Sensing Properties Of Sno2-Mwcnts Nanocomposites Towards H2

Nanostructures tin (IV) oxides have been synthesized by chemical vapor deposition (CVD) and sol-gel methods and their composites incorporated with multi-wall carbon nanotubes have also been obtained. The characterization of oxidized carbon nanotubes (CNTs) by Raman spectroscopy revealed more defects in CNTs with larger diameters. The tin (IV) oxide nanostructures have been investigated by X-ray diffraction methods, electron spectroscopy and Ramani spectroscopy and results have been showed that SnO2, synthesized by CVD method, characterized by more crystalline structure comparatively to the tin (IV) oxide sample, obtained by sol-gel technology. Sensitivity measurements of SnO2, CNTs and SnO2/CNTs samples towards hydrogen have been carried out. It was found that synthesis method affects not only on physical properties of tin (IV) oxide, but also on the sensing properties. In the case of CNTs samples sensitivity significantly depends on the diameter of carbon nanotubes and oxidation conditions imperceptibly influence on CNTs’ sensing respond. The addition of carbon nanotubes has an ambiguous effect on the sensitivity and the sensing respond strongly depends on CNTs content in the composites

Metaloxide Nanomaterials and Nanocomposites of Ecological Purpose

The features of the properties and creation of nanocomposite metal oxide materials, especially TiO2, ZnO, SnO2, ZrO2, and Fe3O4, and their applications for ecology are considered in the article. It is shown that nanomaterials based on them are very promising for use in the ecological direction, especially as sorbents, photocatalysts, and sensitive layers of gas sensors. The crystallochemical characteristics, surface structure, and surface phenomena that occur when they enter the water and air environment are given for these metal oxides, and it is shown that they play a significant role in obtaining the sorption and catalytic characteristics of these nanomaterials. Particular attention is paid to the dispersion and morphology of metal oxide particles by which their physical and chemical properties can be controlled. Synthesis methods of metal oxide nanomaterials and ways for creating of nanocomposites based on them are characterized, and it is noted that there are many methods for obtaining individual nanoparticles of metal oxides with certain properties. The main task is the correct selection and testing of parameters. The prospects for the production of metal oxide nanocomposites and their application for environmental applications are noted, which will lead to a fundamentally new class of materials and new environmental technologies with their participation

Керамічні мембрани: нові тенденції та перспективи (короткий огляд)

Даний огляд присвячений особливостям формування та застосування керамічних мембран в водоочисних технологіях. У даній роботі на підставі сучасних джерел було розглянуто керамічні мембрани, їх роль у мембранних технологіях; представлено їх структуру, склад та геометричну конфігурацію; визначено перспективи та прогрес, що можна досягти у майбутньому, при розвитку мембран на керамічній основі. Проведено порівняння з полімерними мембранами, в результаті якого визначено, що використання керамічних мембран є більш безпечним для оточуючого середовища та буде сприяти створенню стійких технологій водоочищення, які можуть бути цілком замкнутими. Розглянуто методи синтезу активного шару, модифікування, фабрикування керамічних мембран. Зазначено, що модифікація керамічних мембран наночастинками дозволить маніпулювати їх структурою та властивостями. Використання модифікаторів TiO2, ZnO, Ag тощо дозволить надати керамічним мембранам поліфункціональних властивостей. Незважаючи на широко визнані їх недоліки – крихкість та вартісність, застосування керамічних мембран може швидко окупитись за рахунок більш високих експлуатаційних показників і тривалого терміну служби. До того ж, перспективним направленням у подоланні цих недоліків є фабрикація дешевих та високо функціональних керамічних мембран з використанням нанотехнологій, модифікації їх поверхні проти біообростання та з метою знезараження та створення гібридних мембран. Додатково креслено перспективний напрямок створення керамічних мембран на основі низьковартісної сировини та розробка дешевих анізотропних неорганічних мембран. В цілому зазначається, що мембранні технології при усуненні певних недоліків будуть визнані універсальним та «зеленим» методом очищення стічних вод, який дозволить вирішувати велике коло питань водопідготовки.This review is devoted to the features of the formation and application of ceramic membranes in water treatment technologies. The structure, composition and geometric configuration of ceramic membranes were analyzed. A comparison with polymer membranes was made, as a result of which it was determined that the use of ceramic membranes is safer for the environment and will contribute to the creation of sustainable water treatment technologies, which can be completely closed. Despite their widely recognized shortcomings – fragility and cost, the use of ceramic membranes can pay off quickly due to higher performance and longer service life. Besides, a promising direction in overcoming these shortcomings is the fabrication of cheap and highly functional ceramic membranes using nanotechnology, modification of their surface against biofouling and for disinfection and creation of hybrid membranes. Additionally, the perspective direction of ceramic membranes creation based on low-cost raw materials and the development of cheap anisotropic inorganic membranes is outlined. In general, it is noted that membrane technologies, while eliminating certain shortcomings, will be recognized as a universal and "green" method of wastewater treatment, which will address a wide range of water treatment issues

Characterization of Commercial TiO2 P90 Modified with ZnO by the Impregnation Method

This article is devoted to TiO2/ZnO nanocomposites’ creation by modifying with the commercial TiO2/P90 product using the impregnation method and identifying the effect of the ZnO modifier on its adsorption, structural, photocatalytic, and electrical properties. The synthesized TiO2/ZnO nanocomposites were characterized by XRD, XRF, XPS, and low-temperature nitrogen adsorption-desorption methods. As a result, nanostructured TiO2/ZnO composites with the ZnO content of 2, 5, 10, and 15% were obtained. It was shown that the phase composition of TiO2/P90 does not change during the nanocomposite synthesis. XPS studies of TiO2/ZnO nanocomposites indicated the presence of Ti4+, Zn2+, O2−, and OH states on their surface, which is associated with TiO2, ZnO, and hydroxide ions. The nitrogen adsorption-desorption method showed that the commercial TiO2/P90 sample is nonporous, and all TiO2/ZnO nanocomposites are characterized by almost the same homogeneous mesoporous structure. Experimentally established sorption and photocatalytic properties depend on the specific surface area and electrostatic interaction with dyes. The effect of the ZnO modifier on I-V characteristics of the TiO2/P90 sample was revealed. The obtained experimental data showed that the TiO2/P90 sample contains one type of current carriers, and TiO2/2ZnO and TiO2/5ZnO nanocomposites are characterized by two types of current carriers

Directional Control of the Structural Adsorption Properties of Clays by Magnetite Modification

This article presents the results of the study on the effect of nanomagnetite modification on textural characteristics of clay matrices, adsorption properties, and parameters of the spent sorbents separation. The nitrogen adsorption-desorption method has shown that the obtained magnetic nanocomposite sorbents have large specific surface areas (in 1.2–2 times more) than the initial clays due to the formation of the secondary porous structure on the surface and in macropores of clay matrices. The best adsorption properties with respect to dyes belong to magnetic sorbents with nanomagnetite content of 7 wt.%. The additional modification of the third phase of graphene-like molybdenum disulphide into magnetic sorbents leads to the significant increase in the sorption capacity of both cationic (up to 1100 mg/g) and anionic (up to 1830 mg/g) dyes. The conducted investigations of the total acidity and acid-base sites on the surface of clay, magnetite-modified clay, and molybdenum disulfide-modified magnetic sorbent indicate the significant influence of the Lewis base cites on the adsorption properties of these materials