Coking and decoking chemistry for resource utilization of polycyclic aromatic hydrocarbons(PAHs)and low-carbon process

Low-carbon process for resource utilization of polycyclic aromatic hydrocarbons(PAHs)in zeolitecatalyzed processes,geared to carbon neutrality-a prominent trend throughout human activities,has been bottlenecked by the lack of a complete mechanistic understanding of coking and decoking chemistry,involving the speciation and molecular evolution of PAHs,the plethora of which causes catalyst deactivation and forces regeneration,rendering significant CO_(2) emission.Herein,by exploiting the high-resolution matrix-assisted laser desorption/ionization Fourier-transform ion cyclotron resonance mass spectrometry(MALDI FT-ICR MS),we unveil the missing fingerprints of the mechanistic pathways for both formation and decomposition of cross-linked cage-passing PAHs for SAPO-34-catalyzed,industrially relevant methanol-to-olefins(MTO)as a model reaction.Notable is the molecule-resolved symmetrical signature:their speciation originates exclusively from the direct coupling of in-cage hydrocarbon pool(HCP)species,whereas water-promoted decomposition of cage-passing PAHs initiates with selective cracking of inter-cage local structures at 8-rings followed by deep aromatic steam reforming.Molecular deciphering the reversibly dynamic evolution trajectory(fate)of full-spectrum aromatic hydrocarbons and fulfilling the real-time quantitative carbon resource footprints advance the fundamental knowledge of deactivation and regeneration phenomena(decay and recovery motifs of autocatalysis)and disclose the underlying mechanisms of especially the chemistry of coking and decoking in zeolite catalysis.The positive yet divergent roles of water in these two processes are disentangled.These unprecedented insights ultimately lead us to a steam regeneration strategy with valuable CO and H_(2) as main products,negligible CO_(2) emission in steam reforming and full catalyst activity recovery,which further proves feasible in other important chemical processes,promising to be a sustainable and potent approach that contributes to carbon-neutral chemical industry.

Transport and behavior of marine oil spill containing polycyclic aromatic hydrocarbons in mesocosm experiments

Polycyclic aromatic hydrocarbons(PAHs)are one of the most important groups in oil,and re sponsible for major toxic and/or carcinogenic impact on humans and wildlife.It is important to understand the behavior of PAHs in marine environment after an oil-spill incident.However,interaction between petroleum PAHs and microbial communities in a marine environment remains unclear.Therefore,a series of mesocosm experiments were conducted.in which water-accommodated fraction(WAF)of oil was generated to simulate an oil-spill scenario and to analyze the transport and behavior of marine oil spill containing PAHs with and without dispersants.Results indicate that the application of dispersant could increase the concentration of total PAHs in water column due mainly to significant increase in the concentration of highmolecular weight(HMW)PAHs at a lower removal rate.At the end of the 7-day experiment,significant amount of HMW PAHs were accumulated in sediment.In general,the application of dispersant did not increase the sediment uptake of PAHs but increased the PAHs concentration in water column.

Development of analytical methods for polycyclic aromatic hydrocarbons (PAHs) in airborne particulates: A review

In the present work, the different sample collection, pretreatment and analytical methods for polycyclic aromatic hydrocarbons （PAHs） in airborne particulates is systematacially reviewed, and the applications of these pretreatment and analytical methods for PAHs are compared in detail. Some comments on the future expectation are also presented.

Ultrasensitive Detection of Polycyclic Aromatic Hydrocarbons(PAHs) in Water Using Three-Dimensional SERS Substrate Based on Porous Material and pH 13 Gold Nanoparticles

Sensitivity is crucially important for surface-enhanced Raman spectroscopy(SERS)application to detect trace-level polycyclic aromatic hydrocarbons(PAHs)in the seawater.In this study,a high sensitivity three-dimensional(3-D)SERS substrate composed with syringe filter,glycidyl methacrylate-ethylene dimethacrylate(GMA-EDMA)porous material and optimal parameters(57 nm,pH 13)gold nanoparticles(Au NPs)was developed for the detection of PAHs in water.The enhancement effect and repeatability of this 3-D substrate were also explored.The Raman intensity of pyrene using 3-D SERS substrate is about 8 times higher than that of substrate only using p H 13 gold colloid solution and about 12 times higher than that of substrate using natural Au NPs and GMA-EDMA porous material,which means both the pH 13 AuN Ps and the GMA-EDMA porous material are important factors for the sensitivity of this 3-D SERS substrate.Good repeatability of this optimal 3-D substrate was obtained.The relative standard deviation(RSD)is less than 8.66% on the same substrate and less than 3.69% on other different substrates.Four kinds of PAHs,i.e.,phenanthrene,pyrene,benzo(a)pyrene,benzo(k)fluoranthene and their mixture,were detected at the different concentrations.Their limits of detection(LODs)are 8.3×10^-10(phenanthrene),2.1×10^-10(pyrene),3.8×10^-10(benzo(a)pyrene)and 1.7×10^-10 mol L^-1(benzo(k)fluoranthene),respectively.In addition,these four PAHs were also detected by fluorescence spectroscopy to evaluate the sensitivity of SERS technology using this optimal 3-D SERS substrate.The results showed that the sensitivity of SERS based on the 3-D SERS substrate even using the portable Raman system was closed to that of fluorescence spectroscopy.Therefore,the SERS technology using this optimal 3-D substrate is expected to be an in-situ method for the detection of environmental PAHs.

The Pollution Characteristic of Polycyclic Aromatic Hydrocarbons (PAHs) in Typical Sewage Irrigation Area in North of China

This research aims to investigate the pollution characteristic of PAHs in Xiaodian sewage irrigation area. The result shows that the concentrations ofPAHs range from 47.94 to 46432.85ng/g while that of the total components of the 16 kinds of PAHs are 5969.81ng/g. PAHs with for rings and more than 4 rings are the main and important pollutants in topsoils of Xiaodian District. The main input of PAHs is combustion source, and the main pollution source in this area is fired coal. The topsoils in Xiaodian District are polluted by human activity in varying degrees. 23 of all 31 topsoil samples have been heavily polluted, especially those located nearby developed industrial townships and irrigation channels.

The Study of Pollution of PAHs （Polycyclic Aromatic Hydrocarbons） in AI-Hilla River, Iraq by Using Bioindicator Freshwater Crab （Sesarma boulengeri Caiman）

The present study was used freshwater Crab （Sesarma boulengeri Caiman） as bioindicator to measured the PAHs levels in AI-Hilla River, Iraq, during the period from March 2010 to February 2011. Crab samples were collected from two sites on the AI-Hilla River. Sixteen of PAils compounds were identified seasonally in these samples. High mean value was （72.06 μg/g）, recorded by Dibenzo （a, h） anthracene （DbA） in Site 1 and low mean value was （0.36 μg/g） recorded by Anthracene （Ant） in Site 2. The study showed a clear variation in PAHs concentration independent from the seasons and locations. Site 1 recorded high value of HMW （high molecular weight） and LMW （low molecular weight） more than Site 2. The present study revealed that all PAHs compounds were from Pyrogenic Origin. Seven carcinogenic PAHs （cPAHs） were recorded in crab tissues that were collected from the AI-Hilla River. The TEF （toxicity equivalency factor） was calculated to toxicity equivalent crab concentration. From the results, the fresh water Crab Sesarma boulengeri is a good bioindicator to water pollution by PAHs.

CARBONIZED FIBROUS RESIN AS A NEW SORBENT FOR SAMPLING POLYCYCLIC AROMATIC HYDROCARBONS (PAHS) IN AMBIENT AIR

A new sampling method of ambient air analysis using carbonized fibrous resin as a sorbent for polycyclic aromatic hydrocarbons (PAHs) was reported. The physical and chemical properties of the carbonized fibrous resins were measured. The sample pretreatment with ultrasonic extraction and subsequent clean-up elution through a silica gel column was optimized. The suitable ultrasonic extraction conditions were selected as follows: resin weight was 1.5 g, ultrasonic extraction time 20 min, volume of extraction solvent 100 ml and extraction operation times 2~3. The concentrated extractable organic matter was submitted to next step of clean-up procedure of adsorption chromatography on silica gel column/n-hexane and a mixture of dichloromethene:n-hexane solution 2:3 (v/v). The PAHs fractions in the real samples from Changzhou, China were particularly analyzed using GC-MS data system and the data of mass spectra, retention times and scan numbers of the real samples were compared with that of the standards of 16 PAHs listed by the US EPA as 損riority pollutants?of the environment. The analysis of the real samples indicates that the carbonized fibrous resin is a good sorbent. The pretreatment of samples of ambient air with carbonized fibrous resin as a sorbent for PAHs is proved to be reliable and might be used for the procedure of the determination of PAHs in atmospheric environment.

Distribution and Risk Assessment of Polycyclic Aromatic Hydrocarbons in Mussels from the Middle and Lower Main Stream of Huaihe River

[ Object] The aim was to discuss the pollution status of polycyclic aromatic hydrocarbons （PAHs） in mussels from the middle and lower main stream of Huaihe River, which will provide a scientific basis for dietary safety of mussels. [ Method] Suspended matter, sediment, and mussel samples were collected from Wuxiaojie and Fushanji in middle and lower reaches of Huaihe River. All samples were extracted with Soxhlet, separated through Silica GeI-Al2O3 column, and determined by GC-MS, and then 16 typical PAHs contents in the prior table listed by American EPA were obtained. [ Result] The results indicated that total PAHs concentrations in suspended matters and sediments of Wuxiaojie were significantly higher than those in Fushanji respectively. However, PAHs concentrations in mussels of the two samplings showed little difference; as for single PAH component, low-ring PAHs were more advantaged in suspended matters of two sampling sites, while high-ring PAHs were more advantaged in mussels. PAHs in sediments of Wuxiaojie assumed low-ring aspect, though PAHs in sediments of Fushanji assumed high-ring aspect. [ Conclusion] In spite of that sediments and mussels were not yet contaminated according to the ecological risk assessment of PAHs, its potential hazards couldn＇t be ignored any more.

含过氧键化合物在土壤及地下水PAHs污染修复中的应用进展

土壤及地下水中多环芳烃(PAHs)污染的修复治理是当前亟需解决的问题,其中基于含过氧键化合物的高级氧化技术由于对土壤及地下水中PAHs具有高效的降解能力,在近年来受到越来越多的关注。本文重点总结了过氧化氢、过硫酸盐以及过氧乙酸在土壤及地下水中PAHs污染修复方面的研究,从过氧键断裂产生自由基的角度讨论了其活化机制与降解机理,探究了过氧乙酸在土壤及地下水中PAHs污染修复中的应用前景,分析了影响修复效率的主要外部因素。总体来看,不同活化方式所产生的自由基种类有所不同,对PAHs污染的修复效果也有所差异,与此同时,土壤及地下水复杂环境因素对修复效果有着重要的影响。因此在未来的研究中应开发新型活化材料,提高修复效果并降低二次污染,同时需针对不同的土壤及地下水环境选择合适的活化方式,采用表面活性剂增强氧化剂的修复范围,在过氧乙酸修复PAHs污染方面开展更深入的研究。含过氧键化合物修复PAHs污染土壤及地下水是一个值得深入研究的领域,未来具有广阔的应用前景,本综述为此提供了理论基础。

焦化厂污染土壤中18种PAHs分布特征及健康风险评估

为研究焦化厂土壤中多环芳烃(PAHs)的污染特征及其健康风险,以某焦化厂为目标,布设260个点位,根据各点位污染情况,采集不同深度的土壤样品共780件。通过分析样品中18种PAHs含量,探讨了不同判定标准下厂区土壤中PAHs总体污染程度以及不同功能区污染状况特征,同时根据HJ 25.3—2019《建设用地土壤污染风险评估技术导则》对厂区内18种PAHs进行健康风险评价。结果表明:(1)该焦化厂污染水平较高,且厂区污染在空间上表现出强烈非均质性。厂区内PAHs以2~3环为主,占比为58.82%,4~6环PAHs占比为41.48%。厂区内以苯并[a]芘为基准的6种主要风险PAHs的毒性当量浓度(TEQ Bap)分布特征与总PAHs(∑18 PAHs)含量分布具有一致性。(2)不同功能区表层土壤PAHs含量均值从高到低依次为污水处理区>化产区>焦炉区>锅炉发电厂>煤炭储存区>办公区。不同功能区低环与中高环PAHs含量比值不同,表明各区域污染物来源存在差异。(3)厂区内主要健康风险来源于化合物的致癌风险,不同功能区的致癌风险水平差异较大,污水处理区致癌风险超标倍数及超标率远超化产区及焦炉区。由于苯并[j]荧蒽的加入,PAHs总致癌风险增加0.93%~204.46%,厂区内总致癌风险超标点位增加5个。

Polycyclic aromatic hydrocarbons in soils of Beijing and Tianjin region: Vertical distribution, correlation with TOC and transport mechanism

The contents and distribution of 20 polycyclic aromatic hydrocarbons （PAHs） and heterocyclic aromatic hydrocarbons （HAHs） were investigated in 16 soil profiles of Beijing and Tianjin region. Transport of high molecular weight PAHs （HMWPAHs） and the correlation between total organic carbon （TOC） and their concentrations were also discussed. The results indicated that highly contaminated sites were located at urban or wastewater irrigation areas and pollutants mainly accumulated in topsoil （〈 40 cm）, with a sharp content decrease at the vertical boundary of 30-40 cm. Total PAHs/HAHs concentrations in soils from Tianjin were markedly greater than those from Beijing. Even the contents at bottoms of soil profiles in Tianjin were higher than those in topsoils of Beijing soil profile. HMWPAHs dominated the PAH profiles, exhibiting a uniform distribution of pyrogenic origin between topsoils and deep layers. Furthermore, the percentages of HMWPAHs remained relative constant with the depth of soil profiles, which were consistent with the distribution of particulate matter-associated PAHs in the local atmospheric environments. Therefore, HMWPAHs transport with particulates might be the predominant source found in soil profiles.

Emission characteristics of dioxins,furans and polycyclic aromatic hydrocarbons during fluidized-bed combustion of sewage sludge

Pre-dried sewage sludge with high sulfur content was combusted in an electrically heated lab-scale fluidized-bed incinerator. The emission characteristics of polychlorinated dibenzo-p-dioxins （PCDDs）, polychlorinated dibenzofurans （PCDFs） and polycyclic aromatic hydrocarbons （PAHs） were studied. Coal and calcium oxide （CaO） were added during the sewage sludge combustion tests to optimize combustion conditions and control SO2 emission. The results indicated that the flue gases emitted during mono-combustion of sewage sludge were characterized by relatively high concentrations of SO2, NOx and organic pollutants, due to the high sulfur, nitrogen, and volatile matter content of sewage sludge. The total 16 USEPA priority PAHs and 2,3,7,8-substituted PCDD/Fs produced from sewage sludge combustion were found to be 106.14 μg/m^3 and 8955.93 pg/m^3 in the flue gas, respectively. In the case of cocombustion with coal （msludge/mcoal =1：1）, the 16 PAHs and 2,3,7,8-substituted PCDD/Fs concentrations were markedly lower than those found during mono-combustion of sewage sludge. During co-combustion, a suppressant effect of CaO on PCDD/Fs formation was observed.

Distribution and Source Apportionment of Polycyclic Aromatic Hydrocarbons from Atmospheric Particulate Matter PM2.5 in Beijing

A total of 11 PM2.5 samples were collected from October 2003 to October 2004 at 8 sampling sites in Beijing city. The PM2.5 concentrations are all above the PM2.5 pollution standard （65 μg m^-3） established by Environmental Protection Agency, USA （USEPA） in 1997 except for the Ming Tombs site. PM2.5 concentrations in winter are much higher than in summer. The 16 Polycyclic aromatic hydrocarbons （PAHs） listed as priority pollutants by USEPA in PM2.5 were completely identified and quantified by high performance liquid chromatography （HPLC） with variable wavelength detector （VWD） and fluorescence detector （FLD） employed. The PM2.5 concentrations indicate that the pollution situation is still serious in Beijing. The sum of 16 PAHs concentrations ranged from 22.17 to 5366 ng m^-3. The concentrations of the heavier molecular weight PAHs have a different pollution trend from the lower PAHs. Seasonal variations were mainly attributed to the difference in coal combustion emission and meteorological conditions. The source apportionment analysis suggests that PAHs from PM2.5 in Beijing city mainly come from coal combustion and vehicle exhaust emission. New measures about restricting coal combustion and vehicle exhaust must be established as soon as possible to improve the air pollution situation in Beijing city.

Organochlorine pesticides and polycyclic aromatic hydrocarbons in water and sediment of the Bosten Lake,Northwest China

We evaluated organic pollution in Bosten Lake, Xinjiang, China, by measuring the concentrations and distributions of organochlorine pesticides （OCPs） and polycyclic aromatic hydrocarbons （PAHs）. Water and sediment samples were collected from 19 sites 031-1319） in the lake for analysis. Our analytical results show that the concentrations of total OCPs in water ranges from 30.3 to 91.6 ng/L and the concentrations of PAHs ranges from undetectable （ND） to 368.7 ng/L. The concentrations of total OCPs in surface （i.e., lake bottom） sediment ranges from 6.9 to 16.7 ng/g and the concentrations of PAHs ranges from 25.2 to 491.0 ng/g. Hexachlorocyclohexanes （HCHs） and dichlorodiphenyltrichloroethanes （DDTs） account for large proportions of the OCPs. Low α- to γ-HCH ratios in both water and sediment samples indicate possible contributions from both industrial products and lindane. DDTs in water are probably from historical input, whereas DDTs in sediments are from both historical and recent inputs. Moreover, DDT products in both water and sediments were from multiple sources in the northwestern part of the lake（B11, B12, B13, and B14）. Fugacity ratios for DDT isomers （p,p＇-DDE and p,p＇-DDT） at these sites were generally higher than equilibrium values. These results suggest that the input from the Kaidu River and diffusion of DDTs from the sediment to the water are responsible for DDT pollution in the water. Lower-molecular-weight PAHs, which originate primarily from wood and coal combustion and petroleum sources, represent the major fraction of the PAHs in both water and sediment samples. Our findings indicate that OCPs and PAHs in Bosten Lake can be attributed primarily to human activities. A risk assessment of OCPs and PAHs in water and sediment from Bosten Lake, however, suggests that concentrations are not yet high enough to cause adverse biological effects on the aquatic ecosystem.

Influence of rice straw burning on the levels of polycyclic aromatic hydrocarbons in agricultural county of Taiwan

Atmospheric particulate and polycyclic aromatic hydrocarbons （PAHs） size distribution were measured at Jhu-Shan （a rural site） and Sin-Gang （a town site） in central Taiwan during the rice straw burning and non-burning periods. The concentrations of total PAHs accounting for a roughly 58% （34%） increment in the concentrations of total PAHs due to rice-straw burning. Combustion-related PAHs during burning periods were 1.54-2.57 times higher than those during non-burning periods. The mass median diameter （MMD） of 0.88-1.21 μm in the particulate phase suggested that rice-straw burning generated the increase in coarse particle number. Chemical mass balance （CMB） receptor model analyses showed that the primary pollution sources at the two sites were similar. However, ricestraw burning emission was specifically identified as a significant source of PAH during burning periods at the two sites. Open burning of rice straws was estimated to contribute approximately 6.3%-24.6% to total atmospheric PAHs at the two sites.

Polycyclic aromatic hydrocarbons in surface sediments of the Zhelin Bay in the South China Sea

This study examined the concentrations of polycyclic aromatic hydrocarbons （PAHs） in surface sediments collected in July 2004 from eight stations in the Zhelin Bay, one of the most important bays for large-scale mariculture in Guangdong Province. Thirteen individual parent PAH compounds were identified using high performance liquid chromatography with UV detection. The overall average concentration of total PAHs was 477.0 ng/g, ranging from 146.1 to 928.8 ng/g. Low molecular mass PAHs with two to three rings （e.g., acenaphthene） were dominant in each sample. The PAH concentration varied among sampling stations, with the highest concentration observed at bay outlets and the lowest found at stations outside the bay. Ratios of low to high molecular mass PAHs and fluoranthene to pyrene were used to determine the origin of PAHs, and results indicated mainly petroleum-derived contamination. Compared with other bays and harbors around the world, the total concentrations of PAHs in surface sediments at the Zhelin Bay are moderate, but this does not exclude the possibility of potential impact on human consumers because some strong carcinogenic PAHs with high molecular mass were found at the station with a nearby caged-fish and oyster farm. Long-term monitoring of PAH contamination in the Zhelin Bay is recommended to reduce the potential toxicological effects on aquatic： organisms and humans.

高效液相色谱-内标法测定香辛料中15种多环芳烃类污染物(PAHs)

该研究建立了高效液相色谱(High Performance Liquid Chromatography,HPLC)同时分析香辛料中15种多环芳烃类污染物(Polycyclic Aromatic Hydrocarbons,PAHs)含量的内标检测方法。样品经氢氧化钠溶解,乙腈萃取,正己烷复溶后,过弗罗里硅土(Florisil)小柱净化浓缩,供HPLC检测,苯并[a]芘-D12作为内标定量。该方法在0~100 ng/mL内线性关系良好,辣椒中PAHs检出限:0.5~3.0μg/kg;定量限2.0~10.0μg/kg;花椒中检出限:0.5~1.0μg/kg;定量限2.0~3.0μg/kg。在2.0、10.0、50.0μg/kg 3个浓度水平,辣椒中回收率范围为60.58%~119.48%,相对标准偏差(Relative Standard Deviations,RSD)(n=6)为1.25%~9.61%,花椒中回收率为60.46%~119.24%,RSD(n=6)为1.10%~8.56%。5种地产香辛料中∑PAHs含量由高到低为:青花椒(561.2μg/kg)>二荆条(448.8μg/kg)>红花椒(358.3μg/kg)>石柱红(353.6μg/kg)>小米辣(243.5μg/kg),区县种植基地污染较严重的为璧山、江津和荣昌,∑PAHs分别为721.5、626.6和621.0μg/kg,PAHs中污染较严重的化合物为菲、荧蒽和芘,平均含量分别为215.10、80.25和75.35μg/kg。该研究建立的内标法准确度高,重复性好,适用于香辛料及制品中PAHs检测。

Treatment of tunnel wash waters-experiments with organic sorbent materials.PartⅠ:Removal of polycyclic aromatic hydrocarbons and nonpolar oil

Tunnel wash waters characterize all waters that run off after washing procedures of tunnels are performed.These waters represent a wide spectrum of organic and inorganic pollutants,such as polycyclic aromatic hydrocarbons(PAHs)and toxic metals.Removal of such contaminants from water runoff was investigated using laboratory tests after washing procedure was performed on two road tunnels in eastern Norway(Hanekleiv and Bragernes).Due to diverse character of both,treatment media and treated wash waters, the wh...

Determination of Trace Amount of Polycyclic Aromatic Hydrocarbons in Urban Sewage by Solid-phase Extraction Coupled with High Performance Liquid Chromatograph

[Method] This study aimed to determine trace amount of polycyclic aromatic hydrocarbons(PAHs) in urban sewage by using solid-phase extraction(SPE) coupled with high performance liquid chromatograph(HPLC).[Method] From the aspects of solid-phase extraction column,elution solvent,elution volume,elution speed and so forth,the test conditions of SPE-HPLC method were optimized,and trace amount of PAHs in urban sewage was determined.[Result] The optimized solid-phase extraction conditions were SUPELCLEAN LC-18 solid-phase extraction column,methylene dichloride as elution solvent,15 ml elution volume,2 ml/min elution speed,5 ml/min loading speed,1 000 ml water with 200 ml methanol loading volume.Under the optimized extraction conditions,the recovery was high,namely 76.3%-105.2%;relative standard deviation was 3.8%-6.0%,showing good precision;detection limit was low,only 0.000 8-0.048 0 μg/L.[Conclusion] This method is user-friendly,with high sensitivity and good precision,and suitable for continuous determination of a large volume of water samples.

On-line enrichment and determination of polycyclic aromatic hydrocarbons in atmospheric particulates using high performance liquid chromatography with fluorescence as detector

Seven polycyclic aromatic hydrocarbons （PAHs） in atmospheric particulates were determinated by high performance liquid chromatography （HPLC） with fluorescence detector using direction injection and an on-line enrichment trap column. The method simplified the sample pretreatment, saved time and increased the efficiency. With the on-line trap column, PAHs were separated availably even underground injecting 1.0 ml sample with relatively high column efficiency. The recoveries of the seven PAHs were from 85% to 120% for spiked atmospheric particulate sample. The limit of detection was 15.3-39.6 ng/L （S/N=3.3）. There were good linear correlations between the peak areas and concentrations of the seven kinds of PAHs in the range of 1-50 ng/ml with the correlation coefficients over 0.9970. Furthermore, it also indicated that the method is available to determine PAHs in atmospheric particulates well.