The insight into the synergistic effect between goethite and birnessite on the degradation of tetracycline

Abstract

The environmental fate of tetracycline (TC) has been documented closely related to goethite (α-FeOOH) or birnessite (δ-MnO2) in soil, while their synergistic effect on TC transformation remains unclear. Herein, a series of δ-MnO2@FeOOH were synthesized to investigate the interaction between α-FeOOH and δ-MnO2 for TC transformation. The results showed that the higher specific surface area and larger amount of surface hydroxyl content were found in δ-MnO2@FeOOH than those of the bulk α-FeOOH and δ-MnO2, enhancing the adsorption capacity for TC. The α-FeOOH introduction was conducive to the electron transfer efficiency and the increase of Mn(III) species, thus, forming more reactive oxygen species (ROSs) for the oxidation of TC. Moreover, the comparative study of the degradation of the common organic pollutants in soli over δ-MnO2@FeOOH indicated the synergistic effect of δ-MnO2 and α-FeOOH showed selectivity in the TC degradation. In addition, 20%δ-MnO2@FeOOH displayed highest removal percentage of 98% for TC (10.0 mg/L) and the removal performance first increased and then decreased as δ-MnO2 loading on the surface of α-FeOOH from 10% to 70%. This study provides a new insight into the transformation of organic pollutant under the interaction between α-FeOOH and δ-MnO2.