Mineral Salt Solution Research Articles

Influence of Process Liquids on the Formation of Strengthened Nanocrystalline Structures in Surface Layers of Steel Parts during Thermo-Deformation Treatment

The results of the influence of a range of process liquids on the formation of strengthened nanocrystalline structures in the surface layers of steel samples with different carbon content during thermo-deformation treatment are presented. The liquids were mineral oil; mineral oil with active additives containing polymers; water; and an aqueous solution of mineral salts based on magnesium and calcium chlorides. The thickness and hardness of the nanocrystalline layer increased with increasing steel carbon content. The thickness and microhardness of Steel C45 are 230–240 μm and 8.6 GPa, respectively, when using mineral oil with AAP, 110–120 μm and 7.2 GPa, respectively, when using mineral oil alone, and for steel CT80 when using mineral oil, they are 180–200 μm and 9.1 GPa, respectively (C45 and CT80 refers to engineering steels). The process liquid is decomposed into its component chemical elements by the high temperatures and pressures in the contact zone of the tool with the treated surface. It also gives off active hydrogen, which diffuses into the surface layer of the metal and significantly affects its formation. It was established that the greatest thickness and hardness of the layers were obtained after processing pre-hydrogenated samples. The choice of process fluid is critical during thermo-deformation treatment.

The potential of Serratia marcescens in Bioremediation of Crude-oil Polluted Soil

Bioremediation, which involves the use of microorganisms, is an environmentally friendly approach in restoring crude-oil polluted environments. The use of Serratia marcescens (SM) in bioremediation of crude-oil polluted soil was investigated in this study. Soil from a farm was inoculated in nutrient broth for bacterial enrichment. The broth culture was inoculated on nutrient agar and incubated at ambient temperatures (27 – 32 °C). Bacterial isolates with red colonies were selected and identified. Identified SM was used in preparing bacterial-mineral-salts suspension. The bioremediation experiment consisted of two setups: Control (CT) and setup treated with SM (TSM). Both setups contained crude-oil polluted soil. Mineral-salt solution and the bacterial-mineral-salt suspension were added to setup CT and TSM, respectively. Total hydrocarbon concentration (THC), total heterotrophic bacteria (THB), hydrocarbon utilizing bacteria (HUB), total fungi (TF), and hydrocarbon utilizing fungi (HUF) in the setups were determined at various times. About 38.3 % and 46.5 % THC reduction were achieved in setup CT and TSM, respectively. The percentage of THB that are HUB was higher in setup TSM on day 7 (8.8 %) and day 28 (4.4 %) but higher in setup CT on day 14 (1.7 %) and day 21 (6.6 %). The percentage of TF that are HUF was higher in setup TSM on day 14 (98.0 %) and on day 28 (41.6 %) but higher in setup CT on day 21 (85.3 %). It is concluded that SM has a potential for use in bioremediation of crude-oil polluted soil

PHASE CONCENTRATION EQUILIBRIUM DURING DRYING COLLOID CAPILLARY-POROUS MATERIAL - PEA

In this work, we studied experimentally the phase concentration equilibrium during drying of a colloidal capillary-porous material - peas. The studies were carried out by a static (exsicator) method using saturated aqueous solutions of mineral salts, with the help of which certain relative air humidity was created in the desiccators. To establish equilibrium, the samples were kept in desiccators for one month. The values of relative air humidity over salt solutions at the corresponding temperatures were found from the well-known Schneider diagram. Moisture desorption isotherms were determined, for which high-moisture pea samples were placed in exsicators. The experiments were carried out at three temperatures: 30, 40 and 50 °C. According to the measurement data, moisture desorption isotherms were constructed in the coordinates "relative air humidity - equilibrium moisture content of the material." The resulting desorption isotherms were described by the Henderson equation, for which the values of the coefficients of this equation were found and their statistical evaluation was given. The data on the balance of peas were compared with similar data for other plant colloidal capillary-porous materials: vegetables (carrot and beet cuts), grain crops (rye, wheat and corn grains), and vegetable seeds. A significant influence of the type of culture on the equilibrium moisture content of the material during drying is shown, while the intraspecific influence on the equilibrium moisture content is less important. The obtained data on moisture desorption isotherms during drying can be used for engineering calculations of the kinetics of drying pea grain and for choosing the temperature and humidity conditions for its storage after drying.

Interaction between Hexametaphosphate, Other Active Ingredients of Toothpastes, and Erosion-Abrasion in Enamel in vitro

Sodium hexametaphosphate (HMP) as toothpaste additive is claimed to reduce erosive tooth wear and to stabilize stannous ions. However, little is known about the impact of concentration and its interactions with fluoride (F) or stannous+fluoride ions (F/Sn) on enamel erosion and erosion-abrasion. In a 10 day cyclic in vitro erosion-abrasion model, 320 flat human enamel specimens were divided into ten groups (n = 32 each) and daily subjected to six erosive challenges (0.5% citric acid, 2 min) and two toothpaste suspension applications (2 min, 1:3 F-free toothpaste:mineral-salt solution, 0.23% sodium gluconate). Half of specimens per group were additionally brushed twice/day (200 g, 15 s) during suspension immersion. Nine suspensions contained HMP (0.25%, 1.75%, 3.25%), either on its own or combined with F (373 ppm F⁻) or F/Sn (800 ppm Sn²⁺, 373 ppm F⁻). One suspension contained sodium gluconate only (NegContr). After 10 days, specimens’ surfaces were analysed with profilometry, energy dispersive X-ray spectroscopy, and scanning electron microscopy. Tissue loss (µm, mean ± standard deviation) in NegContr was 10.9 ± 2.0 (erosion), 22.2 ± 1.6 (erosion-abrasion). Under erosive conditions, only 0.25% HMP in any combination and 1.75% HMP with F/Sn reduced loss significantly (−28% to −54%); 3.25% HMP without F and F/Sn increased loss significantly (+35%). With additional abrasion, no suspension reduced loss significantly compared to NegContr, instead, in groups without F and F/Sn or with 3.25% HMP loss was increased (+15% to +30%). Conclusively, at higher concentrations, HMP increased erosive tooth wear and seemed to reduce anti-erosive effects of fluoride and stannous ions.

Bioremediation of diesel oil: potential use of bacteria consortium Lactobacillus fermentum and Clostridium beijerinckii in degrading Total Petroleum Hydrocarbon (TPH)

Diesel oil is a major petroleum-refined product known as the primary environmental pollutant due to its toxic complex hydrocarbons and difficulty in decomposing naturally. This study aims to determine the efficiency of TPH (Total Petroleum Hydrocarbon) removal in the bioremediation process of diesel oil pollution by utilizing a bacteria consortium of Lactobacillus fermentum and Clostridium beijerinckii as biocatalysts. The diesel oil degradation test was conducted on a laboratory scale using Stone Mineral Salt Solution (SMSs) liquid media with a batch system (limited culture). The temperature was set at 30°C with a rotation speed of 150 rpm for 10 days. Different treatments of pH (5, 7, 9) and contact time (10, 20, 30 days) were applied to varied diesel oil concentrations (5, 10, 20%, v/v). The oil components were measured using Gas Chromatography-Flame Ionization Detector. Diesel oil samples were put into SMSs containing 10% bacterial consortium and 10% NPK fertilizer. The sensitivity test showed that the bacterial consortium was resistant, proven by the absence of an inhibition zone around the disc paper area containing diesel oil. The highest TPH removal efficiency found was 97.3% when 5% diesel oil was degraded by the bacterial consortium at pH 7 for 20 days. This study proves that the bacterial consortium can be recommended in bioremediation to alleviate diesel oil pollution in the environment.

Reduction of the Electrical Resistance of Grounding Devices by the Use of a Soil Replacement Mixture Based on Graphite and Hydrogel to Stabilize the Electrophysical Parameters of the Soil

This article discusses the factors that affect the electrical resistance of the current spreading of the grounding device. The issue of the electrophysical parameters of the soil that affect its resistivity and the consideration of such parameters in the design of grounding devices is considered. It is shown that keeping moisture in the near-electrode space of the grounding electrode, as well as maintaining it at a certain level, facilitates improving the quality and reliability of the grounding. A relationship has been established between the ability to retain moisture and the magnitude of seasonal fluctuations in the electrical resistance of the soixl, and also the season factor, which takes into account changes under different climatic environmental conditions. The issues of application of various methods of reducing the resistivity of the soil during mounting of grounding devices are considered. One of the main ways to reduce ground resistance is the use of solutions of various mineral salts. This method is not optimal, as it accelerates the corrosion processes in the materials of the ground electrodes. Therefore, the paper also considers other ways to reduce the resistance of the ground loop; in particular, the authors propose a method for reducing the resistance of a grounding device based on the method of partial replacing the soil in the near-electrode region with a mixture with a lower resistivity capable of collecting moisture based on graphite and hydrogel. This type of mixture is environmentally friendly when used, as well as it is non-aggressive to the material of the ground loop. The principle of operation of this mixture is based on the fact that the hydrogel makes it possible to stabilize the moisture at the site of laying the circuit, while graphite increases the overall conductivity of the mixture. The paper presents the results of laboratory studies, which have been carried out in accordance with GOST 9.602–2016. For this purpose, control samples were placed in containers made of a non-conductive material (plexiglas) and dependence of resistivity on moisture, temperature, specific content of graphite and hydrogel was measured. The article presents graphs of the dependences of the mixture specific resistance on moisture, temperature, and the quantitative content of the hydrogel. From the results obtained, it can be concluded that the mixture in can be used in the energy sector to improve the reliability of electrical installations and ensure electrical safety.

Process optimization of malachite green degradation by mixed biofilm positive bacteria: Application of Box–Behnken designs, RSM and whole genome sequences analysis

Bacterial biofilm positive strains recovered from engine oil polluted-soil was investigated for its capacity to remove malachite green (MG) in mineral salt solution. Box–Behnken designs combining four factors (glucose, yeast extract, temperature and agitation) with three levels (−1, 0, +1) was used to found the best biotic and abiotic conditions for MG removal. The biodegradation potential of the selected microbial consortium was also confirmed using analytical techniques. Then, whole genome sequencing (WGS) analysis were performed to detect genes related to biofilm formation and chemicals biodegradation. Our results showed that the selected strains (G5, G13 and G15) were able to form biofilm on congo red agar plates developing almost black, very black and almost black colonies respectively. Experimental results using Box-Behnken designs showed that decolorization rate of MG reach 89.35% in these optimized conditions: glucose (2%), yeast extract (1%), temperature (40 °C), and agitation (150 rpm). Molecular investigation revealed that the isolated strains were identified as Cronobacter sakazakii G5, Enterobacter hormaechei G13, and Klebsiella pneumoniae G15 based on the whole genome sequences . Whole genome sequences analysis demonstrated the presence of genes involved in biofilm formation as well as dyes and chemical detoxification. The findings presented here provide useful information for development an efficient microbial consortium, formed by adherent bacteria, able to remove dye from coloured wastewater.

Aquatic Ferrous Solutions of Prebiotic Mineral Salts as Strong UV Protectants and Possible Loci of Life Origin.

Liposomes are lipid-bilayer vesicles that spontaneously self-assemble from fatty acids (or other amphiphiles) in water by encapsulating surrounding aqueous media. After British scientist Alec Bangham described this phenomenon in the early 1960s, they became a prominent participant in the hypotheses on life origin, particularly in the Lipid World model. A novel scenario of self-sustained Darwinian liposome evolution is based on ever-present natural phenomena of cyclic day/night solar UV radiation and gravitational submersion of liposomes in the Archean aqueous media. One of the assumptions of the hypothesis is the UV-shielding ability of the Archean waters that could protect the submerged liposomes from the damaging solar UV radiation. To corroborate the idea, we measured UV absorption in aquatic solutions of several ferrous mineral salts assumed to be present in Archean pools. Single-agent solutions of simple salts such as FeCl2-iron dichloride, FeCl3-iron trichoride, Fe(NO3)3-ferric nitride, NH4Fe(SO4)2-ferric ammonium sulfate, and (NH4)5[Fe(C6H4O7)2]-ferric ammonium citrate were tested. These direct measurements of UV light absorption supplement and reinforce the proposed hypothesis.

Bioremediation of iron and manganese heavy metal polluted soil by mixed culture of Acetobacter tropicalis and Lactobacillus fermentum

The research aim was to determine the growth response of mixed cultures of Acetobacter tropicalis and Lactobacillus fermentum in Stone Mineral Salt solutions (SMSs) and soil containing Acid Mine Drainage (AMD) in controlled batches. The first stage was the cultivation in SMSs followed by preparation of the pollutant source and sensitivity test. The second phase was the removal of heavy metals from iron and manganese in AMD by mixed bacterial cultures in SMSs with the contact time for 48, 96, 144, 192 hours, and pH 2, 3, 5, 7. The third stage was the removal on soil media with the same contact time. Research result showed that the sensitivity test of bacterium was resistant to heavy metals iron and manganese. The highest removal efficiency of iron and manganese was 94.89% at a contact time of 96 hours, while the highest removal efficiency at pH 7 was 93.79%. The removal of iron and manganese heavy metals on soil had a removal efficiency of 69.91% at a contact time of 144 hours. This study showed that a mixed culture of Acetobacter tropicalis and Lactobacillus fermentum could be an effective bacterium in removing heavy metals from iron and manganese in AMD-contaminated soil.

Phenylalanine Losses in Neutralization Dialysis: Modeling and Experiment.

A non-steady state mathematical model of an amino acid (phenylalanine (Phe)) and mineral salt (NaCl) solution separation by neutralization dialysis (ND) carried out in a batch mode is proposed. The model takes into account the characteristics of membranes (thickness, ion-exchange capacity, and conductivity) and solutions (concentration, composition). As compared to previously developed models, the new one considers the local equilibrium of Phe protolysis reactions in solutions and membranes and the transport of all the phenylalanine forms (zwitterionic, positively and negatively charged) through membranes. A series of experiments on ND demineralization of the NaCl and Phe mixed solution was carried out. In order to minimize Phe losses, the solution pH in the desalination compartment was controlled by changing the concentrations of the solutions in the acid and alkali compartments of the ND cell. The validity of the model was verified by comparison of simulated and experimental time dependencies of solution electrical conductivity and pH, as well as the concentration of Na+, Cl- ions, and Phe species in the desalination compartment. Based on the simulation results, the role of Phe transport mechanisms in the losses of this amino acid during ND was discussed. In the experiments carried out, the demineralization rate reached 90%, accompanied by minimal Phe losses of about 16%. Modeling predicts a steep increase in Phe losses when the demineralization rate is higher than 95%. Nevertheless, simulations show that it is possible to achieve a highly demineralized solution (by 99.9%) with Phe losses amounting to 42%.

Selective enrichment, identification, and isolation of diclofenac, ibuprofen, and carbamazepine degrading bacteria from a groundwater biofilm

Diclofenac, ibuprofen, and carbamazepine are three of the most widely detected and most concerning pharmaceutical residues in aquatic ecosystems. The aim of this study was to identify bacteria that may be involved in their degradation from a bacterial biofilm. Selective enrichment cultures in mineral salt solution containing pharmaceutical compounds as sole source of carbon and energy were set up, and population dynamics were monitored using shotgun metagenome sequencing. Bacterial genomes were reconstructed using genome-resolved metagenomics. Thirty bacterial isolates were obtained, identified at species level, and tested regarding pharmaceutical biodegradation at an initial concentration of 1.5 mg l−1. The results indicated that most probably diclofenac biodegrading cultures consisted of members of genera Ferrovibrio, Hydrocarboniphaga, Zavarzinia, and Sphingopyxis, while in ibuprofen biodegradation Nocardioides and Starkeya, and in carbamazepine biodegradation Nocardioides, Pseudonocardia, and Sphingopyxis might be involved. During the enrichments, compared to the initial state the percentage relative abundance of these genera increased up to three orders of magnitude. Except Starkeya, the genomes of these bacteria were reconstructed and annotated. Metabolic analyses of the annotated genomes indicated that these bacteria harbored genes associated with pharmaceutical biodegradation. Stenotrophomonas humi DIC_5 and Rhizobium daejeonense IBU_18 isolates eliminated diclofenac and ibuprofen during the tests in the presence of either glucose (3 g l−1) or in R2A broth. Higher than 90% concentration reduction was observed in the case of both compounds.

Identification and quantification of the sea spray effect on isotopic systems in α-cellulose (δ13C, δ18O), total sulfur (δ34S), and 87Sr/86Sr of European beach grass (Ammophila arenaria, L.) in a greenhouse experiment

The sea spray effect can severely influence the isotopic signature of terrestrial individuals in coastal regions. To further specify this effect, beach grass was grown in a greenhouse under controlled environmental conditions and sprayed with mineral salt solution containing different mineral salts but only traces of NaCl (group 1). Another group of plants was sprayed with salty water from the Schlei inlet and the Baltic Sea, respectively (group 2). Control plants were only sprayed with tap water.Isotope analyses were conducted on the unwashed and washed plants (δ13Ccellulose, δ18Ocellulose, δ34Stotal S, 87Sr/86Sr), soil (δ18Osulfate, δ34Ssulfate, 87Sr/86Sr), and spray as well as irrigation water (δ18Osulfate, δ34Ssulfate, 87Sr/86Sr). Moreover, elemental analyses were performed on the water samples.The sea spray effect was visible in all isotopic systems under study. The uptake of SO42−, HCO3−, and Sr2+ directly affected plants of group 1, while plants of group 2, sprayed with salty water, additionally showed salinity stress in the case of α-cellulose and total sulfur due to biochemical reactions of the plants. Very high concentrations in HCO3− or SO42− also affected the plants' isotopic signatures. The impact of the sea spray and additional stress reactions were quantified.Our study is the first experiment creating an artificial sea spray effect in a greenhouse. This experiment for the first time enables the identification and quantification of the sea spray effect in environmental samples. The marine signature taken up by the plants and recorded by the investigated isotopic systems is apparently high and should have an impact on the isotopic fingerprints of animal consumers at the coast, as evidenced for archaeological animals from the Viking Haithabu and the early medieval Schleswig sites located close to the Baltic Sea. This result demonstrates the potential of greenhouse experiments as an isotopic predictor of the past local sea spray effect.

Nocardioides carbamazepini sp. nov., an ibuprofen degrader isolated from a biofilm bacterial community enriched on carbamazepine

From the metagenome of a carbamazepine amended selective enrichment culture the genome of a new to science bacterial species affiliating with the genus Nocardioides was reconstructed. From the same enrichment an aerobic actinobacterium, strain CBZ_1T, sharing 99.4% whole-genome sequence similarity with the reconstructed Nocardioides sp. bin genome was isolated. On the basis of 16S rRNA gene sequence similarity the novel isolate affiliated to the genus Nocardioides, with the closest relatives Nocardioides kongjuensis DSM19082T (98.4%), Nocardioides daeguensis JCM17460T (98.4%) and Nocardioides nitrophenolicus DSM15529T (98.2%). Using a polyphasic approach it was confirmed that the isolate CBZ_1T represents a new phyletic lineage within the genus Nocardioides.According to metagenomic, metatranscriptomic studies and metabolic analyses strain CZB_1T was abundant in both carbamazepine and ibuprofen enrichments, and harbors biodegradative genes involved in the biodegradation of pharmaceutical compounds. Biodegradation studies supported that the new species was capable of ibuprofen biodegradation. After 7 weeks of incubation, in mineral salts solution supplemented with glucose (3 g l−1) as co-substrate, 70% of ibuprofen was eliminated by strain CBZ_1T at an initial conc. of 1.5 mg l−1.The phylogenetic, phenotypic and chemotaxonomic data supported the classification of strain CBZ_1T to the genus Nocardioides, for which the name Nocardioides carbamazepini sp. nov. (CBZ_1T = NCAIM B.0.2663 = LMG 32395) is proposed.To the best of our knowledge, this is the first study that reports simultaneous genome reconstruction of a new to science bacterial species using metagenome binning and at the same time the isolation of the same novel bacterial species.

The use of H-form clinoptilolite to preconcentrate trace amounts of Nd(III) from aqueous solution under dynamic conditions

Rare earth elements (REE) are vital in the industry, particularly in the manufacturing of high-tech products. REE are emitted in enormous amounts into the environment as a result of their increased use in industry. The sorption technique is one of the most efficient ways to extract rare earth elements in low quantities. The results of a dynamic study of the sorption capabilities of the H-form of Transcarpathian clinoptilolite towards Nd(III) are presented in this work. X-ray diffraction, FT-IR, zeta potential analysis, and potentiometric titration were used to analyze the sorbent. The breakthrough capacity of H-clinoptilolite toward Nd(III) was 3.1 mg g−1 under ideal conditions (pH = 7.5, sorbent thermal treatment temperature: t = 150 °C). The desorption efficiency of Nd(III) has been investigated using acids and different mineral salt solutions. The optimum desorbing agent appeared to be acidified (pH 4) 1 M KNO3 solutions. A method for preconcentrating trace amounts of Nd(III) using acid-modified Transcarpathian clinoptilolite in a solid-phase extraction mode is proposed, followed by spectrophotometric measurement of this rare earth element.

Development of a bacterial consortium from Variovorax paradoxus and Pseudomonas veronii isolates applicable in the removal of BTEX

In this study, we report on the development of a novel bacterial consortium, consisting of Variovorax paradoxus and Pseudomonas veronii isolates, applicable in the biodegradation of all six BTEX compounds (benzene, toluene, ethylbenzene, o-, m- and p-xylene) and the bioremediation of contaminated sites. The co-cultivability of the selected bacterial isolates was determined in nutrient-rich medium, as well as in BTEX amended mineral salts solution using Terminal Restriction Fragment Length Polymorphism (T-RFLP) and CFU determinations. BTEX biodegradation capacity of the two-strain consortium was assessed in mineral salts solution, where a series of BTEX depletions and supplementations occurred, as well as in a real, BTEX polluted environmental sample (contaminated groundwater) in the presence of the autochthonous bacterial community. The obtained results indicated that the developed bacterial consortium is very efficient in BTEX biodegradation. Under laboratory conditions, the acclimatized bacterial consortium completely degraded the BTEX mixture with a concentration as high as 20 mg l−1 in a mineral salt medium within a short span of 6 h. Close to in situ groundwater conditions (incubated at 15 °C under static conditions in the absence of light), groundwater microcosms containing the autochthonous bacterial community inoculated with the developed bacterial consortium showed more efficient toluene, o-, m-and p-xylene biodegradation capacity than microcosms containing solely the native microbial population originally found in the groundwater. In the inoculated microcosms, after 115 h of incubation the concentration (~ 1.7 mg l−1 each) of o-, m- and p-xylene decreased to zero, whereas in the non-inoculated microcosms the concentration of xylene isomers was still 0.2, 0.3 and 0.3 mg l−1, respectively. The allochthonous bioaugmentation of the contaminated groundwater with the obtained inoculant was successful and manifested in a better BTEX degradation rate. Our results suggest that the obtained bacterial consortium can be a new, stable and efficient bioremediation agent applicable in the synergistic elimination of BTEX compounds from contaminated sites.

Evaluation of enzymatic production of hydrolases and oxyredutases by Fusarium pseudocircinatum and Corynespora torulosa isolated from caesarweed (Urena lobata L., 1753)

This work evaluates the enzymatic production of hydrolases and oxireductases by endophytic fungi isolated from leaves of the caesarweed (Urena lobata L.), which is a perennial plant that is well adapted to the Amazon floodplains region, being and is widely used in the production of hessian sacks and other products of natural fiber. Fungi strains Fusarium sp. (1290) and Corynespora sp. (1291) were reactivated, and had their DNA extracted and sequenced to obtain molecular identification. For enzymatic production, dried and ground caesarweed was used as a substrate in the mineral salt solutions Manachini and GLBN 40 over during 10 days of submerged cultivation (CS) under agitation. The CA was vacuum filtered daily with a 0.22 µm Millipore membrane to obtain enzymatic extracts, from which the activities of FPase, xylanase, CMCase, β-glycosidase, pectinase, laccase, manganese peroxidase (MnP) and lignin peroxidase (LiP) were evaluated. Lines strains 1290 and 1291 were identified as F. pseudocircinatum and C. torulosa, respectively, the latter being the best producer of laccase (8,691 U/L), MnP (5,353 U/L), β-glycosidase (0.328 U/mL) and CMCase (0.351 U/mL) and the fungus F. pseudocircinatum was the best producer of FPase (1.294 U/mL), xylanase (12.052 U/mL) and pectinase (0.183 U/mL). No LiP activity was detected for either of the strains. The results showed that the strains used are promising for the production of seven of the eight quantified enzymes, and these enzymes are of interest to several industrial sectors.

ИССЛЕДОВАНИЕ РАВНОВЕСНОГО ВЛАГОСОДЕРЖАНИЯ НАРЕЗКИ СВЕКЛЫ КАК ПАРАМЕТРА, ИСПОЛЬЗУЕМОГО В АГРОИНЖЕНЕРНЫХ РАСЧЕТАХ

To make the agroengineering analysis of the drying process of sliced beets, it is necessary to know its moisture equilibrium. Due to the lack of the reference data for elevated temperatures at which drying of this material is carried out, the isotherms of moisture desorption were obtained and analyzed by the experimental static (desiccator) method for sliced beetroot at temperatures of 30, 40 and 50°C. The authors used saturated solutions of various mineral salts to get specific values of the relative air humidity in desiccators. They found the relative air humidity indicators in the space above them according to the well-known diagram ofA. Schneider. The obtained moisture desorption isotherms are S-shaped, typical for capillary-porous colloidal materials, and they correspond to the fourth type of sorption isotherms according to the Brunauer classification. For the convenience of engineering analysis, they are described by the Henderson equation, which can be used to determine the values of the equilibrium moisture content of a material at various values of relative humidity and temperature. The authors have found values of the constants for this equation. A statistical assessment of the approximation reliability of the experimental data made by the Henderson equation has shown a satisfactory compliance of this equation with the experimental data. Since beetroot samples with high (natural) humidity were placed in desiccators when removing the equilibrium, the obtained isotherms are of the desorption type. They are exactly the type required to analyze the material drying process. The research results are applicable for analyzing the drying process for slicing beetroot and organizing the storage process.

ELASTOMERS WITH A HIGH CONTENT OF MODIFIED CARBOXYMETHYLCELLULOSE

The use of lactam-containing complex salts (LCS) with the functions of dispersants, apparatuses and crosslinking agents made it possible to obtain elastomers with a high (at least 300 wt.% per 100 wt.h. of rubber), containing modified carboxymethyl cellulose for the cuff of a packer device capable of performing the necessary shut-off functions in contact with highly concentrated, at least 25% aqueous solutions of mineral salts - NaCl and CaCl2. The achieved effect is expressed in the ability of LCS to disperse water-swelling polymers (GNP), to have an appreting effect on GNP particles, thereby preventing their agglomeration, as well as to create additional chemisorption bonds in the rubber matrix. As a result, a developed network of interface boundaries is obtained, which contributes to the rapid penetration of aqueous solutions of mineral salts into the array of elastomeric composition.

Synthesis and properties of vinyl benzyl alcohol copolymers with styrene

Objectives. Synthesis and study of the properties of copolymers of vinyl benzyl alcohol (VBA) with styrene with antimicrobial properties.Methods. The study employed infrared (IR) and nuclear magnetic resonance (NMR) spectroscopy, thin-layer chromatography, viscometry, and elemental analysis. The sessile drop method and the pencil method were respectively utilized to determine the contact angles and hardness of the films. The process of testing the film coatings’ resistance to the effects of molds consisted of contaminating the film coatings applied to the glass with mold spores of the All-Russian Collection of Microorganisms in a solution of mineral salts without sugar (Czapek–Dox medium).Results. Homopolymers of vinyl benzyl acetate and its copolymers with styrene were synthesized in this study. Homo- and copolymers of VBA were obtained by saponification. IR and proton NMR (1H NMR) spectroscopy determined the composition of the copolymers. Employing IR spectroscopy, the degree of saponification was monitored by the appearance of the hydroxyl group absorption band and the disappearance of the ester group absorption band. According to the IR spectroscopy data, only an insignificant (~3%) amount of ester groups remains in the saponified copolymers. The influence of the copolymers’ composition on their solubility in various solvents is demonstrated. IR spectroscopy of the copolymers revealed hydrogen-bond formation between the unreacted ester groups and hydroxyl groups formed due to the saponification. The viscometry of the solutions of mixtures of saponified and unsaponified copolymers, solutions of mixtures of saponified copolymer with polyvinyl acetate, and viscometry of saponified copolymers in various solvents all support this conclusion. These bonds’ concentration depends on the copolymer’s composition and can be controlled by the nature of the solvent from which these copolymers’ films are formed. Saponified copolymer solutions form smooth, transparent film coatings with excellent adhesion to metals and silicate glass surfaces. The contact angle of these films, like the hardness, decreases as the VBA units’ concentration in the copolymers increases and depends on the solvent polarity used to form the films. It has been demonstrated that increasing the VBA units concentration suppresses the microorganisms’ growth.Conclusions. Film coatings made of copolymers of styrene with VBA have been shown to have high biocidal activity against molds; can be used to protect structural materials and products from the effects of microorganisms.

DEGRADATION OF POLYETHYLENE PLASTIC WASTE BY INDIGENOUS MICROBIAL CONSORTIUM AND FUNGI

Aim: The aims of this research is to determine the ability of an indigenous microbial consortium to degrade Low Density Polyethylene plastics. The plastic was cut mechanically into 1 x 1 cm2 pieces because the smaller the size of the plastic, the larger the surface area. The samples are input in an Erlenmeyer flask containing indigenous microbial consortium and fungi (20% v/v) and Stone Mineral Salt solution media (80% v/v). This research lasted 10 days with a pH of 7 controlled and temperature variations of 25, 30, 35°C. As preliminary research, the sensitivity test seeks to demonstrate that the indigenous microbial consortium and fungi are resistant or insensitive to LDPE. The degradation of LDPE plastic was analyzed using gravimetric methods, Fourier Transform Infrared, and a scanning electron microscope. Methodology and results: According to the results of gravimetric and FTIR analysis, the highest removal value was at a temperature variation of 30°C. The gravimetric analysis revealed that the weight loss in LDPE plastic was 0.0082 gr to 0,0074 gr or 9.76 %, while the FTIR analysis revealed that the intensity removal result was 6,27 %. Conclusion, significance, and impact of study: Scanning Electron Microscope (SEM) analysis revealed morphological changes on the surface of LDPE plastic samples, confirming these findings. Several factors influence the changes that occur in this study's LDPE plastic samples.