Activation of peroxymonosulfate (PMS) by iron species represents an efficient advanced oxidation route for the degradation of contaminants in water, being Fe(III) reduction a crucial stage. In this work, the role of protocatechuic acid (pCtchA) in the Fe(II)/Fe(III)/PMS system was investigated through a mechanistic model constructed from a comprehensive set of elementary reactions describing radical and nonradical pathways. Model simulations were validated with batch reactor data and accurately reproduced the effects of iron (2.0 & times; 10-6-2.0 & times; 10-5 M) and PMS (4.1 & times; 10-5-2.45 & times; 10-3 M) concentrations, temperature (10-50 degrees C), and pH (2-7). The results confirm that Fe(III) reduction to Fe(II) is the rate-determining step. Optimal degradation occurs near pH 3.5, where Fe(III)-pCtchA monocomplexes predominate. Proton concentration is inversely proportional to the efficacy of the process in the acidic region. The apparent activation energy for Fe(III) reduction is approximately 36 kJ mol-1. This study provides a quantitative kinetic framework for the Fe(II)/Fe(III)/PMS system accounting for the effect of essential parameters such as pH, reagent concentrations, and temperature, demonstrating its potential as a sustainable catalytic process in aqueous media.
The interaction of ozone (O-3) molecules with MoS2 monolayers modified by different Cu-n (n = 1-3) clusters were investigated using density functional theory (DFT). The computational results demonstrated that Cu-n (n = 1-3) clusters modified substrates can achieve stable and effective adsorption toward O-3 molecules. Correspondingly, the calculated adsorption energies of O-3 on Cu-1-MoS2, Cu-2-MoS2 and Cu-3-MoS2 are -2.883 eV, -2.371 eV and -2.781 eV respectively, revealing distinct differences in adsorption strength among different modification systems. The absolute values of the adsorption energies of O-3 on the three adsorption structures are all very large. The Cu-1-MoS2 system has the largest adsorption energy for O-3, exhibiting the strongest interaction with O-3 molecules and an extremely strong ability to capture and fix O-3, the adsorption energy of Cu-2-MoS2 is the lowest among the three configurations, showing relatively moderate adsorption for O-3 and moderate interface interaction strength, the adsorption energy of Cu-3-MoS2 is between that of Cu-1 and Cu-2, with intermediate adsorption strength and charge transfer, providing O-3 capture ability better than Cu-2 but weaker than Cu-1. These distinct adsorption energy differences reveal that Cu cluster modified MoS2 materials possess favorable adsorption performance toward O-3. Through comprehensive first-principles calculations, this study fully clarifies the interaction mechanism between O-3 and Cu-n (n = 1-3) clusters modified MoS2, proving that such composite structures are highly suitable for practical O-3 sensing applications. The research findings not only deepen the fundamental understanding of cluster modification regulation mechanism, but also provide reliable theoretical basis and constructive design ideas for developing high-efficiency two-dimensional gas sensing materials and promoting the practical development of related functional sensing devices.
Ti/SnO2-Sb-Ni (Ti/NATO) is an effective anode for electrochemical ozone production (EOP), yet its limited service life hinders practical use. TiO2 nanotube arrays (TNTAs) with tunable inner diameter, outer diameter, and length were constructed on Ti substrates as an interlayer, and their geometric effects on the stability, electrochemical behavior, and ozone generation of Ti/NATO electrodes were systematically evaluated. Standardized multiple linear regression and correlation heatmaps quantified the relationships between TNTA morphology and performance. The TNTA interlayer enhanced coating - substrate adhesion, mitigated delamination and substrate passivation, and improved durability. Among the morphological parameters, nanotube length emerged as the primary structural determinant of the electrode performance. The optimized Ti/30 V-2 h TNTAs/SnO2-Sb-Ni(30-2/NATO) electrode exhibited a 6.62 h accelerated lifetime (3.74-fold higher than without interlayer), increased dissolved ozone concentration to 4.73 mg L-1 (+73%), and reduced specific energy consumption by 41%. Electrochemical analyses showed enlarged electrochemically active surface area, decreased charge-transfer resistance, and a positive shift in oxygen evolution potential (OEP), effectively suppressing the competing oxygen evolution reaction. This study elucidates how tailoring the TNTA interlayer morphology enhances both ozone generation performance and service life of Ti/NATO electrodes, providing theoretical guidance for the design of high-efficiency, durable electrochemical ozone anodes.
The objectives of this study were to assess the effect of ozone on the control of S. zeamais eggs in corn seeds and to evaluate potential impacts on physiological quality following ozonation and during storage. Ozonation was carried out with an inlet concentration of 2 mg L-1 and a flow rate of 2.0 m3 min-1 t-1. Saturation occurred after 32.2 min, reaching a concentration of 1.5 mg L-1. Insect emergence (30 to 50 days) and seed quality (0 to 180 days) were evaluated. Ozone effectively controlled the eggs after 24 h of treatment. In non-ozonated seeds, an average of 11.5 +/- 6.8 insects emerged, whereas in treatments lasting 6 h or more, the average was <= 0.5 insects. Germination remained above 85% across all treatments, with no significant changes observed in the regression for mean germination time or germination speed. Electrical conductivity increased with longer ozonation and storage durations, ranging from 19.1 & micro;S cm-1 g-1 in the control to 21.9 & micro;S cm-1 g-1 after 24 h. Ozone treatment at 2.0 mg L-1 and a flow rate of 2.0 m3 min-1 t-1 effectively controls S. zeamais eggs, particularly with 24 h of exposure, without compromising the physiological quality of the seeds during storage.
Dimethyl sulfide (DMS) is a representative reduced sulfur compound that is difficult to oxidize and remove, particularly under the high-humidity conditions commonly encountered in waste-treatment and biomass power plants. In this study, a practical strategy for DMS removal under high-humidity conditions was investigated by combining ozone oxidation with a low-cost iodate-impregnated activated carbon catalyst with moderate catalyst heating. Ozone was generated using a xenon excimer lamp, enabling a compact system design without the need for a pressure-swing adsorption oxygen generator and thereby making the system suitable for small-scale and distributed applications. The DMS removal performance was evaluated using a dynamic adsorption method under relative humidity (RH) conditions of 45% and 90%. At 25 degrees C and 45% RH, the treatment capacity and reaction rate constant were 15 wt% and 6.9 s(-1), respectively, whereas these values decreased to 1.5 wt% and 4.9 s(-1) at 25 degrees C and 90% RH, indicating that water vapor significantly interfered with DMS treatment through preferential adsorption. However, when the catalyst temperature was increased by 10 degrees C (from 25 degrees C to 35 degrees C) under high-humidity conditions, the treatment capacity and reaction rate constant improved to 2.8 wt% and 5.8 s(-1), respectively. This enhancement was attributed to the asymmetric adsorption behavior of DMS and water vapor, whereby moderate heating reduced water adsorption and restored sites available for DMS adsorption.
