Biogenic Cu-based hydroxyapatite nanocomposites for efficient clean of antibiotics: Performance and mechanism

Copper-based catalysts are capable of activating persulfate (PDS) and effectively degrading persistent antibiotic pollutants. In this study, we developed a novel biomineralization regulation strategy to synthesize copperbiomass-hydroxyapatite (Cu-BHAP) composite, aiming to create an environmentally friendly, non-toxic copper-based catalyst for antibiotic degradation as resource recycling. More specifically, biomineralization enhances the adsorption capacity of biomass-hydroxyapatite for copper by increasing its electron transfer rate, and the saturated adsorption capacity for Cu2+ reached 154.3 mg/g. The experimental results showed that the prepared Cu-BHAP sample exhibited superior catalytic activity in the PDS activation process, and 96.19 % removal efficiency of 40 mg/L tetracycline (TC) was achieved within 10 min without pH adjustment (initial pH = 5.8). Meanwhile, density functional theory (DFT) calculation confirmed that the Cu-BHAP catalyst enhanced the electron supply capacity and promoted the activation of PDS. According to scavenger and chemical probe experiments, abundant reactive oxygen species including sulfate radical (SO4-center dot), hydroxyl radical (center dot OH), superoxide radical (O2-center dot), and singlet oxygen (1O2) were responsible for the effective degradation of TC. The potential degradation intermediates of TC were investigated by LC-MS and proved to be less toxic than TC through the ecological structure-activity relationship procedure. Cu-BHAP exhibits a low ion leaching rate, robust performance, and excellent stability. This study provides a simple and green environmental remediation strategy for preparing effective copper-based PDS activators.