Biocatalytic behaviour of immobilized Rhizopus oryzae lipase in the 1,3-selective ethanolysis of sunflower oil to obtain a biofuel similar to biodiesel

Comparative Study of Immobilized Biolipasa-R for Second Generation Biodiesel Production from an Acid Oil

The primary objective of this work is to develop a sustainable biocatalytic transesterification process for low-grade oils, aligning with EU green technology requirements for the shift to second generation biodiesel. Thus, we investigated the immobilization and subsequent application of the lipase Biolipasa-R on transesterification processes to produce fatty acid methyl esters (FAMEs) from both a sunflower oil and an acid oil which is a bioproduct of the biodiesel industry. The lipase was immobilized on biomaterials, such as diatomaceous earth, with a yield of 60 %, and commercial carriers such as methacrylic resins with a yield of 100 %. The enzyme demonstrated superior activity when immobilized on diatomaceous earth, particularly in reactions involving the acid oil, outperforming the benchmark enzyme Novozym® 435 (95.1 % and 35 % conversion respectively). This work highlights the potential of Biolipasa-R as a cost-effective and efficient biocatalyst for biodiesel production and emphasizes the environmental benefits of utilizing industrial byproducts and eco-friendly immobilization techniques. The findings suggest that Biolipasa-R is a promising candidate for industrial applications in biodiesel production, offering a sustainable solution for waste management and energy generation.

Biodiesel Is Dead: Long Life to Advanced Biofuels—A Comprehensive Critical Review

Many countries are immersed in several strategies to reduce the carbon dioxide (CO2) emissions of internal combustion engines. One option is the substitution of these engines by electric and/or hydrogen engines. However, apart from the strategic and logistical difficulties associated with this change, the application of electric or hydrogen engines in heavy transport, e.g., trucks, shipping, and aircrafts, also presents technological difficulties in the short-medium term. In addition, the replacement of the current car fleet will take decades. This is why the use of biofuels is presented as the only viable alternative to diminishing CO2 emissions in the very near future. Nowadays, it is assumed that vegetable oils will be the main raw material for replacing fossil fuels in diesel engines. In this context, it has also been assumed that the reduction in the viscosity of straight vegetable oils (SVO) must be performed through a transesterification reaction with methanol in order to obtain the mixture of fatty acid methyl esters (FAMEs) that constitute biodiesel. Nevertheless, the complexity in the industrial production of this biofuel, mainly due to the costs of eliminating the glycerol produced, has caused a significant delay in the energy transition. For this reason, several advanced biofuels that avoid the glycerol production and exhibit similar properties to fossil diesel have been developed. In this way, “green diesels” have emerged as products of different processes, such as the cracking or pyrolysis of vegetable oil, as well as catalytic (hydro)cracking. In addition, some biodiesel-like biofuels, such as Gliperol (DMC-Biod) or Ecodiesel, as well as straight vegetable oils, in blends with plant-based sources with low viscosity have been described as renewable biofuels capable of performing in combustion ignition engines. After evaluating the research carried out in the last decades, it can be concluded that green diesel and biodiesel-like biofuels could constitute the main alternative to addressing the energy transition, although green diesel will be the principal option in aviation fuel.

Enzymatic Production of Ecodiesel by Using a Commercial Lipase CALB, Immobilized by Physical Adsorption on Mesoporous Organosilica Materials

The synthesis of two biocatalysts based on a commercial Candida antarctica lipase B, CALB enzyme (E), physically immobilized on two silica supports, was carried out. The first support was a periodic mesoporous organosilica (PMO) and the second one was a commercial silica modified with octyl groups (octyl-MS3030). The maximum enzyme load was 122 mg enzyme/g support on PMO and 288 mg enzyme/g support on octyl-MS3030. In addition, the biocatalytic efficiency was corroborated by two reaction tests based on the hydrolysis of p-nitrophenylacetate (p-NPA) and tributyrin (TB). The transesterification of sunflower oil with ethanol was carried out over the biocatalysts synthesized at the following reaction conditions: 6 mL sunflower oil, 1.75 mL EtOH, 30 °C, 25 μL NaOH 10 N and 300 rpm, attaining conversion values over 80% after 3 h of reaction time. According to the results obtained, we can confirm that these biocatalytic systems are viable candidates to develop, optimize and improve a new methodology to achieve the integration of glycerol in different monoacylglycerol molecules together with fatty acid ethyl esters (FAEE) molecules to obtain Ecodiesel.

Rhizopus oryzae Lipase, a Promising Industrial Enzyme: Biochemical Characteristics, Production and Biocatalytic Applications

Lipases are biocatalysts with a significant potential to enable a shift from current pollutant manufacturing processes to environmentally sustainable approaches. The main reason of this prospect is their catalytic versatility as they carry out several industrially relevant reactions as hydrolysis of fats in water/lipid interface and synthesis reactions in solvent-free or non-aqueous media such as transesterification, interesterification and esterification. Because of the outstanding traits of Rhizopus oryzae lipase (ROL), 1,3-specificity, high enantioselectivity and stability in organic media, its application in energy, food and pharmaceutical industrial sector has been widely studied. Significant advances have been made in the biochemical characterisation of ROL particularly in how its activity and stability are affected by the presence of its prosequence. In addition, native and heterologous production of ROL, the latter in cell factories like Escherichia coli, Saccharomyces cerevisiae and Komagataella phaffii (Pichia pastoris), have been thoroughly described. Therefore, in this review, we summarise the current knowledge about R. oryzae lipase (i) biochemical characteristics, (ii) production strategies and (iii) potential industrial applications.

One Pot Use of Combilipases for Full Modification of Oils and Fats: Multifunctional and Heterogeneous Substrates

Lipases are among the most utilized enzymes in biocatalysis. In many instances, the main reason for their use is their high specificity or selectivity. However, when full modification of a multifunctional and heterogeneous substrate is pursued, enzyme selectivity and specificity become a problem. This is the case of hydrolysis of oils and fats to produce free fatty acids or their alcoholysis to produce biodiesel, which can be considered cascade reactions. In these cases, to the original heterogeneity of the substrate, the presence of intermediate products, such as diglycerides or monoglycerides, can be an additional drawback. Using these heterogeneous substrates, enzyme specificity can promote that some substrates (initial substrates or intermediate products) may not be recognized as such (in the worst case scenario they may be acting as inhibitors) by the enzyme, causing yields and reaction rates to drop. To solve this situation, a mixture of lipases with different specificity, selectivity and differently affected by the reaction conditions can offer much better results than the use of a single lipase exhibiting a very high initial activity or even the best global reaction course. This mixture of lipases from different sources has been called “combilipases” and is becoming increasingly popular. They include the use of liquid lipase formulations or immobilized lipases. In some instances, the lipases have been coimmobilized. Some discussion is offered regarding the problems that this coimmobilization may give rise to, and some strategies to solve some of these problems are proposed. The use of combilipases in the future may be extended to other processes and enzymes.

Biodiesel at the Crossroads: A Critical Review

The delay in the energy transition, focused in the replacement of fossil diesel with biodiesel, is mainly caused by the need of reducing the costs associated to the transesterification reaction of vegetable oils with methanol. This reaction, on an industrial scale, presents several problems associated with the glycerol generated during the process. The costs to eliminate this glycerol have to be added to the implicit cost of using seed oil as raw material. Recently, several alternative methods to convert vegetable oils into high quality diesel fuels, which avoid the glycerol generation, are being under development, such as Gliperol, DMC-Biod, or Ecodiesel. Besides, there are renewable diesel fuels known as “green diesel”, obtained by several catalytic processes (cracking or pyrolysis, hydrodeoxygenation and hydrotreating) of vegetable oils and which exhibit a lot of similarities with fossil fuels. Likewise, it has also been addressed as a novel strategy, the use of straight vegetable oils in blends with various plant-based sources such as alcohols, vegetable oils, and several organic compounds that are renewable and biodegradable. These plant-based sources are capable of achieving the effective reduction of the viscosity of the blends, allowing their use in combustion ignition engines. The aim of this review is to evaluate the real possibilities that conventional biodiesel has in order to success as the main biofuel for the energy transition, as well as the use of alternative biofuels that can take part in the energy transition in a successful way.

Synthesis, Performance and Emission Quality Assessment of Ecodiesel from Castor Oil in Diesel/Biofuel/Alcohol Triple Blends in a Diesel Engine

This research aims to promote the use of second-generation biofuels based mainly on Castor oil, which is not adequate for food use, and Sunflower oil as a standard reference for recycled oils. They have been applied in the production of Ecodiesel, a biofuel that integrates glycerol as monoglyceride, employing sodium methoxide as homogeneous catalyst and ethanol as solvent, but operating in milder conditions than in the synthesis of conventional biodiesel in order to obtain a kinetic control of the selective transesterification. The behavior of biofuels has been evaluated in a conventional diesel engine, operating as an electricity generator. The contamination degree was also evaluated from the opacity values of the generated smokes. The different biofuels here studied have practically no differences in the behavior with respect to the power generated, although a small increase in the fuel consumption was obtained in some cases. However, with the biofuels employed, a significant reduction, up to 40%, in the emission of pollutants is obtained, mainly with the blend diesel/castor oil/alcohol. Besides, it is found that pure Castor oil can be employed directly as biofuel in triple blends diesel/biofuel/alcohol, exhibiting results that are very close to those obtained using biodiesel or Ecodiesel.

Evaluation of Lipases from Wild Microbial Strains as Biocatalysts in Biodiesel Production

In this study, the evaluation of the catalytic behavior of several wild bacterial strains in the 1,3-selective ethanolysis of triglycerides with ethanol to produce a new type of biodiesel (Ecodiesel) that integrates glycerol as monoacylglycerols was carried out. The Ecodiesel production not only avoids the elimination of glycerol, which is largely generated as a by-product in the biodiesel industry, but also results in an increase in the biofuel yield. The wild microbial strain samples were obtained from several lipophilic organisms. In addition to evaluate the enzymatic extracts, the minimum grade of purification of the strains, necessary to obtain similar results to those attained with commercial lipases was studied. This purification treatment included a dialysis followed by a lyophilization process. Such extracts were directly used as biocatalysts in the transesterification reaction of sunflower oil with ethanol, attaining much better results (yield close to 100%) than those obtained with strains which were not submitted to the purification process (yields lower than 10%). Furthermore, the results here obtained are similar to those obtained with commercial lipases but were achieved under mild conditions and lower reaction time (2 h). In addition, the stability of the enzymatic extracts was corroborated by subsequent reactions, showing no loss of activity. Thus, this study brings to light that enzymatic extracts obtained by a very simple purification process can be economically competitive with the conventional biodiesel production methods.

Application of Enzymatic Extracts from a CALB Standard Strain as Biocatalyst within the Context of Conventional Biodiesel Production Optimization

The application of biocatalysts in the transesterification process of triglycerides (TG) allows integrating the glycerol in the form of monoglyceride (MG), sharply increasing the yield and the environmental sustainability of the conventional biodiesel production process. This is known as Ecodiesel. To overcome the inconvenient of the high cost of the currently employed highly purified commercial enzymes, the use of scarcely purified extracts obtained from standard strains of the same species of commercial lipases currently applied in this process is being investigated. Thus, Candida antarctica type B (CALB) was chosen to determine the optimal conditions of culture of this yeast. The standard strain was obtained from the Spanish Type Microbial Cultures Collection (CECT) and has been used to carry out several studies to elucidate its optimum growth conditions. Through a process of lyophilization with prior dialysis of the liquid cultures, the enzymatic extracts were obtained. The different obtained cultures have been applied as biocatalysts in the 1,3-selective transesterification reaction of sunflower oil with ethanol to obtain Ecodiesel (FAEE + MG). Selectivity and reaction yields were obtained by gas chromatography. Acceptable yields are obtained during the reaction time as well as in successive reactions, demonstrating the feasibility of using these CALB enzymatic extracts as biocatalysts.

Functional Nanocomposites Based on Fibrous Clays

This chapter is focused on functional nanocomposites based on the use of the microfibrous clays sepiolite and palygorskite as efficient fillers for diverse types of polymer matrices, from typical thermoplastics to biopolymers. The main features that govern the interaction between the silicates and the polymer matrix are discussed. The introduction addresses the structural and textural features of the fibrous silicates, as well as the possible synthetic approaches to increase the compatibility of these nanofillers with the polymeric matrix. Additionally, these clays can be easily functionalized through their surface silanol groups based on chemical reactions or by anchoring of nanoparticles. This allows for the preparation of a wide variety of functional polymer–clay nanocomposites. Thereafter, some relevant examples of nanocomposites derived from conventional polymers are reported, as well as of those based on polymers that exhibit electrical conductivity. Lastly, selected works employing sepiolite or palygorskite as fillers in polymeric matrixes of natural origin are discussed, showing the wide application of these resulting nanocomposites as bioplastics, as well as in biomedicine, environmental remediation and the development of sensor devices.

Biodiesel production from crude Jatropha oil catalyzed by non-commercial immobilized heterologous Rhizopus oryzae and Carica papaya lipases

The aim of this study was to evaluate the feasibility of biodiesel production by transesterification of Jatropha oil with methanol, catalyzed by non-commercial sn-1,3-regioselective lipases. Using these lipases, fatty acid methyl esters (FAME) and monoacylglycerols are produced, avoiding the formation of glycerol as byproduct. Heterologous Rhizopus oryzae lipase (rROL) immobilized on different synthetic resins and Carica papaya lipase (rCPL) immobilized on Lewatit VP OC 1600 were tested. Reactions were performed at 30°C, with seven stepwise methanol additions. For all biocatalysts, 51-65% FAME (theoretical maximum=67%, w/w) was obtained after 4h transesterification. Stability tests were performed in 8 or 10 successive 4h-batches, either with or without rehydration of the biocatalyst between each two consecutive batches. Activity loss was much faster when biocatalysts were rehydrated. For rROL, half-life times varied from 16 to 579h. rROL on Lewatit VPOC 1600 was more stable than for rCPL on the same support.