Sulfate Radical-based Advanced Oxidation Processes Research Articles

Wastewater Treatment: The Emergence of Cobalt Ferrite and Its Composites in Sulfate Radical-Based Advanced Oxidation Processes

Wastewater Treatment: The Emergence of Cobalt Ferrite and Its Composites in Sulfate Radical-Based Advanced Oxidation Processes

New insights into antifouling property and interfacial mechanism in photo-Fenton membrane distillation

Membrane distillation (MD), boasting high interception efficiency and low operational pressures, emerges as an innovative membrane technology. However, the occurrence of membrane fouling due to interaction between natural organic matter (NOM) and inorganic ions during the MD process curtails water purification efficiency, thereby constraining its potential applications. To address this quandary, this study integrates sulfate radical-based advanced oxidation processes (SR-AOPs) into MD technology to bolster membrane fouling control. A straightforward hydrothermal method coupled with vacuum filtration was employed to synthesize a Co3O4/Nitrogen-modified carbon quantum dots (NCDs)/PVDF (CN-PVDF) membrane for the first time, which was utilized in the MD treatment of simulated humic acid (HA) wastewater. Under visible light irradiation (1.9 kW/m2), CN-PVDF membrane activation of peroxymonosulfate (PMS) effectively altered the chemical attributes of the MD feed solution and reduced organic matter concentration. Moreover, it dismantled the carboxyl sites on HA that interact with Ca2+, consequently attenuating the formation of organic–inorganic complex pollutants. The XDLVO analysis showcased that photo-Fenton oxidation led to a diminishment in pollutant hydrophobicity, correlating with a 17.59 kT reduction in pollutant-membrane adsorption and a 7.47 kT amplification in adhesion barriers. This strategy transformed the initial two-stage fouling mode into a singular one, which significantly decreased the flux decline and the fouling layer thickness. Furthermore, the CN-PVDF membrane demonstrated self-cleaning capabilities via photo-Fenton. This study advances an innovative approach to bolster the fouling resistance of MD membranes and provides substantial theoretical support for the integration of SR-AOPs and MD technologies.

Efficiency and mechanism of phosphoric acid modified biochar loaded nanoscale zero-valent iron activated peroxymonosulfate for the degradation of bisphenol A

The degradation efficiency of bisphenol A (BPA) using sulfate radical-based advanced oxidation processes still requires further improvement. Herein, we prepared phosphoric acid-modified biochar-supported nZVI (PBC/nZVI) through liquid-phase reduction. Under optimized conditions, including a PBC/nZVI dosage of 1.2 g/L, pH 9.0, and PMS concentration of 2.0 mmol/L, the BPA degradation rate reached up to 92.66 % within 60 min with the mineralization rate of 45.5 %. The presence of Cl−, HCO3− and CO32− promoted the degradation of BPA, while NO3− had minimal effect. Conversely, H2PO4− and humic acid exhibited varying degrees of inhibition. The degradation of BPA involved four reactive oxygen species (•OH, SO4•−, O2•−, and 1O2), with 1O2 playing a prominent role. The pathways of •OH-induced oxidation and SO4•−-induced hydroxylation were identified as the mechanisms through which BPA was degraded. These findings highlighted the potential of PBC/nZVI as a rapid and efficient material for BPA degradation.

Highly efficient peroxymonosulfate activation by CoFe2O4@attapulgite–biochar composites: Degradation properties and mechanism insights

Sulfate radical-based advanced oxidation processes (SR-AOPs) have been considered as a promising approach for degrading organic pollutants. Herein, CoFe2O4 anchored on attapulgite-biochar composites (CoFe2O4@ATP–BC) were synthesized by a sol-gel co-pyrolysis method and showed excellent catalytic performance, reusability and stability in activating peroxymonosulfate (PMS) for the degradation of Rhodamine B (RhB). The effects of PMS concentration, catalyst dosage, temperature, initial pH, NOM and inorganic ions on the removal of RhB were investigated. The radical quenching experiments and electron paramagnetic resonance (EPR) measurement confirmed that 1O2, O2∙− and surface-bound ∙OH and SO4∙− were major reactive oxygen species (ROS) in the RhB degradation by CoFe2O4@ATP–BC/PMS system, indicating that radical and non-radical degradation pathways were both involved. The possible catalytic mechanism of PMS by CoFe2O4@ATP–BC was proposed including the interface reaction and bulk reaction. The main degradation intermediates were identified by liquid chromatograph-mass spectrometry (LC-MS), and three possible degradation pathways of RhB were deduced accordingly. In general, the CoFe2O4@ATP–BC/PMS system provided fundamentals of theoretical and applied research to further develop supported bimetallic oxides for advanced oxidation treatment of organic wastewater.

Activation of peroxydisulfate via BiCoFe-layered double hydroxide for effective degradation of aniline.

The sulfate radical-based advanced oxidation processes (SR-AOPs) is a promising method for the degradation of pollutants, with the development of highly efficient catalysts for persulfate activation has been widely concerned. The novel BiCoFe-LDH (BCF-x) was synthesized successfully by coprecipitation method, which can activate peroxydisulfate (PDS) efficiently to degrade aniline. Comparative analysis with pure CoFe-LDH revealed a remarkable increase in reaction rate constant by approximately 14.66 times; the degradation rate of aniline (10mg/L) was 100% in 60min with the condition of 0.5g/L BCF-1.5 and 0.5g/L PDS, due to BCF-1.5 which was characterized as a complex of CoFe-LDH and Bi2O2CO3, promoting electron transport to improve the efficiency of activated PDS. In the reaction system, SO4•-, ·OH, and 1O2 were responsible for the aniline degradation and ·OH was the primary one. Furthermore, this work proposes a reaction electron transfer catalytic mechanism, which provided a new insight and good application prospect for efficient activation of PDS for pollutant degradation.

Powdered activated carbon (PAC)-assisted peroxymonosulfate activation for efficient urea elimination in ultrapure water production from reclaimed water

Urea is a problematic pollutant in reclaimed water for ultrapure water (UPW) production. The sulfate radical-based advanced oxidation process (SR-AOP) has been recognized as an effective method for urea degradation. However, conventional metal-based catalysts for peroxymonosulfate (PMS) activation are unsuitable for UPW production due to issues related to metal ion leaching. In this study, the use of powdered activated carbon (PAC) was investigated for the removal of urea from reclaimed water. The PAC exhibited a high degree of defects (ID/IG = 1.709) and various surface oxygen functional groups (C–OH, C=O, and C–O), which greatly enhanced its catalytic capability. The PAC significantly facilitated PMS activation in the PMS + PAC system, leading to the complete urea decomposition. The PMS + PAC system demonstrated excellent urea removal efficiency within a wide pH range, except for pH < 3. Among the various anions present, the CO32− and PO43− inhibited urea degradation, while the coexistence of Cl− promoted urea removal. Furthermore, the feasibility test was evaluated using actual reclaimed water. The quenching test revealed that SO4−·, ·OH, and O2−· played crucial roles in the degradation of urea in the PAC-assisted SR-AOP. The oxygen functional groups (C–OH and O–C=O) and defect sites of PAC clearly contributed to PMS activation.

Bimetallic iron-nickel phosphide as efficient peroxymonosulfate activator for tetracycline hydrochloride degradation: Performance and mechanism

Sulfate radical-based advanced oxidation processes with (SR-AOPs) are widely employed to degrade organic pollutants due to their high efficiency, cost-effectiveness and safety. In this study, a highly active and stable FeNiP was successfully prepared by reduction and heat treatment. FeNiP exhibited high performance of peroxymonosulfate (PMS) activation for tetracycline hydrochloride (TC) removal. Over a wide pH range, an impressive TC degaradation efficiency 97.86% was achieved within 60 min employing 0.1 g/L FeNiP and 0.2 g/L PMS at room temperature. Both free radicals of SO4·-, ·OH, ·O2− and non-free radicals of 1O2 participated the TC degradation in the FeNiP/PMS system. The PMS activation ability was greatly enhanced by the cycling between Ni and Fe bimetal, and the active site regeneration was achieved due to the existence of the negatively charged Pn−. Moreover, the FeNiP/PMS system exhibited substantial TC degradation levels in both simulated real-world disturbance scenarios and practical water tests. Cycling experiments further affirmed the robust stability of FeNiP catalyst, demonstrating sustained degradation efficiency of approximately 80% even after four cycles. These findings illuminate its promising potential across natural water bodies, presenting an innovative catalyst construction approach for PMS activation in the degradation of antibiotic pollutants.

Enhanced antibiotic degradation via photo-assisted peroxymonosulfate over graphitic carbon nitride nanosheets/CuBi2O4: Highly efficiency of oxygen activation and interfacial charge transfer

Improving the activation capacity of peroxymonosulfate (PMS) to increase radical and non-radical production is critical for antibiotic degradation. However, how to boost reactive oxygen species (ROS) and speed interfacial charge transfer remains an essential challenge. We report a coupling system of 10 %CNNS/CuBi2O4 photocatalyst and sulfate radical-based advanced oxidation processes (SO4−-AOPs) to enhance the activation of PMS and improve antibiotic degradation. Owing to highly efficient oxygen activation and interfacial charge transfer, the degradation efficiency of the photo-assisted PMS system was as high as 51.6 times and 2.8 times that of photocatalyst and SO4−-AOPs alone, respectively. Importantly, the highly efficient oxygen activation resulted in the production of O2−, which in turn could utilize the excess electrons generated through efficient interfacial charge transfer to convert into non-radical 1O2. The total organic carbon (TOC) elimination effectiveness of the photo-assisted PMS system reached 82 % via the synergy of radicals and non-radicals (O2−, OH, 1O2, SO4−, h+). This system also had excellent potential for reducing the generation and toxicity of disinfection by-products (DBPs), as evidenced through significant reductions in concentrations of trichloromethane (TCM), dichloroacetic acid (DCAA), and trichloronitromethane (TCNM) by 76 %, 64 %, and 35 %, respectively, providing an effective and eco-friendly strategy for antibiotic treatment.

Photocatalytic Degradation of Rhodamine B via Fe-g-C3N4 Activated Sulfate Radical-Based Advanced Oxidation Processes and the Synergistic Mechanism

Photocatalytic Degradation of Rhodamine B via Fe-g-C3N4 Activated Sulfate Radical-Based Advanced Oxidation Processes and the Synergistic Mechanism

Green rGO/FeNPs nanocomposites activated peroxydisulfate for the removal of mixed 17β-estradiol and estriol

Reduced graphene oxide/iron nanoparticles (rGO/FeNPs) synthesized by the chemical method have been used in Fenton oxidation of organic contaminants, yet little is known about biosynthesized rGO/FeNPs using green tea extract (GT) as how to activate persulfate in sulfate radical-based advanced oxidation processes. In this study, rGO/FeNPs were used to activate peroxydisulfate (PDS) for 17β-estradiol (βE2) and estriol (E3) removal. The rGO/FeNPs-PDS system removed 83.6% of βE2 and 62.5% of E3 within 240 min, which was confirmed by a combination of adsorption and degradation via both radical and non-radical pathways. Four main reactive species in βE2 and E3 degradation were observed, i.e., hydroxyl radical (·OH), sulfate radical (SO4·−), singlet oxygen (1O2) and electron transfer, with the respective contributions of ·OH (32.9 and 34.7%), SO4·− (16.1 and 19.7%), 1O2 (12.2 and 14.1%) and electron transfer (8.0 and 7.2%). Analysis of X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR), Electron Paramagnetic Resonance (EPR) and electrochemical measurements all indicated that beside the well-known role of Fe, CO from rGO through the generation of ·OH, SO4·−, 1O2 and electron transfer, as well as GT through electron transfer also participated in the activation of PDS. Finally, the degradation pathways of βE2/E3 were proposed. Overall, this study provides a new insight into the biosynthesis of rGO/FeNPs to activate PDS for the oxidation of mixed emerging contaminants.

Pilot-scale sulfate radical-based advanced oxidation for wastewater reuse: simultaneous disinfection, removal of contaminants of emerging concern, and antibiotic resistance genes

Wastewater reuse addresses water scarcity, but contaminants of emerging concern (CECs), pathogens and antibiotic resistance genes (ARGs) pose health and environmental risks. The European Union (EU) has enacted Regulation (EU) 2020/741, establishing wastewater reuse standards for agriculture. This study evaluates for the first time the effectiveness of four sulfate radical-based advanced oxidation processes (SR-AOPs), based on the combination of peroxymonosulfate (PMS) with O3 and H2O2, applied at pilot plant, for the simultaneous elimination of microorganisms, CECs, and ARGs, in actual urban wastewater treatment plant (UWWTP) effluents. The system PMS/H2O2/UV-A improved the disinfection effectiveness, compared to PMS/UV-A, especially using a molar ratio 1:3 (0.5 mM PMS:1.5 mM H2O2), achieving complete elimination of total aerobic microorganisms in 90 min. However, this double oxidation system, does not improve CECs removal compared to PMS/UV-A in neither of the two molar ratios studied (1:1 or 1:3), and none of these treatments significantly reduced the prevalence of ARGs. However, the PMS/O3 system demonstrated the ability to remove total aerobic microorganisms in 20 min and Escherichia coli in 5 min, 94 % of CECs, and 6 out of the 8 ARGs, demonstrating to be the most effective treatment. However, the system showed phytotoxicity, inhibiting seed growth by 10–30 %, probably associated with the by-products formed in the reaction between organic matter and ozone. This result highlights that SR-AOPs are promising processes with the capability to achieve the simultaneous removal of different contaminant groups, reducing the risks associated with wastewater reuse. Their application at larger scales is increasingly closer.

Single‐Atom Catalysts Originated from Metal–Organic Frameworks for Sulfate Radical‐Based Advanced Oxidation Processes: Critical Insights into Mechanisms

AbstractThe widely discussed single‐atom catalysts (SACs) are regarded as a kind of attractive material for sulfate radical‐based advanced oxidation processes (SR‐AOPs) owing to their maximum atomic utilization efficiency and outstanding stability. Currently, metal–organic frameworks (MOFs) have appeared as prospective precursors for building SACs due to extensive chelating sites, functional adjustability, and structural tunability. However, there are few critical and systematic reviews about the application of MOF‐derived SACs in SR‐AOPs, especially in‐depth analysis of the mechanisms. Therefore, this review seeks to offer a thorough summary of the development of MOF‐derived SACs in SR‐AOPs. First, the unique advantages of MOFs as derivative precursors for SACs are discussed thoroughly. Afterward, the current synthesis strategies are elaborated categorically to unveil the formation process of single atoms and their coordination environments. Notably, the roles of different reaction sites including the generation of reactive species and mediating electron transfer are further analyzed to explain mechanisms comprehensively. Thereafter, the characterization techniques and theoretical calculations for mechanisms studies are also highlighted. Eventually, critical insights into present challenges and future developments are proposed, which are expected to enhance the catalytic efficiency of MOF‐derived SACs in SR‐AOPs.

CuFeS2 supported on dendritic mesoporous silica-titania for persulfate-assisted degradation of sulfamethoxazole under visible light

Sulfamethoxazole (SMX) is a prevalent sulfonamide antibiotic found in the environment, and it has a variety of detrimental effects on environmental sustainability and water safety. Recently, the combination of photocatalysis and sulfate radical-based advanced oxidation processes (SR-AOPs) has attracted a lot of interest as a viable technique for degradation of refractory pollutants. In this study, a visible light active CuFeS2 supported on dendritic mesoporous silica-titania (CuFeS2-DMST) photocatalyst was synthesized to improve the ability of TiO2 to activate persulfate (PS) by introducing CuFeS2 (Fe2+/Fe3+, Cu+/Cu2+ redox cycles). The CuFeS2-DMST/PS/Vis system demonstrated superior SMX degradation efficiency (88.9%, 0.0146 min−1) than TiO2 because of reduced e-/h+ recombination, excellent charge separation and mobility, and a greater surface area than TiO2. Furthermore, after four consecutive photocatalytic cycles, the system demonstrated moderate stability. From chemical quenching tests, O2●-, h+, 1O2, SO4●- and ●OH were found to be the main reactive oxidizing species. The formed intermediates during the degradation process were identified, and degradation mechanisms were proposed. This study proposes a viable technique for activating PS using a low-cost, stable, and high-surface-area TiO2-based photocatalyst, and this concept can be applied to design photocatalysts for water treatment.

Towards removal of PPCPs by advanced oxidation processes: A review

The continuous influx of emerging contaminants (ECs) into water bodies poses a significant threat to human health. Among these contaminants, pharmaceuticals and personal care products (PPCPs) are of particular concern due to their potential to exert adverse effects even at low concentrations. Therefore, it is imperative to explore methods for their effective removal or reduction to safeguard both human health and the ecological environment. Advanced oxidation processes (AOPs) have received substantial attention as promising treatment methods. AOPs are capable of efficiently treating water by generating reactive oxygen species (ROS) with potent oxidation properties, which can effectively eliminate various contaminants. This review delves into the diverse range of AOPs available, including ozonation, photocatalytic oxidation, the Fenton process, electrochemical oxidation, sulfate radicals-based advanced oxidation processes (SR-AOPs), and more. It also discusses the respective limitations and future prospects of these processes, aiming to provide insights into their potential for addressing the pressing issue of PPCP contamination in water bodies.

Ultrafast degradation of organic pollutants in an Fe3O4-CoS2-x activated persulfate catalytic system with an Fe-Co catalytic cycle involving oxygen and sulfur vacancies

Processes that ensure the rapid degradation of organic pollutants are urgently required in wastewater treatment. Heterogeneous catalysts in sulfate radical-based advanced oxidation processes (SR-AOPs) have a low catalytic efficiency, long reaction time, and are difficult to recover. Rationally designed magnetically separable Fe3O4-CoS2-0.4 that was rich in sulfur and oxygen vacancies was used as an efficient catalyst for peroxymonosulfate (PMS) activation to rapidly degrade various dyes and antibiotics. The synergistic effect of Fe, Co and S on the activation of PMS and the sulfur and oxygen vacancy generated by the composite greatly promoted the catalytic performance, in which the singlet oxygen (1O2) generated was the main active species in the degradation process. Fe3O4-CoS2-0.4 is easily separated from the reaction solution by magnets and shows good recyclability and stability in removing MB, achieving removal rates of 100%, 100% and 96.07% in the first, second and third cycles, respectively. Fe3O4-modified CoS2 also greatly reduces the ion leaching of cobalt ions and the secondary pollution. In addition, for several other typical dyes and antibiotics (metronidazole, phenol, tetracycline, levofloxacin, crystal violet, malachite green, and rhodamine B), high removal rates (100%, 100%, 88.3%, 90.3%, 100%, 100%, and 100%, respectively) were achieved in a short time.

Sulfate radical-based advanced oxidation process effects on tire wear particles aging and ecotoxicity

Tire wear particles (TWPs) are widely distributed in natural water and pose as major pollutants in aquatic environments. In this study, heat-activated persulfate (HPT) and ultraviolet-activated persulfate treatments (UPT) were employed to investigate the influence of sulfate radical (SO4−•)-based advanced oxidation process (SAOPs) on TWP physicochemical properties and to clarify their ecotoxic effects in laboratory-level studies. Results showed that the specific surface areas of TWPs increased after UPT but decreased after HPT. In terms of chemical properties, the increase of oxygen-containing functional groups on the surfaces of TWPs was more evident in UPT than that in HPT. The atrazine (ATZ) adsorption capacity of TWPs after HPT and UPT was increased compared with the untreated TWPs. Atrazine adsorbed by TWPs was easily resolved and released in artificial intestinal fluid (1.89–2.08 mg/g) and artificial gastric fluid (1.60–2.04 mg/g) conditions. Acute toxicity experiments of Photobacterium phosphoreum and SEM-EDS detection results suggested that various heavy metals (e.g., Zn2+, Cu2+) in the TWPs would be released into the water system in SAOPs. ATZ released from TWPs that adsorbed ATZ herbicide, rather than TWPs themselves, had a negative effect on aquatic plant growth (e.g., C. vulgaris). The leaching solution of oxidized TWPs (after HPT and UPT) showed a more significant inhibition effect on the zebrafish survival compared with that of untreated TWPs, which was possibly caused by the generation of oxidation byproducts such as N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine-quinone.

Dual strategies to construct electrospun NiCo2O4/boron-doped LaCoO3 heterojunction catalysts to activate peroxymonosulfate for organic pollutant degradation

The spinel and perovskite-based heterogeneous catalysts play indispensable roles in the sulfate radical-based advanced oxidation process (SR-AOP). In this study, novel electrospun boron-doped NiCo2O4/LaCo1−xBxO3 (NCO/Bx, 0 ≤ x < 1) catalysts were constructed using defect and interface engineering to accelerate peroxymonosulfate (PMS) activation. Due to the synergistic impacts of oxygen vacancies (OVs) and heterointerfaces, NCO/B0.2 demonstrated improved catalytic performance toward the degradation of Orange II (Org II). The NCO/B0.2 catalyst showed a high degree of pH tolerance, with a range of 5.0–11.0, while maintaining a removal rate of 94.2% even after five cycles. The degradation pathway exhibited a preference for non-radical mechanisms, with singlet oxygen (1O2) being the dominant reactive oxygen species. The synthesis method for NCO/Bx exhibits the potential to facilitate rational design and large-scale production of exceptionally effective heterostructured catalysts.

A Perspective on Removal of Cyanotoxins from Water Through Advanced Oxidation Processes.

This perspective discusses the challenges associated with the removal of cyanotoxins from raw water sources for drinking water treatment and the emergence of sulfate radical-based advanced oxidation processes (SR-AOPs) as an effective treatment technique. The advantage of SR-AOPs is that they can be activated using a variety of methods, including heat, UV radiation, and transition metal catalysts, allowing for greater flexibility in treatment design and optimization. In addition, the byproducts of SR-AOPs are less harmful than those generated by •OH-AOPs, which reduces the risk of secondary contamination. SR-AOPs generate sulfate radicals (SO4 •-) that are highly selective to certain organic contaminants and have lower reactivity to background water constituents, resulting in higher efficiency and selectivity of the process. The presence of natural organic matter and transition metals in the natural water body increases the degradation efficiency of SR-AOPs for the cyanotoxins. The bromate formation is also suppressed when the water contaminated with cyanotoxins is treated with SR-AOPs.

A sustainable solution for organic pollutant degradation: Novel polyethersulfone/carbon cloth/FeOCl composite membranes with electric field-assisted persulfate activation

Sulfate radical-based advanced oxidation processes (SR-AOP) and ultrafiltration (UF) membranes have demonstrated effectiveness in treating wastewater. This investigation illuminated a pioneering two-stage procedure for fabricating polyethersulfone/carbon cloth/FeOCl (PES/CC/FeOCl) composite catalytic membranes, exhibiting proficiency in persulfate activation. Evidenced by their distinctively high degradation rates and superior stability, these innovative composite membranes efficaciously obviate tetracycline (TC), showcasing a striking TC degradation rate, with an unparalleled removal ratio peaking at 93% under applied electrical fields. The process underlying persulfate activation and TC degradation was meticulously explored through electron paramagnetic resonance (EPR) and quenching trials. These evaluations unveil that hydroxyl radicals (•OH) and sulfate radicals (SO4•−) primarily drive the eradication of diminutive organic molecules. Subsequent studies emphasized the noteworthy rejection ratio of the PES/CC/FeOCl composite membranes (90%) for sodium alginate (SA), further revealing their exceptional on-line cleansing efficiency in an electrofiltration-associated in-situ oxidation system. In essence, this study proposed a novel approach for the synthesis of composite membranes adept at the catalytic degradation of organic pollutants. This paradigm-shifting research imparted a unique lens to perceive the integration of membrane separation technology, enriching the domain of advanced wastewater treatment strategies.

Assessment of sulfate radical-based advanced oxidation and electrocoagulation processes for spent caustic treatment from olefin unit

Assessment of sulfate radical-based advanced oxidation and electrocoagulation processes for spent caustic treatment from olefin unit