SORPTION OF NON-FERROUS METAL CATIONS ON SPHEROGRANULATED AMOPTHOUS TITANIUM HYDROXIDE

The sorption properties of amorphous titanium hydroxide ion-exchanger (ATH) toward non-ferrous metal cations are investigated. The sol-gel synthesis of ATH is based on the method of limited hydrolysis of ammonium titanyl sulfate (NH4)2TiO(SO4)2·H2O (ATS) without the usage of organometalic compounds. The presence of ammonium ion in sol prevents the polymerization of gels, which has a positive impact on porosity of the obtained compounds and, consequently, on ion-exchanging characteristics. The sorption isotherms for five divalent metal ions including Pb2+, Cd2+, Cu2+, Zn2+, and Ni2+ are built. The isotherms are best described with the Freundlich model in the case of sorption of cadmium and lead cations, and with the Langmuir and Freundlich models in the case of sorption of zinc, copper and nickel cations. The sorption kinetics of these metal ions on the ATH is limited by internal diffusion. The selectivity order of the metal ions on TiP1 is determined as follows: Pb2+ > Co2+ > Cu2+ > Ni2+ > Cd2+ > Zn2+. Additional sorption studies are carried on industrial water containing a mixture of divalent and hardness cations. The quality of water after the sorption on the ATH sorbent reaches the EU recommendations for drinking waters for most of the metal ions concentrations. In the case of wastewater treatment in tannery industry, the sorption of chrome cations on the ATH exceeds 99% for all types of wastewater and the remaining concentration of chrome ions (III, VI) in the solution is lower than maximum concentration limit

ION-EXCHANGE MATERIALS BASED ON HYDROXOOXOTITANE FOR WASTE WATER PURIFICATION

The present investigation deals with preparation of a stable titanium (IV) colloid solution from ammonium oxysulfotitanate (NH4)2TiO(SO4)2∙H2O and oxysulfotitanate TiOSO4∙ H2O solutions. The colloid precursor was used in the synthesis of spherical TiO2 particles with ion-exchange properties. A relationship between the nature of the initial solution, the number of terminal and bridging OH groups in resulting sol, and the sorption properties of hydroxooxotitane prepared by sol–gel method has been established. Studies of the exchange behavior of different cations have confirmed the dominant role of bridged OH- groups

Synthesis of Sorption Materials from Low Grade Titanium Raw Materials

In this paper, a universal technology is proposed for processing low-titanium mineral raw material—apatite-nepheline ore waste, including its treatment with sulfuric or hydrochloric acid in a two-stage mode with a sequential increase in the concentration. This technique allowed us to remove nepheline and apatite in the first stage and achieve a titanium mineral content of TiO2 of more than 30%; in the second stage, we were able to convert the titanium into its precursors—titanyl sulfate monohydrate TiOSO4·H2O and a hybrid rutile-silica composition. The key stage in the sorbent synthesis is the reaction of the precursor with a phosphoric acid solution. The preferred sequence of operations begins with the mechanical activation of the precursor, causing morphological changes in it, and subsequent treatment with phosphoric acid at different concentrations under atmospheric conditions and in an autoclave, accompanied by phase transformations. Conditions for the chemical reactions which regulated the composition and structure of the final product and, accordingly, its sorption activity were found. With the help of XFA, the phase compositions of the sorbents were identified, including the individual crystalline phase α-TiP obtained from TS or the crystalline phase αTi(HPO4)2∙H2O, which is in an amorphous silica matrix obtained from a rutile–silica composition

CRYSTALLIZATION OF THE FRAME-STRUCTURED TITANOSILICATE IN A HIGHLY ALKALINE MEDIUM

The conditions for the crystallization of the frame-structured titanosilicate with the use of a solution of Ti4+ sulfate with the addition of alkali in the form of liquid glass and sodium alkali to a pH of 12.5-13.5 have been studied. The optimum molar ratio of TiO2: SiO2 is 1: 4.5. To increase hydrolysis stability, partial reduction of initial solution has been fulfilled by electrochemical method with Ti4+ conversion to Ti3+ (content of Ti2O3 in the solution after reduction is 30–45 g/l). This expedient allows avoiding premature generation of a titanium amorphous phase and directing the process to creation of crystalline precipitate in a form of two structural modifications: trigonal (Na4(TiO)4(SiO4)3·6H2O) and cubic (Na3H(TiO)4(SiO4)3·4H2O); the precipitate crystallinity degree is 90–95%. Both structures are similar to the structure of the ivanyukite mineral. Crystallization proceeds under significant oversaturation system by alkaline components. Determined have been optimal conditions for titanium - siliceous precursor sol-gel obtaining and consequent hydrothermal transformation of the obtained gel to crystalline phase. It has been shown that the pore system (total volume of pores) of crystalline ivanyukite particles is approximately 1.5 times larger than that of X-ray amorphous samples and that it is mainly represented by mesopores of medium size, which are characterized by the most activity in sorption processes. Natrium and potassium ions situated in the ivanyukite frame space along with water provide high exchange velocity of cations absorption in sorption processes due to minimal diffusive obstacles. The reported preliminary data on sorption allow to describe the frame-structured crystalline alkaline titanosilicates as effective sorbents of one or two charge cations, as shown by the example of the sorption of strontium, caesium and non-ferrous metals

Mineral Layer Fillers for the Production of Functional Materials

An original method based on the use of technogenic waste from the processing of mineral-layered materials, in particular phlogopite for obtaining highly efficient functional compositions of the “mica-TiO2”, has been developed. The composition core is a nanosized mica flake coated with mesoporous titanium dioxide of an anatase or rutile structure. Energy-saving and environmentally friendly technological methods are based on the splitting of the mica followed by heterogeneous electrohydrolysis of a mixture of titanium (IV) sulfate solution and flake particles. No destruction of the mica surface, which provided the obtained uniform coatings, has been observed. Such coatings are used in photocatalysis processes and possess a self-cleaning capability. Core–shell compositions are more economically attractive compared with titanium dioxide, in particular TiO2 grade P25 (Degusse). The core of the transparent flake and the shell of the rutile titanium dioxide endows the final product with a pearlescent optical effect. This type of material is widely used in the manufacturing of paints and varnishes, printing inks, cosmetics, etc. The use of technogenic waste could significantly reduce the cost of the final product, which would ensure its widespread use in various industries

Bacteria as agents of biocontrol of phytopathogens after laser stimulation and of their metabolites’ impact on plants

The problem of increasing activity of phytopathogen antagonist bacteria under the influence of laser irradiation is considered in this paper. Studies on Bacillus subtilis and Pseudomonas fluorescens from various plant protection products have shown that use of laser irradiation leads to an increase in the number of cells in bacterial suspensions. This indicator increased to a maximum of two times at effective exposures in comparison with the non-irradiated variants. That was justification for the need to study the nature of the impact of excessive content of metabolites in the substrate synthesized by such a quantity of bacteria from biological products, which is 2 or more times higher than the number of cells in the standard solutions. With a twofold and fourfold increase in the concentration of metabolites of the studied bacteria compared to their standard content in the medium, the photosynthetic activity of cucumber microplants increased by more than 32%. This suggests that laser stimulation of bacteria – agents of biocontrol of diseases does not adversely affect the functional state of plants

Impact of coherent light on interaction of fungi and bacteria cells cultivated

This article considers impact of coherent red quasi-monochromatic light on interaction of colonies of the Pseudomonas syringae bacteria and the Fusarium macroceras fungus in an in vitro culture. A helium-neon laser and a heat source with a system of light filters and aperture diaphragms were used for irradiation. Two light fluxes were obtained with energy parameters close in magnitude, but significantly different in spatio-temporal coherence. Light with a high statistical ordering stimulated growth of both colonies. Irradiation from the same spectral range and intensity, but with low spatial coherence, increased the functional activity of only small bacteria cells. As a result, there was a suppression of larger fungal cells development that were interacting with them. Therefore, it was the statistical (coherent) properties of light that affected the change in the equilibrium of microorganisms in an artificial biocenosis. This approach can be used in practice for increasing the activity of bacteria antagonists of pathogenic fungi and the non-chemical disease protection of plants

Titanite-Containing Mineral Compositions and Their Chemical Treatment with Preparation of Functional Materials

The waste of apatite-nepheline ore processing was chosen as the material of study for the present investigation. The chemical and phase compositions have been analyzed and the route of the new technology has been developed. Treatment of the waste with diluted hydrochloric acid enables to separate apatite, nepheline, titano-magnetite minerals from titanite (CaSiTiO5). The obtained titanite concentrate contains 30–32% of titanium dioxide. Interaction of titanite with hydrochloric acid under heating and stirring conditions results in calcium leaching. The titanite decomposition is accompanied by titanium and silica oxides precipitation. The resulting solid has been used as a precursor for the synthesis of functional materials. Mechanochemical activation of the precursor provides the structural and morphological disorder of the initial particles. Thermodynamic stability of activated particles is achieved by chemisorption or roasting

Selection of Diagnostically Significant Regions of the SLC26A4 Gene Involved in Hearing Loss

Screening pathogenic variants in the SLC26A4 gene is an important part of molecular genetic testing for hearing loss (HL) since they are one of the common causes of hereditary HL in many populations. However, a large size of the SLC26A4 gene (20 coding exons) predetermines the difficulties of its complete mutational analysis, especially in large samples of patients. In addition, the regional or ethno-specific prevalence of SLC26A4 pathogenic variants has not yet been fully elucidated, except variants c.919-2A>G and c.2168A>G (p.His723Arg), which have been proven to be most common in Asian populations. We explored the distribution of currently known pathogenic and likely pathogenic (PLP) variants across the SLC26A4 gene sequence presented in the Deafness Variation Database for the selection of potential diagnostically important parts of this gene. As a result of this bioinformatic analysis, we found that molecular testing ten SLC26A4 exons (4, 6, 10, 11, 13–17 and 19) with flanking intronic regions can provide a diagnostic rate of 61.9% for all PLP variants in the SLC26A4 gene. The primary sequencing of these SLC26A4 regions may be applied as an initial effective diagnostic testing in samples of patients of unknown ethnicity or as a subsequent step after the targeted testing of already-known ethno- or region-specific pathogenic SLC26A4 variants