呼吸效应对矿井封闭火区氧浓度的影响分析

为避免因火区封闭导致重大安全事故发生，通过采集某矿井1 d内3个不同监测点的大气压力变化情况，建立大气压力波动模型并分析计算，同时建立火区内外压差100，750 Pa情形下的氧浓度模型进而获得火区内侧氧气浓度因呼吸效应，在不同压差、体积大小火区、风阻、瓦斯涌出量、封闭时刻等多因素耦合影响下随时间的变化规律，以评估火区危险性。研究结果表明:井下大气随地面大气周期波动，封闭火区内、外侧之间的气压差因外界大气波动呈现16 h的余弦波动和8 h的线性波动周期变化；密闭质量好的火区具有更好地抗干扰性，内侧氧浓度的降低主要依靠瓦斯稀释；密闭质量差的火区，内侧氧浓度易受到火区涌出瓦斯、外界涌入大气双重影响；火区氧浓度在2%~12%之间波动，以至火区存在发生瓦斯爆炸的可能性；火区内外压差较大时，氧浓度波动变化幅度更大，危险作用持续时间更长。结合火区氧浓度波动模型，可有效地对矿井火区采取安全的防范措施，避免瓦斯爆炸事故发生。     

对氯气校正法测定高氯废水化学需氧量的方法研究

氯气校正法(HJ/T70-2001)是测定高氯废水化学需氧量的国标方法,为了减少样品测定过程带来的环境污染,研究在不改变HJ/T70-2001氧化体系及测试条件的情况下,将取样体积由20 mL减半为10 mL,试剂的使用量相应减半,对方法的检出限、相对误差、相对标准偏差等指标进行验证。结果表明,该方法的检出限符合要求,准确度较高,精密度较好,可用于高氯废水化学需氧量的测定。     

Arbuscular mycorrhiza confers lead tolerance and uptake in Miscanthus sacchariflorus

The effects of an arbuscular mycorrhizal fungi (AMF) association on the growth, survival capabilities, nutrients and lead (Pb) uptake of Miscanthus sacchariflorus under different Pb concentrations were studied in the form of pot cultures. The treatments comprised inoculation or non-inoculation of the AMF, Gigaspora margarita, and the addition of three Pb concentrations to the soil (0, 100 and 1000?mg?kg^?1). The addition of Pb significantly decreased mycorrhizal colonisation. The inoculation of AMF with Pb increased chlorophyll content, Fv/Fm, total dry mass, indole-3-acetic acid (IAA), total nitrogen, and total phosphorus, whereas H₂O₂ level, indole-3-acetic acid oxidase (IAAO) activity, and peroxidase (POD) activity were low compared to those in the non-inoculated treatments. Moreover, the application of AMF together with Pb doses induces concentrations of Pb in the plant, where the higher dose of Pb (1000?mg?kg^?1) induces a lower content of Pb in the aerial part of the plant but a higher content in the root. G. margarita enhanced the tolerance of M. sacchariflorus against Pb toxicity, and facilitated the accumulation of Pb in the plant roots, whereas translocation to the shoots was inhibited at the highest dose Pb (1000?mg?kg^?1). However, in contaminated soil, the Pb removal capability of M. sacchariflorus with AMF was remarkable.     

Catalytic oxidation of CO over Pt/Fe3O4 catalysts: Tuning O2 activation and CO adsorption

• Strong metal-support interaction exists on Pt/Fe₃O₄ catalysts. • Pt metal particles facilitate the formation of oxygen vacancies on Fe₃O₄. • Fe₃O₄ supports enhance the strength of CO adsorption on Pt metal particles. The self-inhibition behavior due to CO poisoning on Pt metal particles strongly impairs the performance of CO oxidation. It is an effective method to use reducible metal oxides for supporting Pt metal particles to avoid self-inhibition and to improve catalytic performance. In this work, we used in situ reductions of chloroplatinic acid on commercial Fe₃O₄ powder to prepare heterogeneous-structured Pt/Fe₃O₄ catalysts in the solution of ethylene glycol. The heterogeneous Pt/Fe₃O₄ catalysts achieved a better catalytic performance of CO oxidation compared with the Fe₃O₄ powder. The temperatures of 50% and 90% CO conversion were achieved above 260°C and 290°C at Pt/Fe₃O₄, respectively. However, they are accomplished on Fe₃O₄ at temperatures higher than 310°C. XRD, XPS, and H₂-TPR results confirmed that the metallic Pt atoms have a strong synergistic interaction with the Fe₃O₄ supports. TGA results and transient DRIFTS results proved that the Pt metal particles facilitate the release of lattice oxygen and the formation of oxygen vacancies on Fe₃O₄. The combined results of O₂-TPD and DRIFTS indicated that the activation step of oxygen molecules at surface oxygen vacancies could potentially be the rate-determining step of the catalytic CO oxidation at Pt/Fe₃O₄ catalysts. The reaction pathway involves a Pt-assisted Mars-van Krevelen (MvK) mechanism.     

石墨烯薄膜原子氧剥蚀行为及电阻特性

目的研究石墨烯薄膜在原子氧空间环境的适应性,为其在航天器上应用提供参考。方法采用刮涂法制备石墨烯薄膜,将石墨烯薄膜材料及石墨烯电阻传感器置于微波源原子氧设备内开展原子氧试验,原子氧剂量分别为3.0×10^20 atoms/cm2和7.5×10^20 atoms/cm^2,研究薄膜表面形貌、结构、成分及电阻性能的变化。结果采用刮涂法可制备氧含量较低的石墨烯薄膜,原子氧剂量为7.5×10^20 atoms/cm^2情况下,石墨烯薄膜的厚度损失为5.3μm,原子氧反应率为7.14×10^-25 atoms/cm^3。原子氧作用后,石墨烯薄膜中碳原子无序程度增大,C—O、—COOH官能团含量降低,C=O官能团含量增加。石墨烯电阻传感器的R0/R比值随原子氧剂量增加线性降低,0.8μm厚度薄膜可探测最大原子氧剂量为5×10^19 atoms/cm^2,增加薄膜厚度有望提高传感器的使用寿命。结论得到了石墨烯薄膜厚度损失、原子氧反应率、微观结构及电阻特性的变化规律,可为石墨烯薄膜的空间应用提供技术支撑。     

模糊控制技术在污水处理中的应用

针对污水处理过程中采用传统的流量程序控制和时间程序控制的不足,提出了一种基于单片机的模糊控制方法。该方法以污水流量、溶解氧(DO)浓度和污泥回流比为主要被控对象,以DO浓度为主要控制参数,通过离散计算和在线查表的模糊推理方法可得到最佳的风机转速,使污水处理生化池内DO浓度保持在最佳状态,同时还通过控制曲线展示了当输入污水流量发生扰动时对DO浓度的控制精度,使污水处理质量保持稳定。通过实际应用表明,该控制方法不但能确保出口净化水水质达标,还可以节约15%的电能。     

空白值校正法无汞快速测定地表水化学需氧量

探讨了K2Cr2O7在不同酸度的硫酸介质中的化学行为,确定9 mol/L H2SO4为K2Cr2O7法测定地表水COD的合理酸度。多种有机物消解试验及半年多地表水样跟踪检测,将消解回流时间从2小时缩短到30分钟之内是可行的。氯离子(Cl-)干扰可用生成AgCl沉淀和空白值校正的办法消除。此方法的检出下限是11mg/L,样品测定的加标回收率在96%～101%。此方法不仅缩短了回流时间、减少了汞带来的二次污染,从而实现无汞快速测定地表水COD。     

沉水植物对沉积物-水界面环境特征的影响

为明确沉水植物对沉积物-水界面环境特征的影响机制,在采自于太湖草、藻型湖区的沉积物柱状样中种植沉水植物后进行破坏性采样,测定沉积物-水界面以上5 cm上覆水的营养盐含量和沉积物的含水量、中值粒径、w(TOC)、w(TON)、w(TP)、金属元素含量等的垂直分布和氧气侵蚀深度.结果表明,种植沉水植物对沉积物-水界面环境特征的影响主要为:①显著降低了上覆水中ρ(PO43--P)[草型湖区上覆水由(7.98±1.85) μg/L降至(4.65±1.16) μg/L,藻型湖区上覆水由(7.86±0.84) μg/L降至(4.89±0.48) μg/L]和草型湖区上覆水中的ρ(DOC)[由(6.64±0.41) mg/L降至(4.73±0.69) mg/L],但没有引起上覆水中ρ(NO3--N)、ρ(NO2--N)和ρ(NH4+-N)的显著差异;②明显提高表层沉积物的含水量,减小草型湖区沉积物表层的中值粒径;③降低草型湖区沉积物表层2 cm内w(TOC)和w(TON),增加草型湖区上层沉积物中w(TP);④明显降低草型湖区沉积物中w(Ca)和w(Mg),但对草、藻型湖区沉积物中的Al,K,Cu,Pb和Zn的含量影响都不明显;⑤藻型湖区沉积物中氧气侵蚀深度由1.6 mm增至3.O mm,草型湖区沉积物则由3.7 mm增至24.0 mm.     

基于微电极技术的反硝化滤池生物膜特性分析

为研究反硝化滤池中溶解氧对反硝化作用的影响,制备性能良好尖端直径在30μm以内的氧(O2)以及硝酸盐(NO3-)微电极,以此为测试工具,对反硝化滤池中生物膜内部O2、NO3-微环境分布进行测试,通过建立扩散-反应方程,获得生物膜微环境耗氧及反硝化活性特征.研究结果表明,溶解氧在生物膜内部呈明显的下降趋势,从主体溶液氧浓度约1mg/L下降至生物膜300μm深度处约为0.生物膜内部反硝化活性区域发生在300~600μm深度范围内.该条件下反硝化滤池生物膜的氧利用速率常数以及反硝化速率常数之间的比值为1.46,溶解氧对反硝化过程的影响是显著的.     

污水生化处理耗氧量计算与应用

根据各类型好氧工艺运行的特点,结合多年设计经验,给出详细计算公式和参数选择范围,说明每个参数含义。