Active biochar support nano zero-valent iron for efficient removal of U(VI) from sewage water

The goals of this study were to prepare activated biochar-loaded nano zero-valent iron (A-BC-NZVI) and implemented to remove heavy metal uranium (U(VI)) in sewage water. The A-BC-NZVI composite was successfully synthesized by aqueous phase reduction using biomass longan shell as carbon source under N 2 at 800 °C. The influence of solution pH, A-BC-NZVI dosage, temperature, time and U(VI) concentration on U(VI) remediation via A-BC-NZVI were investigated. The batch sorption experiments reveal that the sorption capacity of U(VI) decreases from pH 7 to 10, and the adsorption kinetic experiments of pseudo-first-order, pseudo-second-order and reduction kinetics were conducted, pseudo-second-order kinetic model was well fitted through the correlation coefficient (R 2 ). At pH 6.0, the maximum U(VI) adsorption amount of Langmuir model was calculated to be 331.13 mg/g, and the thermodynamic constants manifested that U(VI) removal by A-BC-NZVI is an endothermic and spontaneous system. XPS analysis displayed that A-BC-NZVI has two effects on U(VI), including adsorption and reduction. The results proved that A-BC-NZVI is considered highly desirable material on remediation of U(VI) from polluted groundwater. • A-BC-NZVI has been synthesized in one step by using simple aqueous phase reduction. • A-BC-NZVI has both adsorption and reduction of U(VI). • The maximum sorption capacity of U(VI) on A-BC-NZVI was 331.13 mg/g at pH 6.0.