Study On The Application Of Carboxylic Carbon Nanotube In The Photometry

Studies on carbon nanotubes (CNT) become a hot topic in the world due to the unique one-dimensional tubular structure and subtle physical and chemical properties of CNT. Compared with other area, the application of CNT in analytical chemistry has been studied recently. In this paper, carboxylic carbon nanotube (c-MWNT) was firstly used in the chromogenic reaction for the determination of metal ions. The main achievements obtained in this research include:1. CNT was purified and modified by HNO₃ and HCl in different proportion. With the help of SEM and FTIR, the optimum way was chosen.2. A new chromogenic reaction for the determination of metal ions with fluorome in the present of carboxylic nonotube has been developed and the mechanism was discussed.With the help of carboxylic carbon nanotube, 2,3,7-trihydroxy-9-(3,5-dibromo-4-hydroxyphenyl) flunrone (DBH-PF) was used to determine the Pb²⁺. A red complex formed in the borate buffer solution at pH range of 9.4¹0.0. The maximum absorption of the complex appeared at 558.0nm, and the apparent molar absorptivity was 5.62×10⁴ L.mol^-1.cm^-1. The linearity of the Pb²⁺ ranges from 1 to 50μg per 25 mL of solution with a correlation coefficient of 0.9996. This method has been applied to the determination of trace lead in cosmetics successfully.A new chromogenic reaction for the determination of copper with 2,3,7-trihydroxy-9(3,5-dibromo-3-hydroxyphenyl) fluorome (DBH-PF) and carboxylic carbon nanotube has developed. In phosphate buffer solution (pH=6.5), copper reacts with DBH-PF to form a red complex. The absorption maximum of the complexis located at 561nm, and its apparent absoptivity is 3.654×10⁴ L.mor^-1.cm^-1 in the presence of CNT. Beer's law is obeyed over the range of 0²0μg.mL^-1 for copper. The method has been applied satidfactorily to the determination of microamounts of copper in Chinese traditional drug .3. The studies and applications of the surfactants become more and more popular. In this experiment, the surfactant (CTMAB)and the c-MWNT were used to help to study the reacting condition and application of DBONPF andPb2+,which improved the sensitivity and stability of the complex and the mechanism was discussed.The results show that with the presence of carboxylic CNT and CTMAB, the color reagent reacts with Pb2+and forms a stable purple complex in the medium of NH3-NH4CI buffer solution(pH=9.6). It remains stable for 20 hours at least. The. absorption maximum of the complex is located at 614 nm, and its apparent absoptivity is 4.81 X 104 L.mor'.cm"1 in the presence of CNT. Beer's law is obeyed over the range of 0.01 - 40 u g/25mL for lead. It has been applied to the determination of trace amount of Pb2+ in industrial wast water.The results suggest that the carboxylic carbon nanotube has remarkable solubilization and hyperchromic effect on the chromogenic system.