光催化氧化法测定地表水化学需氧量的研究

用溶胶-凝胶法在石英管上制备了纳米TiO₂膜, 并采用光催化氧化法建立了一种测定地表水化学需氧量(COD)的新方法. 以Ce(IV)作为纳米TiO₂光生电子的接受体, 从而减少了纳米TiO₂光生电子和光生空穴的复合, 提高纳米TiO₂的光催化氧化能力. 以测定Ce(IV)的紫外吸收为手段探讨了光催化氧化测定COD的机理, 考察了测定COD的最佳反应条件. 实验结果表明, 该方法条件温和, 不会造成二次污染, 能够实现地表水等低COD值水样的快速准确测定. 在该实验所选择的条件下, 可准确地测定1.0～12 mg?L^－1之间的COD值, 检测限为0.4 mg?L^－1.     

不同电极材料和不同酸介质对3-甲基吡啶电氧化的影响

在以质子交换膜为隔膜的电解池内,通过3-甲基吡啶在PbO₂/Ti、SnO₂/Ti、石墨和MnO₂/Ti电极上的电氧化研究发现,在硫酸溶液中,PbO₂电极是催化活性最高的工作电极.通过3-甲基吡啶在硫酸、高氯酸、磷酸和乙酸介质中的电氧化研究发现,对于PbO₂电极,硫酸是最适合的介质.利用循环伏安实验和恒电位电解实验,研究了电氧化条件和电催化活性,比较了各种条件下的电流效率和选择性.     

钕掺杂二氧化铅复合阳极的电化学性能研究

利用电沉积法制备了钕（Nd）掺杂钛（Ti）基二氧化铅（PbO₂）复合阳极,采用扫描电子显微镜（SEM）、X 射线衍射（XRD）、电化学阻抗谱、线性扫描伏安法、循环伏安法等对所制备电极的表面形貌、物相组成及电化学性能进行了分析. 结果表明,Nd 掺杂使得 PbO₂ 阳极表面颗粒变小、结构更加致密,增大了电极比表面积,改善了电极电化学性能. PbO₂ 和 PbO₂-Nd 阳极表层主要为β- PbO₂,Nd 掺杂提高了β- PbO₂ 的结晶纯度,改变了表面相的相对丰度,促进了β(101)晶面形成. PbO₂-Nd 阳极具有更小的电化学反应电阻,更高的析氧电位,更强的电子交换能力和更长的使用寿命. 将所制备电极应用于处理苯酚模拟难降解有机废水,PbO₂-Nd 阳极对苯酚具有更好的电催化氧化效果,降解3 h,苯酚去除率达85.7%,COD 去除率达73.8%. 循环使用6 次,PbO₂-Nd 阳极电催化活性无明显衰减,显示出更好的电催化耐久性.     

纳米二氧化钛膜光催化分解-电化学法联用测定水体中的总磷

利用电化学方法制备了磷钼酸修饰电极,该修饰电极对溶液中的PO43-有很好的电流响应,继而提出了一种用纳米TiO2-K2S2O7共存体系光催化氧化有机磷生成正磷,然后以磷钼酸修饰电极进行测定的新方法。实验中以有机膦酸为标准物质,研究了测定机理,优化了测定条件。实验表明,本方法操作简单、快速、准确。PO43-在0.04~16 mg/L浓度范围内,与修饰电极上的电流响应呈线性关系,检出限为0.02 mg/L。用本方法测定实际水样与标准分析方法所得结果相近。     

一种新的光催化氧化体系用于化学需氧量的测定研究

基于KMnO₄能获得光生电子从而提高半导体光催化氧化能力的原理,建立了一种用纳米ZnO-KMnO₄协同体系光催化测定化学需氧量(COD)的新方法,探讨了催化氧化测定COD的机理,考察了测定COD的最佳反应条件.COD值浓度在1.5～10mg/L范围内与信号呈良好的线性关系,检测限为0.5mg/L.用本方法测定实际水样,结果和标准高锰酸盐指数法(COD_Mn法)相符.     

Pr-PVP掺杂Ti/PbO2电极制备及其在有机物降解中的应用

在Ti基体上,采用电沉积法制备了镨和聚乙烯吡咯烷酮(PVP)掺杂的Ti/SnO₂-Sb₂O₃/Pr₂O₃-PVP-PbO₂ 电极. SEM显示Ti/SnO₂-Sb₂O₃/Pr₂O₃-PVP-PbO₂ 电极表面颗粒细化,镀层结构更加致密和均匀,XRD 测试表明掺杂使可以使电极的表面颗粒变小.循环伏安 (CV)分析表明共掺杂改性后的电极电催化活性明显提高.强化寿命测试显示Ti/SnO₂-Sb₂O₃/Pr₂O₃-PVP-PbO₂ 电极稳定性更好,使用寿命更长. 将所制备的电极应用于亚甲基蓝(MB)模拟染料废水的降解测试,与常规的Ti/PbO₂ 电极相比,Ti/SnO₂-Sb₂O₃/Pr₂O₃-PVP-PbO₂ 电极对亚甲基蓝具有更好的脱色率和 COD 除去率. 降解120min 后,对30 mg·L ^-1 亚甲基蓝的去除率分别可达到99%,对COD去除率为87.9%.     

TiO2光催化剂在COD测定中的应用研究

采用溶胶一凝胶法制备纳米TiO2薄膜电极,提出了一种简便、快速测量化学需氧量(COD)的方法.分别以葡萄糖、邻苯二甲酸氢钾(KHP)为COD检测的标准物,考察了TiO2薄膜的光催化行为,并与传统方法进行比较.实验结果表明,葡萄糖对紫外光几乎没有吸收,在葡萄糖的电解质溶液中,COD与光电流有很好的一元二次关系;KHP对紫外光有吸收,在KHP的电解质溶液中,当COD浓度大于50mg/L时,随着COD浓度的增加,光电流降低.引入了单位光强度引起的电流响应(E)这一变量,该传感器的单位光强度引起的电流响应E与COD值在15.0-300mg/L范围内有很好的一元二次关系,相关系数为0.9999,并且不同样品在薄膜电极上的E呈现很好的线性关系.该传感器对水样的测量结果与传统方法测量结果相吻合.     

ZrO2掺杂铌基二氧化铅电极制备及其甲基橙降解电催化性能

本文利用电沉积制得ZrO₂掺杂铌基二氧化铅电极,通过扫描电镜（SEM）和X射线衍射（XRD）观察表征了Nb/ZrO₂+PbO₂电极表面形貌特征及组成. 用线性伏安曲线、电化学交流阻抗和循环伏安曲线测试了Nb/ZrO₂+PbO₂电极电化学性能,及其甲基橙（MO）的降解电催化效果. 结果表明,ZrO₂掺杂使Nb/PbO₂电极表面更致密、粗糙,结晶尺寸更小,增大了电极比表面积,提高了电极电催化活性. Nb/ZrO₂+PbO₂电极活性层主要由β-PbO₂和少量的α-PbO₂以及部分ZrO₂共沉积而成. 有较高的析氧电位、吸附电容和较低的电荷转移电阻,其甲基橙（MO）降解电催化活性更佳,降解过程受扩散控制.     

氧化镍/碳纤维电化学传感器制备及用于恩诺沙星的检测

建立了基于镍修饰的碳纤维电化学传感器快速检测恩诺沙星的方法。将碳纤维（CNF）滴涂于玻碳电极（GCE）表面,采用循环伏安法（CV）将NiO纳米粒子沉积于CNF表面,制得NiO/CNF/GCE修饰电极,采用扫描电镜（SEM）和能谱仪（EDS）对修饰材料的形貌和元素进行表征,并将不同修饰电极放在磷酸缓冲液（PBS）中进行CV表征。对传感器制备和测定过程中的影响因素、CNF的滴涂量、缓冲液pH和Ni（NO₃）₂的电聚合圈数进行优化。采用差分脉冲伏安法（DPV）考察该电化学传感器对恩诺沙星的电化学行为。结果表明,制备的NiO/CNF/GCE电化学传感器在CNF滴涂用量为8μL,基质PBS溶液pH 6.0,Ni（NO₃）₂电聚合圈数为12圈时电极灵敏度最高,对恩诺沙星有较高的电化学响应,在0.5～80μmol/L浓度范围内与电流的变化值呈良好的线性关系,线性方程为I_p=0.0729c+0.4015（R²=0.995）,方法检出限为0.17μmol/L,实际样品平均回...     

温度对PbO2电沉积形核生长过程的影响研究

为了探讨温度对PbO₂电沉积形核生长过程的影响,在25℃、35℃、45℃、55℃、65℃使用电化学工作站测试了PbO₂在玻碳电极上沉积过程的循环伏安曲线、计时电位曲线及计时电流曲线,并对不同温度下电沉积的PbO₂镀层进行了SEM和XRD分析. 结果表明,在不同温度下PbO₂都经历了成核和核生长过程. 温度的升高没有改变PbO₂电沉积三维连续成核的模式,降低了沉积过程溶液阻力,对成核和晶体生长速率均有促进作用,在晶核密度达到饱和晶核密度以前,是以促进成核速率为主,减小PbO₂颗粒尺寸. 达到饱和晶核密度后,电沉积后期以促进晶体生长速率为主,不利于形成细小PbO₂颗粒.高温使得析氧速率提高,能耗增大.由实验结果得出,在55℃时得到的PbO₂镀层粒径最小.     

Rapid, sensitive and on-line measurement of chemical oxygen demand by novel optical method based on UV photolysis and chemiluminescence

A novel on-line method based on the combination of UV photolysis and chemiluminescence detection was established and experimentally validated for the determination of chemical oxygen demand (COD). A quantitative amount of free radicals can be produced by analytes in the UV irradiation process. By utilizing the phenomenon that luminol can be oxidized by the free radicals to produce luminescence, COD was successfully determined indirectly. This new approach overcomes many problems associated with the conventional COD determination techniques such as long analysis time, tedious operations, consumption of expressive and toxic reagents, production of secondary toxic waste and poor reproducibility. The method was successfully applied to the determination of COD in synthetic samples, certified reference samples and real samples of river water and lake water. A limit of detection of 0.08 mg/L COD with a linear dynamic range of 0.2-20 mg/L was achieved under the optimum experimental conditions. The proposed method is a unique method that is environmentally friendly (without using any strong oxidizing reagent and any catalysts such as titanium dioxide), rapid (with only 5-10 min required for each sample), sensitive (with the lowest limit of detection for COD so far), simple (mainly with a photo-reactor and a chemiluminescence detector) and automated (using an intermittent flow system).     

Optimization of conditions for the determination of the organic matter content of waters by reagentless oxithermography and its application to the analysis of natural waters

To determine the chemical oxygen demand (COD) of water by oxithermography, we studied a high-temperature reactor with two inputs of the gas flow. Such a design allowed the creation of an internal circuit of the oxygen–inert gas (argon) binary flow in the reactor for the oxidation of organic substances and the determination of COD by the decrease in the concentration of oxygen in the binary mixture. The optimum operation parameters of the instrument, affecting the analytical characteristics of the method, were determined. The detection limit for a water sample of the volume 10 µL was 3.4 mg O/L. It was shown that the oxithermograph and the proposed procedure can be used for the determination of COD in drinking and natural waters of Bryansk oblast. The approach developed has an advantage, consisting in the reagentless rapid determination of the COD of waters without preliminary sample preparation.     

二氧化钛纳米管阵列光电催化测定地表水化学需氧量

利用TiO2纳米管阵列(TNAs)TNAs和薄层反应器(TCR)体积小、传质快、反应时间短的特点,建立了光电催化测定地表水化学需氧量(COD)的新方法.本方法对于地表水COD值的测定呈线性关系,线性回归方程为Qnet=-0.18105ThCOD+0.15444,r=0.9903,检出限为0.30 mg/L;RSD<5%;分析时间<2 min,适宜pH范围是4～10,Cl-不干扰.通过地表水实际水样分析表明,本方法能够克服重铬酸钾法(CODCr)和高锰酸钾指数法(CODMn)的缺陷,测定结果可靠,稳定,重现性好,能够准确、快速地测定地表水的COD含量,是一种极值得推广应用的测定COD的新方法.     

无汞分光光度法快速测定含氯废水化学需氧量

建立无汞分光光度法快速测定含氯废水的化学需氧量。氯离子在测定化学需氧量反应中会增大重铬酸钾的消耗量,进而影响测定的准确性。传统的化学需氧量测定需要使用硫酸汞掩蔽氯化物。通过添加过量硫酸银以减少汞的使用,建立化学需氧量的无汞测定法。研究表明添加硫酸银含量1.03%的Ag2SO4-H2SO4试剂可以掩蔽500 mg/L及以下浓度氯离子的干扰。运用传统的测定方法和无汞测定法对理论化学需氧量为100 mg/L的邻苯二甲酸氢钾溶液进行测定,无汞测定法测定值略高于传统方法测定值。在氯离子浓度低于500 mg/L时,无汞方法测定值的准确度优于传统方法。另外,化学需氧量无汞测定法将化学药品的单位样本使用成本从0.61元降至0.47元。无汞分光光度法适用于含氯废水化学需氧量的快速测定。     

Covalent modification of glassy carbon electrode with aspartic acid for simultaneous determination of hydroquinone and catechol

Glassy carbon electrode (GCE) is covalently modified with aspartic acid (Asp). The modified electrode is used for the simultaneous electrochemical determination of hydroquinone (HQ) and catechol (CC) and shows an excellent electrocatalytical effect on the oxidation of HQ and CC by cyclic voltammetry (CV) in 0.1 mol/L acetate buffer solution (pH 4.5). In differential pulse voltammetric (DPV) measurements, the modified electrode could separate the oxidation peak potentials of HQ and CC present in binary mixtures by about 101 mV though the bare electrode gave a single broad response. A successful elimination of the fouling effect by the oxidized product of HQ on the response of CC has been achieved at the modified electrode. The determination limit of HQ in the presence of 0.1 mmol/L CC was 9.0 x 10(-7) mol/L and the determination limit of CC in the presence of 0.1 mmol/L HQ was 5.0 x 10(-7) mol/L. The proposed method has been applied to the simultaneous determination of HQ and CC in a water sample with simplicity and high selectivity.     

高效阴离子色谱法测定保健食品中的盐酸氨基葡萄糖

建立了保健食品中盐酸氨基葡萄糖的高效阴离子色谱测定方法。在AminoPac PA10离子色谱分离柱(2 mm×250 mm)上,以250 mmol/L NaOH溶液作为流动相,利用Au工作电极、pH参比电极的脉冲安培检测器测定了盐酸氨基葡萄糖。方法的线性范围为0.05～10.0 mg/L,检出限为0.012 mg/L,标准品和样品测定的相对标准偏差分别为0.69%和1.38%。用该法测定了保健食品中盐酸氨基葡萄糖,取得了较为满意的结果,加标回收率为96.6%～105.2%,与国家标准方法的测定结果对照,相对偏差为-1.4%～1.0%,表明所建立的方法具有高的灵敏度和精密度,适合于保健食品中盐酸氨基葡萄糖的分析。     

Electrocatalytic Sensor for the Determination of Chemical Oxygen Demand Using a Lead Dioxide Modified Electrode

An amperometric method that makes use of a nano‐PbO₂ modified electrode as an electrocatalytic sensor for the determination of chemical oxygen demand (COD) is described. The sensor signal was observed as a result of the detection of the oxidation current due to electrocatalytic oxidation of organic compounds in the sample solution. This sensor responded linearly to the COD_Cr of standard samples in the range of 5–3 000 ppm and the detection limit was 2.5 ppm. When using the sensor to determine real samples, it displays short analysis time, simplicity and no sample pretreatment. The sensor was stable for over 20 days in real wastewater samples and has successfully been applied to the determination of COD in real wastewater samples.     

亚硝酸根在磷钼镍杂多酸-聚吡咯膜修饰电极上的伏安行为及其含量测定

研究了亚硝酸根(NO