| Environment pollution is increasingly severe coupled with the rapid economicgrowth, a large number of industrial waste water discharge and heavy metalaccumulation intensifying in soil and water. It is a serious threat to biodiversity and thehealth of human beings that heavy metal can enrich through the food chain andbiological. Hence, it is an urgent task to develop rapid and efficient methods for thedetection of heavy metals.Ionic liquids （ILs） are liquid electrolytes composed entirely of ions in the roomtemperature or adjacent temperature. Strong solubility, high conductivity and viscosity,almost negligible vapor pressure, Low toxicity, wide electrochemical potential windowsand high chemical and thermal stability make ionic liquids suitable for manyapplications in the elctrochemical area. Most titanium acid salt materials which aredielectric body can cause the polarization phenomenon under the action of electric field.Strontium titanate and barium titanate with perovskite structure have many goodcharacteristics, such as good catalytic performance, high chemical stability and strongion absorbility, etc. Current studies have shown that metal titanate materials have strongadsorption toward heavy metals, it can be used for the detection of the heavy metal ions.In this paper, an electrochemical sensor based on strontium titanate adsorption materialsand ILs with good conductivity composites has been developed, and has beensuccessfully applied to the determination of heavy metal ions such as Cd （II） and Pb （II）.These results extended the applications of metal titanate materials in determination ofheavy metal based on chemical modified electrodes. The mainly content of this paperincludes:（1） An electrochemical sensor of rapid and sensitive detection of Cd （II） wasdeveloped based on the SrTiO3/ILs composite film modified glassy carbon electrode（GCE） using linear sweep stripping voltammetry. The electrochemical properties of thecomposite film modified glassy carbon electrode were well investigated. The resultshowed that the prepared SrTiO3/ILs composite film exhibited good selectivity andimproved sensitivity for the Cd （II） detections. In the optimized experimental conditions,the linear calibration curves ranged from2.5×10-8to1.7×10-5mol/L （R=0.998） and thedetection limit （at S/N=3） was estimated to be as low as5.0×10-9mol/L after anaccumulation at-1.1V for4min. Finally the method was successfully applied to determine Cd （II） in water samples, and the result is satisfactory.（2） A composite film of strontium titanate （SrTiO3） and ionic liquids （ILs） isintroduced for fabricating a voltammetric electrochemical sensor for the determinationof Pb （II）. The chemically modified electrode could greatly increase the stripping peakcurrent of Pb （II） detections. Under the optimized experimental parameters, a linearresponse is obtained in the concentration range from4.8×10-8to3.7×10-5mol/L （R=0.997） and the detection limit is8.0×10-9mol/L （at S/N=3） of Pb （II）. The method wassuccessfully applied to determine Pb （II） in water samples. Features such as largeelectroactive area, fast electron transfer and low background current make this newcomposite film modified electrode a promising platform for fabricating reliableelectrochemical sensors for other heavy metal ions.（3） A barium titanate （BaTiO3） and Nafion composite film modified glassy carbonelectrode was prepared for the determination of Cd （II） by using linear sweep strippingvoltammetry. The experimental results showed that the BaTiO3/Nafion composite filmcoated GCE could greatly improve the sensitivity of determining cadmium in presentinga markedly increased stripping peak current. Under the optimized conditions, the linearrange is found to be6.0×10-8to1.6×10-5mol/L, with the detection limit of4.9×10-9mol/L. Finally the method was successfully used to detect Cd （II） in water samples.（4） A novel and sensitive electrochemical method was developed based on abarium titanate （BaTiO3）, sodium dodecyl sulfate（SDS）and Nafion composite filmmodified electrode for the determination of Pb （II） by linear sweep strippingvoltammetry. The experimental results showed that the sensitivity and selectivity ofdetermining lead was greatly improved at the Nafion/SDS/BaTiO3composite filmcoated GCE. In the optimized experimental conditions, the linear range is found to be8.5×10-9to4.2×10-6mol/L, with the detection limit of4.9×10-9mol/L （at S/N=3） afteran accumulation at-1.0V for3min. Finally this method was successfully applied todetermine Pb （II） in water sample. |
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