Studying the Sorption of Uranyl Ions from Aqueous Solutions with the Structured 4-Isopropenylphenol-Phenol-Formaldehyde Copolymer

The extraction of uranium salts from aqueous systems was studied under steady-state conditions (at 25 degrees C with the use of a sorbent material based on the 4-isopropenylphenol-phenol-maleic anhydride cooligomer). The effect of different factors (pH of the medium, concentration of uranyl ions (at 25 degrees C), copolymer amount, and exposure time) on the principal sorption process parameters (degree of extraction of uranyl ions and sorption capacity) was revealed. At pH 5-6, the degree of extraction of uranyl ions was established to attain a maximum (similar to 94%) at a sorption capacity of similar to 80 mg/g. At the optimal values of pH (5-6), the dependence of the steady-state sorption capacity on the initial concentration C-0 of uranyl ions was investigated. The steady-state region was observed at a concentration of >200 mg/L and, in this case, the sorption capacity was 101 mg/g. The Freundlich and Langmuir isotherms were plotted, and some hypotheses about possible interactions between uranyl ions and active copolymer moieties were made. The possibility of regenerating the sorbent in the presence of acids and alkalies was also investigated. Maximum desorption of similar to 96.2% was revealed in the presence of mineral acids.