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Advanced Oxidation Processes for Removal of Emerging Pollutants

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A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Green Chemistry".

Deadline for manuscript submissions: closed (20 April 2023) | Viewed by 11107

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Special Issue Editors

Dr. Miaomiao Ye

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Guest Editor

College of Civil Engineering and Architecture, Zhejiang University, Zhejiang 310058, China
Interests: advanced oxidation processes; emerging contaminants; air-water interfacial solar evaporation; water quality
Special Issues, Collections and Topics in MDPI journals

Dr. Xiaowei Liu

E-Mail Website
Guest Editor

College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058, China
Interests: emerging pollutants; advanced oxidation processes; ozonation; Fenton; activated persulfate; sonication; membrane filtration

Dr. Rong Chen

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Guest Editor

School of Environment, Tsinghua University, Beijing 100084, China
Interests: emerging pollutants removal; photothermal; membrance filtration; interfacial solar heating; photocatalysis

Special Issue Information

Dear Colleagues,

The continuous occurrence of emerging pollutants in the aquatic environment has become a worldwide issue that has received increasing attention. Emerging pollutants consist of a vast and expanding array of anthropogenic and natural substances, including pharmaceutical and personal care products (PPCPs), endocrine disrupting compounds (EDCs), perfluorinated compounds (PFCs), engineered nanoparticles (ENPs), halogenated flame retardants (HFRs), microplastics (MPs), antibiotics resistance gene (ARGs), and many other undetected compounds. Emerging pollutants are usually present in water at trace concentration ranging from a few ng/L to several μg/L. Though the concentration is low, the emerging pollutants are biotoxic, cumulative and persistent, which will bring potential risks to ecosystem and human health. However, the current water and wastewater treatment processes cannot effectively remove emerging pollutants. Technological innovations need to be made to address this concern.

This Special Issue aims to collect papers dealing with the advanced oxidation processes (AOPs) including (but not limited to) photocatalysis, ozonation, Fenton, activated persulfate, sonication for removal of emerging pollutants in polluted water. In addition, a particular focus on new achievements in the field will be appreciated.

Dr. Miaomiao Ye
Dr. Xiaowei Liu
Dr. Rong Chen
Guest Editors

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Keywords

emerging pollutants
aquatic environment
advanced oxidation processes
photocatalysis
ozonation
Fenton
activated persulfate
sonication

Published Papers (7 papers)

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Research

16 pages, 1300 KiB

Open AccessArticle

Structural Features Promoting Photocatalytic Degradation of Contaminants of Emerging Concern: Insights into Degradation Mechanism Employing QSA/PR Modeling

by Antonija Tomic, Marin Kovacic, Hrvoje Kusic, Panaghiotis Karamanis, Bakhtiyor Rasulev and Ana Loncaric Bozic

Molecules 2023, 28(6), 2443; https://doi.org/10.3390/molecules28062443 - 7 Mar 2023

Viewed by 1202

Abstract

Although heterogeneous photocatalysis has shown promising results in degradation of contaminants of emerging concern (CECs), the mechanistic implications related to structural diversity of chemicals, affecting oxidative (by HO•) or reductive (by O₂•⁻) degradation pathways are still scarce. In this study, the degradation extents and rates of selected organics in the absence and presence of common scavengers for reactive oxygen species (ROS) generated during photocatalytic treatment were determined. The obtained values were then brought into correlation as K coefficients (

M_{HO •}

M_{O_{2} •^{-}}

), denoting the ratio of organics degraded by two occurring mechanisms: oxidation and reduction via HO• and O₂•⁻. The compounds possessing K >> 1 favor oxidative degradation over HO•, and vice versa for reductive degradation (i.e., if K << 1 compounds undergo reductive reactions driven by O₂•⁻). Such empirical values were brought into correlation with structural features of CECs, represented by molecular descriptors, employing a quantitative structure activity/property relationship (QSA/PR) modeling. The functional stability and predictive power of the resulting QSA/PR model was confirmed by internal and external cross-validation. The most influential descriptors were found to be the size of the molecule and presence/absence of particular molecular fragments such as C − O and C − Cl bonds; the latter favors HO•-driven reaction, while the former the reductive pathway. The developed QSA/PR models can be considered robust predictive tools for evaluating distribution between degradation mechanisms occurring in photocatalytic treatment. Full article

(This article belongs to the Special Issue Advanced Oxidation Processes for Removal of Emerging Pollutants)

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12 pages, 1982 KiB

Open AccessArticle

Correlation Analysis of the Carboxyl and Carbonyl Groups of Natural Organic Matter and the Formation Potential of Trihalomethanes and Chloral Hydrate

by Xinwei Zhu, Minghua Li, Pengwei Yan, Jimin Shen, Jing Kang and Zhonglin Chen

Molecules 2022, 27(21), 7454; https://doi.org/10.3390/molecules27217454 - 2 Nov 2022

Viewed by 1151

Abstract

Natural organic matter (NOM) has always been considered the main precursor of disinfection by-products (DBPs) during the chlorine disinfection of drinking water. This research focuses on investigating the correlation between the functional group (carboxyl and carbonyl groups) content of NOM and the formation of trichloromethane (TCM) and chloral hydrate (CH). The quantitative determination of carboxyl groups, carbonyl groups, TCM, and CH were conducted during the drinking water treatment processes with different coagulant dosages and with/without pre-oxidation by KMnO₄ or NaClO. The most appropriate coagulant for the removal of conventional components was polyaluminum chloride (PAC), and the dosage was 110 mg/L. Up to 43.7% and 14.5% of the carboxyl and carbonyl groups, respectively, were removed through the coagulation and sedimentation processes, which can be enhanced by increasing PAC dosage. The filtration process further increased the removal rates of these two functional groups to 59.8% and 33.5%, respectively. The formation potential of the TCM and CH decreased as the PAC dosage increased. Pre-oxidation by KMnO₄ (0.8–1.0 mg/L) effectively controlled the formation of DBPs while increasing the carboxyl and carbonyl group content. Pre-oxidation by NaClO decreased the formation of TCM rather than CH, and a suitable amount (0.5–1.0 mg/L) decreased the carboxyl and carbonyl groups. It was found that there was a good linear correlation between carboxyl groups and TCM and CH. The linear fit R² values of the carboxyl groups to TCM and CH were 0.6644 and 0.7957, respectively. The linear fit R² values of the carbonyl groups to TCM and CH were 0.5373 and 0.7595, respectively. Full article

(This article belongs to the Special Issue Advanced Oxidation Processes for Removal of Emerging Pollutants)

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17 pages, 5187 KiB

Open AccessArticle

Synergistic Catalytic Performance of Toluene Degradation Based on Non-Thermal Plasma and Mn/Ce-Based Bimetal-Organic Frameworks

by Xing Rong, Qing Cao, Yan Gao, Tao Luan, Yanteng Li, Quanyou Man, Zhanchao Zhang and Baoming Chen

Molecules 2022, 27(21), 7363; https://doi.org/10.3390/molecules27217363 - 29 Oct 2022

Cited by 8 | Viewed by 1337

Abstract

A series of Mn/Ce-based bimetal-organic frameworks, recorded as MCDx (x = 1, 2, 4, 6), were prepared by a solvothermal synthesis method to explore their effects and performance in the synergistic catalysis of toluene under the irradiation of non-thermal plasma. The catalytic properties of different manganese loadings in MCDx for degradation of toluene were investigated. The microphysical structures of the material were analyzed by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The results showed that a MCDx coupling with non-thermal plasma can greatly improve the degradation efficiency, the energy efficiency and the CO₂ selectivity, and could also significantly reduce the generation of O₃ in the by-products. Among the test samples, MCD6 with Mn:Ce = 6:1 (molar ratio) showed the best catalytic performance and stability, exhibited toluene catalytic efficiency 95.2%, CO₂ selectivity 84.2% and energy efficiency 5.99 g/kWh, and reduced O₃ emission concentration 81.6%. This research provides a reference for the development and application of synergistic catalysis based on bimetal-organic frameworks and non-thermal plasma in the reduction of industrial volatile organic compounds. Full article

(This article belongs to the Special Issue Advanced Oxidation Processes for Removal of Emerging Pollutants)

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12 pages, 2428 KiB

Open AccessArticle

Inhibition of Phenol from Entering into Condensed Freshwater by Activated Persulfate during Solar-Driven Seawater Desalination

by Xiaojiao Zhou, Ningyao Tao, Wen Jin, Xingyuan Wang, Tuqiao Zhang and Miaomiao Ye

Molecules 2022, 27(21), 7160; https://doi.org/10.3390/molecules27217160 - 23 Oct 2022

Cited by 3 | Viewed by 1434

Abstract

Recently, solar-driven seawater desalination has received extensive attention since it can obtain considerable freshwater by accelerating water evaporation at the air–water interface through solar evaporators. However, the high air–water interface temperature can cause volatile organic compounds (VOCs) to enter condensed freshwater and result in water quality safety risk. In this work, an antioxidative solar evaporator, which was composed of MoS₂ as the photothermal material, expandable polyethylene (EPE) foam as the insulation material, polytetrafluoroethylene (PTFE) plate as the corrosion resistant material, and fiberglass membrane (FB) as the seawater delivery material, was fabricated for the first time. The activated persulfate (PS) methods, including peroxymonosulfate (PMS) and peroxodisulfate (PDS), were applied to inhibit phenol from entering condensed freshwater during desalination. The distillation concentration ratio of phenol (R_D) was reduced from 76.5% to 0% with the addition of sufficient PMS or PDS, which means that there was no phenol in condensed freshwater. It was found that the Cl⁻ is the main factor in activating PMS, while for PDS, light, and heat are the dominant. Compared with PDS, PMS can make full utilization of the light, heat, Cl⁻ at the evaporator’s surface, resulting in more effective inhibition of the phenol from entering condensed freshwater. Finally, though phenol was efficiently removed by the addition of PMS or PDS, the problem of the formation of the halogenated distillation by-products in condensed freshwater should be given more attention in the future. Full article

(This article belongs to the Special Issue Advanced Oxidation Processes for Removal of Emerging Pollutants)

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18 pages, 4423 KiB

Open AccessArticle

Enhanced Degradation of Antibiotic by Peroxydisulfate Catalysis with CuO@CNT: Simultaneous ¹O₂ Oxidation and Electron-Transfer Regime

by Jia Liu, Chao Ding, Sicheng Gong, Kun Fu, Huiping Deng and Jun Shi

Molecules 2022, 27(20), 7064; https://doi.org/10.3390/molecules27207064 - 19 Oct 2022

Cited by 1 | Viewed by 1736

Abstract

The nonradical process in the peroxydisulfate (PDS) oxidation system is a promising method for antibiotic removal in water. In this study, CuO@CNT was successfully synthesized by a facile approach to catalyze PDS. The removal efficiency of the antibiotic sulfamethoxazole (SMX) was 90.6% in 50 min, and the stoichiometric efficiency (ΔSMX/ΔPDS) was 0.402. The very different degradation efficiency of common organic contaminants revealed the selective oxidation of the surveyed system. The process of ¹O₂ oxidation and the electron-transfer regime was exhibited by chemical quenching tests, electron paramagnetic resonance (EPR) determination, a UV–vis spectrophotometer, X-ray photoelectron spectroscopy (XPS) detection, and cyclic voltammetry (CV) measurements. Sustainable catalysis was promoted by the circulation between the surface electron-rich centers of Cu(II) and Cu(III). Dissolved oxygen (DO) and a metastable Cu(III) intermediate contributed to the generation of ¹O₂. Still, a portion of SMX was removed by the mildly activated PDS. Moreover, the influence factors (pH, dosage, water matrix) were examined, and suppressions were acceptable by common anions and real water. Distinguished from the radical process, unique intermediate products were ascertained via the theoretical calculation and liquid chromatography–mass spectrometry (LC-MS) detection. Furthermore, CuO@CNT showed a satisfactory activation ability in the cycling experiments. Overall, this study developed CNT to be a supporter of CuO, unveiled the mechanism of catalysis, and evaluated the application potential of the nonradical process. Full article

(This article belongs to the Special Issue Advanced Oxidation Processes for Removal of Emerging Pollutants)

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12 pages, 2286 KiB

Open AccessArticle

Heterogeneous Catalysis of Ozone Using Iron–Manganese Silicate for Degradation of Acrylic Acid

by Yue Liu, Congmin Wang, Rong Guo, Juexiu Li, Quan Zhao, Weiqiang Wang, Fei Qi, Haifang Liu, Yang Li and Huifan Zheng

Molecules 2022, 27(15), 4973; https://doi.org/10.3390/molecules27154973 - 5 Aug 2022

Cited by 1 | Viewed by 1545

Abstract

Iron–manganese silicate (IMS) was synthesized by chemical coprecipitation and used as a catalyst for ozonating acrylic acid (AA) in semicontinuous flow mode. The Fe-O-Mn bond, Fe-Si, and Mn-Si binary oxide were formed in IMS on the basis of the results of XRD, FTIR, and XPS analysis. The removal efficiency of AA was highest in the IMS catalytic ozonation processes (98.9% in 15 min) compared with ozonation alone (62.7%), iron silicate (IS) catalytic ozonation (95.6%), and manganese silicate catalytic ozonation (94.8%). Meanwhile, the removal efficiencies of total organic carbon (TOC) were also improved in the IMS catalytic ozonation processes. The IMS showed high stability and ozone utilization. Additionally, H₂O₂ was formed in the process of IMS catalytic ozonation. Electron paramagnetic resonance (EPR) analysis and radical scavenger experiments confirmed that hydroxyl radicals (•OH) were the dominant oxidants. Cl⁻, HCO₃⁻, PO₄³⁻, Ca²⁺, and Mg²⁺ in aqueous solution could adversely affect AA degradation. In the IMS catalytic ozonation of AA, the surface hydroxyl groups and Lewis acid sites played an important role. Full article

(This article belongs to the Special Issue Advanced Oxidation Processes for Removal of Emerging Pollutants)

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11 pages, 3644 KiB

Open AccessArticle

Removal of Carbamazepine in Aqueous Solution by CoS₂/Fe²⁺/PMS Process

by Tingting Wu, Huan Peng, Xiaowei Liu and Ruijin Wu

Molecules 2022, 27(14), 4524; https://doi.org/10.3390/molecules27144524 - 15 Jul 2022

Cited by 3 | Viewed by 1535

Abstract

Carbamazepine (CBZ), as a typical pharmaceutical and personal care product (PPCP), cannot be efficiently removed by the conventional drinking water and wastewater treatment process. In this work, the CoS₂/Fe²⁺/PMS process was applied for efficient elimination of CBZ. The CBZ removal efficiency of CoS₂/Fe²⁺/PMS was 2.5 times and 23 times higher than that of CoS₂/PMS and Fe²⁺/PMS, respectively. The intensity of DMPO-HO• and DMPO-

{SO}_{4}^{• -}

followed the order of Fe²⁺/PMS < CoS₂/PMS < CoS₂/Fe²⁺/PMS, also suggesting the CoS₂/Fe²⁺/PMS process has the highest oxidation activity. The effects of reaction conditions (e.g., CoS₂ dosage, Fe²⁺ concentration, PMS concentration, initial CBZ concentration, pH, temperature) and water quality parameters (e.g.,

{SO}_{4}^{2 -}

{NO}_{3}^{-}

H_{2} {PO}_{4}^{-}

{Cl}^{-}

{NH}_{4}^{+}

, humic acid) on the degradation of CBZ were also studied. Response surface methodology analysis was carried out to obtain the best conditions for the removal of CBZ, which are: Fe²⁺ = 70 µmol/L, PMS = 240 µmol/L, CoS₂ = 0.59 g/L. The sustainability test demonstrated that the repeated use of CoS₂ for 8 successive cycles resulted in little function decrease (<10%). These findings suggest that CoS₂/Fe²⁺/PMS may be a promising method for advanced treatment of tailwater from sewage treatment plant. Full article

(This article belongs to the Special Issue Advanced Oxidation Processes for Removal of Emerging Pollutants)

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