Electrochemical processes and systems: application for tutors

The features of redox reactions and the principles of their balancing according to the medium composition are considered. The basic representations about electrochemical processes and systems are outlined. The reactions and principles of chemical sources of electric energy and electrolysis systems functioning are analyzed. A general idea is given about the chemical properties of metals, corrosion resistance in environments of various aggressiveness, and the protection principles are given. Multivariate tasks and exercises for students, and PhD student’s classroom and independent work are offered. For teachers, PhD students and students of universities of specialties "Chemical technologies and engineering", "Biotechnologies and bioengineering", "Oil and gas engineering and technologies".Розглянуто особливості окисно-відновних реакцій і принципи їх балансування залежно від складу середовища. Викладено фундаментальні уявлення про електрохімічні процеси і системи. Проаналізовано перебіг реакцій і принципи функціонування хімічних джерел електричної енергії та систем електролізу. Узагальнено уявлення щодо хімічних властивостей металів, корозійної стійкості у середовищах різної агресивності та наведено принципи організації захисту від руйнування. Запропоновано багатоваріантні завдання та вправи для аудиторної та самостійної роботи студентів і аспірантів. Розраховано на викладачів, аспірантів і студентів вищих навчальних закладів спеціальностей "Хімічні технології та інженерія”, "Біотехнології та біоінженерія", "Нафтогазова інженерія та технології"

Electrochemical processes and systems: application for tutors

The features of redox reactions and the principles of their balancing according to the medium composition are considered. The basic representations about electrochemical processes and systems are outlined. The reactions and principles of chemical sources of electric energy and electrolysis systems functioning are analyzed. A general idea is given about the chemical properties of metals, corrosion resistance in environments of various aggressiveness, and the protection principles are given. Multivariate tasks and exercises for students, and PhD student’s classroom and independent work are offered. For teachers, PhD students and students of universities of specialties "Chemical technologies and engineering", "Biotechnologies and bioengineering", "Oil and gas engineering and technologies".Розглянуто особливості окисно-відновних реакцій і принципи їх балансування залежно від складу середовища. Викладено фундаментальні уявлення про електрохімічні процеси і системи. Проаналізовано перебіг реакцій і принципи функціонування хімічних джерел електричної енергії та систем електролізу. Узагальнено уявлення щодо хімічних властивостей металів, корозійної стійкості у середовищах різної агресивності та наведено принципи організації захисту від руйнування. Запропоновано багатоваріантні завдання та вправи для аудиторної та самостійної роботи студентів і аспірантів. Розраховано на викладачів, аспірантів і студентів вищих навчальних закладів спеціальностей "Хімічні технології та інженерія”, "Біотехнології та біоінженерія", "Нафтогазова інженерія та технології"

Determination of hydroxide and carbonate contents of alkaline electrolytes containing zinc

A method to prevent zinc interference with the titration of OH- and CO3-2 ions in alkaline electrolytes with standard acid is presented. The Ba-EDTA complex was tested and shown to prevent zinc interference with acid-base titrations without introducing other types of interference. Theoretical considerations indicate that this method can be used to prevent interference by other metals

Određivanje titracione kiselosti u belom vinu

The amount of titration acid in must is in the largest number of cases with in the range 5.0-8.0 g/dm3. Wines, as a rule, contain less acids than must, and according to Regulations, titratable acidity is in the range of 4.0-8.0 g/dm3 expressed in tartaric acid, because a part of tartaric acid is deposited in the form of salts (tartar or argol) during alcohol fermentation. For wines that contain less than 4 g/dm3 of titratable acids there arises a suspicion about their origin, that is, that during the preparation some illegal acts were done. Because of that, the aim of this paper is to determine titratable acidity in white wine, using standard methods of determination, which are compared with the results received by potentiometric titration using ion-selective electrode. According to the received results it can be seen that wine titration with indicator gives sufficient reliable values of wine titration acidity. However, as potentiometric titration at pH value 7.00 is more reliable and objective method, the values of titratable acids content in wine, expressed through tartaric acid, are given according to this result. The analysis of differential potentiometric curves shows that these curves can give us an answer to the question of the presence of a larger amount of other nonorganic substances, which have already existed in wine. However, none of the used methods gives absolutely reliable answer what substances are present in analysed samples.Količina titracionih kiselina u širi se, u najvećem broju slučajeva, kreće između 5 i 8 g/dm3. Vina, po pravilu, sadrže nešto manje kiselina nego šira, a prema Pravilniku, titraciona kiselost se kreće između 4,0 i 8,0 g/dm3 izraženo u vinskoj kiselini, jer se deo vinske kiseline istaloži u obliku soli (streša) u toku alkoholne fermentacije. Za vina koja sadrže ispod 4 g/dm3 titracionih kiselina postoji sumnja u njihovo poreklo, tj. da su prilikom njihovog spravljanja vršene nedozvoljene radnje. Zbog toga je cilj rada bio da se izvrši određivanje titracione kiselosti u belom vinu, standardnim metodama određivanja koje su upoređene sa rezultatima dobijenim potenciometrijskom titracijom uz jon-selektivnu elektrodu. Na osnovu dobijenih rezultata uočava se da titracija vina uz indikator daje dovoljno pouzdane vrednosti titracione kiselosti vina. Međutim, pošto je potenciometrijska titracija, pri pH vrednosti 7,00, pouzdanija i objektivnija metoda, vrednosti za sadržaj titracionih kiselina u vinu, izraženih preko vinske kiseline, date su upravo na osnovu ovog rezultata. Analiza diferencijalnih potenciometrijskih krivih, ukazuje da ove krive mogu pružiti odgovor na pitanje o prisustvu veće količine drugih neorganskih supstanci, koje se već nalaze u vinu. Međutim, ni jedna od ispitivanih metoda ne daje dovoljno pouzdan odgovor koje supstance su prisutne u analiziranim uzorcima, već odgovor na ovo pitanje može pružiti jedino metoda jonske hromatografije

Adulteration of Dietary Supplements by the Illegal Addition of Synthetic Drugs: a review

In the last few years, the consumption of dietary supplements, especially those having plants as ingredients, has been increasing due to the common idea that they are natural products posing no risks to human health. In the European Union and the United States, dietary supplements are legally considered as foods/special category of foods, thus are not being submitted to any safety assessment prior to their commercialization. Among the issues that can affect safety, adulteration by the illegal addition of pharmaceutical substances or their analogs is of major concern since unscrupulous producers can falsify these products to provide for quick effects and to increase sales. This review discusses the various classes of synthetic drugs most frequently described as being illegally added to dietary supplements marketed for weight loss, muscle building/sport performance and sexual performance enhancement. Information regarding regulation and consumption is also presented. Finally, several conventional and advanced analytical techniques used to detect and identify different adulterants in dietary supplements and therefore also in foods, with particular emphasis on plant food supplements, are critically described. This review demonstrates that dietary supplement adulteration is an emerging food safety problem and that an effective control by food regulatory authorities is needed to safeguard consumers.This work was supported by European Union (FEDER funds through COMPETE) and Natl. Funds (FCT, Fundação para a Ciência e Tecnologia) through projects EXPL/DTP-SAP/1438/2013 (Safety of plant food supplements: searching for adulterant pharmaceutical drugs and plants) and LAQV UID/QUI/50006/2013.info:eu-repo/semantics/publishedVersio

Studies concerning the anion ex-change resins catalyzed esterification of epichlorohydrin with organic acids

The paper studies the esterification of carboxylic acids with epichlorohydrin over two macroporous strong base anion exchange resins with different polymer matrix. For both resins, the influence of reaction parameters (temperature, catalyst loading, molar ratio) on the reaction rate and the yields of the two isomeric esters were investigated

Total Acid Number Reduction of 2, 6-Naphthalenedicarboxylic Acid Using Subcritical Methanol for Reducing Acidity of Heavy Oil: A Kinetic Study

AbstractNaphthenic acid (NA) found in hydrocarbon deposits is responsible for acidity of petroleum oils. In this study, a model compound of NAs, 2, 6-Naphthalenedicarboxylic acid (NDCA), is used for total acid number (TAN) reduction kinetic analysis. This goal of this paper is to investigate the capability of subcritical methanol (SubC-MeOH) for reducing acidity of NDCA without the addition of any catalyst or additives. The reaction kinetics is also discovered for large scale reactor design. The experiments were carried out in a 25 ml autoclave reactor (China) at temperatures of 180-220oC, a methanol partial pressure (MPP) of 0.1 MPa, reaction times of 0-60 min and a NDCA initial gas phase concentration of 0.03 g/mL. The TAN content of the samples were analyzed using American Society for Testing Materials (ASTM) D 974 techniques. The reaction products were identified and quantified with the help of GC/MS and GC-FID respectively. Experimental results reveal that TAN reduction of NDCA was increasing with increasing reaction temperature and time. Approximately, 52.12% TAN was reduced at a temperature of 220oC, a MPP of 0.1 MPa, and a reaction time of 60 min. Experimental data revealed that TAN removal reaction kinetics followed second order kinetics with an activation energy of 8.24 kcal/mol and a pre-exponential factor of 2.087 fraction-1s-1. Therefore, SubC-MeOH is capable to reduce TAN of NDCA without the addition of any catalyst or additives

Study of Biodiesel Production through Esterification Catalysed by Imidazolium-based Ionic Liquids

Biodiesel is an alternative diesel fuel which is industrially produced from vegetable oils and animal fats, by transesterification reactions. Thus, currently most commercial biodiesel is produced from oils, using alkaline catalysts. On the other hand, conventional mineral acid catalysts like sulfuric acid, are commonly used for catalyzing esterification reactions of fatty acids which also produce biodiesel. However, Ionic Liquids (ILs) offer an alternative solution to classical homogeneous catalysts, because it can be recycled and reused in subsequent runs after recovery steps. An IL is a molten salt consisting of a cation and an anion, with low melting temperature. In this study, a Brønsted acidic IL, 1-butyl-3-methylimidazolium hydrogen sulfate ([BMIM][HSO4]) was used as a catalyst in the esterification of oleic acid with methanol into biodiesel. The effect of different operation parameters such as oleic acid to methanol molar ratio, amount of catalyst, reaction temperature, and reaction time were tested. The optimal conditions for esterification of oleic acid were experimentally determined at 1/10 for oleic acid/methanol molar ratio, 2.5 %wt for the amount of catalyst, a reaction time of 4 h and reaction temperature of 90oC. The Fatty Acid Methyl Esters (FAMEs) content was analyzed using Gas Chromatography.info:eu-repo/semantics/publishedVersio

Medical Chemistry: Theory and laboratory exercises for the first

Manual includes theory and laboratory exercises for the first module of course “Medical Chemistry” for students of medical specialities of universities. It consists of material on se- lected topics: chemical elements and periodic table of the elements, chemical bonding and complex formation, electrolytic dissociation, acidity and acid-base equilibria in solutions, colligative properties of solutions

Chemistry For Iowa Schools, 1965

Chemistry course guide for high school chemistry teachers, designed to assist the teacher in developing his own course so as to best meet the needs of those students planning to attend college. This publication provides resource materials designed to enrich day-to-day teaching