Slow-release persulfate candle-assisted electrochemical oxidation of 2-methylnaphthalene: Effects of chloride, sulfate, and bicarbonate

Ardie Septian; Won Sik Shin

doi:10.1016/j.jhazmat.2020.123196

Slow-release persulfate candle-assisted electrochemical oxidation of 2-methylnaphthalene: Effects of chloride, sulfate, and bicarbonate

J Hazard Mater. 2020 Dec 5:400:123196. doi: 10.1016/j.jhazmat.2020.123196. Epub 2020 Jun 15.

Authors

Ardie Septian¹, Won Sik Shin²

Affiliations

¹ School of Architecture, Civil, Environmental, and Energy Engineering, Kyungpook National University, Daegu 41566, Republic of Korea.
² School of Architecture, Civil, Environmental, and Energy Engineering, Kyungpook National University, Daegu 41566, Republic of Korea. Electronic address: wshin@knu.ac.kr.

PMID: 32593020
DOI: 10.1016/j.jhazmat.2020.123196

Abstract

Slow-release persulfate candle (PSC)-assisted electrochemical oxidation (ECO) of 2-methylnaphthalene (2-MNA) in an undivided cell using graphite-sheet electrodes was investigated using Fe(II) as an activator. The effects of anions (Cl^-, SO₄^2-, and HCO₃^-) were investigated. In the PSC/ECO/Fe(II), the highest pseudo-first-order rate constant (k_obs) and % removal was achieved by adding Cl^- (2.723 h^-1, 75.2%) followed by SO₄^2- (1.753 h^-1, 63.9 %) and HCO₃^- (0.047 h^-1, 3.3%). Addition of Cl^- played a critical role in improving the removal efficiency by inducing OH and SO₄^- oxidations, while SO₄^2- reduced the efficiency due to non-radical oxidation, as elucidated by electron spin resonance (ESR). Furthermore, in the PSC/ECO/Fe(II) + Cl^-, dominant radical was changed from SO₄^- to OH. Scavenger experiments also confirmed that Cl^- and SO₄^2- ions are controlling the oxidation reaction. Two chlorinated byproducts analyzed by LC-MS were identified in PSC/ECO/Fe(II) + Cl^- system.

Keywords: 2-methylnaphthalene; Electrochemical oxidation; PS candle; Radical; Slow release.

Publication types

Research Support, Non-U.S. Gov't