超声消解FIA-FAAS快速测定环境水样中COD

采用超声消解,流动注射-火焰原子吸收法对环境水样中COD进行了测定。采用酸性KMnO4作氧化剂,在80℃下超声消解,被COD还原生成的Mn^2＋经冷却后在线分离吸附于阳离子交换树脂微型柱上,用3 mol/L HCl反相洗脱,送至火焰原子吸收检测器检测。在消解时间30 s的条件下,测定COD的线性范围为3-300 mg/L,检出限为1 mg/L,采样频率为24 h^-1,Cl^-和Mg^2＋的质量浓度分别至1000 mg/L时均无干扰,对30 mg/L的标准样品重复测定9次,相对标准偏差为2.7%。该法用于河水、池塘水和自来水分析,获得了与经典重铬酸钾法基本一致的测定结果。     

插入式超声化学反应器的设计与仿真研究

超声辅助水样消解技术实现了水质多参数检测的快速性、准确性,而声化学反应器在超声消解法中起到了关键性作用。从理论方面分析了影响超声波在声化学反应器中能量传播的主要因素是反应器结构和几何尺寸;采用ANSYS软件仿真,设计了一种变幅杆插入式声化学反应器。通过MATLAB软件进行声场仿真分析,与槽式相比,插入式具有降低能量损耗,提高传播效率的优势。设计实验证明,基于插入式化学反应器的超声辅助快速检测方法测得标准邻苯二甲酸氢钾(KHP)溶液的化学需氧量(COD)值同国标法测得的COD值非常接近,准确度在-9.2%~4.4%,且测量重复性好,周期较短。该方法更有利于水质在线检测技术。     

The versatility of molecular ruthenium catalyst RuCl(COD)(C5Me5)

This review reports the contribution of the catalyst precursor RuCl(COD)C₅Me₅, and of the Rennes team, for the selective transformation of alkynes to generate high value chemicals with atom economy reactions. Ruthenium activation processes are discussed. Are successively presented (i) the cross-oxidative coupling of alkyne and allyl alcohol to generate γ,δ-unsaturated aldehydes, (ii) the head-to-head dimerisation of alkynes in the presence of carboxylic acids, via a mixed Fischer-Schrock type biscarbene-ruthenium complex, to give functional dienes, and that of propargyl alcohols, via cyclobutadienyl-ruthenium intermediate, to produce cyclobutene derivatives, (iii) the addition of diazoalkanes to alkynes leading to functional dienes via double carbene addition and (iv) the reaction of diazoalkanes to enynes leading to new bicyclo[3.1.0]hexane compounds. Most of the above catalytic reactions involve carbene-ruthenium catalytic species of type Cp*(Cl)Ru(biscarbene) or Cp*(Cl)RuCHR.     

Rhodium-catalysed chemo- and regio-selective [3 + 2+2] cycloadditions of bis(methylenecyclopropanes) and alkynes: Synthesis of spirocyclic 5–7 condensed cycloheptenes

Abstract

Rhodium-catalyzed intermolecular [3?+?2+2] cycloaddition reactions of bis(methylenecyclopropanes) with different alkynes are described. The rhodium-catalyzed [3?+?2+2] cycloadditions resulted in the formation of functionalized 5–7–3 spirocyclic carbocycles in moderate yields with excellent regio- and chemo-selectivity.     

屈服后表面裂纹与穿透裂纹的等效裂纹长度换算

在较小范围屈服条件下，将D-M模型和弹塑性线弹簧模型相结合，建立了屈服后一般扁壳表面裂纹的计算模型，导出了其控制方程和相应的COD计算公式。在此基础上，提出了屈服后一般扁壳表面裂纹与平板穿透裂纹的等COD换算方法。通过各种影响因素的分析并去除次要因素，最终给出了该等效换算关系的简单拟合公式。计算结果表明，该分析方法简便且有足够的工程精度，适应于在役压力容器等结构的现场快速断裂评定。     

Treatment of sugar processing industry wastewater using copper electrode by electrocoagulation: Performance and economic study

This paper demonstrates the use of copper electrode for the treatment of sugar processing industry wastewater (SPIW) in terms of chemical oxygen demand (COD) by applying electrocoagulation (EC) method. EC process was carried out in batch mode with electrode effective area of 0.0112 m², supplied current intensity (CI) of 44.64 A/m² - 223.21 A/m², electrode gap (EG) of 0.5–2.5 cm, electrolyte (NaCl) dose (ED) of 0.5–2.5 g/L to treat SPIW with initial chemical oxygen demand (COD) of 6000 mg/L. The maximum COD removal 73% of SPIW is achieved at optimized condition of SPIW pH: 7, CI: 89.28 A/m², EG: 1.5 cm & ED: 1.5 g/L. Sludge and scum generated during EC process were characterized by FTIR, TGA/DTA/DTG, proximate & ultimate analysis to find its applicability and their disposal. Additionally, economic study of EC treatment process at optimum condition suggest treatment cost was 11.2 US$/m³ and it indicate economic results as comparison to other available treatment processes.     

基于超声-ORP原理的快速COD检测法研究

针对传统水质化学需氧量(COD)在线检测方法检测稳定性差、易受环境影响等缺陷,为提高水质COD在线检测效率和稳定性,本文基于超声化学原理和氧化还原电位法(ORP),提出一种在超声波辅助消解(UASD)作用下基于ORP法的COD检测方法：UASD-ORP法。通过超声波辐照下空化气泡微射流的加强传质、表面自由基活化等特效作用消解待测水样,结合ORP监测溶液的宏观氧化-还原性,保证COD检测中后续滴定过程的准确性、稳定性。实验表明,经该方法检测标准邻苯二甲酸氢钾(KHP)溶液的COD值同国标法测得的COD值非常接近,相对误差在-6.0%~-3.0%之间;对污水样品实地测试中,该方法测得的COD值与标准方法测得的COD值的准确度在-10%~-1.5%之间。应用UASD-ORP法完成COD检测周期在15min~20min,且测量值重复性≤3%。实验验证了该方法具有可行性,可以用于开发在线检测技术。     

Amperometric Determination of Chemical Oxygen Demand via the Functional Combination of Three Digestion Types

The study focused on the proposal and experimental validation of an combined photoelectrocatalytic principle for chemical oxygen demand determination (combined PeCOD, PeCOD‐combined), which was functionally comprised of photon‐efficient thin‐film photochemical, photocarrier‐efficient electrochemical and conventional bulk‐phase photochemical digestion types in one single photodigestion process. The combined PeCOD technology was proposed mainly on the basis of the significantly informative work of existing photoelectrocatalytic COD (thin‐layer PeCOD, PeCOD‐thin), and could realize the three different digestion types on one single rotating photoanode. The three important operation conditions of rotating speed, applied bias and pH value were investigated and optimized, and a wide analytical linear range of 2.7–11 500 mg/L was consequently obtained during an approximately 5–110 min determination period, and a real sample analysis further validated the practical feasibility of the proposed PeCOD‐combined. In PeCOD‐combined the main organics digestion and signal generation occurred via PeCOD‐thin due to efficient UV utilization and excellent photodigestion activity.