Boosted persulfate activation by hierarchically porous carbonaceous materials: Pivotal role of pore structure and electron-accepting capacity

Abstract

Porous carbonaceous materials (CMs) have been praised as superior candidates in activating persulfate for antibiotic wastewater decontamination. Whereas, as one of the frequently reported nonradical pathways, the formation mechanism of the reactive complexes and their correlation with physicochemical properties of CMs have not been comprehensively unveiled. Herein, a series of carbonaceous materials (CMs) with different specific surface area (SSA) and defect structures were fabricated by using KCl, MgCl2, KHCO3 and K2C2O4 as porogenic agents to activate peroxydisulfate (PDS) for sulfadiazine (SDZ) degradation. Results showed that the total pore volume of CMs exhibited a good linearity with degradation rate, attributing to the combined effect of SSA, defect degree and oxygen-containing functional groups according to multiple regression model. The reactive complexes (CM/PDS*) were proved as the foremost active species for SDZ oxidation via a suite of solid evidences. Compared with that after PS addition, the current direction was reversed after SDZ addition in i-t curves shedding light on the sharp enhanced potential of CM/PDS* and much low potential of SDZ. Furthermore, the inner-sphere CM/PDS* originating from the formation of new covalent bonds between CMs and PDS was inferred due to the poor dependence between electron-donating capacity and SDZ degradation result. The CM/PDS* with considerably higher potential can extract electron from SDZ based on the excellent positive relationship between electron-accepting capacity of CMs and SDZ degradation effect. This study advances the mechanistic comprehension of nonradical PDS activation, and provides a multiple regression model to predict degradation effects of carbon materials.