Chemical modification of Graphite Reinforced Carbon (GRC) and ordinary pencil lead for anodic stripping voltammetry - a comparative study

Date

4-2002

Degree

Bachelor of Science in Chemistry

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Norriel S Nipales

Abstract

ABSTRACT

OBCENA, TRISTAN 0. University of the Philippines Los Banos, April 2002. Chemical Modification of Graphite reinforced Carbon (GRC) and Ordinary Pencil Lead for Anodic Stripping voltammetry — A Comparative Study.

Adviser: Dr. Norriel S. Nipales

Two relatively similar carbon electrodes; a 0.5 mm pencil substrate (Mongol HB) and graphite reinforced carbon (GRC) electrode, which is expensive yet excellent, were constructed for the analysis of laboratory prepared solutions of Pb(11). Both electrodes were chemically modified with polyaniline (PANI) to enhance the electrodes' conductivity. The electrochemical behavior of the electrodes was investigated before and after analyte treatment, and afterwards compared to determine whether polyaniline modified pencil lead electrode could be a potential substitute to GRC electrodes. The investigation was carried out using Cyclic Voltammetry (CV) and Differential Pulse Adsorptive Stripping voltammetry (DPAdSV). Cyclic voltammograms revealed the electrodes' region of electro-inactivity. DPAdSV, on the other hand, was used in determining the optimum experimental conditions for both electrodes. The best supporting electrolyte for polyaniline modified electrode (PMPLE) was determined to be 0.1M NH4CI, accumulation time must be at least 150 seconds, and the deposition time must not be less than 270 seconds. The polyaniline modified GRC electrode (PMGRCE) was most effective using 0.1M HCI as the supporting electrolyte, with minimum accumulation time of about 210 seconds, and a deposition time of 150 seconds. Deposition and accumulation times for both electrodes increased with time but it leveled off after reaching a certain period. The effect of deposition potential was also studied; there was no significant trend observed for PMPLE. However, for PMGRCE, an increasing response was noted as deposition potential became more negative. Overall, the results showed that PMGRCE is a much better electrode for lead analysis than PMPLE.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993.5 2002 C4 O23

Document Type

Thesis

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