TiO_2/HAP/MWCNT纳米复合薄膜修饰电极伏安法测定工业废水中邻苯二胺

Voltammetric Determination of o-Phenylenediamine in Industrial Wastewater by An Electrode Modified with Nanocomposite Film of TiO_2/Hydroxyapatite/MWCNT

利用壳聚糖溶液分散纳米二氧化钛(TiO2),纳米羟基磷灰石(HAP)和多壁碳纳米管(MWCNT)制备了新型纳米复合薄膜修饰电极。基于此电极建立了一种无汞、高灵敏度测定痕量邻苯二胺(o-PDA)的方法。采用扫描电镜(SCE)、循环伏安(CV)和交流阻抗(EIS)等方法对修饰电极进行了表征;并研究了o-PDA在修饰电极上的电化学行为和动力学性质。结果表明,o-PDA在TiO2/HAP/MWCNT修饰电极上出现了灵敏的氧化峰(Epa=0.538V),说明纳米复合薄膜对o-PDA的氧化有较好的协同催化作用;氧化过程是一个2电子和2质子参与的不可逆过程,电极过程受到扩散步骤控制,其标准速率常数为1701 s-1;利用此氧化峰可以进行痕量o-PDA的检测,其峰电流与o-PDA浓度在5.0×10-5～1.0×10-3 mol/L范围内呈良好的线性关系,相关系数为0.9976,检出限可达1.0×10-5 mol/L;复合薄膜修饰电极稳定性较好,可用于工业废水中o-PDA的现场快速检测,加标回收率在98.6%～104.6%之间。

A nanocomposite film modified electrode was successfully prepared by dispersing titanium dioxide nanoparticles（TiO2）,hydroxyapatite nanofibers（HAP） and multi-wall carbon nanotube（MWCNT） into chitosan solution.Based on this modified electrode,a mercury-free and highly sensitive method for the determination of o-phenylenediamine（o-PDA） was established.The prepared electrode was characterized by scanning electron microscope（SEM）,cyclic voltammetry（CV） and alternating current impedance（EIS）,and the electrochemical behaviors and kinetic properties of o-PDA on the modified electrode were investigated.The experimental results showed that a sensitive oxidation peak of o-PDA appeared at TiO2/HAP/MWCNT modified electrode（Epa=0.538 V）,which illuminated the nanocomposite film had a good synergistic catalytic effect on the oxidation of o-PDA.Further experiments showed that the oxidation process was an irreversible process containing a two-electron and two-proton reaction.This electrode process was controlled by the diffusion step,and the standard rate constant was 1701/s.Trace level of o-PDA can be determined with this oxidation peak.The peak currents were linearly dependent on the o-PDA concentrations in the range of 5.0×10-5-1.0×10-3 mol/L with correlation coefficient of 0.9976 and detection limit of 1.0 ×10-5 mol/L.This nanocomposite modified electrode had favorable stability and had been applied to the quick determination of o-PDAin industrial wastewater,and the recovery was from 98.6% to 104.6%.