In this study, the extracted oil of Pistacia lentiscus L. the Tunis region was extracted using supercritical carbon dioxide (SC-CO2) extraction containing different major components in the oil such ...as α-pinene (32%) and terpinene-4-ol (13%). The investigation of the effect of different variables on the extraction yield with 5% level of confidence interval showed that the CO2 pressure was the main significant variable to influence the oil yield. In order to better understand the phenomena, three parameters were considered to adjust all parameters of broken and intact cell (BIC) model: grinding efficiency (G), the internal mass transfer parameter ( k S a 0 ), and the external mass transfer parameter ( k f a 0 ), which were estimated by experimental extraction curves to calculate the diffusion coefficient. From an economic point of view, we found out that the high cost of production of the extracted oil was due to the low mass of extracted oil obtained from this type of plant.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The nanofluids containing more two different types of nanoparticles with suspension of base fluids is referred to hybrid nanofluids. The modified class of hybrid type nanomaterials is new impressive ...category of nanofluid model which obtained with suspension of base fluid into more than two different types of nanoparticles. The heating influence and capacitance of modified hybrid nanoparticles is more impressive as compared to hybrid model and traditional nanofluid model. Following such motivations in mind, current exploration reports the comparative thermal inspection of three types of nanoparticles like aluminium oxide (Al2O3), silicon dioxide (SiO2) and titanium dioxide (TiO2) with suspension of base particles along with ethylene glycol (C2H6O2) base fluid. The flow pattern for such nanoparticles flow is observed due to curved surface comprising the stagnation point flow. The Casson fluid model is used to identify the rheological impact and base fluid characterization. The nonlinear radiation impact is also utilized to modify the model. The Keller box numerical outcomes against the developed set of equations are obtained. A comparative investigation for the suspension of modified hybrid nanomaterial (Al2O3+SiO2+TiO2−C2H6O2) is inspected.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
Fluids have played and still play a vital role in attaining an optimized output from industrial processes. However, due to technological advancement, fluids with high hydrothermal characteristics are ...required. In order to overcome these challenges, researchers have developed fluids with dispersed nanoparticles, which are recognized as nanofluids. Various types of nanoparticles can be added to base fluids to produce thermally enhanced liquids. Among these, the addition of multi-walled carbon nanotubes (MWCNTs) is considered the best due to the considerable enhancement of thermophysical properties and the stability of the solution. Thus, in the present investigation, an analysis of the heat transfer characteristics of an MWCNT–water nanofluid included in a star-shaped cavity equipped with a hot rectangular baffle is conducted. In addition, a uniform magnetic field is applied along the x-direction to oppose the convective flow generated by variations in density. Mathematical formulations under assumed boundary conditions and physical assumptions are established in the form of dimensionless PDEs. The finite-element-method-based software “COMSOL” is used to execute the numerical simulations. PARADISO is employed to resolve the developed non-linear system of equations. The effects of the governing parameters on the velocity and temperature fields are presented through streamlines and isotherms. The Nusselt number is evaluated to depict the impact of the addition of nanoparticles (MWCNTs) on the heat transfer enhancement. Changes in the horizontal and vertical components of velocity are also evaluated against the Rayleigh number and nanoparticle volume fraction via cutline representation.
The olive growing in Tunisia has an economic dominance and agricultural importance. However, the huge extraction of olive oil generates a large quantity of olive mill wastewater (OMW), which is ...discharged to the surroundings. The highly polluting potential (organic load) of OMW threatens the environment and requires an urgent solution. Supercritical fluid extraction (SFE) is a green extraction method that can be applied to purify OMW and, at the same time, to isolate a high quality oil from this wastewater.
In order to explore and to valorize the compositions of Olive mill wastewater (OMW), extraction in different solvents (supercritical CO2, hexane) was carried out and chemical composition of the extracted oils were established by GC-FID. The Tunisia OMW were collected from two different zones namely Sousse and Sfax.
In this work, we have investigated the effects pressure (P) and temperature (T) on the yield and the quality of oil. The suitable conditions for the extraction of oil from lyophilized OMW by Supercritical carbon dioxide (SC-CO2) were found to be the pressure of 30 MPa and the temperature of 60 °C. In order to simulate the process, the model of broken and intact cells (Sovova’s model) was applied. The model well represented the experimental data.
Oil yields ranged from 21.3 % to 33.87 % depending on the extraction solvent used. Monounsaturated fatty acids (MUFA) were the major compounds of the oils, based on the fatty acid analysis. Chromatographic analysis revealed that the chemical compositions vary from one region to another, extraction solvent as well as the conditions of pressure and temperature.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Previously, the exopolysaccharides produced by Lactiplantibacillus plantarum C7 isolated from the broiler intestine have been shown to possess probiotic potential. In this study, we highlighted the ...capacity of this strain to produce exopolysaccharide (EPS) endowed with several biological activities. The 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) free radical scavenging activities of EPS were found to be 30.4% and 68.165%, respectively, at 100 mg/mL. The ferrous reducing potential of EPS was measured to be 25.26%. Furthermore, EPS exhibited antibacterial effects against both Gram-negative and Gram-positive pathogens, including Escherichia coli ATCC 10536 and Bacillus cereus ATCC 11778, with inhibition zones of 22.5 ± 0.70 mm and 20 ± 1.41, respectively. On the other hand, the exopolysaccharide also exhibited excellent inhibitory activity against butyrylcholinesterase (BChE), achieving 70.99% inhibition at a concentration of 10 mg/mL. FTIR spectra were used to characterize functional groups in EPS. Our findings proved that EPS from Lactiplantibacillus plantarum C7 could be explored for various applications, particularly in the health and functional food sectors.
Kinetic modeling of biomass and lactic acid production by Enterococcus faecalis SLT13 have been developed during batch culture in M17 and Hydrolyzed Cheese Whey (HCW) in 2 L and 20 L bioreactors. The ...specific growth rate μmax was higher in 20 L bioreactor (1.09 h−1); however, the maximum specific lactic acid production rate qpmax and maximum specific sugar utilization rate qsmax were higher in 2 L bioreactor. Biomass and sugar utilization were affected by lactic acid inhibition in HCW. No effects of substrate inhibition have been observed. Substrate limitation of biomass has been observed on HCW in 20 L bioreactor; the substrate limitation constant for biomass Ksx was 4.229 g/L. Substrate limitation of sugar consumption has been observed on M17 in 2 L bioreactor; the substrate limitation constant for sugar consumption Kss was 2.73 g/L. Compared to experimental data, the model provided good predictions for biomass, sugar consumption, and lactic acid production.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
A cooling system with impinging jets is used extensively in diverse engineering applications, such as solar panels, electronic equipments, battery thermal management, textiles and drying ...applications. Over the years many methods have been offered to increase the effectiveness of the cooling system design by different techniques. In one of the available methods, nano-jets are used to achieve a higher local and average heat transfer coefficient. In this study, convective cooling of double rotating cylinders embedded in a porous medium is analyzed by using hybrid nano-jets. A finite element formulation of the thermo-fluid system is considered, while impacts of Reynolds number, rotational speed of the double cylinders, permeability of the porous medium and distance between the cylinders on the cooling performance are numerically assessed. Hybrid and pure fluid performances in the jet cooling system are compared. It is observed that the cooling performance improves when the rotating speed of the cylinder, permeability of the medium and jet Reynolds number are increased. The heat transfer behavior when varying the distance between the cylinders is different for the first and second cylinder. Higher thermal performances are achieved when hybrid nanofluid with higher nanoparticle loading is used. An optimization algorithm is used for finding the optimum distance and rotational speeds of the cylinders for obtaining an improved cooling performance, while results show higher effectiveness as compared to a parametric study. The outcomes of the present work are useful for the thermal design and optimization of the cooling system design for configurations encountered in electronic cooling, energy extraction and waste heat recovery.
Hydroxytyrosol (HXT) (also known as 3,4-dihydroxyphényléthanol,) is a biophenol extracted from olive. HXT is known for its high antioxidant significance effect. In this work, we focused on the study ...of the behavior of the solubility of HXT in binary solvent mixtures (ethanol + water) as well as the thermodynamic proprieties. The solubility of HXT in water, ethanol and in binary solvent mixtures (ethanol + water) was measured at five different temperatures from (293.15 to 318.15) K. The enthalpy of fusion and the melting point of HXT were experimentally determined since they are essential for the study of the of solubility and crystallization process. Thermodynamic properties of dissolution of the HXT (Gibbs energy (ΔsolG°), molar enthalpy of dissolution (ΔsolH°), and molar entropy of dissolution (ΔsolS°)) are predicted using the van’t Hoff analysis, the Gibbs equation, and the measured solubilities data. The preferential solvation has been determined using the inverse Kirkwood–Buff integral (IKBI) theory.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The equilibrium solubility of amygdalin in ethanol (1) + water (2) mixtures at 293.15 K to 328.15 K was reported. The thermodynamic properties (standard enthalpy ΔsolnH°, standard entropy ΔsolnS°, ...and standard Gibbs energy of solution ΔsolnG°) were computed using the generated solubility data via van’t Hoff and Gibbs equations. The dissolution process of amygdalin is endothermic and the driving mechanism in all mixtures is entropy. Maximal solubility was achieved in 0.4 mole fraction of ethanol at 328.15 K and the minimal one in neat ethanol at 293.15 K. Van’t Hoff, Jouyban–Acree–van’t Hoff, and Buchowski–Ksiazczak models were used to simulate the obtained solubility data. The calculated solubilities deviate reasonably from experimental data. Preferential solvation parameters of amygdalin in mixture solvents were analyzed using the inverse Kirkwood–Buff integrals (IKBI) method. Amygdalin is preferentially solvated by water in ethanol-rich mixtures, whereas in water-rich mixtures, there is no clear evidence that determines which of water or ethanol solvents would be most likely to solvate the molecule.
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‘Maltaise demi sanguine’ cultivars are usually grafted on sour orange rootstock. Nonetheless, this rootstock is highly susceptible to Citrus tristeza virus (CTV). A trial was set up in order to ...present new rootstocks as an alternative to sour orange. The effects of eight citrus rootstocks upon the volatile flavor components of the “Maltaise demi sanguine” peel were investigated in both healthy plants and those inoculated with Citrus exocortis viroid (CEVd) and Hop stunt viroid (HSVd). Rootstocks and viroid infection had no significant effect on essential oil yields. Oil components were analyzed by GC-MS. Total of 69 compounds were identified, representing 99% of the total oil. Limonene was the major component in all samples (59.53–95.34%). Principal components and hierarchical cluster analyses revealed that essential oils from plants grafted on Alemow and Carrizo citrange showed the most variable compositions in cases of healthy plants and those inoculated with CEVd. For those plants infected by HSVd, Cleopatra mandarin seemed to be the most affected. Overall, the combined effect of CEVd infection and the use of rootstocks Alemow, Carrizo citrange, and Volkamer lemon had the most pronounced chemical variability.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
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