Synergistic removal of chromium(VI) and tetracycline by porous carbon sponges embedded with MoS2: Performance and radical mechanism of piezoelectric catalysis

The presence of hexavalent chromium(VI) Cr(VI) and antibiotics in the environment can lead to the formation of combined pollutants that are harmful to ecosystems. To address this problem, we synthesized MoS2 embedded in the porous super-hydrophilic polyurethane (PU) sponge and used weak water flow to drive the piezoelectric catalytic synergistic degradation of Cr(VI) and tetracycline (TC). In this study, the piezoelectric properties of MoS2/PU were confirmed via piezoresponse force microscopy (PFM) and COMSOL multiphysics calculations. Additionally, dynamics experiments, quenching experiments, electron paramagnetic resonance (EPR) spectroscopy, three-dimensional fluorescence excitation-emission matrix (3D-EEM) spectroscopy, and free radical generation rate analysis were conducted to explore the removal performance and mechanisms of MoS2/PU on the TC-Cr(VI) system. The results indicated that the coexistence of the two pollutants promotes the transfer of charge in MoS2/PU, further combined with O2 to produce H2O2 and continued to produce center dot OH. The removal rates of TC and Cr(VI) in the TC-Cr (VI) mixed system at 30 min were 97 % and 94 %, respectively, which were 1.45 and 1.46 times those of the single TC and single Cr(VI) systems, respectively. Finally, potentially vulnerable sites of TC were calculated and analyzed according to density functional theory (DFT). Our results provide a new strategy for improving the degradation efficiency of antibiotics and Cr(VI) metals.