Guo Hongwei, Chen Bin, Luo Yingmin, Wang Ruiyang, Tian Qichang, Chang Yanping
School of Chemistry and Environment, Jiaying University Meizhou Guangdong 514015 China
RSC Adv. 2024 Dec 12;14(53):39361-39371. doi: 10.1039/d4ra07034h. eCollection 2024 Dec 10.
The effect of Bi-to-metal ion concentration ratio ( / ratio) on key evaluation indicators, including sensitivity, precision, and cathodic potential range, has been investigated for the determination of Cd and Pb at prepared bismuth film electrodes. Unlike the usual recommendation of at least a 10-fold excess of Hg(ii) for anodic stripping experiments at prepared mercury film electrodes, it is found that the / ratios in the 1-10 range are sufficient to obtain a high determination sensitivity, but that the signal decreases significantly when the ratio exceeds 40. Further analysis shows that the precision of the analytical results is good when the / ratio is in the range of 5-10. The precision is even better in the range of 10-20, but too high a ratio cannot further improve the precision of the results. Therefore, it is recommended to keep the / in the range of 5 to 40 to balance the sensitivity and precision in detection. The study also finds that the optimum cathodic potential range is related to the total concentration of metal ions. Therefore, for metals susceptible to hydrogen evolution (, zinc), additional consideration should be given to inhibiting the hydrogen evolution reaction when selecting the / ratio. This work is the first to investigate the effect of the / ratio on the morphology and thickness of deposits using EIS, SEM, and AFM. It is found that increasing the / ratio leads to an increase in the coverage and thickness of the bismuth film on the electrode surface, which enhances the sensitivity of the determination. However, this change is also accompanied by an increase in the electrode resistance, resulting in a significant decrease in signal when the ratio is too large. In addition, when the / ratio is <5, the precision of the bismuth film electrode is relatively poor due to the rapid increase of the bismuth coverage on the electrode surface. The uneven thickening of the deposit also affects the cathodic potential range. Based on these findings, standard curves with / ratios ranging from 5-25 are prepared and successfully applied to the analysis of river water and wastewater.
研究了铋与金属离子浓度比（/比）对在制备的铋膜电极上测定镉和铅时的关键评估指标（包括灵敏度、精密度和阴极电位范围）的影响。与在制备的汞膜电极上进行阳极溶出实验时通常建议的至少10倍过量的Hg(ii)不同，发现1 - 10范围内的/比足以获得高测定灵敏度，但当该比值超过40时信号会显著下降。进一步分析表明，当/比在5 - 10范围内时，分析结果的精密度良好。在10 - 20范围内精密度甚至更好，但过高的比值并不能进一步提高结果的精密度。因此，建议将/保持在5至40的范围内以平衡检测中的灵敏度和精密度。该研究还发现最佳阴极电位范围与金属离子的总浓度有关。因此，对于易发生析氢反应的金属（如，锌），在选择/比时应额外考虑抑制析氢反应。这项工作首次使用电化学阻抗谱（EIS）、扫描电子显微镜（SEM）和原子力显微镜（AFM）研究了/比对沉积物形态和厚度的影响。发现增加/比会导致电极表面铋膜的覆盖率和厚度增加，从而提高测定的灵敏度。然而，这种变化也伴随着电极电阻的增加，当比值过大时会导致信号显著下降。此外，当/比<5时，由于电极表面铋覆盖率的快速增加，铋膜电极的精密度相对较差。沉积物的不均匀增厚也会影响阴极电位范围。基于这些发现，制备了/比范围为5 - 25的标准曲线，并成功应用于河水和废水的分析。
