Comparative Analysis of Photocatalytic and Electrochemical Degradation of 4-Ethylphenol in Saline Conditions

Robert Brüninghoff, Alyssa K. Van Duijne, Lucas Braakhuis, Pradip Saha, Adriaan W. Jeremiasse, Bastian Mei, Guido Mul*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

12 Citations (Scopus)

Abstract

We evaluated electrochemical degradation (ECD) and photocatalytic degradation (PCD) technologies for saline water purification, with a focus on rate comparison and formation and degradation of chlorinated aromatic intermediates using the same non-chlorinated parent compound, 4-ethylphenol (4EP). At 15 mA·cm-2, and in the absence of chloride (0.6 mol·L-1 NaNO3 was used as supporting electrolyte), ECD resulted in an apparent zero-order rate of 30 μmol L-1·h-1, whereas rates of ?300 μmol L-1·h-1 and ?3750 μmol L-1·h-1 were computed for low (0.03 mol·L-1) and high (0.6 mol·L-1) NaCl concentration, respectively. For PCD, initial rates of ?330 μmol L-1·h-1 and 205 μmol L-1·h-1 were found for low and high NaCl concentrations, at a photocatalyst (TiO2) concentration of 0.5 g·L-1, and illumination at λmax ≈ 375 nm, with an intensity ?0.32 mW·cm-2. In the chlorine mediated ECD approach, significant quantities of free chlorine (hypochlorite, Cl2) and chlorinated hydrocarbons were formed in solution, while photocatalytic degradation did not show the formation of free chlorine, nor chlorine-containing intermediates, and resulted in better removal of non-purgeable hydrocarbons than ECD. The origin of the minimal formation of free chlorine and chlorinated compounds in photocatalytic degradation is discussed based on photoelectrochemical results and existing literature, and explained by a chloride-mediated surface-charge recombination mechanism.

Original languageEnglish
Pages (from-to)8725-9735
JournalEnvironmental Science and Technology
Volume53
Issue number15
DOIs
Publication statusPublished - 8 Jul 2019

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