Session: 06-14-01: Biotechnology and General Applications

Paper Number: 113976

113976 - Comparison of Biodiesel/Glycerin Separation by Gravitational Settling and Electrostatic Coagulation 

This paper compares the use of electrostatic coagulation and gravitational settling for efficient separation of biodiesel and its by-product glycerin, which were produced using raw materials such as waste vegetable oil and virgin canola oil. A limited series of experiments were conducted to assess whether the use of no sonication or continuous or pulsed sonication at various power levels, was conducive towards achieving high yields. Titrations were performed on the vegetable oils to determine the free fatty acid (FFA) percentage and the optimal amount of catalyst to be used. The tests utilized an oil-to-methanol volume ratio of 6:1 and an operational temperature range of 50-60⁰ C. Separation by gravity allowed each fluid to settle into different layers based on their respective densities. A video camera was used to record the gradual separation of the mixture into differently colored layers after it had been decanted from the biodiesel reactor and poured into a transparent graduated cylinder. To reduce the separation time and improve the quality of biodiesel, the use of high-voltage separation was investigated. A circuit rated at 1.5kv was designed and constructed to impose a DC voltage potential across the biodiesel/glycerin mixture. The positive and negative steel wire meshed electrodes were immersed in a clear acrylic separation tank containing the mixture. A digital data acquisition system was utilized to measure the instantaneous voltage and current associated with the mixture as separation occurred. The separation process was deemed to be complete when either the electrical resistance across the load or the power dissipated across the load, approached an asymptotic limiting value. In every instance, the required time to achieve complete separation was recorded. Excessive sonication was often judged to be detrimental when poorly controlled. In many cases, it resulted in a highly viscous mixture comprised of colloidal solids that were difficult to separate by either electrostatic coagulation or gravity settling. Generally, quantified sonication improved the biodiesel yield marginally. Ultrasonication rated at 500W, 20kHz set at 75% amplitude was applied no more than 20 minutes in this study. For select cases considered in this paper, it was determined that the use of electrostatic coagulation yielded significant reductions in the time required to fully separate the biodiesel and glycerin, as compared to gravitational settling. Approximately 90% of the separation obtained by electrostatic coagulation was observed within 150 s, for those cases that yielded biodiesel which passed the 27/3 test. This research demonstrated that optimal electrostatic separation depended on the initial mixture composition, and the amount of current and voltage exerted during the fluid separation.

Presenting Author: Saanyol Ityokumbul Igbax TENNESSEE TECHNOLOGICAL UNIVERSITY

Presenting Author Biography: Mechanical Engineer, thermal fluid and property analyst, Design analysis, Quality assurance and Safety controls. Expert Experimental and Statistical processing of Energy / Fluid flow Systems. Seeking full time position in Manufacturing related position with preference in production, research and development beginning in June 2023

Authors:

Saanyol Ityokumbul Igbax TENNESSEE TECHNOLOGICAL UNIVERSITY
Daniel Swartling Tennessee Technological University
Elsawy Ahmed Tennessee Technological University
Stephen Idem Tennessee Technological University