Synthesis of Polyaniline Coated Optical Interferometer Fiber as a Sensor for Nitrate Detection

Yusuf Sulieman @ Joseph Soon, Adam Soon (2018) Synthesis of Polyaniline Coated Optical Interferometer Fiber as a Sensor for Nitrate Detection. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Nitrate (NO3-) had affected our lives in many different ways. Development of sensor to detect the presence of NO3- is crucial. However, conventional method of NO3- detection possesses a number of disadvantages. Limitation from conventional method could be overcome by applying conducting polymer (CP) and optical interferometer as a sensor for NO3- detection In this study, Polyaniline (PAni) coated optical interferometer sensor in Mach-Zehnder (MZI) setup was used as a device for NO3- detection. PAni with different Aniline to AOT ratio (Ani:AOT) of 5:3, 5:5, 5:7 at different polymerization temperature (0 ˚C and 25 ˚C) were synthesized and studied. Chemical structure of PAni was characterized and confirmed with FTIR and UV-Vis. Electrical conductivity of PAni was measured by using Four Point Probe method. PAni with Ani:AOT ratio of 5:5 synthesized at 0 ˚C possess the highest conductivity (8.595 x 10-2 S cm-1) because of its long linear PAni chain and high amount of dopant that allow fluent electron movement without any hindrance. PAni (5:5) 0 ˚C also possesses the highest sensitivity (0.018) among all because the linear PAni chain allow its active site to be exposed fully for interaction. The interaction between PAni and NO3- was studied by using UV-Vis and FTIR where the potassium ion (K+) will revert AOT back to its salt form this converting quinoid group of PAni to benzenoid.