Assessment of the impact of chloride on the formation of chlorinated by products in the presence and absence of electrochemically activated sulfate

Farhat, Ali and Keller, Jurg and Tait, Stephan and Radjenovic, Jelena (2017) Assessment of the impact of chloride on the formation of chlorinated by products in the presence and absence of electrochemically activated sulfate. Chemical Engineering Journal, 330. pp. 1265-1271. ISSN 1385-8947

Abstract

Boron-doped diamond anodes are widely used for electrochemical oxidation of contaminants, due to their excellent capability to form hydroxyl radicals as well as inorganic radicals such as chloride, phosphate, and sulphate radicals, electrogenerated when their corresponding anions are present in the influent water. Addition of sulphate increases the electrooxidation rates of organic pollutants at boron-doped diamond (BDD) anode. However, the effect of chloride on the electrooxidation is considered to be less straightforward. The anodic oxidation of chloride yields chlorine and hypochlorous acid/hypochlorite, besides chloride radicals, and may form toxic chlorine oxyanions at higher applied potentials. The present study investigates such implications of chloride ions to the electro oxidation of a natural organic matter surrogate, resorcinol, in the presence of sulfate. The presence of sulfate yielded up to eightfold enhancement in the removal of resorcinol and total organic carbon (TOC) at both acidic and neutral pH. Chloride addition to Na2SO4 inhibited the resorcinol oxidation and mineralization, whereas it enhanced resorcinol oxidation in NaNO3. However, sulfate inhibited the electrogeneration of chlorinated organics by ∼2–4 folds compared to nitrate at low chloride concentrations i.e., [SO4 1−]:[Cl−] > 1). Although increasing the pH from pH 2 to pH 7 yielded a two times lower amount of chlorinated organics, electrolysis in Na2SO4 anolyte enhanced the generation of undesired chlorate and perchlorate at both acidic and neutral pH.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Files associated with this item cannot be displayed due to copyright restrictions.
Faculty/School / Institute/Centre: Current - Faculty of Health, Engineering and Sciences - School of Civil Engineering and Surveying
Date Deposited: 23 Apr 2019 01:41
Last Modified: 30 May 2019 03:31
Uncontrolled Keywords: sulfate radical, electrochemical oxidation, BDD anode, chlorinated byproducts, oxychlorine species
Fields of Research : 09 Engineering > 0907 Environmental Engineering > 090703 Environmental Technologies
Socio-Economic Objective: D Environment > 96 Environment > 9611 Physical and Chemical Conditions of Water > 961101 Physical and Chemical Conditions of Water for Urban and Industrial Use
Identification Number or DOI: 10.1016/j.cej.2017.08.033
URI: http://eprints.usq.edu.au/id/eprint/36082

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