Engineered three-phase interfaces in porous electrodes for efficient in-situ H2O2 generation and synchronous removal of co-contaminants

The co-existence of toxic hexavalent chromium [Cr(VI)] and synthetic organic dyes in dyeing effluents is a prevalent issue, butthe simultaneous removal of these co-contaminants remains a great challenge. Electrocatalytic reduction of oxygen to hydrogen peroxide (H 2 O 2 ) as reductant in the flow-through systems by achieving efficient generation and utilization of active sites is a promising strategy for Cr(VI) reducing detoxification. Herein, a microfluidic flow-through electro-Fenton-like system, incorporating a modified graphite felt (GF) electrode, was developed to enable the simultaneous degradation of Cr(VI) and methyl orange (MO) through in-situ H 2 O 2 generation. This synergistic removal system promoted the degradation of Cr(VI) and MO compared to those in individual contaminant systems (Cr(VI) reduction reached 99.9%, while MO removal efficiency reached 95% simultaneously at a flow rate of 2.5 mL/min、initial pH of 2 and current density 10.19 mA/cm 2 ). Simulation study indicated that the increased number of accessible active sites and its induced nanoscale convection in flow-through system accelerated the nanoscale interfacial mass transfer at PTFE-electrode-solution. Moreover, active species monitoring and the quantum chemical calculation were applied to explore the synergistic mechanism and detailed pathway on the degradation of co-existing contaminants. This work demonstrated the feasibility of simultaneously converting heavy metals and organic dyes, holding great promise for the removal of multiple contaminants in complex wastewater.