Key Engineering Materials Vol. 903

Abstract: The study will present results of chemical analysis of mass spectrometry, evaluating the content of pigments in M. domestica leaves dyeing solution and in dyed woollen yarn nowadays. Yarn was dyed with fresh leaves of M. domestica tree. Before dyeing the yarn was treated with potassium aluminium sulphate mordant. Dyestuffs from the yarn were extracted in compliance with modified hydrochloric method of hydrolysis. Extracts were analysed by ultra high-performance liquid chromatography coupled with a diode array detector and mass spectrometry (UHPLC-DAD-MS) for identification of the pigments. Phytochemical screening of dyeing solution of the M. domestica leaves showed presence of dihydrochalcones (phloretin, phlorizin), flavan-3-ols (dimeric B type proanthocyanidin, catechin, epicatechin, gallocatehin, epigallocatechin), flavanols (quercetin derivatives: hyperoside, rutin, quercetrin), phenolic acids and other compounds.

Abstract: Pyrolysis of buckwheat straw with or without catalysts was investigated using the TGA-FTIR method to determine the influence of nickel and cobalt ferrites on the distribution of pyrolysis products. According to the obtained results, the overall shape of the thermogravimetric and derivative thermogravimetric curves is unchanged in the presence of nickel and cobalt ferrites but different weight losses were observed. All catalysts contribute to the formation of solid residue from BWS pyrolysis. The presence of cobalt ferrites exhibited the highest bio-oil yields, whereas the highest non-condensable gas yield and the lowest bio-oil yield was obtained with the addition of NiFe₂O₄ (1) catalyst. According to the obtained results, the ability of nickel and cobalt ferrites to catalyze deoxygenation reactions depends on the crystallite size. The nickel or cobalt ferrites with smaller crystallite size (15-22 nm) show a higher ability to catalyzed dehydration reaction than catalysts with larger crystallite size (45-54 nm).

Abstract: The blends of varying proportions of biodiesel (FAME) containing formate esters of glycerol and 93.0 wt.% fatty acid methyl esters, obtained in an interesterification reaction with methyl formate without further purification, and winter diesel fuel, were prepared, analyzed and compared with winter diesel fuel. The obtained results showed that blends comprising up to 20 vol.% of FAME fulfill the requirements of the standard LVS EN 590 concerning such characteristics as cold flow properties, viscosity, density, and carbon residue. The increase of FAME content worsens the cold flow properties; however, the mixed fuel with 20 vol.% or lower FAME content, according to the cloud point and cold filter plugging point values, remains in the same severe climate "Class 0" group as winter fuel. The carbon residue of mixed fuels raises with increasing FAME content, but stay low and do not exceed the limits of standard for mixtures with FAME percentage up to 20 vol.%. The comparison of mixed fuels containing 20 vol.% of FAME and the same amount of neat biodiesel (99.6 wt.% of fatty acid methyl esters) shows that the difference is negligible. The obtained results have indicated a good potential of FAME obtained in the interesterification reaction with methyl formate without further purification as a diesel fuel additive for up to 20 vol.%.

Abstract: The catalytic hydrotreatment of sunflower (SO), linseed (LO), coconut (CO), rapeseed (RO), and its soapstock derived acid oil (RS) over commercial Ni65%/SiO₂-Al₂O₃ catalyst was investigated to evaluate utilization feasibility of various vegetable oil feedstocks with different fatty acid content, composition, and saturation for marketable hydrocarbon production. The active metal loading of catalyst was characterized by XRF and its textural properties by N₂ sorption analysis. The hydrotreatment tests of different vegetable oils were carried out in solvent free medium, under initial H₂ pressure 10 MPa, at operating temperature 340 oC, and residence time 15 min using catalyst amount 5%. GC-FID and GC-MS analysis were used for estimation of dominant n-pentadecane, n-hexadecane, n-heptadecane, n-octadecane, and other hydrocarbon contents in obtained samples. Under studied hydrotreatment conditions complete conversion of different vegetable oils into marketable liquid renewable hydrocarbons without presence of oxygen containing substances was achieved. Highly active Ni65%/SiO₂-Al₂O₃ has remarkable selectivity to hydrocarbons produced by reaction pathways, where elimination of carbonyl groups occurs. The saturation of fatty acids in feedstock determines H₂ consumption, but influence on produced hydrocarbon production is insignificant. Depending on the fatty acid composition different saturated linear hydrocarbons with wide range of carbon chain length C5-C19 and similar calorific value 47.16-47.34 MJ/kg were produced in process. Overall liquid hydrocarbon yields were from 44.6 % to 78.1 %. The highest overall liquid saturated linear hydrocarbon yield was observed for feedstock with high amount of long chain fatty acids – SO, LO, RO and RS. Pure hydrocarbons obtained from vegetable oils depending on hydrocarbon composition can be used in various areas.

Abstract: Combined coaxial-circular waveguide equipped with protective module allowing the transmission of microwave energy of three magnetrons with the output of 0.9 kW per each into the pressurized reaction chamber and capable of operating at temperatures of up to 250 °C and a pressure of up to 10 bars was designed and tested. Choke flange junction of the waveguide sections was used instead of contact flange connection. The developed waveguide construction allows to place the radio transparent partition inside the free space volume of a choke flange junction performing protection of emitters and summing of microwave energy of three magnetrons with an efficiency close to 100% that was proven by tests with fresh water as a microwave energy absorber. The extraction set-up equipped with the above-mentioned waveguide has demonstrated the stable and safety operation of the transmitting block and the accurate automatic control of the temperature and pressure inside the reaction chamber in the presence of a strong electromagnetic field. The construction of the microwave extraction set-up allows to use the impact of the combination of temperature and pressure on the cell wall, promoting the high rate isolation of secondary metabolites from biomass that was demonstrated by water extraction of black alder bark.

Abstract: The work is devoted to the comprehensive comparative analysis of extraction cakes, obtained after isolation of pharmaceuticals from medical herbs (Aconítum leucostómum, Thermopsis alterniflora, Glycyrrhiza Glabra and Vinca erecta) to characterize their composition and structural features of components, that is necessary for following valorization and for evaluation of extraction efficiency. Application of analytical pyrolysis to analysis of the medical herbs’ residues allowed to avoid disadvantages, connected with preparative isolation of components and get integral information about phytomass constituents and their transformation during extraction. The results have shown that aconite and licorice roots extraction cakes can be considered as perspective raw material for the chemical and biological processing for obtaining of carbohydrates-based products, whereas the periwinkle grass waste is perspective source for obtaining of aromatic and phenolic products. The data of the analytical pyrolysis indicate the сompleteness of biologically active compounds extraction from licorice roots. Extraction cakes of aconite, thermopsis and periwinkle grasses contained different amounts of unextracted targeted pharmaceutical compounds, which can increase their value.

Abstract: Recycled polyethylene terephthalate (r-PET) is a widely recycled plastic employed for new textile production in the world. It reduces environmental impact and lowers cost of the production. For the traditional dyeing of polyethylene terephthalate (PET), commercial disperse dyes are generally used. In presented research the recycled r-PET fibres 6 den dyeing with disperse dyes Itosperse: Red, Blue and Yellow (concentration 3 Wt. %) were examined and the influence of the intensifier of a salicylic acid (with concentration of 4 - 10 g/L) in dye bath was investigated. The colour properties of dyed samples and colour fastness to washing were tested. It is concluded that the presence of the intensifier of salicylic acid improves dyeing results, but the optimal concentration differs for each dye. Colour fastness test to washing of the blue dyed samples showed the insignificant changes of colour parameters. In some cases the change of shade in presence of salicylic acid was observed.

Abstract: The aim of the research was to investigate the pollution level of sulphur and metallic elements in Riga city (Freeport of Riga, Kundziņsala, Mežaparks) by using foliose lichens (Xanthoria parietina) as a bio-indicators. Obtained results show that the Freeport of Riga is the most polluted area comparing with other neatest places in Riga city, Kundziņsala and Mežaparks. Evaluate a washing effect, obtained results shows that lichen thallus contains about 50 % of total amount of sulphur and investigated elements as dust particles on the surface of lichens.

Abstract: A mixed numerical-experimental technique based on vibration tests is modified and applied to determine the elastic material properties of woven composites. This non-destructive technique consists of physical experiments, numerical modelling and material identification procedure. For the purpose of characterization, two carbon fiber panels were prepared by manual layout technology. An evaluation of the accuracy of woven composite elastic properties is executed comparing the numerical and experimentally obtained resonant frequencies.

Abstract: Ethylene-vinyl acetate (EVA) and highly structured carbon black (CB) composites are promising for self-regulating heating materials, especially, were flexibility is needed. Two types of EVA-CB composites were made. Firstly, non-cross-linked EVA-CB composite was made with different CB concentrations and secondly, cross-linked EVA-CB composite with dicumylperoxide (DCP) as the cross-linking agent. Different concentrations of DCP were used. Samples were tested in two ways – by heating them internally (by applying 5V voltage) and externally (by heating in universal heating oven). The electro-thermal properties (including PTC effect) were determined.