Sustainable and low-carbon removal of emerging contaminants by selective adsorption and phase-transferred electrocatalytic regeneration.

The sustainable management of trace emerging contaminants (ECs) is essential for safeguarding water resources and achieving global carbon-neutrality targets. To address the bottleneck of high energy-consumption and carbon emission caused by the non-selective oxidation of complex organics in conventional advanced oxidation processes (AOPs), we report a sustainable and low-carbon process for ECs removal through a two-step strategy combining selective adsorption and phase-transferred electrocatalytic regeneration using a defect-engineered Fe-N-doped hierarchical porous carbon. Carboxylate-assisted defect modulation constructed hierarchical porosity and enriched pyridinic-N-Fe sites, which not only selectively captured high ionization potentials (IP) contaminants through charge-transfer-driven interactions, but also activated the cathodically generated H2O2 on Fe-N sites to produce •OH to fulfill electro-Fenton (EF) regeneration, restoring over 90% of adsorption capacity without any oxidant addition or pH adjustment. Taking sulfamethoxazole (SMX) as sample EC, the continuous run of the process majority removed SMX with an ultra-low energy consumption (0.034 kWh log-1 m-3) that was only 4.6% and 2.1% of homogeneous EF and electro-oxidation, respectively, while the CO2 emissions reduced by 96.9-99.4% compared with conventional AOPs. Our approach achieves trace ECs purification through a reagent-minimized, cyclic adsorption-regeneration pathway, offering a more energy-efficient and cleaner alternative to conventional oxidation systems and opening new opportunities for sustainable and low-carbon water treatment.