Studies on the Electrochemical Behavior of Bleomycin at a Co/GC Ion Implantation Modified Electrode and Its Application

In a 0. 10 mol/L HAc-NaAc buffer solution (pH = 4. 59), a sensitive reduction peak of bleomycin was observed by linear sweep voltammetry at a Co/GC ion implantation modified electrode. The peak potential was-0. 73 V(iw. SCE). The peak current was proportional to the concentration of bleomycin over the range of 5.0 × 10-8-1.0× 10-6 and 1.0× 10-6-1. 0 × 10-5 mol/L with a detection limit of 2.0 × 10-8 mol/L. The electrochemical behavior of the reduction peak of bleomycin at the Co/GC modified electrode was studied by linear sweep and cyclic voltammetry and applied to the determination of bleomycin in urine. This method is simple, rapid and reliable. The reduction process is quasi-reversible. The experiments of AES and XPS showed that Co was surely implanted into the surface of GCE and the depth distribution of Co was in good agreement with Gooses normal distribution; the implanted Co at GCE improved the electrocatalytic activity.

Electrochemical behavior of Fe(Ⅲ)in Na_(2)SiO_(3)-SiO_(2)-Fe_(2)O_(3)molten salt

The high-temperature requirement for liquid iron smelting via molten oxide electrolysis presents significant challenges.This study investigates the electrochemical reduction of Fe(Ⅲ)in a novel low-temperature electrolyte,Na_(2)SiO_(3)-SiO_(2)-Fe_(2)O_(3),utilizing cyclic voltammetry and square wave voltammetry techniques.The results show that Fe(Ⅲ)reduction occurs in two steps:Fe(Ⅲ)+e^(−)→Fe(Ⅱ),Fe(Ⅱ)+2e^(−)→Fe,and that the redox process of Fe(Ⅲ)/Fe(Ⅱ)at the tungsten electrode is an irreversible reaction controlled by diffusion.The diffusion coefficients of Fe(Ⅲ)in the molten Na_(2)SiO_(3)-SiO_(2)-Fe_(2)O_(3)in the temperature range of 1248–1278 K are between 1.86×10^(−6)cm^(2)/s and 1.58×10^(−4)cm^(2)/s.The diffusion activation energy of Fe(Ⅲ)in the molten salt is 1825.41 kJ/mol.As confirmed by XRD analysis,potentiostatic electrolysis at−0.857 V(vs.O_(2)/O_(complex)^(2-))for 6 h produces metallic iron on the cathode.

Electrochemical behavior of galena and jamesonite flotation in high alkaline pulp

In order to effectively separate galena and jamesonite and improve the recovery during the mixing flotation, the interaction mechanisms between the minerals and the collector of diethyl dithiocarbamate （DDTC） were investigated. Single mineral flotation test was organized to research the effect of pulp pH value on the flotation behavior of galena and jamesonite. Electrochemistry property of the interaction of these two minerals with DDTC was investigated by cyclic voltammetry and Tafel tests. Flotation test shows that the recovery of jamesonite in high alkaline pulp is strongly depressed by lime （Ca（OH）2）. The cyclic voltammetry and Tafel tests results show that the interaction between galena and DDTC is an electrochemical process. High pH value has little influence on the interaction between galena and DDTC, while it has great effect on jamesonite due to self-oxidation and specific adsorption of OH^- and CaOH^＋ on jamesonite surface. Non-electroactive hydroxyl compound and low-electroconductive calcium compounds cover the surface of jamesonite, which impedes electron transfer and DDTC adsorption, thus leads to very low floatability of jamesonite.

Electrochemical-Voltammetry Behavior of Several Aromatic Aldehydes in Acid Solution

The electrochemical-voltammetry behavior of vanillin, heliotropin, anisaldehyde on the surface of Pt, Au electrodes in acid solution has been studied by means of the electrochemical cyclic voltammetry method. It was found that the electrochemical processes of them are irreversible on both Pt and Au electrodes. The electrochemical activity of vanillin is stronger than heliotropin's and heliotropin's is stronger than anisaldehyde's on Pt electrode. While the electrochemical activity of anisaldehyde is stronger than heliotropin's and vanillin's is the weakest on Au. The results indicate that when they are used as additives for electroplating, they must be consumptive, and it will improve the leveling ability of plating solution and brightness of the deposition layer.

Electrochemical behavior of tantalum in ethylene carbonate and aluminum chloride solvate ionic liquid

To investigate the electrochemical reduction mechanism of Ta(Ⅴ)in ethylene carbonate and aluminum chloride(EC-AlCl3)solvate ionic liquid,cyclic voltammetry experiments were conducted on a tungsten working electrode.Four reduction peaks were observed in the cyclic voltammogram of the EC-AlCl3-TaCl5 ionic liquid.The reduction peaks at-0.55,-0.72,and-1.12 V(vs Al)were related to the reduction of Ta(Ⅴ)to tantalum metal by three stages including the formation of Ta(Ⅳ)and Ta(Ⅲ)complex ions.The reduction of Ta(Ⅲ)to tantalum metal was an irreversible diffusion-controlled reaction with a diffusion coefficient of 3.7×10^-7 cm^2/s at 323 K,and the diffusion activation energy was 77 k J/mol.Moreover,the cathode products at 323 K were characterized by scanning electron microscopy,energy-dispersive spectroscopy,and X-ray photoelectron spectroscopy.The results showed that tantalum metal and tantalum oxides were obtained by potentiostatic electrodeposition at-0.8 V for 2 h.

Electrochemical Behavior of Novel Bis(Aliphatic Amine) Ruthenium(Ⅱ)and Osmium (Ⅱ) Porphyrins

Bis (aliphatic amine ) ruthenium (Ⅱ) and osmium (Ⅱ) porphyrins, M (Por )-(H2NR)2 andM(Por) (HNR'2)2, [M = Ru and Os; Por=meso-tetrakis (p-tolyl)porphyrinato (TTP), meso-tetrakis (4-chlorophenyl )porphyrinato (4-Cl-TPP ), meso-tetrakis (3, 5-dichlorophenyl) porphyrinato (3, 5-Cl-TPP ) andmeso-tetraphenyl porphyrinato(TPP); R=methyl, ethyl, iso-propyl and t-butyl; R'=methyl and ethyl]were synthesized by us. The electrochemical behavior of these complexes in 1,2-dichloroethane with TBABF4as supporting electrolyte, has been studied by cyclic voltammetry and controlled potential electrolysis. Bis(aliphatic amine)ruthenium (Ⅱ)porphyrins under go reversible one-electron oxidation and one-electron reduction processes in 1,2-dichloroethane solution. The osmium(Ⅱ) analogues is shown two oxidation couplesⅢ and Ⅴ, an additional small wave Ⅳ. The redox potentials of these complexes are markedly dependent onthe nature of the substituent bound to the phenyl group of the porphyrin ring. It is obvious that redox potentials increases the electron-withdrawing power of the substituents increases. The couple I was found at-0. 34, -0. 23 and -0. 15 V vs CP2 Fe+/o (Cp2Fe = ferrocene) for Ru (TPP ) (H2NBu-t)2, Ru (4-Cl-TPP)(H2NBu-t)2 and Ru (3, 5-Cl-TPP) (H2NBu-t)2 respectively.

Electrochemical behavior of CoCl_2 in ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate

The electrochemical behavior of CoCl2 in 1-butyl-3-methylimidazolium hexafluorophosphate (bmim]PF6) was investigated by cyclic voltammetry. The cyclic voltammograms were obtained from electrochemical measurement under different temperatures, and the reversible behavior for Co2+/Co3+ redox couple on glassy carbon electrode in bmim]PF6 was confirmed by the characteristic of the peak currents. The diffusion coefficients (about 10-11 m2/s) of Co2+ in bmim]PF6 under different temperatures were evaluated from the dependence of the peak current density on the potential scan rates in cyclic voltammograms. It is found that the diffusion coefficient increases with increasing temperature. Diffusion activation energy of Co2+ in bmim]PF6 is also calculated to be 23.4 kJ/mol according to the relationship between diffusion coefficient and temperature.

和厚朴酚的电化学行为及反应机理研究

和厚朴酚在0．1mol/LNH3－NH4Cl缓冲溶液（pH9．4）中，用线性扫描伏安法得到两个还原峰P1和P2。峰电位分别为Ep1＝－0·23V和Ep2＝-1.18V（vs.Ag／AgCl）。用线性扫描与循环伏安法、脉冲极谱法和恒电位库仑法等手段研究体系的电化学行为及其反应机理。实验表明，P1和P2均为不可逆波。P1和P2的电子转移数均为2。和厚朴酚在汞电极上的吸附具有中性分子吸附的特征，吸附符合Frumkin吸附等温式，吸附系数β＝4．0×105mol/L，吸引因数α＝1．54，饱和吸附量гm=7．4×10-11mol·cm－2。P1的电子转移系数为0．80，非均相电极反应速率常数k1＝3．2×10-4cm／s。通过量化计算，证明P1是分子中酚羟基邻位上的碳碳双键的还原峰，P2是其对位上的碳碳双键的还原峰。

金刚石膜电极对有机污染物的电催化特性

研究了化学气相沉积法 (CVD)制备得到的掺硼金刚石膜电极的物理性质和电化学性能 .用扫描电子显微镜 (SEM )法表征了金刚石膜的表面微观结构 ,采用循环伏安法和交流阻抗法研究了电极的电化学性质 .结果表明 ,金刚石薄膜表面形态为复晶结构 ,颗粒大小均匀 ,掺硼后使电极具有良好的导电性能 .金刚石膜电极具有很宽的电势窗口 ,在酸性、中性和碱性 3种介质中分别为 4 3V、4 0V和 3 0V .同时 ,金刚石膜电极的背景电流非常低 ,为 - 9× 1 0 -6～ 5× 1 0 -7A .在铁氰化钾电解液中 ,金刚石膜电极表面在反应过程中始终保持良好的活性 ,在表面进行的电化学反应具有良好的准可逆性 ,其电极动力学主要是受扩散过程所控制 .金刚石膜电极对有机污染物的催化氧化作用具有选择性 .与铂电极和石墨电极相比 ,金刚石膜电极对苯酚、硝基苯等芳香化合物的催化氧化强烈 ,氧化过程较为简单、彻底 .

乙酰胆碱酯酶催化水解产物的电化学行为

报道了乙酰硫代胆碱水解产物硫代胆碱在玻碳电极上的电化学行为。以乙酰硫代胆碱作底物,在一定条件下乙酰胆碱酯酶催化底物水解,生成电活性物质硫代胆碱。利用循环伏安法和线性扫描伏安法研究了酶催化水解产物硫代胆碱在玻碳电极上的电化学行为。结果表明:在0.1mol/L的B-R缓冲溶液(pH7.0)中,硫代胆碱有一灵敏的氧化峰,峰电位EP=0.32V(vs.SCE);该体系属具有吸附性的不可逆过程。实验测得电子转移数为2,电极反应速率常数k=0.29s-1。

银掺杂改性蒙脱土修饰电极上对苯二酚的电化学行为与测定

利用十八烷基三甲基溴化铵（STAB）和银氨溶液制备了银掺杂改性蒙脱土，并用X射线衍射法、扫描电镜法和交流阻抗法对其进行表征。用循环伏安法（CV）研究了对苯二酚在银掺杂改性蒙脱土修饰电极上的电化学行为，测定了部分动力学参数。结果表明，对苯二酚在电极上的阳极过程受吸附-扩散混合控制，阴极过程受扩散控制，转移的电子数n和质子数m均为2，传递系数α=0．6588，β=0．3412，电极有效面积Aeff=0．0264cm^2，扩散系数D=6．34×10^-5cm^2／s。用方波伏安法（SWV）研究了对苯二酚浓度与峰电流之间的线性关系，在优化实验条件下，对苯二酚浓度在4．0×10^-6-5．0×10^-4mol／L范围内与峰电流呈线性关系，检出限为1．13×10^-7mol／L，用该方法测定了实际水样中对苯二酚的含量，加标回收率为100％～108％。该修饰电极具有良好的重复性与稳定性。

冰醋酸中肾上腺素的现场光谱电化学行为

采用以石墨为工作电极的长光程薄层光谱电化学池, 用循环伏安法、恒电位光谱法和单电位跃计时吸光度法,研究了肾上腺素(AD)在冰醋酸介质中的电子转移反应。结果表明:AD在冰醋酸介质中电氧化反应产物为肾上腺素醌,还原态和氧化态的扩散系数分别为 3. 98×10-6 cm2 /s和 3. 90×10-6 cm2 /s;电极反应的式量电极电位为 0. 632V(vs.SCE),式量异相电子转移速率常数为 7. 30×10-4cm/s;传递系数为 0. 15。

烟酸的电化学行为与测定

用循环伏安法研究了不同支持电解质溶液中烟酸的电化学行为。烟酸在玻碳电极表面有良好的电化学响应信号。在碱性介质中，烟酸被不可逆氧化，氧化产物具有电活性，可发生准可逆氧化还原反应；在酸性介质中，烟酸发生两步准可逆氧化还原反应。结合红外、紫外光谱分析，提出了烟酸在不同酸度的介质中的电化学反应历程。并根据－０．１３Ｖ处的氧化峰电流与烟酸浓度的关系。

核黄素丁酸酯在汞电极上的吸附伏安特性及其反应速率常数的测定

循环伏安法表明，在ＮａＯＨ底液中核黄素丁酸酯（ｒｉｂｏｆｌａｖｉｎｅ ｔｅｔｒａｂｕｔｙｒａｔｅ，ＲＴ）在汞电极上有一对氧化还原峰，其峰电位Ｅｐｃ＝Ｅｐａ＝－０．６４Ｖ（ｖｓ．Ａｇ／ＡｇＣｌ）。本文用多种电化学手段对ＲＴ的吸附特性进行了较详细的研究。吸附粒子为ＲＴ中性分子，测得ＲＴ在汞电极上的饱和吸附量为５．４２×１０－１１ｍｏｌ／ｃｍ２，每个ＲＴ分子所占电极面积为３．０６ｎｍ２，ＲＴ在悬汞电极上的吸附符合Ｆｒｕｍｋｉｎ等温式。测得吸附系数β＝４．６×１０５，吸引因素γ＝ １． １０，吸附自由能△Ｇ°＝－ ３２． ３０ ｋＪ／ｍｏｌ。本文还用循环伏安法研究了ＲＴ的电极反应动力学性质，测定了其在汞电极上的反应速率常数。

百草枯在碳纳米管与离子液体复合修饰电极上的电化学行为及测定

制备了碳纳米管（MWCNTs）和疏水性离子液体1－丁基－3－甲基咪唑六氟磷酸盐（BMIMPF6）复合修饰电极（MWCNTs—BMIMPF6／GCE），并采用红外光谱（IR）分别对MWCNTs、BMIMPF6及MWCNTs—BMIMPF6进行了表征。运用循环伏安法研究了百草枯（PQ）在该修饰电极上的电化学行为。结果表明，在pH7．0的PBS缓冲溶液中，PQ在MWCNTs—BMIMPF6／GCE上出现2对明显的氧化还原峰，在20～200mV／s扫描速率范围内，其氧化还原峰电流均与扫描速率平方根（v^1/2）呈线性关系，表明该电极过程受扩散控制。计算了电极过程的部分动力学参数：电极有效面积A=0．1564cm^2，百草枯在pH7．0的PBS缓冲液中的扩散系数D=7．0×10^-5cm^3／s。优化了方波溶出伏安法（SWSV）的实验参数，发现峰电流Ipal与PQ浓度在7．729×10^-7～9．660×10^-5moL／L范围内呈线性关系，检出限为1．576×10^-7mol／L。采用该方法对实际水样进行检测，增敏回婀率为93％～104％．

微分脉冲溶出伏安法测定食品中的香兰素

报道了食品中香兰素的伏安测定方法。在 pH6 .0磷酸氢二钠 -柠檬酸缓冲溶液中 ,香兰素有一灵敏的氧化峰 ,峰电位为 6 2 0mV(vs .Ag/AgCl)。峰电流与香兰素的浓度在 1.0 - 2 0 .0 μg/mL范围内呈线性关系。检测限为 0 .82 5 8μg/mL。对香兰素的电化学行为进行了较详细的探讨。该法用于食品中香兰素含量的测定 ,结果令人满意。

香兰素在玻碳电极上的电化学行为及其循环伏安测定

在pH7.5的Tris-HCl缓冲介质的底液中,在循环伏安图上在峰电位+0.54V处可见到香兰素的灵敏的氧化峰。其峰电流Ip与香兰素的浓度在3.286×10-6～3.944×10-4mol·L-1范围内呈线性关系,检出限(3S/N)为1.643×10-6mol·L-1。据此提出了循环伏安测定香兰素的方法,并应用于测定巧克力中香兰素的含量。在巧克力试样中加入不同浓度的香兰素标准,按方法测定以求测定方法的回收率,研究了香兰素在玻碳电极上的电化学行为,结果表明:香兰素的电极过程具有吸附性和不可逆性。

铝电极在LiNO3-KNO3熔盐中的电化学行为

采用循环伏安和恒电位电解法考察了铝电极在LiNO3-KNO3熔盐中的电化学行为.实验结果表明,在该熔盐中,锂离子在铝电极上的电还原过程伴随着新生态的锂原子向电极内部的随后扩散步骤;锂原子进入铝电极后与铝发生合金化,形成β-LiAl合金和γ-LiAl合金;锂离子在铝电极上的还原过程受还原态锂在铝基体内的扩散步骤控制.循环伏安实验发现,铝电极在该熔盐中的氧化和还原峰电流都先随循环次数增加而增大,最后基本上趋于稳定.这表明铝电极在该熔盐体系中具有较好的电化学稳定性.

汞膜电极上N-乙酰-L-半胱氨酸的电化学行为

研究了汞膜电极上N 乙酰 L 半胱氨酸 (C5H8O3 SH ,NAC)的电化学行为和测定方法。在 0 .1mol LHAc NaAc缓冲溶液 (pH =4 .5 )介质中 ,方波伏安扫描于～ -0 .2 5V(vs.Ag AgCl)处出现一灵敏的阴极还原峰 ,用循环伏安法、线性扫描极谱法和脉冲极谱法等手段研究了体系的电化学行为及其反应机理。实验表明 :该峰具有明显吸附性 ,吸附分子为Hg2 (C5H8O3 S) 2 ,电子转移系数α为 0 .82 ,电子转移数为 1。NAC的浓度在1 2×1 0 - 8～ 5 .0× 1 0 - 6 mol L范围与其方波伏安峰高有良好的线性关系。方法的检出限为 5 .0× 1 0 - 9mol L ,用于富露施颗粒剂中NAC含量的测定 。

电化学沉积方法对聚苯胺涂层抗腐蚀性能及电化学性能的影响

聚苯胺涂层的电化学特性及耐蚀性与其合成方法及工艺有着密切的关系。在以硫酸为掺杂剂的合成溶液中采用循环伏安和恒电流方法在304不锈钢表面沉积出了聚苯胺涂层。用扫描电镜和电化学方法研究了聚苯胺涂层的表面形貌、抗腐蚀性能和电化学性能。结果表明:聚苯胺涂层表面为多孔结构;开路电位-时间曲线表明,在腐蚀介质中,2种聚苯胺涂层均提高了304不锈钢的腐蚀电位,电化学阻抗谱结果表明,2种聚苯胺涂层在腐蚀初期反应均受扩散步骤控制,对腐蚀介质有一定的阻挡作用,但恒电流方法制备的聚苯胺在浸泡24h后,表现为基体金属的阻抗谱特征。因此,相对于恒电流方法,循环伏安方法制备的聚苯胺对304不锈钢的钝化能力更强,可为基体提供更好的保护。