The effect of oxygen-containing functional groups on formaldehyde adsorption in solution on carbon surface: A density functional theory study

High-concentration formaldehyde-based wastewater causes a serious hazard to the human body and ecosystem. Electro-Fenton technology can be used for the pre-treatment of high-concentration formaldehyde wastewater, but the uneven distribution of free radicals and formaldehyde affects the degradation efficiency of Electro-Fenton. Oxygen-containing functional groups can enhance the adsorption and enrichment of the pollutants near the cathode, thereby improving the degradation efficiency of Electro-Fenton. In this paper, quantum chemical simulation was adopted to study the effects of different oxygen-containing functional groups on the adsorption of formaldehyde on the carbon surface. The results showed that incorporating oxygen-containing functional groups changed the electronic structure of the carbon surface and affected the interactions between formaldehyde and carbon surface. Only the incorporation of certain oxygen-containing functional groups at the edge of the carbon surface could promote the adsorption of formaldehyde. Edge ether group promoted the basal plane adsorption of formaldehyde on the carbon surface by enhancing dispersion interactions. The edge carboxyl group and edge hydroxyl group influenced the edge adsorption of formaldehyde on carbon surface due to the enhancement of electrostatic interactions. The edge pyrone group promoted the edge adsorption of formaldehyde by influencing the dispersion interactions and electrostatic interactions between formaldehyde and the carbon surface.