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。     

Hydrogen sulphide removal from landfill gas

Control of odours should be considered to be a fundamental issue in order to site, design and manage sanitary landfills. With regard to construction and demolition (C&;D) debris, landfilling was the mainly adopted solution in many European Countries; in particular, gypsum drywalls can produce high concentrations of hydrogen sulphide (H₂S) in landfill gas ranging from 7 ppm to 100 ppm. In some cases also dangerous concentrations until to 12,000 ppm were detected. In this paper H₂S removal efficiency in a lab-scale vertical packed scrubber was investigated. Hydrogen sulphide abatement was evaluated for inlet H₂S concentrations of 1000–100–10 ppm, adjusting scrubbing liquid pH in the range 9–12.5 by means of caustic soda (NaOH 2N solution). Moreover, best operating conditions for the system were defined as well as H₂S abatement along the tower and liquid recirculation effectiveness in case of inlet H₂S concentration of 10 ppm (typical odour concentration). Results showed that pH of 11.5 in scrubbing liquid could be considered the best value for removal of different inlet H₂S concentrations, also taking into account parasitical consumption of NaOH due to CO₂ absorption. Moreover, in case of continuous working of the system at H₂S concentration of 10 ppm, strong removal efficiency was already obtained with a packed bed height of about 70 cm. Significant performances were ensured after 1 h of constant activity, consuming about 3 ml of soda per cubic meter of polluted air. Subsequently liquid blowdown was necessary.     

Enhanced carbon tetrachloride degradation by hydroxylamine in ferrous ion activated calcium peroxide in the presence of formic acid

• Complete CT degradation was achieved by employing HA to CP/Fe(II)/FA process. • Quantitative detection of Fe(II) regeneration and HO• production was investigated. • Benzoic acid outcompeted FA for the reaction with HO•. • CO₂•⁻ was the dominant reductive radical for CT removal. • Effects of solution matrix on CT removal were conducted. Hydroxyl radicals (HO•) show low reactivity with perchlorinated hydrocarbons, such as carbon tetrachloride (CT), in conventional Fenton reactions, therefore, the generation of reductive radicals has attracted increasing attention. This study investigated the enhancement of CT degradation by the synergistic effects of hydroxylamine (HA) and formic acid (FA) (initial [CT] = 0.13 mmol/L) in a Fe(II) activated calcium peroxide (CP) Fenton process. CT degradation increased from 56.6% to 99.9% with the addition of 0.78 mmol/L HA to the CP/Fe(II)/FA/CT process in a molar ratio of 12/6/12/1. The results also showed that the presence of HA enhanced the regeneration of Fe(II) from Fe(III), and the production of HO• increased one-fold when employing benzoic acid as the HO• probe. Additionally, FA slightly improves the production of HO•. A study of the mechanism confirmed that the carbon dioxide radical (CO₂•⁻), a strong reductant generated by the reaction between FA and HO•, was the dominant radical responsible for CT degradation. Almost complete CT dechlorination was achieved in the process. The presence of humic acid and chloride ion slightly decreased CT removal, while high doses of bicarbonate and high pH inhibited CT degradation. This study helps us to better understand the synergistic roles of FA and HA for HO• and CO₂•⁻ generation and the removal of perchlorinated hydrocarbons in modified Fenton systems.     

环境空气有组织排放H_2S和CS_2污染源的排查

采用调查和多种检测方法对有组织排放的空气恶臭的物质进行定性分析和定量监测,以证实和确认污染源。在走访受害居民和工业污染源调查的基础上,使用三点比较式嗅袋法、分光光度法、主动式吸附管热解析/GC/MS和不锈钢采样罐/GC/MS法检测空气恶臭的物质的种类和含量,并且通过自动监测仪器长期定点观测污染发生时和消除污染源后空气恶臭的物质含量的变化。结果表明,导致空气恶臭的物质为H2S和CS2,其中CS2为污染源的特征物质,相同时间和地点空气中H2S和CS2的质量浓度相关系数为0.84;污染源下风向空气中H2S含量高,年平均值为0.084mg/m3;不在下风向的空气H2S含量低;清除污染源后其下风向空气中H2S年平均值为0.008 mg/m3,空气不再恶臭。该排查方法为监控有组织排放恶臭的污染源提供了经验和实例。     

大庆石化空气污染区树木叶片内蛋白质、核酸、游离氨基酸及过氧化物酶同工酶含量的变化

石化空气污染区树木叶片内的蛋白质、核酸、游离氨基酸及过氧化物酶同工酶含量较对照区有明显的变化,变化 幅度小的树木的抗污染能力强,变化幅度大的抗污能力弱。其中蛋白质、核酸含量表现出降低,游离氨基酸和过氧化物酶同工酶含量升高。供试的几种绿化树木抗污能力由强至弱依次为云杉、旱垂柳、中东杨、白榆、丁香、白蜡槭。     

高浓度铬对凤眼莲的伤害及膜脂过氧化作用的影响

为了初步探讨在高浓度重金属胁迫下凤眼莲(Eichhornia crassipes)的生理变化,通过急性实验法从活性氧伤害角度探讨铬伤害凤眼莲的机理.结果表明,在高浓度(50ppm)铬污染下,凤眼莲叶片中SOD和CAT活性以及叶绿索α的含量明显下降,组织电解质外渗率和MDA含量明显升高,与对照值之间的差异达显著水平(P<0.05);叶片中H_2O_2含量无明显变化.     

Phenol degradation using combined effects of hydrodynamic cavitation and oxidant: Doehlert matrix

Hydrodynamic cavitation (HC)-based treatments have been proposed for the degradation of phenol as a toxic pollutant. The present work aimed to optimize the degradation of phenol using HC by means of Doehlert experimental design, which has not been previously addressed. Initially, operational parameters of hydraulic characteristics of the pump, inlet pressure, solution pH, and initial concentration were optimized; later, the effects of pH solution and H₂O₂ loading or initial pollutant concentration on phenol degradation were explored using the Doehlert experimental design. It was observed that phenol degradation is strongly dependent on the pH of the solution. Also, the acidic condition favors the formation of hydroxyl radicals and thus, the degradation of phenol. Based on the Doehlert matrix, the 94.1% phenol degradation and 68.60% total organic carbon (TOC) were obtained in 180 min at 304.5 mg/L of hydrogen peroxide at an initial concentration of 20 mg/L, 2.0 pH, and 90 psi inlet pressure, providing a cavitational yield of 6.33 × 10⁻⁶ mg/J and minimum treatment cost of US$/L 0.13. Overall, it has been observed that HC can be a promising route for the removal of pollutants (phenol) effectively using hydrogen peroxide as an additive.     

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.     

An experimental study for H2S and CO2 removal via caustic scrubbing system

In this study, removal of hydrogen sulfide (H₂S) and carbon dioxide (CO₂) from simulated syngas has been studied on one column scrubbing system. Gas flow rate as a measure of gas residence time and superficial gas velocity, gas composition, inlet H₂S load, flow modes (countercurrent and cocurrent) and packing geometry were the parameters in the design and/or operation of an acid gas scrubber system. Better H₂S scrubbing efficiencies have been obtained in countercurrent flow mode than that of cocurrent flow mode. When accordingly designed, static mixer with its superior performance on H₂S removal overweighed to structured packings. The coexistence of CO₂ and H₂S has been shown to increase the sodium hydroxide (NaOH) consumption along the scrubber column thereby decreasing the H₂S removal efficiency at higher H₂S loads. The gas residence time as changing with the gas velocity was found to be more dominant on acid gas removal efficiency than the effect of superficial gas velocity within the experimented range. A gas residence times of equal or above 3 s were seemed to be closer to the optimum point.