Size-controlled growth of ZnSe nanocrystals for high-performance photocatalytic H2O2 production in pure water.

Semiconductor photocatalysis is deemed as a novel and promising process that can produce H2O2 from earth-abundant water and gaseous dioxygen using sunlight as the energy supply. The searching of novel catalysts for photocatalytic H2O2 production has received increasing attention in the last few years. Herein, size-controlled growth of ZnSe nanocrystals was realized via a solvothermal method by varying the amount of Se and KBH4. The performance of the as-obtained ZnSe nanocrystals towards photocatalytic H2O2 production depends on the mean size of the synthesized nanocrystals. Under O2-bubbling, the optimal ZnSe sample presented an excellent H2O2 production efficiency (8.596 mmol g-1 h-1), and the apparent quantum efficiency for H2O2 production reaches as high as 2.84% at λ = 420 nm. Under air-bubbling, the accumulation of H2O2 was as high as 1.758 mmol L-1 after 3 h irradiation at the ZnSe dosage of 0.4 g L-1. The photocatalytic H2O2 production performance is far superior to the most investigated semiconductors such as TiO2, g-C3N4, and ZnS.

Tracking long-term population exposure risks to PM2.5 and ozone in urban agglomerations of China 2015-2021.

China has experienced severe air pollution in the past decade, especially PM2.5 and emerging ozone pollution recently. In this study, we comprehensively analyzed long-term population exposure risks to PM2.5 and ozone in urban agglomerations of China during 2015-2021 regarding two-stage clean-air actions based on the Ministry of Ecology and the Environment (MEE) air monitoring network. Overall, the ratio of the population living in the regions exceeding the Chinese National Ambient Air Quality Standard (35 µg/m3) decreases by 29.9 % for PM2.5 from 2015 to 2021, driven by high proportions in the Middle Plain (MP, 42.3 %) and Lan-Xi (35.0 %) regions. However, this ratio almost remains unchanged for ozone and even increases by 1.5 % in the MP region. As expected, the improved air quality leads to 234.7 × 103 avoided premature mortality (ΔMort), mainly ascribed to the reduction in PM2.5 concentration. COVID-19 pandemic may influence the annual variation of PM2.5-related ΔMort as it affects the shape of the population exposure curve to become much steeper. Although all eleven urban agglomerations share stroke (43.6 %) and ischaemic heart disease (IHD, 30.1 %) as the two largest contributors to total ΔMort, cause-specific ΔMort is highly regional heterogeneous, in which ozone-related ΔMort is significantly higher (21 %) in the Tibet region than other urban agglomeration. Despite ozone-related ΔMort being one order of magnitude lower than PM2.5-related ΔMort from 2015 to 2021, ozone-related ΔMort is predicted to increase in major urban agglomerations initially along with a continuous decline for PM2.5-related ΔMort from 2020 to 2060, highlighting the importance of ozone control. Coordinated controls of PM2.5 and O3 are warranted for reducing health burdens in China during achieving carbon neutrality.

The Mechanism and Kinetics Model of Degradation of Dicarboxylic Acids by Hydroxyl Radicals under Atmospheric Conditions.

The atmospheric degradation mechanism of dicarboxylic acids (DCAs) initiated by hydroxyl radicals has been theoretically investigated at the DLPNO-CCSD(T)/def2-TZVP//BH&HLYP/6-311++G(d,p) level of theory. In the presence of O2, the degradation of DCAs by hydroxyl radicals takes place through a two-step mechanism: the α-H elimination and the degradation of the peroxyl radical intermediate. The latter degradation mechanism is easy to proceed for the exothermic process of radical recombination. Therefore, the degradation rate of DCAs is determined by an α-H elimination step, which is accelerated in the case of long carbon-chain DCAs with a lower energy barrier. Canonical variational transition state theory has been employed to estimate the rate constants of the H-elimination step of the DCA degradation reaction by hydroxyl radicals over the temperature range of 220-1000 K.

Application of an environmental multimedia modeling system for health risk assessment: Key influencing factors and uncertainties research.

In this paper, an environmental multimedia modeling system (EMMS) that combines a risk assessment with a Monte Carlo method (MCM) was used to explore the interaction between groundwater and surface water with respect to chemical exposure and risk. The EMMS-MCM simulations incorporated several key influencing factors that are inherent in traditional predictions of subsurface and surface-water interactions, including soil permeability coefficients and parameters such as hydraulic conductivity, density, recharge, layers, and depth. These influencing factors are generally associated with the largest sources of uncertainty in modeling and pose significant challenges to water management and to the optimal allocation of water resources. A case study involving benzene at the Trail Road landfill site located in the Ottawa-Carlton area of Canada is presented to illustrate the use of the EMMS-MCM approach. The model results are verified by comparisons to the results of groundwater and surface-water investigations in the landfill. The EMMS-MCM results are evaluated using a risk quotient (RQ) risk assessment method to quantify environmental risk. The EMMS-MCM simulations can be used to support hazardous field work and contribute to environmental management by predicting the possible consequences of hazardous chemical contaminations in surface waters and groundwater. The integration of the EMMS-MCM and RQ approaches represents an appropriate tool for the accurate assessment of long-term pollutant risks and environmental management of surface- and groundwater resources. Integr Environ Assess Manag 2021;17:877-886. © 2021 SETAC.

Discovering Correlations between the COVID-19 Epidemic Spread and Climate.

The outbreak of Corona Virus Disease 2019 (COVID-19) has affected the lives of people all over the world. It is particularly urgent and important to analyze the epidemic spreading law and support the implementation of epidemic prevention measures. It is found that there is a moderate to high correlations between the number of newly diagnosed cases per day and temperature and relative humidity in countries with more than 10,000 confirmed cases worldwide. In this paper, the correlation between temperature/relative humidity and the number of newly diagnosed cases is obvious. Governments can adjust the epidemic prevention measures according to climate change, which will more effectively control the spread of COVID-19.

Performance of desulfurization ash for the preparation of grouting fire prevention material.

The accumulation of desulfurization ash from coal-fired power plants can lead to serious waste of land resources and environmental safety problems. This work presents an experimental study on the feasibility of recycling original desulfurization ash as the main raw materials, and a new green grouting material was prepared. The results indicate that a desulfurization ash-based grouting fire prevention material which was prepared according to the following ingredient design (a water-to-solid ratio of 1.0:1 and a hydroxyethyl cellulose content of 0.09% desulfurization ash, 12% quicklime, 0.6% Na2SO4, and 0.05% triethanolamine, 80 °C curing). The slurry's viscosity meets requirements, and its suspension, liquidity, and consolidation strength are better than those of clay under the same conditions. In addition, the grouting material's inhibitor ratio is increased with temperature increase, which means it has good flame retardancy. Environmental performance tests concluded that when desulfurization ash as-recycled admixture is used for the preparation of grouting fire prevention material, from the technique point of view, the environmental safety of them is very good.

An effective treatment method for shale gas drilling cuttings solidified body.

The exploration and production of shale gas technology provides a way for utilization of clean fuels. However, during the exploration process of shale gas, enormous amount of drilling cutting was generated and had to be solidified and landfilled. So the accumulation of shale gas drilling cutting solidified body (SGDS)causes severe land resource misuse and environmental complications. This study focuses on the utilization of SGDS as a raw material for the production of cement clinker, and the phase composition, microstructure, and environmental performance of the cement clinker was investigated by X-ray powder diffraction (XRD), scanning electronic microscopy (SEM), energy-dispersive X-ray spectrum analysis (EDX), and soaking test, respectively. The results show that the cement clinker obtained mainly constitutes of typical Portland cement mineral (C3S, C2S, C3A, and C4AF). The leaching test indicated that the concentration of heavy metal ions in leachate is within the limits allowed by the state "Technical specification for co-processing of solid wastes in cement kiln" (GB 30760-2014). This study therefore provides a benchmark on environmental effects resulting from drilling cuttings and utilization of resources.

Characterization of water soluble inorganic ions and their evolution processes during PM2.5 pollution episodes in a small city in southwest China.

PM2.5 samples were collected in four segregate one-month periods, each representing one season, for analyzing their contents of water soluble inorganic ions (WSIIs) in a small city inside Sichuan Basin. Daily PM2.5 concentrations ranged from 23.2 to 203.1 µg m-3 with an annual mean of 66.9 ±â€¯33.6 µg m-3. Annual mean concentrations of WSIIs was 28.8 ±â€¯20.3 µg m-3, accounting for 43.1% of PM2.5. Seasonal mean concentrations of WSIIs ranged from 17.5 ±â€¯9.3 µg m-3 in summer to 46.5 ±â€¯27.6 µg m-3 in winter. Annual mean mass ratio of NO3-/SO42- was 0.49, demonstrating predominant stationary sources for secondary inorganic aerosols (SNA, including SO42-, NH4+ and NO3-); whereas annual mean molar ratio of [NH4+]/[NO3-] was 3.5, suggesting dominant agriculture emissions contributing to the total nitrogen. During a severe and long-lasting (13 days) winter pollution period when mean PM2.5 concentration reached to 132.5 µg m-3, PM2.5 concentration was enhanced by a factor of 2.6 while that of SNA by a factor of 2.9 compared to those before the pollution event, and the fraction of SNA in PM2.5 only increased slightly (from 46.7% to 50.6%). Thus, local accumulation of pollutants under poor diffusion conditions played a major role causing the extremely high PM2.5 concentration, besides the contributions from the enhanced SNA formation under specific weather conditions.

Enhancer assisted-phytoremediation of mercury-contaminated soils by Oxalis corniculata L., and rhizosphere microorganism distribution of Oxalis corniculata L.

The present study investigated remediation of mercury-contaminated soils using Oxalis corniculata L. combined with various enhancers (sodium thiosulfate, ammonium thiosulfate, ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid). The experiment was conducted using Oxalis corniculata seedlings planted in pots containing mercury loaded soils. Investigations included analysis of soil properties, plant growth conditions, ability of the plants to accumulate and extract mercury, and rhizosphere microorganism distribution. The maximal mercury content of the aerial parts and the mercury-translocation ratio of Oxalis corniculata treated with enhancers increased compared to Oxalis corniculata without enhancers. Compared with no enhancers, the theoretical reduction in phytoremediation time was about 50%, 25%, 20% and 21% when Oxalis corniculata was treated with sodium thiosulfate (Na2S2O3), ammonium thiosulfate ((NH4)2S2O3), ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA), respectively. The results indicated that the dominant species in rhizosphere soils varied with different enhancers. However, the evenness of background soils, rhizosphere soils of Oxalis corniculata, Oxalis corniculata treated with Na2S2O3, (NH4)2S2O3, EDTA and DTPA was not largely different at 0.62, 0.61, 0.57, 0.64, 0.61 and 0.63, respectively. These findings demonstrate that Oxalis corniculata treated with Na2S2O3 has the potential to recover and reclaim mercury-contaminated soils in pots.

Effects of growth agents and mercury on several herbs.

The paper discussed the effects of growth agents and mercury on the growth of four herb species subjected to a pot experiment: Aloe vera, Setcreasea purpurea, Chlorophytum comosum, and Oxalis corniculata. We determined the height and biomass production of selected plants treated with different growth agents and different concentrations of mercury solutions. We evaluated the relative growth rate (RGR) of the experimental plants. The aim of the study was to explore potential novel solutions to the shortcoming of the low speed of phytoremediation. The results showed that the upper parts of Aloe vera and Chlorophytum comosum had the fastest growth in the treatment with water only. In contrast, the upper parts of Setcreasea purpurea grew most intensely after the treatment with Lvyebao Fertilizer, whereas the aboveground parts of Oxalis corniculata had the fastest growth after the application of water and the occasional use of Green Cake Fertilizer. In addition, the tolerance to mercury of Oxalis corniculata was the strongest, whereas that of Chlorophytum comosum was the lowest among the species investigated.

Photodegradation of 17beta-estradiol in water by UV-vis/Fe(III)/H2O2 system.

Photodegradation of 17beta-estradiol (E2) in aqueous solutions by UV-vis/Fe(III)/H(2)O(2) system, namely Photo-Fenton system, was preliminarily investigated under a 250 W metal halide lamp (lambda > or = 313 nm). The influences of initial pH value, initial concentration of H(2)O(2) and E2 on photodegradation efficiency of E2 were discussed and the amount of CO(2) produced by the photodegradation reaction was measured. The results indicates that E2 could be decomposed efficiently in UV-vis/Fe(III)/H(2)O(2) system. Under the condition of 10.0 micromol L(-1) Fe(III), 1000 micromol L(-1) H(2)O(2) and pH 3.0, the degradation efficiency of 18.4 micromol L(-1) E2 reach 75.2% after the irradiation of 160 min. Over the range of pH 3.0-6.0, the higher acidity, the higher the degradation efficiency of E2 and initial reaction rate are. The degradation efficiency of E2 increases with increasing of initial concentration of H(2)O(2) and with decreasing of initial concentration of E2. The E2 mineralization efficiency increases with reaction time but the mineralization efficiency was lower. When the initial concentration of Fe(III) and H(2)O(2) were 10.0 and 1000 micromol L(-1), respectively, the mineralization efficiency of 18.4 micromol L(-1) E2 solution with pH 3.0 was only 21.6% after 160 min irradiation. It is suggested that the mineralization occurred probably only at aromatic ring.

Degradation of estrone in aqueous solution by photo-Fenton system.

Photodegradation of estrone (E1) in aqueous solutions by UV-VIS/Fe(III)/H2O2 system (photo-Fenton system) was preliminarily investigated under a 250-W metal halide lamp (lambda > or = 313 nm). The influences such as initial pH value, initial concentration of Fe(III), H2O2 and E1 on degradation efficiency of E1 were discussed in detail. The results indicated that E1 could be decomposed efficiently in UV-VIS/Fe(III)/H2O2 system. After 160-min irradiation, the photodegradation efficiency of 18.5 micromol L(-1) E1 reached 98.4% in the solution containing 20.8 micromol L(-1) Fe(III), and 1664 micromol L(-1) H2O2 at initial pH value 3.0. The degradation efficiencies of E1 were dependent on initial pH value, Fe (III) concentration and H2O2 concentration. The degradation of four estrogens estrone (E1), estradiol (E2), 17alpha-ethynylestradiol (EE2) and diethylstibestrol (DES) in UV-VIS/Fe(III)/H2O2 system were also conducted. Under the conditions of pH 3.0, the E1 apparent kinetics equation -dC(E1)/dt=0.00093[H2O2]0.47[Fe(III)]0.63[E1]0.24 (r=0.9935, n=11) was obtained. The E1 mineralization efficiency was lower than degradation efficiency under the same conditions, which implied the mineralization occurred probably only at aromatic ring. There are several intermediate products produced during the course of E1 degradation. The comparison of the degradation efficiencies of E1, E2, EE2 and DES degradation in UV-VIS/Fe(III)/H2O2 system were also conducted, and the relative degradability among different estrogens were followed the sequence: DES>E2>EE2>E1.