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利用吸附的方法在热解石墨电极上制得邻苯二酚紫(PCV)修饰电极.在NH_3·H_2O-NH_4Cl底液(pH8.5)中,该电极具有很好的电化学活性,其示差脉冲氧化峰电位为E_(pa)=+80mV.对铝进行检测,只是峰电流降低,而峰电位不变,氧化峰电流的降低值与铝浓度在1×10~(-8)～1×10~(-7)·dm~(-3)和1×10~(-7)～1×10~(-6)mol.dm~(-3)范围内成正比,检测限为5×10~(-9)mol·dm~(-3),标准偏差为5.0％(4×10~(-8)mol·dm~(-3)Al,n=8),对实际水样进行测定,结果令人满意.对其检测机理进行了研究后认为:(1)PCV修饰电极表面是PCV单分子层吸附,具有很好的电化学活性;(2)铝与PCV在电极表面形成一1:3的配合物,该配合物在修饰电极上本身没有电化学活性,仅覆盖住原有的PCV电活性点,从而使峰电流降低,而峰电位没有变化;因此,在有铝和无铝时,电极过程没有变化,都对应于PCV的电化学行为.我们用电化学方法、扫描电镜、X射线光电子能谱和X射线荧光光谱法对此进行了证明.
The pyrocatechin violet (PCV) modified electrode was prepared on the pyrolytic graphite electrode by adsorption method.It has very good electrochemical activity in the NH_3 · H_2O-NH_4Cl bottom solution (pH8.5) The pulse oxidation peak potential is E pa = +80 mV. The detection of aluminum, except for the decrease of the peak current and the change of the peak potential, is consistent with the decrease of the oxidation peak current in the range of 1 × 10 -8 -1 × The detection limit was 10 × 10 -7 -7 × 10 -6 mol.dm -3 within the range of 1 × 10 -7 -7 × 10 -6 mol.dm -3 and the detection limit was 5 × 10 -3 The actual water sample was measured with the standard deviation of 5.0% (4 × 10 -8 mol · dm -3 Al, n = 8) and ~ (-9) mol · dm -3, respectively. The results are satisfactory.The mechanism of the test was studied after that: (1) PCV modified electrode surface is PCV monolayer adsorption, has good electrochemical activity; (2) aluminum and PCV electrode surface to form a 1: 3 complexes, the complex itself has no electrochemical activity on the modified electrode, covering only the original PCV electroactive sites, so that the peak current decreases, while the peak potential has not changed; therefore, with and without aluminum , The electrode process has not changed, all correspond to the electrochemical behavior of PCV.We use electrochemical methods, scanning electron microscopy, X-ray photoelectron energy This is demonstrated by spectroscopy and X-ray fluorescence spectroscopy.