Bio-removal of mixture of benzene,toluene,ethylbenzene,and xylenes/total petroleum hydrocarbons/trichloroethylene from contaminated water

Four pure cultures were isolated from soil samples potentially contaminated with gasoline compounds either at a construction site near a gas station in Fai Chi Kei,Macao SAR or in the northern parts of China（Beijing,and Hebei and Shandong）.The effects of different concentrations of benzene,toluene,ethylbenzene,and three isomers（ortho-,meta-,and para-） of xylene（BTEX）,total petroleum hydrocarbons（TPH）,and trichloroethylene（TCE）,when they were present in mixtures,on the bio-removal effciencies of microbial isolates were investigated,together with their interactions during the bio-removal process.When the isolates were tested for the BTEX（50-350 mg/L）/TPH（2000 mg/L） mixture,BTEoX in BTEoX/TPH mixture was shown with higher bio-removal effciencies,while BTEmX in BTEmX/TPH mixture was shown with the lowest,regardless of isolates.The TPH in BTEmX/TPH mixture,on the other hand,were generally shown with higher bio-removal effciencies compared to when TPH mixed with BTEoX and BTEpX.When these BTEX mixtures（at 350 mg/L） were present with TCE（5-50 mg/L）,the stimulatory effect of TCE toward BTEoX bio-removal was observed for BTEoX/TCE mixture,while the inhibitory effect of TCE toward BTEmX for BTEmX/TCE mixture.The bio-removal effciency for TPH was shown lower in TPH（2000 mg/L）/TCE（5-50 mg/L） mixtures compared to TPH present alone,implying the inhibitory effect of TCE toward TPH bio-removal.For the mixture of BTEX（417 mg/L）,TPH（2000 mg/L） along with TCE（5- 50 mg/L）,TCE was shown co-metabolically removed more effciently at 15 mg/L,probably utilizing BTEX and/or TPH as primary substrates.

Occupational Health Risk Assessment of Benzene,Toluene,and Xylene in Shanghai

Objective This study was designed to conduct a retrospective and systematic occupational health risk assessment(OHRA)of enterprises that used benzene,toluene,and xylene(BTX)in Shanghai,China.Methods All data for the study were obtained from 1,705 occupational health examination and evaluation reports from 2013 to 2017,and a semiquantitative model following Chinese OHRA guidelines(GBZ/T 298-2017)was applied for the assessment.Results The selected enterprises using BTX were mainly involved in manufacturing of products.Using the exposure level method,health risk levels associated with exposure to BTX were classified as medium,negligible,or low.However,the risk levels associated with benzene and toluene were significantly different according to job types,with gluers and inkers exhibiting greater health risks.For the same job type,the health risk levels assessed using the comprehensive index method were higher than those using the exposure level method.Conclusion Our OHRA reveals that workers who are exposed to BTX still face excessive health risk.Additionally,the risk level varied depending on job categories and exposure to specific chemicals.Therefore,additional control measures recommended by OHRA guidelines are essential to reduce worker exposure levels.

VAPOR-LIQUID EQUILIBRIUM FOR TERNARY MIXTURES OF BENZENE,TOLUENE,AND p-XYLENE

Vapor-liquid equilibrium composition and temperature were measured for binary andternary mixtures of benzene,toluene and p-xylene at 101.33 kPa The equilibrium cell of Boubliketal.was modified for the present study.The experimental vapor-liquid equilibrium data were corre-lated with the Wilson equation.

Optimizing support acidity of NiMo catalysts for increasing the yield of benzene, toluene and xylene in tetralin hydrocracking

To enhance the yields of benzene,toluene,and xylene in tetralin hydrocracking,the effect of the support acid properties of NiMo catalysts on hydrocracking performance of tetralin were investigated in this study.NaY zeolites were modified by hydrothermal treatment to form USY zeolites at different temperatures and adjust the type and amount of acid.In addition,H-Beta was loaded into the USY to further adjust the acidic properties of the catalysts.The result shows that when the total B acid content of the catalyst is maintained between 150 and 200μmol·g^(-1),the total acid amount is maintained between 1.7 and 1.9 mmol·g^(-1),and the L/B(L and B acids)ratio is maintained between 1.5 and 2,the catalysts have favorable performances on tetralin hydrocracking.Under this condition,the catalysts have a yield of benzene,toluene,and xylene higher than 30 wt%and a selectivity for benzene,toluene,and xylene higher than 35%.The tetralin conversion is greater than 85 wt%.The AB6 catalyst obtains the best hydrocracking effect with the conversion of tetralin reaching 90.24 wt%,the yields of benzene,toluene,and xylene reaching 33.58 wt%,and the selectivity of benzene,toluene,and xylene reaching 37.21%,respectively.

Anaerobic biodegradation of benzene series compounds by mixed cultures based on optional electronic acceptors

A series of batch experiments were performed using mixed bacterial consortia to investigate biodegradation performance of benzene, toluene, ethylbenzene and three xylene isomers （BTEX） under nitrate, sulfate and ferric iron reducing conditions. The results showed that toluene, ethylbenzene, m-xylene and o-xylene could be degraded independently by the mixed cultures coupled to nitrate, sulfate and ferric iron reduction. Under ferric iron reducing conditions the biodegradation of benzene and p-xylene could be occurred only in the presence of other alkylbenzenes. Alkylbenzenes can serve as the primary subs＇rates to stimulate the transformation of benzene and p-xylene under anaerobic conditions. Benzene and p-xylene are more toxic than toluene and ethylbenzene, under the three terminal electron acceptors conditions, the degradation rates decreased with toluene 〉 ethylbenzene 〉 m-xylene 〉 o-xylene〉 benzene 〉 p- xylene. Nitrate was a more favorable electron acceptor compared to sulfate and ferric iron. The ratio between sulfate consumed and the loss of benzene, toluene, ethylbenzene, o-xylene, m-xylene, p-xylene was 4.44, 4.51, 4.42, 4.32, 4.37 and 4.23, respectively; the ratio between nitrate consumed and the loss of these substrates was 7.53, 6.24, 6.49, 7.28, 7.81, 7.61, respectively; the ratio between the consumption of ferric iron and the loss of toluene, ethylbenzene, o-xylene, m-xylene was 17.99, 18.04, 18.07, 17.97, respectively.

Benzene, toluene and xylenes levels in new and used vehicles of the same model

The aim of this work was to determine the level of benzene, toluene, o-xylene and m, p-xylene （BTX） in air samples collected from the cabins of new and used vehicles of the same model. Ten new vehicles were examined in order to check interior emission from materials used to equip the passenger compartment. In order to compare and define the impact of exhaust gases, air samples were also collected from two used cars, at different mileages （up to 20,000 kin）. All vehicles tested were of the same type. Samples were collected onto Carbograph 1TD sorbent, thermally desorbed and examined with the use of gas chromatography with flame ionisation and mass spectrometry detectors. All results obtained were referred to Polish and German requirements for indoor air quality （both in public buildings and in workspace environments）. Average benzene, toluene, o-xylene and m, p-xylene concentrations in new cars were determined at the level of 11.8 μg/m^3, 82.7 μg/m^3, 21.2 μg/m^3 and 89.5 μg/m^3, respectively. In the used cars, BTX concentration increased with increasing vehicle mileage. The most significant increase of BTX concentration was observed above 11,000 km mileage.

Photocatalytic oxidation of gaseous benzene,toluene and xylene under UV and visible irradiation over Mn-doped TiO_(2)nanoparticles

The photocatalytic oxidation of gaseous benzene,toluene and xylene(BTX)over un-doped,0.1 and 1 wt%Mn-TiO_(2)nanoparticles under ultraviolet and visible irradiation was studied in atmosphere of synthetic air or inert gas.The photocatalytic decomposition efficiency and the oxidation products were determined using a Static Photochemical Reactor coupled with FTIR spectroscopy.BTX underwent efficient decomposition over Mn-TiO_(2)photocatalysts under UV irradiation,more with oxygen presence and less without oxygen.More important toluene and xylene went substantial decomposition over 0.1 mol%Mn-TiO_(2)under visible irradiation with oxygen presence.The main final oxidation products in the UV photocatalysis of BTX were CO_(2),CO and H2O,with CO_(2) and CO yields 4 and 2 respectively.The conversion percentage of benzene,toluene,and xylene to CO_(2) were 63.6%,56.4%,51.8%,and to CO 29%,26.5%,23.2%,respectively.In the visible photocatalysis of toluene and xylene the yields of CO were insignificant.Formation of carbon containing deposits on TiO_(2)surfaces was observed after extensive UV photocatalysis of toluene and xylene,and such by-products surface coverage may reduce the photocatalytic activity of TiO_(2)samples.Some aspects of the photocatalytic mechanism were examined.

Effect of benzene,toluene,xylene on the semen quality of exposed workers

Objective To examine the effects on semen and sperm quality of workers after a short and long term exposure to benzene, toluene, and xylene Methods The semen and blood of 24 married workers exposed to benzene, toluene, and xylene from shoemaking, spray painting, or paint manufacturing factories were collected The concentration of benzene, toluene, and xylene in the blood and semen was determined by using headspace chromatographic method Routine sperm test was carried out and acrosin activity detected Results The results showed that benzene, toluene, and xylene were found in the blood and semen of some ex workers in a working environment where the air concentration of benzene, toluene, and xylene exceeded the maximum allowable concentration (MAC) This result was not found in workers of the control group There were also some effects on the quality of semen in the exposed workers For example, the percentage of semen with liquefaction time exceeding 30 minutes increased The sperm vitality, motility and acrosin activity decreased At the same time, there were a positive correlation between liquefaction time and the level of toluene in semen, and a negative correlation between sperm vitality, sperm activity or acrosin activity and working history Conclusions The results suggested that the mixture could affect the quality of semen and sperm, which might be the main reason of the abnormal pregnancy outcome among the wives of workers exposed to benzene, toluene, and xylene Further studies are, however, required to confirm these findings

Indoor and outdoor BTX levels in Barcelona City metropolitan area and Catalan rural areas

Five aromatic hydrocarbons (benzene, toluene, and three isomeric xylenes) were monitored in indoor and outdoor air of 7 public buildings and 54 private homes, located in Barcelona City metropolitan area and in several rural areas of Catalonia. The sampling was carried out over four periods: spring-summer and winter of 2000, and summer and winter of 2001. Passive ORSA 5 Dra¨ger samplers were used for benzene, toluene, and xylenes (BTX) adsorption. BTX were extracted with carbon disulphide and analysed using ...

硫化物双功能催化剂上四氢萘加氢裂化制备BTX反应动力学和选择性研究

在反应温度400℃和反应压力6 MPa条件下,在Beta分子筛负载不同加氢活性中心(Co、Mo、Ni和W)的硫化物双功能催化剂上对四氢萘选择性加氢裂化(HDC)制备苯、甲苯和二甲苯(BTX)反应行为进行研究。通过建立四氢萘加氢裂化反应的九集总反应动力学模型,结合各反应速率常数,探讨不同双功能催化剂的反应性能。研究表明:NiW(Ni(5)W(20)/Beta-40)和NiMo(Ni(5)Mo(20)/Beta-40)催化剂中,Beta分子筛载体上活性金属和酸中心含量高,在四氢萘转化率分别为98%和96%时,表现出较高的BTX选择性(63%和56%,摩尔分数)。结合反应结果和反应速率常数数据可以发现:虽然Ni(5)W(20)/Beta-40和Ni(5)Mo(20)/Beta-40催化剂上积炭速率高,但是BTX生成速率与BTX过度加氢裂化反应速率的比值、BTX生成速率与催化剂积炭速率的比值也都高于其他催化剂,表现出优异的BTX选择性。

Production of BTX through Catalytic Depolymerization of Lignin

Lignin is the only nature renewable resource which can provide large quantities of aromatic compounds. In the work, transformation of lignin into benzene, toluene, and xylenes （BTX） was investigated over the HZSM-5, HY, and MCM-22 catalysts, and the HZSM-5 catalyst showed the highest carbon yield of BTX. The reaction condition, including temperature, the gas flow rate, and the catalyst/lignin ratio, was also investigated. The carbon yield of BTX reached about 25.3 C-mol% over HZSM-5 catalyst under T=550℃, f（N2）=300 cm^3/min, and catalyst/lignin ratio of 2.

Seasonal and Spatial Variation of BTEX in Ambient Air of Delhi

The present study aims to provide an indication of ambient levels of BTEX in the immediate vicinity of petrol filling stations in Delhi & other road side corridors of Delhi. In this study spatial and seasonal variation of BTEX has been measured at different locations in Delhi. For the measurement of VOCs, passive based diffusion methodology was adopted for the adsorption of BTEX over the activated charcoal. Four categories of sampling sites were chosen (residential, traffic junctions, road side corridors and petrol pumps). The result confirms that the aromatic concentrations in the ambient air of gas stations are appreciably higher than the average values in locations with high vehicular flux. The mean concentration of BTEX at all the locations was 0.622μg/m3, 0.361 μg/m3, 1.037 μg/m3 and 0.122 μg/m3. The average concentration of benzene was highest at petrol pump 3.5 μg/m3 however at all other sampling sites it was in the range of 0.294 to 0.712 μg/m3. The mean concentration value shows that the xylene concentration dominates more in Delhi as compared to benzene. The total average BTEX concentration at road side corridors was 0.594 μg.m-3, at residential corridors was 0.262 μg.m-3, at intersections it was 0.649 μg.m-3 and at petrol filling stations it was 1.457 μg.m-3. The concentration was in the order of petrol filling stations > intersections > road side corridors > residence. These data show the predominance of diesel driven vehicles in Delhi since xylene mainly comes from diesel exhausts. The influential VOC species in case of diesel engine exhaust are benzene, ethylbenzene, xylenes, propane, n-decane and undecane and in case of gasoline vehicle exhaust influential species are benzene, ethylbenzene, 1,2,4-methylbenzene, 1,3,5-methylbenzene, n-hexane and 2-methylhexane. So xylene is mainly coming from diesel exhaust since gasoline vehicle exhaust doesn’t show this species.

基于气质联用法的鞋用胶粘剂中6种苯系物的测定

建立了气质联用法测定鞋用胶粘剂中6种苯系物的分析方法。以乙酸乙酯为萃取溶剂,提取胶粘剂中的6种苯系物,优化了仪器分析条件。结果表明,本方法6种苯系物的检出限为35~65 mg/kg,加标回收率为91.9%~98.0%,相对标准偏差为3.8%~7.8%。本方法仪器分析时间短,回收率高,重复性好,结果可靠,适用于胶粘剂中6种苯系物的检测。

C9^+重芳烃增产BTX技术进展

随着我国芳烃联合装置及大规模乙烯装置的兴建及扩能改造,副产的C_9^+重芳烃会越来越多,通过芳烃增产技术将低附加值C_9^+重芳烃转化为苯、甲苯、二甲苯(BTX)轻质芳烃对于促进企业挖潜增效、拓展芳烃原料来源具有重要意义。本文以重整C_9^+重芳烃和裂解C_9^+重芳烃增产BTX为出发点,从反应原理、工艺、催化剂及优缺点等方面对热加氢脱烷基、催化加氢脱烷基、非临氢脱烷基、两段临氢裂解技术进行概述,并对技术的发展趋势进行了展望。指出目前无论是重整C_9^+重芳烃增产BTX技术,还是裂解C_9^+重芳烃增产BTX技术均存在许多问题,需要通过从工艺方面或催化剂方面进行创新改进,以提升技术的经济性。催化材料是技术创新发展的关键,未来研发方向应综合反应机理、催化剂失活机理、工艺工程等问题开发高效的新型催化材料,促进C_9^+重芳烃增产BTX技术的创新发展。

木材经催化热分解向BTX和合成燃料的转化

以废木材生物质的有效利用为目的 ,使用粉粒流化床反应器 ,对 3种木材进行了催化热分解实验 ,以 4种催化效果不同的粒子作为流化床内的流化介质来考察催化热分解过程中介质颗粒、反应气体和热分解温度对产物分布的影响 .木材的挥发性物质在 70 0K时就已几乎分解出来 ,挥发性物质中的轻质芳香烃碳氢化合物(苯、甲苯、二甲苯和萘 :BTXN)的收率随着热分解温度的升高而增加 ,1173K下达到 3 1% (质量分数 ) ,daf.在氢气气氛下 ,当作为流化介质颗粒Zn (3% ,质量分数 ) /HZSM 5催化剂对木材进行催化热分解时 ,85 3K下可得到 6 1% ,daf的轻质芳香烃碳氢化合物的收率 (BTX 5 5 % ,daf、萘 0 6 % ,daf) .而在活性很高的Ni Mo A加氢催化剂下 ,在 86 3K时 。

安顺市酒店(宾馆)室内空气苯系物来源及监测结果分析

为了解安顺市酒店(宾馆)中苯系物污染现状及主要来源,规范酒店(宾馆)中苯系物含量标准和制定防控措施提供数据与基础,该文随机抽取安顺市24家不同级别的酒店(宾馆)作为监测对象,根据GB/T 18883—2022《室内空气质量标准》来确定采集点的要求,使用PID-Analyzer Mobile便携式GC-PID分析仪对各样本进行检测;定量资料使用中位数与四分位数间距进行统计描述;计数资料组间比较采用卡方分析检验。室内苯系物检出率分别为苯11.11%、甲苯13.89%、二甲苯未检出;对于检出苯系物的7个样本进行分析,42.86%的样本苯来源于室内,28.57%的样本甲苯来源于室内,14.29%的样本二甲苯来源于室外。当前安顺市酒店(宾馆)苯系物污染程度较轻,检测结果合格率较高;苯与甲苯主要来源于室内,二甲苯主要来源于室外。

催化裂解制低碳烯烃技术研究进展

成品油需求逐渐达峰,炼油向化工转型不断深化与演变,“降油增化”已成为炼油化工产业转型发展的共识,以乙烯、丙烯为主要产物,并副产苯-甲苯-二甲苯混合物(BTX)的催化裂解将成为化工型炼油厂的核心技术。基于催化裂解技术原料的不同,综述了国内外重质馏分油、轻质馏分油及原油催化裂解技术研究进展,介绍了现有催化裂解技术的主要专利商及专利技术,重点阐述了不同催化裂解技术的主要技术特征、反应器类型、工艺操作条件、配套硬件设备和工业推广应用情况等,并着重对比了不同技术的工业应用效果,包括反应原料、主要产物分布、目标产品乙烯、丙烯等低碳烯烃收率和BTX收率等。同时,针对现有技术存在的主要问题及研发进展,从强化基础理论研究、增强催化裂解技术原料适应性与产品结构灵活性等方面提出了催化裂解技术未来研究方向与建议。

对二甲苯结晶相关三元和四元体系固液相平衡数据预测

针对对二甲苯结晶相关的由C_(8)芳烃、甲苯和苯组成的三元和四元固液相平衡体系,选取固液相平衡计算模型—Van′t Hoff方程简式,预测了对二甲苯-乙苯-苯、邻二甲苯-乙苯-苯和间二甲苯-乙苯-苯三元体系,以及对二甲苯-间二甲苯-乙苯-甲苯、对二甲苯-邻二甲苯-乙苯-甲苯、对二甲苯-间二甲苯-乙苯-苯、对二甲苯-邻二甲苯-乙苯-苯和间二甲苯-邻二甲苯-乙苯-苯四元体系固液相平衡数据。结果表明:Van′t Hoff方程简式适用于对二甲苯装置对二甲苯结晶相关体系中由C_(8)芳烃、甲苯和苯组分组成的三元和四元固液相平衡体系计算;利用三元和四元体系固液相平衡数据可绘制各体系的固液相平衡相图,为对二甲苯结晶相关的由C_(8)芳烃、甲苯和苯组分组成的体系固液相平衡数据测量和有关研究、设计、模拟优化提供理论指导和依据。

紫外分光光度法测定焦化厂废水中苯系物的探究

针对采用气相色谱法测定焦化厂废水中苯系物含量时分析成本高、对分析人员要求高等问题,青海盐湖镁业有限公司采用紫外分光光度法进行替代研究。结果表明:采用紫外分光光度法测定苯标准工作液时的最大相对误差为4.0%;相对于气相色谱法对未知水样的测定结果,紫外分光光度法测定结果的最大相对误差为11.11%;紫外分光光度法测定焦化厂废水时的加标回收率在95%~105%,对同一样品重复测定5次时的相对标准偏差为0.85%。

拉曼光谱分析技术在化工生产中的应用探析

利用拉曼光谱对间二甲苯和对二甲苯的特征波段进行了测定,并对该波段进行了拉曼定量测定。以991、785、1052、536、827 cm-1为定量峰,并绘制了其工作曲线。经t检验,结果表明,本方法的准确度达到了95%。经测定,该方法的回收率在94.60%~104.15%之间。