Floating sandwich-type electro-Fenton: A feasible process to remove micro-pollutants through adsorption enrichment...

To improve the removal efficiency of low-concentration organic pollutants and enhance the oxidation efficiency of electro-Fenton (EF) process, a floating sandwich-type EF system (N/(A)/D-EF) without aeration was constructed for the first time. This EF system electro-synthesized H₂O₂ through the floating natural air diffusion electrode (NADE) without aeration, and regenerated Fe(II) effectively by the activated carbon fiber (ACF) interlayer, which significantly enhanced the process oxidation capacity since its ^•OH yield was 8.7 times that of the conventional EF system. In addition, the ACF interlayer could adsorb and enrich micro-pollutants and the generated ^•OH directly oxidize the pollutants adsorbed on the ACF, which enabled regeneration of ACF and maintained removal stability in 20 consecutive experiments. The removal rate constant (k) of carbamazepine by N/(A)/D-EF process was 7.6 times and 2.1 times higher than that of conventional EF and ACF adsorption process, respectively. This process could efficiently remove mixed low-concentration organic pollutants (0.1 mg L^-1) in domestic sewage and lake water with rate constant 1.6-7.1 times that of the conventional EF process but lower energy consumption. Meanwhile, the N/(A)/D-EF process had a wider application range of sewage pH and conductivity, which was a promising process for removing low-concentration pollutants in wastewater.