有机复合填料生物滤床对甲苯气体的净化

利用一种新型有机复合填料作为生物滤床中微生物的附着载体,接种经过驯化筛选的专性甲苯降解菌,填装于生物过滤塔中净化低浓度甲苯气体。研究了新型有机复合填料在长期运行时的情况,考察了进气流量、入口浓度、床层温度和填料湿度对生物滤床的影响,最终经过优化得出,此种填料的生物滤床能够为微生物提供良好的附着生长环境,并能保持滤床的高效稳定运行,当进气流量为0.4 m3/h,入口浓度为400 mg/m3,床层温度为30℃,填料湿度为50%时,生化去除量达到30.6 g/(m3.h),并且在此条件下滤床具有良好的耐冲击性能。     

Mn的氧化价态对Mn／γ-Al2O3催化剂催化臭氧氧化气相低浓度甲苯的影响

采用共沉淀法,以Al2O3为载体制备Mn／γ-Al2O3和Mn—Ce／Mn／γ-Al2O3催化剂,并分别在N2气氛和O2气氛下焙烧。采用固定床连续流动反应器,研究所制备催化剂在室温条件下催化臭氧氧化甲苯的性能。通过XRD、XPS和FTIR等手段对催化剂的结构和组成进行表征。结果表明,Mn／Mn／γ-Al2O3催化剂具有良好的催化臭氧氧化甲苯和催化臭氧自身分解的性能,共沉淀法制备催化剂的最佳Mn负载量为20％。O2气氛焙烧和Ce的加入,可以有效提高催化剂的活性和寿命。原因是O2气氛焙烧和Ce的加入可以提高Mn的氧化价态。催化剂失活的主要原因是有机副产物在催化剂表面吸附堆积,失活催化剂在550℃、空气气氛下焙烧可恢复催化性能。     

生物滴滤塔处理甲苯废气

分别以生物陶粒和聚氨酯泡沫为生物滴滤塔填料,对甲苯废气进行处理,考察不同生物滴滤塔挂膜启动时间以及气体流量和甲苯质量浓度条件下生物滴滤塔对甲苯废气的去除效果。实验结果表明：生物陶粒为填料的生物滴滤塔所需要的挂膜启动时间更短;在气体流量为450L/h时,以生物陶粒为填料的生物滴滤塔甲苯去除率稳定在72%左右,聚氨酯泡沫为填料时甲苯去除率稳定在65%左右。以聚氨酯泡沫为填料时,随甲苯质量浓度提高,甲苯去除率下降幅度较小,甲苯质量浓度为1.80g/m3时,甲苯去除率仍在72%以上。     

无黏结剂ZSM-5分子筛的制备及其对甲苯的吸附性能

以硅溶胶为黏结剂,将粗孔硅胶、聚乙二醇、拟薄水铝石、ZSM-5晶种导向剂捏条成型,采用干胶转化法制备得到了无黏结剂ZSM-5分子筛。XRD和SEM等表征方法的结果显示,采用干胶转化法制备得到的ZSM-5分子筛的相对结晶度较高,具有200nm左右的小晶粒构成的自支撑结构。采用无黏结剂ZSM-5分子筛吸附剂进行甲苯吸附-脱附实验,该吸附剂表现出良好的吸附性能,对甲苯的脱附性能优于活性炭。     

填料塔-微乳液增溶吸收法净化甲苯废气

利用甲苯可以和非离子表面活性剂及相应助表面活性剂水溶液形成微乳液,从而增大甲苯表观溶解度的特性,吸收净化甲苯废气。采用微乳液作为吸收剂的填料塔治理甲苯废气,探讨了吸收剂组成、表面活性剂种类及浓度、喷淋量、甲苯浓度负荷和助表面活性剂的加入及其种类对甲苯去除率的影响。结果表明,微乳液吸收处理甲苯废气具有显著的效果,最大去除率达41%;经过体系筛选采用Tween-20作为表面活性剂,此时最适喷淋量为40 L/h(液气比为1∶5),且随着甲苯浓度负荷的升高,甲苯去除率随之增加;添加助表面活性剂可以不同程度地提高甲苯的去除率,Tween-20/正丁胺/甲苯/水微乳体系为吸收甲苯的最佳体系,此时最高去除率可达65%。     

Biochemical study of retired pentachlorophenol workers with and without following dietary exposure to PCDD/Fs

Objectives

This is the first research study to compare among female, non-smoker workers: (a) the exposure to benzene, toluene and xylenes (BTXs) in urban air during work in the street (traffic policewomen, TP) vs. work in vehicles (police drivers, PD); (b) the exposure to BTXs in urban environments (in street and in car) vs. rural environments (roadwomen, RW); (c) the values of blood benzene, urinary trans, trans muconic acid (t,t-MA) and urinary S-phenylmercapturic acid (S-PMA) in urban areas (in street and in car) vs. rural areas.

Methods

Passive personal samplings and data acquired using fixed monitoring stations located in different areas of the city were used to measure environmental and occupational exposure to BTXs during the work shift in 48 TP, 21 PD and 22 RW. In the same study subjects, blood benzene, t,t-MA and S-PMA were measured at the end of each work shift.

Results

Personal exposure of urban workers to benzene seemed to be higher than the exposure measured by the fixed monitoring stations. Personal exposure to benzene and toluene was (a) similar among TP and PD and (b) higher among urban workers compared to rural workers. Personal exposure to xylenes was (a) higher in TP than in PD and (b) higher among urban workers compared to rural workers. Blood benzene, t,t-MA and S-PMA levels were similar among TP and PD, although the blood benzene level was significantly higher in urban workers compared to rural workers. In urban workers, airborne benzene and blood benzene levels were significantly correlated.

Conclusions

Benzene is a human carcinogen, and BTXs are potential reproductive toxins at low dose exposures. Biological and environmental monitoring to assess exposure to BTXs represents a preliminary and necessary tool for the implementation of preventive measures for female subjects working in outdoor environments.     

流化床微波解吸载甲苯活性炭研究

利用微波作为加热手段,采用椰壳基颗粒活性炭(GAC)为吸附剂,经吸附甲苯达饱和后进行流化床微波解吸实验.结果表明:(1)前4 min,轻微流化状态下的甲苯浓度总体小于中等流化状态;4 min后,轻微流化状态下的甲苯浓度逐渐大于中等流化状态.轻微流化状态下的甲苯解吸效果不理想,与中等流化状态有很大差距.流化床微波解吸适宜...     

活性炭纤维预处理方法对甲苯吸附性能的影响

研究了不同预处理方法下活性炭纤维对甲苯的等温吸附,以评价预处理方法对其吸附性能产生的影响,结果表明:经(1 9)HCl处理的ACF及蒸馏水蒸煮处理过的ACF与未处理的ACF相比,对甲苯的吸附性能有十分显著的提高;处理后的ACF在35℃时的甲苯吸附量仍明显高于未经处理的ACF在25℃下的甲苯吸附量.     

生物滴滤塔处理模拟印刷有机废气

选取甲苯、乙酸乙酯为目标污染物模拟印刷有机废气,采用生物滴滤塔对其进行处理。从某污水处理厂曝气池活性污泥中筛选出3株能够高效降解甲苯、乙酸乙酯的优势菌种,经鉴定分别为枯草芽孢杆菌（Bacillus subtilis）、蜡状芽胞杆菌（Bacillus cereus）和嗜麦芽寡养单胞菌（Stenotrophomonas maltophilia）。实验结果表明：增大乙酸乙酯配比对VOCs去除率影响不大,而增大甲苯配比导致VOCs去除率下降明显;在进气VOCs质量浓度为约800 mg/m³（甲苯与乙酸乙酯的体积比1∶1）、气体空床接触时间为300 s、菌液喷淋量为800 L/h、菌液温度为25 ℃的条件下,VOCs去除率可达约99%。生物滴滤塔运行一段时间后,对菌种进行再鉴定,结果与处理前一致。     

活性碳纤维吸附甲苯废气吸附等温方程的研究

研究了固定床吸附器中粘胶基活性碳纤维(viscose rayon-based ACFs)吸附甲苯废气的特性,通过实验测定活性碳纤维吸附不同浓度甲苯废气的穿透曲线,作出等温吸附曲线,根据实验数据拟合出几个吸附平衡方程,并与实验结果进行比较.实验结果可为工业设备设计提供参考.