Sensor Performance of Polyaniline (PAni) Film in Ethylenediamine (EDA) Detection Using Different Types of Acid Dopants

Yap, Pei Jun (2023) Sensor Performance of Polyaniline (PAni) Film in Ethylenediamine (EDA) Detection Using Different Types of Acid Dopants. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

This research focuses on the effects of types of acid dopants on the sensitivity and sensor performance of PAni chemical sensors that had developed by previous research students. PAni chemical sensors with different acid dopants (HCl, H2SO4 and H3PO4) were fabricated and their respective sensing characteristics in EDA detection were compared in this research. PAni/H2SO4 and PAni/H3PO4 samples were re-synthesised and the formation of conducting emeraldine salt form was confirmed by FITR analysis. Based on the UV-Vis and electrical conductivity analysis, PAni/H2SO4 possessed the highest doping level and electrical conductivity of 1.88 x 10-2 S/cm among all PAni due to the lowest pH and two steps dissociations of H2SO4 which produces more protons to protonate the imine groups to yield more mobile carbocation in the PAni backbone and lead to higher electrical conductivity. PAni/H3PO4 possessed the highest sensitivity (0.0038) with a response time of 7 seconds as H3PO4 is a polyprotic acid that allows higher degree of protonation and produces more active sites for EDA detection. PAni/H2SO4 sensor had the lowest LOD (0.169 ppm) among the three PAni sensors. PAni/H2SO4 and PAni/H3PO4 sensors achieved good recovery range from 86 – 133% with RSD% value less than 11% in rain water, pond water, pipe water and mineral water. Furthermore, both sensors were selective toward EDA in the presence of NaOH, NH3, butylamine and benzylamine. PAni/H2SO4 sensor demonstrated higher long-term stability in EDA detection compared to PAni/H3PO4 sensor. The interaction between PAni and EDA had been proved to be chemical interaction via FTIR and electrical conductivity analysis. The sensing mechanism of both sensors was proposed. Overall, PAni/H2SO4 and PAni/H3PO4 sensors have the potential to be a simple and effective analytical tool for EDA detection