化学滴液电极对废水中Pb~(2+)测定的初步研究

利用自制的滴液电极,运用循环伏安和方波伏安法,对Pb~(2+)在水/甲基异丁基酮(MIBK)界面上通过双硫腙(HDz)促迁移的反应机制进行了研究.结果表明,该迁移过程为不可逆过程,Pb~(2+)的迁移峰电位为0.122 V,且当Pb~(2+)摩尔浓度为5.0×10~(-7)～4.0×10~(-5)mol/L时,峰电流和Pb~(2+)浓度呈线性相关关系;水相中常见的Na~+等金属离子浓度比Pb~(2+)浓度大百倍时,或水相中常见的Mg~(2+)、Ni~(2+)浓度与Pb~(2+)浓度相同时,对峰电流测定结果产生的干扰都较小(相对误差小于10.0%),但当水相中有Zn~(2+)、Cu~(2+)、Fe~(3+)存在时,即使其浓度都与Pb~(2+)浓度相同,也会对峰电流测定结果产生明显干扰(相对误差分别为-12.2%、-28.7%、-60.3%);以方波伏安法取代循环伏安法进行峰电流测定,以新型绿色溶剂室温离子液体(RTILs)取代四苯硼四丁基铵作为有机相电解质,能极大提高Pb~(2+)浓度测定的灵敏度.

Preliminary study on the determination of lead containing wastewater by novel dropping electrode

The transfer of Pb(Ⅱ) facilitated by dithizone (HDz) presents in the methyl isobutyl ketone across the polarized water/ MIBK interface has been investigated systematically by novel dropping electrolyte electrode using cyclic voltammetry (CV) and square wave voltammetry(SWV). The process is irreversible and controlled by diffusion. The transfer potential is 0.122 V, and the concentration of Pb~(2+) from 5.0×10~(-7) mol/L to 4.0×10~(-5)mol/L is a linear relative to peak current. Traditional organic electrolyte tetrabutylammounium tetraphenylborate is substituted by room temperature ionic liquids (RTILs) 1-butyl-3-methyl imidazolium hexafluorophosphate. The effect of concentration of RTILs on the peak current has been investigated. Determination of heavy metal ion by novel dropping electrolyte using CV and SWV has prospective application in the online and situ-determination of heavy metal ion for its simple, stability and sensibility.