The influence of Cu(II) on the decay of monochloramine

Abstract

a b s t r a c tMaintenance of monochloramine concentration during water disinfection is important to ensure the microbial safety of drinking water. The decay of monochloramine always occurs and some substances present in the water can accelerate this process. Copper often exists in ionic form in water, but the effect of Cu(II) on the decomposition of monochloramine is largely unknown. In this paper, a series of experiments were carried out under varying conditions of pH, Cu(II) and initial monochloramine concentrations. Results showed that the decomposition rate of monochloramine was greatly enhanced by Cu(II), and this enhancement decreased with the increase of solution pH and the decrease of Cu(II) concentration. It was proposed that the monochloramine decomposition in the presence of Cu(II) was catalyzed via complexation between Cu(II) and monochloramine. The X-ray absorption fine structure experiments gave further evidence to this conclusion. The results will provide useful information for selecting proper disinfection method in water disinfection where Cu(II) exists and reasonable monochloramine dosage during chloramination.

Critical Review: Propensity of Premise Plumbing Pipe Materials to Enhance or Diminish Growth of Legionella and Other Opportunistic Pathogens

“…While chloramine is relatively non-reactive, iron oxide scale and associated nitrifying biofilms can cause relatively rapid monochloramine decay [216,217]. The reactivity of copper pipes and copper oxides is typically between plastics and iron and chemically catalyzes both chlorine and chloramine degradation [43,54,156,[218][219][220]. Higher pH and the existence of phosphate can help maintain disinfectant residual levels in both iron and copper pipes [26,54].…”

Cu(II)-catalyzed THM formation during water chlorination and monochloramination: A comparison study

“…Based on the studies described above as well as our previous work [18,19], it is reasonably expected that copper tends to play an important role in THM formation upon water chlorination and monochloramination. Therefore, this study was to comparatively investigate the catalytic effect of Cu(II) on THM formation during chlorination and monochloramination of HA and simple model compounds, and further clarify the reaction mechanism through identification of reaction intermediates.…”

Microelectrode investigation of iron and copper surfaces aged in presence of monochloramine

“…Presumably, at this pH, orthophosphate presence inhibited copper release from its corrosion and reaction according to Equation to produce cuprous ion; therefore, slowing the reaction presented as Equation . Furthermore and according to Fu, Qu, Liu, Qiang, et al (2009) and Fu, Qu, Liu, Zhao, and Qiang (2009), the reactions between monochloramine and cuprous ions are expected to occur mainly during the initial stages of copper corrosion when low levels of cupric ions are present, which represented the experimental conditions tested.…”