Total peroxides in rainwater at two mountainous sites and in Mexico City,Mexico

Rainwater samples were collected in the western sector of Mexico City (MC) and at Rancho Viejo (RV), 80 km west-south-west of MC, from 2001 to 2005, and Orizaba City (OC), about 90 km from the Gulf of Mexico, where rainwater collections were only possible on some weekends in 2001. Rainwater samples were treated in the field, and analysed by fluorescence at the laboratory. The volume-weighted mean concentration (VWMC) of H₂O₂ was 13.2 μM at RV, and 11.2 μM in MC, for the period 2001–2005. The highest VWMC was observed in OC (21.6 μM). The VWMCs for each year were 9.5, 14.4, 11.5, 16.7, and 14.3 μM at RV, and 12.2, 12.2, 14.3, 11.8, and 9.9 μM in MC, for 2001–2005, respectively. Hydrogen peroxide in rainwater correlated significantly and negatively with sulfate in both MC and RV, but not, however, in OC. This study confirmed that H₂O₂ concentration in rainwater is controlled by a complex combination of rain intensity, washout processes and in-cloud formation of H₂O₂, acting simultaneously. This was suggested by the fact that rain intensity seemed to predominate in certain rain fractions of a rain event, while washout processes seemed to predominate in other fractions of the same rain event.     

阻化注浆在硫化矿床自然发火治理中的应用

为治理大厂铜坑矿细脉带硫化矿石自燃火灾,提出喷洒添加NCZ-1型防火阻燃剂的阻化泥浆灭火方法;依据该矿具体条件设计了喷洒工艺流程,测定单位体积阻燃剂用量及各指标气体浓度等参数,研究注浆法在自燃火灾治理中的应用问题。结果表明:该防火阻燃剂在金属矿山火灾治理中效果较好;喷洒阻化泥浆后,环境质量明显改善,主要有害气体SO2浓度减少47.16%;CO2浓度减少了58.49%;阻化期可达14～20天。该试验成果及使用方法对非煤类含硫矿床自燃治理研究有一定借鉴意义。     

阿曼LEKHWAIR油田钻井过程中硫化氢的监控与应急救援

硫化氢是一种剧毒气体,钻井过程中一旦发生硫化氢返出地面,发生泄漏,将会危及员工的生命。阿曼LEKHWAIR油田高含硫化氢,一些区块含量达到三级,在钻井作业过程中存在很大的风险。为此,在该区域钻井除了采取多层次的监控措施、配备三种检测设备,还制定了严格的作业程序以及各种应急救援方案。本文将根据该油田的实际作业情况对硫化氢的监控、防护和应急救援进行介绍。     

Mechanisms of high-pressure hydrogen gas self-ignition in tubes

This paper describes a numerical and experimental investigation of hydrogen self-ignition occurring as a result of the formation of a shock wave. The shock wave is formed in front of high-pressure hydrogen gas propagating in a tube. The ignition of the hydrogen–air mixture occurs at the contact surface of the hydrogen and oxidant mixture and is due to the temperature increase produced as a result of the shock wave. The required condition for self-ignition is to maintain the high temperature in the mixture for a time long enough for inflammation to take place. The experimental technique employed was based on a high-pressure chamber pressurized with hydrogen, to the point of a burst disk operating to discharge pressurized hydrogen into a tube of cylindrical or rectangular cross section containing air. A physicochemical model involving gas-dynamic transport of a viscous gas, detailed kinetics of hydrogen oxidation and heat exchange in the laminar approach was used for calculations of high-pressure hydrogen self-ignition. The reservoir pressure range, when a shock wave is formed in the air that has sufficient intensity to produce self-ignition of the hydrogen–air mixture, is found. An analysis of governing physical phenomena based on the experimental and numerical results of the initial conditions (the hydrogen pressure inside the vessel, and the shape of the tube in which the hydrogen was discharged) and physical mechanisms that lead to combustion is presented.     

CFD modelling of hydrogen release, dispersion and combustion for automotive scenarios

The paper describes the analysis of the potential effects of releases from compressed gaseous hydrogen systems on commercial vehicles in urban and tunnel environments using computational fluid dynamics (CFD). Comparative releases from compressed natural gas systems are also included in the analysis.

This study is restricted to typical non-articulated single deck city buses. Hydrogen releases are considered from storage systems with nominal working pressures of 20, 35 and 70 MPa, and a comparative natural gas release (20 MPa). The cases investigated are based on the assumptions that either fire causes a release via a thermally activated pressure relief device(s) (PRD) and that the released gas vents without immediately igniting, or that a PRD fails. Various release strategies were taken into account. For each configuration some worst-case scenarios are considered.

By far the most critical case investigated in the urban environment, is a rapid release of the entire hydrogen or natural gas storage system such as the simultaneous opening of all PRDs. If ignition occurs, the effects could be expected to be similar to the 1983 Stockholm hydrogen accident [Venetsanos, A. G., Huld, T., Adams, P., & Bartzis, J. G. (2003). Source, dispersion and combustion modelling of an accidental release of hydrogen in an urban environment. Journal of Hazardous Materials, A105, 1–25]. In the cases where the hydrogen release is restricted, for example, by venting through a single PRD, the effects are relatively minor and localised close to the area of the flammable cloud. With increasing hydrogen storage pressure, the maximum energy available in a flammable cloud after a release increases, as do the predicted overpressures resulting from combustion. Even in the relatively confined environment considered, the effects on the combustion regime are closer to what would be expected in a more open environment, i.e. a slow deflagration should be expected.

Among the cases studied the most severe one was a rapid release of the entire hydrogen (40 kg) or natural gas (168 kg) storage system within the confines of a tunnel. In this case there was minimal difference between a release from a 20 MPa natural gas system or a 20 MPa hydrogen system, however, a similar release from a 35 MPa hydrogen system was significantly more severe and particularly in terms of predicted overpressures. The present study has also highlighted that the ignition point significantly affects the combustion regime in confined environments. The results have indicated that critical cases in tunnels may tend towards a fast deflagration, or where there are turbulence generating features, e.g. multiple obstacles, there is the possibility that the combustion regime could progress to a detonation.

When comparing the urban and tunnel environments, a similar release of hydrogen is significantly more severe in a tunnel, and the energy available in the flammable cloud is greater and remains for a longer period in tunnels. When comparing hydrogen and natural gas releases, for the cases and environments investigated and within the limits of the assumptions, it appears that hydrogen requires different mitigation measures in order that the potential effects are similar to those of natural gas in case of an accident. With respect to a PRD opening strategy, hydrogen storage systems should be designed to avoid simultaneous opening of all PRD, and that for the consequences of the released energy to be mitigated, either the number of PRDs opening should be limited or their vents to atmosphere should be restricted (the latter point would require validation by a comprehensive risk assessment).     

Formic acid fractionation towards highly efficient cellulose-derived PdAg bimetallic catalyst for H2 evolution

The present work, in which cellulose isolated from formic acid fractionation(FAC) is decorated with polyetherimide(PEI) to attain highly efficient cellulose-derived PdAgbimetallic catalyst(PdAg-PEI-FAC), has been investigated, and the catalyst properties are characterized by XRD, XPS, BET, ICP-AES and HAADF-STEM. The as-obtained Pd_3.75Ag_3.75-PEI-FAC exhibits excellent catalytic performance for H2 evolution from a sodium formate-free formic acid(FA) aqueous medium at ambient...     

机动车代用燃料性能比较

由于机动车对大气环境污染的贡献率越来越大，以及石油等能源面临枯竭，代用燃料逐渐进人人们的生活，如天然气、甲醇、乙醇、氢燃料和液化石油气等等。这些燃料因其物理、化学性质不同，所表现出来的动力性能、排放性能、经济性能和其他方面（如存储、运输、原料等）也有很大区别。通过比较得出，代用燃料比传统燃料更为清洁，但在其他方面还有待进一步改善。     

采用好氧气提反应器处理含硫化物废水

采用好氧气提反应器处理人工的含硫废水,在ＣＯＤ：Ｓ＾２＝１．５：１,硫化物负荷２－３ｋｇ／（ｍ＾３．ｄ）的条件下,总ＣＯＤ去除率在４０％左右,硫化物扔平均去除率稳定在９５％以上。实验结果表明,气提反应器作为脱硫处理单元是完全可行的,并且具有控制简单,操作方便和启动快等优点,剩余污泥中的含硫量在３７％左右,经过处理,可以回收利用污泥中的硫。     

高级氧化法氧化含邻硝基甲苯废水过程的动力学

研究了水溶液中邻硝基甲苯在有O3或O3／H2O2情况下的氧化反应过程，并建立了动力学模型。在293K、pH值3－10条件下对反应进行测定。实验结果表明，臭氧衰减速率对于O3来说反应级数为1，而对于邻硝基甲苯来说则随pH值变化和H2O3的有无而变化，实验结果与理论预测相吻合。     

γ辐照和H2O2联合作用下五氯酚(PCP)的降解

研究了水溶液中的五氯酚(PCP)在γ辐照和过氧化氢(H2O2)联合作用下的降解.PCP的初始浓度为27.7 mg·L-1,外加H2O2的初始浓度为0、50和100 mg·L-1.结果表明,PCP在不同条件下的辐照降解符合准一级动力学方程.当外加H2O2的初始浓度在0～100 mg·L-1时,PCP的去除率、矿化率和脱氯...