Nanostructural and Nanochemical Processes in Peloid Sediments Aided with Biogeocenosis

Abstract

Nanostructural and nanochemical processes aided with biogeocenosis in iron-oxide-hydroxide-silicate systems (IOHSS) were studied with physicochemical, colloid-chemical, and biocolloid methods using theoretical concepts of physicochemical and classic mechanics, and geomechanics. As long as general properties of such systems closely match the properties of peloid sediments (PS), the Black Sea and Azov Sea clay-contained PS, peloids and clays were selected as general research materials. Obtained experimental results have shown that nanostructural and nanochemical processes in IOHSS and sediments thereof are controlled by appropriate metabolic processes of microorganisms that are part of the studied systems and sediments. It was established that such microorganisms generally consist of iron-reducing and autotrophic bacteria that produce surface-active substances (surfactants) – amino acids and other organic compounds. Such surfactants take part in physicomechanical hydration self-dispersing processes of micro- and macroparticles in IOHSS and PS up to colloid and nanoparticles. It is shown that at the same time, due to bacterial reactions, Fe³⁺ of micro- and macroparticles turns into Fe²⁺ in the emerging nanoclusters and nanoparticles of iron-containing minerals (hydroxides and silicates). The latter are transformed chemically or microbiologically in unstable layered double hydroxides Fe²⁺· and Fe³⁺ (green rust) under the influence of CO₂ and O₂ of air, mainly of GR(CO₃ ²⁻) type. Respectively, chemical processes between O₂ of air and green rust (GR) lead to their sequential transformation into nanostructures such as: Fe₃O₄ → γ- FeOOH (Lepidigrochitis) → α – FeOOH (Goethite). The last in the contact zones of colloidal, micro-, and macroparticles takes part in the nanochemical processes of creating coagulation–condensation structural bonds in IOHSS that influence upon their rheological and other physical–mechanical characteristics. It is shown that with increasing concentration of solid phase in IOHSS of peloids type, contact links change as follows: coagulation → interphase → solid-state → crystallization. Thus, the flow of IOHSS dispersions with increasing concentration of solid phase and the content of nanoparticles is changed in the following line: thixotropy → dilatance → reopecession → hyperanomaly of viscosity → abnormal plastic flow of solid structures. With the help of theoretical ideas of physicochemical and classical mechanics and geomechanics, an abnormal plastic flow mechanism is established. Examples are available of peloids and individual clays (bentonites and glauconites) application in spa and medical practice as antibacterial compositions and for the correction of a genetically damaged blood coagulation system in hemophilia.