The kinetics of adsorption of ammonium ions under dynamic conditions has been studied. A mathematical model of the process was built. The mass transfer coefficient was calculated depending on the intensity of the change of location. It was established that ion exchange occurs in external and internal diffusion regions. The rate constants of ion exchange for the region of external and internal diffusion were calculated.
This work reveals a method of complex thermal and chemical activation of natural clinoptilolite from Sokyrnytsky deposit. The chemical activation of a mineral was carried out by HCl solutions treatment at various ratios of liquid-to-solid phases. With the use of thermal and infrared (IR) spectroscopic analyses, the adsorption property of a natural and activated clinoptilolite has been examined for water vapor. The ability of complexly activated clinoptilolite to adsorb direct dyes from their aqua solutions has been investigated.
The purpose of this work was to study the process of adsorption of phosphate on natural and synthesized sorbents, such as aluminosilicates. The sorption properties of natural zeolite for phosphate under static and dynamic conditions were investigated. The zeolite on the basis of the coal fly ash of Dobrotvorskaya heat power plant was synthesized and modified. The equilibrium values of adsorption capacity were determined, and the corresponding isotherms were constructed at a temperature of 20° C. The kinetics of adsorption under mechanical mixing conditions was investigated.
Among the large number of well-known and widely used active mineral additives of natural and artificial origin, zeolitic tuffs, an aluminosilicate with microporous framework structure, are of a great interest. Porous active mineral additives also include expanded perlite, which is obtained by thermal treatment of natural perlite – alkaline aluminum silicate glass. The activity of zeolite and perlite is connected to their ability to react with Са(ОН)2 and SO42-. In addition to the composition, their dispersion also has a significant impact on the activity level of mineral additives.
The hydrogen adsorption and desorption isotherms of multiwalled carbon nanotube sample (MWCNT), an iron loaded multiwalled carbon nanotube (Fe_MWCNT), two zeolites (Na_Y_Zeo and NH4_Y_Zeo) and MCM-41 were measured at 77 K and atmospheric pressure by using the volumetric adsorption apparatus. The adsorption data were evaluated by several isotherm equations such as Langmuir, Freundlich, Temkin and Harkins-Jura isotherm models but were best described by the Freundlich isotherm model as it gave the highest correlation.
The statics and kinetics of albumin adsorption on natural zeolite of clinoptilolite structure have been investigated. The basic characteristics of zeolite have been determined. The method of albumin in a solution analysis was given. An isotherm of albumin adsorption was plotted and the Langmuir equation describing this isotherm was given. The presence of an external and pore diffusion adsorption mechanism has been experimentally established during the study of kinetics in a machine with mechanical stirring.
Zeolites were added to polyethersulphone (PES) membranes in order to enhance their capability of attracting creatinine. Zeolite was blended with PES by varying its doping concentration and time, and the mechanical properties of the resulting hollow fibre membranes produced under optimal concentration were characterised. The values of tensile stress, tensile strain and Young’s modulus, as well as the flux and rejection of the membranes were determined.
The adsorption of ammonium ions by natural zeolite and Al2O3 under static conditions has been investigated. The reason for changing the investigated solution pH during adsorption of ammonium ions on Al2O3 has been grounded. A phase diagram of the twocomponent system has been constructed and the composition of the adsorption system in the state of equilibrium has been determined. The thermodynamic calculations of the adsorption system Al2O3–NH4Cl–H2O have been carried out.
Heavy metals in the environment are a source of some concern because of their potential reactivity, toxicity, and mobility in the soil. Zeolites have been used as a adsorbents to prevent potentially toxic metal contamination stemming from mining waste disposal. These materials are characterized by a high cation exchange capacity (CEC) and a predominance of negative charges, favoring their potential utilization in metal cation immobilization. It is widely used in laboratory research and industrial applications. Many physical and chemical processes occur at different interfaces.
Production of Portland cement is one of the most energy intensive among building materials, it is accompanied by significant CO2 emissions: 0,7 to 1 ton per 1 ton of cement, depending on manufacturing technology. Therefore, replacement of Portland cement clinker with active mineral additives of natural or synthetic origin is environmentally and economically viable, while not causing significant adverse changes in the properties of cement binders.