Abstract：The carbon-coated PVC membrane mercury ion selective electrode was prepared using nano-TiO2 as modifier and applied to the determination of Hg2+. The cyclic voltammograms of bare carbon electrode, normal carbon-coated mercury ion selective electrode and carbon-coated PVC membrane mercury ion selective electrode after modification by nano-TiO2 were compared in K3Fe(CN)6 solution with concentration of 1.0×10-3 mol/L. It was found that the redox peak current of carbon-coated electrode after modification by nano-TiO2 increased significantly and have a good reversibility. The response curves of normal carbon-coated electrode and nano-TiO2 modified carbon-coated electrode were compared. The results showed that the Nernst response range of carbon-coated mercury ion selective electrode after modification by nano-TiO2 was wider, i.e., 1.0×10-2-1.0×10-6 mol/L with stage difference of 30 mV/pC. Moreover, the carbon-coated mercury ion selective electrode after modification by nano-TiO2 exhibited wider pH range than that of normal carbon-coated electrode. In addition, the detection limit of modified electrode was lower, i.e., 4.5×10-7 mol/L. The selectivity coefficient of common ions (such as Cu2+, Cd2+, NH4+, Zn2+, Cl－, Ca2+, Fe3+, K+, Na+, I－, Fe2+, Mg2+, Al3+, SO42－, CH3COO－ and NO3－) was less than 0.01. The lifetime of modified electrode at room temperature was about three months. The prepared electrode was applied to the determination of Hg2+ in actual wastewater samples by potentiometric analysis. The found results were consistent with those obtained by atomic absorption spectrometry. The relative standard deviation (RSD) was between 1.9% and 2.4%.
Fan J, Qin Y, Ye C, et al. Preparation of the diphenylcarbazone-functionalized silica gel and its application to on-line selective solid-phase extraction and determination of mercury by flow-injection spectrophotometry[J]. Journal of Hazardous Materials,2008,150(2):343-350.
[2]
王俊平, 李家乐, 王硕, 等. 分散液液微萃取分光光度法测定食品中汞含量[J]. 食品工业科技(Science and Technology of Food Industry), 2012(16): 57-60.
Marguí E, Kregsamer P, Hidalgo M, et al. Analytical approaches for Hg determination in wastewater samples by means of total reflection X-ray fluorescence spectrometry[J]. Talanta, 2010, 82(2): 821-827.
Saint'Pierre T D, Rocha R C C, Duyck C B. Determination of Hg in water associate to crude oil production by electrothermal vaporization inductively coupled plasma mass spectrometry[J]. Microchemical Journal, 2013, 109: 41-45.
Gong J, Zhou T, Song D, et al. Monodispersed Au nanoparticles decorated graphene as an enhanced sensing platform for ultrasensitive stripping voltammetric detection of mercury[J]. Sensors and Actuators B: Chemical, 2010, 150(2): 491-497.
Yue J L, Chen Z H. Preparation TiO2 core-shell nanospheres and application as efficiency drug detection sensor[J]. Nanoscale Research Letters, 2014, 9(1): 1-6.
