Challenges in Liquid-Phase Exfoliation of Non-van der Waals CrS.

Two-dimensional (2D) chromium(III) sulfide has recently attracted increased attention from researchers due to its interesting electronic and magnetic properties and has great potential for application in spintronics and optoelectronics to create sensitive photodetectors. However, the synthesis of 2D CrS crystals is still a challenging task. At present, the mainly used method is vapor deposition, which is a poorly scalable, time-consuming, and expensive process.

A new material built with alternating Cu sulfide and (Al,Mg) hydroxide molecular sheets: hydrothermal synthesis and selected characteristics.

Two-dimensional materials with new physical phenomena are gaining popularity due to their unique properties. In recent years, a new family of layered compounds inspired by the minerals valleriite and tochilinite which are composed of alternating quasi-atomic sheets of transition metal chalcogenides (sulfides and selenides of Fe, Fe-Cu and other metals) and hydroxides of Mg, Al, Fe, Li, ., assembled electrostatic interaction, has arisen as a new synthetic platform for 2D materials.

Specificity of the Thermal Stability and Reactivity of Two-Dimensional Layered Cu-Fe Sulfide-Mg-Based Hydroxide Compounds (Valleriites).

We recently synthesized prospective new materials composed of alternating quasi-atomic sheets of brucite-type hydroxide (Mg, Fe)(OH) and CuFeS sulfide (valleriites). Herein, their thermal behavior important for many potential applications has been studied in inert (Ar) and oxidative (20% O) atmospheres using thermogravimetry (TG) and differential scanning calorimetry (DSC) analyses and characterization with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX). In the Ar media, the processes are determined by the dehydroxylation of the hydroxide layers forming MgO, with the temperature of the major endothermic maximum of the mass loss at 413 °C.

Fractionation of Aspen Wood to Produce Microcrystalline, Microfibrillated and Nanofibrillated Celluloses, Xylan and Ethanollignin.

A new method for extractive-catalytic fractionation of aspen wood to produce microcrystalline (MCC), microfibrillated (MFC), nanofibrilllated (NFC) celluloses, xylan, and ethanollignin is suggested in order to utilize all of the main components of wood biomass. Xylan is obtained with a yield of 10.2 wt.

Sulfation of Birch Wood Microcrystalline Cellulose with Sulfamic Acid Using Ion-Exchange Resins as Catalysts.

Cellulose sulfates are important biologically active substances with a wide range of useful properties. The development of new methods for the production of cellulose sulfates is an urgent task. In this work, we investigated ion-exchange resins as catalysts for the sulfation of cellulose with sulfamic acid.

Food Xanthan Polysaccharide Sulfation Process with Sulfamic Acid.

Xanthan is an important polysaccharide with many beneficial properties. Sulfated xanthan derivatives have anticoagulant and antithrombotic activity. This work proposes a new method for the synthesis of xanthan sulfates using sulfamic acid.

Sulfation of Diethylaminoethyl-Cellulose: QTAIM Topological Analysis and Experimental and DFT Studies of the Properties.

Sulfated cellulose derivatives are biologically active substances with anticoagulant properties. In this study, a new sulfated diethylaminoethyl (DEAE)-cellulose derivative has been obtained. The effect of a solvent on the sulfation process has been investigated.

Towards Understanding the Role of Surface Gas Nanostructures: Effect of Temperature Difference Pretreatment on Wetting and Flotation of Sulfide Minerals and Pb-Zn Ore.

Surface nanobubbles at hydrophobic interfaces now attract much attention in various fields but their role in wetting-related phenomena is still unclear. Herein, we report the effect of a preliminary contact of "hot" solids with cold water previously proposed for generation of surface nanobubbles, on wettability of compact materials and flotation of particulate galena (PbS), sphalerite (ZnS), and Pb-Zn sulfide ore. Atomic force microscopy was applied to visualize the nanobubbles at galena crystals heated in air and contacted with cold water; X-ray photoelectron spectroscopy was used to characterize the surface composition of minerals.

Ultrafine particles derived from mineral processing: A case study of the Pb-Zn sulfide ore with emphasis on lead-bearing colloids.

Although mining and mineral processing industry is a vast source of heavy metal pollutants, the formation and behavior of micrometer- and nanometer-sized particles and their aqueous colloids entered the environment from the technological media has received insufficient attention to date. Here, the yield and characteristics of ultrafine mineral entities produced by routine grinding of the Pb-Zn sulfide ore (Gorevskoe ore deposit, Russia) were studied using laser diffraction analysis (LDA), dynamic light scattering (DLS) and zeta potential measurement, microscopy, X-ray photoelectron spectroscopy, with most attention given to toxic lead species. It was revealed, in particular, that the fraction of particles less that 1 μm in the ground ore typical reaches 0.

On a role of liquid intermediates in nucleation of gold sulfide nanoparticles in aqueous media.

Previously, we found a series of fluid nanoscale intermediates preceding nucleation of gold sulfide in the reaction between aqueous HAuCl4 and sodium sulfide. Here, the effects of temperature, addition of an inert electrolyte and some other factors on characteristics of the "dense liquid" intermediates and the formation of solid nuclei were studied using UV-vis absorption spectroscopy, DLS, zeta-potential measurements, and SAXS. It was revealed, in particular, that the negatively-charged interfaces of the dense liquid species critically impede their fusion into large enough dense droplets in which nucleation can take place.

Direct observation of liquid pre-crystallization intermediates during the reduction of aqueous tetrachloroaurate by sulfide ions.

Phenomena preceding precipitation of gold(i) sulfide in the reaction of aqueous tetrachloroauric acid with sodium sulfide have been studied applying several time-resolved in situ techniques. As can be deduced from UV-vis absorption spectroscopy, soluble species ("pre-nucleation clusters") emerge within several seconds and slightly change with time; the spectra, along with the previous data for the immobilized products, are indicative of disordered matter with Au(I)-S bonding and the gap of about 1.5 eV.

Submicrometer intermediates in the citrate synthesis of gold nanoparticles: new insights into the nucleation and crystal growth mechanisms.

The reduction of tetrachloroaurate by citrate ions in aqueous solutions yielding gold nanoparticles (GNPs) has been studied using in situ tapping mode atomic force microscopy (AFM), UV-vis absorption and dynamic light scattering (DLS) spectroscopies, small-angle X-ray scattering (SAXS) along with ex situ TEM, EDX and XPS. Special attention is given to mesoscale intermediates responsible for the intense coloring of the transient solutions and their role in nucleation and crystal growth. AFM detects liquid droplet-like domains, globules 30-50 nm in diameter arranged in submicrometer aggregates in the gray and blue solutions, and well separated individual particles in the final red sols.

Formation of gold and gold sulfide nanoparticles and mesoscale intermediate structures in the reactions of aqueous HAuCl4 with sulfide and citrate ions.

The effects of the molar ratio of sodium sulfide to chloroauric acid in the range of 0.5 to 5 and the time factor on the formation of the nanoparticles (NPs) of metallic Au, Au(2)S or their mixtures have been studied applying in situ and ex situ techniques (UV-Vis absorption spectroscopy, potentiometry, TEM, SPM, SERS, XPS). The products and intermediates have been compared with those for the reduction of chloroaurate with citrate ions and combinations of citrate and sulfide ions.