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Informuojame, kad nuo 2012 m. žurnalo „Cheminė technologija“ antrojo numerio keičiasi redakcinės kolegijos sudėtis, taip pat keičiasi nurodymai straipsnių autoriams. Todėl prašome straipsnių autorių ateityje rankraščius redakcinei kolegijai teikti jau pagal naujuosius reikalavimus. Straipsnių parengimo reikalavimai yra pateikti leidinyje ir interneto svetainėje adresu: http://www.chemtech.ktu.lt Kauno technologijos universiteto mokslo periodiniame leidinyje „Cheminė technologija“ publikuojami originalūs, kitur neskelbti organinių ir neorganinių medžiagų technologijos, maisto chemijos ir technologijos, biotechnologijos, farmakologijos technologijų moksliniai straipsniai ir apžvalgos lietuvių arba anglų kalbomis. Žurnalo redakcinės kolegijos nariai skatina originalių straipsnių, kuriuose aprašyti cheminės technologijos ir kitų giminingų mokslo krypčių (chemijos ir biochemijos, medžiagotyros ir aplinkosaugos inžinerijos) integruotų tyrimų rezultatai, publikavimą. Žurnale gali būti publikuojami metodologiniai, apžvalginiai, kritiniai, informaciniai (apie jubiliejus, konferencijas, mokslinį bendradar-biavimą, mokslo ir studijų institucijas) straipsniai. Kviečiame mokslininkus rašyti mokslinius straipsnius į šį leidinį ir dalytis savo moksline patirtimi.
ANTIOXIDANT ACTIVITY IN NETTLE (URTICA DIOICA L.) AND GARDEN ORACHE (ATRIPLEX HORTENSIS L.) LEAVES DURING VEGETATION PERIOD
Different vegetables are a good source of essential components for human food. Consumers are more and more aware of a healthy and balanced diet. Vegetables usually contain natural antioxidants which neutralize free radicals in the human body. The composition of biologically active compounds in plants is depending on the climate and growing conditions, cultivar properties, plant development stage, harvesting time, and other factors. The aim of the research was to evaluate the fluctuation of antioxidant activity in leaves of four common nettle (Urtica dioca L.) clones and three garden orache (Atriplex hortensis L.) varieties during vegetation period in Latvian conditions. Experiments were carried out in open field conditions in the Pūre Horticultural Research Centre during the vegetation period of 2014, in two soil fertility variants for nettle and two sowing periods for garden orache. Antiradical activity was determined using the 2.2-diphenyl-1-picrylhydrazyl radical (DPPH*) method. In nettle leaves, antioxidant activity ranged between 17.31–80.77 %, depending on soil fertility, nettle clone and plant age, and in orache leaves between 17.9–54.0 % depending on variety and sowing time. In nettle leaves, the antioxidant activity at the beginning of the vegetation period ranged between 31.0–62.7 %, the highest activity was observed at the stem elongation stage (75.5–78.5 %). A higher antiradical activity was detected in the control variant (without compost treatment) at the 3–5 and 7–9 leaves stage. In other development stages, better results were obtained in the fertilized variant where compost and peat were used as an organic manure. Differences were found also among clones, especially in the 3–5 leave stage. Significant differences for garden orache leaves were found between sowing times. In the first growing period the antiradical activity ranged between 46.1–54.0 %, in the second it was two times less. DOI: http://dx.doi.org/10.5755/j01.ct.66.1.12055
CHEMICAL COMPOSITION OF TOMATOES DEPENDING ON THE STAGE OF RIPENING
Tomatoes are well-known vegetables, grown and eaten around the world due to their nutritional benefits. The aim of this research was to determine the chemical composition (dry matter, soluble solids, titritable acidity, vitamin C, lycopene), the taste index and maturity in three cherry tomato varieties (Sakura, Sunstream, Mathew) grown and collected from greenhouse at different stages of ripening. The output of the analyses showed that there were significant differences in the mean values among the analysed parameters according to the stage of ripening and variety. During ripening, the content of soluble solids increases on average two times in all analyzed varieties; the highest content of vitamin C and lycopene was determined in tomatoes of Sunstream variety in red stage. The highest total acidity expressed as g of citric acid 100 g-1 was observed in pink stage (variety Sakura) or a breaker stage (varieties Sunstream and Mathew). The taste index of the variety Sakura was higher at all analyzed ripening stages in comparison with other varieties. This shows that ripening stages have a significant effect on tomato biochemical composition along with their variety. DOI: http://dx.doi.org/10.5755/j01.ct.66.1.12053
TECHNOLOGICAL PROPERTIES OF DOUGH FROM WHEAT FLOUR AND FERMENTED BRAN
Protein quality and quantity are related with dough properties and loaf form. However, an important factor for dough quality is the composition of flour mix. Nowadays, scientists develop new products with the increasing nutritive value, using oatmeal, buckwheat flour, bran. Wheat bran is a composite material formed from different histological layers, and three different strips can be obtained from the soaked outer layers. The investigations suggest that enzymatic treatments of wheat bran are effective methods to improve the concentration of bioactive compounds, antioxidant activity and water-soluble dietary fibre. The aim of the study is to estimate the technological properties of wheat dough with bran and fermented bran. Wheat flour was substituted with bran and fermented bran (5, 7, 10, 15 %). The following quality parameters were analysed using standard methods: the rheological properties of dough were analysed using Brabender Farinograph-AT (GmbH&Co.KG., Germany), and the moisture content of flour samples was determined according to the AACC 44-15A (2000). The results of the present research demonstrate that the rheological properties of dough decrease is wheat flour substituted with 15 % of fermented bran. Water absorption and dough development time of dough with fermented bran addition is less than the parameters of control wheat flour. DOI: http://dx.doi.org/10.5755/j01.ct.66.1.12360
SENSORY ASPECTS AND CONSUMER ACCEPTANCE OF CERTAIN LEGUME EXTRUDED SNACKS
Legumes are an important source of protein for the human diet. Still they are underutilized mainly because they have a long preparation time, even when the protein content is higher than in grains. In order to make legumes more utilized, snacks from different legume flours were made using a twin screw extrusion cooker. In this paper, extruded snacks made of three different legume bases from grey pea (Pisum sativum L.), cow pea (Vigna unguiculata (L.) Walp) and faba bean (Vicia faba L.) were analysed. The obtained products were divided and spice coated, and control samples without coating were made. A questionnaire was carried out in order to ascertain consumers' opinion about extruded snacks. In order to determine which snacks would be most likable, sensory analyses were carried out. Consumers from different European countries were asked to determine likeness using a 5-point hedonic scale. Best results were obtained for sweet snacks with almond taste, based of grey pea (Pisum sativum L.) and salty snacks with onion taste, both of grey pea (Pisum sativum L.) extrudates and cow pea (Vigna unguiculata (L.) Walp.) extrudates. Unfortunately, participants didn’t have a consensus about the quantity of spiciness. Such differences can be explained by different tastes. DOI: http://dx.doi.org/10.5755/j01.ct.66.1.12362
INVESTIGATION OF PHYSICOCHEMICAL, SENSORY CHARACTERISTICS, COOKING AND TEXTURE PROPERTIES OF WHOLE GRAIN PASTA
The consumption of whole-grain products, such as pasta, has been linked to the reduced risks of some illnesses. Nutritional benefits include dietary fibre, minerals, and phytochemicals. Traditionally, whole-grain products tend to be darker in colour, fiber can interfere with the drying process affecting production processes. The purpose of the current research was to investigate the colour, cooking properties and texture of the whole-grain pasta. For pasta production, flour blends were made from wheat flour type 405 in combination with whole-grain flours as whole-grain wheat, triticale, rye and hull-less barley flour in previously determined proportions. In experiments, the whole-grain Italpasta (Italy) was used as a control sample. The colour, cooking properties and texture of the obtained pasta were tested using standard methods. The results of the present experiments demonstrate that the cooking time of control, whole-grain triticale and wheat pasta was longer than the cooking time of whole-grain rye and hull-less barley pasta. The colour of control, whole-triticale and whole-wheat pasta samples was darker as compared with whole-rye and hull-less barley pasta samples. However, more firmness had pasta samples made from whole-rye and hull-less barley whole-grain flour. DOI: http://dx.doi.org/10.5755/j01.ct.66.1.12364
The influence of 3-(1H-Benzimidazol-2-yl)-4-phenylaminobutanoic acid sodium salt on summer rapeseed (Brassica napus L.) yield and oil quality
The influence of the biological activity of various concentrations of 3-(1H-benzimidazol-2-yl)-4-phenylaminobutanoic sodium salt on summer rapeseed was studied by the laboratory screening in vitro and in field conditions. It was determined that the study compound stimulated rapeseed growth, increased their yield and had a positive effect on the oil quality. This compound increased plant biomass in vitro and root length by 2 mg/l. In the field trials, rapeseed seedlings were sprayed with a 100 mg/l solution, and the number of siliques and the weight of seeds were found to be increased. When seedlings were sprayed with 125 mg/l solution of the compound, the content of oil increased. The content of flavonoids and the radical scavenging activity were highest when seedlings were sprayed with a 75 mg/l solution of the compound. DOI: http://dx.doi.org/10.5755/j01.ct.63.1.4514
EVALUATION OF SECONDARY METABOLITES’ VARIATION IN MEDICINAL PLANTS AND OPTIMIZATION OF SAGE (SALVIA OFFICINALIS L.) GROWTH IN VITRO
Plants produce a wide variety of secondary metabolites that have been selected during evolution as defense substances against herbivores, predators or infective microbes and viruses, or as signal compounds. These secondary compounds have attracted great interest for drug development as they may represent lead structures for new or already existing drug targets. The goals of the research: 1) to explore metabolites (total phenolic compounds, flavonoids, vitamin C) and the antioxidant activity of medicinal plants in vivo; 2) to select medicinal plants which have accumulated the highest content of secondary metabolites; 3) to prepare the culture media with different pH values for the sage in vitro; 4) to prepare the culture media with different KH2PO4 quantities for the sage (Salvia officinalis L.) in vitro; 5) to explore secondary metabolites (total phenolic compounds, vitamin C, tannins) of the sage in vitro; 6) to compare the content of metabolites of sage plants in vivo and in vitro; In conclusion, in order to grow sage (Salvia officinalis L.) which would give a large biomass and produce large quantities of metabolites, it is useful to increase the amount of KH2PO4 two times in the Murashige–Skoog (MS) nutrient medium and to maintain pH within 5.7–6.7. Sage (Salvia officinalis L.) was found to accumulate the larger amount of metabolites in vitro, i.e. 1.7 times of tannins, 3.8 times of the vitamin C, and 3 times of flavonoids in comparison with the sage in vivo. DOI: http://dx.doi.org/10.5755/j01.ct.64.2.6021
COMPOUND FORMATION AT 175 °C IN CALCIUM HYDROXIDE AND SILICA DIOXIDE SUSPENSION
Compound formation peculiarities in the Ca(OH)2–SiO2∙nH2O–H2O system with the molar ratio of CaO/SiO2 equal to 1.5 have been examined. The hydrothermal synthesis of the compounds has been carried out in unmixed suspensions at a temperature of 175 °C. The duration of isothermal curing was 4, 8, 16, 24, 48, and 72 hours. In unstirred Ca(OH)2 and SiO2∙nH2O suspensions with CaO/SiO2 = 1.5, within 4 hours of isothermal curing at 175 °C, dicalcium silicate hydrates – a-C2S hydrate, C-S-H(II) and a low base semi-crystalline C-S-H(I) type calcium silicate hydrate – were formed. Within 48 h of hydrothermal synthesis, Ca(OH)2 was fully reacted, and semi-crystalline C-S-H(II) became metastable and recrystallized into stable compounds – a-C2S hydrate and C-S-H(I). The typical destruction temperatures of a-C2S hydrate and Ca(OH)2 were possible to determine by using differential thermogravimetric analysis data: the destruction of Ca(OH)2 intensively proceeded at a temperature of ~456 ºC when a sample lost 1.85 % of its mass. Meanwhile, a-C2S hydrate destruction occurred at a higher temperature (~478 ºC), and weight loss was equal to 0.58 %. After 72 h of synthesis, a-C2S hydrate prevailed in the products. DOI: http://dx.doi.org/10.5755/j01.ct.64.2.6100
INFLUENCE OF POTASSIUM RAW MATERIALS ON THE BULK FERTILIZER MAKING PROCESS AND ON THE PRODUCT PROPERTIES
In this work, different sources of potassium materials were used for 10-20-20 + S + Mg fertilizer granulation. It was found that both the raw material KCl and magnesium from carnallite production by-products (KE) can be used for fertilizer making. With both potassium raw materials, upon selecting certain granulation process parameters, it is possible to make a high-quality product. To produce a high quality 10-20-20 + S + Mg NPK fertilizer which would be a marketable fraction, using KE requires less moisture than granulation using KCl. If the water content with KCl is 10.1 %, with a sufficient KE it is 8.8 %. However, the drying of fertilizers requires higher energy costs, as maintaining the same drying temperature and the same drying time, the fertilizer produced with KE, the remaining moisture content is 1–3 %, and this is a too high moisture for a fertilizer. The marketable fraction produced using KE is less dependent on raw material mixture granulometric composition than with KCl. The origin potassium raw materials has no significant influence on the static strength of granules. DOI: http://dx.doi.org/10.5755/j01.ct.64.2.6099
PRODUCING CALCIUM NITRATE AND RARE-EARTH ELEMENT CONCENTRATES BY PHOSPHOGYPSUM CONVERSION
Experimental researches of the dissolution of calcium carbonate obtained as a result of phosphogypsum conversion by ammonium or sodium carbonate and nitric acid with obtaining a concentrate of rare-earth elements and other liquid products have been performed. The structure of phosphochalk and the outlet half-product is presented. The substantiation of recycling expediency of phosphogypsum waste – phosphoric acid and phosphoric fertilizers has been carried out. DOI: http://dx.doi.org/10.5755/j01.ct.64.2.6024
Evaluation of pumpkin-rowanberry marmalade quality after different drying times
Historically, marmalades may have originated as an early effort to preserve fruit for consumption in the off-season. Marmalades are basically products with fruit purée and sugar–acid–pectin gel. The aim of the current research was to determine the chemical and physical properties and to investigate the degree of acceptance of pumpkin–rowanberry marmalade. The experiments were carried out at the Faculty of Food Technology of the Latvia University of Agriculture. The marmalade was made from Cucurbita maxima pumpkin and sweet rowanberry Sorbus aucuparia cultivar ‘Nevezhinskaya’ purées. Different drying times in oven at a temperature of 50 ± 2 °C were examined and compared with marmalade drying in air ambiance at room temperature. The moisture, total carotene, ascorbic acid content, hardness, colour, and the degree of acceptance of marmalade samples were determined as quality evaluation. The results of the research have shown a large variability in the physical and chemical parameters among the marmalades after different drying times. The moisture content of marmalade samples decreased by 9.1 to 33.5 %, and hardness increased from 1.85 to 9.54 N. According to sensory evaluation, consumers liked pumpkin–rowanberry marmalade samples after drying in the air ambiance at room temperature. DOI: http://dx.doi.org/10.5755/j01.ct.62.4.3412
The influence of different copper concentrations on barley grain sprouting and the content of total phenols
Barley is a major world crop ranked as the fourth most important cereal in terms of plant area. Barley is consumed around the world, mostly in the malted form in brewing industry. Recently, many investigations in malt production intensification with biologically active compounds or ferment preparations have been accomplished. However, comprehensive studies on the effect of copper additives on barley grain sprouting are still required. The aim of this study was to explore the influence of different copper concentrations on barley grain sprouting and on the content of total phenols. Barley grains of 92 % viability were soaked in different solutions (Cu2+ concentration 10–500 mg/l) for 12 hours, left for sprouting at a temperature of 18 ± 2 °C for 5 days, and then dried in the oven for 48 hours at 50 °C. The control sample of grain was soaked in deionized water. The sprouting activity of the grain was determined after sprouting, whereas the content of total phenols was determined after the grain had dried out. The obtained results show that at the copper concentration of 10–50 mg/l, barley grain sprouting activity increases essentially. At the copper concentration of 100 mg/l, barley grain sprouting decreases sharply; moreover, at the copper concentration of 500 mg/l no barley grain sprouting activity was detected. The highest content of total phenols was observed when copper concentration in the solution was 50 mg/l. DOI: http://dx.doi.org/10.5755/j01.ct.62.4.3411
The application of hierarchical cluster analysis for clasifying horseradish genotypes (Armoracia rusticana L.) roots
Horseradish (Armoracia rusticana L.) is a perennial herb belonging to the Brassicaceae family; it contains biologically active substances such as phenolic compounds. The aim of the present research was to clasify horseradish root genotypes, based on the total phenol content and antioxidant properties, using the hierarchical cluster analysis (HCA), and to compare them with clusters obtained from data of the molecular random amplified polymorphic DNA (RAPD) analysis. Plant phenolic compounds are among the most important primary antioxidants. The phenolic composition of plants is affected by different factors such as variety, genotype, climate, harvest time, storage, processing. Nine genotypes of horseradish roots harvested at three different times in the period from August to November 2011 were used. Several statistical methods can be used to assess differences in the horseradish genotypes. Using a univariate statistical analysis and standard deviations for each analyzed variable does not help to get a complete insight into the complex analysis. Multivariate statistical methods are appropriate tools for the analysis of a complex data matrix. The hierarchical cluster analysis (HCA) used in the current research is a simple way of grouping the set of available data by their similarities according to a set of selected variables. No similarities were found by clustering the genotypes according to the content of biologically active compounds and molecular analyses. DOI: http://dx.doi.org/10.5755/j01.ct.62.4.3410
Functional properties of powdered β-lactoglobulin – cholecalciferol complexes
The objective of the present study was to assess the influence of the drying method on selected physical properties of powdered complexes of β-lactoglobulin – cholecalciferol (β-LG – vitamin D3) with addition of carbohydrates. Improved wettability and reduced hygroscopicity were observed for β-LG – vitamin D3 complexes with addition of carbohydrates. Powdered complexes of β-LG – vitamin D3 with/without addition of lactose/trehalose obtained by freeze-drying were characterised by a larger particle size and better wettability as compared to spray-dried powders. The stability of amorphous powders depends on the material composition and storage conditions. The results showed that addition of carbohydrates, lactose or trehalose had a similar water sorption but different crystallization properties. In the case of β-LG – vitamin D3 complexes, the crystallization of carbohydrates, especially trehalose crystallization, was delayed. DOI: http://dx.doi.org/10.5755/j01.ct.62.4.3318
The influence of sodium hydroxide on the rheological properties of pastes and gels of potato, corn and wheat starches
The subject of the study was corn, wheat and potato starch before and after treatment with sodium hydroxide solution, with the aim to evaluate whether this solution is able to remove lipids and have any effect on the rheological properties of starch pastes and gels. Applying the DSC method, it was noted that after the treatment with the sodium hydroxide solution, the enthalpy difference of the amylose–lipids complex formation/ disruption was lower for wheat and corn starch (32.7 % and 71.9 %, respectively). In case of potato starch, complexes were detected neither before nor after the treatment. The study of the rheological properties showed that after the treatment of wheat and corn starch, their gels became softer, the storage modulus (G′) decreased and the delta angle (δ) increased. At the same time, the potato starch gel had a relatively low G′ modulus and a high delta angle even without treatment, and the treatment itself had a minor effect on its properties. DOI: http://dx.doi.org/10.5755/j01.ct.62.4.3229
Sugar factory lime usage for the production of feed phosphates
Various mineral phosphates for the production of feed phosphates are widely used. The chemical composition of mineral phosphates is an important requirement. When mineral phosphates contain harmful elements such as lead, mercury, cadmium, fluorine, an additional expensive technological treatment of the raw material is required. For the production of feed phosphates as an alternative material, sugar factory lime (SFL) is of interest. Most of this waste consists of calcium carbonate containing up to 50 % of CaO as well as a small content and a low concentration of useful microelements such as Fe, Cu, Zn, Mn, Co. The aim of this work was to investigate the possibility of obtaining feed phosphates using SFL. The influence the SFL and phosphoric acid ratio, the temperature and duration of treatment on the chemical properties of produced feed phosphates was investigated. The optimum temperature and the duration of SFL treatment by phosphoric acid, the SFL : H3PO4 ratio and the composition of the product were determined. The results have shown that SFL can be used for the production of feed phosphates. DOI: http://dx.doi.org/10.5755/j01.ct.62.4.3227
Correlations between meat quality traits and cholesterol content in M. longissimus dorsi in pigs of different genotypes
The objective of the study was to estimate a correlation between meat quality traits and cholesterol content in M. longissimus dorsi of pigs. The correlation between meat quality traits and cholesterol content varied from weak (0.01) to very strong (0.94). Significant phenotypic correlations were found between pH and meat colour intensity, water holding capacity, and cooking loss (p < 0.05). The lowest cholesterol amount was found in Lithuanian indigenous and the highest in Lithuanian White pig meat. A low correlation between cholesterol content and intramuscular fat content was determined (r < 0.19). Cholesterol is mostly correlated with meat colour yellowness, cooking loss, and the drip loss (p < 0.01). DOI: http://dx.doi.org/10.5755/j01.ct.62.4.3408
The influence of N-substituted β-alanines containing naphthoquinone and thiazole moieties on the growth of St. John’s Wort (Hypericum Perforatum L.) and its ability to accumulate metabolites
In recent years, the growing interest in medicinal plants and their products led the producers of pharmaceuticals to start utilizing the biomass of cultivated plants instead of collecting the biomass that naturally appears in nature. Most of these plants are grown organically; therefore, they are highly exposed to the pathogens that lower the yield of medicinal plants and modify the chemical composition of the plant extracts. The aim of this work was to evaluate and compare the effect of N-substituted β-alanine derivatives containing 1,4-naphthoquinone and thiazole fragments on the growth of St. John’s wort and its ability to accumulate valuable metabolites. Five β-alanine compounds were used during this research, and three well known compounds (3-indolylacetic acid, 2-methyl-1,4-naphthoquinone, N-phenyl-N-tiocarbamoyl-β-alanine) were chosen for comparison. The shoots of medicinal plants were evaluated for their growth after treatment with different concentrations (0.25–5 mg/l) of β-alanine derivatives. The highest growth-regulating effect on Hypericum perforatum L. was shown by N-(1,4-naphthoquinon-2-yl)-β-alanine (1) (1 mg/l) and N-phenyl-N-[(5-(phenyl)methylidene)-4-oxo-2(4H)-thiazolyl]-β-alanine (5) (1 mg/l); therefore, they were chosen for the further research. The shoots of St. John’s wort were grown on the Murashige & Skoog (MS) medium supplemented with compounds 1 and 5. The highest amount of pigments (carotenoids, chlorophylls a and b) after a short period of cultivation was obtained in the leaves of shoots grown on the MS + 1 (1 mg/l) medium; however, treatment with compound 5 increased the content of pigments after a long period (8–9 weeks) of cultivation. According to the results, the highest content of phenolics was found in shoots grown on a medium supplemented with compound 5. DOI: http://dx.doi.org/10.5755/j01.ct.62.4.3409
Mechanical properties of Mn coatings, electrodeposited from sulphate electrolyte with Te(VI) additive at different temperatures
The influence of electrolyte temperature and cathode current density on the microhardness and tensile stress of electrodeposited Mn coatings have been investigated. It has been determined that mostly hard coatings were electrodeposited from the acid manganese electrolyte with the Te(VI) additive at 20 °C using a low current density (2 A×dm–2). Mn coatings of the same high hardness were electrodeposited using a higher current density (15 A×dm–2) and at a higher electrolyte temperature (70 °C). Supposedly, the hardness is related to the structure and composition of coatings very closely. It has been assumed that Te incorporates in the Mn coatings during the initial stage of electrolysis and changes their structure and morphology. This leads to the maximum tensile stress values of the relatively thick coatings (1–2 mm). DOI: http://dx.doi.org/10.5755/j01.ct.62.4.3317
Regularities of photoelectrochemical oxidation of glycerol using electrophoretically deposited TiO2 coatings on steel
The aim of this work was to study glycerol photoelectrochemical oxidation by using electrophoretically deposited nanosized TiO2 coatings on AISI 304 type stainless steel. The structure and morphology of the prepared coatings were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). It has been determined that the coatings contain 73 % of anatase and 27 % of rutile. The average crystallite size was calculated to be 21 and 54 nm for anatase and rutile, respectively. The photoelectrochemical behaviour of TiO2 coatings was investigated by photovoltammetry. The n-type TiO2 coatings were found to generate the photocurrents which are greatly enhanced by the presence of glycerol in 0.1 M Na2SO4 aqueous electrolyte. An increase in glycerol concentration causes a decrease in the photocurrent. The presence of pure glycerol results in higher photocurrents as compared with the technical glycerol. DOI: http://dx.doi.org/10.5755/j01.ct.62.4.3228
APPLICATION OF ION-EXCHANGE RESINS FOR REMOVING SULPHATE IONS FROM ACIDIC SOLUTIONS
The removal of sulphate ions from different types of wastewater is an environmental challenge faced by several industrial sectors such as the mining, petrochemical or metallurgical industry. Most of the current existing options are inefficient and economically unviable, particularly for acid mine drainage (AMD), where the low pH and high concentrations of heavy metals and sulphates are limiting for these processes. This work is focused on ion-exchange as one of the most common treatment methods for AMD treatment. Ion-exchange represents a very powerful technology where one or more undesirable contaminants are removed from the aqueous environment by exchange with another substance. The ideal ion-exchange solution for sulphate reduction is one that combines both anionic and cationic resins. The paper presents the results from ion-exchange experiments by the synthetic ion-exchange resin and the AMBERLITE MB20 for SO42– removal from a model solution. The efficiency of the AMBERLITE MB20 resin for SO42– removal from the model solution H2SO4 was higher than of the PUROLITE MB400, and its efficiency decreased with increasing the concentration of sulphates from 86.6 % for the concentration 100 mg/L to 66.9 % for the concertation 1000 mg/L. DOI: http://dx.doi.org/10.5755/j01.ct.68.1.15004
ACCUMULATION OF RESIDUAL ENERGY OF AN EXPERIMENTAL STOVE AFTER BURNING
Engineers, architects and designers increasingly rely on mathematical constructs incorporated into civil engineering programs to explain physical and mechanical phenomena. A low thermal diffusivity represents a material’s ability to slow down the rate of heat transfer due to heat absorption and storage, so that high thermal masses are desirable. The thermal inertia of the earth structures in general is an under-researched topic, especially regarding their unique ability to delay and attenuate temperature responses. The paper uses a high temperature difference example, in the form of an experimental stove, to highlight the benefits of a thermal mass. Countries such as Austria, the Czech Republic and Slovakia are known for their ornate historical masonry stoves that grace many stately houses, castles and palaces. They were stoked once or twice daily and radiated heat constantly during the winter months. This guild developed and thrived until the advent of modern HVAC systems in the 20th century. The paper sets out to monitor the temperature difference produced by stoking and firing a simplified experimental stove and analyses the decrease in temperature until it approaches a fixed room temperature. Temperature and heat flux are then observed to determine the total residual heat energy after burning, and the results are discussed in the conclusion. Inspired by these sound principles, based on lessons from the vernacular building traditions that have been used for centuries, the output of this work could be used in future to design an appropriate amount of the thermal mass to maximize thermal efficiency in fireplaces and stoves and as a precedent for a synergetic combination of the thermal mass and renewable energy sources. DOI: http://dx.doi.org/10.5755/j01.ct.68.1.15006
EFFECT OF VARIOUS CARBOHYDRATE ADDITIVES ON PEROXIDE FORMATION IN FAT FOR CONFECTIONERY PRODUCTION
A lot of ingredients used for food may have their own antioxidant activity. For this reason, it is necessary to explore the effect of natural antioxidants and non-specific antioxidants of some confectionery ingredients for the stabilization of food products against the formation of peroxides. The aim of the study was to verify the effect of some carbohydrates in preventing the formation of peroxides in fat for the confectionery production and to prove that the quality and shelf-life of confectionery products are affected by ingredients used in the compositions of confectionery products and by compounds that are formed in their interaction. Butter was used as the basic ingredient to study the fat stability. The effect of carbohydrates used in confectionery and their interaction with butter was examined, and the peroxides were determined. The effect of vanillin in facilitating or preventing the above-mentioned interaction was also determined. Peroxides were determined by means of the standard LVS EN ISO 3960:2010. It was established that practically all carbohydrates decreased the formation of peroxides in the samples. The quantity of peroxides in butter with 30 % of sucrose was by 10.7 % lower, with 30 % of glucose – by 41.3 % lower comparing to butter without additives after the samples had been stored for 30 days at 28 ± 2 °C. The most effective after 30 days of storage was sorbitol which decreased the formation of peroxides by 65.3 %. The same activity was also established for vanillin. Its antioxidant activity was similar to the activity of sugars, and therefore their summary activity reduces in confectionery products. It is established that the activity of sugars is quite temporary, and with increasing the quantity of peroxides in the product it decreases or completely disappears. DOI: http://dx.doi.org/10.5755/j01.ct.68.1.18879
BACTERIA OF THE GENUS BACILLUS AS A METHOD OF DIRECTED MODIFICATION OF POLYCAPROAMIDE FIBERS
In this paper, studies are presented that indicate the feasibility and effectiveness of the use of the genus Bacillus microorganisms for the directional modification of physicomechanical properties (strength, nominal stretching) of polycaproamide fibers and the production of high-strength polymer-matrix composites. Bacteria of the genus Bacillus can affect the structure of the surface of the fibers by increasing the nanoroughness and the amorphous layer. It is possible to use Bacillus brevis, Bacillus subtilis, Bacillus mesentericus and others strains to improve the consumer characteristics by the direct biodegradation of polycaproamide fibers. DOI: http://dx.doi.org/10.5755/j01.ct.68.1.18878
THE INFLUENCE OF THE SILICA/SODIUM RATIO ON THE FLY ASH GEOPOLYMER BINDER
This article investigates the properties of a geopolymer, an alternative binding material to the ordinary Portland cement (OPC), and their dependence on different SiO2/Na2O ratios in the system. To make the geopolymer polish coal burning fly ash consisting mainly of amorphous SiO2 and Al2O3, it was activated with a NaOH solution. While many researches have been done on the Si/Al ratio influence, not many studies have examined the activator solution influence on geopolymer properties. Samples were made with 8 different mix compositions with the SiO2/Na2O ratio varying within 0.8–3.1. The samples were tested for compressive strength after 7, 14 and 28 days of curing. The mineral composition of each set mix was examined with XRD. Samples with the SiO2/Na2O ratio equal to 2.0 showed the highest compressive strength. The XRD of these samples showed the presence of low-crystallinity hydrosodalite and a small amount of mullite and quartz. The acceptable strength was shown by samples with the SiO2/Na2O ratio in the range of 1.5–2.5. Samples with the ratio beyond this range failed to produce enough of the necessary binding agents. DOI: http://dx.doi.org/10.5755/j01.ct.68.1.18873