•Sorption isotherms were successfully fitted by the GAB equation.•Drying kinetics was successfully predicted by one-parameter fitted equation.•Conveyor belt drying reduced moisture to suitable levels ...for supercritical extraction.•Drying at 60°C for 60min was best for extraction yield and preserving compounds.•Using ethanol as a co-solvent enhanced the concentration of bioactive compounds.
Eugenia uniflora L. leaves were dried in a conveyor-belt dryer to assess the influence of drying conditions (air temperature and number of passes/residence time in the dryer) on the yield, composition, antioxidant activity and concentration of phenolic compounds found in the extracts obtained from supercritical extraction. An analysis of leaf drying in the conveyor belt was carried out by investigation of sorption isotherms and drying curves obtained under air temperatures of 50, 60 and 70°C. The sorption curves were fitted to the GAB thermodynamic model and the drying curves to a one-parameter empirical equation. The fitted equations were effective to predict the discharge moisture as function of the residence time under different temperatures. The samples for extraction were dried under 50°C/120min, 60°C/60min and 70°C/60min and their moisture levels were reduced respectively to 15wt.%, 10wt.% and 6wt.%. The extractions were carried out at 80°C and 250bar using as solvents either the pure supercritical CO2 or a mixture of ethanol and supercritical CO2 at a mass ratio of 0.5:1. The higher extraction yields (9.9±0.1wt.%), phenolic content (85±2mg GAE/g extract) were found in the extracts from samples dried under 60°C/60min using ethanol as a co-solvent in extraction.
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In this work was presented a sequential strategy to optimize and scale-up the production of ethanol by solid-state saccharification and fermentation using rice bran as substrate. In the first step, ...fermentation was carried out in Erlenmeyers to study the influence of eight variables by means of a Plackett Burman design. After the choice of most significant ones, a central composite rotational design (CCRD) for three independent variables (rice bran concentration, moisture content and inoculum size) was conceived to optimize the ethanol production in a packed-bed bioreactor. From Erlenmeyers to packed bed bioreactor the process was scaled-up 10 times. Maximum ethanol production in the packed-bed bioreactor was 135 ± 10.8 g kg−1 at inoculum size, rice bran concentration and moisture content of 10% v/v, 62.5% w/w and 65% w/w, respectively. The ethanol yield obtained in the packed-bed bioreactor was similar to that in the erlenmeyers flasks (138.7 g kg−1), validating the strategy adopted for optimization and scale-up.
•Production of ethanol by solid-state saccharification and fermentation.•Maximum ethanol production was 135 g kg−1.•Production comparable with liquid media containing high-solid loading.
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•Senecio brasiliensis extracts were obtained using supercritical carbon dioxide.•The highest yield was obtained at higher pressure (25 MPa) and lower temperature ...(40 °C).•Integerrimine, elemene and germacrene-D were the major compounds identified.•Sovová’s model was successfully applied to the extraction curves.
Senecio brasiliensis aerial parts extracts were obtained using supercritical carbon dioxide (SC-CO2) extraction. The objective was to evaluate the effects of temperature and pressure on the yield, extraction kinetics, and chemical composition. The extractions with SC-CO2 were performed at 15, 20 and 25 MPa, and 40, 50 and 60 °C. Soxhlet method was used as a comparative method to SC-CO2 and the compounds were analyzed by gas chromatography-mass spectrometry. Sovová’s model was fitted to SC-CO2 extraction data in order to describe the kinetic extraction curves. When using SC-CO2, the highest yield was obtained from leaves (1.76 wt.%) at 25 MPa and 40 °C. The major compounds identified from all matrices were alpha-humulene, germacrene-D, sphathulenol, squalene, tricosane, pentacosane, and dotriacontane. Compounds such as integerrimine, elemene, and caryophyllene were also found in extracts obtained from leaves and flowers. SC-CO2 demonstrated to be an efficient technology for the extraction of bioactive compounds from Senecio brasiliensis.
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•Olive leaves were dried in a conveyor belt dryer aimed at supercritical extraction.•Influence of drying conditions on extraction was investigated.•Leaf temperature and output ...moisture were successfully predicted by a drying model.•Higher extraction yields and AA were found in samples dried at 50 °C for 300 min.•Total phenolic compounds content was enhanced in samples dried at 70 °C for 60 min.
The influence of drying conditions on the composition of supercritical extracts recovered from olive leaves was investigated. Leaves were dried on a conveyor belt and the effects of air temperature and residence time on the extraction kinetics, global yield, antioxidant activity, total polyphenols content and chemical profiles of the extracts were evaluated. Inlet air temperatures of 50, 60 and 70 °C with residence times of 180, 120 and 60 min, respectively were tested. A model based on mass and energy balances with effective heat and mass transfer coefficients fitted from experimental data was used to describe the drying process. The temperature and output moisture of the leaves were well predicted by the model. The extraction kinetics was not significantly affected by the drying conditions (air temperature and residence time), but the extraction yield was enhanced for samples dried at 50 °C/180 min whereas the higher values of antioxidant activity and phenolic contents were found at 60 °C/120 min. Sovová’s model was effective in describing the supercritical extraction of olive leaves and can be used to estimate the extraction kinetics and mass transfer coefficients.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The aim was to investigate the enzymatic saccharification and fermentation for ethanol production. The rice bran, inoculum, corn steep liquor, soybean bran, amylase, cellulase concentrations and time ...of inoculum addition were evaluated using a Plackett-Burman (PB) experimental design. Furthermore, a central composite rotational design (CCRD) for three independent variables was carried out to optimise the ethanol production. Inoculum was added after 18 h of enzymatic hydrolysis and all the process was carried out at 35 °C during 48 h. Maximum ethanol production was 175 ± 5.8 g kg−1 obtained at 15% (m/m) concentration of inoculum, 150 g l−1 of rice bran and 3% (m/m) of cellulase. Rice bran is therefore a promising raw material for ethanol production.
•Constant temperature for hydrolysis and fermentation.•Conversion of 84% of fermentable sugar to ethanol.•Yield of 175 g of ethanol per kg of rice bran.
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This paper investigated different strategies to prevent salt deposition during weak black liquor (WBL) desalination under hydrothermal liquefaction conditions based on phase behaviour analysis. Phase ...equilibria of model salt solutions replicating the WBL composition were studied by high-pressure differential scanning calorimetry (HP-DSC) and different strategies to induce the Type 1 salt behaviour were applied. Two strategies led to an optimised salt separation: adjusting the concentrations of Type 1 salts, NaOH and NaHS, present in the WBL, and selectively exchanging carbonate from the model salt solution by replacing it with hydroxide. These strategies were tested in PSI’s continuous salt separation test rig, considering the recovering of salts. Although increasing the concentration of the Type 1 salts (NaOH and NaSH) impacted the precipitation temperature and extent of the salts, the strategy was not able to prevent it entirely. The HP-DSC results confirmed the efficiency of carbonate replacement by hydroxide since the Type 1 behaviour was observed after exchanging 75% of the carbonate. In the presence of organics, some salt accumulation and overflow into the desalinated stream occurred, which was addressed by optimising the brine flow rate.
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•HP-DSC as a tool for identifying the phase behaviour of salts mixtures from black liquor.•Type 1 salt behaviour is observed after removing 75% of carbonate from the black liquor model.•75% carbonate reduction ensures continuous salt separation, allowing HTL/HTG operation.•Doubling Type 1 salts prevents clogging, but does not prevent the accumulation of salts.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•Supercritical extraction at 250 bar and 80 °C led to the highest global extraction yield.•67 % to 92 % of the extracted mass was recovered before the end of the constant extraction ...rate period.•Sovová’s model was effective in describing the overall extraction curves.•COM can be reduced by increasing the production scale.
Extracts from Eugenia uniflora L. (pitanga) leaves grown in the Brazilian tropical savanna were obtained by supercritical CO2. The influence of temperature (40, 60 and 80 °C) and pressure (15, 20 and 25 MPa) on the extraction yield, overall extraction curves, kinetic parameters, chemical profiles, antioxidant activity, and total phenol content were evaluated. Amongst the conditions investigated, the highest global extraction yield (7.9 wt%) was found at 80 °C and 25 MPa, whereas the highest antioxidant activity (52.9 ± 0.9 %) and total phenol content (63.6 ± 4 mg GAE/g of leaves) were obtained at 40 °C and 25 MPa. Selina-1,3,7(11)-trien-8-one, oleic acid, phytol, and γ-sitosterol were the main compounds found in pitanga leaves extracts. The overall extraction curves showed that in most conditions, 67–92% of the extracted mass was recovered before the end of the constant rate extraction period. To estimate the cost of manufacturing (COM) of pitanga leaves extracts, the extraction process was simulated using the SuperPro Designer 8.5®. For extraction at 40 °C/25 MPa, the COM was US$ 654.90/kg, while for extraction at 80 °C/25 MPa, the COM was US$ 475.35/kg, both results for scale production of 100 L.
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Lignin is a promising resource for the sustainable production of platform chemicals and biofuels. The paper industry produces large quantities of lignin every year, mostly dissolved in a black ...liquor. With the help of hydrothermal liquefaction, black liquor can be used directly as a feedstock to depolymerize the lignin to desired products. However, because various cooking chemicals (e.g., NaHS, NaOH) used in the Kraft process, dominant in the paper industry, are also dissolved in the black liquor, it is necessary to study in detail their influence on the process as well as their fate. In this work, the focus was on the fate of sulfur and the influence of sulfide (HS–). For this purpose, hydrothermal liquefaction experiments (250–400 °C) were carried out with black liquor and self-prepared model black liquor with different sulfide concentrations (0–3 g·L–1 HS–) in batch reactors (V = 25 mL), and the products were analyzed to understand the chemical pathways involving sulfur. It was found that the inorganic sulfur compounds react with organic matter to produce organic sulfur compounds. Dimethyl sulfide is the most abundant of these products. The HS– concentration correlates with the amount of dimethyl sulfide produced. Because methanethiol has also been qualitatively detected, the reaction mechanism of Karnofski et al. for the formation of dimethyl sulfide in the Kraft process also applies to the hydrothermal liquefaction of black liquor. Increased sulfide concentration in the feed leads to an accelerated depolymerization of lignin. In contrast, the yields of some aromatic monomers decrease slightly, possibly as a result of repolymerization reactions also occurring more quickly.
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•Pecan nut cake has a large amount of oil (54 %).•Pecan nut cake oil was recovered using compressed CO2 and compressed LPG.•The highest yield (56.33 %) was obtained with compressed ...LPG extraction.•Oil was predominantly comprised of unsaturated fatty acids (UFA≅93 %).•Significant contents of squalene and β-sitosterol were also obtained.
Pecan nut cake (PNC) is residual biomass obtained as a result of cold pressing of pecan oil. PNC oil extractions using compressed carbon dioxide (C−CO2) and compressed liquefied petroleum gas (C-LPG) were performed. The influence of extraction parameters such as pressure (15–25 MPa – C−CO2; 1–2.5 MPa – C-LPG) and temperature (20–60 °C – C−CO2; 20–40 °C – C-LPG) on the extraction yields and chemical profile were determined. The higher yields were achieved at 25 MPa / 20 °C (C−CO2) and 1 MPa / 20 °C (C-LPG). The chemical profile of oils is mainly characterized by fatty acids where the oleic and linoleic acids were the majority compounds found in all samples. Contents of squalene and β-sitosterol also were obtained in the oils. The results showed that PNC is interesting biomass for oil extraction and which separation processes using compressed fluids is an attractive option for processing it.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The excessive consumption of plastic packaging and its consequent disposal and accumulation in the environment have aroused the interest of researchers in developing packaging that can cause less ...harm to nature. In this sense, this article presents research on the addition of antioxidant extracts from pecan nut cake in biodegradable packaging made with a polymeric mixture of gelatin and corn starch. The films produced were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, thickness, mechanical properties, water vapor permeability (WVP), solubility, water contact angle, optical properties, in vitro bioactive activity, and biodegradability. A higher concentration of total phenolic compounds (101.61 mg GAE/g) was found for the condition where alcohol content and extraction time were 65% and 20 min, respectively. Pecan nut cake (PNC( extracts did not influence the film's tensile strength, and elongation at break was tightly increased by adding 10-20% extracts. The film's characterization pointed to more than 67% solubility, and adding PNC extract implied more hydrophilic surfaces (contact angles lower than 65°). Furthermore, the film opacity showed a linear relation with PNC extract concentration, and a higher luminosity (L*) was observed for the film without extract. Furthermore, the antioxidant activity of the films was enhanced with the addition of PNC extracts, and complete biodegradation was observed until the ninth day. Therefore, biodegradable films prepared from a mixture of gelatin starch and enriched with PNC extracts showed excellent mechanical properties and potential as carriers of antioxidant compounds, allowing us to propose their use as active packing.
