Studies On Functionalization Of Multi-walled Nanotubes And Optical,Electrochemical Sensor

The aim of this dissertation is to explore the functionalization of Mutli-Walled carbon nanotubes (MWNTs). Magnetic Fe nanoparticle functionalized water-soluble MWNTs were prepared, and used for the removal of aromatic compounds in water and re-use; MWNTs porphyrin modified serve as an efficient electron acceptor; we prepared a new Tin film sensor for heavy metals and a CO₂ fluorescent sensor. The main contents can be summarized as follows:1. The head of MWNTs were opened, when they were purified. MWNTs were dispersed in Fe(NO₃)₃·9H₂O solution with the help of an ultrasonic bath. After draining excess water on a rotary evaporator with a vacuum pump and washing with distilled water, the resulting materials were reduced using H₂ at 560℃and at 900℃successively. The inner empty cavity of the nanotubes has magnetic nanoparticles. We used the carbon radicals to modified the MWNTs and made them water-soluble. Finally. We got the magnetic Fe nanoparticle functionalized water-soluble MWNTs for the removal of aromatic compounds in water and re-use.2. Antenna-acceptor composites of porphyrin and its complexes(Co²⁺, Zn²⁺) covalently linked mulitwalled carbon nanotubes(MWNTs) as many light-harvesting antenna of MWNTs was constructed by free radicals generated using decomposition of azodiisobutyronitrile (AIBN). MWNTs were derivatized up to about 60 wt. % with functionalizing moieties of the porphyrin. UV-Visible spectroscopy and the absorption and fluorescence of these complexes show that the carbon nanotubes serve as an efficient electron acceptor3. A tin film electrode (SnFE) was reported for the first time as a possible alternative for electrochemical stripping analysis of trace heavy metals. The SnFE was prepared in situ on a glassy carbonsubstrate electrode and employed in combination with either anodic stripping voltammetry or stripping chronopotentiometry in nondeaerated solutions of 0.1 M acetic acid. Several key operational parameters influencing the electroanalytical response of SnFE were examined and optimized, such as deposition potential, deposition time, and composition of the measurement solution. The SbFE exhibited well-defined and separated stripping signals for both model metal ions, Zn(II),Cd(II) and Pb(II), surrounded with low background contribution. The electrode range from 20 to 140 ppb for both test metal ions for Pb(II) obtained after a 120 s deposition step, and good reproducibility. When comparing the SnFE with the commonly used bismuth film electrode recently introduced , the newly proposed electrode offers a remarkable selective to detect the Pb(II) hence contributing to the wider applicability of electrochemical stripping techniques in connection with "mercury-free" electrodes.4. The sol-gel process was used to prepare organically modified silica glass in which the fluorescent pH-sensitive reagent 1-hydroxypyrene-3,6,8-trisulfonate was entrapped. An ion-pair approach was used to incorporate the hydrophilic dye in the hydrophobic silica glass. Good sensitivity to gas phase carbon dioxide was observed in the 0-30% range, with rapid response and we used the principle of Mie scattering TiO₂ was doped in the silica glass, the sensitivity for the same concentration of CO₂ was markedly improved compared with the non doped TiO₂ silica glass.