Amino-functionalized Mesoporous Silica Modified Electrodes For The Determination Of Heavy Metal Ions

Heavy metal ions pollution has attracted great attention because of its great damage, so the real-time detection of heavy metal ions is very necessary.Electrochemical technique is one of the most attractive methods for heavy-metal ions detection due to its rapid analysis, easy operation, high sensitivity and low cost.However, searching for suitable materials for electrode modification is still a challenge in this field. Mesoporous materials have unique chemical and physical properties, and have been widely employed for the construction of electrochemical sensors. In this dissertation, amino-functionalized mesoporous silica was prepared and then employed as sensing materials for the electrochemical stripping analysis of heavy metal ions. The main results are as follows.Firstly, mesoporous silica was synthesized by sol–gel method and then grafted with amino. The material was characterized by X-ray diffraction(XRD), transmission electron microscope(TEM), X-ray energy dispersive(EDS) and Fourier transform-infrared spectroscopy(FTIR). The experimental results prove the existence of amino functional group in the modified mesoporous silica and the order pore structure remained after modification.Secondly, amino-functionalized mesoporous silica modified glassy carbon(GC)electrode showed high sensitivity for the determination of ultra-trace copper(II)because of its strong physical absorption and chelating ability. Under the optimum experimental conditions, the sensor linearly responded to Cu2+ concentration in the range from 5 to 1000 ng L-1 with a detection limit of 0.9 ng L-1(S/N=3). Moreover, the sensor possessed good stability and electrode renewability.Finally, the electrochemical sensor was used for the simultaneous determination of Pb2+ and Cd2+. Under the optimum experimental conditions, the linear response ranges for Pb2+ and Cd2+ ions are 0.5-250 μg L-1and 50-450 μg L-1. Respectively, thecorresponding detection limits are 0.2 μg L-1 for Pb2+ and 1.0 μg L-1 for Cd2+. It is therefore expected that mesoporous silica can be an excellent candidate for the fabrication of electrochemical sensor to detect ultra-trace heavy metals.