Promotion of O2 activation by ZIF-8 derived N-rich aluminum-graphite (Al-Gr-NPC) composite for non-radical degradation of antibiotic at neutral pH

Abstract

Recently, the activation of molecular oxygen (O2) by graphite (Gr) supported aluminum (Al) composite for the in-situ generation of H2O2/OH gains increasing attention. However, the limited O2 mass transfer and low catalytic activity of decomposition H2O2 at neutral pH restrict its further application in the wastewater treatment. In this work, a novel N-rich graphite supported aluminum (Al-Gr-NPC) composite was fabricated by introducing the nitrogen-rich porous carbon (NPC) obtained from ZIF-8 derivative as precursor, and by a ball-milling and sintering process. The results showed that the NPC introduction not only improved the physiochemical property of Al-Gr, such as specific surface area, pore structure and hydrophobicity, facilitating the mass transfer of O2, but also made Al-Gr contain plentiful N species, serving as active sites for the two-electron ORR process and catalytic decomposition of H2O2. These excellent performances of Al-Gr-NPC favored the production and utilization of H2O2 by the activation of O2 at neutral pH and air aeration. The carbonization temperature of ZIF-8 determined the type of N species, surface area and the hydrophobicity of NPC. 1O2 was the main oxidant for tetracycline hydrochloride (TC) degradation. 100 % TC degradation and 60.57 % of TOC removal were achieved within 60 min at neutral pH, Al-Gr-NPC dosage of 0.5 g/L and initial TC concentration of 20 mg/L. The toxicity of the final products of TC degradation were much lower than TC by ECOSAR software analysis. Al-Gr-NPC could be used for the removal of antibiotic contaminants from wastewater.