Oxidative Degradation of Methylene Blue via PDS-Based Advanced Oxidation Process Using Natural Pyrite

Liang Sun, Dehao Hu, Ziyu Zhang and Xiaoyan Deng
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Liang Sun: College of Environment and Safety Engineering, Qingdao University of Science and Technology, Qingdao 266042, China
Dehao Hu: College of Environment and Safety Engineering, Qingdao University of Science and Technology, Qingdao 266042, China
Ziyu Zhang: College of Environment and Safety Engineering, Qingdao University of Science and Technology, Qingdao 266042, China
Xiaoyan Deng: College of Environment and Safety Engineering, Qingdao University of Science and Technology, Qingdao 266042, China

IJERPH, 2019, vol. 16, issue 23, 1-12

Abstract: H 2 O 2 - and PDS-based reactions are two typical advanced oxidation processes (AOPs). In this paper, a comparative study of H 2 O 2 /PDS-based AOPs employing natural pyrite as a catalyst to degrade methylene blue (MB) was reported. The adaptive pH range in pyrite/PDS extended from 3 to 11, in contrast to the narrow effective pH range of 3–7 in pyrite/H 2 O 2 . As a result of the iron leaching, a synergistic effect of both homogeneous and heterogeneous catalysis was observed in pyrite/PDS, whereas heterogeneous catalytic oxidation dominated pyrite/H 2 O 2 . Furthermore, the batch results showed that the MB removal by pyrite/PDS was highly dependent on chemical conditions (e.g., pH, pyrite and PDS concentration, temperature). Powerful SO 4 •− was generated by pyrite rapidly under acidic or weakly acidic conditions, while SO 4 •− and PDS were assumed by OH − under alkaline condition. The lower pyrite loading (from 0.1 to 0.5 g/L) was affected the removal efficiency obviously, while the scavenging of SO 4 •− did not seem to be remarkable with the excessive amounts of pyrite (>0.5 g/L). Excessive amounts of PDS (>2 mmol/L) might negatively affect the pyrite/PDS system. The reaction temperature that increased from 20 to 40 °C had a positive effect on the degradation of MB. SEM and XRD showed that the passivation of catalyst did not occur due to the strong acid-production ability of pyrite/PDS, inhibiting the formation of Fe-oxide covering the pyrite surface.

Keywords: advanced oxidation process; pyrite; sulfate radical; methylene blue (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2019
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