UV/Chlorine Advanced Oxidation Processes: Factors Influencing p-Cresol Transformation Kinetics
Author
Thakur, Shruti SalilIssue Date
2018Advisor
Sáez, Avelino E.
Metadata
Show full item recordPublisher
The University of Arizona.Rights
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.Abstract
During the last 10 years, endocrine disrupters like nonylphenol (NP) have become a major concern in wastewater and water resources. Existing wastewater treatment plants are not designed to remove and/or degrade these emerging pollutants efficiently. In addition, NP is persistent in the aquatic environment, moderately bioaccumulative, and toxic to aquatic organisms. As a result of NP’s high chemical stability and/or low biodegradability, advanced oxidation processes (AOPs) are being considered for the removal from wastewater and water resources. This research project investigated the kinetics of the degradation of p-cresol, a surrogate used for a common endocrine disrupter, p-nonylphenol by UV/Chlorine AOP. A bench-scale study using a cylindrical glass batch reactor equipped with a low pressure (LP) UV lamp showed that the UV/Chlorine AOP was more efficient than either UV/H2O2 AOP or UV and chlorination alone for the degradation of p-cresol at pH 6 in Milli-Q water. The pseudo first-order rate constant was 5.8 times higher for the UV/Chlorine AOP than for the UV/ H2O2 AOP at a given chemical molar dosage and pH 6. The degradation of p-cresol followed pseudo-first-order reaction kinetics, and the degradation rate constants (kobs) were a function of the p-cresol dose, chlorine dose, solution pH, and the presence of natural organic matter (NOM). Degradation of p-cresol greatly increased with increasing chlorine dose and decreasing solution pH during the UV/Chlorine AOP. Additionally, the presence of NOM in the solution inhibited the degradation of p-cresol. UV photolysis, chlorination, and reactive species (hydroxyl radical (•OH), chlorine radical (•Cl) and chlorine monoxide radical (•OCl)) contributed to the degradation of p-cresol. A MATLAB® mathematical model was designed to stimulate the degradation of p-cresol under various operating parameters. However, the formation and toxicity of the chlorinated by-products should be further assessed.Type
textElectronic Thesis
Degree Name
M.S.Degree Level
mastersDegree Program
Graduate CollegeEnvironmental Engineering