Multi-walled carbon nanotubes facilitated Roxarsone elimination in SR-AOPs by accelerating electron transfer in modified electrolytic manganese residue and forming surface activated-complexes

A novel catalyst (MT/EMR) used for SR-AOPs with high removal efficiency toward roxarsone (ROX) (90.96% within 60 min) was prepared for the first time by ball milling multi-walled carbon nanotubes (MWCNTs) with electrolytic manganese residue (EMR). The incorporation of MWCNTs could improve the adsorption capacity and accelerate the transformation of metals in EMR with partial mass loss to facilitate the PDS activation. Additionally, pH test, quenching experiment and electrochemical test verified a two-electron pathway involving surface activated-complex contributed to the directly ROX oxidization. Benefit from the introduction of MWCNTs, the degradation rate (k(obs)) of catalytic reaction was increased by 10.1 times compared with that of single-EMR. Additionally, the M-O-C (M=Fe or Mn) bonds in MT/EMR making the catalyst more stable than EMR. This work provided a novel and effective strategy to establish waste solid-based catalysts for green preparation and expanded the adsorption-oxidation technology to solve the problem of organoarsenic pollution. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

A novel catalyst (MT/EMR) was successfully prepared for the high removal efficiency of ROX, demonstrating improved adsorption capacity and accelerated metal transformation. By involving a two-electron pathway for direct ROX oxidation, the catalyst showed increased degradation rate compared to single-EMR, with enhanced stability due to M-O-C (M=Fe or Mn) bonds in MT/EMR. This work provides a new and effective strategy for waste solid-based catalysts and expands the application of adsorption-oxidation technology in tackling organoarsenic pollution.