长江、黄河水中硝酸态氮的测定

对于水系,硝酸态氮和其它氮氧化物是重要的污染物。硝酸态氮是含氧化合物中的最高价形态。由于硝酸盐在一定条件下能被还原成亚硝酸盐,而亚硝酸盐有致癌作用,所以规定饮用水中硝酸态氮的含量<10mg/l。由于大多数硝酸盐均易溶于水,NO_3离子中的氮在不同情况下可被还原成不同价态,以及缺少稳定的络合物,这些都给硝酸态氮的测定带来一定困难。国内测定硝酸态氮的方法有:     

水中硝酸盐氮和亚硝酸盐氮的测定

水中硝酸盐氮和亚硝酸盐氮的测定姚野梅，李锦才，周冬香，李飞燕（上海水产大学食品学院上海２０００９０）硝酸盐是水生生物营养盐之一，在养殖水的无机氮中占较大比例，它是含氮化合物的最终氧化产物。硝酸盐的含量反映着养殖水质环境质量，硝酸盐的过量积聚将促使水体...     

硫酸铵溶液中硝酸盐氮和亚硝酸盐氮的测定

氨法脱硫后的硫酸铵溶液的成分复杂,干扰物质较多,亚硝酸盐氮的含量较低。针对溶液的特点,本文采用紫外分光光度法测定此溶液中的硝酸盐氮和亚硝酸氮含量。实验结果表明,本方法操作简单,可快速准确地测定硝酸盐和亚硝酸盐中的氮含量,精密度和重现性较好,可用于在线测定。     

水中三种无机氮转化关系探究

生活用水中亚硝酸盐、硝酸盐和氨氮含量与人们健康息息相关。研究不同的水体、煮沸时间和沸水放置时间对无机氮含量影响,可更好的探索水中无机氮转化关系。实验结果表明:不同水体中无机氮含量不同,雨水的含量最高,其亚硝酸盐为0.11 mg/L;随着煮沸时间的增加,亚硝酸盐和硝酸盐呈增长趋势,而氨氮呈下降趋势,其减少量比亚硝酸盐和硝酸盐增加量大1.7%。煮沸1 min和30 min的自来水,亚硝酸盐含量分别为0.014 mg/L和0.046 mg/L。沸水放置1天后,亚硝酸盐的含量达到最大并在3天后趋于稳定,其中煮沸30 min含量分别为0.053 mg/L。水中无机氮转化关系为水中的氨氮在微生物、能量和溶解氧作用下先被氧化成亚硝酸根,部分亚硝酸根再被氧化成硝酸根。     

有机碳源添加对脱氮副球菌脱氮效果的影响

以脱氮副球菌(Paracoccus denitrificans)为菌种来源,可生物降解聚合物PCL为有机碳源和生物膜载体,对养殖水体的硝酸盐氮进行脱除实验。结果表明,以特定反硝化菌株接入反硝化装置,可以有效去除硝酸盐氮和亚硝酸盐氮。经过15 d的驯化,60 d的反硝化实验,硝酸盐氮的去除率达到79%,且无亚硝态氮的明显累积;扫描电镜结果表明,固相碳源表面形成的凹陷可为脱氮副球菌提供碳源及载体,具有较好的生物利用性。以PCL为碳源,可以提高养殖水体中的C/N,且操作简单,在经济上具备一定的可行性。     

催化光度法测定水中痕量NO_2~－和NO_3~－

研究了催化光度法测定水中亚硝酸盐氮和硝酸盐氮。在一定条件下，亚硝酸根可以催化甲基红与溴酸钾反应，使甲基红溶液颜色消退，ｌｇ（Ａ０／Ａ）与量成正比，据此测定。硝酸盐用海绵状钢还原后测定总量，差减法求出。     

离子色谱法同时测定硝酸盐和亚硝酸盐分析方法的建立

主要分析了离子色谱法测定环境中的硝酸盐以及亚硝酸盐分析处理方式。基于色谱条件要求,进行硝酸盐以及亚硝酸盐峰的完全分离处理。在同时测定状态中应用于硝酸盐以及亚硝酸盐的测定效果显著、精准度高、具有良好的重复性,简单便捷、灵敏度高的优势特征,在水与蔬菜中的定性定量测定中效果显著。     

人工土层降解废水中氨氮的试验研究

氮在水体中过多地存在,会成为对人类有危害作用的污染因子。就土壤渗滤法去除硝酸铵水溶液中的氨氮、硝酸盐的效能与机理方面进行了初步探讨。人工土层下部填加活性炭不需要驯化过程,便可有效地降解氨氮、硝酸盐氮。下部填加豆石的土壤渗滤柱须经过驯化,才能有效地降解氨氮,但不能去除硝酸盐氮。下部填加活性炭与下部填加豆石的土壤渗滤柱,经过22d的驯化过程之后,亚硝酸盐氮均可降至0.1mg/L以下。     

浅析水体中硝酸盐氮处理的现状及存在的问题

在自然和人为因素影响下,水体中硝酸盐氮污染正日益加剧。人体中摄入过量的硝酸盐氮对健康有严重危害,因此水体中硝酸盐氮污染已成为全球性的环境问题。本文综述了水体中硝酸盐氮去除方法的研究现状,并讨论了新型硝酸盐氮去除方法的应用前景和发展趋势。     

氮素基质类型对同步厌氧生物脱氮除硫工艺性能的影响

采用上流式厌氧污泥床(UASB)反应器研究了同步厌氧生物脱氮除硫工艺对不同基质的耐受性、亲和性和高效性。硝酸盐型脱氮除硫反应所能耐受的最大进水硝酸盐和硫化物浓度分别为189.7mg·L-1和1000mg·L-1,最大硝酸盐和硫化物去除速率分别为0.61kg·m-3·d-1、4.57kg·m-3d-1;亚硝酸盐型脱氮除硫反应所能耐受的最大进水亚硝酸盐和硫化物浓度分别为252.7mg·L-1和880mg·L-1,最大亚硝酸盐和硫化物去除速率分别为0.65kg·m-3·d-1、3.97kg·m-3·d-1。以灵敏度比作为判据,活性污泥对硫化物的耐受性较好,受基质类型的影响不显著;对硝酸盐/亚硝酸盐的耐受性较差,其中对亚硝酸盐的耐受性更差。在硝酸盐型脱氮除硫反应中,硝酸盐和硫化物的半饱和常数分别为(0.35±0.09)mg·L-1、(1.36±0.36)mg·L-1;在亚硝酸盐型脱氮除硫反应中,亚硝酸盐和硫化物的半饱和常数分别为(0.26±0.08)mg·L-1、(1.80±0.30)mg·L-1。硝酸盐型脱氮除硫反应所需的最短反应时间(5h)长于亚硝酸盐型脱氮除硫反应所需的最短反应时间(4h)。     

ITO刻蚀废液中NO3-的还原方法探讨

对N03-的还原做了初步探讨,结果表明铜和过氧化氢可以对其还原,其中用过氧化氢作还原剂生成产物是水,对环境友好无污染。硝酸根离子的浓度采用紫外可见分光光度法测定,实验表明该方法快速简便、准确度高、精密度好。     

硝酸根、亚硝酸根同时存在下的硝酸根含量测定

本文研究了硝酸根、亚硝酸根同时存在下，硝酸根含量的并讨论了加入不同量的亚硝酸根对测定硝酸根的影响．结果表明：此方法测定硝酸根含量是一种即简单又快速的方法．     

FTIR study of aqueous nitrate reduction over Pd/TiO2

The interactions between Pd/TiO₂ catalyst and the reactants and potential reaction intermediates present during aqueous nitrate reduction, including NO₃⁻, NO₂⁻ and NO in the presence of H₂ and H₂O were studied by infrared spectroscopy. Adsorbed forms of NO, nitrite and nitrate could all be detected in the presence of water. In the presence of water/H₂, nitrate was the most stable surface species followed by nitrite and then highly reactive NO, suggesting that the reduction of nitrate to nitrite is the rate-limiting step. High concentrations of adsorbed nitrite appear to be linked to the detection of gaseous N₂O while the formation of ammonia is related to reactions on the Pd surface and the extent of formation is linked to high levels of adsorbed NO in addition to the surface hydrogen availability and the presence of water.     

离子色谱法和分光光度法测定井水中硝酸盐氮和亚硝酸盐氮的对比

文中对比研究了离子色谱法和光度法测定农村井水中硝酸盐氮和亚硝酸盐氮。离子色谱法和光度法测定硝酸盐氮的检出限、精密度、加标回收率分别为0.014 mg/L、1.4%~4.9%、94%~106%和0.030 mg/L、1.6%~6.7%、98%~105%;离子色谱法和光度法测定亚硝酸盐氮的检出限、精密度、加标回收率分别为0.002 mg/L、1.4%~4.4%、90%~102%和0.004 mg/L、0.7%~3.6%、92%~104%。试验结果表明,离子色谱法的检出限低,而两种方法的精密度、准确度、t值检验无显著性差异,两种方法均满足日常监测要求。离子色谱法具有样品前处理过程简单,测定过程快速且可实现多种离子同时检测等优点,更利于对井水水质的检测分析。     

偏最小二乘-神经网络光度法同时测定水中的NO3-和NO2-

应用偏最小二乘-神经网络直接解析硝酸根和亚硝酸根的紫外光谱,不经分离紫外吸光光度法同时测定硝酸根和亚硝酸根。在BP算法上,引用改进的误差传递函数,并采用均匀试验设计法确定了最佳网络运行参数。用于水样中硝酸根和亚硝酸根的同时测定,回收率分别为99.0%,105.0%。     

Nitrate and Nitrite Removal Using a Continuous Heterotrophic Denitrifying Granular Sludge Bioreactor

The denitrification potential of a continuous denitrifying granular‐sludge bioreactor for concentrated nitrate/nitrite wastes was investigated. Granules were cultivated using nitrite as sole electron acceptor. Complete denitrification could be achieved at nitrite, nitrate, and nitrate‐nitrite mixture (50:50) loading rates up to 2.7, 3 and 3 g N L^–1d^–1, respectively. The maximum nitrite and nitrate reduction capacities were limited by the biomass concentration. Removal of nitrate and nitrite was studied with constant biomass concentration at different pH values. A lower pH value resulted in a considerable increase of inhibitory effects of both nitrite and nitrate whereby nitrate exhibited the more significant impact.     

SBR法处理垃圾渗滤液的反硝化过程中NO~-_2积累的研究

The nitrite accumulation in the denitrification process is investigated with sequencing batch reactor (SBR) treating pre-treated landfill leachate in anoxic/anaerobic up-flow anaerobic sludge bed (UASB). Nitrite accumulates obviously at different initial nitrate concentrations (64.9,54.8,49.3 and 29.5 mg&#8226;L－1) and low temperatures, and the two break points on the oxidation-reduction potential (ORP) profile indicate the completion of nitrate and nitrite reduction. Usually, the nitrate reduction rate is used as the sole parameter to characterize the denitrification rate, and nitrite is not even measured. For accuracy, the total oxidized nitrogen (nitrate + nitrite) is used as a measure, though details characterizing the process may be overlooked. Additionally, batch tests are conducted to investigate the effects of C/N ratios and types of carbon sources on the nitrite accumulation during the denitrification. It is observed that carbon source is sufficient for the reduction of nitrate to nitrite, but for further reduction of nitrite to nitrogen gas, is deficient when C/N is below the theoretical critical level of 3.75 based on the stoichiometry of denitrification. Five carbon sources used in this work, except for glucose, may cause the nitrite accumulation. From experimental results and cited literature, it is concluded that Alcaligene species may be contained in the SBR activated-sludge system.     

Kinetic Studies of the Electrochemical Treatment of Nitrate and Nitrite Ions on Iridium‐Modified Carbon Fiber Electrodes

Electrochemical reductions of nitrate and nitrite ions in neutral solution were studied using an Ir‐deposited carbon fiber electrode. The objective of the study was to set up a process to remove nitrate and nitrite ions from industrial and municipal wastes as well as from the nitrate and nitrite ion enriched water supplies. Since nitrate and nitrite ion reduction kinetics is very slow on plain carbon, the iridium‐modified fibers showed a significant reduction of nitrate and nitrite ions. Nitrogen and ammonia were identified as the two major gaseous products of the reduction process. A first‐order inhibition kinetics model is proposed and was used to analyze the nitrate and nitrite ion reduction kinetics. The reduction rates of nitrate and nitrite ions were favored at higher cathode potential (cf. –950 mV and –850 mV) in a solution of pH = 7.0 with hydrogen evolution efficiency increasing with cathodic potential. A simple model for the batch re‐circulation process was developed for the reduction of nitrate ion at surface‐modified fiber electrode. There was a good agreement between the model predictions and experimental results.     

蔬菜水果中硝酸盐与亚硝酸盐的测定及其储藏过程中的含量变化

文章采用离子色谱法/电导检测器,测定了蔬菜水果样品中的硝酸盐和亚硝酸的含量。实验选取并优化样品前处理方法,获得无色透明的溶液后,经0.45μm过滤器过滤后得到待测液,最后自动进样,离子色谱法进行样品测定,以10 mmol/L KOH溶液为淋洗液,相对标准偏差：NO3-为0.38%,NO2-为0.54%;回收率：NO3-为98.8%～99.7%,NO2-为98.6%～99.9%。本方法操作简便快速,且具有仪器稳定性好、测定结果准确可靠的特点。在被测定蔬菜水果中,硝酸盐和亚硝酸盐含量都在较低浓度水平,NO3-：16.8～21.9 mg/kg,NO2-：0.0887～0.164 mg/kg。最后讨论了几种蔬菜水果样品储藏过程中硝酸盐与亚硝酸盐的含量变化情况。     

用微波消解法测定日用化学品中砷时存在的问题及克服方法

针对现有文献方法中微波消解法测定砷时赶酸时间不确定、赶酸不完全等缺点,研究了尿素结合沸水浴加热消除微波消解液中亚硝酸根和挥发性氮氧化物的干扰,考察了微波消解液中剩余硝酸对测定的干扰情况.优化了微波消解-氢化物发生原子吸收法测定日用化学品中砷的条件.方法检出限为0.4 μg/L,定量下限为1.5 μg/L;样品加标测定的相对标准偏差为1.2％,回收率为91％～102％.