Enzyme catalyzed transesterification of waste cooking oil with dimethyl carbonate

Synthesis of lipophilic arbutin ester by enzymatic transesterification in high pressure carbon dioxide

In this study, a novel one-step enzymatic acylation was developed for the synthesis of hydrophobic arbutin ester, by using supercritical carbon dioxide (SC-CO₂) as the reaction solvent. Immobilized Novozym 435 from Candida antarctica was identified as the best biocatalyst for producing arbutin palmitate through transesterification between arbutin and palmitic acid ethyl ester in SC-CO₂. A transesterification yield of 85.21 % was obtained in batch operation using palmitic acid ethyl ester as the acyl donor, hexane/propylene glycol as the co-solvent and Novozym 435 as the enzyme at 10 MPa and 60 °C for 20 h in SC-CO₂. The yield of arbutin palmitate increased with increasing temperature over the range of 40-60 °C in the current study. Operating at an arbutin/palmitic acid ethyl ester molar ratio of 5.0, the conversion of arbutin decreased, probably due to an inhibitory effect of the high concentration of palmitic acid ethyl ester on the enzyme. The 38 % original enzyme activity of Novozym 435 was maintained after being used for 3 cycles (60 h) under optimized conditions.

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.

Immobilization of Lipase A from Candida antarctica onto Chitosan-Coated Magnetic Nanoparticles

In this communication, lipase A from Candida antarctica (CALA) was immobilized by covalent bonding on magnetic nanoparticles coated with chitosan and activated with glutaraldehyde, labelled CALA-MNP, (immobilization parameters: 84.1% ± 1.0 for immobilization yield and 208.0 ± 3.0 U/g ± 1.1 for derivative activity). CALA-MNP biocatalyst was characterized by X-ray Powder Diffraction (XRPD), Fourier Transform Infrared (FTIR) spectroscopy, Thermogravimetry (TG) and Scanning Electron Microscope (SEM), proving the incorporation of magnetite and the immobilization of CALA in the chitosan matrix. Besides, the immobilized biocatalyst showed a half-life 8-11 times higher than that of the soluble enzyme at pH 5-9. CALA showed the highest activity at pH 7, while CALA-MNP presented the highest activity at pH 10. The immobilized enzyme was more active than the free enzyme at all studied pH values, except pH 7.

Estimating total lipid content of Camelina sativa via pyrolysis assisted in-situ transesterification with dimethyl carbonate

Direct derivatization of C. sativa seed into FAMEs without lipid extraction was conducted for the quantification of lipid analysis via in-situ thermal methylation with dimethyl carbonate as an acyl acceptor on silica (SiO₂). The introduced method had an extraordinarily high tolerance against impurities such as pyrolytic products and moisture. To ensure the technical completeness of in-situ methylation, thermal cracking of FAMEs transformed from C. sativa seed was also explored. Thermal cracking of unsaturated FAMEs such as C_18:1, C_18:2, C_18:3 and C_20:1 occurred at temperatures higher than 365°C due to their thermal instability. Thus, experimental findings in this study suggests not only that qualitative analysis of fatty acid profile in C. sativa seed via in-situ methylation using SiO₂ could be achieve, but also that the total lipid content (42.65wt.%) in C. sativa seed could be accurately estimated.

In-situ pyrogenic production of biodiesel from swine fat

In-situ production of fatty acid methyl esters from swine fat via thermally induced pseudo-catalytic transesterification on silica was investigated in this study. Instead of methanol, dimethyl carbonate (DMC) was used as acyl acceptor to achieve environmental benefits and economic viability. Thermo-gravimetric analysis of swine fat reveals that swine fat contains 19.57wt.% of water and impurities. Moreover, the fatty acid profiles obtained under various conditions (extracted swine oil+methanol+NaOH, extracted swine oil+DMC+pseudo-catalytic, and swine fat+DMC+pseudo-catalytic) were compared. These profiles were identical, showing that the introduced in-situ transesterification is technically feasible. This also suggests that in-situ pseudo-catalytic transesterification has a high tolerance against impurities. This study also shows that FAME yield via in-situ pseudo-catalytic transesterification of swine fat reached up to 97.2% at 380°C. Therefore, in-situ pseudo-catalytic transesterification can be applicable to biodiesel production of other oil-bearing biomass feedstocks.

Enzymatic transesterification for biodiesel production: a comprehensive review

Biodiesel catalyzed by enzyme is affected by many factors. This review will critically discuss the three major components of enzymatic production of biodiesel and the methods used to improve the reaction.

Ultrasound assisted enzyme catalyzed degradation of Cetirizine dihydrochloride

Cetirizine dihydrochloride, a pharmaceutical drug of the class antihistamines is frequently detected in wastewater samples. In the present work, the degradation of Cetirizine dihydrochloride is carried out using a novel technique of laccase enzyme as a catalyst under the influence of ultrasound irradiation. Effect of various process parameters such as enzyme loading, temperature, power, duty cycle, frequency and speed of agitation has been studied along with identification of the degradation intermediates. The maximum degradation of 91% is achieved at optimized experimental parameters such as 0.02% enzyme loading (w/v), 50°C temperature, power input of 100 W, 25 kHz frequency and 50% duty cycle with agitation speed of 200 rpm. It is observed that enzymatic degradation of Cetirizine dihydrochloride under the influence of ultrasound irradiation not only enhances the degradation but also reduces the time of degradation as compared to conventional enzymatic degradation technique.

Continuous esterification of free fatty acids in crude biodiesel by an integrated process of supercritical methanol and sodium methoxide catalyst

An integrated process of supercritical methanol (SCM) and sodium methoxide catalyst was developed to produce fatty acid methyl esters (FAMEs) via continuous esterification from crude biodiesel. The crude biodiesel with high free fatty acid (FFA) content must be refined to reduce the acid value (AV) for meeting the quality standards. The process parameters were studied by Box-Behnken design (BBD) of response surface methodology (RSM). The experimental results revealed that the AV of crude biodiesel decreased from 18.66 to 0.55 mg KOH g(-1) at the reaction conditions of 350 °C, 0.5 % amount of sodium methoxide catalyst, and 10 MPa. Temperature shows the most significant effect on the esterification, followed by pressure and amount of sodium methoxide catalyst. This integrated process proved to be a potential route to refine the crude biodiesel because of its continuity, high efficiency, and less energy consumption with relatively moderate reaction conditions compared with conventional methods.

Production of biodiesel fuel from canola oil with dimethyl carbonate using an active sodium methoxide catalyst prepared by crystallization

In this study, a novel method for the production of biodiesel under mild conditions using fine particles of sodium methoxide formed in dimethyl carbonate (DMC) is proposed. Biodiesel is generally produced from vegetable oils by the transesterification of triglycerides with methanol. However, this reaction produces glycerol as a byproduct, and raw materials are not effectively utilized. Transesterification with DMC has recently been studied because glycerol is not formed in the process. Although solid-state sodium methoxide has been reported to be inactive for this reaction, the catalytic activity dramatically increased with the preparation of fine catalyst powders by crystallization. The transesterification of canola oil with DMC was studied using this catalyst for the preparation of biodiesel. A conversion greater than 96% was obtained at 65°C for 2h with a 3:1M ratio of DMC and oil and 2.0 wt% catalyst.