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Predictive monitoring of two key properties of nanocellulose, aspect ratio and yield of nanofibrillation, would help manufacturers control and optimize production processes, given the uncertainty that still surrounds their influential factors. For that, 20 different types of cellulosic and lignocellulosic micro/nanofibers produced from spruce and pine softwoods, and by different pre-treatment and fibrillation techniques, were used as training and testing datasets aiming at the development and evaluation of three machine learning models. The models used were Random Forests (RF), Linear Regression (LR) and Artificial Neural Networks (ANN), broadening the scope of our previous work (Santos et al. in Cellulose 29:5609–5622, 2022. https://doi.org/10.1007/s10570-022-04631-5). Performance of these models were evaluated by comparing statistical parameters such as Mean Absolute Percentage Error (MAPE) and R². For the aspect ratio and the yield of nanofibrillation, inputs were chosen among these easily controlled or measured variables: Total lignin (wt%), Cellulose (wt%), Hemicellulose (wt%), Extractives (wt%), HPH Energy Consumption (kWh/kg), Cationic Demand (µeq/g), Transmittance at 600 nm and Consistency index (Ostwald-De Waele’s k). In both cases, the ANN models trained here provided satisfactory estimates of aspect ratio (MAPE = 4.54% and R2 = 0.96) and the yield of nanofibrillation (MAPE = 6.74% and R2 = 0.98), being able to capture the effect of the applied energy along the fibrillation process. RF and LR models resulted in correlation coefficients of 0.93 and 0.95, respectively, for aspect ratio, while for yield of nanofibrillation the correlation coefficients were 0.87 and 0.92. The present work has been funded by the Spanish Ministry of Science and Innovation, projects CON-FUTURO-ES (PID2020-113850RBC22) and VALORCON-NC (PDC2021-120964-C22). Alexandre Ferreira Santos received funding from the Conselho Nacional de Desenvolvimento Científco e Tecnológico (CNPq, Brazil) for his research stay at University of Girona. The Human Resources Program of the National Agency of Petroleum, Natural Gas and Biofuels (PRH-ANP/Finep) from Brazil has economically supported the grant of Giovana S. Iamin. Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature.

In this work a wide sample analysis, under similar conditions, has been carried out and a calibration strategy based on a careful selection of input variables combined with sensitivity analysis has enabled us to build accurate neural network models, with high correlation (R > 0.99), for the prediction of the aspect ratio of micro/nanofiber products. The model is based on cellulose content, applied energy, fiber length and diameter of the pre-treated pulps. The number of samples used to generate the neural network model was relatively low, consisting of just 15 samples coming from pine pulps that had undergone thermomechanical, kraft and bleached kraft treatments to produce a significant range of aspect ratio. However, the ANN model, involving 4 inputs and 4 hidden neurons and calibrated on the basis of pine dataset, was accurate and robust enough to predict the aspect ratio of micro/nanofiber materials obtained from other cellulose sources including very different softwood and hardwood species such as Spruce, Eucalyptus and Aspen (R = 0.84). The neural network model was able to capture the nonlinearities involved in the data providing insight about the profile of the aspect ratio achieved with further homogenization during the fibrillation process The authors wish to acknowledge the fnancial support of the Spanish Ministry of Science and Innovation to the project CON-FUTURO-ES (PID2020-113850RB-C21 and PID2020-113850RB-C22) and VALORCON-NC (PDC2021- 120964-C21 and PDC2021-120964-C22). Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature.

Made available in DSpace on 2022-04-28T19:42:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-08-12 This paper reports experimental results and thermodynamic modeling of the liquid-liquid equilibrium (LLE) of the system chicha biodiesel (Sterculia striata) + glycerol + ethanol. Binodal curves and tie lines were obtained at different temperatures (303.15, 318.15, and 333.15 K) and atmospheric pressure (101.3 kPa). The quality of the experimental data was evaluated using the criteria of Marcilla and co-workers. The nonrandom two-liquid (NRTL) and analytical solutions of groups (ASOG) models were used to correlate the LLE data. Both models well fitted the experimental data with root-mean-square deviations (rmsd) not greater than 1.5%. Laboratory of Separation Systems and Process Optimization (LASSOP) Center of Technology Federal University of Alagoas, Alagoas Department of Chemical Engineering Federal University of Parana, Paraná Engineering School of Lorena Department of Chemical Engineering University of Sao Paulo (USP), São Paulo Department of Energy Engineering Sao Paulo State University (UNESP), São Paulo Department of Energy Engineering Sao Paulo State University (UNESP), São Paulo

Lipids and coumarin were extracted from cumaru seeds using Soxhlet extraction (SE) with ethanol (EtOH) and ethyl acetate (EtOAc), scCO2, scCO2 +EtOH and scCO2 +EtOAc, either in a single or in sequential stages, and with PLE with EtOH. ScCO2 +EtOAc provided yields from 28% to 31%, independently of the extraction conditions employed, and scCO2 +EtOH provide a top yield of 38%, at 25MPa and 80 ºC. Extraction yields were enhanced by three sequential extractions, resulting in yields of 44.0% and 56.5% for scCO2 +EtOAc and scCO2 +EtOH, respectively, where these values were superior to those obtained in SE. This work also reported the kinetics of coumarin extraction using scCO2 +cosolvents, where in the case of scCO2 +EtOH the coumarin content was 30mgg−1 of extract. Finally, the coumarin crystals seemed to be affected by the cosolvent nature, as indicated by the higher antioxidant activity of coumarin-rich extracts obtained by scCO2 +EtOAc, rather than those obtained by scCO2 +EtOH.

The search for sustainable ideas has gained prominence in recent decades at all levels of society since it has become imperative an economic, social, and environmental development in an integrated manner. In this context, biorefineries are currently present as the technology that best covers all these parameters, as they add the benefits of waste reuse, energy cogeneration, and fossil fuel substitution. Thus, the study of the various applicable biological matrices and exploring the technical capabilities of these processes become highly attractive. Thermodynamic modeling acts in this scenario as a fundamental tool for phase behavior predictions in process modeling, design, and optimization. Thus, this work aimed to systematize, using the PRISMA statement for systematic reviews, the information published between 2010 and 2020 on phase equilibria modeling in systems related to biorefineries to organize what is already known about the subject. As a result, 236 papers were categorized in terms of the year, country, type of phase equilibria, and thermodynamic model used. Also, the phase behavior predictions of different thermodynamic models under the same process conditions were qualitatively compared, establishing PC-SAFT as the model that best represents the great diversity of interest systems for biorefineries in a wide range of conditions.

In this work, a novel method was proposed for the conversion of waste cooking oil into biodiesel. A two-step approach based on a pretreatment with AlCl3•6H2O to convert FFA into the relevant methyl esters, followed by the complete transesterification of glycerides, under KOH catalysis in a reactive distillation column, was considered. The pretreatment with AlCl3•6H2O allowed to obtain two different phases: an oily phase, rich in FAME and triacylglycerols and with a very limited content of water (100 ppm), and residual FFA (1 mgKOH /goil), and a methanol phase, in which most of the catalyst, water and monoacylglycerols were dissolved in. The esterified stream was characterized by its composition and used to obtain new kinetic parameters to be used in the setting of the reactive distillation. The reactive distillation column was proved to be efficient in obtaining a biodiesel stream with a purity requirement conform to the EN14214 standards. The transesterification step was characterized by a specific heating requirement of 701.3 kJ per kg of biodiesel produced

The circular economy concept applied to the management of spent coffee grounds (SCG) is an opportunity to obtain a portfolio of high added-value products and reducing the environmental impact while increasing the profitability and reducing the energy consumption of the soluble coffee production process. A systematic analysis of the alternatives is performed to unveil integration opportunities and find synergies aiming at the optimal set of processes and products. In this work, five products, dry natural extract, dry natural pigment for the textile industry, biogas, digestate, and electrical energy, through three different processes are considered. The use of SCG to produce biodiesel is discarded after prescreening. A systematic techno-economic analysis of all processes is carried out, and two processes were found economically promising, the production of power and the production of natural extract and pigment. The production of natural pigment and natural extract is the most profitable process, with a profit 40 times larger than the production of electrical energy. The operation and investment costs are 4.59 MM€/year and 13.97 MM€, respectively. Therefore, it is possible to achieve economic benefit from the treatment of this waste.

The pulp and paper sector is undertaking several initiatives to decrease the carbon footprint of its industrial activities. To do so, any emission must be offset by introducing efficient carbon fixation strategies such as reforestation and the development of biobased products and processes. The production of drop-in fuels may play an important role in this scenario. Drop-in fuels provide a good way to add value to otherwise underutilized process streams and wastes, reducing greenhouse gas emissions, minimizing other environmental impacts, and improving process sustainability.

Cetyl palmitate was produced by the esterification of palmitic acid with cetyl alcohol using n-hexane as solvent and a fermented solid of Burkholderia contaminans as catalyst. Effects of temperature (35–55 °C) and alcohol:acid molar ratio (0.5:1–2:1) on the reaction kinetics were evaluated for a fixed amount of catalyst (10 wt% related to the total mass of substrates) and a stirring speed (600 rpm) that was sufficiently high to avoid convective mass transfer limitations in the bulk phase. The temperature did not to influence the reaction rates and conversions above 90% were obtained for all temperatures after 12 h of reaction using a stoichiometric ratio (1:1) between the substrates. The prepared catalyst was recycled and reused in seven consecutive reactions of 8 h each and lost around 40% of its initial activity during the process. A Ping-Pong Bi–Bi kinetic model was proposed to represent the system reactions and was satisfactorily fitted to the experimental data.

Lipases are often used in immobilized form, but commercial immobilized lipases are costly. An alternative is to produce lipases in solid-state fermentation, dry the solids and then use the “dry fermented solids” (DFS) directly. We produced DFS by growing Burkholderia contaminans on a mixture of sugarcane bagasse and sunflower seed meal and used the DFS to esterify oleic acid with ethanol in subcritical and supercritical CO2 at 40 °C. Compared to a control without CO2 at atmospheric pressure, subcritical CO2 at 30 bar improved esterification activity 1.2-fold. Higher pressures, including supercritical pressures up to 150 bar, reduced activity to less than 80% of the control. At 30 bar, the esterification activity was improved a further 1.8-fold with the addition of 9% water (i.e. 9 g water per 100 g oleic acid) to the reaction medium. A subcritical CO2 atmosphere, with the addition of a small amount of water, improved the esterification activity of DFS containing lipases of Burkholderia contaminans.

An example of a sustainable and renewable but highly underused biomass with considerable potential as a source of a wide spectrum of valuable compounds is Arctium lappa, also known as burdock. In this work the feasibility and efficiency of advanced techniques applying compressed fluids to recover value from burdock seeds and roots was examined, and the influence of operating conditions and solvents on the yield, quality and composition of the extracts obtained was studied. For the seeds, compressed propane at two temperatures and pressures (6–20) MPa, and either neat supercritical CO2 (scCO2) or scCO2 with a co-solvent were tested. For the roots, extractions with scCO2 and different polarities co-solvents were performed at two temperatures and pressure 20 MPa. Pressurized liquid extractions with ethanol, methanol, water and methanol/water at 15 MPa and 353.15 K were also tested. The extracts obtained were evaluated by extraction yield, total phenolic content and antioxidant activity, and compared with Soxhlet with organic solvents. The rich spectrum of valuables - fatty acids and phenolics of different chemical complexities was identified and quantified applying GC-FID, GC–MS, LC – MS/MS. The results of this extensive study demonstrate that compressed fluids techniques are effective for value added product generation from burdock seeds and roots biomass.

Pressurized hot water extraction (PHWE), known as a “green” extraction technique, was used to obtain polysaccharide from the pulp of gabiroba (Campomanesia xanthocarpa Berg) fruits. The effects of pressure, temperature, and flow rate on pectin yields were analyzed through a full factorial design experiment 23. The optimal extraction conditions to achieve maximum pectin yield (5.70 wt%) were pressure of 150 bar, temperature of 120 °C, and flow rate of 1.5 mL min−1. The high pressure (100 bar) promoted an increase in galacturonic acid content (36.0%) compared to conventional hot water extraction (CEGP) with 25.7%. Differences in the proportion of homogalacturonan (HG) and rhamnogalacturonan (RG-I) domains ranging from 16.3 to 35.4% and 61.7 to 80.1%, respectively, were observed for each pectin sample according to the extraction conditions. The mono-dimensional (13C-NMR) and bi-dimensional (1H/13C HSQC-NMR) analyses confirmed the presence of HG and RG-I regions and indicated the presence of arabinogalactans type I (AG-I) and arabinogalactans type II (AG-II) in the PHWE pectin samples, which was not found for pectins from gabiroba pulp obtained by CEGP. The results showed that PHWE proved to be a promising method for extracting pectins from gabiroba fruits.

This work presents the processing of a high-acidity oil through sequential reactions of esterification using montmorillonite K10 and transesterification using zinc monoglycerolate. Since these solids had not been employed along with this approach beforehand, the objective of this work is to provide a general insight of the proposed process and demonstrate its technical feasibility. In this sense, the processing of a synthetic mixture containing soybean oil and lauric acid provided a reduction of the free fatty acid content from (40.8±0.1) % to (3.1±0.4) % after the esterification reaction and a fatty acid methyl ester yield of (95.4±0.2) % was obtained after the transesterification reaction. As compared to traditional homogeneous catalysts, the solid catalysts employed in this work require higher reaction times to achieve satisfactory ester yields but, on the other hand, they are less sensitive to the presence of both water and free fatty acids in the raw materials and can be easily recovered and reused. Therefore, the results accomplished may help the development of a technology for processing high-acidity fatty materials in order to obtain biodiesel, although its economic feasibility still needs a further assessment.

Arctium lappa is a perennial species of the Asteraceae family originally from Europe and Asia. Considered a weed species in the southern region of Brazil, it is popularly used as a natural anti-inflammatory. The complement system is an important component of the innate immune response. However, its exacerbated activation can lead to harmful conditions like autoimmune and inflammatory disorders. Plants that inhibit the activation of complement can be a promising tool in the treatment of inflammatory diseases. Here, we evaluated the effect of A. lappa leaves extracts on the activation of the classical and alternative pathways of complement system. Two extracts were obtained under supercritical conditions using scCO2 with ethanol as cosolvent, at 313.15K, 15 MPa (E1) and 25 MPa (E2). Classical and alternative activation were evaluated using complement fixation test. Different concentrations of A. lappa extracts E1 and E2 showed an inhibitory effect on both complement pathways, and heparin was used as control. The IC50 of E1, E2, and heparin were 28.26, 20.12 and 92.54 µg/mL for classical and 26.12, 27.70, 27.78 µg/mL for the alternative pathway. Results demonstrate that A. lappa is a promising complementary treatment for diseases associated with complement activation.

In this study, extraction yield of valuable compounds from brewer’s spent grain (BSG) using pressurized liquid extraction (PLE) was investigated varying temperature, solvent type, and flow rate at a constant pressure. The results were compared with Soxhlet extractions using the total phenolic compounds (TPC), total flavonoid compounds (TFC), antioxidant activity (AA), reducing sugars (RS), and total reducing sugars (TRS) as indices. The highest PLE extraction yield was 20.1 wt%, at 120 °C, 2 mL/min using ethanol to water volume ratio of 0.5, at 10 MPa. The TPC, TFC, and AA content were favored by water and water/ethanol extractions and temperature increase. The highest AA was obtained with water at 120 °C and 4 mL/min achieving 9944, 4769 and 4096 µmol TE/100 g of BSG extract, respectively. PLE was capable of present high extraction yields maintaining the RS and TRS in the BSG matrix. In addition, BSG was defatted with compressed propane before the extraction with PLE, showing that compressed propane is highly efficient in recovering the lipid fraction from BSG. The results demonstrated a great potential of water and different EtOH/Water solvent ratio at pressurized conditions for obtaining bio-compounds of BSG in a crude extract with expressive biological activity.

In this study, the extraction yield, the mathematical modeling of pressurized liquid extraction (PLE) kinetics with sub- and supercritical carbon dioxide (SC-CO2) of olive leaves (Olea europaea) and the biological activity of the extracts were evaluated. The extraction with PLE was conducted isobarically (10.3 MPa), varying the temperature (20, 40 and 60 °C) and the solvent (ethyl acetate, acetone, ethanol, ethanol:water—80:20, v:v), solvent flow (2 mL min−1) and time (110 min) and the extractions with SC-CO2, varying the temperature between 20 and 60 °C and the pressure between 8 and 25 MPa, keeping the time constant (210 min) and the CO2 flow of 2 mL min−1. In the extracts, antioxidant activity, total phenolic and flavonoid contents and oleuropein were evaluated. The highest total extract yield in the PLE was 30.91% at 60 °C, 10.3 MPa using ethanol:water (80:20, v:v). The yield obtained using the supercritical fluid was 0.68% at 60 °C and 25 MPa. The PLE extract obtained with ethanol at 60 °C presented the highest concentration of total phenolic content (386.42 mg GAE g−1 extract), total flavonoids content (33.43 mg CAT g−1 extract), oleuropein (73.65 mg g−1 extract) and antioxidant activity (82.87%). The overall extraction curves were modeled using the well-established Sovova model and kinetic extraction model based on the Brunauer–Emmett–Teller theory of adsorption. Both kinetic models used were able to correlate well with the experimental data with slightly better results obtained by the former. The alternative PLE extraction technique investigated in this work was found to be suitable for the extraction of olive leaves after short times of extraction obtaining an extract with high biological activities.

Hydrolysis of acid oils is an important alternative for the production of non-ionic surfactants and fatty acids that can be converted to fatty acid methyl esters (biodiesel) by esterification. In this work, hydrolysis of palm oil was initially carried out in subcritical water using zinc stearate as catalyst. The experiments were performed in a CSTR-type reactor where the effect of temperature (140–190 °C), palm oil-to-water MR (1:10–1:53) and catalyst amount (2–10 wt%) were evaluated. High contents of free fatty acids (up to 60 wt%) with 35 wt% diacylglycerols and 20 wt% monoacylglycerols were obtained. Also, zinc stearate maintained its catalytic activity for palm oil hydrolysis for five consecutive reuse cycles but changes in the catalyst chemical composition were observed, mostly due to the conversion of zinc stearate to zinc palmitate. However, by increasing the reaction time from 4 to 8 h at 190 °C, there was a decrease in the accumulation of free fatty acids and an increase in the accumulation of acylglycerols and this was a strong evidence for reaction reversion. After removal of water, palm oil hydrolysates still containing the reaction catalyst were subjected to simultaneous esterification and transesterification under similar reaction conditions, reaching a final monoester content of about 90 wt%. These values are 50 wt% higher than those obtained by direct transesterification using the same catalyst. Also, the resulting crude glycerin phase was colorless in appearance, indicating little contamination with reaction products and intermediates.

This work reports thermodynamic analysis of systems involved in the biodiesel production using ethanol at supercritical conditions. PC-SAFT equation of state was used from ASPEN Plus simulator for modeling all investigated systems. Binary and ternary phase equilibrium data at high pressure and temperature were used to assess the PC-SAFT capability of predicting the thermodynamic behavior of the complex mixture of interest in this work. The results showed that the PC-SAFT is a reliable tool to represent the phase behavior of mixtures involving ethanol, vegetable oil, fatty acid, ethyl esters of fatty acid and glycerol. Phase behavior of the reaction system was evaluated under specified experimental conditions and considering different reaction conversions. Pressure-temperature diagrams demonstrated that the two-phase region for the reaction mixture decreases as the extension of reaction is increased. The PC-SAFT equation of state was used to estimate the density of the reactant mixture and the effect of this parameter over the residence of the reaction was assessed, where it was clearly demonstrated that the density of the mixture greatly affects the residence time calculation for the reactions of biodiesel production at high pressure conditions.

Extraction efficiency of bioactive compounds from yacon leaves using supercritical CO2 + ethanol (scCO2+EtOH) fluid extraction and a conventional method were investigated. scCO2+EtOH runs were performed under the following conditions: 30–70 °C, 15–25 MPa and varying the ethanol (co-solvent) to solid (raw material) mass ratio (MR). All extractions were evaluated in terms of overall extraction yield (X0), fatty acid composition, total phenolic content (TPC) and antioxidant activity (AA). Results indicated that scCO2+EtOH presented the highest extraction yield 5.22 wt% at 70 °C/25 MPa/MR 3:1. High values of TPC and AA were found in all extracts. Major unsaturated fatty acids found in yacon leaves extracts were gamma-linolenic (ω-6), eicosapentaenoic (ω-3) and linoleic (ω-6) acids. The highest ω-6/ω-3 fatty acids ratios were found in the extracts obtained using scCO2+EtOH.

In this work, benzyl butyrate was synthesized for the first time via biotechnological esterification of benzyl alcohol and butyric acid in a solvent-free system (SFS). The synthesis was maximized in batch reactors, considering a low substrates molar ratio of 1:1. Novozym 435, a well-known commercial immobilized lipase (Candida antarctica fraction B - Cal B), was the best biocatalyst in the benzyl butyrate synthesis reaching 80% of conversion, followed by the NS 88011, a new lipase prepared with low-cost non-commercial material (Cal B) (46% of conversion). The butyric acid acted as an enzyme deactivator and the excess of alcohol played an important role in the performance of the immobilized enzymes. A fed-batch strategy was employed to overcome the drawbacks related to the use of alcohol in excess, and the results showed that the Novozym 435 had the activity preserved over many cycles of esterification. The scale-up of the fed-batch reactor showed that Novozym 435 had a good and viable performance in the benzyl butyrate esterification at a molar ratio of 1:1 and SFS.

A single-cell segregated solver for calculating the behavior of carbonated brine injection in carbonate rocks aiming at carbon geological storage is presented. The approach is designed to represent an element in computational fluid dynamics simulations and enhance customization to include dissolution chemistry by integrating a CO2 solubility model, speciation calculations, mineral dissolution reactions and the consequent change in reservoir properties over time. The equilibrium and dissolution reactions are calculated sequentially, where an adaptive control of the time step ensures that the dissolution rate is computed from the correct equilibrium condition. A pseudo-homogeneous medium represents the reservoir, where alterations in rock structure are computed via a formulation based on Kozeny-Carman. Finally, a stabilization algorithm based on the Bjerrum plot of H2CO3 provides numerical robustness for the speciation calculations. The results can estimate the time frame for the system to reach equilibrium and the corresponding changes in rock structure. The solubility model was validated against experimental data, while the speciation model was compared to more rigorous thermodynamics models such as electrolyte-NRTL and Pitzer, showing minor differences. The algorithm as a whole provides similar results for the pH when compared to a state-of-the-art single-cell model with an extensive chemical system for a real reservoir, proving it can be a viable option for numerical simulations.

Optimal control of substrate feed rate in glycerolysis of vegetable oils was studied as a tool to improve monoacylglycerols (MAG) and diacylglycerols (DAG) production. Stochastic optimization strategy (Differential Evolutionary algorithm) was used to deal with the high complexity of the enzyme-catalyzed reactions dynamic behavior. Depending on the reaction system, optimal control of glycerol feed rate into the reaction showed to avoid enzymatic inhibition by the glycerol and improve acylglycerols yields up to 50% when compared to batch system. The obtained results showed that optimal control strategy can be used as an efficient tool to maximize the amount of desired product obtained by enzyme-catalyzed glycerolysis, particularly when the biocatalyst activity is significantly affected by substrate concentration.

This work reports phase equilibrium measurements and thermodynamic modeling of the binary systems (CO2 + ethyl levulinate) and (CO2 + levulinic acid). Each composition was carried out in a high-pressure variable-volume view cell at temperatures ranging from 303.15 to 353.15 K and with CO2 mole fraction ranging from 0.4002 to 0.9751 for the system (CO2 + ethyl levulinate) and from 0.4083 to 0.9930 for the system (CO2 + levulinic acid). Under these conditions, only vapor–liquid phase transitions were observed. The experimental data were modeled with the Peng–Robinson cubic equation of state with the Boston–Mathias alpha function (PR-BM) and using the van der Waals quadratic mixing rule. The results showed that the experimental data of the system (CO2 + ethyl levulinate) were adequately represented by the thermodynamic model with a unique set of binary interaction parameters, which were fitted from all isotherms. Whereas the experimental data of the system (CO2 + levulinic acid) were only adequately represen...

This study reports results of an entire green methodology combining bioreduction by baker’s yeast supported cells and a medium formed by glycerol and scCO2 to a β-ketoester biotransformation. Fermented cells of Saccharomyces cerevisiae, immobilized in calcium alginate beads, were chosen to catalyze ethyl acetoacetate reduction in a biphasic system of scCO2 and glycerol 20% (vol/vol) (T = 45 °C and P = 100 bar). The bioreduction was also carried out at normal conditions (T = 45°C and P = 0.92 bar) in n-heptane and glycerol 20% (vol/vol). Using scCO2/glycerol the reaction reached 77% of conversion in 6 h, and the enantiopure (S)-ethyl-3-hydroxybutyrate (enantiomeric excess > 99%) was observed as the unique product. The same reaction under normal conditions led to only 12% conversion in 6 h. The approach evaluated in this study showed a great potential to be employed as a greener alternative to conventional bioreduction process.

Objective: Biodiesel is a renewable fuel considered as the main substitute for fossil fuels. Its industrial production is mainly made by the transesterification reaction. In most processes, information on the production of biodiesel is essentially done by off-line measurements. Methods: However, for the purpose of control, where online monitoring of biodiesel conversion is required, this is not a satisfactory approach. An alternative technique to the online quantification of conversion is the near infrared (NIR) spectroscopy, which is fast and accurate. In this work, models for biodiesel reactions monitoring using NIR spectroscopy were developed based on the ester content during alkali-catalyzed transesterification reaction between soybean oil and ethanol. Gas chromatography with flame ionization detection was employed as the reference method for quantification. FT-NIR spectra were acquired with a transflectance probe. The models were developed using Partial Least Squares (PLS) regression with synthetic samples at room temperature simulating reaction composition for different ethanol to oil molar ratios and conversions. Model predictions were then validated online for reactions performed with ethanol to oil molar ratios of 6 and 9 at 55ºC. Standard errors of prediction of external data were equal to 3.12%, hence close to the experimental error of the reference technique (2.78%), showing that even without using data from a monitored reaction to perform calibration, proper on-line predictions were provided during transesterification runs. Results: Additionally, it is shown that PLS models and NIR spectra of few samples can be combined to accurately predict the glycerol contents of the medium, making the NIR spectroscopy a powerful tool for biodiesel production monitoring.

Experimental phase equilibrium data for the pseudoternary system involving (carbon dioxide + ω-pentadecalactone + dichloromethane) have been measured in order to provide fundamental information to conduct the polymerization reaction in supercritical carbon dioxide medium. The experiments were performed using a variable-volume view cell over the temperature range from 313 K to 343 K, system pressure between 3.6 MPa and 19.4 MPa and different mass ratios of dichloromethane to ω-pentadecalactone (0.5:1, 1:1 and 2:1). Phase transitions of vapour-liquid (bubble and dew point), liquid-liquid and vapour-liquid-liquid types were observed. The experimental results were modelled using the Peng-Robinson (PR) equation of state with the Wong-Sandler (PR-WS) mixing rule, providing a good representation of the experimental phase equilibrium data.

Valeric biofuels are renewable and environmental friendly fuels whose production avoids the competition with the food industry for edible oils since its route of production uses lignocellulose of residue from crops as raw material. After the reaction steps several purification operations are necessary for the valeric biofuels to meet purity standards. Therefore, it is of utter importance the knowledge of both liquid-liquid (LLE) and vapor-liquid (VLE) equilibrium behavior of species present in the process, such as ethyl valerate, valeric acid, ethanol and water. In this sense, the objective of this work is to provide a general overview for the phase equilibria of the system aforementioned using experimental data collected as background for the thermodynamic modeling. Experimental data concerning to LLE were evaluated at local atmospheric pressure (around 90.9 kPa) and 293.15 K and 318.15 K, while VLE data were collected at several different controlled pressures, ranging from approximately 7 kPa to local atmospheric pressure (around 91 kPa). UNIFAC and PC-SAFT (Perturbed Chain form of the Statistical Associating Fluid Theory) were used to perform the thermodynamic modeling. The results obtained in this work are helpful to prove the importance of carefully evaluate the interactions between the molecules present in the system. Otherwise, the design of unit operations could underestimate the number of stages required for the purification, causing the products to not reach purity specifications.

This study reports the extraction of Arctium lappa leaves using scCO2 with ethanol as solvent (scCO2+EtOH) aiming the recovery of bioactive components. Experiments were performed varying the temperature (313.15–353.15 K), pressure (15–25 MPa), and ethanol to CO2 mass ratio in the static extraction step, where extraction yield, chemical composition, phenolic total content (TPC), antibacterial and antioxidant activity were determined. GC analysis showed diisooctyl phthalate, amyrin acetate, lupeol acetate and phytol as major compounds. It was observed the best relation between maximum yield (6.09%) and biological activities for the extract obtained at 353.15 K and 15 MPa. High values of antioxidant activity were found for the extracts obtained at 353.15 K and 15 MPa determined by the DPPH method and the phosphomolybdenum reduction method. The same extract presented the high phenolic content (35.51 mgGAE/gextract). High antibacterial activity was observed for all the extracts obtained with scCO2+EtOH against Staphylococcus aureus.

This work aimed to investigate the optimum conditions of pressure, temperature, ultrasound intensity, solvent concentration and solvent flowrate of ultrasound-assisted pressurized liquid extraction of anthocyanins from Aronia melanocarpa pomace. The novel setup operates with an aqueous solution of citric acid as extraction solvent. The optimization was performed in order to maximize the total anthocyanins content extracted from the pomace. The optimized conditions of 70 °C, 180 bar, a solvent concentration of 1.5 % wt. citric acid, in a 200 W ultrasound bath were obtained. These conditions resulted in 88.0 % wt. extraction of anthocyanins in 45 min. A kinetic study was performed to study the influence of the temperature on the total anthocyanin yield obtained at the optimal extraction conditions. Moreover, the component stability was assessed to prove that the system could successfully operate at 80 °C. Compared to classical batch extraction using the same solvent concentration and feedstock, the total anthocyanin content of the extract was increased by 19%.

Oils enriched with diacylglycerol have received a great deal of attention due to their potential health benefits when used as a replacement for conventional edible oils. This work reports experimental results and thermodynamic modeling of liquid-liquid equilibrium of systems containing mono-, di- and triacylclycerols from olive oil, glycerol and isopropanol. The UNIQUAC model was used in the description of phase equilibria, which was well fitted to experimental data with root mean square deviations equal or lower then 1.4 wt% for the all studies systems. The results presented in this work show the feasibility of diacylglycerol separation from other acylglycerols through liquid-liquid extraction using glycerol and isopropanol as solvents.

Lignocellulosic biomasses are primarily composed of cellulose, hemicelluloses and lignin and these biopolymers are bonded together in a heterogeneous matrix that is highly recalcitrant to chemical or biological conversion processes. Thus, an efficient pretreatment technique must be selected and applied to this type of biomass in order to facilitate its utilization in biorefineries. Classical pretreatment methods tend to operate under severe conditions, leading to sugar losses by dehydration and to the release of inhibitory compounds such as furfural (2-furaldehyde), 5-hydroxy-2-methylfurfural (5-HMF), and organic acids. By contrast, supercritical fluids can pretreat lignocellulosic materials under relatively mild pretreatment conditions, resulting in high sugar yields, low production of fermentation inhibitors and high susceptibilities to enzymatic hydrolysis while reducing the consumption of chemicals, including solvents, reagents, and catalysts. This work presents a review of biomass pretreatment technologies, aiming to deliver a state-of-art compilation of methods and results with emphasis on supercritical processes.

Este estudo apresenta as extracoes de folhas de yacon usando fluido supercritico CO 2 + etanol (scCO 2 +EtOH). Ensaios foram realizados sob as seguintes condicoes: 30-70 oC, 15-25 MPa e variando a razao massica de etanol (co-solvente) para solido (materia prima) RM. Todas as extracoes foram avaliadas em termos de rendimento total de extracao (X 0 ) e as cineticas de extracao foram apresentadas. Os extratos foram obtidos satisfatoriamente usando a tecnologia supercritica. O rendimento variou de 2,32 % usando scCO 2 +EtOH a 30oC/ 25 MPa/ RM 1:1 ate 5,22 % a 70 oC/ 25 MPa/ RM 3:1.

Edible oils enriched with diacylglycerols are promising choices for healthy cooking oils, and for that reason production and separation processes regarding these molecules have received great attention. This work reports experimental results and thermodynamic modelling of liquid-liquid equilibrium of systems containing glycerolized olive oil (source of triacylglycerols, diacylglycerols, monoacylglycerols and free fatty acids), glycerol and ethanol. The LLE experimental data were used to estimate UNIQUAC binary interaction parameters. The mathematical model calculated the liquid phase’s compositions by minimizing the Gibbs free energy of the system, using a combination of stochastic and deterministic optimization methods in order to avoid local minima. The model was well fitted to the experimental data, with a root mean square deviation of 1.43 wt% between experimental and calculated data. The results indicate the feasibility of diacylglycerol separation from other triacylglycerols and free fatty acids through liquid-liquid phase separation using glycerol and ethanol as solvents.

Process optimization for producing diacylglycerol-enriched oils has received great attention due the importance of these products for healthier and more balanced diets. This work reports experimental data of liquid-liquid phase equilibrium of hydrolyzed olive oil (which comprises on its composition triacylglycerols, diacylglycerols, monoacylglycerols and free fatty acids) with ethanol and water, and subsequent analysis of oxidative stability of the oil obtained from the liquid phases. Liquid-liquid equilibrium experimental data obtained were modeled using the UNIQUAC thermodynamic model, which was well fitted to experimental data with a root mean square deviation of 1.76 wt%. The results obtained demonstrated the potentiality of liquid-liquid extraction as a suitable procedure for olive oil enrichment in diacylglycerol, after a hydrolysis procedure. It was also observed that liquid-liquid phase separation has a significant effect on the content of important antioxidants present in the olive oil, what affects the oxidative stability of the samples submitted to the liquid phase extraction. From the results obtained in this study, it has been also noticed that the acylglycerols and free fatty acids profile in of the oil samples presented a major rule on their stabilities.