Synthesis and characterization of a new magnetic composite MnFe2O4/clay based on a natural clay obtained from Turkestan deposit

The work is devoted to the development of a new method for the synthesis of magnetic composites based on manganese ferrite on a natural clay, coupling with their physico-chemical characterization. In the study, a natural clay of Kazakhstan obtained from the Turkestan deposit was used for the preparation of magnetic composites. The formation of materials with magnetic properties is an urgent task of our time, due to the needs of various applications of magnetically controlled materials for biomedical systems, electronic devices, catalytic and adsorption processes. The advantage of such materials is the ability to control them using a magnetic field for shaking, recovery, induction heating, among others. In this work, samples were prepared by co-precipitation of manganese and iron salts with 5 mol L-1 NaOH over the Turkestan clay (TC). Materials were characterized by various analyses, such as Fourier-Transform infrared spectroscopy (FTIR), X-ray diffractometric analysis (XRD), and elemental analysis. According to the results of physical and chemical studies of the XRD and thermal analysis, kaolinite is the main mineral in the composition of TC. Magnetic adsorbents MnFe2O4/clay with perfect magnetic separation characteristics were successfully obtained by chemical co-precipitation

Research of the Structure and Physical-Mechanical Properties of Modified Clay

The article presents the properties of natural clay in Uzbekistan. The historical analysis of the use of this natural raw material is presented. Possibilities of changing the properties of clay by introducing synthetic fibers of light industry waste into it are considered. Calculations of the properties of clay with the introduction of various additives and the technology of its processing are given. It has been established that modification of clay with fibrous waste and subsequent heat treatment improves frost resistance, and water resistance of the material, these properties depend on the percentage of fiber content, heat treatment temperature and time of holding the material in the furnace.

The Ceramics Production of the Cis-Ural Srubnaya Culture: A Case Study of the Kurgan Cemetery I Near Tverdilovo Village

The article analyzes the ceramics of the Timber culture, recovered from a kurgan cemetery near the village of Tverdilovo (excavated in 2017 in the Western Orenburg region). Under embankment of kurgan 1, 30 vessels were found in 21 burials, made in a narrow chronological interval. When considering these vessels according to one methodological system, which includes morphological and technical and technological analysis, the peculiarities of the production of pottery were highlighted both for a single group of the population and for the region as a whole. The analysis of the technological traditions of ceramics production from the Tverditovo kurgan cemetery shows that the population that left these ceramics was not homogeneous. There are two different traditions even at the stage of selection of plastic soft raw materials: one of them used silty clay for making dishes, the other applied natural clay. So, it is difficult to explain an isolated case of using sludge and low-grade ferrum clay. Using comparative analysis we can assume that the nearest burial monument according to its ceramics products is the Bogolubovskiy kurgan cemetery where we also can find silty and natural clay and the receipt of molding mass as “clay+ chamotte+ organic materials”. Pottery traditions of the population that left the presented vessels were heterogeneous, which is recorded both in terms of morphological and technological characteristics. A similar picture is typical for other settlement and burial sites in the Orenburg Cis-Urals. The monument was dominated by the pottery traditions of the Timber culture with a slight influence of the Alakul elements.

Correlation between the liquid limit of clay derived by the Vasiliev and Casagrande test methods

The liquid limit is one of the most commonly used index properties of soils. The paper compares liquid limit values determined by the Vasiliev cone penetrometer method and by the Casagrande cup method, based on 45 natural clay samples collected from the Kozloduy Town area (North Bulgaria). An empirical correlation based on these liquid limit results has been derived.

High Sorption and Selective Extraction of Actinides from Aqueous Solutions

The selective elimination of long-lived radioactive actinides from complicated solutions is crucial for pollution management of the environment. Knowledge about the species, structures and interaction mechanism of actinides at solid–water interfaces is helpful to understand and to evaluate physicochemical behavior in the natural environment. In this review, we summarize recent works about the sorption and interaction mechanism of actinides (using U, Np, Pu, Cm and Am as representative actinides) on natural clay minerals and man-made nanomaterials. The species and microstructures of actinides on solid particles were investigated by advanced spectroscopy techniques and computational theoretical calculations. The reduction and solidification of actinides on solid particles is the most effective way to immobilize actinides in the natural environment. The contents of this review may be helpful in evaluating the migration of actinides in near-field nuclear waste repositories and the mobilization properties of radionuclides in the environment.

Experimental Study of the Adsorption of Nitrogen and Phosphorus by Natural Clay Minerals

Nitrogen and phosphorus are commonly recognized as causing eutrophication in aquatic systems, and their transport in subsurface environments has also aroused great public attention. This research presented four natural clay minerals (NCMs) evaluated for their effectiveness of NH4+ and PO43- adsorption from wastewater. All the NCMs were fully characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), BET analysis, and adsorption kinetics and isotherms to better understand the adsorption mechanism-property relationship. The results show that the adsorption efficiency of the four NCMs for phosphate was better than that for ammonia nitrogen. The removal rate of phosphate was higher than 65%, generally in the range of 80%-90%, while the removal rate of ammonia nitrogen was less than 50%. The adsorption kinetic behavior followed the pseudo-second-order kinetic model. The ammonia nitrogen adsorption isotherm was in good agreement with the Freundlich isotherm equilibrium model, and the phosphate adsorption isotherm matched the Langmuir model. Among all the NCMs studied, bentonite (7.13 mg/g) and kaolinite (5.37 mg/g) showed higher adsorption capacities for ammonia nitrogen, while zeolite (0.21 mg/g) and attapulgite (0.17 mg/g) showed higher adsorption capacities for phosphate. This study provides crucial baseline knowledge for the adsorption of nitrogen and phosphate by different kinds of NCMs.