污水样品中NO2-N测定时色度混浊的去除

Al( OH) 3 悬浮液 (按标准方法配制 )与Na OH( 2 5% ) Zn SO4( 1 0 % )两种方法去浊效果好 ,特别是 Na OH Zn SO4可达 1 0 0 %去浊能力。活性炭方法去色能力可达 1 0 0 %。如果采用Na OH Zn SO4 活性炭 ( 0 .2 ml 1 .0 ml 0 .5g)方法则既可脱色又可去浊 ,是测定有色混浊水样的行之有效的方法 ,回收率可达 1 0 2 %。注意事项 :1增加 Al( OH) 3 和活性炭用量 ,在絮凝过滤中 ,NO2 - N易造成滞留现象 ,测定结果偏低 ,回收率仅 85%。 2 Al( OH ) 3 加入量不宜过多 ,每1 0 0 ml水样加 2 ml为宜。污水样品中NO_2-N测定时色度混…     

石化基地大气VOCs大气化学反应活性分析

为了识别独山子石化基地大气VOCs大气化学反应活性和关键活性组份,2013年在研究区内高约25 m的楼顶采用在线的气相色谱仪进行了VOCs观测。结果表明,独山子石化基地大气VOCs的冬季OH消耗速率常数(L~(OH))为29.6×10~(-12)cm~3/分子·s,平均VOCs最大O3增量反应活性(MIR)为248.3 g/g,比乙烯的OH消耗速率常数(0.21×10~(-12)cm~3/分子·s)和最大O3增量反应活性(5.48 g/g)高出149倍和45倍,说明冬季独山子石化基地区域大气中VOCs的大气化学反应活性极强。大气VOCs的OH消耗速率常数(L~(OH))月变化呈现"L"型分布,其中烯烃的OH消耗速率常数(L~(OH))占比最大,占压倒性优势,1月和7月高达90%,其他月份也在70%~85%。冬季大气VOCs最大O_3增量反应活性(MIR)是夏季35倍,只因冬季寒冷且光照弱,使得O_3浓度不高,但导致PM_(2.5)浓度居高不下。     

氢氧自由基与长链烷烃反应产物的气相色谱质谱检测初探

利用烟雾箱系统,以H_2O_2的紫外光解作为OH自由基来源,模拟OH与正十五烷和2,6,10-三甲基十二烷的反应,采用长链烷烃与OH自由基反应产物的Tenax管吸附采样-自动热解析-气相色谱-质谱联用(GC-MS)法分析,获得长链烷烃与OH反应的氧化产物信息,并对长链烷烃与OH的反应机制作初步探讨。     

酚二磺酸法测定地表水中NO_3—N方法的改进

1.样品预处理当Cl~-含量超过10mg.L时,对测定结果产生干扰.在去除Cl~-时,对有些水质样品来说,成分复杂,干扰因素较多,使AgCl的沉淀效果不好.即按“方法”操作,加入Ag_2SO_4后,无论放置过夜或80℃加热絮凝,然后过滤,结果均不理想.经试验加入大量Al(OH)_3使之共沉淀(每100ml水样加Al(OH)_3悬浮液20ml),结果比较好,显色也正常(黄色透明).不过,由此将导致样品体积增大(稀释),最后在测定结果中以相应的稀释倍数即可扣除其影响.     

氢氧化锆共沉淀-二乙基二硫代氨基甲酸银光度法测定天然水中ppb级的无机总砷

常见的二乙基二硫代氨基甲酸银(AgDDC)法,直接取50ml水样测砷,方法检出限为7ppb。通常天然水中含砷量为零点几至几个ppb,此法不能满足环境水中ppb级砷的测定。后来提出新银盐光度法,检出限低达0.36ppb,但需要用多元素分析仪和价格较贵的751型分光光度计,而且方法精密度较难控制。考虑到大多数水质分析实验室配备有廉价的AgDDC法测砷的砷化氢发生器、采用共沉淀富集砷操作简便、分析费用低,因此,我们试验了用Zr(OH)_4作载体,共沉淀水中的无机总砷,使沉淀集中于分液漏斗的底部予以分离,然后用盐酸溶解沉淀,最后用AgDDC光度法测定。当取1000ml水样,加锆60mg,     

还原-偶氮光度法测定水中硝基苯的改进

样品还原后 ,直接用 1 0 % Na OH溶液调节p H 1 .2～ 1 .5 ,待分别加入 Na OH、氨基磺酸胺及N- na溶液以后 ,最后定容显色。如此可与苯胺类测定步骤相一致 ,不易混淆 ,且避免了再调节 p H等操作过程引起的误差。既简化了操作程序又提高了测定结果的准确度和精密度。采用改进后的方法测定了农药和制药废水中硝基苯类含量并同时进行样品加标试验 ,加标回收率 97.6%～1 0 5 % ,结果满意。表明改进后的方法不仅适用于校准曲线制作 ,而且在样品分析中的应用同样可行还原-偶氮光度法测定水中硝基苯的改进@任晓梅$扬州市新城环境监理所!江苏扬…     

1-(2,6-二氯-4-硝基苯)-3-(4-硝基苯)-三氮烯光度法测定矿山废水中的锌

研究了用1-(2,6-二氯-4-硝基苯)-3-(4-硝基苯)-三氮烯(DCNPNPT)分光光度法快速直接测定锌的方法。在表面活性剂TritonX-15的存在下,pH=9.5～10.5的Na2B4O7-NaOH介质中,DCNPNPT与锌( )可生成1∶3的橙黄色络合物。最大吸收波长为445nm,同时在535nm配合物有一最大负吸收,建立以535nm为参比波长,445nm为测定波长的双峰双波长法进行测定,表观摩尔吸光系数可达1.12×105L/(mol·cm)。用拟定的方法测定矿山废水中的锌,与原子吸收法测定的结果十分吻合,结果令人满意。     

2-(2-喹啉偶氮)-4,5-二甲基苯酚光度法测定水中的铜

研究了2-(2-喹啉偶氮)-4,5-二甲基苯酚(QADMP)与铜(Ⅱ)的显色反应,在pH为4 0的HAc-NaAc缓冲介质中,CTMAB存在下,QADMP与铜(Ⅱ)生成分子比为2∶1的稳定红色配合物,该配合物λmax=561nm,摩尔吸光系数ε为4 56×104L·mol-1·cm-1,铜(Ⅱ)含量在0～0 4mg/L内符合比耳定律,该方法用于水样中微量铜的测定,结果满意。     

硫化氢气体监测中样品保存时间的探讨

为使硫化氢样品延长保留时间，加入Fe(OH)2和抽去采集的样品液面上方空气，可使H2S不易氧化而保存样品达72h。     

粗氧丙烷气相色谱分析条件的选择

氯丙醇(PCH)与石灰(Ca(OH)_2)进行皂化反应生成环氧丙烷(PO).由于原料及反应条件等因素的影响,产生了一些副产物,如丙醛(PA)、丙酮(AT)、二氯丙烷(PDC)、表氯醇(ECH)、氯两醇(α、β—PCH)、二氯二异丙醚(DCE)等.对反应产物的定性定量分析,是保证产品质量、工艺废水治理等工作的关键之一.依据《川崎分析指南》介绍的方法进行分析,由于受实验室条件限制,常以不锈钢柱代替原方法中的玻璃柱.虽然通过增加柱长和减小柱口径可尽量减小由此产生的对柱效的不利影响,但实际分析的结果仍不理想,本文对分析条件的选择作了进一步探索.     

Hydroxyl radical generation by electron paramagnetic resonance as a new method to monitor ambient particulate matter composition

Epidemiological studies have demonstrated the relationship between exposure to ambient particulate matter (PM) and health effects in those with cardiopulmonary diseases. The free radical generating activity of particles has been suggested as a unifying factor in the biological activity of PM in toxicological studies but so far has not been applied as a method for environmental monitoring of PM. The purpose of this study was to characterize hydroxyl radical (OH*) production by different size fractions of PM, to use as an alternative method for monitoring of PM composition and activity. We have developed a method, using electron paramagnetic resonance (EPR), to measure OH* radical formation in suspensions of particles in the presence of hydrogen peroxide and 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as a specific spin-trap. Samples of ambient particulate matter (PM) of different size fractions were collected from various sites on various filters. PM deposited on filters as well as suspensions in water retain its ability to generate OH* and this generation is determined by concentration of hydrogen peroxide and soluble metals. However, large variations in OH* radical formation and kinetics were found with different soluble metals and within metals (Fe, V) with different valencies. The method was applied to environmental monitoring in Hettstedt-Zerbst, situated in South-Eastern Germany, where it showed a relation to Cu-content of PM. The method was also applied in Duisburg, where the PMI fraction showed the highest DMPO-OH* generation but was not linked to particle counts. The method integrates metal bioavailability and reactivity and can provide a better understanding of the effect of small variations in mass concentrations on health.     

Direct measurements of urban OH reactivity during Nashville SOS in summer 1999

Emissions of volatile chemicals control the hydroxyl radical (OH), the atmosphere's main cleansing agent, and thus the production of secondary pollutants. Accounting for all of these chemicals can be difficult, especially in environments with mixed urban and forest emissions. The first direct measurements of the atmospheric OH reactivity, the inverse of the OH lifetime, were made as part of the Southern Oxidant Study (SOS) at Cornelia Fort Airpark in Nashville, TN in summer 1999. Measured OH reactivity was typically 11 s(-1). Measured OH reactivity was 1.4 times larger than OH reactivity calculated from the sum of the products of measured chemical concentrations and their OH reaction rate coefficients. This difference is statistically significant at the 1sigma uncertainty level of both the measurements and the calculations but not the 2sigma uncertainty level. Measured OH reactivity was 1.3 times larger than the OH reactivity from a model that uses measured ambient concentrations of volatile organic compounds (VOCs), NO, NO2, SO2, and CO. However, it was within approximately 10% of the OH reactivity from a model that includes hydrocarbon measurements made in a Nashville tunnel and scaled to the ambient CO at Cornelia Fort Airpark. These comparisons indicate that 30% of the OH reactivity in Nashville may come from short-lived highly reactive VOCs that are not usually measured in field intensive studies or by US EPA's Photochemical Assessment Monitoring Stations.     

The role of size exclusion chromatography-flame atomic absorption spectrometry in the treatment chemistry of potable water

The percentage composition of Al13, [AlO4Al12(OH)24(H2O)12]7+, in water treatment coagulants is an important criterion in the development and use of polymeric coagulants. Polymeric coagulants are generally used in cold climates or with highly turbid waters. Size exclusion chromatography flame atomic absorption spectrometry (SEC-FAAS) can separate Al13 and monomeric Al within 6 min. The percentage composition of Al13 and monomeric Al is determined by solving two simultaneous equations. Due to overlapping peaks, a 10% error is associated with this method of quantification. This method can be used on coagulants of varying "r values" (r=[OH-]/[Al3+]), or on mixtures of those coagulants and monomeric aluminium.     

几种烟气脱硫剂的脱硫性能试验

用添加Ｃａ（ＯＨ）２的碱性水,含炉灰渣、赤泥的碱性工业废水及含有Ｆｅ２＋、Ｍｎ２＋催化剂的水溶液作为吸收液;以冷态模拟脱硫洗涤塔为吸收设备,研究了多种脱硫剂的脱硫效果。结果显示,Ｃａ（ＯＨ）２、Ｆｅ２＋、Ｍｎ２＋催化剂对浓度为１０００～２０００ｐｐｍ的ＳＯ２气体有较高脱硫效率;炉灰水、赤泥水对浓度为１０００ｐｐｍ左右的ＳＯ２气体有明显的脱硫效果     

Chemical speciation in natural and brine sea waters

A combined approach consisting of monitoring and thermodynamic modeling was used in order to calculate the concentration of trace element species in water samples of a broad salinity range and to explain their chemical behaviour. The study was performed on water samples (fresh, marine, hyper-saline) taken from the area of Burgas Bay, Bulgaria. The ion association model based on Debye-Hückel theory using the sst2008.dat database and the ion interaction model based on Pitzer theory using a new pit2010.dat database were compared and combined for the purposes of this study. The new pit2010.dat database combines the sst2008.dat database and the pitzer.dat database of the PHREEQCI computer program as well as the thermodynamic data for the elements Fe, Mn, Cu, Zn, Cd and Pb and their Pitzer ion interaction parameters. The results showed that: (1) the predominant species in fresh waters were free ions of Mn(2+) (73.6%), Zn(2+) (58.0%) and Cd(2+) ions (78.3%) as well as carbonate species CuCO?? (81.8%), PbCO?? (77.2%) and hydroxy species Fe(OH) ??(55.2%) and Fe(OH)+?(35.6%); (2) an increase in chloride species MeCl2(n)-(n)(n = 1-4, Me = Mn, Zn, Cu, Pb and Cd) and of the hydroxy species Fe(OH)?? for Fe was calculated for sea and hyper-saline water.     

Carbonate induced dissolution of uranium containing precipitates under cement leachate conditions

The effects of carbonate on uranium (VI) solubility under aerobic and cementitious conditions have been investigated. The information is of relevance to low level nuclear waste disposal. Aqueous NaOH, KOH, Ca(OH)2 and a cement leachate solution were added to uranyl nitrate solution. Afterwards, increasing amounts of ammonium carbonate were added to re-dissolve the precipitates. The precipitates were characterised by means of X-ray powder diffraction (XRPD) measurements and modelling studies. The model calculations were performed using the MINTEQA2 speciation code, with an expanded database incorporating uranium stability constants taken from the HATCHES database. The measured and predicted amounts of CO3(2-) needed to dissolve the precipitates were compared. The knowledge gained from the 'pure' systems was used to rationalise the precipitation and re-dissolution behaviour observed in the leachate system. The lack of uranium solubility at low carbonate levels brought into question literature formation constants for UO2(OH)3- and UO2(OH)4(2-). An approximate log K value of 26.8 for K2U2O7 formation was estimated from the KOH results at pH 12. Generally, uranium solubilities are expected to be insignificant at low level nuclear waste sites because anaerobic conditions should persist. However, this study has demonstrated that solubility in leachate could rise at high pH and high carbonate levels, if aerobic conditions were to develop. Soluble U(VI) species would be formed. The novel part of the study has been to reproduce the effects and to correlate enhanced solubilities with model predictions. Consequently, the study has re-emphasised the need for appropriate environmental monitoring of such sites.     

Measurements of C6-C8 hydrocarbons at a UK rural site during January 1999. Site evaluation and correlations between species

Ambient concentrations of C6-C8 aromatic hydrocarbons and n-heptane, determined by gas chromatography with flame ionisation detection, are presented from a winter campaign during January 1999 at a rural site near Leeds. Absolute concentrations are significantly lower than those obtained from the only designated UK rural site (Harwell) in the automated UK hydrocarbon network. Both absolute and relative concentrations of hydrocarbons measured at the site have been interpreted in terms of the arriving back-trajectories. The site is subject to two main airflows during the winter months; relatively polluted air from the southwest and much cleaner air from the northwest. Ratios of hydrocarbon concentrations show evidence of significant chemical processing consistent with chemical removal by OH. Uncertainties in the ages of the trajectories prevent a reliable estimation of the average OH concentration over the trajectory. The dependence of the variance of the hydrocarbon concentrations with their lifetime with respect to removal by OH does not show the expected behaviour.     

Comparative toxicity of nano-ZnO and bulk ZnO suspensions to zebrafish and the effects of sedimentation, ˙OH production and particle dissolution in distilled water

With the common application of nanoscale zinc oxide (nZnO) and significant potential for its release directly into aquatic environments, it is urgent to carry out research on ecotoxicological impact of nZnO. The characterization of nZnO, the amount of ˙OH in suspensions in the presence of light and the acute toxicity of nZnO and its bulk counterpart suspensions, as well as the acute toxicity of Zn(2+) solution to zebrafish (Danio rerio) at 96 h were studied. It was found that nZnO aggregated into irregular shapes in suspensions, and showed a relationship between its size distribution and concentration. In the presence of light, nZnO suspensions could generate ˙OH, the concentration of which increased with time. Although it was generally thought that ˙OH played a role in the biotoxicity to zebrafish, similar toxicity was observed for the nZnO and bulk ZnO suspensions (96 h LC(50) 3.969 mg L(-1), 2.525 mg L(-1), respectively). Furthermore, the sedimentation of nZnO and bulk ZnO in suspensions, and the accumulation of Zn in zebrafish were studied. The results showed that dissolved Zn(2+), from nZnO and bulk ZnO in suspensions, were toxic to zebrafish, while the aggregation and sedimentation of nZnO suspensions reduced the toxicity of nZnO. However, Zn(2+) may not be the main source of acute toxicity of nZnO and bulk ZnO to zebrafish. The experimental results highlight the importance of a systematic assessment of toxicity mechanisms of metal oxide nanoparticles (NPs) to determine definitively whether their toxicity is caused by nano-effects.     

Impact of ultrasonic treatment on dewaterability of sludge during Fenton oxidation

Fenton oxidation was compared with Fenton oxidation coupled with ultrasonication (Fenton?+?US) for sludge dewatering. Different Fenton reagent (H₂O₂, Fe²⁺) concentrations, pH, and reaction times were studied in different systems on the basis of the specific resistance to filtration (SRF) and capillary suction time (CST). It was found that Fenton?+?US can significantly reduce Fe²⁺ and H₂O₂ dosages and reaction times. After ultrasonication of the system at pH 3, with an ultrasonic frequency of 25 kHz and a sound energy density of 100 W/L, the Fe²⁺, H₂O₂ dosage, and reaction time were reduced by 66.7, 75.0, and 75.0 %, respectively, when compared with Fenton oxidation at the same dewaterability of sludge. The microstructure of sludge and hydroxyl radical (·OH) density in Fenton oxidation and Fenton?+?US was further examined. Fenton?+?US produced more?·?OH in a sludge system than did individual Fenton oxidation. The concentration of?·?OH in Fenton?+?US fell from 79.2 to 6 mg/L over 3.5 h, while the concentration of?·?OH in Fenton oxidation fell from 59.6 to 1 mg/L over 2 h, thus destroying the microstructure of sludge more effectively. Sludge treated using Fenton?+?US for 30 min showed a much thinner and looser microstructure.     

The determination of cobalt(II) at DME using catalytic hydrogen current technique in various water samples, agricultural materials and pharmaceuticals

Two novel and facile ligands ammonium piperidine dithiocarbamate (Amm Pip-DTC) and ammonium morpholine dithiocarbamate (Amm Mor-DTC) were synthesized for the development of rapid and cost effective catalytic hydrogen current technique to analyze cobalt(II) in the presence of NH(4)Cl-NH(4)OH at pH 7.8 and 8.4 with Amm Pip-DTC and Amm Mor-DTC. These ligands produce catalytic hydrogen currents with Co(II) at peak potentials -1.24 V and -1.44 V vs. SCE respectively. Quantitative experimental conditions are developed by studying effect of pH, supporting electrolyte (NH(4)Cl), ligand and metal ion concentrations and effect of adverse ions on peak height to improve the sensitivity, selectivity and detection limits of the catalytic hydrogen current technique and compared it in terms of Student's t test and variance ratio f test with differential pulse polarographic (DPP) method. The developed technique was applied for the analysis of cobalt(II) in various water samples, agricultural materials and pharmaceuticals and the results obtained are in good agreement with the DPP data.