In situ generation of H2O2 using MWCNT-Al/O2 system and possible application for glyphosate degradation

Abstract

Hydrogen peroxide (H2O2), as a green oxidant, has been widely applied into advanced oxidation processes (AOPs) for the degradation of toxic organic pollutants. The in situ generation of H2O2 can not only improve the storage and transportation safety of H2O2 but also reduce the capital and operation costs. In the present work, a novel system, i.e., multi-walled carbon nanotube‑aluminum (MWCNT-Al) composite was used to in situ generate H2O2 through micro-electrolysis. The MWCNT-Al composite was characterized and optimized. The accumulation concentration of H2O2 reached 947 mg/L at the initial pH of 9.0, the MWCNT-Al composite dosage of 8 g/L and oxygen gas flow rate of 400 mL/min after 60 min. The in situ generation of H2O2 was achieved by MWCNT-Al/O2 system, mainly owing to the direct contact between Al0 and MWCNT in MWCNT-Al composite, which accelerated the transfer of electrons from Al0 to O2, as well as the excellent electrocatalytic activity of MWCNT toward the two-electron reduction of oxygen. When H2O2 in situ generation technology was used in peroxone process (O3/H2O2 process) to degrade glyphosate in aqueous solution, the removal efficiency of TOC and total phosphorus was 68.35% and 73.27%, respectively. Finally, the possible mechanism of in situ generation of H2O2 in MWCNT-Al/O2 system was temporarily proposed.