Synergistic Catalytic Organic Pollutants Degradation and Cr(VI) Reduction by Carbon Nanotubes through an Electron-Transfer Mechanism without External Energy or Chemical Input

Highly resistant organic pollutants and heavy metals (such as hexavalent chromium (Cr(VI)) usually coexist in industrial wastewater. However, efficient synergistic removal of them is still challenging in practical applications, due to low efficiency and high energy input required for this process. In this study, the metal-free multiwalled carbon nanotubes (MWCNTs) are demonstrated to simultaneously remove bisphenol A (BPA) and Cr(VI) without any external energy or chemical input. In this novel synergistic removal system, the catalytic performance is even higher than those of most of the reported metal-based catalysts in photo/electrocatalytic systems. The catalytic performances are negligibly affected by ions and humid acid, indicating applicability of the catalyst in actual wastewater. In addition, the MWCNT catalyst exhibits good recyclability after thermal treatment under inert atmosphere. Furthermore, the catalytic mechanism of this system has also been comprehensively investigated. This MWCNT-activated synergistic organic pollutants–Cr(VI) elimination system provides a novel and cost-effective strategy of “waste control by waste” for removing multiple industrial contaminants.