劣质催化柴油中多环芳烃选择加氢工艺评价

选取商品柴油加氢精制催化剂和催化柴油选择加氢裂化催化剂,采用N_2吸附-脱附、XRD、TPD、Py-IR等对催化剂进行表征,结果表明,选择加氢裂化催化剂较加氢精制催化剂具有更大的比表面积和孔容,具有更多的中强酸量和较少的弱酸量,并具有更多的B酸中心。以中石化青岛炼化公司生产的高密度、低十六烷值的FCC柴油为原料,对商品加氢精制催化剂和加氢精制/选择加氢裂化组合催化剂进行FCC柴油中多环芳烃选择加氢工艺条件的考察,结果表明,加氢精制催化剂适宜的反应条件为370℃、1.25 h~(-1)、8.0 Mpa,加氢精制/选择加氢裂化催化剂适宜的反应条件为350℃、1.25 h~(-1)、8.0 MPa,组合催化剂的多环芳烃选择加氢效果较好。     

Bioremediation of polycyclic aromatic hydrocarbons: current knowledge and future directions

Polycyclic aromatic hydrocarbons (PAHs) are a class of organic compounds that have accumulated in the natural environment mainly as a result of anthropogenic activities such as the combustion of fossil fuels. Interest has surrounded the occurrence and distribution of PAHs for many decades due to their potentially harmful effects to human health. This concern has prompted researchers to address ways to detoxify/remove these organic compounds from the natural environment. Bioremediation is one approach that has been used to remediate contaminated land and waters, and promotes the natural attenuation of the contaminants using the in situ microbial community of the site. This review discusses the variety of fungi and bacteria that are capable of these transformations, describes the major aerobic and anaerobic breakdown pathways, and highlights some of the bioremediation technologies that are currently available. Copyright © 2005 Society of Chemical Industry     

Rapid determination of heavy polycyclic aromatic hydrocarbons in edible fats and oils

A new rapid method has been developed to determine polycyclic aromatic hydrocarbons (PAHs) in edible fats and oils. Samples are dissolved in isohexane/butylmethylether and PAHs are adsorbed onto a polystyrene solid‐phase extraction cartridge. Triglycerides and non‐aromatic components are eluted stepwise with different mixtures of isohexane and butylmethyether. PAHs finally are eluted with tetrahydrofurane. After evaporation of solvent, PAHs are redissolved in acetonitrile and analysed by RP‐HPLC with fluorimetric detection. Recoveries of 5‐ and 6‐nuclear PAHs are 85—95%, recoveries of 4‐nuclear PAHs are about 60—75%, for 2‐ and 3‐nuclear PAHs the solid‐phase extraction method is not suitable.     

Aerobic biodegradation and inhibition kinetics of poly‐aromatic hydrocarbons (PAHs) in a petrochemical industry wastewater in the presence of biosurfactants

BACKROUND: In Izmir, Turkey, wastewaters from the petrochemical industry are treated using conventional activated sludge systems. A significant proportion of poly‐aromatic hydrocarbons (PAHs) with high‐molecular weights remains in this treatment system and inhibits the biological activity. Biosurfactants increase PAHs degradation by enhancing the solubility of the petroleum components. The aerobic inhibition kinetics of PAHs has not previously been investigated in the presence of biosurfactants for a real petrochemical industry wastewater. RESULTS: Among the kinetic models used (Monod‐type, zero, first‐order and second‐order) it was found that the Monod kinetic was effective for describing the biodegradation of PAHs in petrochemcal industry wastewater in the presence of three biosurfactants, namely Rhamnolipid (RD), Surfactine (SR) and Emulsan (EM) in an aerobic activated sludge reactor (AASR). The maximum PAH removal rate (R_max) and specific growth rate of PAH degrading bacteria (µ_max) increased, while the half saturation concentration of PAH (K_s) decreased at 15 mg L^?1 RD concentration compared with the control without biosurfactant at a sludge retention time (SRT) of 25 days. CONCLUSION: PAH oxidation is typified by competitive inhibition at RD concentrations > 15 mg L^?1 resulting in increases in K_s values with PAH accumulation. Low inhibition constant (K_ID) values reflect difficulties in the metabolizability of PAHs. Metabolite production decreased at RD = 25 mg L^?1 in the PAHs indeno (1,2,3‐cd) pyrene (IcdP), flourene (FLN), phenanthrene (PHE) and benzo(a)pyrene (BaP). Copyright © 2011 Society of Chemical Industry     

煤转化过程中多环芳烃排放的研究现状

发展煤洁净转化技术,减少污染物的排放是煤化工发展方向.目前国内外对减少煤加工过程的CO_2、NO_x、SO_x等污染物的排放研究较多,但对煤加工过程有机污染物多环芳烃(PAHs)的研究还相对不足.本文就多环芳烃的理化性质、起源及其取样和分析方法以及煤加工利用过程中多环芳烃生成与释放的影响因素等有关问题进行了综述和分析,并在此基础上提出进行煤转化过程中多环芳烃的生成与控制研究的思路.     

微生物作用下多环芳烃在土壤中的迁移特征

以菲、蒽和芘为研究对象,通过淋溶实验考察抑菌和未抑菌条件下三者在土壤中的迁移过程,结果表明,微生物的存在抑制PAHs淋出:抑菌条件下180 d时菲、蒽和芘的淋出率分别为8.74%、28.53%和13.56%,未抑菌条件下240 d时菲、蒽和芘的淋出率分别为0.95%、1.47%和0.37%。抑菌和未抑菌条件下3种PAHs均易吸附于表层土壤中:淋滤240 d时,约75%的菲分布在进水端0~2 cm;超过90%的蒽分布在进水端10 cm以内;85%的芘分布在4 cm以内;微生物通过阻滞作用和降解作用影响PAHs的迁移,菲、蒽和芘在土壤中都能被土著微生物降解;60 d以前土柱中PAHs降解以好氧降解为主,60 d以后,PAHs的生物降解转为厌氧降解。     

Quantification of polycyclic aromatic hydrocarbons (PAHs) in the smoke from six woods and comparative study of their distribution

Polycyclic aromatic hydrocarbons (PAHs) are considered as undesirable molecules in smoke. It is important to know the smoke composition applied to meat-based products. PAH extracts of the smoke from five tropical woods were fractionated, analyzed then compared to that of beechwood, a European wood commonly used in the smoking industry of meat-based products. The identification and quantification of the aromatic molecules was carried out with gas chromatography coupled to mass spectrometry (GC/MS).     

Multimedia and Spatial Distribution,Internal Accumulation and Source Diagnostics of Polycyclic Aromatic Hydrocarbons (PAHs) of the Luan River Basin,China

The distribution, composition, and source of 16 polycyclic aromatic hydrocarbons (PAHs) in the Luan River, China, were investigated in this study. The compositional profiles of PAHs in the three mediums represented different characteristics. In different land-use areas, compositional profiles of PAHs in water were familiar, while that in sediment and bank soil presented differences. The spatial distribution of PAHs indicated that the most polluted sites all gathered in the middle and lower reaches of the region, which was different from other rivers in China. The PAH data of bank soil were used for source identification. Both diagnostic ratios of selected PAHs and principal component analysis (PCA) with multiple linear regression (MLR) analysis were studied, suggesting mixed source of PAHs in the Luan River Basin.     

焦化废水中的杂环化合物及多环芳烃降解的研究进展

综述了近年来焦化废水中的杂环化合物和多环芳烃降解的研究进展,总结了物理法的降解研究,归纳了生物法的降解机理,概括了化学法的研究进展,最后指出了焦化废水降解的研究方向。     

Source Allocation of Aliphatic and Polycyclic Aromatic Hydrocarbons in Particulate-Phase (PM10) in the City of Valdivia,Chile

The concentration and signature of n-alkanes (n-C₁₀ to n-C₃₃) and 18 PAHs were determined in air filters across a year period (2010) in an urban area of the city of Valdivia, Chile. Filter samples were extracted using sohxlet apparatus and analyzed by GC-MS techniques. Concentrations of total hydrocarbons ranged from 45–352 ng.m^?3 and total PAHs ranged from 2.93–78.01 ng.m^?3. Concentrations of hydrocarbons during the summer were high (288–352 ng.m^-3) and reduced when the autumn began (45–79 ng.m^?3) to then increase almost linearly to the next summer. The drop in concentration was attributed in part to the significant reduction of traffic when summer ends as tourists leave the city (about 9–15% of the total cars circulating). Results from the chemometric technique of Polytopic Vector Analysis (PVA) indicated three main sources for the alkanes: biogenic (terrestrial plants), signatures of oil combustion, and an unconfirmed source which is thought to come from non specific organic matter degradation. Total PAHs correlated well with total particulate matter with a R² = 0.94. Levels of PAHs in the atmosphere were higher during the winter (6.85–78.01 ng.m^?3) period than the rest of the year (2.93–36.30 ng.m^?3). PVA results indicate three key sources of PAHs and two of those sources derived from oil combustion and biomass burning.     

Chitosan‐coated alginate–polyvinyl alcohol beads for encapsulation of silicone oil containing pyrene: a novel method for biodegradation of polycyclic aromatic hydrocarbons

BACKGROUND: Polycyclic aromatic hydrocarbons (PAHs) are potential hazards in the environment owing to their toxic, carcinogenic and recalcitrant nature. Biodegradation of these compounds, although effective compared with other treatment techniques, is problematic owing to its low aqueous solubility and negligible bioavailability. The present study reports a novel method for biodegradation of PAHs using an encapsulated form of the pollutant in chitosan‐coated alginate–polyvinyl alcohol (PVA) beads. RESULTS: A suitable combination of 3% (w/v) PVA, 100 g L^?1 non‐ionic surfactant Brij 30 and 0.3 silicone oil fraction in the formulation was found to be optimal in the preparation of stable emulsion. The emulsion obtained was admixed with alginate (3% w/v) to prepare suitably sized microspheres by an emulsion gelation technique, which were later coated with chitosan to yield a maximum pyrene encapsulation efficiency of 90.7%. Pyrene in silicone oil at concentration as high as 2 g L^?1, when delivered through the chitosan coated alginate–PVA beads, was completely degraded by Mycobacterium frederiksbergense within 10 days without any significant lag phase. CONCLUSION: Using chitosan‐coated alginate–PVA beads sustained release of pyrene and subsequent biodegradation by M. frederiksbergense were achieved. Using the present system, complete degradation of pyrene was attained even at its very high initial concentration and within a short time period. Further advantage offered by this system seems to be negligible toxic effect of pyrene and solvents on the degrading microorganisms since these were in an encapsulated form and were not in direct contact with the organism. Copyright © 2010 Society of Chemical Industry     

固体废物中多环芳烃萃取的前处理技术及测定方法综述

多环芳烃(PAHs)是环境中广泛存在的一类污染物,其存在于水体、大气及土壤介质中,具有种类多及对环境危害大的特点。近年来,PAHs逐渐成为人们研究的重点,虽然国内外已有PAHs的监测技术的分析标准,但是其提取与测定是一个系统的过程,且不断发展和优化。比较了近年来固体废物(如土壤、污泥等)中PAHs的分析过程中所涉及的萃取、净化及测定方法,总结了各种分析方法的优缺点,介绍了一些新的分析技术。     

Isolation and Identification of Phenanthrene Degrading Bacteria from the Soil around Oil Company of Andimeshk and Investigation of Their Growth Kinetics

Polycyclic aromatic hydrocarbons are particularly important due to large distribution in the environment, high toxicity and their carcinogen and mutagen properties. The purpose of this study was isolation and identification of phenanthrene degrading bacteria from the soil around Oil Company of Andimeshk (Iran) and investigation of their growth kinetics. Sampling from three stations was done at two seasons, spring and summer. Phenanthrene degrading bacteria were isolated from soil using enrichment method. Bacterial identification was performed by biochemical tests and 16S rRNA gene sequencing. Minimum inhibitory concentrations (MIC) were determined at various concentrations of phenanthrene. Bacterial biodegradation rate was determined using HPLC analysis. Finally, the growth kinetics of resistant bacteria was determined with culturing at concentrations of 0.5–0.8 g/l of phenanthrene. According to biochemical and molecular tests Pseudomonas aeruginosa strain SBL, Bacillus cereus strain Z4B-11, Staphylococcus epidermidis, and Micrococcus luteus were identified as phenanthrene degrading bacteria. The results showed that P. aeruginosa SBL and B. cereus Z4B-11 with the greatest amount of MIC are the most phenanthrene resistant bacteria, respectively. These two strains degraded 70% and 50% of phenanthrene after one week of incubation, respectively. The most growth in different concentrations of phenanthrene belonged to P. aeruginosa SBL and B. cereus Z4B-11 while the least growth belonged to S. epidermidis and M. luteus, respectively. It could be concluded that two new strains SBL and Z4B-11 which were isolated in the soil around Oil Company of Andimeshk have relatively high potential to be used for bioremediation of phenanthrene.     

Phytoaccumulation of Benzo[a]pyrene by the Barley in Artificially Contaminated Soil

ABSTRACT

The assessment of toxic effects of polycyclic aromatic hydrocarbons (PAHs) on Haplic chernozems soil was developed by using spring barley (Hordeum sativum distichum) bioaccumulation tendencies. Spring barley was used to estimate the negative effect of chernozemic soil contamination with benzo[a]pyrene (BaP), one the most carcinogenic and mutagenic PAHs compounds. The bioaccumulation tendencies were studied in soil spiking with BaP. Spiked doses were close to technogenic pressure level in studied area, 0–800 µg/kg of BaP. Condition and doses of BaP during 4 years of model experiment influenced morphometric characteristics of spring barley and rates of BaP uptake by plants. Exposure to the growth characteristics containing at least 20 µg/kg BaP promoted absorbing BaP by plants root system as well as increased roots length. Tendencies of phytotoxicity parameters inhibition were observed for all morphometric characteristics of spring barley as energy of germination, length of vegetation part, plant weight and ear height. Quantifiable levels of BaP uptake by spring barley roots exceeded vegetative part more than 2.5 times in all polluted variants. The constant of BaP semi-degradation in artificially polluted Haplic chernozems for 48 months of model experiment T₅₀ reached 1.2–3.4 years. Thus, the BaP uptake by spring barley from chernozem soil contributes to the bioindication responses during environmental monitoring to assess the impact of BaP pollution.     

Evaluation of polyaromatic hydrocarbon removal from aqueous solutions using activated carbon and hyper‐crosslinked polymer (Macronet MN200)

BACKGROUND: Sorption of polycyclic aromatic hydrocarbons (PAHs) on activated carbon and the Macronet polymeric sorbent MN200 was investigated to determine the effectiveness of each sorbent for removal of pollutants from aqueous solution and their possible use as sorbent materials for groundwater. Experiments were carried out to determine the loading capacities of a family of PAHs (acenaphthene, anthracene, fluoranthene, fluorene, naphthalene and pyrene). RESULTS: Activated carbon was the more effective sorbent, with maximum loadings of PAHs between 90 and 230 g kg^?1, while MN200 resin showed values of 25–160 g kg^?1. Loading isotherms based on the Langmuir, Freundlich and Redlich–Peterson models were determined. The hydrophobic character of the pollutants appeared as an important parameter related to the sorption process. Equilibrium and kinetic parameters were used to determine the retardation factors for each PAH. CONCLUSION: The calculated values for the simulation of barrier thickness using both sorbents, taking into account EU requirements for PAHs in groundwater effluent, were perfectly reasonable as a first estimate. The better kinetic properties of MN200 are evident in lower hydraulic residence times and consequently in a lower barrier thickness. Copyright © 2008 Society of Chemical Industry     

Determination of heavy metals and volatile aromatic compounds in used engine oils and sludges

Assessment of contaminant releases during utilization of used oils is essential for the determination of environmental acceptability. These paper reports the results of the study examining a toxic metal leachability from used engine oil and sludge samples employing leaching test (TCLP). The leaching test indicated that lead in oil samples exceeded 5-ppm concentration level what qualified them as a toxic waste. The samples of contaminated sludge were found to contain high concentration of total lead, barium and chromium, but the leaching test showed concentration below regulatory limit. The total content of benzene, ethylbenzene, toluene, and xylenes (BETX), and naphthalene in used oil and sludge samples was also determined and was found not to be a significant factor to contamination.     

C10+重芳烃加氢机理及热力学研究进展

随着国内{\mathrm{C}}_{\mathrm{10}}^{\text{+}}重芳烃产量逐年提升,炼厂对提质增效需求日益高涨,对{\mathrm{C}}_{\mathrm{10}}^{\text{+}}重芳烃高效转化利用技术的需求也日益迫切。由于{\mathrm{C}}_{\mathrm{10}}^{\text{+}}重芳烃富含稠环芳烃,而加氢是稠环芳烃转化为单环芳烃的重要手段,因此,{\mathrm{C}}_{\mathrm{10}}^{\text{+}}重芳烃中代表性芳烃的加氢机理和热力学研究日趋受到重视。本文从{\mathrm{C}}_{\mathrm{10}}^{\text{+}}重芳烃原料性质分析入手,详细阐述了{\mathrm{C}}_{\mathrm{10}}^{\text{+}}重芳烃中代表性芳烃的加氢反应路径及机理、加氢反应热力学的研究进展,以期为实际应用和催化剂开发提供参考。稠环芳烃组成对适宜的加氢反应条件、单环芳烃产品收率、氢耗、反应放热等都有较大影响,为了最大化生产低碳芳烃、降低氢耗,需要根据重芳烃的组成,从原料预切割/预处理、催化剂结构及活性中心、工艺条件这3个方面同时着手进行优化,进而实现对加氢过程的定向调控。     

Platinum catalysts supported on hydrothermally stable mesoporous aluminosilicate for the catalytic oxidation of polycyclic aromatic hydrocarbons (PAHs)

Catalytic oxidation of polycyclic aromatic hydrocarbons (PAHs) was studied over platinum catalysts supported on the hydrothermally stable mesoporous aluminosilicate (SM-41). Naphthalene was chosen as a model reactant of PAHs, due to the simplest and the least toxic PAHs. Zeolite seeds crystallization method was used for synthesis of SM-41. Pt/SM-41 catalyst showed higher activity than Pt/MCM-41 for catalytic oxidation of naphthalene in the presence of 10 vol.% water vapor. Hydrothermal stability and hydrophobicity of Pt/SM-41 must be beneficial for the catalytic oxidation of naphthalene in the presence of water vapor.     

The Effectiveness in the Removal of PAHs from Aqueous Solutions in Physical and Chemical Processes: A Review

Polycyclic aromatic hydrocarbons (PAHs) are relatively well-known organic pollutants and due to their carcinogenic and mutagenic properties, their presence in the aqueous environment still attracts a lot of attention. This article presents a critical review of the literature on the application of physical and chemical processes for removal of PAHs from aqueous solution, including water and wastewater. The effectiveness of coagulation, chemical oxidation, photodegradation, sorption, and membrane processes in the degradation or removal of these micropollutants is described. The PAHs removal efficiency (coagulation ～ 99%, chemical oxidation ～ 87%, photodegradation ～ 93%, sorption ～ 100%, and membrane ～ 100%) during the above processes is difficult to compare due to the works conducted under different conditions and using various mediums, e.g., water, wastewater, PAHs model aqueous solutions.