Suitable ligands for the preparation of semi- quantitative chemical sensors for Pb (II)

Date

10-2004

Degree

Bachelor of Science in Chemistry

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Norriel S Nipales

Co-adviser

Quennie B. Manimtim

Committee Member

Veronica C. Sabularse

Abstract

A Thiokol rubber-paper based chemical sensor was developed for the analysis of lePb (II). The chemical sensor was made up of strips of substance 20 copy paper, serving as the solid support and coated with thiokol rubber as the ligand for lead (II). Among the six ligands initially used for the study, thiokol rubber was chosen because it gives a colored complex with lead (II). Caffeine, Anthocyanins, Dye Sudan I, and Polyphenylene sulfide show no changes in color upon complexation with lead (II). Xylenol orange showed changes in color upon complexation with lead (II).However, when used as a coating material no color changes were observed upon complexation with lead (II). Thiokol rubber, when coated on a paper, showed a change in color from yellow to brown upon lead (II) complexation. The intensity of the brown color increases with increasing lead (II) concentration. A color chart was constructed using 0 mg/L to 100 mg/L Pb (11) concentration and was used as a basis for semi-quantitative determination of the amount of lead (II) present in an aqueous sample. The thiokol rubber paper-based chemical sensor was also tested with other metals. Changes in color were observed with metals such as As (II), Bi (II), Cd (II), Co (II), Cu (II), Fe (II), and Hg (II). Only the metal lead displayed a distinct brown color compared to other metals which displayed a different color. The effect of different types of solid support and pH were also studied. The substance 20 copy paper showed the most intense brown color compared with the other papers tested using the same Pb (II) solution. More intense brown colors were observed with more acidic Pb (II) solution. Five different water samples were collected and subjected to lead analysis using the developed paper-based chemical sensor. The amount of lead (II) present in each water sample was determined by visually comparing the color formed with that of the color chart. Samples from Laguna de Bay, STP Building, Deep well located at Lower Dampalit, Los Banos. and Bay Breeze Car Wash showed no presence of lead (11). The water sample from the ERG Materials Laboratory was found to have a lead concentration ranging from 30 mg/L to 40 mg/L. The approximate amount was confirmed by Atomic Absorption Spectroscopy (AAS).

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993.5 2004 C4 M33

Document Type

Thesis

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