Optical Ion Sensor. Cheri W. Clavier , Yihui Yang, Alicia Vogt, D. Lynn Rodman, Joseph F. Sinski, Hee-Jung Im, and Ziling Xue* Department of Chemistry, University of Tennessee Knoxville, TN 37996. Abstract.
Cheri W. Clavier, Yihui Yang, Alicia Vogt, D. Lynn Rodman, Joseph F. Sinski,
Hee-Jung Im, and Ziling Xue*
Department of Chemistry, University of Tennessee
Knoxville, TN 37996
Heavy metal ions are used in a variety of industrial applications and many are considered pollutants. Currently, industrial metal ion concentration measurements are mostly determined off-line, using techniques that are usually costly, time-consuming and inconvenient.
We are developing an optical ion sensor through the sol-gel process that will give concentrations of metal ions. Initial work has been carried out to explore the basic properties of sol-gel glasses with various amounts of amine ligand incorporated directly into the sol-gel matrix. The sol-gel preparation process was modified to produce optically transparent monoliths containing either the ethylenediamine derivative NH2(CH2)2NH(CH2)3Si(OMe3)3 (TMSen) or the monoamine ligand HN2(CH2)3Si(OMe)3 using Si(OMe)4 as a cross-linking agent. We have developed a novel gel-preparation process that gives strong, optically transparent monoliths without cracking. In addition, a sensor holder has been designed in a flow cell system that allows spectrophotometric measurements of the sol-gel disk in flowing Cu2+ solutions.
The kinetics of cupric ion uptake by the gels in solutions of various Cu2+ concentrations was studied by measuring the change in the absorbance of the metal:ligand complex over time using UV-VIS spectrophotometry. The gels are regenerated with acid or EDTA, neutralized, and then used in subsequent Cu2+ uptake/ removal cycles. Our studies thus far show the potential of the system in metal ion sensing applications.
We are currently focused on improving the gel regeneration procedure to provide reproducible second, third, and fourth cycle results.
Form gel disks free of amine ligand;
Graft ligand in the 2nd step;
Use ethylene glycol to enhance gel strength;
Develop base-catalyzed process.
Stronger gel disks for flow cell operation and Cu2+ uptake-removal cycles;
Optically transparent sensors.Novel Gel Preparation
Brunauer-Emmett-Teller (BET) Gas Adsorption