The Phenomenon of Mutual Media in Polypyrrole with Electroactive Ions

The dependence of the differential capacitance of polypyrrole doped with several typical dopants on potential is presented, which shows that the differential capacitance varies with the potential, the doped polypyrroles with electroactive ions give the largest capacitance near their formal potentials, which is attributed to the mutual media for electron transfer between polypyrrole and electroactive dopants. The existence of two conducting phases was observed in the complex capacitance plots. The electroactive anions act as an intra-conducting-phase medium for electron transfer, the electroactive cations act as an inter-conducting phase medium for electron transfer. The mutual media between polypyrrole and redox dopants lead to the increase of the discharging time.     

靛红掺杂聚吡咯膜修饰电极的电荷传输

利用交流阻抗法研究了靛红掺杂聚吡咯膜内的电荷传输，通过非线性最小二乘法拟合，得出了体系的等效电路，并计算出其电荷扩散系数和异相电子传递反应速率常数。实验结果表明，随着膜厚的增加，活性点增多，异相电子传递反应速率常数增大，同时表观扩散系数也增大。     

Regenerable Leptin Immunosensor Based on Protein G Immobilized Au‐Pyrrole Propylic Acid‐Polypyrrole Nanocomposite

A regenerable, labelless electrochemical immunosensor is investigated. In this work, pyrrole (Py) and pyrrole propylic acid (Pa) were co‐electropolymerized in the presence of gold nanoparticles to form a porous, conductive, stable and hydrophilic nanocomposite, followed by the covalent attachment of protein G to capture an antibody as the probe for the immunoassay. The regeneration of the sensor was achieved by rinsing the electrodes with 0.1 M glycine buffer (pH 2.7). The binding and dissociation of the antibody with protein G and optimization of the efficient immobilization were studied by impedance and optical measurements, respectively. The charge transfer resistance obtained from the impedance measurements is used to study the interaction between antibody‐protein G and antibody‐antigen. The immunosensor performance and its regenerability were evaluated by using anti‐leptin IgG as the probe protein to detect leptin in 0.01 M PBS, and its specificity was tested in 1% human serum. The leptin impedimetric immunosensor exhibits a detection dynamic range of 10–100 000 ng/mL with 10 ng/mL detection limit in 0.01 M PBS+1% serum solutions. This work proves the feasibility to make a sensitive, regenerative electrochemical immunosensor, which could be very useful for environmental control and food analysis.     

The Decay of Methylene Blue in Alkaline Solution

The decomposition of methylene blue in aqueous alkaline solution is described. The rate equation is of the form: , where k = 9.0 × 10^-4 mol^- [dm³s^-1 at 20°C and] = 0.5 mol dm^-3.     

Synthesis,structural characterization and reactivity of manganese tungstate nanoparticles in the oxidative degradation of methylene blue

Nanoparticles of manganese tungstate (MnWO₄) were prepared via an impregnation method using Mn(NO₃)₂·4H₂O and WO₃ as a source of Mn and W, respectively. The morphology of the manganese tungstate nanoparticles was studied in detail by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). MnWO₄ nanoparticles showed severe catalytic performances for the degradation of organic dye (methylene blue, MB) in the presence of tert-butyl hydrogen peroxide, TBHP, as the oxidant at room temperature in water.     

复合树脂及其交换动力学

制备了一种新型的离子交换树脂——复合树脂,该树脂对亚甲基兰的交换速度较001×7树脂快,其平衡官能团利用率为001×7树脂的2倍以上。本文对复合树脂的结构特征及其动力学特性进行了分析。     

ADSORPTION OF METHYLENE BLUE FROM AQUEOUS SOLUTION ON ATTAPULGITE

Batch adsorption experiments were carried out for the removal of methylene blue （MB） from aqueous solution using attapulgite as adsorbent. The effects of various parameters such as temperature, contact time, the pH value, and attapulgite dosage on the adsorption performance were investigated. The standard curve and regression equation were established by spectrophotometry. The adsorption experimental results showed that the adsorption equilibrium data were well in accord with Langmuir adsorptive model. The optimal result was acquired under the experimental condition of attapulgite dosage 0.18g, MB concentration 50.0mg/L, pH 10, and adsorption time 20min at room temperature.     

复阻抗法分析聚吡咯材料的湿敏特性

通过延长聚合时间到96 h合成了一种对湿度敏感的聚吡咯材料. 采用红外(IR)光谱, X射线衍射(XRD)和扫描电子显微镜(SEM)的方法对合成的材料进行了表征. 测量了基于该材料的湿敏元件的湿度特性, 并且得到了在20 Hz-100 kHz频率范围内的复阻抗谱图. 基于测量结果讨论了该材料制备的湿敏元件的湿度敏感机制. 通过对复阻抗谱的分析研究了该湿敏元件的工作机理并且分析了参与导电的粒子.     

Impedimetric Aptasensors Based on Carbon Nanotubes – Poly(methylene blue) Composite

The effect of aptamer structure and immobilization platform on the efficiency of thrombin binding and its detection using electrochemical impedance spectroscopy (EIS) characteristics was investigated with aptasensors based on glassy carbon electrodes covered with multiwalled carbon nanotubes (MWNTs). Aptamers with one or two binding sequences GGTTGGTGTGGTTGG specific for thrombin and poly(dA) and poly(dT) tags able to form dimeric products (aptabodies) were used to establish significance of steric and electrostatic factors in aptasensor performance. We have shown that electropolymerization of methylene blue onto MWNTs significantly improved electrochemical characteristics and sensitivity of thrombin detection against bare MWNTs. Charge transfer resistance and capacitance of the surface layer were measured in the presence of redox probe [Fe(CN)₆]^3?/4?. Aptasensors make it possible to detect thrombin in the concentration range 1 nM–1 µM with the limit of detection of 0.7 nM (monitoring resistance changes) and 0.5 nM (capacitance changes), respectively.     

亚甲基蓝光度法测苯唑西林

在pH8.6～9.8的条件下,亚甲基蓝与苯唑西林反应生成蓝色离子缔合物。体系的最大吸收波长位于606nm,线性范围为0～4.0mg/L,表观摩尔吸光系数为2.60×104L·mol-1.cm-1,探讨了适宜的反应条件、方法的精密度及可靠性。方法已用于药物中阿莫西林的测定。     

累托石对亚甲基蓝吸附性能的研究

研究了累托石对于亚甲基蓝的吸附性能．结果表明，累托石对亚甲基蓝的最大吸附量可迭40．88mg/g，其吸附规律较好的符合Langmuir吸附等温式．累托石能较快的吸附亚甲基蓝，15min即可达到饱和．随着温度的升高，吸附率略有增加，但在常温下累托石也能有效吸附亚甲基蓝．随着pH值的增加，累托石对亚甲基蓝的吸附率增加．已饱和吸附的累托石在400℃高温下煅烧2h后仍能较好的吸附亚甲基蓝．     

溴酚蓝和亚甲蓝双显色体系萃取光度法测定铜

向三元络合物[Cu(phen)_3)BPB的二氯乙烷萃取液中,加入KCN水溶液,形成的[Cu(CN)_2)~-和溴酚蓝离子(BPB)进入水相,向其中加入与BPB颜色相近的亚甲蓝(MB)再进行萃取光度测定。因萃取液中[MB_2BPB)和[Cu(CN)_2)MB两者的吸光作用,使本方法具有很高的灵敏度,ε=1.77×10~5L·mol~(-1)·cm~(-1)。铜含量在0～5μg/25ml遵从比耳定律,对含铜量为10~(-8)g/ml的水样测定5次,相对标准偏差为2％。     

The Photokinetics of Electron Transfer Reaction of Methylene Blue with Titanium Trichloride in Aqueous–Alcoholic Solvents

The kinetics of photoinduced electron transfer reaction of methylene blue (MB) and titanium trichloride was investigated in water and different aqueous–alcoholic solvents. The reaction is pseudo‐first order, dependent only on the concentration of titanium trichloride at a fixed concentration of MB. The effect of water and aqueous–alcoholic solvents was studied in the acidic pH range (4–7). It was observed that the quantum yield (ϕ ) of the reaction increased with increase in polarity of the reaction medium. The quantum yield was high under acidic conditions and decreased with further increase in acidity. The addition of ions and increase in temperature increased the rate and quantum yield of the reaction. The absence of any reaction intermediate was confirmed by spectroscopic investigations. A mechanism for the reaction has been proposed in accordance with the kinetics of the reaction. The activation energy (E _a) was calculated by the Arrhenius relation. Thermodynamic parameters such as E _a, enthalpy change (ΔH ), free energy change (ΔG ), and entropy change (ΔS ) were also evaluated.     

Methylene Blue Poly(Vinyl Chloride) Membrane Electrode Based on the Methylene Blue-Teteraphenylborate Ion-Pair Complex and Its Application to Pharmaceutical Analysis

Abstract

A methylene blue (MB) poly (vinyl chloride) membrane electrode based on MBtetraphenylborate (TPB) ion-pair complex is described. The linear response covers the range 1x10^?2 - 1x10^?6 mol dm^?3 MB solution, with a slope of 56.5±0.5 mv/decade (pH range 3.0-1 0.0). The detection limit is 7.75x 10^?7 mol dm^?3. The electrode shows stability, good reproducibility and fast response. Interferences from common inorganic cations and some organic bases are negligible. These characteristics of the electrode enabled it to be used successfully for the determination of MB in injection.     

Kinetic-spectrophotometric method for the determination of trace amounts of bromide in seawater

A novel simple, sensitive and rapid kinetic-spectrophotometric method is proposed for the determination of trace amounts of bromide. The method is based on its catalytic effect on the oxidation of methylene blue (MB) by hydrogen peroxide in strongly acidic solution. The oxidation reaction is activated by large amounts of chloride and can be monitored spectrophotometrically by measuring the decrease in the absorbance of MB at 746 nm. The determination of bromide is performed by a fixed-time method at the first 100 s from the initiation of the reaction. Unlike other kinetic-spectrophotometric methods for the determination of bromide, the proposed method does not require heating the solution. Bromide can be determined in the range from 80 to 960 μg l⁻¹ with the detection limit of 35 μg l⁻¹. The relative standard deviation of ten replicate determination of 480 μg l⁻¹ bromide was 1.4%. The influence of potential interfering ions was studied. The proposed method was satisfactorily applied to the determination of bromide in seawater without interfering effect from chloride ion.     

Modeling and Thermodynamics of Methylene Blue and Acid Blue 80 Adsorption onto Potato Residue Based Activated Carbon

A study was made on the adsorption kinetics and thermodynamics of methylene blue(MB) and acid blue 80(AB80) onto powder of activated carbon(PAC) prepared by chemical method from dry potato residue(DPR). The PAC was characterized by N₂ adsorption-desorption isotherms analysis and scanning electron microscopy. The ma- ximum adsorption capacities of PAC for MB and AB80 at 303 K are 532.19 and 156.22 mg/g, respectively. The results indicate that the adsorption kinetics of the selected dyes on PAC is well-described by the pseudo-second order model. And their thermodynamic data were analyzed via the isotherms of Langmuir, Freundlich, Redlich-Peterson, Toth and Sips, and the thermodynamic parameters were calculated. The results show that PAC is a fast and effective adsorbent for removing the cationic dyes from aqueous solutions.     

两点电位滴定法测定染料亚甲基蓝的含量

将两点电位滴定法应用于亚甲基蓝等含可电离氯离子的碱性染料的测定。只需在滴定终点前附近记录两次AgNO3标准溶液体积和相应的电极电位值,利用两点法公式计算滴定终点,从而确定亚甲基蓝含量,此法简便、灵敏、准确。     

Activated carbon blended with grape stalks powder: Properties modification and its application in a dye adsorption

In this study, activated carbon was blended with grape stalks powder to adsorb methylene blue (MB) dye with various concentrations from a wastewater. For this purpose, five independent variables involving pH (2–13), contact time (5–270 min), grape stalks powder dosage (0.1–10 g/l), methylene blue initial concentration (20–300 mg/l), and activated carbon dosage (0.1–10 g/l) for methylene blue adsorption were studied. The Central Composite Design (CCD) under Response Surface Methodology (RSM) was applied to estimate the independent variables effects on the methylene blue adsorption. The pseudo- first order, pseudo-second order, Elovich and intraparticle diffusion models were employed to study the adsorption kinetics and isotherm. The Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models were applied to investigate the adsorption isotherm. It was concluded that the intraparticle diffusion isotherm and pseudo-second order kinetic models could show the best results. Furthermore, some data such as physical adsorption (by analyzing FTR and applying some standard equations) and mean free energy (E) were discovered in this research. Finally, activated carbon blended with grape stalks powder as an effective bio-adsorbent for the methylene blue reduction from a wastewater was introduced.     

反胶束笼对纳米氯化银反应性能的微环境限定

研究了反胶束中直径为10～17nm的AgCl微粒与亚甲基蓝之间的作用，比较了阴离子型和非离子型表面活性剂组成的反胶束微环境的影响，讨论了亚甲基蓝在粒子上的吸附，二聚体形成和纳米AgCl粒子对亚甲基蓝荧光猝灭机制．     

反胶束笼对纳米氯化银反应性能的微环境限定

研究了反映束中直径为１０￣１７ｎｍ的ＡｇＣｌ微料与亚甲基蓝之间的作用，比较了阴离子型和非离子型表面活性剂组成的反胶束微环境的影响，讨论了亚甲基蓝在粒子上的吸附，二聚体形成的钠米ＡｇＣｌ粒子对亚甲基蓝荧光猝灭机制。