Ultrafast short-range catalytic pathway modified peroxymonosulfate activation over CuO with surface oxygen defects for tetracycline hydrochloride degradation

LED illumination-assisted activation of peroxydisulfate by heterogeneous Cu2S under alkaline condition for efficient organic pollutants removal

The copper-based materials were considered as promising catalysts for the activation of peroxydisulfate (PDS), but the study on the Cu2S-activated PDS under LED illumination and alkaline condition was little reported. In this work, Cu2S, a simple and readily available heterogeneous catalyst, was employed to enhance the activation of PDS under alkaline condition through LED illumination. The results indicated that under LED illumination, the degradation rate of tetracycline (TC) during the first 15 min was 3.55 times higher than that of the darkness. A series of important influencing factors were optimized, including anions, humic acid and complex water matrices. The results showed that the Cu2S/PDS/LED system exhibited excellent adaptability. Besides, the Cu2S maintained a good stability. The quenching experiments and electron spin resonance analysis demonstrated that the electron transfer and singlet oxygen were two primary pathways for the degradation of TC, and also other species such as sulfate and hydroxyl radicals played important roles. Furthermore, X-ray photoelectron spectroscopy characterization and a series of experiments confirmed that the Cu+ was the primary catalytic active sites, while the reductive sulfur species could directly activate PDS and accelerate the circulation of Cu2+/Cu+. The toxicity test proved that the toxicity of TC was decreased after the degradation. This study not only highlighted the potential of the Cu2S/PDS/LED system for efficient TC degradation under alkaline condition but also provided new insight for the development of Cu-based catalytic technology.

Enhanced peroxymonosulfate activation for emerging contaminant degradation via defect-engineered interfacial electric field in FeNC

Peroxymonosulfate (PMS) activation technology has important application value in treating emerging contaminant (ECs), but it still faces challenges in achieving efficient electron transfer and metal valence cycling. In this study, the interfacial electric field characteristics of FeNC catalysts were adjusted by introducing NC defects to affect the electron transfer process, thereby enhancing the catalytic performance of PMS. It is found that in the FeNC structure, the shift of the charge generates an interfacial electric field, which can promote the directional transfer of electrons. Through quantitative structure-activity relationship (QSAR) analysis, it was confirmed that the defect played a decisive role in regulating the interfacial electric field and improving the catalytic reaction efficiency. The interfacial electric field-mediated superexchange interaction realizes the electron donor effect of organic pollutants and the effective electron transfer between the Fe site, accelerates the electron cycling of the Fe site, and realizes the rapid and stable catalysis of PMS. The increase of the occupancy state distribution of d orbitals near the Fermi level provides favorable conditions for electron transitions and catalytic activation of PMS. ECs can be converted into environmentally friendly, non-toxic and harmless substances through. This defect-controlled interface electric field strategy realizes rapid electron directional transfer, which provides a new solution for improving the catalytic efficiency of PMS and the safe treatment of ECs in water.

In Situ Construction of CdS/g-C3N4 Heterojunctions in Spent Thiolation@Wood-Aerogel for Efficient Excitation Peroxymonosulfate to Degradation Tetracycline

Pollutant treatment, hazardous solid waste conversion, and biomass resource utilization are significant topics in environmental pollution control, and simultaneously achieving them is challenging. Herein, we developed a "from waste absorbent to effective photocatalyst" upcycle strategy for nontoxic conversion of Cd(II) adsorbed on thiolation@wood-aerogel (TWA) into CdS/g-C3N4 heterojunctions through the in situ chemical deposition high-temperature carbonization combined conversion method to overcome the above problems simultaneously. We used Schiff base reaction to graft l-cysteine into dialdehyde@wood-aerogel to prepare TWA with a high Cd(II) adsorption capacity (600 mg/L, 294.66 mg/g). Subsequently, the spent Cd(II)-loaded-TWA was used as a substrate for in situ construction of Cd(II) into CdS/g-C3N4 heterojunction for activating peroxymonosulfate (PMS) under simulated sunlight [simulated solar light (SSL)], achieving efficient tetracycline (TC) degradation (20 mg/L, 95.32%). The Langmuir and pseudo-second-order models indicate single-layer chemical adsorption of Cd(II) on the TWA adsorption process. In the PMS/SSL system, CdS/g-C3N4@TWA efficiently and rapidly degraded TC via an adsorption-photocatalytic synergistic degradation mechanism. The used CdS/g-C3N4@TWA has a good biocompatibility. This study proposed design and preparation of a new type of wood aerogel absorbent and provided a novel upcycling strategy for innovative use of the spent waste adsorbent.

Peroxymonosulfate activation by walnut shell activated carbon supported nano zero-valent iron for the degradation of tetracycline: Performance, degradation pathway and mechanism

In this study, activated carbon (WS-AC) was prepared from walnut shell. Nano-zero-valent iron (nZVI) was loaded on walnut shell activated carbon by liquid phase reduction method and used as catalyst (WS-AC/nZVI) to activate peroxymonosulfate (PMS) to efficiently degrade tetracycline (TC) in solution. The composite material with a mass ratio of WS-AC to nZVI of 1:1 has the highest catalytic performance for activating PMS to degrade TC. The results showed that under the conditions of TC concentration of 100 ppm, PMS dosage of 0.2 mM and WS-AC/nZVI dosage of 0.1 g/L, the removal efficiency of TC could reach 81%. Based on quenching experiments and electron spin resonance (EPR), it was verified that •OH, SO4•- and 1O2 bound on the catalyst surface were the main reactive oxygen species during the reaction. The intermediate products of TC were identified by liquid chromatography-mass spectrometry (HPLC-MS) and DFT calculation, and the possible degradation pathway of TC was proposed. The catalyst still maintained high removal efficiency of TC after four cycles of experiments, and the minimal iron loss on the surface of the catalyst indicated that it had good stability. The efficient and stable WS-AC/nZVI activated PMS showed great potential in the degradation of antibiotics.

Antibiotic removal from synthetic and real aqueous matrices by peroxymonosulfate-based advanced oxidation processes. A review of recent development

The widespread use of antibiotics for the treatment of bacteriological diseases causes their accumulation at low concentrations in natural waters. This gives health risks to animals and humans since it can increase the damage of the beneficial bacteria, the control of infectious diseases, and the resistance to bacterial infection. Potent oxidation methods are required to remove these pollutants from water because of their inefficient abatement in municipal wastewater treatment plants. Over the last three years in the period 2021-September 2023, powerful peroxymonosulfate (PMS)-based advanced oxidation processes (AOPs) have been developed to guaranty the effective removal of antibiotics in synthetic and real waters and wastewater. This review presents a comprehensive analysis of the different procedures proposed to activate PMS-producing strong oxidizing agents like sulfate radical (SO4•-), hydroxyl radical (•OH, radical superoxide ion (O2•-), and non-radical singlet oxygen (1O2) at different proportions depending on the experimental conditions. Iron, non-iron transition metals, biochar, and carbonaceous materials catalytic, UVC, photocatalytic, thermal, electrochemical, and other processes for PMS activation are summarized. The fundamentals and characteristics of these procedures are detailed remarking on their oxidation power to remove antibiotics, the influence of operating variables, the production and detection of radical and non-radical oxidizing agents, the effect of added inorganic anions, natural organic matter, and aqueous matrix, and the identification of by-products formed. Finally, the theoretical and experimental analysis of the change of solution toxicity during the PMS-based AOPs are described.

Heteroatom-modulated NiCo2O4 apparent energy activation of PMS for tetracycline removal: Mechanism and toxicity analysis

Heteroatom doping to reconfigure the electronic structure of heterogeneous catalysts is expected to lead to the development of advanced oxidation water purification materials with superior performance and greater stability. Herein, a series of catalysts with different elemental doping was developed by a simple and environmentally friendly one-step self-propagating combustion method to remove Tetracycline (TC). After S-doping, the normalized kinetic constant of TC was significantly increased from 30.49 to 159.41 min-1M-1 within 30 min, which is even higher than most recent heterogeneous catalysts. The prepared S-doped NiCo2O4 (NCO-S) exhibits an extremely promising catalytic performance for oxidation (92.8 %) and mineralization (65.9 %) of TC in a wide pH range (3-11). The resistance to interference is excellent for inorganic ions and even in real water samples. Quenching experiments, electron paramagnetic resonance (EPR), and electrochemical analyses demonstrated that the non-radical oxidation pathway, including electron transfer and 1O2, dominated the degradation process after S doping. It is speculated that possible intermediates and toxicological studies are discussed, finding that the overall degradation process is moving towards low toxicity to reveal prospects for large-scale applications. This work not only provides a way to remove TC, but may also inspire the design of more efficient and stable materials for water treatment and other applications.

Generation and identification of 1O2 in catalysts/peroxymonosulfate systems for water purification

Catalysts for peroxymonosulfate (PMS) activation are appealing in the purification of organic wastewater. Singlet oxygen (1O2) is widely recognized as a crucial reactive species for degrading organic contaminants in catalysts/PMS systems due to its adamant resistance to inorganic anions, high selectivity, and broad pH applicability. With the rapid growth of studies on 1O2 in catalysts/PMS systems, it becomes necessary to provide a comprehensive review of its current state. This review highlights recent advancements concerning 1O2 in catalysts/PMS systems, with a primary focus on generation pathways and identification methods. The generation pathways of 1O2 are summarized based on whether (distinguished by the geometric structures of metal species) or not (distinguished by the active sites) the metal element is included in the catalysts. Furthermore, this review thoroughly discusses the influence of metal valence states and metal species with different geometric structures on 1O2 generation. Various potential strategies are explored to regulate the generation of 1O2 from the perspective of catalyst design. Identification methods of 1O2 primarily include electron paramagnetic resonance (EPR), quenching experiments, reaction in D2O solution, and chemical probe tests in catalysts/PMS systems. The principles and applications of these methods are presented comprehensively along with their applicability, possible disagreements, and corresponding solutions. Besides, an identifying procedure on the combination of main identification methods is provided to evaluate the role of 1O2 in catalysts/PMS systems. Lastly, several perspectives for further studies are proposed to facilitate developments of 1O2 in catalysts/PMS systems.