Preparation of Novel Commercial Polyaniline Composites for Ammonia Detection Muhammad Musa Jusoff Albar 1,a , Nurul ‘Ain Jamion 1,b , Siti Nor Atika Baharin 1,c , Muggundha Raoov 2,d and Kavirajaa Pandian Sambasevam 1,e * 1 School of Chemistry and Environment, Faculty of Applied Sciences, Universiti Teknologi Mara, Cawangan Negeri Sembilan, Kampus Kuala Pilah, 72000 Kuala Pilah, Negeri Sembilan, Malaysia 2 Department of Chemistry, Faculty of Sciences, University of Malaya, 50603, Kuala Lumpur, Malaysia a Musa.jusoff95@gmail.com, b ain7059@uitm.edu.my, c atikabaharin@uitm.edu.my, d muggundha@um.edu.my, e kavirajaa@live.com* Keywords: Conducting polymer, crab shells, mussel shells, egg shells, sustainable waste management. Abstract. Polyaniline (PANI) is one of the unique conducting polymers due to tunable conductivity, acid-base chemistry and optical properties. In this study, commercial PANI was used to prepare PANI/shell composites to enhance the sensitivity of PANI in ammonia (NH3) gas detection. Three types of waste shells were utilized to incorporate into the PANI matrix such as egg shells (ES), crab shells (CS) and mussel shells (MS). The characterizations were done by Fourier transform infrared (FTIR) and ultraviolet-visible (UV-Vis) spectrophotometer. FTIR spectra confirmed the presence of CaCO3 in the PANI/shell composites’ backbone. Whereas, UV-Vis spectra further confirmed the PANI/shell composites were in the doped state by exhibiting a characteristic peak at ~790-820 nm. Sensor performance of commercial PANI and PANI/shell composite films were studied in terms of sensor measurement and sensor performances (selectivity, reusability and long-term stability). The sensor performances of commercial PANI, PANI/ES and PANI/CS exhibited correlation coefficient of >0.95. In addition, commercial PANI and PANI/CS films exhibited good selectivity for NH3 gas detection in the presence of interfering gases. In conclusion, PANI/shell composites were successfully prepared for NH3 gas detection and PANI/CS exhibited the highest sensitivity compared to other films. Introduction Ammonia (NH3) gas has been identified as a toxic compound with its atmospheric lethal concentration of 30 ppm and it becomes extremely lethal above 500 ppm [1]. The rise of NH3 gas negatively impacts environmental and public health and climate alteration. For example, when inhaled or in contact in low concentration, will cause irritation while at high concentration can cause temporary blindness and mucous membrane injury [2]. For these reasons, it is important to have a clear view of the sources, deposition and atmospheric behavior of NH3 gas [3]. The main source of NH3 gas release is the NH3-based fertilizer usages in agricultural activities. Industrial processes, automobile emissions and volatilization from soils and oceans also show traces of NH3 in the atmosphere [3]. There were many successful attempts/materials were made to detect NH3 in both gaseous and aqueous states. Among the available materials, the use of polyaniline (PANI) possesses an important role in NH3 gas detection. It’s due to the easy synthesis, environmental stability and unique acid-base chemistry of PANI [4]. Besides that, PANI works the best in the presence of inorganic substances at its backbone which gives the hybrid properties to the material. However, no reports were found in utilizing waste shells as hybrid materials in the PANI backbone. Waste shells such as egg shells (ES), crab shells (CS) and mussel shells (MS) contain abundance of calcium carbonate (CaCO3) mineral. The advantage of using inorganic fillers such as CaCO3 is to fill up the void spaces at PANI backbone where the filler’s ions would get stabilized by polar groups of PANI Solid State Phenomena Submitted: 2019-08-20 ISSN: 1662-9779, Vol. 301, pp 124-131 Revised: 2019-11-28 © 2020 Trans Tech Publications Ltd, Switzerland Accepted: 2019-11-28 Online: 2020-03-10 All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications Ltd, www.scientific.net. (#534216023-13/02/20,07:19:39)