Insight into the generation of hydroxyl radicals by photo-electrocoagulation process via active chlorine

Treviño‐Reséndez, José; Medel, Alejandro; Mijaylova, Petia; Robles, Irma; Rodríguez-Valadéz, Francisco J.; Godı́nez, Luis A.; Meas, Y.

doi:10.1007/s13762-021-03351-w

Cited by 11 publications

(3 citation statements)

References 69 publications

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“…The hydroxyl radical is typically generated in a controllable fashion via two different methods: (i) by Fenton-like reactions , and (ii) at electrochemical/photoelectrochemical interfaces. − Fenton-like reactions are based on the oxidation of a metallic ion or metal complex in the presence of hydrogen peroxide. The most widely used metal for Fenton chemistry is iron.…”

Section: Introductionmentioning

confidence: 99%

Real-Time Detection of Hydroxyl Radical Generated at Operating Electrodes via Redox-Active Adduct Formation Using Scanning Electrochemical Microscopy

et al. 2022

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The hydroxyl radical (•OH) is one of the most attractive reactive oxygen species due to its high oxidation power and its clean (photo)(electro)generation from water, leaving no residues and creating new prospects for efficient wastewater treatment and electrosynthesis. Unfortunately, in situ detection of •OH is challenging due to its short lifetime (few ns). Using lifetime-extending spin traps, such as 5,5-dimethyl-1-pyrroline N-oxide (DMPO) to generate the [DMPO–OH]• adduct in combination with electron spin resonance (ESR), allows unambiguous determination of its presence in solution. However, this method is cumbersome and lacks the necessary sensitivity and versatility to explore and quantify •OH generation dynamics at electrode surfaces in real time. Here, we identify that [DMPO–OH]• is redox-active with E 0 = 0.85 V vs Ag|AgCl and can be conveniently detected on Au and C ultramicroelectrodes. Using scanning electrochemical microscopy (SECM), a four-electrode technique capable of collecting the freshly generated [DMPO–OH]• from near the electrode surface, we detected its generation in real time from operating electrodes. We also generated images of [DMPO–OH]• production and estimated and compared its generation efficiency at various electrodes (boron-doped diamond, tin oxide, titanium foil, glassy carbon, platinum, and lead oxide). Density functional calculations, ESR measurements, and bulk calibration using the Fenton reaction helped us unambiguously identify [DMPO–OH]• as the source of redox activity. We hope these findings will encourage the rapid, inexpensive, and quantitative detection of •OH for conducting informed explorations of its role in mediated oxidation processes at electrode surfaces for energy, environmental, and synthetic applications.

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Section: Introductionmentioning

confidence: 99%

Real-Time Detection of Hydroxyl Radical Generated at Operating Electrodes via Redox-Active Adduct Formation Using Scanning Electrochemical Microscopy

et al. 2022

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“…(iii) Side-reaction interference of probe and target radicals perturbs the determination. 21,22 Yu et al used Cl − as a probe to measure the •OH produced in the photolysis of H 2 O 2 . 23 In their system, 16 possible reaction pathways were considered, which presented an obstacle for extrapolation back to initial…”

Section: Introductionmentioning

confidence: 99%

“…The comparable k values indicate a competition of H 2 O 2 with methanol at their similar concentration (eqs and ). Under this condition, the probe methanol only estimates 96% of the total • OH (eq ), while remaining 4% is scavenged by H 2 O 2 , ultimately resulting in an underestimation of •OH value. ( iii ) Side-reaction interference of probe and target radicals perturbs the determination. , Yu et al used Cl – as a probe to measure the •OH produced in the photolysis of H 2 O 2 . In their system, 16 possible reaction pathways were considered, which presented an obstacle for extrapolation back to initial • OH concentration.…”

Section: Introductionmentioning

confidence: 99%

Direct Determination of Absolute Radical Quantum Yields in Hydroxyl and Sulfate Radical-Based Treatment Processes

Yan,

Meng,

Miu

et al. 2024

Environ. Sci. Technol.

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The absolute radical quantum yield ( italicΦ ) is a critical parameter to evaluate the efficiency of radical-based processes in engineered water treatment. However, measuring italicΦ is fraught with challenges, as current quantification methods lack selectivity, specificity, and anti-interference capabilities, resulting in significant error propagation. Herein, we report a direct and reliable time-resolved technique to determine italicΦ at pH 7.0 for commonly used radical precursors in advanced oxidation processes. For H2O2 and peroxydisulfate (PDS), the values of italicΦ •OH and normalΦ normalSO 4 • − at 266 nm were measured to be 1.10 ± 0.01 and 1.46 ± 0.05, respectively. For peroxymonosulfate (PMS), we developed a new approach to determine normalΦ • normalOH normalPMS with terephthalic acid as a trap-and-trigger probe in the nonsteady state system. For the first time, the normalΦ • normalOH normalPMS value was measured to be 0.56 by the direct method, which is stoichiometrically equal to Φ SO 4 • − PMS (0.57 ± 0.02). Additionally, radical formation mechanisms were elucidated by density functional theory (DFT) calculations. The theoretical results showed that the highest occupied molecular orbitals of the radical precursors are O–O antibonding orbitals, facilitating the destabilization of the peroxy bond for radical formation. Electronic structures of these precursors were compared, aiming to rationalize the tendency of the italicΦ values we observed. Overall, this time-resolved technique with specific probes can be used as a reliable tool to determine italicΦ , serving as a scientific basis for the accurate performance evaluation of diverse radical-based treatment processes.

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Synergistic role of active chlorine species and hydroxyl radicals during disinfection and mineralization of carwash wastewater

Medel

González

Treviño-Reséndez

et al. 2023

J Solid State Electrochem

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Insight into the generation of hydroxyl radicals by photo-electrocoagulation process via active chlorine

Cited by 11 publications

References 69 publications

Real-Time Detection of Hydroxyl Radical Generated at Operating Electrodes via Redox-Active Adduct Formation Using Scanning Electrochemical Microscopy

Real-Time Detection of Hydroxyl Radical Generated at Operating Electrodes via Redox-Active Adduct Formation Using Scanning Electrochemical Microscopy

Direct Determination of Absolute Radical Quantum Yields in Hydroxyl and Sulfate Radical-Based Treatment Processes

Synergistic role of active chlorine species and hydroxyl radicals during disinfection and mineralization of carwash wastewater

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