KINETICS OF MELANOIDIN ADSORPTION FROM AQUEOUS SOLUTIONS WITH ACTIVATED CARBONS

The main reason of melanoidins penetration into water basins is their inflow with industrial waste water. Melanoidins are widely used in industrial sector, thus food industry wastes can lead to ecosystem pollution. To avoid the pollution it is essential to purify industrial waste waters before discharging them into a water basin. The authors studied kinetics and determined kinetic parameters of adsorption using activated carbons which differ in raw material, surface chemistry and porous structure to calculate optimal parameters of adsorption column and modes of waste water continuous cleaning from melanoidins. The research of adsorption kinetics allows to determine the time required to reach adsorption equilibrium «adsorbent - adsorbate» and obtain the parameters necessary for adsorption processes calculation in practice. They determined the rate limiting stage of diffusion and established the porous structure of the activated carbons they studied. The analyses of the experimental curves reflecting the correlation between time and adsorption equilibrium attaining showed that the granules of applied carbon sorbents refer to quasi-homogeneous model. The authors determined that experimental and theoretically calculated kinetic curves are located quite close to each other in the area where the level of adsorption equilibrium attaining has low values. That indicates that limiting external diffusion happens rapidly during the experiment. Further divergence of theoretical and experimental curves can be explained by the role of internal diffusion as the diffusion path inside the grain increases. Judging by the values of the external diffusion mass transfer coefficient during the adsorption of melanoidins from solutions, mass transfer rate depends on the structural characteristics of sorbents.