Effect of Ozonation on Cyanogen Chloride and Chloral Hydrate Formation
Public Deposited- Last Modified
- February 28, 2019
- Creator
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Smith, Marla Ellen
- Affiliation: Gillings School of Global Public Health, Department of Environmental Sciences and Engineering
- Abstract
- The purpose of this research was to evaluate the impact of ozonation on the formation of chloral hydrate and cyanogen chloride produced by subsequent chlorination and chloramination. Chloral hydrate tends to be formed from chlorination while cyanogen chloride is formed primarily from chloramination. Raw waters and hydrophobic organic extracts were collected from five utilities across the United States to provide diversity in the organic material and water quality characteristics. Chloral hydrate and cyanogen chloride formation were investigated during chlorination and chloramination, both with and without pre-ozonation, of raw waters and model waters prepared from the extracted organic material. The raw waters were also subjected to coagulation experiments prior to post-chlorination and post-chloramination. In addition, ozone dose, total organic carbon (TOC)concentration, total inorganic carbon (TIC) concentration, ozonation pH, bromide ion concentration, and ammonia concentration were varied in the model waters in order to measure the influence of these parameters on chloral hydrate and cyanogen chloride formation. Pre-ozonation enhanced chloral hydrate formation from post-chlorination in all cases, and the extent of this increase was dependent upon the source of organic carbon. Pre-formed monochloramine did not produce appreciable amounts of chloral hydrate. Ozonation pH and TIC concentration were significant factors in determining chloral hydrate yields from post-chlorination, with chloral hydrate concentration decreasing with increasing ozonation pH or increasing TIC concentration. Chloral hydrate concentration from pre-ozonation/post-chlorination did not correlate well with acetaldehyde concentration resulting from pre-ozonation, implying that acetaldehyde is not a principal precursor to chloral hydrate formation. Pre-ozonation enhanced cyanogen chloride formation from post-chloramination. As with chloral hydrate, the degree of the increase depended on the source of organic carbon. Cyanogen chloride formation from post-chloramination was also impacted by ozonation pH and TIC concentration, with cyanogen chloride concentrations decreasing with increasing ozonation pH or increasing TIC concentration. The extent of cyanogen chloride formation from chloramination with pre-formed monochloramine correlated strongly with the concentration of formaldehyde resulting from pre-ozonation. This suggests that formaldehyde, a known oxidation by-product of ozone as well as chlorine, may be a principal precursor to cyanogen chloride formation.
- Date of publication
- December 1994
- DOI
- Resource type
- Rights statement
- In Copyright
- Advisor
- DiGiano, Francis A.
- Singer, Philip
- Crawford-Brown, Douglas J.
- Degree
- Master of Science in Environmental Engineering
- Academic concentration
- Water Resources Engineering
- Degree granting institution
- University of North Carolina at Chapel Hill
- Graduation year
- 1994
- Language
- Deposit record
- 043fb25a-cea5-4ac2-b0d3-5af4a220fe28
Relations
- Parents:
This work has no parents.