光催化降解模拟室内挥发性有机污染物研究

用浸渍-提拉法制备玻璃弹簧负载型TiO2薄膜催化剂,在自制的反应器中进行光催化降解由丙酮、甲苯、对二甲苯组成的模拟室内挥发性有机污染物VOCs研究.研究发现:催化剂中掺杂金属离子能影响催化剂的降解效果,降解效果依次为掺铈TiO2＞纯TiO2＞掺银TiO2;气体流量显著影响降解效果,丙酮、甲苯和对二甲苯的最佳降解流量分别为3、5、7 L/min;混合气体中非对称性的极性分子的降解效率高于对称性分子,导致丙酮、对二甲苯组分降解率降低,甲苯降解率增高.     

不同下垫面苯系物的挥发行为研究

结合石油化工区挥发性污染物泄漏控制的需要,选取淄博地区代表性的砂土、壤土和水3种下垫面,对苯系物的挥发行为进行试验研究,得到了不同类型下垫面中苯系物单组分及其混合物的挥发动力学曲线、最优拟合公式和挥发动力学模型.结果表明,3种下垫面中,苯系物组分及混合物的挥发速率大小依次为:苯>甲苯>BTEX>二甲苯>乙基苯;而苯系物在静水面上的挥发最快,砂土中次之,壤土中挥发最慢.另外,3种下垫面中苯系物的挥发速率常(系)数与蒸气压的关系均呈线性正相关,挥发速率系数随着组分蒸气压的增大而明显增大.下垫面对苯系物挥发的影响机制主要表现为对挥发面积和介质在挥发扩散过程中可利用孔隙通量的影响.     

CuxCe1-xO2/γ-Al2O3催化剂催化燃烧甲苯性能的研究

以γ-Al₂O₃ 为载体,以复合氧化物Cu_xCe_1-xO₂为活性组分,其中,x=0.1,0.2,0.4,0.6,0.8,通过浸渍法制备了一系列Cu_xCe_1-xO₂/γ-Al₂O₃催化剂.在固定床反应器中评价了催化剂对甲苯的催化活性,通过XRD、SEM对催化剂进行表征,并运用ICP-MS分析并计算Cu、Ce的摩尔比以及活性组分的负载量.结果表明,在Cu_xCe_1-xO₂/γ-Al₂O₃催化剂中Cu、Ce摩尔比的实际值与理论值相近,活性组分的负载量在19%以上,而且对甲苯都有较好的低温催化活性,其中当x=0.2时,即Cu_0.2Ce_0.8O₂/γ-Al₂O₃催化剂对甲苯的催化活性最高,其中T₁₀=160 ℃,T₉₀=265 ℃;当甲苯的进口浓度在700~3000 mg·m^-3时,进口浓度对Cu_0.2Ce_0.8O₂/γ-Al₂O₃催化剂的催化活性影响较小,且经过连续80 h的稳定性操作后转化率仍然保持在90%以上.     

自制ZSM-5分子筛对甲苯气体的吸附-脱附性能

考察了自制ZSM-5分子筛对甲苯气体的吸附-脱附性能,并与市售MCM-22分子筛进行了对比实验。实验结果表明:在吸附温度为25℃、进口甲苯质量浓度为840mg/m3、吸附气体流速为0.016m/s、床层高度为15cm的条件下,出口甲苯质量浓度达到0.8mg/m3时的穿透时间为82min,吸附效率为4.26mg/g;在脱附温度为80℃、脱附气体流速为0.016m/s的条件下,脱附35min时出口甲苯质量浓度达到最大,为1220mg/m3。自制ZSM-5分子筛的吸附-脱附性能优于市售MCM-22分子筛。     

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, Macau SAR or in the northern parts of China (Beijing, and Hebei and Shandong). The e ects of di erent 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 e ciencies 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 e ciencies, 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 e ciencies 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 e ect of TCE toward BTEoX bio-removal was observed for BTEoX/TCE mixture, while the inhibitory e ect of TCE toward BTEmX for BTEmX/TCE mixture. The bio-removal e ciency for TPH was shown lower in TPH (2000 mg/L)/TCE (5–50 mg/L) mixtures compared to TPH present alone, implying the inhibitory e ect 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 e ciently at 15 mg/L, probably utilizing BTEX and/or TPH as primary substrates.     

气相抽提法(SVE)去除土壤中挥发性有机污染物的实验研究

研究了土柱直径、土壤粒径和不同污染物等对模拟SVE通风效率的影响.以苯、甲苯、乙苯、正丙苯为污染物进行的实验结果表明,柱底面积/装土高度(S/H)越大,去除率越高.不同粒径受甲苯、乙苯、正丙苯污染的土壤进行的实验结果表明,当土壤粒径由10目变为20～40目后,SVE通风效率降低,污染物去除难度增大.受苯、甲苯、乙苯污染...     

Size distribution and chemical composition of secondary organic aerosol formed from Cl-initiated oxidation of toluene

Secondary organic aerosol (SOA) formed from Cl-initiated oxidation of toluene was investigated in a home-made smog chamber. The size distribution and chemical composition of SOA particles were measured using aerodynamic particle sizer spectrometer and the aerosol laser time-of-flight mass spectrometer (ALTOFMS), respectively. According to a large number of single aerosol diameter and mass spectra, the size distribution and chemical composition of SOA were obtained statistically. Experimental results showed that SOA particles created by Cl-initiated oxidation of toluene is predominantly in the form of fine particles, which have diameters less than 2.5 m (i.e., PM2.5), and glyoxal, benzaldehyde, benzyl alcohol, benzoquinone, benzoic acid, benzyl hydroperoxide and benzyl methyl nitrate are the major products components in the SOA. The possible reaction mechanisms leading to these products are also proposed.     

CuO/zeolite catalyzed oxidation of gaseous toluene under microwave heating

The development of a combined process of catalytic oxidation and microwave heating for treatment of toluene waste gas was described in this work. Toluene, a typical toxic volatile organic compound, was oxidized through a fixed bed reaction chamber containing zeolite-supported copper oxide (CuO/zeolite) catalyst mixed with silicon carbide (SiC), an excellent microwave-absorbing material. The target compound was efficiently degraded on the surface of the catalyst at high reaction temperature achieved by microwave-heated SiC. A set of experimental parameters, such as microwave power, air flow and the loading size of CuO etc., were investigated, respectively. The study demonstrated these parameters had critical impact on toluene degradation. Under optimal condition, 92% toluene was removed by this combined process, corresponding to an 80%–90% TOC removal rate. Furthermore, the catalyst was highly stable even after eight consecutive 6-h runs. At last, a hypothetical degradation pathway of toluene was proposed based on the experimental data obtained from gas chromatography-mass spectrum and Fourier transform infrared spectroscopy analyses.     

日照市夏季VOCs物种空间分布特征及其对臭氧生成的影响

2020年8月22～ 29日期间利用便携式声表面波气相色谱仪(GC-SAW)对日照市区的主要企业源、居民源和道路开展了在线采样分析,获得了大气中多种挥发性有机物(VOCs)的空间分布特征,并对主要组分的化学反应活性进行研究.结果 表明,日照市碳原子大于5的VOCs(VOCC＞5)主要以甲苯、正丙苯和正辛烷为主,且空间分...     

有机沸石对水中BTEX及铬酸根离子的吸附

以天然沸石作为对比物 ,考察了有机沸石对水中BTEX (苯、甲苯、乙苯、二甲苯 )及铬酸根离子的吸附性能 .结果表明 :有机沸石对水中BTEX和铬酸根离子的吸附性能较天然沸石有了很大提高 ,在低质量浓度范围 ( 0— 0 2 5g·l- 1 )内呈现良好的线性关系 .对铬酸根离子的吸附符合Langmuir吸附模型 ,1 5℃时的饱和吸附容量为 1 5 97g·kg- 1 .