2. Articole
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Item ИЗУЧЕНИЕ СОСТАВА И РАСПРЕДЕЛЕНИЯ СЕРОСОДЕРЖАЩИХ СОЕДИНЕНИЙ ПРИ ОЧИСТКЕ СТОЧНЫХ ВОД И МЕТОДЫ ИХ ОПРЕДЕЛЕНИЯ(CEP USM, 2024) Шепель, Диана; Спатару, Петру; Вишневски, АлександрSulfur distribution in wastewater, in primary sludge, in activated sludge after digestion, and in other intermediate fractions at various stages of water treatment was studied. The main contribution to the formation of volatile sulfur compounds in sewage sludge and in the wastewater itself comes from sulfates, protein compounds, glutathione, sulfolipids, and chondroitin sulfate. The analytical methods used for the determination of sulfur-containing compounds were described. Valuable information was obtained to predict further actions to detect sulfur-containing compounds in the studied objects obtained from wastewater treatment plants of the Republic of Moldova, which must be removed, as they represent an environmental hazard.Item СИНТЕЗ ПОЛИ – (1,4-ДИАМИННАФТАЛИНА)МЕТОДОМ ОКИСЛИТЕЛЬНОЙ ПОЛИМЕРИЗАЦИИ И ИЗУЧЕНИЕ ЕГО СВОЙСТВ(CEP USM, 2024) Рзаев, Рамиль; Жеру, Ион; Сукман, Наталья; Макаев, ФлюрThe aim of this study was to synthesize free of metals polymeric organic materials that possess electrical conductivity. The nanoscale poly-(1,4-diaminonaphthalene) was synthesized using the oxidative polymerization method. The reaction was carried out in a hydrochloric acid solution at 0°C, with potassium persulfate used as the oxidizing agent. The polymers were characterized using various techniques, including FT-IR, UV-Vis, TGA, NMR, EPR and SEM. It was found that the polymerization of 1,4-diaminonaphthalene occurs through the formation of N–C and N=C. UV studies revealed differences in the polymer chain conformations and polaron states. The UV-Vis spectra showed strong absorption bands at 250 and 340 nm, associated with π→ π* and n→ π* transitions, respectively. Electron Paramagnetic Resonance detected the presence of radicals in the polymer chain and established their position on the nitrogen atom. The micro-morphology study of the polymer revealed an irregular porous structure with pore sizes less than 5 μm. Additionally, it was demonstrated that the nanopolymers are thermally stable up to 140°C.Item КАТАЛИТИЧЕСКИЙ ХАРАКТЕР ЭВТЕКТИЧЕСКИХ СМЕСЕЙ В СИНТЕЗЕ ДИГИДРОПИРИМИДИНОВ(CEP USM, 2024) Чобану, Наталья; Макаев, ФлюрOne of the current trends in modern science is “green chemistry” - this is a scientific direction in chemistry, which includes any improvement in chemical processes that has a positive effect on the environment. From the point of view of “green chemistry”, which is as waste-free and environmentally friendly as possible, it is of interest to obtain ionic liquids containing various active groups, such as cyanoethyl, carboxyl, etc., and on their basis to obtain eutectic mixtures with thiourea, urea and study their catalytic properties in the synthesis of various substituted dihydropyrimidines. It is interesting that both ES and their components separately consist of pharmacophore structures and are of pharmaceutical and biological interest. Moreover, each element of the ES, as well as the ES as a whole, fully meets the modern requirements of biodegradability, bioavailability and the interests of the world ecology.Item ПОЛУСЕНИЕ ПРОИЗВОДНЫХ КЛАССА ПИРАЗОЛА ГЕТЕРОЦИКЛИЗАЦИИ 1,2,4-ТРИАЗОЛИЛЭТАНОНОВ(CEP USM, 2024) Звягинцева, Марина; Сукман, Наталья; Макаев, ФлюрIn this work the peculiarities of the heterocyclization reaction of vinyltriazoles with the participation of hydrazine hydrate in ethanol and acetic acid are considered. Within the framework of this work it was found that the nature of the formed reaction products of the interaction of vinyltriazoles with hydrazine hydrate depends on the nature of the solvent. In boiling ethanol, 4,5-dihydro-1H-pyrazolinfunctionalized 1H-1,2,4-triazole is formed. Under acetic acid conditions, along with the formation of a pair of diastereomeric substances 4,5-dihydro-1H-pyrazoline series diastereomeric substances undergoing acylation, the formation of triazolium salt of acetic acid undergoes decomposition with cleavage of 1H-1,2,4-triazole fragment and formation of 3,5-disubstituted pyrazole. The structure of the obtained compounds was confirmed by spectral data and elemental analysisItem DERIVAȚI CALCONICI CU GRUPA 4-(DIMETILAMINO)FENIL ÎN APLICAȚII FOTOVOLTAICE(CEP USM, 2024) Popuşoi, Ana; Potlog, Tamara; Robu, Ştefan; Jora, ElenaIn this paper, dye-sensitized solar cells (DSSCs) are fabricated and studied using chalconic derivatives as sensitizing dyes. The chalconic derivatives containing the 4-N,N-dimethyl group present two absorption bands with maxima located at the 241 nm and 416 nm, with maximum intensity in the visible region and absorption coefficient of the order 104 cm-1. The analysis of the current-voltage characteristics of the DSSCs with the respective chalconic derivative indicattes the best solar energy conversion efficiency (η = 0.4%), due to the fact that it has the highest absorption value in the band located in the visible region. The best short-circuits current density with value of 2.45 mA/cm2. are obtained for the DSSCs sensitized with chalconic derivative containing 4-N, N-dimethyl SH group.Item STUDIUL EXPERIMENTAL ȘI DFT AL ADSORBIȚIEI IONILOR METALICI PE SUPRAFAȚA CARBUNELUI ACTIVAT PRIN GRUPĂRI CARBOXILICE(CEP USM, 2024) Nastas, Raisa; Bălan, IolantaIn this work, the influence of solution pH, the nature of activated carbons surface chemistry and contribution of carboxylic functional groups on the adsorption of metal ions from solution have been analyzed via experimental and computational methods. The main purpose of this work was to use the computational methods to study the adsorption of hydrated metal ions on the surface of activated carbons containing carboxylic groups. The DFT/B3LYP/3-21G calculations confirm the experimental results that the acidic functional groups from the activated carbons surface play an important role in the adsorption of metals ions from solutions and revealed that the adsorption of hydrated metal ions takes place through the carboxylic groups.Item STUDIUL LEGITĂȚILOR CINETICE DE TRANSFORMARE A ACIDULUI GALIC PRIN APLICAREA PROCESELOR DE OXIDARE AVANSATĂ ÎN SISTEME MODEL(CEP USM, 2024) Mocanu, Larisa; Gonţa, Maria; Duca, GheorgheGallic acid is a naturally occurring phenolic compound. Due to its persistence and potential toxicity, presents environmental challenges. Removal of gallic acid from wastewater, allows recycling and reuse of water in various industrial processes, reducing water consumption and contributing to sustainable practices. As a result, the removal of gallic acid from aqueous model solutions was studied by applying (AOPs): AG/Fenton, AG/Fenton/UV, AG/TiO2/H2O2/UV according to different physicochemical parameters. AOPs have emerged as promising techniques due to their ability to generate highly reactive hydroxyl radicals, initiating the oxidation of GA and leading to its degradation. Based on the results obtained the kinetics degradation of GA (25 mg/L) can be described by pseudo-first-order kinetics. By comparison, it was identified that Fenton reactions offer efficient means for the oxidation of GA, leading to its degradation (50%) and mineralization (30%) after 5 min of reaction. Thus, the best initial operating conditions, for practical purposes, are [H2O2] = 5·10-4 mol/L, [Fe2+] = 1·10-5 mol/L, and pH value 3.0. It was found that the conversion kinetics of GA is carried out at the rate constant (kavg.) is 5.7·10-3 s-1, the reaction rate (Δc/Δtavg.) is 6.7·10-7 mol/Ls-1 during 118 s (τ1/2). During the oxidation of GA by Fenton reactions, various intermediate and byproducts are formed, including: hydroxylation products resulting from the attack of hydroxyl radicals on the aromatic ring; cleavage products such as formic acid, oxalic acid, and acetic acid; carbon dioxide and water: complete mineralization of GA to harmless byproducts, indicating the complete oxidation of the organic substrate.Item ACTIVITATEA ANTIFUNGICĂ A NOILOR DERIVAȚI VINIL- TRIAZOLICI CĂTRE FUSARIUM CULMORUM (W.G. SM.) SACC IN VITRO(CEP USM, 2024) Lupaşcu, Lucian; Gavzer, Svetlana; Cristea, Nicolae; Lupaşcu, Galina; Stîngaci, Eugenia; Zveaghinţeva, Marina; Sucman, Natalia; Macaev, FliurObjectives: identification of new compounds with antifungal activity for the phytopathogenic fungus Fusarium culmorum. Methods: the isolation of F. culmorum strains was carried out in aseptic conditions on PDA (Potatoes Dextrose Agar) medium, with the subsequent identification of the species based on macro- and microscopic characteristics. Vinyl-triazole derivatives (D.V.T): EPS-165, MZ-115, MZ-118, EPS-23 were supplemented to the nutrient medium PDA in concentrations of 0,02; 0,01; 0,005; 0,0025; 0,00125%, sterilized by autoclaving. To assess the inhibitory effect of the studied preparations, the method of recording the diameter of the growing colonies was used. Results: the inhibitory effect of the studied preparations was specific depending on the concentration and the strain of the fungus investigated. The preparation MZ-118 offers wider opportunities for use in plant protection measures against the fungus F. culmorum. The factorial analysis demonstrated that in the system F. culmorum x D.V.T. x concentration, the main source of variation in fungal growth is D.V.T concentration. (50.2 ... 64.4%), followed by the isolate factor (24.7 ... 38.9%), which denotes the differential resistance of F. culmorum isolates to the action of the compounds under study.Item STUDIUL CALITĂȚII APEI SUBTERANE DIN TREI LOCALITĂȚI DIN ZONA CENTRU A REPUBLICII MOLDOVA(CEP USM, 2024) Grigoraş, Diana; Mitina, Tatiana; Bondarenco, Nadejda; Bondarenco, Nadejda; Lupaşcu, TeodorGroundwater availability is vital for people, ecosystems, agriculture and industry, but its quality and quantity have been significantly affected by climate change and human activities over the years. In the given study, we aimed to determine quality indices in accordance with the normative act in force, Law on the quality of drinking water No. 182 of 19.12.2019, of groundwater from the following localities: Onițcani and Slobozia-Dușca communes in Criuleni district and Sipoteni village in Calaraș district. The given study confirmed the previously obtained data on the chemical composition of water from artesian wells and wells, and the fact that no sample fully corresponds to the regulations provided for in the drinking water legislation, according to one or more parameters, the most frequent exceeding of the CMA values are established for indicators such as: total hardness, sulfates, nitrates, dry residue, ammonia, etc.Item COMPOZIȚIA CHIMICĂ A EXTRACTULUI DE PROPOLIS(CEP USM, 2024) Grigoras, Carolina; Gonţa, Maria; Ciocârlan, AlexandruPropolis is a natural product with a complex chemical composition, which varies largely by geographical area and plant species visited by bees. Although the propolis collected from the same geographical area has similarities in chemical composition, specific compounds are also attested, due to the local flora. Over the years, numerous studies have been carried out on the chemical composition of propolis, but for the moment there is no common procedure for obtaining and analyzing propolis extracts, which makes it difficult to use the product in the food, cosmetics and pharmaceutical industries. In the present study we aimed to analyze the chemical composition of propolis extracts obtained by maceration with the use of 60%, 70% and 80% ethyl alcohol as solvent, in order to identify the main compounds and analyze the influence of solvent concentration on the extraction of active ingredients. For this purpose, GC-MS and UV-Vis analysis were performed, which confirmed that the predominant constituents are flavanoids with unsubstituted B ring, a characteristic aspect of propolis originating from the temperate zone.