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据前人钼催化波启发,我们以钒在苦杏仁酸底液中得氯酸盐催化波(图1)。催化波与pH、苦杏仁酸浓度、氯酸盐浓度的关系分别列于图2、3、4。钒浓度在3×10~(-7)M-1×1M~(-5)M范围内与电流呈线性关系。形成催化波的最宜条件为:0.0025M苦杏仁酸,0.4MNaClo_3,pH=2.7。催化波峰电流与汞柱高度(30—80厘米)无关,温度系数为5.8％(19—31℃),i—t曲线得i∝t~(0.6—0.7)。三角波扫描i-E曲线不呈峰状,均反映了动力波特性。可用Koutecky准一级平行催化反应速率常数公式进行计算。式中催化电流扩散电流。为直线且通过原点,在0.0025M苦杏仁酸0.4MNaClO_3底液中r=4秒时求得速度常数k=2.3×10~4升/克分子·秒。由电毛细管曲线和交流极谱曲线(图5、6)
Inspired by the previous molybdenum catalytic wave, we use chlorate as a catalyst for vanadium in mandelic acid (Fig. 1). The relationship between catalytic wave and pH, mandelic acid concentration, and chlorate concentration are shown in Figures 2, 3 and 4, respectively. The vanadium concentration has a linear relationship with the current in the range of 3 × 10 -7 M -1 × 1M -5 M. The optimum conditions for the formation of a catalytic wave are: 0.0025 M mandelic acid, 0.4 M NaClo_3, pH = 2.7. The catalytic peak current has nothing to do with mercury column height (30-80 cm), the temperature coefficient is 5.8% (19-31 ℃), i-t curve iαt ~ (0.6-0.7). Triangular wave scan i-E curve is not peaked, all reflect the dynamic wave characteristics. Koutecky quasi-first-order parallel catalytic reaction rate constant formula can be calculated. Type of catalytic current diffusion current. For the straight line and through the origin, the rate constant k was found to be 2.3 × 10 -4 liters / mol · sec for r = 4 seconds in 0.0025M mandelic acid 0.4M NaClO 3. From the electric capillary curve and AC polarographic curve (Figure 5,6)