Pollution characteristics of 15 gas- and particle-phase phthalates in indoor and outdoor air in Hangzhou

Phthalate esters (PAEs), typical pollutants widely used as plasticizers, are ubiquitous in various indoor and outdoor environments. PAEs exist in both gas and particle phases, posing risks to human health. In the present study, we chose four typical kinds of indoor and outdoor environments with the longest average human residence times to assess the human exposure in Hangzhou, including newly decorated residences, ordinary residences, offices and outdoor air. In order to analyze the pollution levels and characteristics of 15 gas- and particle-phase PAEs in indoor and outdoor environments, air and particulate samples were collected simultaneously. The total PAEs concentrations in the four types of environments were 25,396, 25,466.8, 15,388.8 and 3616.2?ng/m³, respectively. DEHP and DEP were the most abundant, and DMPP was at the lowest level. Distinct variations in the distributions of indoor/outdoor, gas/particle-phase and different molecular weights of PAEs were observed, showing that indoor environments were the main sources of PAEs pollution. While most PAEs tended to exsit in indoor sites and gas-phase, the high-molecular-weight chemicals tended to exist in the particle-phase and were mainly found in PM_2.5. PAEs were more likely adsorbed by small particles, especially for the indoor environments. There existed a good correlation between the particle matter concentrations and the PAEs levels. In addition, neither temperature nor humidity had obvious effects on the distributions of the PAEs concentrations.     

CO2 adsorption using TiO2 composite polymeric membranes: A kinetic study

CO₂ is the main greenhouse gas which causes global climatic changes on larger scale. Many techniques have been utilised to capture CO₂. Membrane gas separation is a fast growing CO₂ capture technique, particularly gas separation by composite membranes. The separation of CO₂ by a membrane is not just a process to physically sieve out of CO₂ through the controlled membrane pore size. It mainly depends upon diffusion and solubility of gases, particularly for composite dense membranes. The blended components in composite membranes have a high capability to adsorb CO₂. The adsorption kinetics of the gases may directly affect diffusion and solubility. In this study, we have investigated the adsorption behaviour of CO₂ in pure and composite membranes to explore the complete understanding of diffusion and solubility of CO₂ through membranes. Pure cellulose acetate (CA) and cellulose acetate-titania nanoparticle (CA-TiO₂) composite membranes were fabricated and characterised using SEM and FTIR analysis. The results indicated that the blended CA-TiO₂ membrane adsorbed more quantity of CO₂ gas as compared to pure CA membrane. The high CO₂ adsorption capacity may enhance the diffusion and solubility of CO₂ in the CA-TiO₂ composite membrane, which results in a better CO₂ separation. The experimental data was modelled by Pseudo first-order, pseudo second order and intra particle diffusion models. According to correlation factor R², the Pseudo second order model was fitted well with experimental data. The intra particle diffusion model revealed that adsorption in dense membranes was not solely consisting of intra particle diffusion.     

静态顶空气相色谱法对土壤中乙醛等物质分析及研究

研究用静态顶空技术处理土壤,从而建立了静态顶空-气相色谱(GC-FID)测定土壤中的乙醛、丙烯醛、丙烯腈和吡啶的检测分析方法。在一定的静态顶空和气相色谱条件下,进行了顶空的时间和温度优化,确定了静态顶空气相色谱法测定土壤中乙醛、丙烯醛、丙烯腈和吡啶方法的检出限,并取得了满意的分离效果、线性回归方程、精密度和准确度。结果表明:用顶空气相色谱法处理土壤样品,可以减少土壤中待测有机物的损失,提高实验分析的灵敏度和准确度。     

Cattle manure biochar and earthworm interactively affected CO2 and N2O emissions in agricultural and forest soils: Observation of a distinct difference

• Earthworms increase CO₂ and N₂O emissions in agricultural and forest soil. • 10% biochar suppresses CO₂ and N₂O emissions in forest soil. • Biochar interacted with earthworm to significant affect CO₂ and N₂O emissions. The application of manure-derived biochar offers an alternative to avoid the direct application of manure to soil causing greenhouse gas emission. Soil fauna, especially earthworms, can markedly stimulate carbon dioxide (CO₂) and nitrous oxide (N₂O) emissions from soil. This study therefore investigated the effect of cattle manure biochar (added at rates of 0, 2%, or 10%, coded as BC0, BC2 and BC10, respectively) application, with or without earthworm Aporrectodea turgida, on emissions of CO₂ and N₂O and changes of physic-chemical properties of agricultural and forest soils in a laboratory incubation experiment. The BC10 treatment significantly enhanced cumulative CO₂ emissions by 27.9% relative to the untreated control in the agricultural soil. On the contrary, the BC2 and BC10 treatments significantly reduced cumulative CO₂ emissions by 16.3%–61.1% and N₂O emissions by 92.9%–95.1% compared to the untreated control in the forest soil. The addition of earthworm alone significantly enhanced the cumulative CO₂ and N₂O fluxes in agricultural and forest soils. Cumulative CO₂ and N₂O fluxes were significantly increased when BC2 and BC10 were applied with earthworm in the agricultural soil, but were significantly reduced when BC10 was applied with earthworm in the forest soil. Our study demonstrated that biochar application interacted with earthworm to affect CO₂ and N₂O emissions, which were also dependent on the soil type involved. Our study suggests that manure biochar application rate and use of earthworm need to be carefully studied for specific soil types to maximize the climate change mitigation potential of such management practices.     

顶空气相色谱/质谱法测定水中四乙基铅的关键因素研究

采用顶空气相色谱/质谱法联用技术测定水中的四乙基铅,对涉及的关键操作环节及重点技术问题进行了研究。结果表明,在避光条件下于4℃低温冷藏并密封保存,添加甲醇作为保护剂,保存时间不应超过3 d。实验选择进样口温度为220℃,顶空瓶压力为96.52 kPa,调节载气流量设置实际分流比为51,可以有效改善顶空进样测定样品时存在的不出峰、不稳定或灵敏度降低的问题。对地表水、自来水及生活污水实际样品进行四乙基铅测定和加标回收分析,加标回收率为81.0%~110%,相对标准偏差(RSD)为2.5%~7.4%,能够满足《水质四乙基铅的测定顶空/气相色谱质谱法》(HJ 959—2018)的测定要求。将顶空进样法与吹扫捕集法进行比较,结果表明顶空进样法稳定性更好,适合大批量四乙基铅样品的连续测定。     

顶空-毛细管气相色谱法同步测定水中吡啶丙酮乙腈

建立了顶空-毛细管气相色谱测定水中吡啶丙酮乙腈的方法,不用有机溶剂萃取和浓缩,减少了损失和对环境的污染,具有灵敏度高、检出限低、定量准确、操作简便等特点。当取样量为5ml时,检出限可达到0.006~0.03mg/L级,相对标准偏差为1.0%~2.3%,加标回收率在78.0%~100.2%之间,完全适合水中吡啶丙酮乙腈的测定。     

土壤中有机污染物的气相色谱-四极杆飞行时间质谱非靶标筛查

本文基于气相色谱-四极杆飞行时间质谱(GC-QTOF/MS)对宜昌某化学工业园区内的土壤进行潜在有机污染物的非靶标筛查.根据已有高分辨数据库和保留时间信息,采用精确质量数提取筛查流程识别出样品中96种污染物,主要以多环芳烃及其代谢产物、氯苯类和农药为主.进一步通过未知物分析软件解卷积功能和质谱NIST数据库的匹配,发现了如二氯苯胺、9-芴酮、3-甲基二苯并噻吩等更多的污染物.该方法能够快速筛查和识别出样品中潜在有机污染物,为当地污染物的风险管控提供借鉴意义.     

The TNO multi-energy method combined to mathematical programming and computational fluid dynamics for optimisation of gas detectors

Gas leakage is a matter of concern for several industries such as oil and gas, mining, food, and healthcare. When the industry considers gas detectors, the main questions are: How many gas detectors are required? Where is the best location to install them? To answer these questions Computational Fluid Dynamics (CFD) simulations and optimisation procedures are employed to calculate the plume location and plume volume to better position the gas detectors. We investigated how the optimisation cell size for the set covering problem can be calculated based on a given explosion overpressure threshold. Resorted by the multi-energy explosion model, we calculate the flammable cloud volume associated with a pre-defined overpressure value. The cloud volume is applied in the solution of the set covering problem and an optimal set for the gas detectors is obtained. The final gas detector network (number and location of the devices) is validated against CFD simulations for small releases. The results provide evidence that the optimal gas detector networks is able to detect gas leaks within a feasible time.     

Experimental and computational fluid dynamic (CFD) simulation of leak shapes and sizes for gas pipeline

In this paper, a parametric study has been carried out to predict the exit velocity of air through the leakage in the pipe with the help of CFD software ANSYS Fluent. The effect of air pressure in the pipe and the shape of leakage have been studied. Further experiments were also carried out to determine the exit velocity for the defined shape of leakage by varying the air pressure in the pipe. Experimentally, the velocity at a distance of 8 cm from the location of a leak in the horizontal plane was obtained with the help of differential pressure transducers. Using the experimental results, the computational results were validated. The results of the parametric simulation study showed that even for a pressure of 2 bars the velocity profile at the leak location indicates the supersonic state where the Mach number is greater than 1. The study is useful because it may be used as a foundation for risk assessment and safety management in the case of flammable gas leaks through gas pipes.