Activation of persulfates by natural magnetic pyrrhotite for water disinfection: Efficiency, mechanisms, and stability. (1st April 2017)

• Record Type: Journal Article
• Authors: Xia, Dehua; Li, Yan; Huang, Guocheng; Yin, Ran; An, Taicheng; Li, Guiying; Zhao, Huijun; Lu, Anhuai; Wong, Po Keung
• Is Part Of: Water research. Volume 112(2017)
• Page Start: 236
• Page End: 247
• Publication Date: 2017-04-01
• Subjects: Natural pyrrhotite -- Persulfate -- Sulfate radical -- Water disinfection -- Heterogeneous catalysis; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2017.01.052
• Languages: English
• ISSNs: 0043-1354

Abstract

Abstract: This study introduces natural occurring magnetic pyrrhotite (NP) as an environmentally friendly, easy available, and cost-effective alternative catalyst to activate persulfate (PS) of controlling microbial water contaminants. The E. coli K-12 inactivation kinetics observed in batch experiments was well described with first-order reaction. The optimum inactivation rate ( k = 0.47 log/min) attained at a NP dose of 1 g/L and a PS dose of 1 mM, corresponding to total inactivation of 7 log10 cfu/mL cells within 15 min. Measured k increased > 2-fold when temperature increased from 20 to 50 °C; and > 4-fold when pH decreased from 9 to 3. Aerobic conditions were more beneficial to cell inactivation than anaerobic conditions due to more reactive oxygen species (ROS) generated. ROS responsible for the inactivation were identified to be SO4 − > OH > H2 O2 based on a positive scavenging test and in situ ROS determination. In situ characterization suggested that PS effectively bind to NP surface was likely to form charge transfer complex (≡Fe(II)⋯O3 SOOSO3 - ), which mediated ROS generation and E. coli K-12 oxidation. The increased cell-envelope lesions consequently aggravated intracellular protein depletion and genome damage to cause definite bacterial death. The NP still maintained good physiochemical structure and stable activity even after 4 cycle. Moreover, NP/PS system also exhibited good E. coli K-12 inactivation efficiency in authentic water matrices like surface water and effluents of secondary wastewater. Graphical abstract: Highlights: Natural magnetic pyrrhotite showed notable catalytic activity to PS. Effects of pH, NOM, bicarbonate, oxygen on reactivity of NP/PS were studied. The bactericidal role of generated ROS ranked as .SO4 − > OH > H2 O2 . Charge transfer complex (≡Fe(II)⋯O3 SOOSO3 - ) was formed in NP/PS system. Cell-envelope lesions aggravated biomolecular damage to cause bacterial death.