STUDY OF THE MECHANISM OF SORPTION OF Cu2+, Co2+, AND Mn2+ IONS ON A MODIFIED NATURAL POLYMER – PECTIN

Abstract

Sorption materials based on apple pectin modified with biologically active organic acids (salicylic, anthranilic, 5-aminosalicylic, nicotinic) capable of effectively extracting Cu2+, Co2+ and Mn2+ ions from aqueous solutions of their salts have been obtained. The regularities of the sorption kinetics of Cu2+, Co2+ and Mn2+ ions by modified pectin samples were studied. An increase in the efficiency of extraction of d-metal ions by modified pectin sorbents compared to the original polysaccharide was revealed. Sorption isotherms of Cu2+, Co2+, Mn2+ ions by modified pectins have been obtained and analyzed for compliance with known theoretical models. Integral kinetic curves have been obtained, and the values of the experimental sorption capacity of biosorbents have been calculated. It was found that the process of sorption of Cu2+, Co2+ and Mn2+ ions on the studied biosorbents proceeds in the diffusion mode. The predominance of the external diffusion nature of the limiting stage of the process of extracting transition metal ions with modified pectins was established. The rate constants of sorption processes are calculated. The values of the apparent activation energy of the sorption process are determined. The thermodynamic parameters of the extraction of Cu2+, Co2+ and Mn2+ ions by pectin sorbents have been calculated. It has been established that the sorption of Cu2+, Co2+, and Mn2+ ions by modified polysaccharide materials is an exothermic process, which can be considered as physical adsorption of metal ions due to solvation and complex formation with the participation of sorbent sorption centers and solvent (water) molecules. The obtained new highly active biosorbents can be recommended as enterosorbents for detoxification of the human body.
 Keywords: sorption, d-metal ions, pectin, modification, kinetic curves, thermodynamic parameters.