2022 Annual Meeting
Investigating the Separation Behavior of Plant Protein in Mixtures with Other Compounds Via a Tribo-Electrostatic Technique
Plant protein mixtures were separated into protein- and dietary fiber-enriched fractions using a novel solvent-free tribo-electrostatic separation technique. Binary mixtures of protein with dietary fiber compounds (i.e., cellulose and lignin) at 10%, 30%, 50%, 70%, and 90% protein contents were first fluidized in dry air and tribo-charged in a nylon tube, then fed into a plate-type separation chamber to be separated. The mixtures' separation efficiencies depended on dry air flow rate, tribo-charger tube material, diameter and length, and the electric field strength around the plates used in the separation. The experiments' airflow rate value, tribo-charger size, and plate voltage were 7 liters per minute (LPM), 3/16 in internal diameter, 62 in length, and ±7kV, respectively. Fractions attracted to the negatively charged plate (NCP) were rich in protein and had positive protein enrichment levels based on the mixtures' initial protein. However, the fractions attracted to the positively charged plate (PCP) and those that fell at the chamber bottom (CB) due to gravity were depleted of protein and had negative protein enrichment levels. As the protein composition of the protein-cellulose mixture increased, all fractions experienced a significant increase in protein content with approximately constant protein separation efficiencies. Likewise, the protein-lignin mixtures experienced similar trends of increased protein content in all separated fractions at the same conditions. However, their protein separation efficiencies were reduced as the mixtures' protein composition increased. The protein enrichment level of the NCP fractions obtained from protein-cellulose binary mixtures was significantly higher than the protein-lignin binary mixtures. Furthermore, the protein enrichment level of the NCP fractions was reduced by increasing the protein content in the binary mixtures. The NCP fraction obtained from the 1:9 protein-cellulose mixture had the highest protein enrichment level of 3. A tribo-charge investigation method should be developed to predict the particle-particle interactions in the tribo-charger tube during electrostatic separation to ascribe mixtures' chargeability to protein enrichment and separation efficiency.
Acknowledgments: This project was funded through NSF-HBCU-UP-RIA Grant (#1900894).