J. Eng. Technol. Sci., Vol. 53, No. 3, 2021, 210309 Received June 11 th , 2020, Revised December 28 th , 2020, Accepted for publication April 1 st , 2021. Copyright ©2021 Published by ITB Institute for Research and Community Services, ISSN: 2337-5779, DOI: 10.5614/j.eng.technol.sci.2021.53.3.9 Optimization and Modeling of Ammonia Removal from Aqueous Solutions by Using Adsorption on Single-walled Carbon Nanotubes Arsalan Jamshidi 1 , Soheila Rezaei 2 , Ghasem Hassani 2, * , Roohullah Jahanpour 1 & Hossein Marioryad 1 1 Department of Environmental Health Engineering, Yasuj University of Medical Sciences, Shahid Dastjerdi St, Imam Hossein Sq., Yasuj 7591875114, Iran 2 Social Determinants of Health Research Center, Yasuj University of Medical Sciences, Shahid Dastjerdi St, Imam Hossein Sq., Yasuj 7591875114, Iran *E-mail: ghhassani64@gmail.com Highlights:  The highest adsorption was obtained in alkaline conditions (pH = 9.5) with a yield of 90%.  The Freundlich isotherm had the highest conformity with the data and is considered the best model for describing adsorbent properties.  First-order kinetics had more conformity with the data compared with second-order kinetics. Abstract. Due to the health effects of ammonia as an environmental pollutant, such as its odor, corrosion, algae phenomenon, etc., a method should be adopted to remove it from wastewater. In this study, removal of ammonia from hypothetical wastewater was investigated using adsorption on SWCNTs. The Design-Expert software was used to design the experiments and optimize the parameters that are effective in the adsorption performance of carbon nanotubes (CNTs), such as contact time, adsorbent dosage, pH, temperature, and ammonia concentration. The results revealed that the maximum adsorption with a performance of 90% was attained at a pH of 9.5. In addition, the adsorption performance was enhanced by increasing adsorption time and adsorbent dosage. Furthermore, increasing the temperature and the adsorbate quantity led to a decrease in the adsorption performance. Keywords: ammonia removal; carbon nanotubes; isotherm; kinetics; response surface methodology. 1 Introduction Urban development, the emergence of a variety of industries, the increased level of social welfare and other factors have caused irreparable damage to the environment. One of the major environmental sources that have been