Synthesis, Characterization and Application of Sodium Dioctyl Sulfosuccinate (AOT) Doped Polyaniline (PAni) Sensor in Ethylenediamine (EDA) Detection

Tan, Rachel Sze Huey (2021) Synthesis, Characterization and Application of Sodium Dioctyl Sulfosuccinate (AOT) Doped Polyaniline (PAni) Sensor in Ethylenediamine (EDA) Detection. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Ethylenediamine (EDA) is commonly used in the production of industrial chemicals. Wastewater that produced from the industry will be containing EDA and lead to water pollution. Conventional methods that used to detect EDA in wastewater possessed some disadvantages. Therefore, polyaniline (PAni) sensor for EDA detection was developed due to its low cost, ease of synthesis and adjustable conductivity. In this study, PAni (0 °C) and PAni (25 °C) were synthesized through chemical oxidative polymerization. Sodium dioctyl sulfosuccinate (AOT), ammonium persulfate (APS) and aniline were used as dopant, oxidant and monomer respectively in the synthesis of PAni. The hydrochloric acid (HCl) dopant that used in this study is to enhance the electrical conductivity of PAni. Both PAni (0 °C) and PAni (25 °C) were characterized by using Fourier transform infrared (FTIR), ultraviolet-visible (UV-Vis) spectrometer and resistivity meter. The emeraldine salt (ES) structure of PAni was confirmed by FTIR and UV-Vis spectra. Higher electrical conductivity (1.486 × 10-2 S/cm) was obtained by PAni (0 °C) due to the presence of long linear chain polymer compare to PAni (25 °C). 20 to 100 ppm EDA solution were prepared for application of PAni sensor in EDA detection. PAni (0 °C) gives better sensitivity (0.0023) and R2 (0.98404) than PAni (25 °C). This is due to the presence of branches in PAni (25 °C) will block the EDA from approaching the reactive sites and result in low sensitivity. 0.5 ppm limit of detection (LOD) was obtained by using 3 layers of PAni (0 °C). Moreover, 3 M of HCl, 7 layers of PAni (0 °C) film and 10 ppm of EDA is the optimum condition used for recyclability study. PAni (0 °C) show good recyclability up to 10 cycles with short response time of 7 s and fast recovery time of 5 s. RSD of 11 - 22 % and 14 – 22 % were obtained for real sample analysis using rain and pipe water respectively. FTIR and electrical conductivity were performed as supporting analysis to study the mechanism between PAni film and EDA. It has proven that it is a chemical interaction, converting ES to leucoemeraldine (LE). Thus, an effective PAni sensor is successful developed for EDA detection in this study by showing good sensor performance with proposed mechanism.