Investigation of the surface properties of quartz-based dispersed materials

Abstract

Researched quartz disperses materials (Ukraine): mineral - quartzite of the Ovruch deposit and quartz sand of the Novovodolazsky deposit and products of processing of quartz minerals - dinas and marshalite. The mineral composition, surface morphology, dispersion and specific surface area were experimentally studied. The structure of the hydroxyl-hydrate surface layer was studied by thermogravimetric (TG) analysis and differential thermal analysis (DTA). The number and acid-base characteristics of surfaces active centers were investigated by the methods of pK-metric and pH-metric. It is established that the mechanisms of physical and chemical adsorption of water molecules on the surface of all quartz dispersed materials are identical and do not depend on the mineral nature of impurities. It is shown that the thickness of the surface hydroxyl-hydrate layer of quartz dispersed materials is determined by the amount of chemically adsorbed water, i.e. the thickness of the hydroxyl layer and depends on the nature of the associated minerals. It is established that the acid-base surface characteristic of quartz materials significantly depends on the chemical nature of the accompanying minerals and does not depend on the thickness of the surface hydroxyl-hydrate layer.

Rice husk-derived nano-SiO2assembled on reduced graphene oxide distributed on conductive flexible polyaniline frameworks towards high-performance lithium-ion batteries

“…The loosely bound or physically adsorbed water molecules can be attributed to the initial weight loss of approximately 20% (up to 200 °C). 32 Another possibility was the loss of C O species and followed by gradual decomposition of carbon dioxide up to 650 °C and degradation of the polymer backbone with residual carbon, which would constitute the second step degradation. 29 Thus, the calculated SiO 2 content in the SiO 2 @rGO and PANI-SiO 2 @rGO composite samples were 36.5 weight% and 5.68 weight%, respectively.…”

Potentiometric (pH-Metric) Methods of Studying Acid-Base Properties on the Surface of Dispersed Materials

“…It has been proven that during firing or during mechanical processing (grinding) the number and acid-base characteristics of active centers on the surface of dispersed materials change [5]. When water is adsorbed on the solid surface of any structure, a hydroxylhydrate layer is formed, which is characterized by a wide range of active adsorption centers (ACA) [6][7][8], whose acid-alkaline properties are of great scientific interest, but not sufficiently studied.…”

“…The nature and acid-base properties of ACA have been most thoroughly studied for dispersed crystalline materials of an inorganic nature, which is related to the more or less known chemical composition and crystal structure [6][7][8]. The complexity of studying the surface of dispersed inorganic materials of an amorphous structure or materials of organic origin is caused by the need to identify a surface with a complex chemical structure and unstable composition [18,19].…”

Acid-Alkaline Surface Properties of Powders: Potentiometric Research Methods

“…The regularities of interactions on the surface of the phase separation in any case can be described as reactions between acids and alkalis by Brønsted (protic reactions) or Lewis (aprotic reactions). It is believed that a hydroxyl-hydrate layer is formed on the surface of dispersed materials, which consists of chemically bound water molecules, which form the first lower hydroxyl layer of OH-groups (Brønsted centers) and subsequent hydrate layers of water molecules that are more distant from the solid surface, connected with the hydroxyl layer due to hydrogen and other physicochemical bonds [1][2][3].…”