Improving the non-free radical activated peroxymonosulfate capability of sludge biochar through sacrificial template method: Efficacy and mechanism evaluation

Abstract

Improving the non-free radical activation ability of persulfate has great significance for the degradation of persistent contaminant in complex water environments. Here, special nitrogen-doped sludge-based catalysts for peroxymonosulfate (PMS) activation were developed through sacrificial template method by employing polymer surfactant (PS) as template agent. The PS usage and acid etching significantly improved the catalyst’s non-radical activation performance for PMS, the contribution of singlet oxygen (1O2) and electron transfer pathway (ETP) to bisphenol A (BPA) removal could be well matched to 72.31 % and 27.69 % in NCF-1/PMS system, respectively. Such non-radical activation characteristic ensures that NCF-1/PMS systems exhibit super oxidation ability of BPA (Kobs = 0.3714 min−1) and strong anti-interference ability to environmental matrixes via simultaneously enhancing both 1O2 and ETP. The critical roles of graphitic N and as-formed Si-O-C sites in activating PMS were revealed through electrochemical analysis, in-situ characterization technology and theoretical calculations. Density functional theory calculations confirmed that the PS addition and desilication process reduced the adsorption energy of the NCF-1 for PMS, and achieved lower energy barrier to cleave the O–H bond of NCF-1/PMS complex, significantly achieving the surge in the major active species of 1O2. This study provides novel regulatory strategies to modulate the non-radical path for persistent pollutant treatment.