microalgae biomass was employed for the extraction of valuable bioactive compounds with deep eutectic-based solvents (DESs). Particularly, the Choline Chloride (ChCl) based DESs, ChCl:1,2 butanediol ...(1:4), ChCl:ethylene glycol (1:2), and ChCl:glycerol (1:2) mixed with water at 70/30
/
ratio were used for that purpose. The extracts' total carotenoid (TCC) and phenolic contents (TPC), as well as their antioxidant activity (IC50), were determined within the process of identification of the most efficient solvent. This screening procedure revealed ChCl:1,2 butanediol (1:4)/H
O 70/30
/
as the most compelling solvent; thus, it was employed thereafter for the extraction process optimization. Three extraction parameters, i.e., solvent-to-biomass ratio, temperature, and time were studied regarding their impact on the extract's TCC, TPC, and IC50. For the experimental design and process optimization, the statistical tool Response Surface Methodology was used. The resulting models' predictive capacity was confirmed experimentally by carrying out two additional extractions under conditions different from the experimental design.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Macroalgae Ulva lactuca, has been employed as a natural source for the production of extracts with potent bioactivity. The biochemical characterization showed that the macroalgae biomass contains a ...remarkable amount of the polysaccharide Ulvan (49.9 wt%) which is a valuable chemical compound well known for its benefits in human health. Four nontoxic solvents, water, ethyl acetate, ethanol, and an ethanol/water mixture (70:30 v/v) were examined for their recovery efficiency of total carotenoid and phenolic contents. Experimental results showed that the aqueous mixture of ethanol was the most efficient solvent in the recovery of bioactive compounds with extraction yield of 10–15% dw. The effect of extraction parameters, namely time, temperature, and the ratio of biomass to solvent, on the carotenoid and phenolic compounds’ content, antioxidant activity, and extraction yield, was investigated, using the ethanol/water mixture as a solvent. The extract obtained under 60 °C, 3 h of extraction time and 1:10 biomass to solvent mass ratio showed the highest antioxidant activity. This extract maintained its antioxidant capacity almost stable for five days of storage under cool and dark conditions. Finally, specific phenolic and carotenoid compounds in the U. lactuca extracts were identified using the High-Performance Liquid Chromatography (HPLC) technique.
Harvesting of microalgae is a crucial step in microalgae-based mass production of different high value-added products. In the present work, magnetic harvesting of Chlorella vulgaris was investigated ...using microwave-synthesized naked magnetite (Fe3O4) particles with an average crystallite diameter of 20 nm. Optimization of the most important parameters of the magnetic harvesting process, namely pH, mass ratio (mr) of magnetite particles to biomass (g/g), and agitation speed (rpm) of the C. vulgaris biomass–Fe3O4 particles mixture, was performed using the response surface methodology (RSM) statistical tool. Harvesting efficiencies higher than 99% were obtained for pH 3.0 and mixing speed greater or equal to 350 rpm. Recovery of magnetic particles via detachment was shown to be feasible and the recovery particles could be reused at least five times with high harvesting efficiency. Consequently, the described harvesting approach of C. vulgaris cells leads to an efficient, simple, and quick process, that does not impair the quality of the harvested biomass.
•Solubility measurements for three cinnamic acid derivatives in Deep Eutectic Solvents.•Density and viscosity measurements of ChCl:1,2 butanediol (1:4) and ChCl:1,4 butanediol (1:4).•ChCl:1,4 ...butanediol (1:4) and ChCl:1,2 butanediol (1:4) exhibit the highest solvation capacity.•Dissolution process is endothermic and not spontaneous for all systems studied.•UNIQUAC and NRTL activity coefficient models successfully correlate the experimental solubility data.
This work presents experimental solubility measurements for three cinnamic acid derivatives (CADs) namely caffeic acid (CA), p-coumaric acid (p-CA) and ferulic acid (FA) in three Deep Eutectic Solvents (DESs), choline chloride-1,2 butanediol (ChCl:1,2 butanediol (1:4)), choline chloride-1,4 butanediol (ChCl:1,4 butanediol (1:4)) and choline chloride-acetic acid (ChCl:Acetic Acid (1:2)). All measurements were performed in the temperature range of 293.15 to 323.15 K and at atmospheric pressure. Density and viscosity measurements of pure DESs ChCl:1,2 butanediol (1:4) and ChCl:1,4 butanediol (1:4) are also reported. ChCl:1,4 butanediol (1:4) and ChCl:1,2 butanediol (1:4) reveals the highest solvation capacity for CADs among the examined solvents, while p-CA was found to be less soluble than CA and FA in all solvents. Thermodynamic functions of dissolution were also determined using the Van’t Hoff equation and the results imply that the process is endothermic for all systems studied. Finally, UNIQUAC and NRTL activity coefficient models were satisfactorily implemented to correlate the experimental solubilities.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Efficient and reliable energy storage systems are necessary to address the intermittency and variability of renewable energy sources. Thermochemical energy storage (TCES) has emerged as a promising ...solution for long-term renewable energy storage, with limestone being a widely studied material due to its abundance and high energy density. However, the practical implementation of limestone-based TCES systems faces challenges related to performance degradation upon multiple energy storage/release cycles, impacting their long-term viability and efficiency. In this study, we investigate the activity of Ca 2 Fe 2 O 5 additives on the thermochemical energy storage performance of limestone waste. Ca 2 Fe 2 O 5 additives were synthesized by a wet precipitation method using three different Ca/Fe molar ratios and added to limestone waste in a 5, 10, and 20 weight concentration. The synthesized samples were characterized using XRD, SEM, EDS, BET, and XPS techniques. The thermal properties and heat storage performance of the samples were evaluated through thermogravimetric analysis of calcination/carbonation cycling experiments. The results demonstrate the potential of Ca 2 Fe 2 O 5 additives to improve the cycling stability and energy storage density of limestone-based TCES systems. The sample with 5 wt% of Ca 2 Fe 2 O 5 additive having Ca : Fe molar ratio of 1 : 1 outperformed all samples with an effective conversion rate of 0.21 after 40 cycles, 1.31 times higher than limestone waste.
Full text
Available for:
IJS, KILJ, NUK, UL, UM, UPUK
C. vulgaris microalgae biomass was employed for the extraction of valuable bioactive compounds with deep eutectic-based solvents (DESs). Particularly, the Choline Chloride (ChCl) based DESs, ChCl:1,2 ...butanediol (1:4), ChCl:ethylene glycol (1:2), and ChCl:glycerol (1:2) mixed with water at 70/30 w/w ratio were used for that purpose. The extracts’ total carotenoid (TCC) and phenolic contents (TPC), as well as their antioxidant activity (IC50), were determined within the process of identification of the most efficient solvent. This screening procedure revealed ChCl:1,2 butanediol (1:4)/Hsub.2O 70/30 w/w as the most compelling solvent; thus, it was employed thereafter for the extraction process optimization. Three extraction parameters, i.e., solvent-to-biomass ratio, temperature, and time were studied regarding their impact on the extract’s TCC, TPC, and IC50. For the experimental design and process optimization, the statistical tool Response Surface Methodology was used. The resulting models’ predictive capacity was confirmed experimentally by carrying out two additional extractions under conditions different from the experimental design.
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Efficient and reliable energy storage systems are necessary to address the intermittency and variability of renewable energy sources. Thermochemical energy storage (TCES) has emerged as a promising ...solution for long-term renewable energy storage, with limestone being a widely studied material due to its abundance and high energy density. However, the practical implementation of limestone-based TCES systems faces challenges related to performance degradation upon multiple energy storage/release cycles, impacting their long-term viability and efficiency. In this study, we investigate the activity of Ca2Fe2O5 additives on the thermochemical energy storage performance of limestone waste. Ca2Fe2O5 additives were synthesized by a wet precipitation method using three different Ca/Fe molar ratios and added to limestone waste in a 5, 10, and 20 weight concentration. The synthesized samples were characterized using XRD, SEM, EDS, BET, and XPS techniques. The thermal properties and heat storage performance of the samples were evaluated through thermogravimetric analysis of calcination/carbonation cycling experiments. The results demonstrate the potential of Ca2Fe2O5 additives to improve the cycling stability and energy storage density of limestone-based TCES systems. The sample with 5 wt% of Ca2Fe2O5 additive having Ca : Fe molar ratio of 1 : 1 outperformed all samples with an effective conversion rate of 0.21 after 40 cycles, 1.31 times higher than limestone waste.
Full text
Available for:
IJS, KILJ, NUK, UL, UM, UPUK
Efficient and reliable energy storage systems are necessary to address the intermittency and variability of renewable energy sources. Thermochemical energy storage (TCES) has emerged as a promising ...solution for long-term renewable energy storage, with limestone being a widely studied material due to its abundance and high energy density. However, the practical implementation of limestone-based TCES systems faces challenges related to performance degradation upon multiple energy storage/release cycles, impacting their long-term viability and efficiency. In this study, we investigate the activity of Ca
2
Fe
2
O
5
additives on the thermochemical energy storage performance of limestone waste. Ca
2
Fe
2
O
5
additives were synthesized by a wet precipitation method using three different Ca/Fe molar ratios and added to limestone waste in a 5, 10, and 20 weight concentration. The synthesized samples were characterized using XRD, SEM, EDS, BET, and XPS techniques. The thermal properties and heat storage performance of the samples were evaluated through thermogravimetric analysis of calcination/carbonation cycling experiments. The results demonstrate the potential of Ca
2
Fe
2
O
5
additives to improve the cycling stability and energy storage density of limestone-based TCES systems. The sample with 5 wt% of Ca
2
Fe
2
O
5
additive having Ca : Fe molar ratio of 1 : 1 outperformed all samples with an effective conversion rate of 0.21 after 40 cycles, 1.31 times higher than limestone waste.
Activation energy for CaCO
3
calcination reaction was reduced using Ca
2
Fe
2
O
5
additives which improved the thermochemical cycling capacity of limestone waste.
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IJS, KILJ, NUK, UL, UM, UPUK
Coumarins has served as the prototype scaffold for the synthesis of a wide variety of analogues in order to investigate their biological activity as well as their use as additives (levelers or/and ...brightners) in metal electroplating industrial processes. Several synthetic coumarin derivatives have important pharmacological potential as they proved to be efficient inhibitors of a variety of enzymes. Moreover, coumarin and its derivatives, might also present interesting physical and chemical properties that, in many cases, could be attributed to the development of a p-conjugated system in their molecules. In the present work, a series of coumarin analogues, bearing a substituted phenyl ring on position 3, synthesized via a novel methodology, have been studied as far as concerns their photoconductivity. Specifically, the effect of the nature, the number and the position of substituents, have been investigated. The structure of the molecules was studied by X-ray crystallography. The photoelectrical behavior of the substances was detected using a photoelectrochemical cell (PEC) under a white illumination generated by a halogen lamp and focused in front of the quartz window of the cell. Illumination intensity was approx. 1,000 and 10,000 W/m2. It was found that a relation exists between the photoresistivity of the compounds, their molecular structure andthe orientation of their crystallites in thin films prepared from them.
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