Electrochemical-driven Carbocatalysis As Highly Efficient Advanced Oxidation Processes For Simultaneous Removal Of Humic Acid And Cr(Ⅵ)

Electrochemical advanced oxidation processes（EAOPs）represent an efficient and promising strategy for dealing with the ever-growing water pollution.Currently,adding nanoparticles to the traditional two-dimensional electrode system to construct a three-dimensional system,can solve its inherent defects of mass transfer limitation,low free radical utilization rate,low current efficiency and high energy consumption,significantly improving the catalytic performance of the system.Moreover,according to the nature of the pollutants,selecting suitable particle catalysts can improve the removal performance of the target pollutants through the synergy of adsorption/electro-adsorption,catalytic oxidation or electrocoagulation.Meanwhile,carbocatalysis has long and widely been applied in the fields of synthesis and catalysis because of high activity and selectivity.In this work,we combined the advantages of carbocatalysis and EAOPs and for the first time proposed the concept of electrochemical-driven carbocatalysis as highly efficient technology for water remediation,which was simply performed by adding acid/based activated carbon-based particles into the electrochemical system.This novel method shows great potentials for the simultaneous removal of both humic acid（HAC）and Cr（Ⅵ）,in which after 8 hours electrolysis HAC was effectively mineralized with a TOC removal efficiency as high as 90%and Cr（Ⅵ）was completely removed in a short time with a total Cr removal beyond 90%.The presence of carbonaceous particles（e.g.,activated carbon）promoted the electrochemical process:on one side they exerted an important carbocatalytic function with typical AOPs features and on other side they behaved like numerous galvanic cells with quasi-homogeneous catalytic properties,greatly facilitating mass and electron transfers in the system and resulting in a synergistic effect for removal of contaminants.The physicochemical properties of these carbon materials facilitated the simultaneous occurrence of adsorption and carbocatalysis and enabled a fast removal of combined pollutants,where the catalytic performances and mechanisms involved were found to be dependent on the carbon structures（e.g.,surface charge,functional groups and hybridization structure,etc.）.The sp³-hybridization and surface oxygen-containing functional groups of the carbon particles（e.g.,quinone,ketone and carbonyl）were beneficial for the catalytic decomposition of H₂O₂ into·OH,while the sp²-hybridization and the conjugatedπ-system of the carbon were favorable for the generation of O₂·^-.This work details the first insight into electrochemical-driven carbocatalysis and provides a new,green and promising approach for effective water remediation.Importantly,the energy-effective feature and the carbon materials stability showed a promising prospect of this approach with energy consumption much lower than the ever-reported electrochemical AOPs.