Usage of Sorbent-Catalyst to Accelerate the Oxidation of Manganese

The work was supported by National research fund of Ukraine, grant No.144/01.2020.The processes of removal of manganese (II) ions from water using sorbent catalysts, ion exchange materials modified with iron oxides have been studied. It is shown that manganese ions oxidize very slowly in artesian water even when the pH is adjusted to 9.0. Intensive aeration of solutions due to stirring also does not promote oxidation of manganese (II) ions. The degree of manganese extraction due to oxidation is reduced from 20–30 % for solutions with a concentration of manganese ions of 1 and 5 mg/dm3 to 11–15 % for solutions with a concentration of 15 and 30 mg/dm3. A significant increase in the oxidation efficiency of manganese ions was achieved by using magnetite as a sorbent catalyst. The efficiency of water demanganization increases with increasing intensity of water aeration when mixing solutions. It has been established that strongly acid cation exchangers provide efficient extraction of manganese ions from water. At the same time, a high exchange capacity of strong acid cation exchange resin KU-2-8 in acid and salt form was noted. It is shown that the capacity of manganese ions of this cation exchange resin in the Ca2+-form is slightly lower. When using the cation exchange resin KU-2-8 in Ca2+-form to remove manganese ions from the solution already in the first samples, the leakage of manganese ions at the level of 10 mg/dm3 and above was observed. This indicates that this form of ion exchanger is not suitable for deep purification of water from manganese (II) ions. To increase the efficiency of manganese ion extraction from water, increase the duration of the filter cycle, magnetite and magnetite-modified cation exchange resin KU-2-8 were used as a sorbent-catalyst. It was shown that the cation exchange resin modified with magnetite provides the removal of a significant part of manganese ions due to catalytic oxidation on magnetite. The conditions of effective manganese extraction in static and dynamic conditions are determined

Usefulness of habitat suitability models in research of orchid spatial distribution

The subject of this thesis is to summarise information about use of the habitat suitability models with a focus on orchids modelling. Habitat suitability modelling is used to study the relationship between the occurrence of the species and the environmental factors of its habitat. Modelling orchid species is especially useful for modelling of rare and endangered species, it can accurately predict the occurrence of different species under future climatic conditions and in non-native localities. Appearance of mycorrhizal symbiotic fungi is a specific factor affecting distribution of most orchids, but it is very problematic to include it in modelling. Also, there is an uncertainty about an impact of this factor on orchid distribution. Results of different modelling methods are sometimes controversial, this issue is studied, but there are no such studies in orchids modelling. Keywords: Orchids, spatial distribution, models, distribution, predictionPředmětem práce je shrnutí informací o využití modelů vhodnosti stanovišť se zaměřením na specifiku modelování orchidejí. Modelování vhodnosti stanovišť je využíváno k výzkumu vztahů mezi výskytem druhu a environmentálními atributy jeho stanoviště. Modelování výskytu druhů orchideji je užitečné zvláště při modelování vzácných a ohrožených druhů a je schopné přesně předpovídat výskyt druhů i v jiném čase než v současnosti, za jiných klimatických podmínek a na nepůvodních lokalitách pro zájmový druh. Výskyt mykorhizních hub symbiotických pro orchideje je specifickým faktorem pro výskyt většiny orchidejí, avšak jeho zahrnutí do modelování je velmi problematické. Rovněž výsledky výzkumu tohoto faktoru na distribuci orchidejí si někdy navzájem protiřečí. Výsledky různých modelovacích metod se liší, tato problematika se zkoumá, avšak chybí její výzkum na orchidejích. Klíčová slova: Orchideje, prostorová distribuce, modely, rozšíření, předpověďKatedra ekologieDepartment of EcologyFaculty of SciencePřírodovědecká fakult

A review of global land cover maps in terms of their potential use for habitat suitability modelling

Recently, there has been a significant increase in number of land cover maps available to researchers and they are now more commonly used. The broad variety requires some system for determining the differences between maps and for estimating their applicability for specific research purposes. We focused on comparing land cover maps from the point of view of how the land cover categories used characterize potentially suitable habitats for species. This comparison includes only freely available global land cover projects with resolutions from 1 km to 10 m. The criteria chosen were temporal and spatial resolution, number of classes and map precision. To demonstrate the differences, two areas of different sizes were always chosen. Our results reveal that maps can significantly vary in their estimates of different types of land cover, even at the same spatial resolution. Results also revealed that one type of vegetation in this area is poorly recorded in all land cover maps. Copernicus CGLS-LC100 and ESA CCI-LC maps appear to be the most suitable for evaluating potentially suitable habitats

Electrodeposition of polyfunctional Ni coatings from deep eutectic solvent based on choline chloride and lactic acid

The process of electrodeposition of nickel coatings from electrolytes based on a deep eutectic solvent (DES) mixture of choline chloride and lactic acid with a molar ratio of 1:3 was studied. The physicochemical properties and characteristics of DES, namely, con­ductivity, FT-IR and NMR analysis were determined. FT-IR results confirmed that H-bonds occurring between two components in DES were the main force leading to the eutectic formation. Electrochemical techniques were used to characterize the deposition process and scanning electron microscopy was used to study the deposit morphology. Based on polarization measurements, it has been found that at NiCl2·6H2O content of 1.14 M and a temperature of 75 °C, the limiting current density of nickel electrodeposition was near 2 A dm-2. The polarization of the cathodic nickel deposition varied within -0.63 to 1.1 V at current density of 0.25 A dm-2 It has been shown that an increase of water content in the electrolyte does not significantly affect the current efficiency of the nickel electrodeposition process, which was in a range 85-93 %. However, the increase in water content contributes to the increase of heterogeneity and crystal grains size distribution of galvanic deposits. The established values of the Wagner number indicate the predominance of the primary current density distribution in the process of electrodeposition of nickel coatings. Galvanic coatings possess a highly developed nanostructured surface, exhibit increased capillary properties, and can be used as electrode materials for the process of electrolysis of water

Influence of polarization curve slope on the accuracy of local copper electrodeposition from sulphate electrolyte

Local electrochemical deposition is an emerging technique, used in the field of additive manufacturing. The advantage of electrochemical additive manufacturing lies in the utilization of room temperature electrolyte and permits to manufacture microscale objects with high precision. The increase in deposition current increases the deposition area, so measures are to be taken to focus the electric field. This work describes the influence of polarization curve slope on the accuracy of local deposition, both experimentally and by computer modelling. The copper was deposited using rotating anode on the surface of stainless steel from sulphate electrolyte. The influence of electrolyte composition on the accuracy of deposition was investigated. The profile of deposited parts was analyzed by profilometry and microscopy. The increased amount of sulfuric acid and presence of the additive in the electrolyte was shown to increase the accuracy of deposition by changing the slope of cathodic polarization curve from 320 to 1100 mA V–1cm–2)

Sorbent-Catalyst for Acceleration of The Iron Oxidation Process

In this work, the process of water deironing by using magnetite as a catalyst to accelerate the oxidation of iron ions in an aqueous medium was investigated. It was shown that the efficiency of iron ion extraction depends on the solution concentration, sorbent dose and contact time. In all cases, the use of magnetite accelerated the process of extraction of iron by more than an order of magnitude in comparison with similar experiments on the oxidation of iron without the addition of a catalyst. At the pH values greater than 6, the use of magnetite as a catalyst contributes to the deep purification of water from iron ions

Photoelectrochemical characterization and photocatalytic properties of mesoporous TiO

Optically transparent, crack-free mesoporous titania and zirconia-doped titania thin film photocatalysts were fabricated by sol-gel technique, using nonionic amphiphilic block copolymer Pluronic P123 as template. The structural and optical properties of these films were characterized using SEM, low-angle XRD, and UV/Vis spectroscopy, hexane adsorption investigation. Band gap energy and the position of flatband potentials were estimated by photoelectrochemical measurements. Enhancing of photocatalytic activity of zirconia-doped films relative to pure TiO2 originates from an anodic shift of the valence band edge potential. Catalytic activity of mesoporous TiO2 and TiO2/ZrO2 (5–50% of ZrO2) films in the processes of CrVI to CrIII photoreduction and 2,4-dinitroaniline photooxidation correlates with crystalline size and growth with increasing of specific surface area of the samples

Коррозионный синтез сульфидов никеля – перспективных электродных материалов возобновляемых источников электроэнергии

На основе анализа литературных данных установлено, что сульфиды никеля являются эффективными электрокатализаторами и могут быть использованы в качестве электродных материалов первичных, а также возобновляемых источников тока – топливных элементов. В ходе экспериментальных исследований установлено, что синтезированный, путем коррозионного растворения, никель-сульфидный слой обладает повышенной каталитической активностью по отношению к процессу электровостановления кислорода

Влияние электроосмотических явлений на время переходных процессов в амперометрических газовых сенсорах

Стаття присвячена 100-річчю з дня народження видатного вченого-електрохіміка,член-кореспондента АН УРСР Л.І. Антропова і продовжує цикл досліджень перехідних процесів у амперометричних сенсорах. Виявлено причини розбіжностей у тривалості перехідних процесів, які при вимірюваннях, розмежованих перервою від кількох хвилин до кількох годин, не дають змоги за величинами часу виходу струмового сигналу на 10 і 50 % від його стаціонарного значення оцінити очікуване значення достовірного сигналу сенсора ще до його стабілізації. Показано, що перебіг електродної реакції викликає тимчасове зростання струмоутворювальної поверхні робочого електрода сенсора, яке нівелюється через кілька хвилин після припинення подачі визначуваного компонента в аналізовану газову суміш. Причиною цього явища є осмотичне накопичення води в зоні струмоутворювальної реакції внаслідок абсорбції її парів із повітря та дифузії з глибини розчину електроліту, що потовщує плівку розчину й спотворює форму його меніска. Протягом часу існування меніска, форма якого спотворена попередньою генерацією струмового сигналу, тривалість перехідного процесу скорочується внаслідок швидшого зарядження поляризаційної ємності робочого електрода більшим за силою струмовим сигналом.The work is dedicated to the 100th anniversary of the birth of great scientist-electrochemist, corresponding member of USSR SA L.I. Antropov and continues series of studies of transients processes in amperometric sensors. Reasons of differences in the duration of transient processes in the measurements, differentiated break from several minutes to several hours, allowing time for the values of the output current signal by 10 and 50 % of its stationary value to estimate the expected value of reliable sensor signal prior to its stabilization were revealed. It was shown that the course of the electrode reaction causes a temporary increase in current-generating surface of the working electrode sensor, which leveled in a few minutes after stop the flow of detectable component in the sample gas mixture. The reason for this phenomenon is the osmotic accumulation of water in the current-generating reaction area due to absorption of vapor from the air and from the depth of diffusion of the electrolyte solution, which thickens the solution film and distorts the shape of the meniscus. During the existence of the meniscus, which shape is distorted by the previous generation current signal, transition time is reduced due to faster charging of working electrode polarization capacitance by greater than the current signal.Статья посвящена 100-летию со дня рождения выдающегося ученого-электрохимика, член-корреспондента АН УССР Л.И. Антропова и продолжает цикл исследований переходных процессов в амперометрических сенсорах. Выявленные причины расхождений в длительности переходных процессов, которые при измерениях, разделенных перерывом от нескольких минут до нескольких часов, не позволяют по величинам времени выхода токового сигнала на 10 и 50 % от его стационарного значения оценить ожидаемое значение достоверного сигнала сенсора еще до стабилизации. Показано, что протекание электродной реакции вызывает временный рост токообразующей поверхности рабочего электрода сенсора, который нивелируется через несколько минут после прекращения подачи определяемого компонента в рассматриваемую газовую смесь. Причиной этого является осмотическое накопление воды в зоне токообразующей реакции вследствие абсорбции ее паров из воздуха и диффузии из глубины раствора электролита, утолщающих пленку раствора и искажающих форму его мениска. За время существования мениска, форма которого искажена предварительной генерацией токового сигнала, длительность переходного процесса сокращается вследствие более быстрого заряда поляризационной емкости рабочего электрода большим по силе токовым сигналом