Mechanism of Base Activation of Persulfate

Abstract

Base is the most commonly used activator of persulfate for the treatment of contaminated groundwater by in situ chemical oxidation (ISCO). A mechanism for the base activation of persulfate is proposed involving the base-catalyzed hydrolysis of persulfate to hydroperoxide anion and sulfate followed by the reduction of another persulfate molecule by hydroperoxide. Reduction by hydroperoxide decomposes persulfate into sulfate radical and sulfate anion, and hydroperoxide is oxidized to superoxide. The base-catalyzed hydrolysis of persulfate was supported by kinetic analyses of persulfate decomposition at various base:persulfate molar ratios and an increased rate of persulfate decomposition in D(2)O vs H(2)O. Stoichiometric analyses confirmed that hydroperoxide reacts with persulfate in a 1:1 molar ratio. Addition of hydroperoxide to basic persulfate systems resulted in rapid decomposition of the hydroperoxide and persulfate and decomposition of the superoxide probe hexachloroethane. The presence of superoxide was confirmed with scavenging by Cu(II). Electron spin resonance spectroscopy confirmed the generation of sulfate radical, hydroxyl radical, and superoxide. The results of this research are consistent with the widespread reactivity reported for base-activated persulfate when it is used for ISCO.

Heterogeneous degradation of refractory pollutants by peroxymonosulfate activated by CoOx-doped ordered mesoporous carbon

“…Sulfate radical (SO 4 ÅÀ ) based advanced oxidation processes (AOPs) have attracted increasing attention for their potential capability in the destruction of recalcitrant organic contaminants [1]. Compared with hydroxyl radical ( Å OH, 1.8-2.7 V vs. normal hydrogen electrode (NHE)), SO 4 ÅÀ possesses a series of merits, such as high oxidation selectivity, strong oxidizing capability (2.5-3.1 V vs. NHE) and independence of pH [2].…”

Activation of Persulfate Using an Industrial Iron-Rich Sludge as an Efficient Nanocatalyst for Landfill Leachate Treatment

“…This decrease is because of converting iron ions into iron hydroxide, which is not useful for the activation of PS [34]. By increasing the pH to 9, the removal efficiency improved relatively because the alkaline conditions partially activated PS [35,36]. …”

Birnessite nanorod-mediated decomposition of methylene blue with common oxidants

“…Dyeing and finishing operations produce large quantities of wastewater that contains number of organic dyestuff, which are toxic and potential carcinogenic nature (Reisch 1988). There exist a number of methods for treating these effluents, such as coagulation, adsorption on activated carbon, chemical oxidation (advanced oxidation process-AOPs), and biological treatment (Andreozzy et al 1999;Parag and Aniruddha 2004;Watts and Teel 2006;Furman et al 2009Furman et al , 2010Kitajima et al 1978;Zhou et al 1998). Among them, AOPs have already been used for the treatment of wastewater.…”