1
|
Khan Q, Sayed M, Khan JA, Rehman F, Noreen S, Sohni S, Gul I. Advanced oxidation/reduction processes (AO/RPs) for wastewater treatment, current challenges, and future perspectives: a review. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2024; 31:1863-1889. [PMID: 38063964 DOI: 10.1007/s11356-023-31181-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Accepted: 11/18/2023] [Indexed: 01/18/2024]
Abstract
Advanced oxidation/reduction processes (AO/RPs) are considered as effective water treatment technologies and thus could be used to solve the problem of water pollution. These technologies of wastewater treatment involve the production of highly reactive species such as •OH, H•, e-aq, SO4•-, and SO3•-. These radicals can attack the targeted contaminants present in aqueous media and result in their destruction. The efficiency of AO/RPs is highly affected by various operational parameters such as initial concentration of contaminant, solution pH, catalyst amount, intensity of light source, nature of oxidant and reductant used, and the presence of various ionic species in aquatic media. Among AO/RPs, the solar light-based AO/RPs are most widely used nowadays for contaminant removal from aqueous media because of their high environmental friendliness and cost effectiveness. By using these techniques, almost all types of pollutants can be easily removed from aquatic media within short intervals of time, and hence, the problem of water pollution can be solved effectively. This review focuses on various AO/RPs used for wastewater treatment. The effects of different operational parameters that affect the efficiency of these processes toward contaminant removal have been discussed. Besides, challenges and future recommendations are also briefly provided for the researchers in order to improve the efficiency of these processes.
Collapse
Affiliation(s)
- Qaiser Khan
- Radiation and Environmental Chemistry Laboratory, National Centre of Excellence in Physical Chemistry, University of Peshawar, Peshawar, Pakistan
| | - Murtaza Sayed
- Radiation and Environmental Chemistry Laboratory, National Centre of Excellence in Physical Chemistry, University of Peshawar, Peshawar, Pakistan.
| | - Javed Ali Khan
- Radiation and Environmental Chemistry Laboratory, National Centre of Excellence in Physical Chemistry, University of Peshawar, Peshawar, Pakistan
- Department of Chemistry, Abdul Wali Khan University Mardan, Mardan, 23200, Khyber Pakhtunkhwa, Pakistan
| | - Faiza Rehman
- Department of Chemistry, University of Poonch, Rawalakot, Azad Kashmir, Pakistan
| | - Saima Noreen
- Department of Chemistry, University of Agriculture, Faisalabad, Pakistan
| | - Saima Sohni
- Institute of Chemical Sciences, University of Peshawar, Peshawar, Pakistan
| | - Ikhtiar Gul
- Radiation and Environmental Chemistry Laboratory, National Centre of Excellence in Physical Chemistry, University of Peshawar, Peshawar, Pakistan
| |
Collapse
|
2
|
Barroso-Martínez J, B. Romo AI, Pudar S, Putnam ST, Bustos E, Rodríguez-López J. Real-Time Detection of Hydroxyl Radical Generated at Operating Electrodes via Redox-Active Adduct Formation Using Scanning Electrochemical Microscopy. J Am Chem Soc 2022; 144:18896-18907. [PMID: 36215201 PMCID: PMC9586107 DOI: 10.1021/jacs.2c06278] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Indexed: 11/30/2022]
Abstract
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 E0 = 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.
Collapse
Affiliation(s)
- Jaxiry
S. Barroso-Martínez
- Department
of Chemistry, University of Illinois Urbana−Champaign, Urbana, 600 South Mathews Ave., Urbana, Illinois61801, United States
- Centro
de Investigación y Desarrollo Tecnológico en Electroquímica,
S.C. Parque Tecnológico Querétaro, Sanfandila, Pedro Escobedo, 76703Querétaro, Mexico
| | - Adolfo I. B. Romo
- Department
of Chemistry, University of Illinois Urbana−Champaign, Urbana, 600 South Mathews Ave., Urbana, Illinois61801, United States
| | - Sanja Pudar
- Department
of Chemistry, University of Illinois Urbana−Champaign, Urbana, 600 South Mathews Ave., Urbana, Illinois61801, United States
| | - Seth T. Putnam
- Department
of Chemistry, University of Illinois Urbana−Champaign, Urbana, 600 South Mathews Ave., Urbana, Illinois61801, United States
| | - Erika Bustos
- Centro
de Investigación y Desarrollo Tecnológico en Electroquímica,
S.C. Parque Tecnológico Querétaro, Sanfandila, Pedro Escobedo, 76703Querétaro, Mexico
| | - Joaquín Rodríguez-López
- Department
of Chemistry, University of Illinois Urbana−Champaign, Urbana, 600 South Mathews Ave., Urbana, Illinois61801, United States
| |
Collapse
|