Sorptive domains of pine chars as probed by benzene and nitrobenzene

Chars were generated by pyrolyzing pine wood at temperatures between 300 °C and 700 °C for 6 h and at 500 °C for 10-300 min. Their organic content and surface acidity decreased, and BET surface area increased, with increasing pyrolytic temperature and time. The uptake of benzene and nitrobenzene increased with increasing pyrolytic temperature and time with isotherms characterized by a transition from less to more concave-downward. The isotherms with low-temperature and short-time chars were fitted to the dual Langmuir-partition model, whereas those with high-temperature chars to the dual-Langmuir model. Calculations suggest that the organic phases of chars functioned as partition media and the uptake of benzene and nitrobenzene on carbonized chars occurred first in micropores via pore-filling and later in larger pores through capillary condensation and adsorption. It is concluded that chars may be considered to consist of the partition domain, the high-energy micropores domain and the low-energy large pores domain.     

Predicting molybdenum toxicity to higher plants: Influence of soil properties

The effect of soil properties on the toxicity of molybdenum (Mo) to four plant species was investigated. Soil organic carbon or ammonium-oxalate extractable Fe oxides were found to be the best predictors of the 50% effective dose (ED₅₀) of Mo in different soils, explaining > 65% of the variance in ED₅₀ for four species except for ryegrass (26-38%). Molybdenum concentrations in soil solution and consequently plant uptake were increased when soil pH was artificially raised because sorption of Mo to amorphous oxides is greatly reduced at high pH. The addition of sulphate significantly decreased Mo uptake by oilseed rape. For risk assessment, we suggest that Mo toxicity values for plants should be normalised using soil amorphous iron oxide concentrations.     

Migration of C in the paddy soil-to-rice plant system after C-acetic acid breakdown by microorganisms below the plow layer

Migration of ¹⁴C derived from ¹⁴C-acetic acid was examined by using soils sampled from paddies in four administrative areas in Japan (Aomori, Yamanashi, Ehime and Okinawa) and rice plant in a tracer experiment to understand the fate of ¹⁴C in the paddy soil-to-rice plant system. The loss of ¹⁴C radioactivity levels derived from ¹⁴C-acetic acid was caused by soil microorganism breakdown. A part of the ¹⁴C fixation to soil was caused by microbial assimilation into the fatty acid fraction. ¹⁴C moved upward via two different types of ¹⁴C dynamics in soil: quick movement upward; and constant but slow movement upward. ¹⁴C was highly assimilated into the plant panicle and that was caused by the root-uptake and the transfer of ¹⁴C. Migration of ¹⁴C derived from ¹⁴C-acetic acid relied heavily upon changes of chemical forms and characteristics of ¹⁴C-compound as caused by microorganisms in soil.     

城市大气污染物对PEMFC性能的影响

论述了城市空气污染物(即阴极气体杂质)对质子交换膜燃料电池(PEMFC)性能的影响。提出了燃料电池汽车(FCV)进入商业化应用时即将面临的一个急待研究的课题。文中综述了CO、CO2、硫化物、碳氢化合物(HC)、氮氧化物(NOx)、NH3、卤素离子(X-)、酸沉降物以及大气颗粒物等对PEMFC性能的影响,同时对解决阴极气体杂质影响的途径进行了分析。     

超临界水氧化法处理竹子溶解浆生产废水的实验研究

介绍了利用目前国内最大超临界水氧化中试反应器(2.2L+1.7L)对竹子溶解浆生产废水进行处理的试验,其反应装置处理水量可以达到900~1100L/d。分析了超临界水氧化过程中不同反应温度、时间、压力及其氧气浓度对该废水COD处理效率的影响。实验结果表明:在温度为500℃、压力为24MPa,氧化反应时间为60s时,其COD去除率达到99.2%;氧化反应时间为90s时,其COD去除率达到99.95%。处理后的排水能够达到国家规定的排放标准。同时对超临界水氧化反应过程中出现的反应机理及放热现象进行了探讨。     

阴阳极协同作用降解有机污染物的研究进展

电化学法催化降解有机污染物已引起广泛兴趣。在电极的作用下,电化学反应和化学催化作用结合,可导致有机分子的电催化降解。选用合适的阳极和阴极材料可以加速电化学反应速率,有助于有机物的电化学转化。本文介绍了阳极和阴极氧化有机物的原理,综述了近年来阴阳两极协同作用降解有机物的进展。     

黄河水体石油类污染物生物降解模拟实验研究

采用模拟实验的方法研究了自然条件下石油类污染物的生物降解规律.结果表明,向泥沙含量为0g/L或0.5g/L的黄河水样中加入大约10mg/L的石油类污染物,经过一星期左右的驯化期后,石油降解菌菌落水平逐步升高;当石油类污染物的初始浓度为11.64mg/L,温度为20℃时,泥沙含量为0.5g/L的黄河水样中大约85%的石油类污染物在63d内能得到微生物降解;水体中泥沙的含量和石油类污染物的初始浓度均显著影响石油类污染物的生物降解速率,且在不同时段的影响不一;水体中泥沙的存在亦影响到石油类污染物的生物降解动力学.     

汾河太原段有机污染物检测及评价

采用GC和GC/MS检测手段,定量出汾河太原段有机污染物46种,其浓度在ppb~ppm范围。采用多污染物评价方法,就有机物对健康和生态的潜在危害进行定量评价,结果表明,6个采样点的健康总环境影响度TAS和4个采样点的生态总环境影响度TAS分别大于1,对人体健康和生态有潜在危害。酚类是主要的危害健康污染物。1,4-二氯苯,1,3-二氯苯,萘是主要的危害生态污染物。      

Anaerobic degradation of xenobiotic organic contaminants (XOCs): The role of electron flow and potential enhancing strategies

In groundwater, deep soil layer, sediment, the widespread of xenobiotic organic contaminants (XOCs) have been leading to the concern of human health and eco-environment safety, which calls for a better understanding on the fate and remediation of XOCs in anoxic matrices. In the absence of oxygen, bacteria utilize various oxidized substances, e.g. nitrate, sulphate, metallic (hydr)oxides, humic substance, as terminal electron acceptors (TEAs) to fuel anaerobic XOCs degradation. Although there have been increasing anaerobic biodegradation studies focusing on species identification, degrading pathways, community dynamics, systematic reviews on the underlying mechanism of anaerobic contaminants removal from the perspective of electron flow are limited. In this review, we provide the insight on anaerobic biodegradation from electrons aspect — electron production, transport, and consumption. The mechanism of the coupling between TEAs reduction and pollutants degradation is deconstructed in the level of community, pure culture, and cellular biochemistry. Hereby, relevant strategies to promote anaerobic biodegradation are proposed for guiding to an efficient XOCs bioremediation.     

Evaluating the potential of CNT-supported Co catalyst used for gas pollution removal in the incineration flue gas

This study investigated the use of Cu/Al₂O₃, Co/Al₂O₃, Fe/Al₂O₃, and Ni/Al₂O₃ catalysts for the growth of carbon nanotubes (CNTs). These CNTs were used as support for Co catalyst preparation and Co/CNT catalysts were applied to a catalytic reaction to remove BTEX, PAHs, SO₂, NO, and CO simultaneously in a pilot-scale incineration system. The analyzed results of EDS and XRD showed low metal content and good dispersion characteristics of the Al₂O₃-supported catalysts by excess-solution impregnation. FESEM analyzed results showed that the CNTs that were synthesized from Co, Fe, and Ni catalysts had a diameter of 20 nm, whereas those synthesized from Cu/Al₂O₃ had a diameter of 50 nm. Pilot-scale test results demonstrated that the Co/CNT catalyst effectively removed air pollutants in the catalytic reaction and that there was no obvious deactivation by Pb, water vapor, and coke deposited in the process. The thermal stabilization at 250 °C and hydrophobicity properties of CNTs enhanced the application of CNT catalysts in flue gas.