Biosorption of U(VI) by modified Hottentot Fern: Kinetics and equilibrium studies

Batch experiments were conducted to investigate the biosorption of U(VI) onto Hottentot Fern (Cyclosorus interruptus). The selective adsorption, the adsorption of different sections of Cyclosorus interruptus (CI), and the adsorption of polluted CI compared with that of unpolluted one were studied in detail. The raw CI and the CI modified by CaCl2, MgCl2, MgCl2/H2O2 were investigated for adsorption of U(VI) from aqueous solution. The results indicate that raw CI showed good adsorption selectivity for U(VI), compared with the adsorption of Cu(II), Co(II) and Ni(II). The stem of CI possesses a prominent adsorption capacity compared to the leaf and root of CI, and the unpolluted CI showed its superiority in adsorption capacity than the polluted CI. Adsorption rate was very fast during the first 30 min in the whole adsorption process. The pseudo-second-order kinetics model was proposed for the adsorption of U(VI) and the equilibrium data fitted well to Langmuir adsorption isotherms. The maximum adsorption capacity of R-CI, Ca-CI, Mg-CI and Mg/H2O2-CI is 41.67, 52.63, 62.50 and 71.43 mg g−1 at 20 °C, respectively. •CI was used as precursor for the development of new adsorbents for U(VI) removal.•CI has an excellent selective property to U(VI) adsorption by nature.•The stem of CI has a good adsorption capacity compared to the leaf and root of CI.•The unpolluted CI showed its superiority in adsorption capacity than the polluted CI.•The MgCl2/H2O2 is found to be more effective than CaCl2 and MgCl2 for CI modification.