A study of the applicability of various activated persulfate processes for the treatment of 2,4-dichlorophenoxyacetic acid

Abstract

This paper reports an investigation of different persulfate (PS) activations, including PS at 20°C (PS), thermally activated PS at 70°C (T-PS), ferrous-ion activated PS at 20°C [Fe(II)-PS)], hydrogen peroxide activated PS at 20°C, and sodium hydroxide activated PS at 20°C, for degradation of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) in aqueous phase. Several findings were made in this study including the followings: the 2,4-D degradation rates in T-PS and Fe(II)-PS systems were higher than other systems. However, complete degradation of 2,4-D and associated derivatives can be reached in all oxidation systems, with various reaction times. When considering the results of PS consumption during the 48 h reaction time to reach complete 2,4-D degradation, the T-PS system consumed all of the PS while only 10 % of the PS was consumed in the Fe(II)-PS system.

Degradation and mechanism of 2,4-dichlorophenoxyacetic acid (2,4-D) by thermally activated persulfate oxidation

“…For TAP, the initial pH of the solution has an important effect on the existing form of radicals (Liang et al, 2013). Therefore, tests to study the effect of the initial solution pH (3e12) on 2,4-D degradation were conducted under the temperature of 60 C and PS concentration of 18 mM, and the results are depicted in Fig.…”

“…In addition, an excess of Fe 2þ may jeopardize the degradation due to SO 4 À quenching through Eq. (4) (Liang et al, 2013;Gu et al, 2017). Comparably, for TAP systems an increase in temperature could result in a faster generation of SO 4 À .…”

“…Comparably, for TAP systems an increase in temperature could result in a faster generation of SO 4 À . Moreover, TAP is promising and highly effective for the degradation of hazardous contaminants (Liang et al, 2013;Ghauch et al, 2015;Yang et al, 2017). For the degradation of 2,4-D, though there are several researches on the abatement of 2,4-D using the method of TAP, for example, Ku smierek and co-workers compared the various active method to decay 2,4-D, whereas only the effect of pH and PS concentration was studied (Ku smierek et al, 2015).…”

“…For the degradation of 2,4-D, though there are several researches on the abatement of 2,4-D using the method of TAP, for example, Ku smierek and co-workers compared the various active method to decay 2,4-D, whereas only the effect of pH and PS concentration was studied (Ku smierek et al, 2015). Liang and co-workers also observed the different activated ways to decay 2,4-D, while mainly focus on the Fe 2þ /PS system (Liang et al, 2013). Therefore, there still have many unknown parameters that could further discuss.…”

Disposal of hexabromocyclododecane (HBCD) by grinding assisted with sodium persulfate

“…When we increased the mass of PS, the active materials increased correspondingly in theory, which promoted the debromination of HBCD, thus, the high bromine recovery was achieved. However, when we continued to increase the mass of PS, the high concentration of the radicals in the system may have accelerated radical scavenging reactions, 24 causing PS wasting, so, debromination efficiency began to decrease. Obviously, the relatively optimal mass of PS was around 4.29 g.…”