Chemical characterization of volatile organic compounds (VOCs) emitted from multiple cooking cuisines and purification efficiency assessments.

Cooking process can produce abundant volatile organic compounds (VOCs), which are harmful to environment and human health. Therefore, we conducted a comprehensive analysis in which VOCs emissions from multiple cuisines have been sampled based on the simulation and acquisition platform, involving concentration characteristics, ozone formation potential (OFP) and purification efficiency assessments. VOCs emissions varied from 1828.5 to 14,355.1 µg/m3, with the maximum and minimum values from Barbecue and Family cuisine, respectively. Alkanes and alcohol had higher contributions to VOCs from Sichuan and Hunan cuisine (64.1%), Family cuisine (66.3%), Shandong cuisine (69.1%) and Cantonese cuisine (69.8%), with the dominant VOCs species of ethanol, isobutane and n-butane. In comparison, alcohols (79.5%) were abundant for Huaiyang cuisine, while alkanes (19.7%), alkenes (35.9%) and haloalkanes (22.9%) accounted for higher proportions from Barbecue. Specially, carbon tetrachloride, n-hexylene and 1-butene were the most abundant VOCs species for Barbecue, ranging from 8.8% to 14.6%. The highest OFP occurred in Barbecue. The sensitive species of OFP for Huaiyang cuisine were alcohols, while other cuisines were alkenes. Purification efficiency assessments shed light on the removal differences of individual and synergistic control technologies. VOCs emissions exhibited a strong dependence on the photocatalytic oxidation, with the removal efficiencies of 29.0%-54.4%. However, the high voltage electrostatic, wet purification and mechanical separation techniques played a mediocre or even counterproductive role in the VOCs reduction, meanwhile collaborative control technologies could not significantly improve the removal efficiency. Our results identified more effective control technologies, which were conductive to alleviating air pollution from cooking emissions.

Process-specific volatile organic compounds emission characteristics, environmental impact and health risk assessments of the petrochemical industry in the Beijing-Tianjin-Hebei region.

Volatile organic compounds (VOCs) concentration, source profiles, O3 and SOA formation, and health risks were investigated in the petrochemical industry in Beijing-Tianjin-Hebei. The results showed that total VOCs concentrations were 547.1-1956.5 µg·m-3, and alkanes were the most abundant group in all processes (31.4%-54.6%), followed by alkenes (20.6%-29.2%) and aromatics (10.1%-25.1%). Moreover, ethylene (11.3%), iso-pentane (7.1%), n-hexane (5.1%), benzene (4.9%) and 2,2-dimethylbutae (4.8%) were identified as the top five species released for the whole petrochemical industry. The coefficient of divergence between the source profiles from different processes was 0.49-0.73, indicating that most source profiles must not be similar. Moreover, because of the different raw materials and technologies used, the source profiles in this study are significantly different from those of other regions. The ozone and secondary organic aerosol formation potentials (OFPs and SOAPs) were evaluated, suggesting that ethylene, propylene, 1-butene, m,p-xylene, and 1,3-butadiene should be preferentially controlled to reduce OFPs. That benzene, toluene, ethylbenzene, m,p-xylene, isopropylbenzene, o-ethyltoluene, and 1,3,5-trimethylbenzene should be priority control compounds for SOAPs. Additionally, the total hazard ratio for non-cancer risk ranged from 0.9 to 7.7, and only living area was unlikely to be related to adverse health effects. Cancer risks associated with organic chemicals, rubber synthesis, oil refining, and wastewater collection and treatment have definite risks, whereas other processes have probable risks. This study provides a scientific basis for VOCs emission control and management and guides human health in the petrochemical industry.

ß-Cyclodextrin functionalized magnetic polyamine-amine dendrimers for high enrichment and effective analysis of trace bisphenolic pollutants in beverages.

Bisphenols (BPs) are typical endocrine disruptors, which can cause great effects on environmental, organisms and human health. In this study, ß-Cyclodextrin (ß-CD) functionalized polyamidoamine dendrimers-modified Fe3O4 nanomaterials (MNPs@PAMAM (G3.0)@ß-CD) were facilely synthesized. It exhibited good adsorption capacities for BPs, which was utilized to construct a sensitive tool in combination with high performance liquid chromatography for monitoring BPs such as bisphenol A (BPA), tetrabromobisphenol A (TBBPA), bisphenol S (BPS), bisphenol AF (BPAF) and bisphenol AP (BPAP) in beverage samples. The factors affecting the enrichment were examined such as generation of adsorbent, dosage of adsorbent, type and volume of eluting solvent, elution time and pH value of sample solution. The optimal parameters for enrichment was as follows: dosage of adsorbent, 60 mg; adsorption time, 50min; sample pH, pH7; elutent, 9 mL mixture of methanol and acetone(1:1); elution time, 6min; sample volume, 60 mL. The experimental results demonstrated that the adsorption conformed to pseudo-second-order kinetic model and Langmuir adsorption isotherm model. The results showed the maximum adsorption capacities of BPS, TBBPA, BPA, BPAF and BPAP were 131.80 µgg-1, 139.84 µgg-1, 157.08 µgg-1, 142.11 µgg-1 and 134.23 µgg-1, respectively. Under optimal conditions, BPS had good linear relationship over range from of 0.5-300 µgL-1, and the linear ranges of BPA, TBBPA, BPAF and BPAP ranged from 0.1 to 300 µgL-1. The limits of detection (S/N = 3) for BPs were good in range of 0.016-0.039 µgL-1. The spiked recoveries of target bisphenols (BPs) in beverages were approving over range from 92.3% to 99.2%. The established method possessed merits of easy to operate, good sensitivity, rapidness as well as environmental friendliness, and which earned great application potential for the enrichment and detection of trace BPs in practical samples.

Highly efficient and simultaneous magnetic solid phase extraction of heavy metal ions from water samples with l-Cysteine modified magnetic polyamidoamine dendrimers prior to high performance liquid chromatography.

Due to the strong metal-sulfur interaction between mercapto groups and metal ions, which can be used to functionalize polyamidoamine dendrimer decorated Fe3O4 nanoparticles for high enrichment of trace heavy metal ions from waters. Based on this concept, polyamidoamine dendrimer modified Fe3O4 nanomaterials were functionalized with l-Cysteine and a new magnetic solid phase extraction for rapid adsorption and separation of Hg2+, Pb2+, Co2+ and Cd2+ from waters was established. The factors affecting extraction efficiency have been optimized. Upon the optimal parameters, the established method provided good linear ranges of 0.1-200 µg L-1 for Hg2+ and 0.05-200 µg L-1 for Pb2+, Co2+ and Cd2+, and high sensitivity with limits of detection (LOD) of 0.018 µg L-1, 0.014 µg L-1, 0.013 µg L-1 and 0.025 µg L-1 for Cd2+, Pb2+, Co2+ and Hg2+, respectively. Real water samples were utilized to validate the proposed method, and achieved results revealed that the proposed method was sensitive, effective, stable and suitable for monitoring Pb2+, Cd2+, Co2+and Hg2+ in environmental waters. This work provided a novel strategy for the simultaneous analysis of target cations in waters, and a new direction for developing decoration method of nanomaterials according to specific purpose.

A comprehensive study of volatile organic compounds from the actual emission of Chinese cooking.

China's current perspective for big cities was filled with great population, great number of restaurants, growing gaseous pollutants, and great pollution. Volatile organic compounds (VOCs) were the main components of catering industry gaseous pollutants. In this study, we collected and analyzed VOCs from home cooking (HC), Sichuan and Hunan cuisine (S&H), Shandong cuisine (SD), Anhui cuisine (AH), Beijing cuisine (BJ), and barbecue (BBQ). The result showed that BBQ gave the highest VOC concentration (6287.61 µg m-3), followed by HC (1806.11 ± 2401.85 µg m-3), SD (2238.55 ± 2413.53 µg m-3), AH (1745.89 µg m-3), S&H (1373.58 ± 1457.45 µg m-3), and BJ (288.81 µg m-3). The abundance of alkane was higher among BBQ, Anhui cuisine, and HC with the proportion from 33 to 71%. SD contained higher halohydrocarbons proportion (33%). BJ was characterized by high-oxygenated volatile organic compounds proportion (50%). The ozone formation potential (OFP) of BBQ was much greater than other cuisines. The degree of stench pollution from cooking VOCs of HC was 17.51 ± 16.95, followed by S&H (15.77 ± 16.85), SD (15.12 ± 14.17), AH (16.29), BBQ (2.58), and BJ (1.81). Benzene had the highest life cancer risk (LCR) in SD (2.11×10-5 ± 3.12×10-5), following HC (4.50×10-6 ± 3.83×10-6) and S&H (4.08×10-6 ± 4.49×10-6). Acrolein had a high hazard index (HI) in HC (789.81 ± 768.77), following AH (728.78), S&H (689.89 ± 776.07), SD (664.29 ± 648.77), BBQ (65.93), and BJ (62.84).

Highly efficient adsorption and mechanism of alkylphenols on magnetic reduced graphene oxide.

The influence of alkylphenols to environment cannot be ignored, as they are common product from chemical industries and potential threat to human health. Some alkylphenols are listed as persistent toxic substances (PTS) by the United Nations Environment Programme (UNEP). In this study, the optimized magnetic reduced graphene oxide (MrGO) was synthesized by a facile solvothermal method, and investigated for adsorption of three typical alkylphenols. In neutral condition, MrGO showed extremely high adsorption capacity of three typical alkylphenols, 4-heptylphenol (4-HP), 4-tert-octylphenol (4-OP), and 4-nonylphenol (4-NP), which could reach 938.9 mg g-1 (40 °C), 987.8 mg g-1 (40 °C), and 989.7 mg g-1 (20 °C), respectively. This study revealed that the adsorption process was a heterogeneous multi-layer physical adsorption, and the adsorption rates were related to the number of unoccupied vacancies on the adsorbent surface. From batch experiments and density functional theory (DFT) calculations, the main adsorption interactions between MrGO and alkylphenols were deduced to be π-π, hydrogen-bond, and hydrophobic interactions. What's more, the different affinities of MrGO towards different targets were further distinguished and explained in detail. The wonderful stability and recyclability of MrGO made it a promising cost-effective remediation candidate.

Preparation of Polyamidoamine Dendrimer Modified Magnetic Nanoparticles and Its Application for Reliable Measurement of Sudan Red Contaminants in Natural Waters at Parts-Per-Billion Levels.

The health threat from Sudan red dyes has been the subject of much attention in recent years and is crucial to design and establish reliable measurement technologies. In the present study, a new magnetic nanomaterial, polyamidoamine dendrimer-modified magnetic nanoparticles (Gn-MNPs), was synthesized and characterized. The nanomaterials had good adsorption capacity for Sudan dyes from natural waters. G1.5-MNPs possessed excellent adsorption capacity and a linear adsorption relationship over the range from 0.02 to 300 µg L-1 of Sudan dyes with relative coefficients all larger than 0.996. The sensitivity of the proposed method was excellent with detection limits over the range from 1.8 to 5.5 ng L-1 and the precision was less than 3.0%. G1.5-MNPs showed a remarkable application potential for the enrichment of trace environment pollutants in aqueous samples and the developed method based on this nanomaterial could be a robust and reliable alternative tool for routine monitoring of such pollutants.

[Emission Characteristics of the Catering Industry in Beijing].

The emissions of the catering industry are important sources of air pollution in megacities in China. A total of 41 restaurants in Beijing were selected as the sampling sites to evaluate the contribution of the catering industry to megacity air pollution. The original emissions load of cooking fume, particulate matter, and non-methane hydrocarbon (NMHC) were studied via field tests for different types of restaurants. The results showed that the cooking fume, particulate matter, and NMHCs generated from the kitchen were 1.93, 6.6, and 10.9 mg·m-3, respectively. An evaluation method based on working days was developed. Considering the total number of restaurants in Beijing, the original emission loads of 2019 were calculated. The cooking fume, particulate matter, and NMHC emissions were 5512, 18849, and 6169 t, respectively. The Pearson numbers of the cooking fume emission and particular matter emission from Sichuan and Hunan cuisine, Roast Duck, Grill and Barbecue, and Chinese Home-Style cuisine were all above 0.6, which indicated a high level of correlation between the cooking fume emission and particular matter emission. Notably, the Pearson numbers of Sichuan and Hunan cuisine and Roast Duck were both higher than 0.8, which indicates a strong correlation between the cooking fume emission and particular matter emission.

Trace determination of organophosphorus pesticides in environmental samples by temperature-controlled ionic liquid dispersive liquid-phase microextraction.

This paper described a new approach for the determination of organophosphorus pesticides by temperature-controlled ionic liquid dispersive liquid-phase microextraction prior to high-performance liquid chromatography with ultraviolet detection. Methylparathion and phoxim, two of the typical organophosphorus pesticides, were used as the model analytes for the investigation of the development and application of the new microextraction method. 1-Hexyl-3-methylimidazolium hexafluorophosphate [C6MIM][PF6] was used as the extraction solvent and the factors affecting the extraction efficiency such as the volume of [C6MIM][PF6], pH of working solutions, extraction time, centrifuging time, dissoluble temperature and salt effect were optimized. Under the optimal extraction conditions, methylparathion and phoxim exhibited good linear relationship in the concentration range of 1-100 ng mL(-1). The detection limits were 0.17 ng mL(-1) and 0.29 ng mL(-1), respectively. Precisions of proposed method (RSDs, n=6) were 2.5% and 2.7%, respectively. This proposed method was successfully applied in the analysis of four real environmental water samples and good spiked recoveries over the range of 88.2-103.6% were obtained. These results indicated that temperature-controlled ionic liquid dispersive liquid-phase microextraction had excellent application prospect in environmental field.

Temperature-controlled ionic liquid dispersive liquid phase micro-extraction.

The present study reports a novel, green and environmental benign sample enrichment method termed temperature-controlled ionic liquid dispersive liquid phase micro-extraction. An ionic liquid [C6MIM][PF6], was used as the extraction solvent and pyrethroid pesticides as the model compounds. The ionic liquid was dispersed completely into the aqueous solution under the drive of temperature, and the analytes will more easily migrate into the ionic liquid phase because of the much larger contact area than that of conventional single drop liquid micro-extraction. Results obtained indicated that this system could be tuned to a great extent because ionic liquids can be designable and the method does not suffer from the limitations of that in conventional solvent micro-extraction. Analytical parameters of the proposed method were investigated and good linear range (1.5-100 microg L(-1)), detection limits (0.28-0.6 microg L(-1)), and precision (RSD of 2.7-9.3%, n=6) was obtained. Good spiked recoveries from six real water samples proved that this method was competitive in practical applications. Considering the large variety of ionic liquids and the tunable amounts of used ionic liquids in different experiments, the proposed method earns many merits and will have a wide application perspective in the future.

Application of multiwalled carbon nanotubes treated by potassium permanganate for determination of trace cadmium prior to flame atomic absorption spectrometry.

In this study we investigated the enrichment ability of oxidized multiwalled carbon nanotubes (MWCNTs) and established a new method for the determination of trace cadmium in environment with flame atomic absorption spectrometry. The MWCNTs were oxidized by potassium permanganate under appropriate conditions before use as preconcentration packing. Parameters influencing the recoveries of target analytes were optimized. Under optimal conditions, the target analyte exhibited a good linearity (R2=0.9992) over the concentration range 0.5-50 ng/ml. The detection limit and precision of the proposed method were 0.15 ng/ml and 2.06%, respectively. The proposed method was applied to the determination of cadmium in real-world environmental samples and the recoveries were in the range of 91.3%-108.0%. All these experimental results indicated that this new procedure could be applied to the determination of trace cadmium in environmental waters.

Rapid determination of phenolic compounds in water samples by alternating-current oscillopolarographic titration.

A rapid, simple and sensitive method was demonstrated for the determination of phenolic compounds in water samples by alternating-current oscillopolarographic titration. With the presence of sulfuric acid, phenol could be transferred into a nitroso-compound by reacting with NaNO2. The titration end-point was obtained by the formation of a sharp cut in the oscillopolarographic with infinitesimal NaNO2 on double platinum electrodes. The results showed that phenol concentration had an excellent linear relationship over the range of 4.82 x 10(-6)-9.65 x 10(-3) mol/L, the RSD of the proposed method was lower than 1.5%, and the spiked recoveries of three real water samples were in the range of 95.6%-106.9%.

Nitrogen addition and warming independently influence the belowground micro-food web in a temperate steppe.

Climate warming and atmospheric nitrogen (N) deposition are known to influence ecosystem structure and functioning. However, our understanding of the interactive effect of these global changes on ecosystem functioning is relatively limited, especially when it concerns the responses of soils and soil organisms. We conducted a field experiment to study the interactive effects of warming and N addition on soil food web. The experiment was established in 2006 in a temperate steppe in northern China. After three to four years (2009-2010), we found that N addition positively affected microbial biomass and negatively influenced trophic group and ecological indices of soil nematodes. However, the warming effects were less obvious, only fungal PLFA showed a decreasing trend under warming. Interestingly, the influence of N addition did not depend on warming. Structural equation modeling analysis suggested that the direct pathway between N addition and soil food web components were more important than the indirect connections through alterations in soil abiotic characters or plant growth. Nitrogen enrichment also affected the soil nematode community indirectly through changes in soil pH and PLFA. We conclude that experimental warming influenced soil food web components of the temperate steppe less than N addition, and there was little influence of warming on N addition effects under these experimental conditions.

Preconcentration sensitive determination of pyrethroid insecticides in environmental water samples with solid phase extraction with SiO2 microspheres cartridge prior to high performance liquid chromatography.

Present study developed a new method for the sensitive determination of pyrethroid insecticides with solid phase extraction in combination with high performance liquid chromatography and UV detector. SiO(2) microspheres, a new SiO(2) based material, was investigated for the enrichment ability and applicability as the solid phase extraction sorbent. Four pyrethroid pesticides such as fenpropathrin, cyhalothrin, fenvalevate and biphenthrin were used as the target analytes. Parameters that maybe influence the extraction efficiency such as the eluent type and its volume, sample flow rate, sample pH, and the sample volume were optimized in detail, and the optimal conditions were as followed: sample volume, 100mL; concentration of methanol, 30%; acetone volume, 5mL; sample flow rate, 4.2mLmin(-1); sample pH, 7. The experimental results indicated that there was good linearity in the concentration range of 0.1-50microgL(-1) except biphenthrin in the range of 0.05-25microgL(-1). The detection limits for fenpropathrin, cyhalothrin, fenvalevate and biphenthrin were in the range of 0.02-0.08microgL(-1). The intra-day and day to day precisions (RSDs, n=6) were in the ranges of 2.6-4.4% and 5.3-7.2%, respectively. The method was validated with five real environmental water samples, and all these results proved that proposed method could be used as a good alternative for the routine analysis for such pollutants in environmental samples.

Temperature-controlled ionic liquid-liquid-phase microextraction for the pre-concentration of lead from environmental samples prior to flame atomic absorption spectrometry.

Hydrophobic ionic liquid could be dispersed into infinite droplets under driving of high temperature, and then they can aggregate as big droplets at low temperature. Based on this phenomenon a new liquid-phase microextraction for the pre-concentration of lead was developed. In this experiment, lead was transferred into its complex using dithizone as chelating agent, and then entered into the infinite ionic liquid drops at high temperature. After cooled with ice-water bath and centrifuged, lead complex was enriched in the ionic liquid droplets. Important parameters affected the extraction efficiency had been investigated including the pH of working solution, amount of chelating agent, volume of ionic liquid, extraction time, centrifugation time, and temperature, etc. The results showed that the usually coexisting ions containing in water samples had no obvious negative effect on the recovery of lead. The experimental results indicated that the proposed method had a good linearity (R=0.9951) from 10 ng mL(-1) to 200 ng mL(-1). The precision was 4.4% (RSD, n=6) and the detection limit was 9.5 ng mL(-1). This novel method was validated by determination of lead in four real environmental samples for the applicability and the results showed that the proposed method was excellent for the future use and the recoveries were in the range of 94.8-104.1%.

Enrichment and sensitive determination of dichlorodiphenyltrichloroethane and its metabolites with temperature controlled ionic liquid dispersive liquid phase microextraction prior to high performance liquid phase chromatography.

Dichlorodiphenyltrichloroethane (DDT) and its main metabolites are important environmental pollutants and have been in the focusing center. It is of great value to develop simple, rapid, sensitive and easy to operate method for monitoring them. Present work established a novel temperature controlled ionic liquid dispersive liquid phase microextraction method in combination with high performance liquid chromatography for the enrichment and determination of DDT and its metabolites. Proposed method used only ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate ([C(6)MIM][PF(6)]) for the enrichment and overcame the demerits of conventional single drop liquid phase microextraction and dispersive liquid-liquid microextraction. Temperature has two functions here, one is to promote the dispersing of ionic liquid into the solution and forming infinitesimal micro-drop and increasing the chance of the analytes extracted into ionic liquid phase, and the other one is to perform phase-separation. A series of factors that would affect the extraction performance was systematically investigated and optimized. The experimental results indicated that the detection limits obtained for p,p'-DDD, p,p'-DDT, o,p'-DDT and p,p'-DDE were 0.24, 0.24, 0.45, 0.24 ng mL(-1), respectively. The linear ranges for them were from 1.0 to 100 ng mL(-1), and the precisions were between 3.8% and 6.7% (n=6). The proposed method was validated with four real-world samples and excellent results were achieved.

Determination of atrazine and simazine in environmental water samples by dispersive liquid-liquid microextraction with high performance liquid chromatography.

This paper describes a new method for the rapid and sensitive analysis of atrazine and simazine based on the dispersive liquid-liquid microextraction with carbon tetrachloride and methanol as the extraction solvent and disperser solvent. Under the optimal conditions, there are excellent linear relationships between the peak area and the concentration in the range of 0.5 - 50 microg L(-1) for atrazine and 0.1 - 50 microg L(-1) for simazine. The limits of detection were 0.1 and 0.04 microg L(-1) for atrazine and simazine, respectively. The proposed method was also applied to the analysis of real water samples, and excellent results were achieved with spiked recoveries in the range of 60.7 - 91.4%. All these results demonstrate that the proposed method would be widely used in many fields in the future.