2019 Vol. 38, No. 4
PM10 samples were collected concurrently at five sites:two urban sites (the east gate of China University of Geosciences (CUGB)and the roof of a testing building within CUGB), two industrial sites (coking plant of Capital Steel Plant and a thermoelectric plant) and a background site (Ming Tombs) in Beijing China in winter. The concentration and spatial distribution of 17 polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) congeners were analyzed with isotope dilution and high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS) based on US EPA 1613B method. PM10 concentrations were in the range of 140-264 μg·m-3 with a mean value of 184 μg·m-3, which was 23% higher than the second class daily average standard (150 μg·m-3). ∑17PCDD/Fs concentrations varied from 1.96-4.80 pg·m-3, with an average concentration of 3.69 pg·m-3. The toxic equivalents (TEQs) varied from 148-353 fg I-TEQ·m-3 with an average value of 271 fg I-TEQ·m-3. The highest PCDD/Fs pollution level was observed at the industrial sites, followed by urban sites and background site in Beijing.
To investigate the influence of firecrackers and the winter meteorological conditions on PM1, samples of atmospheric PM1 in suburban Chengdu were collected during February 1st to 28th, 2015 and their chemical components were analyzed. Results showed that during the whole sampling period, the average mass concentration of the atmospheric PM1 was 76.67 μg·m-3, 19.9% of which was inorganic elements. It was noted that the inorganic elements accounted for 12% in the period of February 1st -17th, and 28% in the period of February 18th-28th, indicating that the firecrackers contributed to the inorganic elements in the atmospheric PM1. The heavy pollution process in the period of February 9th -14th showed that 500 hPa at high altitude was controlled by the weak high pressure ridges, and the situation at high altitude was stable. The heavy pollution process also showed that the high temperature (8℃) at 850 hPa played an important role in the formation and maintenance of inversion layer, and there was no significant pressure change in the Sichuan Basin, which was not conducive to the diffusion of pollutants. Analysis of the backward trajectory revealed that the accumulation of PM1 at suburban Chengdu city was associated with low air masses from the southeast and northeast.
To investigate the pollution characteristics of water-soluble ions in the ambient PM10 and PM2.5 in Heze, 120 samples were collected at six sites from August 13 to 23, 2015. The water-soluble ions (SO42-,NO3-,NH4+,Cl-,Ca2+,K+,Na+,Mg2+,F-) in particulate matter samples were determined using ion chromatography. Meteorological parameters and the concentrations of gaseous pollutants at the sampling sites were obtained synchronously. The results indicated that the mean concentrations of PM10 and PM2.5 during the summer were up to 94.5 and 55.2 μg·m-3, respectively, which was lower than some domestic cities. This may be affected by factors such as economic development, industrial energy structure, meteorological conditions and so on. The range of PM2.5/PM10 ratio was 0.5 to 0.8, suggesting the fine particles pollution in Heze was more serious during the summer. The concentrations of the total WSIs in PM10 and PM2.5 are 30.5 μg·m-3 and 17.0 μg·m-3, accounting for 32.4% and 29.6% in PM10 and PM2.5, respectively. The dominating WSIs are SO42-, NO3- and NH4+, which account for 84.3% of the total WSIs in PM10 and 88.3% of the total WSIs in PM2.5, respectively. SO42-,NO3-,NH4+ and K+ are mainly concentrated in the fine particles (PM2.5),Ca2+ and Mg2+ are mainly concentrated in the coarse particles (PM10). There are significantly spatial heterogeneity among the concentrations of SO42-, NO3-, NH4+, Ca2+ and Mg2+ in ambient PM10 and PM2.5 at each sampling site. The strong correlation of SO42-, NO3- and NH4+ shows main existence from them are NH4HSO4, NH4NO3. In addition, the average ratio of NO3-/SO42- is up to 0.46 in PM10 and 0.42 in PM2.5, respectively, indicating that the combustion is major contributor to the particulate matter in Heze during summer.
Three hundred and sixty PM2.5 samples were collected in locations in Yibin,Sichuan Province, from January 2017 to December 2017. The concentrations of organic carbon (OC) and element carbon (EC) in PM2.5 samples were determined by DRI Model 2001 Thermo/Optical Carbon Analyzer. The secondary organic carbon(SOC)was then estimated by the OC/EC ratio. The results showed that the annual average concentration of PM2.5 in Yibin was 75.2 μg·m-3. The annual average concentrations of OC and EC were 14.3 μg·m-3 and 4.30 μg·m-3, respectively. Also, the OC and EC concentrations showed a seasonal variation in an order of winter > autumn > spring > summer. OC accounted for 19.0% of PM2.5, which was an important part of PM2.5. Annual average concentration of SOC was 4.70 μg·m-3, accounting for 29.3% of total OC. Note that the proportion of SOC in OC followed the order of spring > winter ≈ autumn > summer. Further principal component analysis (PCA) of OC1, OC2, OC3, OC4, EC1, EC2, EC3 and OPC showed that motor vehicle exhaust, coal-fired emissions and biomass burning were the main sources of OC and EC in PM2.5 in Yibin, contributing 54.0%-69.0% of the carbonaceous aerosol in PM2.5.
As a group of persistent organic pollutants, dioxins have drawn much attention because of their hightoxicity and bioaccumulation potency. In order to reduce the adverse effect of dioxins on the ecological environment, it is important to investigate the sources and formation mechanisms of dioxins in the environment. The incineration of solid waste is one of the main sources of dioxins. In this paper the concentration of dioxins formed during the solid waste incineration process was reviewed, and the influencing parameters on dioxin formation was analyzed. The reaction pathways of dioxin formation from the combustion of typical dioxin precursors were also systemically elaborated, based on the application of quantum chemistry on the dioxin formation mechanisms studies in recent years. Further study on the effect of dioxins produced by solid waste incineration to the surrounding environment was proposed as well.
This paper took a domestic waste landfill site in Guangzhou as the study site. According to the current pollution control standards of domestic waste landfill sites and the ambient air and groundwater quality standards, the pollution status of air and groundwater in the landfill was analyzed by monitoring the relevant indicators of air and groundwater in the area and surrounding sensitive points. The results showed that wind direction is the main factor affecting the surrounding air pollution. The levels of hydrogen sulfide and odors in downwind were higher than those in the upper wind direction. Air pollution was more serious in the season of high temperature, humidity and low wind speed. Leachate and groundwater were the most important factors affecting groundwater. At upstream locations, the monitoring factors of groundwater were within the standard range. But at the downstream, the total Escherichia coli, ammonia nitrogen, manganese, nitrite and oxygen consumption exceeded the category Ⅲ of groundwater quality standard, and reached the level of serious pollution. The correlation coefficient of all the monitoring wells is more than 0.99, and the correlation with the background well is very small, which indicates that the pollution of monitoring well was caused by the leachate. The principal component analysis showed that the pollution factors mainly came from three different sources of pollution. Lead and manganese, nitrite, Escherichia coli, ammonia nitrogen and oxygen consumption came from different sources respectively. The pollution factors of groundwater may be related to the composition of landfill waste.
Catering source is an important source of urban atmospheric fine particulate PM2.5, In order to understand the characteristics and sources of PM2.5 emission from catering sources, the concentrations of PM2.5 and organic pollutants on PM2.5 from two different types of catering sources, outdoor barbecue and canteen, were measured. The main pollutants detected by gas chromatography-mass spectrometry (GC/MS) were alkanes, acids, aldehydes, ketones, esters, olefins, polycyclic aromatic hydrocarbons and other organic pollutants. The sources of pollutants were compared with the atmospheric control samples. The contrast results showed that the concentration of PM2.5 in outdoor barbecue samples was 905.6±160.9 μg·m-3, the concentration of PM2.5 in canteen samples was 343.9±30.6 μg·m-3, and the concentration of PM2.5 in atmospheric control samples was 76.7±1.7 μg·m-3. The PM2.5 concentration from outdoor barbecue was the 2-3.4 times of the PM2.5 concentration from the canteen, and was 9.5-13.6 times of the PM2.5 concentration from ambient air. Oganic acids (47.29%) and aldehydes and ketones (12.97%) were the main organic compounds in PM2.5 emitted from barbecue lampblack. In addition to alkanes (45.2%), fatty acids (11.76%) and aldehydes and ketones (8.84%) in the smoke samples from campus canteens also emitted significantly. Fatty acids may be produced by burning animal fat, while aldehydes and ketones may be derived from flavors and other food additives at high temperature. A small amount of aldehydes and ketones were detected in the atmospheric control samples, but no acids were detected. It is speculated that aldehydes, ketones and acids may be the typical pollutants discharged from cooking fumes.
Fault related soil gas is an important geochemical method to reveal fault properties and tectonic activities, and it is also used to study the impact of fault degassing on the environment. In this paper, the concentration and distribution characteristics of soil gas Rn, CO2 and Hg were obtained in spring, summer and autumn in Mianning area of the Anninghe fault zone. The results showed that the underground gas Rn, CO2 and Hg in the Mianning area of the Anninghe fault zone was heterogeneous. There were three soil gas concentration abnormal sections along the soil gas survey line from west to east, which might reveal the locations of three major fracture zones of the Anninghe fault zone. The concentrations of soil gas CO2 and Hg varied in seasons, and were probably controlled by temperature and rainfall, showing the seasonal effects. Protective measures should be taken in areas with high concentrations of Rn, CO2 and Hg. The results provided a geochemical reference for analyzing the characteristic of gas released from the fault zone and its impact on the environment and human life.
Studies on the changes in spatial pattern of landscape ecological risk on karst plateau zone play important roles in establishing the ecological risk warning mechanisms, minimizing the risk of ecological environment and optimizing the landscape pattern of karst plateau zone. Based on the high-resolution remote sensing images obtained in 2009,2014 and 2017, this work constructed an evolution model of landscape ecological risk pattern to analyze the temporal and spatial changes and spatial mode of landscape ecological risk on Caohai watershed. The results showed that the landscape structure in the study area significantly changed during 2009 to 2017. The areas of cultivated land and shrub land showed a decreasing trend, while the areas of forest land, marsh land, construction land and waters showed an increasing trend. During 2009 to 2017, high ecological risk and relatively high ecological risk were mainly distributed in the north and northeast of the watershed. Moderate ecological risk was mainly distributed in the eastern and southwestern of the watershed. Relatively low ecological risks was mainly distributed in the south-west-northwest of the watershed and low ecological risks was mainly concentrated around the lake area of the watershed. During 2009 to 2017, the ecological risks of the study area were at low and extremely low level, which accountd for more than 72.38% of the study area. During 2009 to 2014, the area of high ecological risk, relatively high ecological risk and moderate ecological risk increased to some extent, but they significantly decreased during 2014 to 2017. There was significant spatial positive correlation between the landscape ecological risks of the watershed during 2009 to 2017, the "high-high" and "low-low" accumulations were the main ecological risk accumulation mode, the "low-high" or "high-low" scattered distribution.
Quality of soil environment in urban parks has a potential impact on the urban environment quality and human health. Studies on soil heavy metals content in China parks and conducting the ecological risk assessment and health risk assessment are beneficial to understand urban environmental quality and control the harm of heavy metals to human body. The research was carried out by US EPA Health Risk Assessment Model and the geo-accumulation index method based on 9 heavy metal concentration in soil samples from 38 parks in 25 Provinces in China. The results showed that the average contents of Cr, Cu, Mn, Ni, Pb, Zn, As, Cd and Hg in the soil were 66.02, 39.47, 498.65, 24.97, 48.11, 148.32, 12.82, 0.67 and 0.26 mg·kg-1, respectively. Their concentration except Mn and Ni, which were higher than the soil background value of China, and had different degrees of accumulation. The health risk assessment results showed that the average daily exposure dose ranking of children and adults in the three pathways was Mn > Zn > Pb > Cu > Cr > Ni > As > Hg > Cd; and the carcinogenic risk sequence of children and adults was As > Cr > Ni > Cd. The carcinogenic risk index of heavy metals in soil, except As, is lower than the carcinogenic risk range. Generally speaking, the content of heavy metals in park soil and urban soil is roughly the same, people should pay attention to the potential health risks when they visit in the park.
Soils of cultivated land and main grain crops (corn and wheat) in three typical mining areas were investigated in order to fully understand the heavy metal contamination of soils and plants around coal mining areas of Yuzhou City. Heavy metal concentrations were measured by inductively coupled plasma-mass spectrometry. Soil quality was assessed using the single-factor pollution index and the Nemero comprehensive pollution index, and the potential health risks to adults and children induced by the intake of heavy metals through crop consumption were evaluated using the hazard quotient. It was found that the farmlands in the study areas were contaminated by heavy metals, and the most polluted farmland was wheat fields followed by corn fields. The heavy metal concentrations ranked as Cd > Cu > Co > Ni > Zn > Cr. The Nemero index of wheat fields was higher than the threshold value of heavy pollution and also higher than that of corn fields. Cd contributed most to the Nemero index. The average concentrations of Cr, Co, Ni, Cu, Zn and Cd were 25.03, 0.54, 2.87, 21.52, 118.68 and 1.97 mg·kg-1 respectively in corn, and 1.04, 0.11, 1.17, 9.55, 61.51 and 0.06 mg·kg-1, respectively, in wheat. The order of concentration coefficient of Cr, Co, Ni, Cu, Zn and Cd was corn > wheat. High risk of metal pollution was found in the grains of corn products near the mining areas, especially Cd. The calculated critical threshold in soil for adults was higher than that for children. The order of individual risk index for the health of children and adults was Co > Cd > Cu > Zn > Ni > Cr, in which Co and Cd had especially high risks for adults, and Co, Cu, Zn, Cd had especially high risks for children. No positive correlations were observed between farmlands and crops.
The occurrence and distribution of different forms of iron in sediments with diverse hydrologic condition of Caohai wetland, Guizhou, were studied by Tessier five step continuous extraction method. The results showed that the iron content in sediments of Caohai wetland was in the range of 22.8-46.2 g·kg-1, and the average content was 37.06 g·kg-1, the iron content decreasd with the increase of water depth. The iron content of each form in sediments from Caohai were in the order of RES-Fe(7.16-41.22 g·kg-1)> OM-Fe(1.68-13.94 g·kg-1)>RED-Fe(2.29-6.96 g·kg-1)>CARB-Fe(0.004-0.095 g·kg-1)>EXC-Fe(0.002-0.004 g·kg-1). The response of each form of iron content to the change of water depths was inconsistent, the content of RES-Fe,EXC-Fe and Tot-Fe decreased as the depth of water deepened, but the content of RED-Fe and OM-Fe increased with the depth of the water, and no obvious change in the content of CARB-Fe were observed. The hydrological conditions affected the iron composition, the samples from S1 and S2 of seasonal ponding water had higher iron content, RES-Fe was the mainly component accounting for 87%-91% of the Tot-Fe. However, the iron content of S3 and S4 of deep and flooded water was low, and OM-Fe and RES-Fe were the mainly component accounting for 87%-91% of the Tot-Fe. It could be seen that the distribution of iron content and its speciation in wetland sediments varied with the water depths and the bioavailability of iron varied accordingly. The results indicated that the raise the of water level may be beneficial to enhancing the bioavailability of iron.
In order to explore the sorption behavior of phenanthrene (PHE) on engineered Al2O3 nanoparticles (NPs) and the influence of solution chemistry on PHE sorption, batch experiments were conducted using α-Al2O3 and γ-Al2O3 NPs under different solution pH, salinity, and heavy metal ion (Ni2+) concentrations. The results indicated that these two types of Al2O3 NPs possessed sorption capability for PHE. The sorption data fit the Freundlich model well, with lgKF of 1.15 and 1.07 for α-Al2O3 NPs and γ-Al2O3 NPs, respectively. Sorption isotherm on α-Al2O3 NPs was linear (n=0.96±0.03), indicating PHE partitioning into the vicinal water layer of the sorbent; while PHE sorption on γ-Al2O3 NPs was nonlinear (n=1.19±0.01), possibly because of the involvment of pore filling besides partitioning mechanism. Sorption on the two NPs was also influenced by the extent NPs aggregation. Sorption under acid and basic conditions was higher than that under neutral condition. When pH was low, the electrostatic attraction dominated PHE sorption onto Al2O3 NPs. When pH was high, the net charge of NPs increased, resulting in less aggregation and greater available surface area of NPs. The lgKF increased from 1.15 to 1.60 (for α-Al2O3NPs) and 1.07 to 2.12 (for γ-Al2O3NPs) as the salinity increased to 32‰. This can be attributed to the salt-out effect. The coexistence of Ni2+ facilitated PHE sorption, which could be due to the increase of surface potential of Al2O3 NPs and the cation-π interaction.
Five different types of biochar were applied to mercury contaminated soil to investigate their impacts on the available mercury in soil. Meanwhile, the adsorption kinetics, adsorption isotherms of mercury ions on biochar and the change of Fourier transform infrared (FTIR) spectra were also investigated in an attempt to understand the adsorption mechanisms of Hg by biochar. The results showed that the available mercury in soil decreased significantly and the ratio reached 77.5%-87.1% after addition of biochar in the soil. The difference of FTIR spectra of biochar before and after the adsorption indicated that hydroxyl group, carboxyl group and amides group may be the major adsorptive sites for Hg(Ⅱ) on the surface of the biochar. In most cases, the adsorption of Hg(Ⅱ) by biochar reached balance within 150 mins and the adsorption was mainly through chemical adsorption, and it fits pseudo-second-order model.
Release behaviors of mercury during thermal treatment of three coal gangues sampled in Shanxi were studied at 150-1000℃ in a quartz tube fixed-bed reactor. Effect of temperature (150-1000℃), atmosphere (N2, 3%O2+N2, CO2), oxygen volume fraction (3%, 9%, 15%, 21%) on the release of mercury were investigated. The result indicated that temperature was the most significant factor of Hg release in coal gangues. The temperature scope of Hg releases was 200-600℃ and the release ratios of Hg were about 92% under different conditions. There are two releasing peaks during the whole temperature range of Hg release at the temperature range of 200-400℃ and 400-600℃, respectively. And the maximum release of Hg in the middle temperature releasing range occurd at 500℃ for the three coal gangues. The results also illustrated that micro oxygen atmosphere promoted the release of Hg while the dioxide restrains the release of Hg in the low temperature range (200-400℃) and improved the release during the middle temperature range (400-600℃). The ability of Hg and volatility releasing rised as the oxygen volume fraction increasing in turn.
Methylsiloxanes have huge production and consumption. As a new class of pollutants in the global environment, some methylsiloxanes have been restricted in industrial production. The homologues of methylsiloxane are abundant. They exist in a variety of matrixes with large differences in content. To better represent the pollution levels of methylsiloxanes and assess their possible risk to the environment and human health, it is necessary to establish the accurate, sensitive and efficient analysis methods. In this review, pretreatments and analysis methods of methylsiloxanes in multiple sample matrixes were systematically summarized. The pros and cons of different methods were compared, and the problems that should be paid special attention to in analysis procedures were put forward. The prospect of further research direction is also included.
Planar optodes have advantages of in-situ, real-time, high-resolution and multi-temporal-scale quantitative measurement. It has a wide range of application prospects in the research areas of biomedicine, marine science, environmental science, and plant nutrition. This article reviews the principles of planar optodes, the development of fluorescent dyes in the past two decades, the development of imaging methods, and their applications in the environmental science research. Challenges of the current planar optode technique were summarized and a perspective for future development of the technique was provided as well.
Mercury adsorbent bio-chars prepared in N2 were investigated. The pyrolysis characteristics, pore structures and functional groups of the bio-chars were characterized. The two-dimensional molecular structure of bio-char was built by ChemBioOffice in combination with the chemical structure obtained. The results showed that the pyrolysis process of biomass could be divided into three stages. The pore structures of bio-char were well developed. There were abundant functional groups on the surface of bio-char. Aromatic carbon was the main component of the bio-char molecular structure, while aliphatic carbon was linked to aromatic structural units. And the bio-char was a short-range ordered amorphous substance, which contained graphite microcrystalline structures. Based on the characterization results, the molecular structure model was mainly constituted by aromatic structure, including a methyl, 4 hydroxyls and 8 carbonyls. The molecular formula was C55H37NO14, Mr=935. The model was verified. Based on the molecular mechanics, the three-dimensional molecular structure was optimized in the UFF, Dreiding and MM2 force fields. After the optimization, the total potential energy was the maximum in the UFF force field. The SE method PM6 was also applied to obtain the formation heat of the bio-char molecular in the three force fields. And the molecular was the most stable in the Dreiding force field.
With the same iron content, three types of Fe/ZSM-5 molecular sieve catalysts with different iron sources (ferrous nitrate, ferrous chloride and ferrous sulfate) were prepared by impregnation method. The effects of iron sources on the NH3-SCR performance of Fe/ZSM-5 catalysts were investigated and the physicochemical properties of the samples were characterized by XRD, BET, XPS, H2-TPR and NH3-TPD techniques. The results indicated that iron source had a great influence on the low-temperature (<350℃) NH3-SCR performance of Fe/ZSM-5 catalysts. The order of activity of those catalysts at low temperatures was as follows:Fe(Cl)/ZSM-5 > Fe(S)/ZSM-5 > Fe(N)/ZSM-5. The sample with ferrous chloride as precursor obtained the best NH3-SCR activity, and the NO conversion of Fe(Cl)/ZSM-5 reached 90% at 233℃. Characterization result showed that the Fe(Cl)/ZSM-5 sample possessed the largest amount of isolated Fe3+ species and moderately acidic sites. Isolated Fe3+ species is beneficial to enhance the low temperature reduction performance of the Fe/ZSM-5 catalyst, and moderately acidic sites are favorable for the low-temperature catalytic performance.
High-voltage pulsed discharge synergistic catalyst technology is one of the most promising NOxremoval methods at present. The object of treatment in this paper was NOx, which was removed by a pulsed discharge in conjunction with a perovskite-type catalyst. A citric acid-EDTA Sol-Gel method was employed to prepare LaMnO3 perovskite catalyst. By mixing Fe with the catalyst and by changing the calcination temperatures in the process of catalyst preparation, the effects of the catalyst-co-pulsed discharge on NO conversion, NO2 generation, and NOx removal efficiency under different sets of conditions such as reaction temperatures, catalyst doping amount were analyzed. XRD and SEM were used to characterize the catalysts. The results showed that with increasing amount of Fe added in the catalyst LaMn1-xFexO3, the NO conversion first increased and then gradually went down. With the increase of calcination temperature, the NO conversion rate gradually decreased. With increasing dosage of the catalyst, the NOx removal rate increased and then stabilized. When setting discharge frequency to be 30 Hz, pulse voltage 30 kV, Fe doping amount 0.3, calcination temperature 700℃, dosage of catalyst 1.6 g, and reaction temperature 300℃, the highest NOx removal rate of 62.15% was reached.
Through bubbling with ozone, artificial zeolite with short time and high ammonium adsorption capacity was synthesized from coal fly ash (Z-CFA-ozone). Compared with the normal synthetic product, the corresponding XRD (X-ray Diffraction) patterns indicated the synthetic process of Z-CFA-ozone was accelerated by ozonation, which could save 12 hours. BET (Brunauer-Emmett-Teller) surface area measurement results showed that specific surface area of Z-CFA-ozone was 412.67 m2·g-1, which was almost 40 times larger than that of natural zeolite. Fourier-transformed infrared results revealed that ammonium (NH4+-N) was adsorbed on Z-CFA-ozone by ion-exchange, and the structure of Z-CFA-ozone did not change after bubbling with ozone. Orthogonal tests analysis showed that the order of factors affecting the NH4+-N adsorption capacity of Z-CFA-ozone was ozone concentration, temperature, crystallization time, and pH. The adsorption process fitted well with the pseudo-second-order kinetics model and the Langmuir isotherm model. Thermodynamic study revealed the adsorption process of NH4+-N by Z-CFA-ozone was primarily due to spontaneous endothermic reaction.
Natural enzymes (i.e., peroxidase and phenoloxidase) as green catalysts can catalyze the transformation of phenolic contaminants to form phenoxyl radical intermediates, which subsequently yield the covalent binding products by reactive radical-mediated coupling reactions. It is noteworthy that nano-technology has merged to deliver artificial materials for multi-functional applications. In particular, certain nano-materials possess the enzyme-like catalytic performances and substrate specificities. At present, scientists have confirmed that nano-metallic oxides (N-MOs) have dual identities of the nano-materials and natural enzymes, not only mimick the catalytic activity of natural enzymes in the transformation of phenolic contaminants, but also own the physicochemical properties of nano-materials. They are expected to overcome the disadvantage of natural enzymes (e.g., lack of stability, hard-to-recycle, loss of activity, and high cost), and catalyze the transformation of phenolic contaminants efficiently in aqueous solution. For instance, horse radish peroxidases and laccases have been shown to be capable of coupling phenolic contaminants via reactive radical-mediated covalent coupling mechanisms in water. It is thus expected that nano-enzymes wih peroxidase and/or phenoloxidase like activities have the potential to be used in water/wastewater treatment for phenolic contaminants removal. In this paper, we review the basic performance and catalytic coupling mechanisms of peroxidase and phenoloxidase for the transformation of phenolic contaminants in natural aquatic environments. Moreover, the chromogenic reactions, catalytic activities, and influence factors for N-MOs are comparably evaluated, mainly focusing on the latest advances in the transformation and removal of phenolic contaminants in water. It is aimed at providing new theoretical evidences and guidance for the multi-functional applications of nano-enzymes in natural aquatic environments.
To investigate the influence of zirconium loading on the adsorption of phosphate from aqueous solution on zirconium/magnesium-modified bentonite (ZrMgBT), a series of ZrMgBTs with different levels of zirconium loading were prepared and characterized. Their adsorption properties for phosphate were then comparatively investigated in batch mode in this study. Results showed that high adsorbent dosage was beneficial for the removal of phosphate from water by ZrMgBT. Adsorption kinetics was well fitted by the pseudo-second-order model. The Langmuir, Freundlich and Dubinin-Redushckevich (D-R) isotherm models could be suitably applied to fit the adsorption equilibrium data of phosphate on ZrMgBT. In general, an increase in solution pH from 4 to 9 did not result in the suppression of phosphate removal by ZrMgBT. The phosphate adsorption capacity and initial adsorption rate for ZrMgBT increased with an increase in its zirconium loading amount. However, the ZrO2 content-normalized Qmax for ZrMgBT generally decreased with an increase in its zirconium loading. Results of this work indicate that ZrMgBT is a very promising adsorbent material for phosphate removal from water. The ZrMgBT with a higher zirconium loading amount exhibits a higher phosphate adsorption capacity, while the decrease in the zirconium loading amount of ZrMgBT can increase the utilization efficiency of ZrO2 for phosphate adsorption.
MoO3 nanomaterials were synthesized by hydrothermal method as the precursor of β-Mo2C nanotubes. Then, the Mo-dopamine complex was synthesized by assisted ultrasonic stirring solvent. Finally, β-Mo2C nanotubes were prepared by programmed temperature processing. The nanotubes were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Electrochemical methods such as cyclic voltammetry (CV), square wave pulse voltammetry (SWV), and linear sweep voltammetry (LSV) were used to study the catalytic oxidation of glucose. The experimental results showed that the β-Mo2C nanomaterial possess excellent performance. The impedance of the nanotubes was small, the rate of electrons conduction was fast, and the catalytic effect on the oxidation of glucose was excellent. The open current potential (OCP) of the constructed glucose/O2 fuel cell was 0.47 V, the maximum current density of the fuel cell was 3.0 mA·cm-2, and the power density was 0.70 mW·cm-2.
In this paper, perfluorooctanoic acid (PFOA) was used as the target pollutant. The characteristics and mechanism of humic acid (abbreviated HA) adsorption of PFOA were discussed. The results showed that the adsorption of PFOA on humic acid reached a complete equilibrium after 24 h, and the adsorption kinetics could be better fitted with Lagrange second-order kinetics (R2>0.99). The fitting results of the particle diffusion model indicate that the adsorption of PFOA on humic acid is divided into three processes, in which the internal diffusion of the particles is the main factor leading to adsorption. The adsorption isotherm was fitted with the Liner, Freundlich and Langmuir models. The results showed that the Liner and Freundlich models had better adsorption effects, indicating that hydrophobic partitioning dominates the adsorption of PFOA on HA. pH and ionic strength have a significant effect on adsorption, and adsorption decreased with increasing pH and ionic strength. Hydrophobic partitioning and hydrogen bonding may be the main factors leading to HA adsorption of PFOA. Therefore, the effects of humic acid should be considered when considering the behavior of PFOA in the environment.
Thermocatalytic decomposition is able to completely degrade toxic molecules at the active sites of a catalyst through adsorption, oxidation, dealkylation and hydrolysis to form small molecular compounds such as CO2 by passing the heated toxic air through the catalyst bed, which is a broad-spectrum and efficient purification technology. Hereon, the performance of thermocatalytic decomposition of typical chemical warfare agents on catalysts is reviewed. For the nerve agent sarin, activated carbon, vanadium oxide and Pt catalysts have better catalytic activity. However, the main factor for deactivation is the gradual accumulation of phosphorus species on the catalysts. For the systemic agents HCN and CNCl, the impact of the hydrolysis reaction on product selectivity is particularly important. And for mustard gas, a typical blister agent, the studies on the catalyst design and reaction mechanism are still in the early stage. Compared with other chemical warfare agents, phosgene, a choking agent, is more easily catalyzed and decomposed. Pt catalysts show better performance for thermocatalytic decomposition of phosgene. This review will provide some references for the design and synthesis of high-performance materials for thermocatalytic decomposition of chemical warfare agents.
The effects on chromium (Cr) and selenium (Se) in blood of rats to different serine intakes was studied. After adapting for 5 days, pregnant rats sere randomly divided into 4 groups:control group, A, B and C group. Basic feed was given in control group and A group, meanwhile serine and glycine deficiency feed was given in B and C group. PHGDH inhibitor was intraperitoneal injected into A and C group. The chromium and selenium contents in pregnant rats were determined by inductively coupled plasma mass spectrometry (ICP-MS). Offspring rats from control group pregant rats were collected as control group. Offspring rats of C group were divided into 4 groups:SD group, SD+L group, SD+M group and SD+H group. Control group rats were feeded with basic food. SD group, SD+L group, SD+M group and SD+H group were given serine and glycine deficiency feed. After 1 months, 0.76 mg/100 g bw,1.52 mg/100 g bw and 3.04 mg/100 g bw serine were given to SD+L group, SD+M group and SD+H group, repectively. The chromium and selenium contents in offspring rats were determined by ICP-MS. There is no significant difference for the Cr contents betweent different groups. As the level of serine and glycine intakes decreased, the levels of Se in blood were increased. A positive relationship between blood Se and Cr content was found in pregnant rats, and not observed in offspring rats. For offsping rats, as the serine intakes increased, the Se and Cr content were increased. Conclusion the blood Cr and Se level were effected by the serine intakes.
Shimadzu's GPC-GC-MS/MS system was used to establish a screening method for screening non-target pesticide residues in food without standard products. After simple pre-treatment, the food samples were added with 10 kinds of pesticide residues, and the sensitivity of the target components was investigated by the established MRM collection method. At 10 μg·L-1 concentration level, 10 common pesticide residues in food samples were screened and the corresponding signals were high. The method is simple and easy to operate, has high sensitivity, and fully meets the requirements for screening and testing pesticide residues in food safety.
In order to understand pollution characteristics and ecological risk of polycyclic aromatic hydrocarbons (PAHs) in surface sediment from Sanya River, the concentration and composition of 16 priority PAHs were detected by accelerated solvent extraction (ASE) and high performance liquid chromatography (HPLC). The results showed that the total PAHs level (dry weight) reached 3.23-493 ng·g-1 and the average amount was 211 ng·g-1. Compared with other areas, the survey area was at low PAHs pollution level. The PAHs in the surface sediments of the survey area were primarily 3-5 rings. Source analysis showed that PAHs were mainly originated from combustion of firewood and coal. According to the assessment results of the Sediment Quality Guidelines (SQGs) and the Sediment Quality Standards (SQSs), the assessment results indicated that the PAHs in the surface sediments of the Sanya River are at a lower ecological risk level, but will pose a slight potential threat to the benthic organisms living in the region for a long time. Corresponding control measures should be taken to control the discharge of the PAHs into the Sanya River.