Fig. 4. (a) pH effect on the sorption capacity of ReO4– by SCU-COF-1 (initial concentration of ReO4– = 400 ppm). (b) Removal experiment of ReO4– by SCU-COF-1 with various solid–liquid ratios in 1 M HNO3 solution (initial concentration of ReO4– = 28 ppm or 338 ppm). (c) Removal experiment of ReO4– by SCU-COF-1 with various solid–liquid ratios in 3 M HNO3 solution (initial concentration of ReO4– = 253 ppm). (d) Sorption properties of SCU-COF-1 after being irradiated with different doses of β-irradiation (initial concentration of ReO4– = 2000 ppm). (e) Sorption properties of SCU-COF-1 after being irradiated with different doses of γ-irradiation (initial concentration of ReO4– = 2000 ppm). (f) Reversibility of SCU-COF-1 for removing ReO4– at pH 7 (initial concentration of ReO4– = 28 ppm).
