ADSORPTION PURIFICATION OF SUGAR PRODUCTION INTERMEDIATES WITH PALYGORSKITE AND GLAUCONITE

Abstract

The aim of the work is to determine the adsorption properties of natural dispersed minerals of Ukraine, palygorskite and glauconite, in the processes of removing coloring substances in sugar production. The efficiency of adsorption purification of technological solutions of beet sugar production, namely juice II saturation and model molasses solutions with different concentrations of coloring substances in their interaction with natural dispersed minerals of Ukraine, namely palygorskite and glauconite, was studied. The adsorption characteristics of calcium carbonate, which is traditionally used for the purification of intermediate products of sugar production, were also determined. The preparation of natural dispersed minerals was carried out by macerating their aqueous suspensions with a concentration of 5 %. The washed samples of adsorbents were dried and their humidity was determined. The adsorption equilibrium was studied in the temperature range of 20…80 °С. The values of the initial and equilibrium concentrations of coloring substances were determined by spectrophotometric method. The efficiency of dye removal was estimated by the values of specific adsorption of dyes and the decolorization effect of solutions. It was established that the adsorption isotherms of dyes by natural dispersed minerals are described by the Langmuir equation of monomolecular adsorption. The strength of the sorption interaction was estimated by the value of the standard decrease in the free energy of sorption. The best characteristics are inherent in palygorskite, the indicators of separated glauconite, calcium carbonate and natural glauconite are somewhat worse. It was found that with increasing temperature, a decrease in the amount of adsorbed dyes is observed, which indicates a predominantly physical nature of adsorption. Based on the analysis of temperature dependences, the thermodynamic parameters of the purification processes were established. The Gibbs free energy depends little on temperature, and the change in entropy had negative values, which indicates ordering in the system under the action of the adsorbent field. It has been established that the efficiency of extracting dyes by palygorskite and glauconite depends on the pH of the medium and decreases slightly with increasing alkalinity.