Enhanced electro-peroxymonosulfate activation using a carbon nanotube filter with a functionalized polyelectrolyte

Abstract

An innovative electroactive membrane was designed by polyelectrolyte modification for electro-PMS activation and degradation of refractory organic contaminants in a flow-through filtration model. The pivotal component of this design is a nanohybrid filter, which consists of carbon nanotubes (CNTs) and conductive poly(diallyl dimethylammonium chloride) (PDDA). The study showed that the PDDA–CNT filter could achieve complete CR degradation in 40 min under a PMS concentration of 1.5 mM, an applied voltage of −1 V, and a flow rate of 5 mL min⁻¹ in a continuous-flow configuration. In particular, thanks to the convection mass transmission enhancement, the flow-through scheme exhibited a remarkable 2-times-higher CR degradation efficiency than a traditional batch configuration (44.6%). The excellent organic degradation performance originates from the synergistic affections of electrochemical activity, flow-through design, and abundant active sites. Electron paramagnetic resonance (EPR) techniques and quenching tests verified the singlet oxygen (¹O₂) and direct electron transfer dominated the CR degradation process with electro-PMS activation. Such performance was adaptable over a wide pH window of the solution. The presence of common competitive anions produced inappreciable inhibition to the CR degradation kinetics. This research provides new insights into the rational design of a metal-free PMS activation catalyst toward water decontamination by integrating the state-of-the-art advanced oxidation process, electrochemistry, and membrane separation into a single operating unit.