Macroscopic and molecular investigations of immobilization mechanism of uranium on biochar: EXAFS spectroscopy and static batch

A new environmentally friendly and low-cost adsorbent was produced from the camphor tree leaves (BC@CTL) and used to remove U(VI) from waste water via batch capture experiments under varying pH, time, and U(VI) concentration. The resultant biochar was characterized by SEM, BET, zeta-potentials, and FTIR spectroscopy. The capture process was strongly dependent on pH and independent of ionic strength. The capture experimental results indicated that U(VI) was quickly captured to BC@CTL with a maximum capture capacity of 0.41 mmol U(VI) g−1 obtained by Langmuir model fitting. The results of EXAFS analysis revealed that the interaction mechanism of U(VI) on the BC@CTL was primarily controlled by inner-sphere surface complexation. The investigation was meaningful for the “treating wastewater with wastes” strategy implementation, especially biochar can be regarded as a promising candidate for the pre-concentration and immobilization of radionuclides from aqueous solutions in environmental remediation.