Development of biochar supported NiFe2O4 composite for peroxydisulfate (PDS) activation to effectively remove moxifloxacin from wastewater

Abstract

Waste durian peels derived-biochar (DP-BC) supported magnetic nickel ferrite (NiFe2O4) was successfully synthesized at various composite ratios of 5, 10, 15, 20, 25 and 30% between NiFe2O4 NPs and DP-BC. The nanocomposites (DP-BC@NiFe2O4) were then applied to activate peroxydisulfate (PDS) for the removal of moxifloxacin (MFX) from wastewater. The textural, morphology, and structure properties of the DP-BC@NiFe2O4 were systematically characterized. The initial catalytic activity of DP-BC@NiFe2O4 was assessed through the MFX degradation efficiency in the DP-BC@NiFe2O4/PDS systems. The results showed that the pyrolysis temperature of 350 °C gave the highest removal of MFX in the PDS system activated by DP-BC. Besides, loading 15% of NiFe2O4 onto DP-BC gave the highest degradation efficiency of MFX in the DP-BC@NiFe2O4/PDS system with a MFX removal of 88.6% for 90 min reaction. Based on catalyst's property data and quenching tests using different scavengers, the primary mechanisms of MFX degradation by DP-BC@NiFe2O4/PDS system were through both radical and non-radical pathways thanks to effective formation of reactive oxygen species (ROS), consisting of hydroxyl (*OH), sulfate (⁎SO4−), superoxide (⁎O2) and singlet oxygen (1O2) during catalytic reactions. Among ROS, the singlet oxygen (1O2) participated mainly in MFX degradation. The increased formation of ROS in the DP-BC@NiFe2O4/PDS system was due to enhanced PDS activation by the redox reaction a couple of Fe3/Fe2+ and Ni3+/Ni2+ and electron transfer of DP-BC biochar's abundant oxygen-containing surface functional groups. Therefore, it is confirmed that BC@ NiFe2O4 exhibited good catalytic activity in the activation of PDS to effectively remove MFX from wastewater.