Choline chloride-based deep eutectic solvents in CaO-catalyzed ethanolysis of expired sunflower oil

Choline chloride (ChCl)-based deep eutectic solvents (DESs) with different amides or polyols as hydrogen bond donors were tested as cosolvents in the ethanolysis of expired sunflower oil catalyzed by either calcined or non-calcined CaO. These cosolvents promoted the ethanolysis by a successful activation of non-calcined CaO, which was ascribed to the CaCO3 and Ca(OH)2 dissolution from the surface of the solid catalyst particles. With both calcined and non-calcined CaO, the polyol-based solvents gave higher fatty acid ethyl esters (FAEE) content than the amide-based solvents. Among the amide-based DESs, choline chloride:urea (ChCl:U) was the most efficient activator of non-calcined CaO. Choline chloride:ethylene glycol (ChCl:EG) and choline chloride:propylene glycol (ChCl:PG) were more efficient than choline chloride:glycerol (ChCl:G) even with non-calcined CaO. However, ChCl:G might be more suitable than the others since the use of glycerol, a by-product of the ethanolysis, could reduce the overall biodiesel production costs. FTIR and XRD analyses of the used and separated CaO were performed in order to get more insight into the catalytically active phase(s). Also, the mechanisms of the CaO activation in the presence of the DESs were considered. The phase separation of the reaction mixture was faster in the presence of the DESs. Since ChCl:U and ChCl:G DESs are nontoxic, biodegradable, biorenewable and “green” solvents and provide the elimination of the calcination step of CaO, thus reducing the overall process costs, the non-calcined CaO catalytic systems with these DESs are recommended for further optimization. © 2018 Elsevier B.V.Published version: [https://hdl.handle.net/21.15107/rcub_dais_3694]This is the peer reviewed version of the following article: Troter, D.Z., Todorović, Z.B., Đokić-Stojanović, D.R., Veselinović, L.M., Zdujić, M.V., Veljković, V.B., 2018. Choline chloride-based deep eutectic solvents in CaO-catalyzed ethanolysis of expired sunflower oil. Journal of Molecular Liquids 266, 557–567. [https://doi.org/10.1016/j.molliq.2018.06.106]Supplementary information: [https://hdl.handle.net/21.15107/rcub_dais_3772

Citric Acid Cross-Linked Gelatin-Based Composites with Improved Microhardness

The aim of this study is to investigate the influence of cross-linking and reinforcements in gelatin on the physico-mechanical properties of obtained composites. The gelatin-based composites cross-linked with citric acid (CA) were prepared: gelatin type B (GB) and β-tricalcium phosphate (β-TCP) and novel hybrid composite GB with β-TCP and hydroxyapatite (HAp) particles, and their structure, thermal, and mechanical properties were compared with pure gelatin B samples. FTIR analysis revealed that no chemical interaction between the reinforcements and gelatin matrix was established during the processing of hybrid composites by the solution casting method, proving the particles had no influence on GB cross-linking. The morphological investigation of hybrid composites revealed that cross-linking with CA improved the dispersion of particles, which further led to an increase in mechanical performance. The microindentation test showed that the hardness value was increased by up to 449%, which shows the high potential of β-TCP and HAp particle reinforcement combined with CA as a cross-linking agent. Furthermore, the reduced modulus of elasticity was increased by up to 288%. Results of the MTT assay on L929 cells have revealed that the hybrid composite GB-TCP-HA-CA was not cytotoxic. These results showed that GB cross-linked with CA and reinforced with different calcium phosphates presents a valuable novel material with potential applications in dentistry

Citric Acid Cross-Linked Gelatin-Based Composites with Improved Microhardness

The aim of this study is to investigate the influence of cross-linking and reinforcements in gelatin on the physico-mechanical properties of obtained composites. The gelatin-based composites cross-linked with citric acid (CA) were prepared: gelatin type B (GB) and β-tricalcium phosphate (β-TCP) and novel hybrid composite GB with β-TCP and hydroxyapatite (HAp) particles, and their structure, thermal, and mechanical properties were compared with pure gelatin B samples. FTIR analysis revealed that no chemical interaction between the reinforcements and gelatin matrix was established during the processing of hybrid composites by the solution casting method, proving the particles had no influence on GB cross-linking. The morphological investigation of hybrid composites revealed that cross-linking with CA improved the dispersion of particles, which further led to an increase in mechanical performance. The microindentation test showed that the hardness value was increased by up to 449%, which shows the high potential of β-TCP and HAp particle reinforcement combined with CA as a cross-linking agent. Furthermore, the reduced modulus of elasticity was increased by up to 288%. Results of the MTT assay on L929 cells have revealed that the hybrid composite GB-TCP-HA-CA was not cytotoxic. These results showed that GB cross-linked with CA and reinforced with different calcium phosphates presents a valuable novel material with potential applications in dentistry

Supplementary data for article: Đokić-Stojanović, D. R.; Todorović, Z. B.; Troter, D. Z.; Stamenković, O. S.; Veselinović, L. M.; Zdujić, M. V.; Manojlović, D. D.; Veljković, V. B. Triethanolamine as an Efficient Cosolvent for Biodiesel Production by Cao-Catalyzed Sunflower Oil Ethanolysis: An Optimization Study. Hemijska Industrija 2019, 73 (6), 351–362. https://doi.org/10.2298/HEMIND190822033D

Supplementary material for: [https://doi.org/10.2298/HEMIND190822033D]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/3797

Triethanolamine as an efficient cosolvent for biodiesel production by cao-catalyzed sunflower oil ethanolysis: An optimization study

Triethanolamine was applied as an efficient „green“ cosolvent for biodiesel production by CaO-catalyzed ethanolysis of sunflower oil. The reaction was conducted in a batch stirred reactor and optimized with respect to the reaction temperature (61.6-78.4 °C), the ethanol-to-oil molar ratio (7:1-17:1) and the cosolvent loading (3-36 % of the oil weight) by using a rotatable central composite design (RCCD) combined with the response surface methodology (RSM). The optimal reaction conditions were found to be: the ethanol-to-oil molar ratio of 9:1, the reaction temperature of 75 °C and the cosolvent loading of 30 % to oil weight, which resulted in the predicted and actual fatty acid ethyl ester (FAEE) contents of 98.8 % and 97.9±1.3 %, respectively, achieved within only 20 min of the reaction. Also, high FAEE contents were obtained with expired sunflower oil, hempseed oil and waste lard. X-ray diffraction analysis (XRD) was used to understand the changes in the CaO phase. The CaO catalyst can be used without any treatment in two consecutive cycles. Due to the calcium leaching into the product, an additional purification stage must be included in the overall process.Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3798

Supplementary data for article: Đokić-Stojanović, D. R.; Todorović, Z. B.; Troter, D. Z.; Stamenković, O. S.; Veselinović, L. M.; Zdujić, M. V.; Manojlović, D. D.; Veljković, V. B. Triethanolamine as an Efficient Cosolvent for Biodiesel Production by Cao-Catalyzed Sunflower Oil Ethanolysis: An Optimization Study. Hemijska Industrija 2019, 73 (6), 351–362. https://doi.org/10.2298/HEMIND190822033D

Supplementary material for: [https://doi.org/10.2298/HEMIND190822033D]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/3797

Analiza formiranja PVB-SiO2 nanokompozitnih vlakana pomoću elektrospining procesa

The poly (vinyl butyral)-silica (PVB-SiO2) nanofibers were obtained by the electrospinning process. The experiments were carried out with PVB solution in concentration of 10 wt.% where ethanol was used as the solvent. The silica nanoparticles were added in the solution in different contents of 1, 3 and 5 wt.% SiO2 and nanoparticles were modified with γ-aminopropyltriethoxysilane (AMEO silane). The impacts of the parameters of the electrospinning process and the silica nanoparticles on the produced PVB-SiO2 nanocomposite fibers were tested. The structures of the PVB-SiO2 nanocomposite fibers were investigated using optical microscopy and scanning electron microscopy (SEM). The morphology and distribution of the resulting nanofibers were analyzed using the software Image-Pro Plus. .Poli (vinil butiral)-silika (PVB-SiO2) nanovlakna su dobijena metodom elektrospininga. Eksperimenti su izvedeni u rastvoru 10 mas.% PVB-a u etanolu koji je korišćen kao rastvarač. Nanočestice silike su dodate sa različitim sadržajem od 1, 3 i 5 mas.% SiO2 i modifikovane γ-aminopropiltrietoksi silanom (AMEO silanom). Istražen je uticaj procesnih parametara elektrospininga na nanokompozitna vlakna PVB-SiO2. Struktura PVB-SiO2 nanokompozitnih vlakana je proučavana pomoću optičke mikroskopije i skenirajuće elektronske mikroskopije (SEM). Morfologija proizvedenih nanokompozitnih vlakana i njihova raspodela je analizirana u Image Pro Plus softveru.

Fractal analysis and microstructure development of BaTiO3 and PVDF based multifunctional materials

Barium titanate (BaTiO3) and polyvinylidene fluoride (PVDF) based multifunctional materials are attracting a great scientific interest due to their excellent piezoelectric, pyroelectric and ferroelectric properties. These materials undergo controlled transformations through physical interactions and respond to environmental stimuli, such as temperature, pressure, electric and magnetic fields. Their properties strongly depend on synthesis procedures and obtained microstructures. This include intergranular contact surfaces of BaTiO3 based materials, as well as, porous structure and cross-linking patterns of PVDF prepared by electrospinning. It has been found that these microstructures can have fractal structure and that the fractal analysis can be used as a powerful tool for describing structural and functional properties of these materials. Having this in mind, in this research we have used different fractal methods for the reconstructions of various BaTiO3 and PVDF microstructure morphologies. Fractal analysis has been performed by using scanning electron microscope micrographs and computational modeling tools. Fractal dimension of irregular morphologies which exhibit fractal regularity were determined by using box-counting method. This method enables the analysis of self-similar microstructure morphologies by quantifying the rate at which an object's geometrical details develop at increasingly fine scales. Theory of Iterated Function Systems and Voronoi tessellation, have been used for modeling BaTiO3 random microstructures and PVDF porous structures. A python algorithm was created to determine the distribution of pore areas in SEM micrographs. Algorithm’s distribution of calculated pore surface areas was compared with measured pore surface areas and fractal reconstructions of different morphologies and their connection with functional properties were analyzed

Heterogeno katalizovana etanoliza suncokretovog ulja u prisustvu polietilen glikola, etil acetata i dietil etra kao kosolvenata

A heterogeneous reaction process using propylene glycol (PEG), ethyl acetate and diethyl ether as cosolvents for the transesterification of sunflower oil with ethanol in the presence of calcium oxide as a catalyst has been developed. Significant results were obtained with propylene glycol as a cosolvent. Under determined reaction conditions (CaO concentration, based on the oil weight 1.3736 mol∙dm-3; temperature 70°C; and ethanol-to-oil molar ratio 12:1), the conversion of sunflower oil to fatty acid ethyl esters (FAEE) exceeded 98% after 120 min, which was 2 times faster than transesterification of sunflower oil without a cosolvent. After initially enhanced ethanolysis, after 180 min ethyl acetate and diethyl ether negatively influenced the reaction rate and the FAEE yield.U radu je opisana heterogena transesterifikacija suncokretovog ulja sa etanolom i kalcijum oksidom kao katalizatorom u prisustvu polietilen glikola (PEG), etil acetata i dietil etra kao kosolvenata. Najpovoljniji rezultati su dobijeni sa polietilen glikolom kao kosolventom gde je, pod određenim reakcionim uslovima (koncentracija CaO, računata u odnosu na masu ulja 1.3736 mol∙dm-3, temperatura 70°C i molarni odnos etanol:ulje 12:1), konverzija suncokretovog ulja u etil estre masnih kiselina (FAEE) dostigla vrednost od 98% nakon 120 minuta, što je 2 puta brže od transesterifikacije suncokretovog ulja bez prisustva kosolventa. Etil acetat i dietil etar poboljšavaju reakciju etanolize na početku, ali, kako reakcija napreduje, posle 180 minuta, njihovo prisustvo u reakcionoj smeši negativno utiče na brzinu reakcije i prinos etil estrara masnih kiselina (FAEE)

The physicochemical and thermodynamic properties of the choline chloride-based deep eutectic solvents

This paper reports the physicochemical (density, dynamic viscosity, electrical conductivity and refractive index) and the thermodynamic (thermal expansion coefficient, molecular volume, lattice energy and heat capacity) properties of several choline chloride (ChCl) based deep eutectic solvents (DESs), with 1:2 mole ratio, respectively:ChCl:propylene glycol, ChCl:1,3-dimethyl-urea and ChCl:thiourea, at atmospheric pressure as a function of temperature over the range of 293.15-363.15 K. Their properties were also compared with those of some already characterized ChCl-based DESs, namely ChCl:ethylene glycol, ChCl:glycerol and ChCl:urea (1:2 mole ratio). Density, viscosity and refractive index of all DESs decrease with the increasing temperature while the electrical conductivity increases. Viscosity and conductivity of the tested DESs were fitted by both Arrhenius-type and Vogel-Tamman-Fulcher equations. The changes of molar enthalpy, entropy and Gibbs energy of activation, determined using the Eyring theory, demonstrated the interactional factor as predominant over the structural factor for all DES systems. The fractional Walden rule, used to correlate molar conductivity and viscosity, showed an excellent linear behaviour. It was shown that ChCl:propylene glycol DES had properties similar to ChCl:ethylene glycol and ChCl:glycerol DESs. However, the properties (density, viscosity and electrical conductivity) of ChCl:1,3-dimethylurea and ChCl::thiourea DESs were inferior to those of the ChCl:urea DES