Fig. 2: Sr²⁺ adsorption performance of ZJU-X99.

a Optical image of ZJU-X99. b Powder X-ray diffraction patterns of ZJU-X99 after soaked in the pH range from 0 to 11 and β radiation. c CO₂ adsorption/desorption isotherms and pore-size distribution profiles (Inset) for ZJU-X99. d Adsorption kinetics curves of ZJU-X99 toward Sr²⁺ (C₀ = 10 mg/L). e Adsorption isotherm curves of Sr²⁺ by ZJU-X99 compared with ZJU-X100. f Effect of Na⁺, K⁺, and Cs⁺ on the adsorption of Sr²⁺ by ZJU-X99 (C₀ = 10 mg/L). g A comparison of Sr²⁺ uptake capacity with reported adsorbents. h Dynamic adsorption and elution curves of ZJU-X99 (C₀ = 8–12 mg/L).