连续流动分析仪法测定水中总氰化物

采用连续流动分析仪测定水中总氰化物。通过各类实际样品和标准样品的分析 ,该方法的检出限为0 0 0 2mg L ,相对标准偏差为 0 7%～ 3 0 % ,加标回收率为 96 0 %～ 10 6 0 %。实验表明 ,该方法具有灵敏度、准确度高 ,精密度和回收率好 ,节省试样、试剂等特点 ,并提高了操作的安全性、方便性及工作效率。适用于水质中总氰化物的测定。     

紫外差分分析仪在烟气超低排放监测中的应用

随着节能减排政策的深入实施,关于烟气排放的标准也越来越严格,在超低排放的工程改造中,需要加大对固定污染烟气排放的实时监测,才能达到相应的规范和排放标准,因此紫外差分分析仪在烟气超低排放监测中得到了推广和应用,本文就烟气监测采样技术和分析方法进行分析,针对紫外差分分析仪的各项指标,通过实验室检测结果和最新国家标准之间的对比,对其超低排监测中的应用进行探讨。     

Crosslinking acrylamide with EDTA-intercalated layered double hydroxide for enhanced recovery of Cr(VI) and Congo red: Adsorptive and mechanistic study

• Functional groups of AM and EDTA in composite increased removal of Cr(VI) and CR. • Removal process reached equilibrium within 30 min and was minimally affected by pH. • Elimination of Cr(VI) was promoted by coexisting CR. • Adsorption process of CR was less influenced by the presence of Cr(VI). • Mechanisms were electrostatic attraction, surface complexation and anion exchange. We prepared ethylenediaminetetraacetic acid (EDTA)-intercalated MgAl-layered double hydroxide (LDH-EDTA), then grafted acrylamide (AM) to the LDH-EDTA by a cross-linking method to yield a LDH-EDTA-AM composite; we then evaluated its adsorptive ability for Congo red (CR) and hexavalent chromium (Cr(VI)) in single and binary adsorption systems. The adsorption process on LDH-EDTA-AM for CR and Cr(VI) achieved equilibrium quickly, and the removal efficiencies were minimally affected by initial pH. The maximum uptake quantities of CR and Cr(VI) on LDH-EDTA-AM were 632.9 and 48.47 mg/g, respectively. In mixed systems, chromate removal was stimulated by the presence of CR, while the adsorption efficiency of CR was almost not influenced by coexisting Cr(VI). The mechanisms involved electrostatic attraction, surface complexation, and anion exchange for the adsorption of both hazardous pollutants. In the Cr(VI) adsorption process, reduction also took place. The removal efficiencies in real contaminated water were all higher than those in the laboratory solutions.     

不同原理分析仪观测大气中氮氧化物对比研究

氮氧化物(NOx)是大气二次光化学污染臭氧的重要前体物,但目前对其总量和分量的测量仍存在着一些难以解决的问题。选择3种不同原理的市售氮氧化物分析仪在广东和北京进行比对观测实验,从而比较其各自的优缺点及适用性。结果表明,钼转化法(MC)测得的NOx比光转化法(LC)及液相化学发光法(LPC)所测得的值都明显偏高,可近似认为是NOy。LPC检测NO2时受到PAN等含有—NO2生色基团的干扰,结果比LC略高。LC测得的NOx值与实际大气最为接近。MC测定的NOx比实际值高,但能满足空气质量指标监测的需求;LC能够准确测定大气中的NOx,但造价太高,仅适用于大气化学机理研究;而LPC原理的仪器适合于短时间的航测、高塔和系留艇进行垂直梯度观测。     

阳极溶出伏安法快速测定地表水中镉

利用阳极溶出伏安法原理,采用PDV 6000型重金属快速分析仪测定地表水中的镉。在1.25μg/L~40.0μg/L范围内,质量浓度与阳极溶出峰电流和峰面积呈良好的线性关系,方法检出限为0.001 mg/L,水样平行测定的RSD为8.9%,加标回收率为80.5%~118%,与石墨炉原子吸收光谱法的测定结果基本一致。     

使用毛细管离子分析仪对水中有机、无机阴离子的同时测定

研究在使用毛细管离子分析仪测定水中有机阴离子和无机阴离子的过程中 ,电压、电解质溶液的种类、浓度和 p H值以及样品本身浓度对分离效果的影响 .在优化条件下 ,即二元电解质溶液中铬酸钠和邻苯二甲酸氢钾的浓度分别为 3mmol/L和7.5mmol/L,电渗流改性剂 OFM的加入量为每 1 0 0 ml电解质 2 ml.调节测定溶液的 p H为 7.4～ 7.6时 ,可使常见的几种无机阴离子和几种小分子有机酸阴离子同时出峰 ,并且能够获得较好的分离度 .     

尿素添加剂湿法烟气同时脱硫脱氮工艺实验研究(Ⅱ)

对EA和PA两种添加剂,工艺条件变化对NOx脱除率影响有相同的规律：NOx脱除率不受烟气的浓度变化影响;随烟气的氧化度和吸收反应塔有效高度的增加而迅速增加。对吸收反应温度、尿素和添加剂质量分数、吸收塔有效高度进行正交实验得出最佳工艺条件为：吸收反应温度70℃;吸收塔有效高度1．8m;尿素和添加剂质量分数分别为10％和0．01％。在最佳工艺条件作验证实验得出结果与正交实验得出的结果基本符合,此时SO2脱除率为100%,NOx脱除率大于75％。     

大气污染事故中便携气相色谱测定苯胺的方法研究

快速气体分析仪在环境突发事故中起着重要作用,本研究利用ZNOSE快速气体分析仪,对苯胺气体标准样品以及模拟实际大气样品的气体进行分析,探讨了污染事故中苯胺快速测定方法,并对快速气体分析仪在苯胺污染事故中的适用性进行评定。测定结果表明该方法对苯胺气体样品具有高的灵敏度和快速响应,并对检出物具有非选择性和可变检出限。采在事先做好样品标准谱图的情况下,用ZNOSE快速气体分析仪可以在短时间内确定大气环境中的苯胺及其浓度,能满足环境污染实时监测的需求,尤其是处理环境污染事故。     

Application of an aerosol electrical mobility spectrum analyzer: Charged-particle polarity ratio measurement in the Antarctic and Arctic regions

An aerosol electrical mobility spectrum analyzer (AEMSA), developed at Hanyang University, was employed to investigate the particle charge characteristics in the Antarctic and Arctic regions. The particle charge characteristics in these areas were compared with the charging state in Ansan, South Korea, located in the midlatitude, where artificial factors, such as human activity, urbanization, and traffic, might result in a higher total concentration. Furthermore, in Ansan, South Korea, the charged-particle polarity ratio was very stable and was close to 1. However, notably different particle charge characteristics were obtained in the Antarctic and Arctic regions. The imbalance between the numbers of positively and negatively charged particles was evident, resulting in more positive charges on the atmospheric particles. On average, the positively charged particle concentrations in the Antarctic and Arctic areas were 1.4 and 2.8 times higher, respectively, compared with the negatively charged particles. The developed AEMSA system and the findings of this study provide useful information on the characteristics of atmospheric aerosols in the Antarctic and Arctic regions and can be further utilized to study particle formation mechanisms.     

A novel online analyzer for accurate and rapid measurement of volatile fatty acids in anaerobic wastewater treatment

Volatile fatty acids (VFAs), which are largely generated during the anaerobic acidification process, are considered to be reliable indicators of the stable process operation. However, the common methods for monitoring VFAs are offline, and they are typically manual requiring time-consuming, costly and complex instruments. This study aims to develop a novel online analyzer for automatic measuring VFAs, which was based on the 5-pH point titration, embedded with a proportional-integral-derivative (PID) feedback control system. The results show that it can achieve accurate and rapid monitoring of VFAs ranging between 0-400 mg/L (<9 min/sample) but simultaneously faces the problems of overtitration and interference of complex characteristics of wastewater. In order to improve its accuracy and stability, the effects of three general coefficients (K_I, K_P, and K_D) of PID on the titration were investigated, and the optimal values of K_I, K_P, and K_D were found to be 1.5, 1.0, and -1.0~0.5, respectively. Besides, the initial titration speed was set at 0.06 mL/min, equal to the minimum speed of the peristaltic pump, and the dichotomy approach was integrated into the PID feedback controller. Owing to the above improvements, the relative mean deviation and standard deviation of measuring VFAs in both synthetic and real wastewaters were mostly lower than 5.0% and 5.0 mg/L, proving the online analyzer is rapid, accurate and reliable.