Degradation of norfloxacin by calcite activating peroxymonosulfate: Performance and mechanism

Efficient elimination of carbamazepine using polyacrylonitrile-supported pyridine bridged iron phthalocyanine nanofibers by activating peroxymonosulfate in dark condition

The monoaminotrinitro iron phthalocyanine (FeMATNPc) is used to connect with isonicotinic acid (INA) for amide bonding and axial coordination to synthetic a unique catalyst FeMATNPc-INA, which is loaded in polyacrylonitrile (PAN) nanofibers by electrospinning. The introduction of INA destroys the π-π conjugated stack structure in phthalocyanine molecules and exposes more active sites. The FeMATNPc-INA structure is characterized by X-ray photoelectron spectroscopy and UV-visible absorption spectrum, and the FeMATNPc-INA/PAN structure is characterized by Fourier transform infrared spectroscopy and X-ray diffraction. The FeMATNPc-INA/PAN can effectively activate peroxymonosulfate (PMS) to eliminate carbamazepine (CBZ) within 40 minutes (PMS 1.5 mmol/L) in the dark. The effects of catalyst dosage, PMS concentration, pH and inorganic anion on the degradation of CBZ are investigated. It has been confirmed by electron paramagnetic resonance, gas chromatography-mass spectroscopy and free radical capture experiments that the catalytic system is degraded by •OH, SO4•- and Fe (IV) = O are the major active species, the singlet oxygen (1O2) is the secondary active species. The degradation process of CBZ is analyzed by ultra-high performance liquid chromatography-mass spectrometry and the aromatic compounds have been degraded to small molecular acids.

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.

Tetracycline inhibits the nitrogen fixation ability of soybean (Glycine max (L.) Merr.) nodules in black soil by altering the root and rhizosphere bacterial communities

Tetracycline is a widely used antibiotic and may thus also be an environmental contaminant with an influence on plant growth. The aim of this study was to investigate the inhibition mechanisms of tetracycline in relation to soybean growth and ecological networks in the roots and rhizosphere. To this end, we conducted a pot experiment in which soybean seedlings were grown in soil treated with 0, 10, or 25 mg/kg tetracycline. The effects of tetracycline pollution on growth, productivity, oxidative stress, and nitrogenase activity were evaluated. We further identified the changes in microbial taxa composition and structure at the genus and species levels by sequencing the 16S rRNA gene region. The results showed that tetracycline activates the antioxidant defense system in soybeans, which reduces the abundance of Bradyrhizobiaceae, inhibits the nitrogen-fixing ability, and decreases the nitrogen content in the root system. Tetracycline was also found to suppress the formation of the rhizospheric environment and decrease the complexity and stability of bacterial networks. Beta diversity analysis showed that the community structure of the root was markedly changed by the addition of tetracycline, which predominantly affected stochastic processes. These findings demonstrate that the influence of tetracycline on soybean roots could be attributed to the decreased stability of the bacterial community structure, which limits the number of rhizobium nodules and inhibits the nitrogen-fixing capacity. This exploration of the inhibitory mechanisms of tetracycline in relation to soybean root development emphasises the potential risks of tetracycline pollution to plant growth in an agricultural setting. Furthermore, this study provides a theoretical foundation from which to improve our understanding of the physiological toxicity of antibiotics in farmland.

The pH-sensitive transformation of birnessite and its effect on the fate of norfloxacin

Birnessite plays a crucial role in regulating the fate of contaminants in soil, which is affected by the crystal structure of birnessite. In this study, the transformation of triclinic birnessite to hexagonal birnessite was examined at various pH values, and their reactivity towards norfloxacin was investigated. The findings indicate that the conversion from triclinic birnessite to hexagonal birnessite occurs under pH conditions lower than 7. The lower of the solution pH where the birnessite formed, the higher the surface reactivity. Throughout the transformation process, the migration of Mn3+ and the increased interlayer protons generated more reactive oxygen species, which enhanced the surface reactivity towards norfloxacin. Specifically, at a conversion pH of 1, the norfloxacin removal rate significantly increases from 14% to 97% compared to triclinic birnessite. The mechanism of norfloxacin removal by triclinic and hexagonal birnessite is illustrated. These findings provide valuable insights into the dynamic transformation of birnessites in aqueous environments with varying pH values and their impact on norfloxacin removal.

Fe3N nanoparticles embedded in N-doped porous magnetic graphene for peroxymonosulfate activation: Radical and nonradical mechanism

The persistence of pharmaceutical and personal care products (PPCPs) such as norfloxacin (NFX) poses a serious threat to the water environment, and the development of efficient and cost-effective advanced oxidation catalysts is an important step toward resolving this issue. Herein, Fe and N co-doped graphene (FeNGO) was synthesized from graphene oxide (GO), urea, and iron salt via simple impregnation pyrolysis, and applied for activating peroxymonosulfate (PMS) to degrade NFX. FeNGO possessed a two-dimensional porous sheet structure and was rich in defects, nitrogen species, and active sites. Compared with the control catalyst doped with N or Fe alone, FeNGO/PMS system showed the best degradation performance with 97.7% removal of NFX after 30 min, the rate constant was 7.1 and 1.7 times than that for NGO and FeGO, respectively. Fe₃N was the main active site of FeNGO, and it is confirmed that singlet oxygen (¹O₂) and superoxide radical (O₂^•-) were the primary oxidation active species (ROS) during NFX degradation. The formation of ¹O₂ came from the transformation of O₂^•- and PMS decomposition. FeNGO showed strong pH adaptability, and also exhibited stale degradation performance in saliferous water matrices. It is believed that this work will offer theoretical and practical guidance for PMS activation by non-radical pathways.

Monopersulfate in water treatment: Kinetics

The kinetics of monopersulfate based systems in the elimination of potential harmful contaminants has been assessed from a theoretical point of view. A detailed reaction mechanism sustained in the generation of radicals (mainly hydroxyl and sulfate), propagation and termination stages has been proposed. The system of first order differential equations derived has numerically been solved. The effect of main influencing parameters such as contaminant and peroxymonosulfate initial concentrations, intermediate generation, presence of organic matter, role played by anions, has been theoretically obtained. Discussion of simulated results has been accomplished by comparison with experimental data found in the literature. At the sight of the theoretical and empirical data, use of simplistic pseudo first order kinetics is discouraged. Despite considering a significant number of elemental reactions, modelling of the system reveals that a high fraction of them can be neglected due to their insignificant role played in the mechanism. The entire mechanism has been tested when peroxymonosulfate has been activated by UV radiation, although results can be fairly extrapolated to other activation strategies. Finally, a generic model capable of accounting for the effect of a diversity of parameters is proposed. No theoretical background is behind the model, however the generic model clearly improves the results obtained by simple first order kinetics.

The removal performance and mechanisms of tetracycline over Mn-rich limonite

Naturally occurring Mn-rich limonite mainly composed of goethite and manganese oxides was used to remove tetracycline (TC) from the aqueous solution. The effects of dosage, initial solution pH, temperature, and coexisting anions on TC removal were investigated. Results showed that 95% of TC (30.0 mg·L^-1) was removed in a wide pH range of 3.0-9.0 by limonite with high specific surface area (145.0 m²·g^-1) and mesoporous structure. The presence of Cl^-, NO₃^-, and SO₄^2- in the studied concentration range did not influence TC removal efficiency significantly, while PO₄^3- inhibited the adsorption of TC over limonite due to the competition with TC for active sites. Integrated with the FT-IR analysis, electrostatic interaction and complexation were proved to be the adsorption mechanisms of TC by limonite. The quenching experiments and ESR analysis revealed that singlet oxygen (¹O₂) also was involved in TC degradation. In addition, limonite displayed an efficient recycling performance and stability after four cycles. This study revealed that the Mn-rich limonite was a promising adsorbent for TC removal from aqueous solutions and promoted the application of natural mineral material in the environmental field.