Mechanism of decolorization and degradation of CI Direct Red 23 by ozonation combined with sonolysis

The decolorization and degradation of CI Direct Red 23, which is suspected to be carcinogenic, were investigated using ozonation combined with sonolysis. The results showed that the combination of ozonation and sonolysis was a highly effective way to remove color from waste water. The operational parameters, namely concentration of the dye, pH, ozone dose and ultrasonic density, were investigated during the process. The decolorization of the dye followed pseudo-first-order kinetics. Increasing the initial concentration of Direct Red 23 led to a decreasing rate constant. The optimum pH for the reaction was 8.0, and both lower and higher pH decreased the removal rate. The effect of the ozone dose on the dye decolorization was much greater than that of the sonolysis density. Intermediates such as naphthalene-2-sulfonic acid, 1-naphthol, urea and acetamide were detected by gas chromatography coupled with mass spectrometry in the absence of pH buffer, while nitrate and sulfate ions and formic, acetic and oxalic acids were detected by ion chromatography. A tentative degradation pathway was proposed without any further quantitative analyses. During the degradation, all nitrogen atoms and phenyl groups of Direct Red 23 were degraded into urea, nitrate ion, nitrogen and formic, acetic and oxalic acids, etc.     

In situ studies on the distribution patterns and dynamics of microcystins in a biomanipulation fish--bighead carp (Aristichthys nobilis)

The distribution and dynamics of microcystins in various organs of the phytoplanktivorous bighead carp were studied monthly in Lake Taihu, which is dominated by toxic cyanobacteria. There was a good agreement between LC-MS and HPLC-UV determinations. Average recoveries of spiked fish samples were 63% for MC-RR and 71% for MC-LR. The highest MC contents in intestine, liver, kidney and spleen were 85.67, 2.83, 1.70 and 1.57 microg g-1 DW, respectively. MCs were much higher in mid-gut walls (1.22 microg g-1 DW) than in hind- and fore-gut walls (0.31 and 0.18 microg g-1 DW, respectively), suggesting the importance of mid-gut wall as major site for MC absorption. A cysteine conjugate of MC-LR was detected frequently in kidney. Among the muscle samples analyzed, 25% were above the provisional tolerable daily intake level by WHO. Bighead is strongly resistant to microcystins and can be used as biomanipulation fish to counteract cyanotoxin contamination in eutrophic waters.     

Photoelectrocatalytic degradation of pentachlorophenol in aqueous solution using a TiO2 nanotube film electrode

Titanium dioxide (TiO2) nanotube film electrodes are fabricated by the anodic oxidation method. Scanning electron microscopy (SEM) showed that these tubes were well aligned and organized into high-density uniform arrays. XRD analysis showed the TiO2 nanotubes to be in the anatase crystal form. The TiO2 nanotube film electrode exhibited increased photoelectrocatalytic (PEC) capability compared to a traditional TiO2 film electrode fabricated using the anodizing method for pentachlorophenol (PCP) degradation in aqueous solution. The bias potential, pH value, and electrolyte concentration were shown to be important factors influencing the degradation of PCP by the PEC method using the TiO2 nanotube film electrode as the working electrode.     

Non-aromatic hydrocarbons in surface sediments near the Pearl River estuary in the South China Sea

Surface sediment samples at 4 sites along an offshore transect from outer continental shelf off the Pearl River estuary to the shelf slope region of the northern South China Sea, have been analyzed for total organic carbon (TOC), total nitrogen (TN), solvent extractable organic matter (EOM) and non-aromatic hydrocarbons. TOC, TN and EOM show distinct spatial variations. Their highest values are all recorded at the shelf slope region. EOM varies from 18.70-38.58 microgg(-1) dry sediment and accounts for 0.20-0.72% of the TOC contents. The non-aromatic hydrocarbons are an important fraction of EOM. Their contents range from 3.43-7.06 microgg(-1) dry sediment. n-Alkanes with carbon number ranging from 15-38 are identified. They derive from both biogenic and petrogenic sources in different proportions. Results of isoprenoid hydrocarbons, hopanes and steranes also suggest possible petroleum contamination.     

Biohydrogen production through fermentation using liquid swine manure as substrate

In this paper, continuous production of hydrogen through fermentation with liquid swine manure as substrate was researched using a semi-continuously fed fermenter (8 L in total volume and 4 L in working volume). The pH and temperature for the fermenter were controlled at 5.3 +/- 0.1 and 35 +/- 1 degrees C, respectively, throughout the experiment. Three hydraulic retention times (16, 20, and 24 h) were investigated for their impact on the efficiency and performance of the fermenter in terms of hydrogen yields. The results indicate that hydraulic retention time (HRT) has a strong influence on the fermenter performance. An increasing HRT would increase the variation in hydrogen concentration in the offgas. To produce hydrogen with a fairly consistent concentration, the HRT of the fermenter should not exceed 16 h, which, however, did not appear to be short enough to control methanogenesis because the offgas still contained about 5% methane. When methane content in the offgas exceeded 2%, an inverse linear relationship between hydrogen and methane was observed with a correlation coefficient of 0.9699. To increase hydrogen content in the offgas, methane production has to be limited to below 2%. Also, keeping oxygen content in the fermenter below 1.5% would increase the hydrogen concentration to over 15%. The product to substrate ratio was found to be around 50% for the fermenter system studied, evidenced by the observation that for every 6 liters of manure fermented, 3 liters of pure hydrogen were produced, which was significant and encouraging.     

Comparison of vehicle activity and emission inventory between Beijing and Shanghai

Vehicle emission inventory is a critical element for air quality study. This study created systemic methods to establish a vehicle emission inventory in Chinese cities. The methods were used to obtain credible results of vehicle activity in Beijing and Shanghai. On the basis of the vehicle activity data, the International Vehicle Emission model is used to establish vehicle emission inventories. The emissions analysis indicates that 3 t of particulate matter (PM), 199 t of nitrogen oxides (NO(x)), 192 t of volatile organic compounds (VOCs), and 2403 t of carbon monoxide (CO) are emitted from on-road vehicles each day in Beijing, whereas 4 t of PM, 189 t of NO(x), 113 t of VOCs, and 1009 t of CO are emitted in Shanghai. Although common features were found in these two cities (many new passenger cars and a high taxi proportion in the fleet), the emission results are dissimilar because of the different local policy regarding vehicles. The method to quantify vehicle emission on an urban scale can be applied to other Chinese cities. Also, knowing how different policies can lead to diverse emissions is beneficial knowledge for other city governments.     

建筑物消防系统可靠性分析

为评估建筑物消防系统的可靠性,首先将系统分为探测报警系统和灭火系统等部分,再用事件树法分析事故发生时消防系统不同部分的反应情况.通过贝叶斯理论及历史统计数据得到系统失效率的不确定性概率分布,建立消防系统可靠性随时间变化的数学模型; 用蒙特卡罗方法模拟求得系统可靠性的时间函数并对模型的不确定性参数进行敏感性分析.该方法将统计数据与经验公式、理论方法相结合,并利用蒙特卡罗方法处理模型中的不确定性,不仅能够有效估计消防系统的可靠性,还可对其他类似系统的可靠性进行分析,并通过敏感性分析为进一步减少估计的不确定性提出合理建议.     

多米诺效应的风险分析方法

介绍与分析多米诺效应的相关研究,并针对多米诺效应的定量风险分析,建立了从多米诺场景辨识到后果分析的多米诺效应定量分析方法.通过分析初始事故带来的物理效应对邻近设备的影响,计算了二次设备的损坏概率;分析了多米诺场景,计算了多米诺事故频率,并根据多米诺事故的后果得到个人风险和社会风险曲线.多米诺效应的风险是工业区一个潜在的严重风险,加强多米诺效应的研究对工厂和工业区的安全管理与规划都有重要意义.     

石化企业事故应急预案中的安全防护距离探讨

对石化企业在事故应急预案中安全防护距离的确定给出了各种可以参考的计算方法及参考数据,为企业在事故应急中合理确定安全防护距离提供了决策参考。     

煤矿作业人员防护服装的设计研究

煤矿井下作业人员的防护服装对生产的安全、高效有一定的保障作用.本文在调查和分析了井下作业的环境条件、主要工作内容和动作的基础上,对煤矿井下作业人员的防护服装面料的性能要求和设计要点进行了系统的分析.提出了具体的设计方案.本研究的结果可以为此类功能服装的设计与生产提供参考和借鉴.