Kinetic Model of the Initial Stage of the Process of Colloid Retention by the Pore Space of Sokyrnite

Abstract

The physicochemical phenomena occurring on the surface of sokyrnite grains in complex system "medium grain surface - dispersion medium - surface of suspended particles" have been studied. The framework structure of the sokyrnite structure (rough surface, presence of pores and channels, entrance windows) enables it to work as a "molecular sieve" and to be a highly efficient sorbent-ion exchanger. The porosity of the filter media was determined. Namely: the porosity of the media grains (also called the internal porosity) and the porosity of the intergranular space (media layer). The internal surface area, which is an important quality parameter for sokyrnite as a physical adsorbent, was determined. Several other properties associated with sokyrnite and retained colloidal particles, which affect the strength of the physical adsorption, were investigated. The relationships characterizing the parameters of the zeolite filter media layer were formulated and given. In these studies, the requirements for determining the filter charging time and the optimal technological and design parameters of the filter, according to the operating conditions at a specific water treatment facility, were considered. They determined the need for more detailed research and development of a kinetic model for the initial stage of filtering an aqueous suspension through a filter containing zeolite media. A differential material balance expression for the zeolite filter was formulated. Based on the developed kinetic model, comparative experiments on iron removal from underground natural waters using the above-mentioned filter material were planned and carried out. The mechanism of the distribution of iron ions in the filter space due to the phenomenon of diffusion, in accordance with Fick's first law, is given. The mechanism of iron flake retention by the zeolite media pore space, the consolidation of which occurs during the transition of iron from a divalent to trivalent form, is described. The factors that interfere with autocatalytic processes in iron sediments were described. The dynamics of changes in the concentration of iron in the filtrate after the end of the ion-exchange resource of sokyrnite were studied.