碳糊电极伏安法测定南方石煤中四价和五价钒

Voltammetric Determination of V( Ⅳ )and V( Ⅴ ) in Stone Coal by Use of CPEE

本文用含有四价和五价钒的电活性待测试样、碳粉和粘合剂混合组成的碳糊电极为工作电极,Ag/AgCl为参比电极和Pt电极为对电极组成三电极系统。由伏安曲线测出V(Ⅴ)和V(Ⅳ)的含量。在0.2000g碳粉中测定线性范围为0—16.00mg V_2O_5,0—10.00mg V_2O_4。方法用于石煤 中V(Ⅳ)和V(Ⅴ)的测定,试样可不经分解、分离等化学处理过程。对于含V_2O_4、V_2O_5 0.x—x％的煤样测定其变异系数(n为15—24)分别为5.9—10.0％和2.2—9.3％。

The determination of V(Ⅳ) and V(Ⅴ) is effected by using a carbon paste electroactive electrode (CPEE) which consists of carbon powder, binding material, and the electroactive material which is itself a sample to be determined or a vanadium (V2O5 or V2O4) standard. The electroactive material is subjected to oxidation or reduction by anodic or cathodic polarization under a polarized potential and the polarization curve recorded. The peak current obtained is directly proportional to the concentration of the electroactive material in the CPEE. A linear relationship holds in the range 0-16mg V2O5 or 0-l0mg V2O4 in 0.2g carbon powder. The method is rapid and accurate and has been successfully applied to the determination of V(Ⅳ) and V(Ⅴ) in stone coal samples without a chemical treatment.