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In this work, PCN-224(Fe) porphyrin-based metal–organic frameworks and a Poly(ionic liquids) (PILs) were used to prepare PCN-224(Fe)@PIL(Cl−) composite films by UV polymerisation. The structure, morphology, chemical composition, and electrochemical properties of the as-prepared composite film were investigated. PCN-224(Fe) was coated with a kind of P(1-vinylpyridinium chloride as monomer) on the outside to improve the electron transfer efficiency, while an electrochemical system was employed to catalysis the persulfate (PS) decomposition for the efficient degradation of tetracycline (TC). Because of the cathodic reduction reaction, the continuous redox cycle between Fe3+/Fe2+ was facilitated, which enhanced the degradation activity of persulfate on tetracycline. The PCN-224(Fe)@PIL(Cl−) composite demonstrated a superior electrocatalytic degradation efficiency of 95.8% in just 40 min for the TC model pollutant, surpassing the 63.3% efficiency of pure PCN-224(Fe) within 60 min. This work shows a successful example of using PILs to enhance catalytic degradation activity and points out a direction of preparation of catalysts for activating persulfate (PS). [ABSTRACT FROM AUTHOR]

Understanding the near-ground vertical and temporal photochemical O 3 formation mechanism is important to mitigate O 3 pollution. Here, we measured the vertical profiles of O 3 and its precursors at six different heights, ranging from 5 to 335 m, using a newly built vertical observation system in the Pearl River Delta (PRD) region of China. The net photochemical ozone production rate (P (O 3) net) and O 3 formation sensitivities at various heights were diagnosed using an observation-based model coupled with the Master Chemical Mechanism (MCM v3.3.1). Moreover, to assess model performance and identify the causative factors behind O 3 pollution episodes, the P (O 3) net was measured at 5 m above ground level with a custom-built detection system. In total, three O 3 pollution episodes and two non-episodes were captured. The identified O 3 pollution episodes were found to be jointly influenced by both photochemical production and physical transport, with local photochemical reactions playing a major role. The high index of agreement (IOA) calculated by comparing the modelled and measured P (O 3) net values indicated the rationality of investigating the vertical and temporal variability in O 3 formation mechanisms using model results. However, the measured P (O 3) net values were generally higher than the modelled P (O 3) net values, particularly under high-NO x conditions, which may indicate a potential underestimation of total RO 2 by the model. Throughout the measurement period, the contribution of different reaction pathways to O 3 production remained consistent across various heights, with HO 2 + NO as the major O 3 production pathway, followed by RO 2 + NO. We observed that P (O 3) net decreased with an increase in measurement height, which was primarily attributed to the reduction in O 3 precursors, such as oxygenated volatile organic compounds (OVOCs) and non-methane hydrocarbons (NMHCs). The O 3 formation regimes were similar at different heights during both episodes and non-episodes, either being located in the VOC-sensitive regime or in the transition regime that is more sensitive to VOCs. Diurnally, photochemical O 3 formation typically remained in the VOC-sensitive regime during the morning and noon, but it transitioned to the transition regime and was more sensitive to VOCs in the afternoon at around 16:00 LT (local time). Vertical and temporal photochemical O 3 formation is most sensitive to OVOCs, suggesting that targeting specific VOCs for control measures is more practical and feasible at the observation site. The vertical temporal analysis of O 3 formation mechanisms near the ground surface in this study provides critical foundational knowledge that can be used to formulate effective short-term emergency and long-term control strategies to combat O 3 pollution in the PRD region of China. [ABSTRACT FROM AUTHOR]

The In2.77S4/In-MOFs Z-scheme heterojunction composite photocatalysts were successfully synthesized via an insitu hydrothermal growth method. The chemical structure, morphology, optical properties, and photogenerated carriers transfer behavior of the as-prepared In2.77S4/In-MOFs composites were characterized in details. The In2.77S4/In-MOFs (10 wt%) composite showed the optimal photocatalytic degradation efficiency of 95.9% in 90 min for the tetracycline (TC) model pollutant, which was significantly higher than that of pure In2.77S4 (75.1%) and In-MOFs (9.7%). The X-ray photoelectron spectrometer (XPS), photoelectrochemical, and electron paramagnetic resonance (EPR) technique were carried out to illuminate the photocatalytic degradation mechanism of In2.77S4/In-MOFs (10 wt%) for TC, which showed that the Z-scheme heterojunction structure of In2.77S4/In-MOFs (10 wt%) could reinforced the light harvesting capacity and promote the photogenerated carrier migration under visible light irradiation. Furthermore, the photogenerated holes play a major role during the photocatalytic degradation reaction. Finally, this work maybe offers an effective method for the designing In2.77S4-based Z-scheme heterojunctions to facilitate the charge carrier transfer in heterogeneous catalysts. [ABSTRACT FROM AUTHOR]

Volatile chemical products (VCPs) have become an important source of reactive organic gases (ROGs) in urban areas worldwide. Industrial activities can also utilize a large number of VCPs and emit many organic gases into the atmosphere. Due to multiple sampling and measurement challenges, only a subset of ROG species is usually measured for many industrial VCP sources. This study aims to investigate the emissions of ROGs from five industrial VCP sources in the Pearl River Delta (PRD) region of China, including the shoemaking, plastic surface coating, furniture coating, printing, and ship coating industries. A more comprehensive speciation of ROG emissions from these industrial VCP sources was developed by the combination of proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS) and the gas chromatography–mass spectrometer/flame ionization detector (GC–MS/FID). Our study identified oxygenated ROG species (OVOCs) as representative ROGs emitted from these sources, which are highly related to specific chemicals used during industrial activities. Moreover, mass spectra similarity analysis revealed significant dissimilarities among the ROG emissions from industrial activities, indicating substantial variations between different industrial VCP sources. Except for the ship coating industry utilizing solvent-borne coatings, the proportions of OVOCs range from 67 % to 96 % in total ROG emissions and 72 % to 97 % in total OH reactivity (OHR) for different industrial sources, while the corresponding contributions of OVOCs in the ship coating industry are only 16 ± 3.5 % and 15 ± 3.6 %. The industrial VCP sources associated with solvent-borne coatings exhibited a higher ozone formation potential (OFP), reaching as high as 5.5 and 2.7 g O 3 g -1 ROGs for the ship coating and furniture coating industries, primarily due to contributions from aromatics. We find that a few species can contribute the majority of the ROG emissions and also their OHR and OFP from various industrial VCP sources. Our results suggest that ROG treatment devices may have limited effectiveness for all ROGs, with treatment efficiencies ranging from - 12 % to 68 %. Furthermore, we found that ambient measurements in industrial areas have been significantly impacted by industrial VCP sources, and ROG pairs (e.g., methyl ethyl ketone (MEK) / C 8 aromatics ratio) can be utilized as reliable evidence by using high-time-resolution ROG measurements from PTR-ToF-MS. Our study demonstrated the importance of measuring a large number of ROGs using PTR-ToF-MS for characterizing ROG emissions from industrial VCP sources. [ABSTRACT FROM AUTHOR]

Formic acid is the most abundant organic acid in the troposphere and has significant environmental and climatic impacts. Isocyanic acid poses severe threats to human health and could be formed through the degradation of formic acid. However, the lack of vertical observation information has strongly limited the understanding of their sources, particularly in urban regions with complex pollutant emissions. To address this issue, we assessed the impact of long tubes on the measurement uncertainties of formic and isocyanic acids and found that the tubing impact was negligible. Then, we conducted continuous (27 d) vertical gradient measurements (five heights between 5–320 m) of formic and isocyanic acids using long tubes based on a tall tower in Beijing, China, in the summer of 2021. Results show that the respective mean mixing ratios of formic and isocyanic acids were 1.3 ± 1.3 ppbv and 0.28 ± 0.16 ppbv at 5 m and were 2.1 ± 1.9 ppbv and 0.43 ± 0.21 ppbv at 320 m during the campaign. The mixing ratios of formic and isocyanic acids were substantially enhanced in the daytime and correlated with the diurnal change of ozone. Upon sunrise, the mixing ratios of formic and isocyanic acids at different heights simultaneously increased, even in the residual layer. In addition, positive vertical gradients were observed for formic and isocyanic acids throughout the day. The positive vertical gradients of formic and isocyanic acids in the daytime imply the enhancement of their secondary formation in urban regions aloft, predominantly due to the enhancements of oxygenated volatile organic compounds. Furthermore, the afternoon peaks and positive vertical gradients of formic and isocyanic acids in the nighttime also indicate their minor contributions from primary emissions from ground-level sources. The formation pathway of isocyanic acid through HCOOH– CH3NO –HNCO was enhanced with height but only accounted for a tiny fraction of its ambient abundance. The abundance and source contributions of formic and isocyanic acids in the atmospheric boundary layer may be highly underestimated when being derived from their ground-level measurements. With the aid of numerical modeling techniques, future studies could further identify key precursors that drive the rapid formation of formic and isocyanic acids and quantitatively assess the impacts of the enhanced formation of the two acids aloft on their budgets at ground level. [ABSTRACT FROM AUTHOR]

Understanding the near-ground vertical and temporal photochemical O3 formation mechanism is important to mitigate the O3 pollution. Here, we measured the vertical profiles of O3 and its precursors at six different heights from 5-335 m using a newly built vertical observation system in Pearl River Delta (PRD) region, China. The net photochemical ozone production rate (P (O3)net) and O3 formation sensitivities at various heights were diagnosed using an observation-based model coupled with the Master Chemical Mechanism (MCM v3.3.1). Moreover, for the assessment of model performance and the causative factors behind O3 pollution episodes, the net photochemical ozone production rate (P (O3)net) was measured at 5 m ground level utilizing a custom-built detection system. In total three O3 pollution episodes and two non-episodes were captured. The identified O3 pollution episodes were found to be jointly influenced by both photochemical production and physical transport, with local photochemical reactions play a dominate role. The high index of agreement (IOA) calculated from comparing the modelled and measured P (O3)net values indicated the rationality to investigate the vertical and temporal variability of O3 formation mechanism using modelling results. However, the measured P (O3)net values were generally higher than the modelled P (O3)net values, particularly under high NOx conditions, which may indicate a potential underestimation of total RO2 by the model. Throughout the measurement period, the contribution of different reaction pathways to O3 production remained consistent across various heights, with HO2+NO as the major O3 production pathway, followed by RO2+NO. We saw P (O3)net decreased with the increase of the measurement height, primarily attributed to the decreased O3 precursors anthropogenic organic compounds (AVOC) and oxygenated volatile organic compounds (OVOC). O3 formation regimes were similar at different heights during both episodes and non-episodes, which was located either in volatile organic compounds (VOCs) sensitive regime or in transition regime and more sensitive to VOCs. Diurnally, photochemical O3 formation typically remained in the VOCs sensitive regime during the morning and noon time, but in the transitional regime and more sensitive to VOCs in the afternoon at around 16:00 LT. The vertical and temporal O3 formation are most sensitive to AVOC and OVOC, which suggests that targeting VOCs, especially AVOC and OVOC, for control measures is more practical and feasible at the observation site. The vertical temporal analysis of O3 formation mechanisms near the ground surface in this study provides critical foundational knowledge for formulating effective short-term emergency and long-term strategies to combat O3 pollution in the PRD region of China. [ABSTRACT FROM AUTHOR]