Photo-Fenton-like degradation of antibiotics by inverse opal WO3 co-catalytic Fe2+/PMS, Fe2+/H2O2 and Fe2+/PDS processes: A comparative study

Interfacial OOH* mediated Fe(II) regeneration on the single atom Co-N-C catalyst for efficient Fenton-like processes

Fe(II) regeneration is decisive for highly efficient H2O2-based Fenton-like processes, but the role of cobalt-containing reactive sites in promoting Fe(II) regeneration was overlooked. Herein, a single atom Co-N-C catalyst was employed in Fe(II)/H2O2 system to promote the degradation of diverse organic contaminants. The EPR and quenching experiments indicated Co-N-C significantly enhanced the generation of superoxide species, and accelerated hydroxyl radical generation for pollutant degradation. The electrochemical and surface composition analyses demonstrated the enhanced H2O2 activation and Fe(III)/Fe(II) recycling on the catalyst. Furthermore, in-situ Raman characterization with shell-isolated gold nanoparticles was employed to visualize the interfacial reactive intermediates and their time-resolved interaction. The accumulation of interfacial CoOOH* was confirmed when Co-N-C activated H2O2 alone, but it rapidly transformed into FeOOH* upon Fe(II) addition. Besides, the temporal variation of OOH* intermediates and the relative intensity of Co(III)-O and Co(IV)=O peaks depicted the dynamic interaction of reactive intermediates along the H2O2 consumption. With this basis, we proposed a mechanism of interfacial OOH* mediated Fe(II) regeneration, which overcame the kinetical limitation of Fe(II)/H2O2 system. Therefore, this study provided a primary effort to elucidate the overlooked role of interfacial CoOOH* in the Fenton-like processes, which may inspire the design of more efficient catalysts.

MoS2-based nanocomposites and aerogels for antibiotic pollutants removal from wastewater by photocatalytic degradation process: A review

Photocatalytic technologies based on molybdenum disulfide (MoS2) catalysts are effective, eco-friendly, and promising for antibiotic pollutants treatment. The technologies used by MoS2-based nanocomposites and aerogels for efficient degradation of antibiotics are reviewed in detail for the first time in this paper. The fundamental aspects of MoS2 were comprehensively scrutinized, encompassing crystal structure, optical properties, and photocatalytic principle. Then, the main synthesized methods and advantages/disadvantages for the preparation of MoS2-based nanocomposites and aerogels were systematically presented. Besides, a comprehensive overview of diverse MoS2-based nanocomposites and aerogels photo-degradation systems that enhanced the degradation of antibiotic pollutants were revealed. Meanwhile, the photo-degradation mechanism concentrated on the photoelectron transfer pathways and reactive oxygen species (ROS) were systematically evaluated. Finally, the challenges and perspectives for deeply development of MoS2-based nanocomposites and aerogels were discussed. This review may help researchers to deeply understand the research status of MoS2-based nanocomposites and aerogels for antibiotics removal, and makes clear the photo-degradation mechanism from photoelectron transfer pathways and ROS aspects of MoS2-based nanocomposites and aerogels.

Degradation of refractory organic matter in MBR effluent from treating landfill leachate by UV/PMS and UV/H2O2: a comparative study

This study applied ultraviolet/peroxymonosulfate (UV/PMS) and UV/hydrogen peroxide (UV/H2O2) processes to the advanced treatment of membrane bioreactor (MBR) effluent. The degradation efficiency of refractory organic matter and the reaction mechanisms of the two processes were systematically investigated. The results showed that the degradation efficiency of the UV/PMS processes was significantly lower than that of the UV/H2O2 process when the PMS concentration was significantly lower than the H2O2 concentration, e.g. the UV254 removals under optimal conditions were 72.92% and 82.21%, respectively. Additionally, the UV/PMS process could operate over a broader pH range. The degradation efficiency of the UV/PMS process was slightly increased by HCO3- and Cl- due to the activation of PMS, while in the UV/H2O2 process, HCO3- and Cl- depressed the degradation efficiency by competing with organic matter to react with reactive oxygen species (ROS). After the two processes, the aromaticity, humification, condensation degree, and molecular weight of refractory organic matter in the MBR effluent were considerably decreased. Fulvic- (HA) and humic-like substances (FA) were greatly degraded by the two processes. The UV/PMS had a superior degradation efficiency for macromolecular HA in the early stage of the reaction, and the UV/H2O2 could degrade HA to protein-like substances in the latter stage of the reaction. These differences between the two processes could be attributed to the dominance of different ROS, with SO4•- and HO• dominating in the UV/PMS, and HO• dominating in the UV/H2O2. The results of this study provide theoretical support for the application of MBR effluent treatment.Highlights Comparison on the MBR effluent treatment of UV/PMS and UV/H2O2 is studied.UV/PMS process can better destroy humic-like substances in the early reaction stage.Humic-like substances are transformed into protein-like compounds in UV/H2O2 process.UV/PMS and UV/PMS performs differently due to their different dominant ROS.

Persulfate catalyst synthesized with waterworks sludge for degrading Safranine T in the presence of boron

Energy conservation and emission reduction are the general trend of the present world. In this study, a catalyst of 3WSH based on the waste recycle of waterworks sludge (WS) and Chinese herbs was prepared using one-step calcination treatment and then characterized by SEM, XRD, XPS, FTIR and BET. The catalytic performance of 3WSHB for activating potassium persulfate (PDS) was evaluated through the degradation of Safranine T (ST) in the presence of boron powder (B). The effects of vital parameters on ST removal were systematically studied, including PDS concentration, 3WSHB dosage, initial solution pH, B dosage, temperature and coexisting cations. The highest efficiency of ST removal was up to 93.0% under the optimal condition with 1.85 mM of PDS, 0.3 g/L of 3WSHB, 0.35g/L of B, 7 of pH. EPR and free radical quenching experiments demonstrated that •OH was the dominant reactive oxygen species for ST degradation in the PDS/3WSHB/B system. Moreover, the intermediates determined by HPLC-MS indicated that the oxidization of benzene ring substituents in ST and a hydrogen abstraction by electron transfer might occur during ST degradation. The dissatisfied reuse performance of 3WSHB might be attributed to its low Fe content and simple reusing way. The results demonstrate the effectiveness of WS recycling and reuse in the field of pollutant remediation.

Remediation of environmentally persistent organic pollutants (POPs) by persulfates oxidation system (PS): A review

Over the past few years, persistent organic pollutants (POPs) exhibiting high ecotoxicity have been widely detected in the environment. Persulfate-oxidation hybrid system is one of the most widely used novel advanced oxidation techniques and is based on the persulfate generation of SO₄^-∙ and ∙OH from persulfate to degrade POPs. The overarching aim of this work is to provide a critical review of the variety of methods of peroxide activation (e.g., light activated persulfate, heat-activated persulfate, ultrasound-activated persulfate, electrochemically-activated persulfate, base-activated persulfate, transition metal activated persulfate, as well as Carbon based material activated persulfate). Specifically, through this article we make an attempt to provide the important characteristics and uses of main activated PS methods, as well as the prevailing mechanisms of activated PS to degrade organic pollutants in water. Finally, the advantages and disadvantages of each activation method are analyzed. This work clearly illustrates the benefits of different persulfate activation technologies, and explores persulfate activation in terms of Sustainable Development Goals, technical feasibility, toxicity assessment, and economics to facilitate the large-scale application of persulfate technologies. It also discusses how to choose the most suitable activation method to degrade different types of POPs, filling the research gap in this area and providing better guidance for future research and engineering applications of persulfates.

Degradation of petroleum pollutants in oil-based drilling cuttings using an Fe2+-based Fenton-like advanced oxidation processes

Oil-based drilling cuttings (OBDC) contain a large amount of total petroleum hydrocarbon (TPH) pollutants, which are hazardous to the environment. In this study, Fe²⁺-activating hydrogen peroxide (Fe²⁺/H₂O₂), peroxymonosulfate (Fe²⁺/PMS), and peroxydisulfate (Fe²⁺/PDS) advanced oxidation processes (AOPs) were used to treat OBDC due to the difference in the degradation capacity of TPH caused by the type of free radical generated and effective activation conditions observed for the different oxidants studied. The results showed that the oxidant concentration, Fe²⁺ dosage, and reaction time in the three AOPs were greatly positively correlated with the TPH removal rate in a certain range. The initial pH value had a significant effect on the Fe²⁺/H₂O₂ process, and its TPH removal rate was negatively correlated in the pH range from 3 to 11. However, the Fe²⁺/PMS and Fe²⁺/PDS processes only displayed lower TPH removal rates under neutral conditions and tolerated a wider range of pH conditions. The optimal TPH removal rates observed for the Fe²⁺/H₂O₂, Fe²⁺/PMS, and Fe²⁺/PDS processes were 45.04%, 42.75%, and 44.95%, respectively. Fourier transform infrared spectrometer and gas chromatography-mass spectrometer analysis showed that the alkanes in OBDC could be effectively removed using the three processes studied, and their degradation ability toward straight-chain alkanes was in the order of Fe²⁺/PMS > Fe²⁺/PDS > Fe²⁺/H₂O₂, among which Fe²⁺/PMS exhibited the optimal removal effect for aromatic hydrocarbons. Scanning electron microscope, energy dispersive spectroscopy, and X-ray diffraction results showed no significant changes in the elemental and mineral composition of OBDC before and after treatment. Therefore, this study provided a theoretical reference for the effective degradation of TPH pollutants in OBDC.

Catalytic activation of peroxydisulfate by secondary mineral derived self-modified iron-based composite for florfenicol degradation: Performance and mechanism

The advanced oxidation processes (AOPs) driven by iron-based materials are the highly efficient technology for refractory organic pollutants treatment. In this work, self-modified iron-based catalysts were prepared using secondary mineral as the precursor by one-step pyrolysis process without additional dopants. The prepared catalysts exhibited excellent performance in catalytic degradation of florfenicol (FF), especially C-AJ, which was derived from ammoniojarosite [(NH₄, H₃O)Fe₃(OH)₆(SO₄)₂], activated PDS to degrade 93% FF with initial concentration of 50 mg/L. Quenching tests and electron paramagnetic resonance (ESR) studies showed that SO₄^•-, ^•OH, and ^•O₂^- were the main reactive species for FF degradation and their contribution degree was SO₄^•- > ^•OH > •O₂^-. The Fe⁰ and the cycle of Fe(II)/Fe(III) both contributed to the PDS activation, and the reduction of Fe(III) to Fe(II) was accelerated by S^2- on the catalyst surface. In addition, Fe₃O₄ on the C-AJ indirectly catalyzes PDS by promoting electron transfer. The effects of catalyst dosage, PDS concentration, pH, inorganic anions, and real aqueous matrices on FF degradation, TOC analysis, and cycling test were investigated. The results showed that iron-based catalysts have superior environmental durability due to their excellent catalytic properties in the real aqueous matrices with common inorganic anions and pH 3-9 and its steady catalytic capacity with multiple cycles. Overall, this study sheds new light on the rational design of self-modified iron-based composite and develops low-cost technology toward remediation of FF-contaminated wastewater.

Preparation and performance of Novel Ni-doped Iron oxychloride with High singlet oxygen generation

Singlet oxygen with lower oxide electrode potential but higher selective oxidation ability towards specific organic contaminants had been paid great attention. An efficient system with high singlet oxygen generation (over...