The use of n-polyethereal polypyrroles in preconcentration and surface enhanced raman scattering studies


Thesis Type: Postgraduate

Institution Of The Thesis: Orta Doğu Teknik Üniversitesi, Faculty of Arts and Sciences, Department of Chemistry, Turkey

Approval Date: 2009

Student: BAHAR KÖKSEL

Supervisor: MÜRVET VOLKAN

Abstract:

Polypyrroles containing polyether pseudocages (PI, PII, PIII) have been synthesized via chemical oxidation of 1,5-bis(1,1-pyrrole)-3-oxabutane (MI), 1,8- bis(1,1-pyrrole)-3,6-dioxahexane (MII), and 1,11-bis(1,1-pyrrole)- 3,6,9-trioxaundecane (MIII) using anhydrous FeCl3 in CHCl3. Because as obtained polymer resins did not give any response toward any cations, they were reduced (undoped) using chemical reducing agents. Tetrabutylammonium hydroxide (TBAOH) was found to be more effective in undoping to obtain more reproducible and reusable polymer resins. It was investigated whether the undoped polymer resins were used for the extraction of rare earth metal ions from the aqueous medium. Among them, only PIII resin can extract La(III), Eu(III) and Yb(III) from their aqueous solutions and can be employed for the preconcentration of these metal ions. For batch extraction of La(III), Eu(III) and Yb(III) at neutral pH values, percent recoveries of 98.0, 90.7 and 87.3, respectively, has been obtained by using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) technique. The sorption capacity is found as 1.3 mg of La(III) per gram of PIII resin. The PIII resin could be reused at least five times without significant change in its sorption capacity. PIII has also been synthesized via electrochemical method to be used in the preparation of Surface Enhanced Raman Scattering (SERS) active substrate. PIII has been polymerized on Indium Tin Oxide (ITO) glass by using constant potential electrolysis. In an electrolyte solution containing 0.05M tetrabutylammonium perchlorate (TBAP), 1.2 V vs. Ag wire (oxidation potential of MIII) was applied for coating and then silver particles were deposited on the surface of PIII coated ITO electrode by reducing Ag(I) in monomer free electrolyte solution electrochemically. As an alternative, another SERS substrate was prepared electrochemically by depositing silver particles directly on ITO glass. The performances of prepared ITO-PIII-Ag and ITO-Ag SERS substrates were evaluated with dilute solutions of brilliant cresyl blue (BCB), crystal violet (CV), para amino benzoic acid (PABA), nicotine and nicotinic acid.