On the kinetics of organic pollutant degradation with Co2+/peroxymonosulfate process: When ammonium meets chloride

Abstract

A large amount of chloride and ammonium ions were produced and released from industrial processes with non-biodegradable organic pollutants to affect efficiencies of advanced oxidation processes (AOPs). Here, the influences of chloride and ammonium ions on Co/peroxymonosulfate (Co/PMS) reaction system, a widely used AOPs to produce sulfate radicals, were investigated by examining the degradation efficiency of an azo dye (Acid Orange 7, AO7). The experimental results showed that a significant decrease in the degradation rate of AO7 was observed in the presence of NH, while a dual effect of chloride on AO7 bleaching appeared. The presence of NHCl was unfavorable for AO7 degradation at low concentration (<20 mM), whereas further addition of NHCl (>20 mM) apparently accelerated AO7 discoloration rate. The apparent effects of the two co-existing inorganic ions were determined by roles of the dominating ions at varied molar ratio of [NH]/[Cl]. The present study may have technical implications for the treatment of industrial wastewater containing diverse ions in practice.

Selective degradation of acetaminophen from hydrolyzed urine by peroxymonosulfate alone: performances and mechanisms

“…This was probably because NH 4 + could be deprotonated to form NH 3 , which then might induce the formation of chloramines that have weak oxidation properties ( eqn (20)–(22) ). 39 Consequently, it might be concluded that Cl − , NH 4 OH, and NH 4 HCO 3 were the primary components involved in accelerating ACE degradation. NH 3 + HOCl → NH 2 Cl + H 2 O NH 2 Cl + HOCl → NHCl 2 + H 2 O NHCl 2 + HOCl → NCl 3 + H 2 O …”

On peroxymonosulfate-based treatment of saline wastewater: when phosphate and chloride co-exist

“…Notably, a dual effect was found on AO7 degradation which is similar to our previous investigations. 22,37 At a low level of chloride (<1 mM), the degradation rate of AO7 declined slightly. However, further addition of chloride (>1 mM) apparently accelerated dye degradation.…”

Carbocatalytic ozonation toward advanced water purification

“…291 Moreover, positive effects of ionic strength on reaction rates were observed in various reaction systems. [292][293][294] Studies suggested that the reaction rates between oxidants and organics raised with the increase in ionic strength. 295 The ionic strength created by different ions might also inuence reaction rates.…”