Synthesis and Characterization of H3PO4 Doped Polyaniline (PAni) Sensor for Amine Detection

Yee, Ji Kay (2022) Synthesis and Characterization of H3PO4 Doped Polyaniline (PAni) Sensor for Amine Detection. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Ethylenediamine (EDA) is widely used in large quantities to manufacture a wide range of industrial chemicals. Exposure to high EDA concentrations may cause harmful to human beings. Since polyaniline (PAni) was can be easily synthesized, chemical stability, adjustable conductivity and low cost, it was able to develop for EDA detection. PAni was synthesized at (0 ℃) and (25 ℃) through chemical oxidative polymerization using sodium dioctyl sulfosuccinate (AOT), ammonium persulfate (APS) and aniline as surfactant, oxidant and monomer respectively. Fourier transform infrared (FTIR) spectrometer confirmed both the chemical structures for PAni/H3PO4 (0 °C) and PAni/H3PO4 (25 °C) while ultraviolet-visible (UV-Vis) spectrometer proved that PAni/H3PO4 (0 °C) and PAni/H3PO4 (25 °C) were existed in conductive emeraldine salt form. The electrical conductivity of PAni/H3PO4 (0 °C) was higher (2.91 x 10-4 S/cm) while PAni/H3PO4 (25 °C) was lower (3.08 x 10-5 S/cm) measured by a resistivity meter. This is because when the polymerization temperature is lower, polymer chain growth slower and longer. Longer and linear polymer chain facilitate the movement of π electron, thus enhance higher electricity PAni/H3PO4 (0 °C). Different concentrations from 20 ppm to 100 ppm of EDA solution were prepared for the application of PAni/H3PO4 sensor in EDA detection. PAni/H3PO4 (0 °C) performed better sensitivity, 0.0027 and R2, 0.9472 compared with PAni/H3PO4 (25 °C). When polymerization temperature is higher, the polymer chain growth rapidly and the branches formed. Therefore, the branches blocked the EDA from approaching the reactive sites and hence resulting in low sensitivity and low R2 for PAni/H3PO4 (25 °C). PAni/H3PO4 (0 ℃) that show high sensitivity will be used for sensor performance study. PAni/H3PO4 (0 °C) showed good performance in EDA detection with low LODexp (0.5 ppm) and LODtheo (0.1849 ppm). PAni/H3PO4 (0 °C) showed good recyclability up to 10 cycles with short response time of 7 s and fast recovery time of 5 s. Therefore, an effective and potential PAni/H3PO4 sensor was successfully developed in this research study by showing good sensor performance in the EDA detection