Catalytic ozonation of multi-VOCs mixtures over Cr-based bimetallic oxides catalysts from simulated flue gas: Effects of NO/SO2/H2O.

Different Cr-based bimetallic oxides were prepared, and their catalytic performance was evaluated on the simultaneous removal of multi-VOCs mixtures (acetone, benzene, toluene, and o-xylene) by ozonation. Among them, Co-Cr catalyst stood out in catalytic ozonation of aromatic VOCs, and its activity on acetone conversion was promoted by raising the temperature and ozone concentrations, owing to lower crystallization, larger surface area, excellent redox and VOCs/CO2 desorption ability. Above 95% conversion of all multi-VOCs was achieved over the Co-Cr catalyst when the temperature was 100 °C and an excess ozone ratio λ (the ratio of actual moles of ozone to theoretical moles of ozone needed) was equal to 3. A competitive relationship was noticed during the removal process of four multiple VOCs, with significant inhibition of acetone conversion in the presence of aromatic VOCs, conceivably due to adsorption competition and byproducts accumulation. Effects of NO/SO2/H2O and respective reversibility were also investigated. The inhibition effects of NO/SO2/H2O on aromatic VOCs were far less than those on acetone. Further, the retarding effect of NO was reversible, attributing to physical adsorption competition, but the inhibition effect of SO2/H2O was irreversible, due to the blockage of active sites for VOCs removal. With the combination of scrubbing, multi-VOCs and NO/SO2 could be removed by catalytic ozonation simultaneously and efficiently. In-situ DRIFTS measurement was also conducted to investigate the adsorption and catalytic ozonation process of multi-VOCs mixtures, as well as under the presence of SO2/H2O, discovering the major intermediates, surface carboxylates and carboxylic acids.

Urban park system on public health: underlying driving mechanism and planning thinking.

The driving mechanism and planning thinking of the impact of urban park system on public health the mission of urban geography, urban and rural planning or landscape architecture are to coordinate the relationship between people and places, people and nature. The municipal park system is an important part of the urban green space system. In order to effectively play the role of the urban park system in promoting the health of urban residents. This manuscript studies the coupling relationship between the "urban park system" and the "public health system" by building a coordination model, reveals the driving mechanism of the urban park system affecting the benign development of public health, and clarifies the positive driving effect of urban parks on public health. Finally, based on the analysis results, the manuscript considers the optimal development strategy of urban parks from the macro and micro levels to promote the sustainable development of urban public health.

Catalytic ozonation of dichloromethane at low temperature and even room temperature on Mn-loaded catalysts.

Five Mn-loaded catalysts were synthesized on γ-Al2O3, TiO2, ZrO2, nano γ-Al2O3 and nanoZrO2 supports. The catalytic ozonation of DCM (dichloromethane) was evaluated under industrial conditions (i.e., temperature, O3 input, H2O and SO2 content). According to results, >90% DCM conversion without O3 residue was achieved for all samples at 120 °C and an O3/DCM ratio of 6. At 20-120 °C, the highest Mn3+ content, abundant surface oxygen species and more weak acid sites led to the best performance of Mn/nanoAl2O3 (M/A-II). At 20 °C and 120 °C, 80% and 95% DCM can be degraded respectively on M/A-II at 20 °C with matched surface oxygen species and acidity. An O3/DCM ratio of 6 was optimal for performance and economy. For the effects of complex exhaust, both H2O and SO2 deactivated M/A-II. The H2O-induced deactivation was recoverable and also removed surface-deposited chlorine-containing species, enhancing the HCl selectivity. Finally, the Cl equilibrium of the reaction was comprehensively analyzed.

Effects of Coal-Fired Flue Gas Components on Mercury Removal by the Mechanochemical S-Modified Petroleum Coke.

In this work, the effects of coal-fired flue gas components (O2, CO2, SO2, and NO) on the Hg0 removal by the promising mercury removal adsorbent mechanochemical S-modified petroleum coke were characterized and analyzed in terms of the Hg0 removal efficiency, mercury adsorption capacity, and mercury mass balance. The results show that the mechanochemical S-modified petroleum coke with a theoretical sulfur content of 21% (named TSC-21) is the best candidate for mercury removal based on the Hg0 removal efficiency, Hg0 removal capacity, and difference ratio of Hg0 removal capacity (anti-interference ability) in the basic and full-component simulated flue gas atmosphere (N2 + O2 + CO2, N2 + O2 + CO2 + SO2 + NO). The maximum value (MV) and stable value (SV) of the Hg0 removal efficiency of TSC-21 in the basic simulated flue gas atmosphere are 99.25% (MV) and 91.17% (SV), respectively. O2, CO2, and NO all promote the Hg0 removal by the adsorbent, but they benefit the Hg0 oxidation while inhibiting the Hg0 adsorption. The promoting effect of O2 on the Hg0 removal by TSC-21 is affected by the reaction time, which is especially obvious after 1 min. The presence of SO2 inhibits the oxidation and adsorption of Hg0, which in turn reduces the Hg0 removal performance of the adsorbent. The improving effects on the oxidative escape of Hg0 by CO2 is higher than that by NO and O2. TSC-21 acts more as an oxidant than an adsorbent for Hg0 removal.

Hematological Effects and Benchmark Doses of Long-Term Co-Exposure to Benzene, Toluene, and Xylenes in a Follow-Up Study on Petrochemical Workers.

Benzene, toluene, and xylenes (BTX) commonly co-exist. Exposure to individual components and BTX-rich mixtures can induce hematological effects. However, the hematological effects of long-term exposure to BTX are still unclear, and respective reference levels based on empirical evidence should be developed. We conducted a follow-up study in BTX-exposed petrochemical workers. Long-term exposure levels were quantified by measuring cumulative exposure (CE). Generalized weighted quantile sum (WQS) regression models and Benchmark Dose (BMD) Software were used to evaluate their combined effects and calculate their BMDs, respectively. Many hematologic parameters were significantly decreased at the four-year follow-up (p < 0.05). We found positive associations of CE levels of benzene, toluene, and xylene with the decline in monocyte counts, lymphocyte counts, and hematocrit, respectively (ß > 0.010, Ptrend < 0.05). These associations were stronger in subjects with higher baseline parameters, males, drinkers, or overweight subjects (Pinteraction < 0.05). BTX had positive combined effects on the decline in monocyte counts, red-blood-cell counts, and hemoglobin concentrations (Ptrend for WQS indices < 0.05). The estimated BMDs for CE levels of benzene, toluene, and xylene were 2.138, 1.449, and 2.937 mg/m3 × year, respectively. Our study demonstrated the hematological effects of long-term BTX co-exposure and developed 8h-RELs of about 0.01 ppm based on their hematological effects.

Catalytic Decomposition of Residual Ozone over Cactus-like MnO2 Nanosphere: Synergistic Mechanism and SO2/H2O Interference.

Ground-level ozone is an irritant and is harmful to human respiratory and nervous systems. Thus, four manganese oxides with different crystals were hydrothermally synthesized to decompose residual ozone (deO3) in an ozone synergistic-oxidation system. Among them, a cactus-like MnO2-IV nanosphere exhibited the highest deO3 activity, with excellent tolerance to water vapor and SO2/H2O, which could maintain >88% deO3 efficiency in the high-humidity and sulfur-containing conditions. It benefits from the unique morphology, high specific surface area, superior redox properties, oxygen chemisorption capabilities, abundant surface-active hydroxyl species, and low valence Mn species. More importantly, the detailed interference mechanism of O2/O3/H2O/SO2 molecules on MnO2-IV was revealed utilizing in situ diffused reflectance infrared Fourier transform spectroscopy and X-ray photoelectron spectroscopy. H2O generally caused recoverable deactivation, but that caused by SO2 was irreversible. The synergistic effect of SO2/H2O promoted the formation of an unstable sulfate species, thereby deepening the deactivation but inhibiting the irreversible poisoning. Finally, nine specific steps to decompose ozone via surface-active hydroxyl/intermediates were established.

Comparative Study of Four Chemometric Methods for the Quantitative Analysis of the Carbon Content in Coal by Laser-Induced Breakdown Spectroscopy Technology.

Coal is a heterogeneous mineral substance mainly composed of carbon, along with various amounts of other elements. The carbon content is an important and pertinent parameter for coal quality. To achieve the rapid and accurate online measurement of the carbon content in coal, four different calibration strategies are applied to coal analysis by laser-induced breakdown spectroscopy (LIBS). Four calibration models based on support vector regression (SVR), back-propagation training (BP), random forest (RF), and partial least-squares regression (PLSR) were proposed, and the prediction accuracy, prediction precision, model stability, and training velocity of the four calibration models were compared for the quantitative analysis of the carbon content. A total of 65 coal samples were ablated, and the plasma spectra were used as the input data. Among the four calibration models, the results indicate that SVR and BP are the most promising calibration models for finding a better optimized model with a better prediction accuracy and prediction precision, and PLSR has a better prediction stability and a faster training velocity; however, RF has a prediction performance worse than those of the other three models.

Influence of benzene exposure, fat content, and their interactions on erythroid-related hematologic parameters in petrochemical workers: a cross-sectional study.

BACKGROUND: Ubiquitously distributed benzene is a known hematotoxin. Increasing evidence has suggested that erythroid-related hematologic parameters may be sensitive to benzene exposure. Fat content, which is also closely associated with erythroid-related hematologic parameters, may affect the distribution and/or metabolism of benzene, and eventually benzene-induced toxicity. METHODS: To explore the influence of benzene exposure, fat content, and their interactions on erythroid-related hematologic parameters, we recruited 1669 petrochemical workers and measured their urinary S-phenylmercapturic acid (SPMA) concentration and erythroid-related hematological parameters. Indices for fat content included body fat percentage (BF%), plasma total cholesterol (TC) and triglycerides (TG), and occurrence of fatty liver. RESULTS: The dose-response curve revealed U-shaped nonlinear relationships of SPMA with hematocrit (HCT) and mean corpuscular hemoglobin concentration (MCHC) (P-overall < 0.001, and P-nonlinear < 0.015), as well as positive linear associations and r-shaped nonlinear relationships of continuous fat content indices with erythroid-related hematological parameters (P-overall ≤0.005). We also observed modification effects of fat content on the associations between benzene exposure and erythroid-related hematological parameters, with workers of lower or higher BF% and TG more sensitive to benzene-induced elevation of MCHC (Pinteraction = 0.021) and benzene-induced decrease of HCT (Pinteraction = 0.050), respectively. We also found that some erythroid-related hematologic parameters differed between subgroups of workers with different SPMA levels and fat content combination. CONCLUSIONS: Our study suggested that benzene exposure, fat content, and their interactions may affect erythroid-related hematological parameters in petrochemical workers in a complex manner that are worthy of further investigation.

SO2 Electrocatalytic Oxidation Properties of Pt-Ru/C Bimetallic Catalysts with Different Nanostructures.

Electrocatalytic oxidation of SO2 has been applied in many fields, and electrocatalyst is the focus of the research. Platinum-based electrocatalysts are the hot spot in this reaction. Although the properties of these materials have been optimized to a certain extent, there is still room for improvement in activity and long-term durability. In light of this, two kinds of carbon-supported Pt-Ru bimetallic electrocatalysts (PtRu/C alloy catalyst and Ru@Pt/C core-shell catalyst) were prepared by the microwave reduction method. The experiments demonstrate that the enhancement in the activity of bimetallic catalysts originates from the electronic effect and bifunctional effect between Pt and Ru. Bimetallic catalyst contains a large number of RuOxHy, which promotes the reaction. Because of the high Pt utilization, Ru@Pt/C catalyst with the Pt shell has a higher performance than alloy catalyst. The unit Pt mass activity of PtRu/C and Ru@Pt/C is 1.73 and 2.43 times that of Pt/C, respectively. Ru@Pt/C exhibits excellent stability in the high acid environment and is a promising SO2 electrocatalyst.

High-Performance Pt Catalyst with Graphene/Carbon Black as a Hybrid Support for SO2 Electrocatalytic Oxidation.

In the electrochemical Bunsen reaction, which is the key reaction of the sulfur-iodide cycle, the main overpotential corresponds to the oxidation of SO2. The catalysts currently used for the liquid phase electrocatalytic oxidation of SO2 are mainly based on noble metals, which have excellent corrosion resistance and catalytic activity in an acidic environment. To improve the performance of the commercial Pt catalyst, a Pt catalyst with reduced graphene oxide (RGO) and carbon black as a hybrid support was synthesized by the microwave-assisted polyol reduction process. The large two-dimensional planar structure of RGO was a better anchor for Pt nanoparticles, and a catalyst with fine and uniform distribution of Pt particles was obtained. The carbon black interior prevented the agglomeration of RGO, forming a stereoscopic catalyst structure. The electrochemical test results showed that the RGO/carbon black hybrid support catalyst possessed a higher electrocatalytic activity than the single support catalysts and could be used as an efficient and stable catalyst for the SO2 electrolyzer.

Regulating low-NOx and high-burnout deep-air-staging combustion under real-furnace conditions in a 600 MWe down-fired supercritical boiler by strengthening the staged-air effect.

A 600 MW(e) down-fired pulverized-coal supercritical boiler, which was equipped with a deep-air-staging combustion system for reducing the particularly high NOx emissions, suffered from the well-accepted contradiction between low NOx emissions and high carbon in fly ash, in addition to excessively high gas temperatures in the hopper that jeopardized the boiler's safe operations. Previous results uncovered that under low-NOx conditions, strengthening the staged-air effect by decreasing the staged-air angle and simultaneously increasing the staged-air damper opening alleviated the aforementioned problems to some extent. To establish low-NOx and high-burnout circumstances and control the aforementioned hopper temperatures, a further staged-air retrofit with horizontally redirecting staged air through an enlarged staged-air slot area was performed to greatly strengthen the staged-air effect. Full-load industrial-size measurements were performed to confirm the availability of this retrofit. The present data were compared with those published results before the retrofit. High NOx emissions, low carbon in fly ah, and high hopper temperatures (i.e., levels of 1036 mg/m(3) at 6% O2, 3.72%, and about 1300 °C, respectively) appeared under the original conditions with the staged-air angle of 45° and without overfire air (OFA) application. Applying OFA and reducing the angle to 20° achieved an apparent NOx reduction and a moderate hopper temperature decrease while a sharp increase in carbon in fly ash (i.e., levels of 878 mg/m(3) at 6% O2, about 1200 °C, and 9.81%, respectively). Fortunately, the present staged-air retrofit was confirmed to be applicable in regulating low-NOx, high-burnout, and low hopper temperature circumstances (i.e., levels of 867 mg/m(3) at 6% O2, 5.40%, and about 1100 °C, respectively).