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In this study, the iron-based carbon composite (hereafter FCN-x, x = 0, 400, 500, and 600 calcination) was synthesized by a simple high-temperature pyrolysis method using iron-containing sludge coagulant generated from wastewater treatment settling ponds in chemical plants. The FCN-x was used for the adsorptive reduction of aqueous phase Cr(VI) effectively. The FCN-x was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier infrared spectrometer (FT-IR), X-ray photoelectron spectrometer (XPS), and Brunauer-Emmett-Teller theory (BET). FCN-x adsorption of Cr(VI) was examined in batch experiments using CrO42− as a function of physicochemical parameters. The chemical kinetics of Cr(VI) adsorption by FCN-500 were modeled by 1st and 2nd order empirical pseudo kinetics. Based on these experiments, FCN-500 has been selected for further studies on Cr(VI) adsorptive reduction. The maximum Cr(VI) adsorption by FCN-500 was 52.63 mg/g showing the highest removal efficiency. The Cr(VI) adsorption by the FCN-500 was quantified by the Langmuir isotherm. XPS result confirmed the reduction of Cr(VI) to Cr(III) by the FCN-500. The iron-based carbon composites have high reusability and application potential in water treatment. The electroplating wastewater with 117 mg/L Cr(VI) was treated with FCN-500, and 99.93% Cr(VI) was removed within 120 min, which is lower than the national chromium emission standard of the People’s Republic of China. This work illustrates the value-added role of sludge generated from dye chemical plants to ensure environmental sustainability.

The resource, environment, and ecological value of drinking reservoirs have received widespread concerns due to the pollution of persistent organic pollutants such as polycyclic aromatic hydrocarbons (PAHs). Therefore, we comprehensively studied the occurrence, source, distribution, and risk assessment of representative PAHs in Fengshuba Reservoir (FSBR) (large drinking reservoir, China). The total concentrations of 16 USEPA PAHs in the water phase, porewater phase, sediment phase, and soil phase were in ranges of 109.72–393.19 ng/L, 5.75–35.15 μg/L, 364.4–743.71 μg/kg, and 367.81–639.89 μg/kg, respectively. The naphthalene (Nap) was the dominant PAHs in the water phase, while it was Nap and phenanthrene (Phe) in porewater, sediment, and soil phase. The main sources of PAHs in FSBR were biomass combustion. Redundancy analysis indicated that the NTU, NO2-, NH4+, Chl-α, and IC were the dominant factors influencing the PAH distribution in water phase, and the PAHs in sediment phase was affected by T and NO3-. Pseudo-partitioning coefficients indicated that the PAHs in the porewater phase were more likely to migrate to the sediment phase. Risk assessment indicated that the PAHs both in the water and sediment phases were generally in a low-risk state, while the PAHs in the soil phase were in a moderate-risk state, and the Nap was in a high-risk state, and exposure to the PAHs in FSBR through drinking and skin exposure had little impact on consumers’ health. In summary, Nap could be used as a key indicator to evaluate the existence and potential risk of PAHs in FSBR.

Recently, pharmaceutical and personal care products (PPCPs) have been of wide concern due to their ecological toxicity, persistence, and ubiquity in aquatic environments. Peroxymonosulfate-based advanced oxidation processes (PMS-AOPs) have shown great potential for eliminating PPCPs due to their superior oxidation ability and adaptability. Biochar-based nanohybrids have been employed as emerging catalysts for peroxymonosulfate (PMS) activation. Until now, few researchers have summarized PMS activation by biochar-based catalysts for PPCPs removal. In this review, the types, sources, fates, and ecological toxicities of PPCPs were first summarized. Furthermore, various preparation and modification methods of biochar-based catalysts were systematically introduced. Importantly, the application of activating PMS with biochar-based multifunctional nanocomposites for eliminating PPCPs was reviewed. The influencing factors, such as catalysts dosage, PMS dosage, solution pH, temperature, anions, natural organic matters (NOMs), and pollutants concentration were broadly discussed. Biochar-based catalysts can act as electron donors, electron acceptors, and electron shuttles to activate PMS for the removal of PPCPs through radical pathways or/and non-radical pathways. The degradation mechanisms of PPCPs are correlated with persistent free radicals (PFRs), metal species, defective sites, graphitized degree, functional groups, electronic attributes, and the hybridization modes of biochar-based catalysts. Finally, the current problems and further research directions on the industrial application of biochar-based nanocomposites were proposed. This study provides some enlightenment for the efficient removal of PPCPs with biochar-based catalysts in PMS-AOPs.

The contamination of nutrients has caused considerable worry about the environment, resource value, and ecological worth of drinking water reservoirs. Therefore, we comprehensively studied the abundance, sources, distribution, and environmental behavior of carbon, nitrogen, and phosphorus in Fengshuba Reservoir (FSBR) (a large drinking reservoir, China). A graded leaching technique (introduced in 2003), the European Standard, Measurement and Testing (SMT) protocol, and spectrometry combined with parallel factor analysis (EEMs-PARAFAC) were used to assess nitrogen, phosphorus forms, and spectra data in the sediment and soil phases, respectively. The study demonstrates that seasonal hydrological variation had no significant effect on the nutrient abundance and nutrient structure composition of the FSBR, while different environmental media (e.g., sediment and soil phase) exhibited considerable differences in nutrient abundance, composition, and environmental behavior. The abundance of colored dissolved organic matter (CDOM), as well as molecular weight, aromatization degree, and humification degree of dissolved organic matter (DOM) were all lower in sediments than in soils, whereas the authigenic component was greater than in soils. Microbial-derived humus (C1), terrestrial-derived humus (C2), and protein-like tryptophan (C3) were identified as the three primary fluorescence components. Principal component analysis indicated that three components were closely associated with phosphorus in the sediment phase, whereas nitrogen and phosphorus in the soil phase were mainly related to C1 and C2. In summary, soil media (drawdown area) must be carefully considered in the management and control of water environment nutrients in reservoirs.

Antibiotic pollution of water resources is a global problem, and the development of new treatments for destroying antibiotics in water is a priority research. We successfully manufactured recyclable magnetic Fe3O4/g-C3N4 through the electrostatic self-assembly method. Selecting tetracycline (TC) as the target pollutant, using Fe3O4/g-C3N4 and H2O2 developed a heterogeneous optical Fenton system to remove TC under visible light. Fe3O4/g-C3N4 was systematically characterized by SEM, TEM, XRD, FTIR, XPS, DRS, and electrochemical methods. The removal efficiency of 7% Fe3O4/g-C3N4 at pH = 3, H2O2 = 5 mM, and catalyst dosage of 1.0 g/L can reach 99.8%. After magnetic separation, the Fe3O4/g-C3N4 photocatalyst can be recycled five times with minimal efficiency loss. The excellent degradation performance of the prepared catalyst may be attributed to the proper coupling interface between Fe3O4 and g-C3N4 which promotes the separation and transfer of photogenerated electrons. Photogenerated electrons can also accelerate the conversion of Fe3+ to Fe2+, thereby producing more ˙OH. The new Fe3O4/g-C3N4 can be used as a raw material for advanced oxidation of water contaminated by refractory antibiotics.

The contamination of nutrients has caused considerable worry about the environment, resource value, and ecological worth of drinking water reservoirs. Therefore, we comprehensively studied the abundance, sources, distribution, and environmental behavior of carbon, nitrogen, and phosphorus in Fengshuba Reservoir (FSBR) (a large drinking reservoir, China). Seasonal hydrological circumstances had little influence on the nutrient abundance and structural component of the FSBR, while carbon, nitrogen, and phosphorus abundance, composition, and environmental behavior varied significantly between various environmental media (sediment and soil phases). Microbial-derived humus (C1), terrestrial-derived humus (C2), and protein-like tryptophan (C3) were identified as the three primary fluorescence components using parallel factor analysis. The abundance of colored dissolved organic matter (CDOM), molecular weight, aromatization degree, and humification degree of dissolved organic matter (DOM) in the sediment were lower than in the soil, whereas the authigenic component was greater than in the soil, according to spectral index analysis. The main sources of humus in FSBR were biogenic contributions. Principal component analysis indicated that three components were closely associated to phosphorus in the sediment phase, whereas nitrogen and phosphorus in the soil phase were mainly related to C1 and C2. In summary, in the management and control of water environment nutrients in reservoirs, soil media in the riparian zone must be carefully considered.

This study investigated the AQI (air quality index) and atmospheric pollutants including PM2.5, PM10, CO, SO2, NO2 and O3 in Chongqing, Luzhou and Chengdu from 2017 to 2019. In addition, the impacts of the COVID-19 event on the air quality in the three cities in 2020 were compared and discussed. For the combined AQIs for the three cities, in spring, the daily AQIs ranged between 25 and 182 and averaged 72.1. In summer, the daily AQIs ranged between 24 and 206 and averaged 77.5. In autumn, the daily AQIs ranged between 22 and 170 and averaged 61.1, and in winter, the daily AQIs ranged between 28 and 375 and averaged 99.6. The distributions of the six AQI classes in spring were 3%, 94%, 3%, 0%, 0%, and 0%; in summer, they were 11%, 74%, 15%, 0%, 0% and 0%; in autumn, they were 29%, 70%, 1%, 0%, 0%, and 0%, and in winter, they were 1%, 52%, 44%, 3%, 0%, and 0%, respectively. The average AQIs, in order, were Chengdu (85.4) > Chongqing (73.8) > Luzhou (73.2). Both the highest AQIs and PM2.5 (as the major indicatory air pollutant) occurred mainly in the low temperature season (January, December, and February), while O3 was the main air pollutant in June and August when the weather was hot. In February 2020, during the epidemic prevention and control actions taken in response to COVID-19 for the three cities, the combined AQIs for the top five days with the highest AQIs in February 2020 was 79.4, which was 23.6% lower than that from 2017–2019 (AQI = 100.7), and the average concentrations of PM2.5, PM10, SO2, CO, and NO2 were 89.4 µg m–3, 106 µg m–3, 2.31 ppb, 0.72 ppm, and 12.3 ppb, respectively, and were 17.9%, 30.8%, 83.8%, 19.8%, and 62.1%, lower than those in February 2017–2019. However, the average O3 concentration (31.8 ppb) in February 2020 rather than decreasing, increased by 6.2%. This is because a lower NO2 concentration hindered the NO + O3 reaction and led to increase O3 concentration in the ambient air.

Both the air quality index (AQI) and indicatory air pollutants of Anqing, Hefei, and Suzhou near central China from 2017 to 2019, and the impact of COVID-19 epidemic prevention and control actions on air quality were investigated. The combined data for the three cities from 2017 to 2019 indicated that the lowest AQI (averaged 78.1) occurred in the summer season, for which the AQI proportions for classes I, II, III, IV, V, and VI were 25.6%, 49.9%, 21.9%, 2.7%, 0%, and 0%, respectively. The highest (AQI average of 112.6) was in winter, for which the proportions were 7.4%, 39.5%, 33.3%, 12.5%, 7.2%, and 0.1%, respectively. PM2.5, PM10, and NO2 in order were the most important indicatory air pollutants for AQI classes IV, V, and VI, which all prevailed in winter and spring, while O3 was the indicatory air pollutant that occurred most in summer. The COVID-19 event, which triggered global attention, broke out at the end of 2019. This study also investigated and compared the air quality levels in the three cities from January to March 2017–2019 with those in 2020. The results showed that during February 2020, in the three cities, the average ambient air concentrations of PM2.5, PM10, SO2, CO, and NO2 were 41.9 µg m–3, 50.1 µg m–3, 2.18 ppb, 0.48 ppm, and 8.97 ppb, and were 46.5%, 48.9%, 52.5%, 36.2%, and 52.8%, respectively, lower than those in the same month in 2017–2019, respectively. However, the O3 average concentration (80.6 ppb) did not show significant fluctuations and even slightly increased by 3.6%. This is because a lower concentration of NO2 resulted in constraints on the reaction of NO + O3, so the O3 level could not be effectively further reduced. In addition, this study also analyzed and compared the five highest daily AQIs from February 2017–2019 with those of 2020 for the three cities. The mean AQI for the 5 days with the highest daily AQI (averaged 122.6) in February 2020 was 45.1% lower than that for February 2017–2019 (averaging 223.2), and the indicatory air pollutant was always PM2.5, which decreased by 46.7% (from 173.6 to 92.6 µg m–3). It is clear that during the COVID-19 epidemic prevention and control action periods, the air quality near central China improved significantly.

In early 2020, the COVID-19 epidemic spread globally. This study investigated the air quality of three cities in Hubei Province, Wuhan, Jingmen, and Enshi, central China, from January to March 2017–2020 to analyze the impact of the epidemic prevention and control actions on air quality. The results indicated that in the three cities, during February 2020, when the epidemic prevention and control actions were taken, the average concentrations of atmospheric PM2.5, PM10, SO2, CO, and NO2 in the three cities were 46.1 µg m–3, 50.8 µg m–3, 2.56 ppb, 0.60 ppm, and 6.70 ppb, and were 30.1%, 40.5%, 33.4%, 27.9%, and 61.4% lower than the levels in February 2017–2019, respectively. However, the average O3 concentration (23.1, 32.4, and 40.2 ppb) in 2020 did not show a significant decrease, and even increased by 12.7%, 14.3%, and 11.6% in January, February, and March, respectively. This is because a lower concentration of NO2 resulted in constraints on the NO + O3 reaction, and the O3 could not be effectively further depleted. In addition, the average air quality index (AQI) for the three cities in January, February, and March 2020 were 32.2%, 27.7%, and 14.9% lower than the levels in 2017–2019, respectively. Based on the AQIs for the three cities, the combined proportions of Class I and Class Ⅱ in January, February, and March 2020 increased by 27.9%, 24.8%, and 4.3%, respectively, while the combined proportion of AQI Classes III, IV, V, and VI was reduced from 34.8% to 15.8%. In addition, in the first three months of 2020, the indicatory air pollutants in the three cities for the AQIs were predominant in the following order: PM2.5 (72.0%), O3 (16.4%), PM10 (8.3%), NO2 (2.9%), and CO (0.4%). This study provides useful information for establishing a scientific air pollution control strategy and is a valuable reference for future research on improving urban air quality.

The COVID-19 epidemic discovered and reported at the end of December 2019 and began spreading rapidly around the world. The impact of the COVID-19 event on the trip intensity, AQI (air quality index), and air pollutants, including PM2.5, PM10, SO2, CO, NO2, and O3 in Shenzhen, Guangzhou, and Foshan (the so-called ‘three cities’) from January 12 to March 27, in 2019 and 2020, are compared and discussed. In 2020, the combined trip intensity in the three cities ranged between 0.73 and 5.54 and averaged 2.57, which was 28.4% lower than that in 2019. In terms of the combined AQIs for the three cities, from January 12 to March 26, 2020, the daily AQIs ranged between 21.0 and 121.3 and averaged 56.4, which was 16.0% lower than that in 2019. The average AQIs in order were Guangzhou (57.5) > Foshan (54.1) > Shenzhen (44.1). In 2019, the distribution proportions of the six AQI classes were 45.2%, 50.4%, 4.40%, 0%, 0%, and 0%, respectively, while those in 2020 were 62.7%, 37.3%, 0%, 0%, 0% and 0%, respectively. For the combined data for the three cities, on the top five days with the highest AQIs during the epidemic period, the average concentrations of PM2.5, PM10, SO2, CO, NO2, and O3 were 76.4 μg m–3, 113.4 μg m–3, 5.14 ppb, 0.88 ppm, 36.5 ppb and 55.5 ppb, which were 55.2%, 49.4%, 55.1%, 30.0%, 45.1% and 15.5% lower than those during the non-epidemic period (from January 12 to March 27, 2017–2019). The above results revealed that the comprehensive strict epidemic prevention and control actions reduced trip intensity and improved the air quality significantly.

A methodology for the high-precision prediction and risk assessment of antibiotics at the watershed scale was established. Antibiotic emission inventory and attenuation processes were integrated into the MIKE 11 model to predict the spatiotemporal distribution of norfloxacin, ofloxacin, enrofloxacin, erythromycin, roxithromycin, and sulfamethoxazole in the Nanfei River watershed, China. Considering the variations in antibiotic removal in sewage treatment plants, manure composting, and lagoon systems, the high, medium, and low removal efficiencies of selected antibiotics across China were obtained and used as the best, expected, and worst scenarios, respectively, to evaluate the uncertainty of antibiotic emissions. The predicted concentrations were comparable to antibiotic measurements after flow calibration. The prediction results showed that the highest concentration exposures were mainly concentrated in urban areas with a dense population. Flow variations controlled the temporal distribution characteristics of antibiotics via the dilution effect, and the concentrations of antibiotics in the dry season were 3.1 times higher than those in the wet season. The median concentrations of norfloxacin and erythromycin ranged from 111.36 ng/L to 592.33 ng/L and 106.63 ng/L to 563.01 ng/L, respectively, which both posed a high risk to cyanobacteria and a medium risk to spreading antibiotic resistance. Scenario analysis further demonstrated that high removal efficiencies of these antibiotics can considerably reduce the potential ecotoxicity risks and bacterial resistance selection. The developed methodology for predicting the distribution and risk of antibiotics was suitable for the risk assessment and control strategy of human- and livestock-sourced pollutants.

Bimetallic catalysts are often used for peroxymonosulfate (PMS) activation in recent years due to the synergistic effects between two different metal species. However, the synergy between Zn and other transition metal in PMS activation are rarely studied because of the ease of evaporation of Zn species at high temperature. In this work, a Co/Zn co-doped carbonaceous catalyst derived from ZIF-67@ZIF-8 (Z67@8D) was prepared successfully by the core-shell replacement strategy, and used to activate PMS for sulfamethoxazole (SMX) degradation. Due to the co-existence of Co/Zn species (e.g., Co/Zn-N site), Z67@8D showed a much higher catalytic activity than that of Z8D, Z67D, and several commercial oxides. Importantly, the CoZn synergy was deeply revealed by combining experiments and density functional theory (DFT) calculations, in which Zn could adjust the electron distribution of Co, reducing the PMS adsorption energy and thus enhancing PMS decomposition and singlet oxygen (

As an emerging peroxymonosulfate (PMS) activation catalyst, graphitic carbon nitride (g-C

Polymeric carbon nitride (PCN) has been extensively employed in peroxymonosulfate (PMS) activation for water decontamination. However, limited photocatalytic efficiency can be achieved by pristine PCN due to its intrinsic deficiencies like high electron-hole recombination rate and resistance to charge transfer. Herein, in a two-stage thermal treatment process, the nontoxic and stable Na and K were successfully anchored among the PCN skeleton with surface defects created, leading to an elevated photocatalytic activity for PMS activation. The SO4·- and 1O2 were identified as the dominant reactive oxygen species, which were generated from electron transfer processes between PMS and catalyst. Experimental and theoretical analyses suggested that the defective structures and metal dopants improved the optical properties of catalyst, endowing it a wider light absorption range and a lower energy barrier for electron transitions. The modified structures were also beneficial to electron transfer processes due to the weaker electron confinement effect, accelerating the production of SO4·- on the defective sites and 1O2 on the metal sites. The synergy of radical and non-radical species weakened the influence of side reactions between radicals from PMS and coexisting inorganic anions in practical water, hence to promote the resistance of modified catalysts in complex water matrices.

Retarding the fuel injection timing is an effective strategy for controlling NOx emissions from diesel engines. However, the influence of retarding the fuel injection timing on polycyclic aromatic hydrocarbon (PAH) and persistent organic pollutant (POP) emissions has not yet been investigated. In this study, the diesel engine was tested using four of the existing thirteen European steady state cycle (ESC) modes. The fuel injection timing was retarded from –8° to –6° and the diesel exhaust gas samples were analyzed for PAH and POP emissions. The NOx emission factor reduced by ~25% when the fuel injection timing was retarded. However, the strategy had a negative effect on combustion efficiency. The carbon monoxide (CO) and particulate matter (PM) emissions were 1.4 and 1.2 times higher for the –6° scenario, respectively. The emission factors of all the toxic organic pollutants increased drastically when the fuel injection timing was retarded. For instance, the emission factors of PAH and polychlorinated dibenzo-p-dioxin/dibenzofuran (PCDD/F) for the –6° scenario, based on BaPeq and WHO-TEQ, were 22 and 10 times higher than for the –8° scenario. The retardation had more influence on these pollutants in the particle-phase than in gas-phase. The resultant negative impact on combustion increased the emissions of products of incomplete combustion, enhancing the potential of POP formation via de novo synthesis. The study concludes that although retarding the fuel injection timing leads to a decrease in NOx emissions from diesel engines, it also results in an increase in PAH and POP emissions.

This study investigates the emission characteristics of toxic organic pollutants (PAHs, PCDD/Fs, and PCBs) generated by a heavy-duty diesel engine operating at various exhaust gas recirculation (EGR) rates during steady-state cycles. Tests on the exhaust gas composition were conducted before and after changing the EGR ratio. The fuel used in the study (B2 diesel) was a mixture of 2% biodiesel and 98% diesel. The main focus was on the emission factors for the organic toxic pollutants in the exhaust gas after EGR ratios of 0% and 5% were applied. At an EGR ratio of 5%, the total mass emission factors for the PAHs and PCBs increased by 9.1 times and 14.4 times, respectively, while the toxicity equivalent factors increased by 4.0 times and 4.8 times, respectively. A significant increase in pollutants with a higher molecular weight, particularly for the PAHs, was observed after applying an EGR ratio of 5%, implying incomplete combustion. The emission factors of carbon dioxide (CO2) and nitric oxides (NOx) decreased by 2.5% and 54.4%, respectively, when the EGR ratio was increased from 0% to 5%, but those of PM and carbon monoxide (CO) increased by 60.5% and 66%, respectively. Therefore, a combination of control strategies is necessary in order to achieve a significant reduction in the emission of all pollutants.

Particulate matter (PM) pollution (including PM2.5 and PM10), which is reportedly caused primarily by industrial and vehicular emissions, has become a major global health concern. In this study, we aimed to reveal spatiotemporal characteristics and diurnal patterns of PM2.5 and PM10 data obtained from 50 air quality sensors situated in public bike sites in Kaohsiung City on June and November 2018 using principal component analysis (PCA). Results showed that PM concentrations in the study were above the standard World Health Organization criteria and were found to be associated, although complicated, with relative humidity. Specifically, the relationship between PM concentrations and relative humidity suggest a clear association at lower PM concentrations. Temporal analysis revealed that PM2.5 and PM10 occurred at higher concentrations in winter than in summer, which could be explained by the long-range transport of pollutants brought about by the northeast monsoon during the winter season. Both PM fractions displayed similar spatial distribution, wherein PM2.5 and PM10 were found to be concentrated in the heavily industrialized areas of the city, such as near petrochemical factories in Nanzih and Zuoying districts in north Kaohsiung and near the shipbuilding and steel manufacturing factories in Xiaogang district in south Kaohsiung. A pronounced diurnal variation was found for PM2.5, which generally displayed higher peaks during the daytime than in the nighttime. Peaks generally occurred at 7:00–9:00 a.m., noontime, and 5:00–7:00 p.m., while minima generally appeared at nighttime. The diurnal pattern of PM was greatly influenced by a greater number of industrial and human transportation activities during the day than at night. Overall, a number of factors such as relative humidity and type of season, transboundary pollution from neighboring countries, and human activities, such as industrial operations and vehicle use, affects the PM quality in Kaohsiung City, Taiwan.

Cooking oil fumes (CF) coming from night market stalls exhaust contain substantial amounts of air pollutants such as carbonyl compounds that may contribute to outdoor air pollution and may have adverse health effects on the Taiwanese population. Carbonyl emission characteristics depend on several factors, which include but are not limited to, the cooking style and food material being used. The current study evaluated carbonyl compound emissions from two scenarios: a standard kitchen cooking classroom with a stack gas tunnel and night market food stalls. The different cooking styles and food types cooked using a liquefied petroleum gas (LPG) stove, such as grilled chicken with (GCS) and without sauce (GC), mixed barbecue with sauce (MBS), grilled vegetables with sauce (GVS), stir-fried oyster omelet (OM), fried Taiwanese chicken nuggets (FN) in the kitchen cooking classroom, and grilled chicken with (GCS) and without sauce (GC), stir-fried oyster omelet (OM), grilled vegetables with sauce (GVS), and fried steak (FS) in the night market were evaluated for carbonyl carbon emissions. OM from the kitchen classroom and GCS from the night market showed the highest mean total carbonyl compound concentrations (1850 ± 682 ppb and 1840 ppb). Formaldehyde was found to be the most predominant carbonyl compound, with contribution percentages ranging from 70.9–99.58% of the total carbonyl emission factors in CFs. Grilled vegetables with sauce had the highest emission factor magnitude of 274 µg kg–1 wt. Factors such as the addition of sauce and grilling were also observed to increase carbonyl compound emissions. Corresponding health risks of carbonyl compounds in CFs for the night market vendors were also assessed. All values for cancer risk (R) were above the standard R value for workplace exposure, and HQ values were all greater than 1, suggesting a high risk for adverse health effects. Although our reported values were relatively high due to our sampling conditions, our study was first to be conducted in Taiwan and holds an important contribution to the global existing data of carbonyl compound emissions.

This study investigated the atmospheric PM2.5, PM10, SO2, NO2, CO, and O3 in Urumqi and Turfan cities from 2015 to 2017. In addition, six AQI categories and AQI values and seasonal changes in the major pollutants in Urumqi and Turpan were studied. In the three-year (2015–2017) study, in Urumqi, the average proportion of grades I, II, III, IV, V, and VI in spring were 16.3%, 59.7%, 16.0%, 5.33%, 2.67%, and 0%, respectively, were 12.0%, 82.7%, 5.33%, 0%, 0%, and 0% in summer; were 13.3%, 65.7%, 16.3%, 3.33%, 1.33%, and 0% in fall, and were 0.667%, 14.3%, 22.3%, 15.3%, 33.7%, and 13.7% in winter. In the Turpan region, the mean proportion of Grade I, II, III, IV, V, and VI pollutants were 0%, 61%, 21.3%, 8.00%, 2.33%, and 7.33% in spring, respectively; were 0.67%, 74.7%, 20.0%, 2.00%, 0.67%, and 2.00% in summer, were 1.33%, 59.7%, 42.3%, 7.67%, 0.33%, and 2.00% in fall, and were 0%, 11.0%, 35.3%, 29.3%, 20.3%, and 4.00% in winter. In the three-year (2015–2017) study, based on the results of the survey, it was determined that two cities have the best air quality in summer and the worst air quality in winter. In Urumqi, when the AQI was between 101–150, the main air pollutants in 2015 were PM2.5 and PM10. In 2016, the main air pollutant was PM2.5, and in 2017, the main air pollutants were PM2.5 and PM10. In Turpan, the main air pollutants in 2015 were PM2.5 and PM10, were PM2.5, PM10, and O3 in 2016, and was PM10 in 2017. When the AQI was between 151 and 200, in Urumqi, the main atmospheric pollutant in the three-year period was PM2.5. In Turpan, the main atmospheric pollutants in the three-year period were PM2.5 and PM10. When the AQI was between 201 and 300 in Urumqi, PM2.5 was the main atmospheric pollutant from 2015–2017. In Turpan, the main atmospheric pollutants in the three-year period were PM2.5 and PM10. To summarize, in both Urumqi and Turpan, PM2.5 and PM10 were the most predominant air pollutants causing high AQI values. More attention should thus be paid to the sources and reduction of these pollutants.

The resource, environment, and ecological value of drinking reservoirs have received widespread concerns due to the pollution of persistent organic pollutants such as polycyclic aromatic hydrocarbons (PAHs). Therefore, we comprehensively studied the occurrence, source, distribution and risk assessment of representative PAHs in Fengshuba Reservoir (FSBR) (large drinking reservoir, China). The total concentrations of 16 USEPA PAHs in the water phase, porewater phase, sediment phase and soil phase were in ranges of 109.72-393.19 ng/L, 5.75-35.15 μg/L, 364.4-743.71 μg/kg and 367.81-639.89 μg/kg, respectively. The naphthalene (Nap) was the dominant PAHs in the water phase, while it was Nap and phenanthrene (Phe) in porewater, sediment and soil phase. The main sources of PAHs in FSBR were biomass combustion. Redundancy analysis indicated that, the NTU, NO2-, NH4+, Chl-α and IC were the dominant factor influencing the PAHs distribution in water phase and the PAHs in sediment phase was affected by T and NO3-. Pseudo-partitioning coefficients indicated that the PAHs in the porewater phase was more likely to migrate to the sediment phase. Risk assessment indicated that the PAHs both in the water and sediment phases were generally in a Low-risk state, while the PAHs in the soil phase were in a Moderate-risk state and the Nap was in a High-risk state, and exposure to the PAHs in FSBR through drinking and skin exposure had little impact on consumers' health. In summary, Nap could be used as a key indicator to evaluate the existence and potential risk of PAHs in FSBR.

In this work, lignin peroxidase (LiP) was extracted for the in vitro degradation of a persistent compound (propranolol, PPN). The results showed that 94.2% of PPN was degraded at 30 U L

Silver nanomaterials (Ag NMs) are fabricated by many biological components in our environment. Recently, research on their biosynthesis and reactions has become a focus of attention. Due to the complexity of biological systems and samples, specific processes and mechanisms involving Ag NMs are difficult to identify and elucidate on the molecular and chemical-bond level. The microorganisms and composite components of plant extracts are of great interest in many biological syntheses. Although potential biomolecules have been shown to play essential roles in biological systems in Ag NM biosynthesis, the detailed mechanism of the electron transfer process and crucial molecules that control this reaction have only recently come into focus. The reactive behavior of the Ag NMs is of great significance for understanding their overall behavior and toxicity. Additionally, only limited knowledge is available about their kinetics. All reactions involve chemical bond formation, electron transfer, or electrostatic interactions. An overview is presented of the biosynthesis of Ag NMs based on molecular supports including a nitrate reductase/NADH oxidase-involved electron transfer reaction and their mechanisms in Ag+ reduction: quinol-mediated mechanism and superoxide-dependent mechanism, and molecular supports in plant extracts, is presented. The environmental reaction kinetics and mechanisms of the interactions of Ag NMs with substances are introduced based on the formation and classification of chemical bonds. The particle-particle reaction kinetics of Ag NMs in the environment are discussed to directly explain their stability and aggregation behavior. The toxicity of Ag NMs is also presented. In addition, future prospects are summarized. This review is the first to provide an insight into the mediating molecules and chemical bonds involved in the biosynthesis, kinetics, and mechanisms of action of Ag NMs.

During 2015–2017, the atmospheric PM2.5, PM2.5/PM10, PCDD/Fs, PCDD/F phase distribution and PM2.5-bound total PCDD/Fs-WHO2005-TEQ content in Wuhu and Bengbu were investigated in this study. In addition, the sensitivity analysis for PM2.5-bound total PCDD/Fs-WHO2005-TEQ of Wuhu was also studied. During 2015–2017, the three-year average PM2.5 concentration in Wuhu was 53.0 µg m–3, and in Bengbu was 61.4 µg m–3; the results also showed the annual average PM2.5 concentrations of these two cities had declined, but the levels were still far above the WHO annual PM2.5 standard (10 µg m–3). In addition, in Wuhu, the PM2.5-bound total PCDD/Fs-WHO2005-TEQ contents in summer (0.166 ng-WHO2005-TEQ g–1) were approximately only 68.8% in magnitude lower than the average value of other three seasons (0.532 ng-WHO2005-TEQ g–1), and that of Bengbu in summer (0.187 ng-WHO2005-TEQ g–1) was approximately 66.7% in magnitude lower than the average value of other three seasons (0.561 ng-WHO2005-TEQ g–1). Sensitivity analysis showed that the PCDD/F concentration was the most positively correlated sensitive factor for PM2.5-bound total PCDD/Fs-WHO2005-TEQ, and when ΔP/P was changed from 0% to +50%, ΔS/S responded from 0% to +106%. The second positively correlated sensitive factor was PM10 concentration, and when ΔP/P was changed from 0% to +50%, ΔS/S responded from 0% to +72%. This was followed by atmospheric temperature, and its effect was negatively correlated, when ΔP/P was changed from –50% to +50%, ΔS/S responded from +73% to –112%. The last sensitive parameter was PM2.5 concentration, with the impact divided into two stages: when ΔP/P was changed from 0% to+70%, ΔS/S responded from 0% to +33%, but when ΔP/P was changed from +70% to +100%, ΔS/S responded from +33% to +25%.The results of this study provide useful information that can be used to achieve more insights into both atmospheric PM2.5 and PCDD/Fs.

During the period 2016–2017, the atmospheric wet, dry, and total deposition fluxes and scavenging ratios of the total PCDD/Fs-WHO2005-TEQ in Handan and Kaifeng were investigated. In addition, a sensitivity analysis for the dry deposition fluxes of the total PCDD/Fs-WHO2005-TEQ was conducted. The annual wet deposition fluxes of total PCDD/Fs-WHO2005-TEQ in Handan ranged between 51.1 and 83.5 and averaged 72.3 pg WHO2005-TEQ m–2 year–1, which was approximately 1.04 times of magnitude higher than that in Kaifeng (69.3 pg WHO2005-TEQ m–2 year–1). From 2016–2017, the contribution fraction of dry deposition to the total PCDD/Fs-WHO2005-TEQ deposition flux ranged between 60.8% and 100% and averaged 80.4%. Dry deposition fluxes were more dominant than wet deposition fluxes. In terms of the seasonal variations in total PCDD/Fs-WHO2005-TEQ dry deposition fluxes (the mean values for 2016 and 2017) in Handan, those in spring, summer, fall, and winter were 1084, 563, 964, and 1325 pg WHO2005-TEQ m–2 month–1, respectively, while in Kaifeng, they were 963, 428, 715, and 1016 pg WHO2005-TEQ m–2 month–1, respectively. The total PCDD/Fs-WHO2005-TEQ deposition fluxes in winter was approximately 2.0 times of magnitude higher than that in summer. The sensitivity analysis of total PCDD/FsWHO2005-TEQ dry deposition fluxes in Handan and Kaifeng showed that the PM10 concentration was the most positively correlated sensitive factor. When ΔP/P was changed from 0% to +50%, ΔS/S responded from 0% to +46.1% and +46.3%, respectively. The second positively correlated sensitive factor was the PM2.5 concentration, where when ΔP/P was changed from 0% to +50%, ΔS/S responded from 0% to +47.8% and +40.8%, respectively. For PCDD/Fs mass concentration, when ΔP/P was changed from 0% to +50%, ΔS/S responded from 0% to +32.2% and +28.1%, respectively. This was followed by the atmospheric temperature, and its effect was negatively correlated. When ΔP/P was changed from –50% to +50%, ΔS/S responded from +46.4% to –26.9% and +57.0% to –30.5%, respectively. The results of this study provide useful information that can be used to achieve more insights into both atmospheric deposition of total PCDD/Fs-WHO2005-TEQ and the sensitive factors for dry deposition fluxes.

From 2015 to 2017, the atmospheric PM2.5, the total PCDD/Fs-WHO2005-TEQ concentrations, PM2.5-bound total PCDD/Fs-WHO2005-TEQ contents, and the gas-particle partitioning of PCDD/Fs in Handan and Kaifeng were investigated. In addition, a regression analysis of the air quality index (AQI) and total PCDD/Fs-WHO2005-TEQ concentration was also studied. From 2015-2017, in Handan, the three-year average PM2.5 concentrations in spring, summer, autumn and winter were 66.9, 61.3, 74.8, and 138 µg m–3, respectively and averaged 85.3 µg m–3, which was 1.2 orders of magnitude higher than that in Kaifeng (71.1 µg m–3). The three-year average PM2.5-bound total PCDD/Fs-WHO2005-TEQ content in spring, summer, autumn, and winter in Handan were 0.88, 0.28, 0.67, and 0.72 ng WHO2005-TEQ g–1, respectively, and averaged 0.64 ng WHO2005-TEQ g–1, which was 1.1 order of magnitude higher than that in Kaifeng (0.57 ng WHO2005-TEQ g–1). The three-year average fraction of gas phase total PCDD/Fs-WHO2005-TEQ concentrations in spring, summer, autumn, and winter in Handan were 26.4%, 62.8%, 28.9%, and 3.34%, respectively, and averaged 30.4%. The three-year average fraction of gas phase total PCDD/Fs-WHO2005-TEQ concentrations in Kaifeng (34.3%) was 1.1 order of magnitude higher than that in Handan (30.4%). Positive correlations between the AQI and the total PCDD/Fs-WHO2005-TEQ concentration were found and their R2 values in 2015, 2016, and 2017 were 0.929, 0.921, and 0.876, respectively. Therefore, the AQI can be used to roughly predict the level of total PCDD/Fs-WHO2005-TEQ in ambient air through the use of a regression equation in these two cities.

The atmospheric PM2.5, total PCDD/Fs-WHO2005-TEQ concentrations, PM2.5-bound total PCDD/Fs-WHO2005-TEQ content, gas-particle partitioning and wet deposition of PCDD/Fs in Jinan and Weihai, from 2015 to 2017, were investigated, respectively. Furthermore, a regression analysis of the air quality index (AQI) and total PCDD/Fs-WHO2005-TEQ concentrations was studied as well. From 2015–2017, the three-year average PM2.5 concentrations in Jinan and Weihai were 76.1 and 32.9 µg m–3, respectively. The three-year average total PCDD/Fs-WHO2005-TEQ concentrations in Jinan and Weihai were 0.0866 and 0.0396 pg-WHO2005-TEQ m–3, respectively, indicating that maritime climate regulation contributes to the spread of pollutants. The three-year average fraction of gas phase total PCDD/Fs-WHO2005-TEQ concentrations in spring, summer, autumn, and winter in Jinan were 26.1%, 63.8%, 30.5% and 4.62%, respectively; while, those in Weihai were 30.7%, 74.5%, 44.4%, and 8.41%, respectively. In 2016, the annual wet deposition fluxes in Jinan and Weihai were 1288 and 483 pg WHO2005-TEQ m–2 year–1, respectively. The annual scavenging ratios of total PCDD/Fs-WHO2005-TEQ were 33080 and 30870 in Jinan and Weihai, respectively. The total concentration of PCDD/Fs-WHO2005-TEQ increased with an increase of AQI and showed a positive correlation; the R2 values of three years (2015, 2016, and 2017) were 0.873, 0.847, and 0.744, respectively. Therefore, knowing the AQI value, the total concentration of PCDD/Fs-WHO2005-TEQ in the ambient air can be roughly estimated using a regression equation.

In this study, the atmospheric PM10, SO2, NO2, CO, and O3 concentration from 2015-2017, in Handan and Kaifeng were investigated. Besides, the seasonal variations of AQI values and their corresponding primary pollutants of six AQI grades were also discussed. In Handan, the daily AQI values ranged from 22 to 500 in 2015, from 19 to 500 in 2016, and from 27 to 500 in 2017, for which the corresponding average values were 143, 132 and 151, respectively. In Kaifeng, the daily AQI ranged from 25 to 496 in 2015, from 20 to 420 in 2016, and from 21 to 434 in 2017, for which the corresponding average values were 129, 124 and 131, respectively. During the three-year study, in Handan, the average proportion of grades I, II, III, IV, V and VI were 4.0%, 35.0%, 25.6%, 31.7%, 2.5% and 1.2% in spring; were 4.0%, 35.1%, 22.6%, 35.8%, 2.5% and 0% in summer; were 14.2%, 31.0%, 15.3%, 35.8%, 3.7% and 0% in fall, and were 3.3%, 26.1%, 20.0%, 37.8%, 8.1% and 4.7% in winter. In Kaifeng, the average proportion of grades I, II, III, IV, V and VI were 2.6%, 34.0%, 24.4%, 36.1%, 2.6% and 0.3% in spring; were 18.2%, 41.9%, 21.8%, 17.0%, 1.1% and and 0% in summer; were 8.6%, 34.3%, 17.4%, 34.8%, 4.9% and 0% in fall, and were 2.1%, 15.1%, 7.8%, 44.5%, 26.2% and 4.3% in winter. Overall, the air quality in the two cities were the worst in winter. The AQI values were between 101 and 150, where in Handan, PM2.5, PM10, and O3 were the primary air pollutants over the three years. In Kaifeng, the primary air pollutants were PM2.5, PM10, NO2, and O3 in 2015; were PM2.5, PM10, and O3 in 2016, and were PM2.5, PM10, and O3 in 2017. When AQIs ranged between 151 and 200, in Handan, the primary air pollutants were PM2.5, PM10, and O3 in both 2015 and 2016, and were PM2.5, PM10, NO2, and O3 in 2017. In Kaifeng, PM2.5, PM10, and O3 were the primary air pollutants from 2015-2017. When AQIs were between 201 and 300, in Handan, the primary air pollutants were PM2.5 and PM10 in 2015 and were PM2.5 and O3 in 2017. In Kaifeng, the primary air pollutants comprised PM10 in 2015, PM2.5 and PM10 in 2016, and PM2.5 and O3 at the same time. When the AQI values were between 301 and 500, which did not occur in Handan in 2015, the primary air pollutants comprised PM10 in 2016, PM2.5 and PM10 in 2017, and in Kaifeng from 2015-2017, PM2.5, and PM10 were the primary air pollutants. This study investigated the AQI values and corresponding primary pollutants in each season in more detail, the control strategies for these air pollutants will be more precisely.

From 2015–2017, the atmospheric PM10, SO2, NO2, CO, and O3 in Wuhu and Bengbu were investigated in this study. In addition, the AQI values and seasonal variations in six AQI classes and corresponding primary pollutants were also studied. In Wuhu, the daily AQI ranged from 23 to 298 in 2015, from 33 to 290 in 2016, and from 34 to 278 in 2017, and the corresponding mean values were 81, 80 and 90, respectively. In Bengbu, the daily AQI ranged from 23 to 288 in 2015, from 32 to 286 in 2016, and from 27 to 500 in 2017, and the corresponding mean values were 88, 89 and 97, respectively. During the three-year study, in Wuhu, the mean proportion of levels with Grade I, II, III, IV, V and VI were 9.33%, 69.3%, 18.3%, 3.00%, 0% and 0% in spring; were 35.0%, 55.0%, 7.00%, 3.00%, 0% and 0% in summer; were 13.6%, 65.0%, 18.0%, 3.33%, 0% and 0% in fall, and were 5.33%, 48.7%, 30.7%, 9.67%, 5.67% and 0% in winter. In Bengbu, the mean proportion of levels with Grade I, II, III, IV, V and VI were 3.00%, 64.0%, 30.3%, 2.67%, 0.333% and 0.333% in spring; were 19.3%, 68.7%, 11.3%, 0.667%, 0% and 0% in summer; were 20.7%, 56.3%, 17.3%, 4.67%, 1.00% and 0% in fall, and were 9.67%, 36.7%, 31.0%, 32.0%, 5.67% and 0% in winter. Generally, the air quality in the two cities were in the following order: summer > fall > spring > winter. AQI ranged between 101–150, where in Wuhu, the primary air pollutants were PM2.5 and NO2 in 2015; were PM2.5, NO2 and O3 in 2016, and were PM2.5, PM10, NO2 and O3 in 2017. In Bengbu, PM2.5, PM10 and O3 were the primary air pollutants during the three years. When AQIs ranged between 151 and 200, in Wuhu, the primary air pollutant was PM2.5 in 2015; were PM2.5 and PM10 in 2016, and were PM2.5, PM10, and O3 in 2017. In Bengbu, the primary air pollutant was PM2.5 in 2015 and 2016 and comprised PM2.5 and O3 in 2017. When AQIs were between 201 and 300, in Wuhu, PM2.5 was the primary air pollutant in 2015–2017. In Bengbu, the primary air pollutant was PM2.5 in 2015 and 2016 and comprised PM2.5 and PM10 in 2017. When the AQI ranged between 301–500, which did not occur in Wuhu from 2015–2017 or in Bengbu during 2015–2016, PM2.5 was as the primary air pollutant in Bengbu in 2017. When the AQI can be analyzed in more detail, the control strategies for air pollution will be more precise.

This study investigated atmospheric PM2.5 concentration, PM2.5/PM10 ratio, total PCDD/Fs concentration, PCDD/F phase distribution, PM2.5-bound total PCDD/Fs-WHO2005-TEQ content, and dry deposition of PCDD/Fs for Xiamen and Zhangzhou Cities during 2015–2017, and sensitivity analysis of both atmospheric PM2.5-bound total PCDD/Fs-WHO2005-TEQ content and dry deposition of PCDD/Fs in these two cities. During 2015–2017, the three-year average concentration of PM2.5 in Xiamen was 27.6 µg m–3, while that of Zhangzhou was 33.9 µg m–3; this level is still higher than the WHO annual PM2.5 standard (10.0 µg m–3). In addition, the summer PM2.5-bound total PCDD/Fs-WHO2005-TEQ content in Xiamen and Zhangzhou Cities was 0.131 ng-WHO2005-TEQ g–1 and 0.161 ng-WHO2005-TEQ g–1. And it is lower than the average of the other three seasons. In Xiamen, the average monthly dry deposition flux in these three years was 322 pg WHO2005-TEQ m–2 month–1, while that of Zhangzhou was 378 pg WHO2005-TEQ m–2 month–1, respectively. Sensitivity analysis of atmospheric PM2.5-bound total PCDD/Fs-WHO2005-TEQ content showed that the most sensitive parameters are total PCDD/F mass concentration and PM10 concentration, followed by atmospheric temperature and PM2.5 concentration; in addition, the sensitivity analysis of atmospheric dry deposition is similar to those of atmospheric PM2.5-bound total PCDD/Fs-WHO2005-TEQ content. The results of this study provide useful information for better understanding PM2.5, particle-bound PCDD/Fs content and PCDD/Fs dry deposition in the ambient air of urban cities.

Benzene dye intermediate (BDI) 4-methoxy-2-nitroaniline (4M2NA) wastewater has caused significant environmental concern due to its strong toxicity and potential carcinogenic effects. Reports concerning the degradation of 4M2NA by advanced oxidation process are limited. In this study, 4M2NA degradation by Fenton oxidation has been studied to obtain more insights into the reaction mechanism involved in the oxidation of 4M2NA. Results showed that when the 4M2NA (100 mg L−1) was completely decomposed, the TOC removal efficiency was only 30.70–31.54%, suggesting that some by-products highly recalcitrant to the Fenton oxidation were produced. UV-Vis spectra analysis based on Gauss peak fitting, HPLC analysis combined with two-dimensional correlation spectroscopy and GC-MS detection were carried out to clarify the degradation mechanism and pathway of 4M2NA. A total of nineteen reaction intermediates were identified and two possible degradation pathways were illustrated. Theoretical TOC calculated based on the concentration of oxalic acid, acetic acid, formic acid, and 4M2NA in the degradation process was nearly 94.41–97.11% of the measured TOC, indicating that the oxalic acid, acetic acid and formic acid were the main products. Finally, the predominant degradation pathway was proposed. These results could provide significant information to better understand the degradation mechanism of 4M2NA.

This study investigated the monthly average dry, wet and total deposition fluxes in total-PCDD/Fs-WHO2005-TEQ in Wuhu and Bengbu, respectively. In addition, sensitivity analyses for both scavenging ratio and wet deposition of total-PCDD/Fs-WHO2005-TEQ in Wuhu were also conducted. In 2015, the annual dry deposition fluxes, wet deposition fluxes, and total deposition fluxes were 6407, 1538, and 7945 pg WHO2005-TEQ m–2 year–1 in Wuhu, and were 7101, 1525, and 8626 pg WHO2005-TEQ m–2 year–1 in Bengbu. The annual scavenging ratios of total-PCDD/Fs-WHO2005-TEQ were 30144 and 31267 in Wuhu and Bengbu, respectively. As to the sensitivity analysis for the scavenging ratio of total-PCDD/Fs-WHO2005-TEQ, the most positive sensitivity parameters were PCDD/Fs concentration and PM10 concentration; the second positively correlated sensitivity parameter was PM2.5 concentration, then, followed by atmospheric temperature, which was negatively correlated; the last negative correlated sensitivity factor was the rainfall. In terms of the sensitivity analysis for wet deposition of total-PCDD/Fs-WHO2005-TEQ, the most positive sensitivity parameter was air temperature; the second positive or negative correlated sensitivity factor was atmospheric PCDD/Fs mass concentration, followed by PM2.5 and PM10 concentration, which were positively correlated; the last positive correlated sensitivity factor was the rainfall. This study led to greater insight into the parameters affecting the atmospheric wet deposition of PCDD/Fs, which will benefit development of appropriate control strategies for PCDD/Fs and provided useful information for the scientific community.

Volatile organic compounds (VOCs) emitted from electronic industry may pose severe problems to human health and the environment. In the present study, the VOCs adsorption on commercial activated carbon fibers (ACFs) in a fixed-bed column was investigated by continuous mode as a function of inlet flow rate (100–500 L/h), inlet VOCs concentration (200–400 mg/m3), adsorption temperature (15–35 °C) and bed height (120–240 mm). Afterwards, the adsorption behavior and mechanism of VOCs on ACFs were quantified by the adsorption kinetic, equilibrium, thermodynamic models. To further quantify the adsorption performance in the fixed bed column, an axial dispersion model was proposed to model the breakthrough curves. The results indicated that the adsorption process conformed to the Langmuir isotherm and pseudo-first-order kinetic equation, indicative of physical adsorption. Moreover, the adsorption capacity increased with the increase of VOCs concentration and bed height, but decreased with the increase of inlet flow rate and adsorption temperature. Interestingly, the axial dispersion model can well predict the breakthrough curve and visualize the temporal and axial distribution of VOCs adsorption in the fixed-bed column by integrating Matlab ode15s solver with lsqcurvefit function, from which both the overall mass transfer and axial dispersion coefficient were also derived. The model herein may facilitate the process design of VOCs adsorption and precisely predict the adsorption performance of a scaled-up adsorption fixed bed.

The metal-free graphitic carbon nitride is a promising photocatalyst for peroxymonosulfate (PMS) activation towards water decontamination, but bearing low efficiency due to its electronic structure and surface chemistry. Herein, the non-metallic element boron was adopted for catalyst development. The boron dopants and defects were simultaneously introduced by potassium borohydride, resulting in an excellent activity towards PMS activation. The dominant reactive oxygen species was singlet oxygen, which was determined to originate from PMS activation over photo-induced holes initiated by an electron transfer process. Calculations based on density functional theory revealed that at excited states, due to the dopants and defects, the electron-hole distribution was altered from an even population to a significant separation, which was beneficial for photocatalytic performance. Besides, the engineered electronic structure weakened the catalyst resistance to charge transfer, enabling easier electron transfer between the catalyst and the PMS. Moreover, the strengthened and enlarged positive electrostatic potential areas on heptazine rings oriented the electron transfer process from the negatively charged PMS to the catalyst, facilitating the generation of singlet oxygen. These findings provide underlying mechanism insights into the contribution of dopants and defects to catalytic performance on persulfate-based photocatalytic water treatment.