Frequency response and activation energy of palm-fatty acids at microwave region

摘要

Microwave technology has the potential to significantly enhance chemical reaction and knowledge of dielectric properties of materials plays a major role in microwave design for any process. In this paper, the dielectric properties (permittivity and conductivity) of palm-fatty acids were investigated. Palm-fatty acids were chosen being the most versatile and sustainable source of raw materials, also considered as the "gate-way" to other oleochemicals derivatives. Thus, the dielectric properties of commercial palm-fatty acids from various sources in flakes and liquid states were determined within the frequency range of 0.2 GHz to 4.5 GHz at temperature range of 303 K and 443 K (stabilized within 1 degrees C). The effects of temperature, moisture and unsaturation structure of palm-fatty acids on dielectric properties were also investigated. Real part of dielectric permittivity (dr) of all the palm-fatty acids increased with increasing temperature from 303 K to 443 K with correlation coefficient, R-2 > 0.95 to linear function; depending on temperature and moisture content of the palm-fatty acids. The conductivity increased with increase in temperature and following the model-fitting approach of Arrhenius equation with correlation coefficient (R-2 > 0.85) for all the measured samples. The calculated activation energy (Ea) for all measured samples was in the range between 0.06207 eV and 0.16442 eV. Hence, the data calculated would be useful to determine the quality of the palm-fatty acids and to specify their requirement for transportation, storage and process. Moreover, the information will also be useful in the design of a microwave (MW) reactor system for oleochemical downstream process as it is dependent on the dielectric properties of the materials being processed. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.