 2021). 4 Hemp-based Biodiesel Production 4.1 Extraction and conversion of hemp seed oil for biodiesel The extraction of hemp seed oil is a critical step in the production of biodiesel. Industrial hemp (Cannabis sativa L.) seeds are known for their high oil content, which makes them a viable feedstock for biodiesel production. The oil extraction process typically involves mechanical pressing or solvent extraction methods. Once extracted, the hemp seed oil undergoes a conversion process to transform it into biodiesel. This conversion is primarily achieved through a chemical reaction known as transesterification, where triglycerides in the oil react with alcohol (usually methanol) in the presence of a catalyst to form fatty acid methyl esters (FAMEs), which constitute biodiesel (Li et al., 2010; Yilbaşi et al., 2021). 4.2 Transesterification process and catalysts used The transesterification process is central to biodiesel production from hemp seed oil. This process can be catalyzed by various substances, including alkali, acid, and enzymes. Base-catalyzed transesterification is the most common method due to its high conversion efficiency and relatively mild reaction conditions. For instance, potassium hydroxide (KOH) and sodium hydroxide (NaOH) are frequently used as catalysts in this process. Optimal conditions for base-catalyzed transesterification of hemp seed oil include a methanol-to-oil molar ratio of 6:1, a catalyst concentration of 0.9 wt.%, a reaction temperature of 45 ℃, and a reaction duration of 120 minutes, resulting in a biodiesel yield of up to 96.87% (Yilbaşi et al., 2021). Enzyme-catalyzed transesterification, using lipases, offers a greener alternative by reducing the formation of by-products and operating under milder conditions. For example, Lipozyme TL IM (Thermomyces lanuginosus) has been identified as an effective biocatalyst for the in situ transesterification of oils with high free fatty acid content (Santaraite et al., 2020). Additionally, heterogeneous catalysts derived from renewable sources, such as calcined banana peduncle ash, have shown promise in biodiesel production, offering high yields and reusability (Balajii and Niju, 2020). 4.3 Comparative analysis with traditional biodiesel feedstocks Hemp seed oil presents several advantages over traditional biodiesel feedstocks such as soybean and rapeseed oils. One significant benefit is the high polyunsaturated fatty acid content in hemp seed oil, which contributes to a lower cloud point and kinematic viscosity, enhancing the cold flow properties of the biodiesel (Li et al., 2010). Moreover, the unique 3:1 ratio of linoleic to alpha-linolenic acid in hemp seed oil is favorable for biodiesel quality.
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