Effect of ignition position on the run-up distance to DDT for hydrogen-air explosions

The method described in this paper enabled reliable and accurate positioning of an overdriven detonation by calculation of shock wave velocities (detonation and retonation) for hydrogen explosions in a closed 18 m long horizontal DN150 pipe. This enabled an empirical correlation between the ignition position and the run-up distance to DDT to be determined. It was shown that the initial ability of the flame to expand unobstructed and the piston-like effect of burnt gas expanding against the closed end of the tube contributed to initial flame acceleration and hence were able to affect the run-up distance to overdriven detonation. Flame speeds and rates of initial pressure rise were also used to explain how these two competing effects were able to produce a minimum in the run-up distance to DDT. The shortest run-up distance to DDT, relative to the ignition position, for this pipe and gas configuration was found when the ignition position was placed 5.6 pipe diameters (or 0.9 m) from the closed pipe end. The shortest run-up distance to DDT relative to the end of the pipe was recorded when the ignition source was placed 4.4 pipe diameters or 0.7 m from the pipe end.     

Nanoparticles in mitigating gaseous emissions from liquid dairy manure stored under anaerobic condition

A number of mitigation techniques exist to reduce the emissions of pollutant gases and greenhouse gases(GHGs) from anaerobic storage of livestock manure. Nanoparticle(NP)application is a promising mitigating treatment option for pollutant gases, but limited research is available on the mode of NP application and their effectiveness in gaseous emission reduction. In this study, zinc silica nanogel(ZnSNL), copper silica nanogel(CuSNL), and N-acetyl cysteine(NACL) coated zinc oxide quantum dot(Qdot) NPs were compared to a control lacking NPs. All three NPs tested significantly reduced gas production and concentrations compared to non-treated manure. Overall, cumulative gas volumes were reduced by 92.73%–95.83%, and concentrations reduced by 48.98%–99.75% for H_2S, and 20.24%–99.82% for GHGs. Thus, application of NPs is a potential treatment option for mitigating pollutant and GHG emissions from anaerobically stored manure.     

Effect of Hydrogen Peroxide on Industrial Waste Water Effluents: A Case Study of Warri Refining and Petrochemical Industry

This paper assessed the composition of waste water effluent generated by a Petrochemical industry and a treatment system developed to improve the quality of the discharge water. Parameters as pH, COD, TSS chloride and lead ions were analysed and treated comparatively using hydrogen peroxide. At pH 8.0 post treatment analysis showed a COD – 96 mg/l TSS – 48 mg/l Cl – 798.75 mg/l and Pb²⁺ – 2 mg/l for treatment D where 40 g/l of alum was used on 30% solution of H₂O₂ compared to systems A-C. Process treatment included activated clay with sodium ion resin which at pH 6.8 had COD – 52 mg/l, TSS – 10 mg/l, Cl – 510 mg/l and Pb²⁺ – 0.070 mg/l. This system has an overall efficiency of 79.0% TSS, 45.83% COD, 97.5% Pb²⁺ and 36.1% Cl reduction. Characteristics obtained for the study has a higher efficiency compared with FEPA and WHO standard for similar industrial water treatment.     

Assessment and optimisation of VOC mass transfer enhancement by advanced oxidation process in a compact wet scrubber

Dimethyl disulphide (DMDS) removal was investigated in a compact scrubber (hydraulic residence time ≈20 ms), composed of a wire mesh packing structure where liquid and gas flow at co-current and high gas superficial velocity (>12 m s⁻¹). In order to regenerate the scrubbing liquid and to maintain a driving force in the scrubber, ozone and hydrogen peroxide were added to water since they allow the generation of nonselective and highly reactive species, hydroxyl radicals HO. Three ways of reagent distribution were tested. The influence of several parameters (liquid flow rate(s), ozone flow rate, pH and reagent concentrations) was investigated. The best configuration was obtained when ozone is transferred in the scrubbing liquid before introduction at the top of the scrubber simultaneously with the hydrogen peroxide solution, allowing to generate hydroxyl radical in the scrubber. With this configuration, DMDS removal could be increased from 16% with water to 34% at the same gas and liquid flow rates in the scrubber showing the potentiality of advanced oxidation process.     

一起双氧水储罐爆炸事故的原因调查

错将水玻璃加到双氧水中,致使双氧水储罐爆炸,炸飞的罐体挂断供电线路,全厂断电停产23 h,经济损失100多万元,无人员伤亡.     

过氧化氢氧化-全自动石墨消解仪消解-阳极溶出伏安法测定海水中总铬

采用全自动石墨消解仪加热、在碱性条件下用过氧化氢氧化海水中的三价铬,优化了极谱法测定条件,方法检出限为0.20μg/L,加标回收率为82.8%~105%,相对标准偏差5%,且对有证标准样品测试的结果符合准确度要求。方法具有选择性好、灵敏度高、准确等特点,适用于海水中总铬的测定。     

Characteristics and origin of the hydrogen sulphide spring water from the Split spa (Southern Croatia)

The objective of this paper is to study the hydrological characteristics and origin of the hydrogen sulphide spring water from the Split spa in Southern Croatia in 1987, 1988 and 2003. This paper presents the results of monitoring the content of chlorides and hydrogen sulphide as well as the temperature of the hydrogen sulphide spring water. Since the hydrogen sulphide content during the dry periods significantly differs from the hydrogen sulphide content during rainy periods, this paper also compares the results obtained for those two periods. Under the influence of great quantities of rainfall during cold periods (winter and the beginning of spring) the ratio between seawater and surface water changes and thus the reduction of chlorides and other minerals occurs. The lowered temperature also reduces hydrogen sulphide which can disappear completely. The concentration of 12‰ chlorides (76–94.4% days/year) and 12 mg/L hydrogen sulphide (66.7–88.9% days/year) has been taken as a limit value between water with a normal typical content and water in cold rainy periods. According to the monitoring results it can be concluded that hydrogen sulphide spring water consists of seawater and hydrogencarbonate surface water with a fairly constant content during dry periods while the hydrogencarbonate content increases during rainy periods.     

离子色谱法测定空气中氟化氢氯化氢和硫酸

以多孔玻板吸收管采样,采用离子色谱法同时测定作业场所空气中的氟化氢、氯化氢和硫酸,采样效率>92%。氟化氢在0 mg/L～2.00 mg/L、氯化氢在0 mg/L～2.50 mg/L、硫酸在0 mg/L～4.00 mg/L范围内线性良好,检出限分别为0.003 mg/m3、0.02 mg/m3、0.023 mg/m3(按采样体积60 L计),标准溶液平行测定的RSD≤8.0%,两个质量浓度水平加标的平均回收率为92.6%～106%。     

Oral administration of potassium bromate, a major water disinfection by-product, induces oxidative stress and impairs the antioxidant power of rat blood

Potassium bromate (KBrO₃) is a widely used food additive, a water disinfection by-product and a known nephrotoxic agent. The effect of KBrO₃ on rat blood, especially on the anti-oxidant defense system, was studied in this work. Animals were given a single oral dose of KBrO₃ (100 mg/kg body weight) and sacrificed 12, 24, 48, 96 and 168 h after this treatment. Blood was collected from the animals and separated into plasma and erythrocytes. KBrO₃ administration resulted in increased lipid peroxidation, protein oxidation, hydrogen peroxide levels and decreased the reduced glutathione content indicating the induction of oxidative stress in blood. Methemoglobin levels and methemoglobin reductase activity were significantly increased while the total anti-oxidant power was greatly reduced upon KBrO₃ treatment. Nitric oxide levels were enhanced while vitamin C concentration decreased in KBrO₃ treated animals. The activities of major anti-oxidant enzymes were also altered upon KBrO₃ treatment. The maximum changes in all these parameters were 48 h after the administration of KBrO₃ and then recovery took place. These results show for the first time that KBrO₃ induces oxidative stress in blood and impairs the anti-oxidant defense system. Thus impairment in the anti-oxidant power and alterations in the activities of major anti-oxidant enzymes may play an important role in mediating the toxic effects of KBrO₃ in the rat blood. The study of such biochemical events in blood will help elucidate the molecular mechanism of action of KBrO₃ and also for devising methods to overcome its toxic effects.     

Synergistic increase in cell lethality by dieldrin and H2O2 in rat thymocytes: Effect of dieldrin on the cells exposed to oxidative stress

Dieldrin, one of persistent pesticides, is highly resistant to biotic and abiotic degradation. It is accumulated in organisms. Recent studies suggest that dieldrin exerts a potent cytotoxic action on cells exposed to oxidative stress. In this study, the effect of dieldrin on rat thymocytes exposed to hydrogen peroxide (H₂O₂)-induced oxidative stress was examined. Dieldrin at 5 μM and H₂O₂ at 300 μM slightly increased cell lethality from a control value of 5.4 ± 0.5% (mean ± standard deviation of four experiments) to 7.8 ± 1.3% and 9.0 ± 0.3%, respectively. Simultaneous application of dieldrin and H₂O₂ significantly increased cell lethality to 46.2 ± 1.8%. The synergistic increase in cell lethality was dependent on dieldrin concentration (0.3–5 μM) but not on H₂O₂ concentration (30–300 μM). Dieldrin accelerated H₂O₂-induced cell death, which was estimated with the help of annexin V-FITC and propidium iodide. Presence of either dieldrin or H₂O₂ decreased the cellular content of nonprotein thiol and increased intracellular Zn²⁺ concentration. The combination of dieldrin and H₂O₂ further pronounced these effects. TPEN, a chelator of intracellular Zn²⁺, significantly attenuated the synergistic increase in cell lethality induced by dieldrin and H₂O₂. It is, therefore, suggested that dieldrin augments the cytotoxicity of H₂O₂ in a Zn²⁺-dependent manner.