CHEMICAL ENGINEERING TRANSACTIONS VOL. 56, 2017 A publication of The Italian Association of Chemical Engineering Online at www.aidic.it/cet Guest Editors: Jiří Jaromír Klemeš, Peng Yen Liew, Wai Shin Ho, Jeng Shiun Lim Copyright © 2017, AIDIC Servizi S.r.l., ISBN 978-88-95608-47-1; ISSN 2283-9216 Flammability Assessments of Sonication Process in Organic Mixture Nur Amira Hasnul Hadi a , Arshad Ahmad* ,b , Tuan Amran Tuan Abdullah b , Adnan Ripin b a Faculty of Chemical & Energy Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Malaysia b Centre of Hydrogen Energy, Institute of Future Energy, Universiti Teknologi Malaysia, 81310 Johor Bahru, Malaysia arshad@cheme.utm.my The prospect of sonication phenomenon in facilitating separation of azeotropic mixtures calls for more detailed study towards developing an intensified distillation system. One important element that require in depth consideration is safety since ultrasound is a potential ignition source with a low threshold value of 1 mW/mm 2 . In this study, the aim is to investigate the potential of fire hazards that may be introduced by sonication when used in the environment of flammable organic liquid. Simulation study in MATLAB programming environment is carried out based on a mathematical model developed using first principle. Simulations of bubble conditions covering its whole life cycle regimes are carried out and validated with experimental works. Evaluation is made for an extreme condition where the ultrasonic waves are focused directed towards a stainless steel target material immersed in ethanol-water mixture. As sonication occurs, bubbles form slowly by rectified diffusion process with radius of 6 μm, and move toward the metal target. The experimental results revealed that cavitation bubbles filled with explosive vapor are not ignited. This is consistent with the simulation study where the maximum energy released during the bubble collapse is found to be small, which is 0.19267 pJ compared to minimum ignition energy of the liquid at 0.23 mJ. This concludes that the focused ultrasound wave in organic liquid does not trigger ignition, thus suggesting the ultrasonic distillation system is potentially. 1. Introduction In recent years, separation of liquid mixtures has become one of the most important tasks in process industry. From all separation technique available, distillation has been the most common method used. Because distillation offers many processing advantages and mostly used, it still remain as the preferred process. For mixtures that have azeotrope, separation process must have a specially chosen chemical to eliminate the azeotropes points, namely entrainer (Ripin et al., 2009). Since azeotropic mixture could not be separated using conventional distillation, it requires a new method for the separation. Over the last few years, a large number of scientists has been working on chemical intensification process and has developed an interest in ultrasonic distillation (Stankiewicz and Moulijin, 2002). The uniqueness of ultrasound is that it is only operated in the presence of liquid to transmit its energy to enhance the physical and chemical change of a liquid medium. Acoustic cavitation is the major phenomena that arise from the propagation of ultrasonic waves in liquid (Ashokkumar, 2011). Power of ultrasound enhances the chemical and mechanical effect by the generation and destruction of cavitation bubbles occur during the process (Contamine et al., 1994). Growth and collapse of bubble in sonication has yield the energy transfer from ultrasonic transducer to the vapour inside the bubble (Gong and Hart, 1998). During this time, extremely high pressure in orders of hundreds of atmosphere and high temperature up to 5,000 K are generated inside the bubble. Since ultrasound are considered to be an ignition source by International Standard, this separation method has reported no explosion neither fire accident in conjunction to ultrasound. However, incendivity of acoustic cavitation on vapour liquid equilibrium in ultrasonic distillation is not yet to be to be study. This present work is undertaken to determine whether will sonication during ultrasonic distillation triggered ignition. DOI: 10.3303/CET1756233 Please cite this article as: Hadi N.A.H., Ahmad A., Abdullah T.A.T., Ripin A., 2017, Flammability assessments of sonication process in organic mixture, Chemical Engineering Transactions, 56, 1393-1398 DOI:10.3303/CET1756233 1393