Technical Reference #1681

1681.

Separation of Buoyant Particles From an Aqueous Dispersion of Corn Germ Particles Using a Bubble Column Leland C. Dickey; Michael J.Kurantz; Peter Cooke; Nicholas Parris; Robert A. Moreau, U.S. Department of Agriculture, Chemical Engineering Science, 63(1681), (2008)

Abstract:
Experiments were conducted to study the use of a bubble column to separate oil from dispersions of corn germ particles in buffered aqueous solution. Particles and aggregates as large as 1mm which contained oil droplets about 1–2 m in size were suspended in the dispersions. The dispersion was subsequently heated dosed with enzyme and pumped into a bubble column. Buoyant fine particles and aggregates were lifted through the 2.9 L of the dispersion in a column by nitrogen bubbles and were incorporated into a foam layer at the top of the liquid. The foam drained from the column through a port a few cm above the top of the dispersion and was collected and subsequently centrifuged to separate a free oil layer. The oil yields were comparable to those obtained by centrifuging entire dispersions churned in an incubator/shaker without the bubbling and foaming. With only endogenous surfactant present in the dispersion the collected foam comprised a quarter of the dispersion mass and about 3/4 of the dispersion's oil (half as a separate oil layer after centrifugation). The rate of free oil collection was the same whether or not the dispersion was bubbled for several hours prior to foam collection.

Keywords:
bubble column; foam seperation; corn germ; oil seperation

Materials & Methods:
2.4. Measurement of droplet size distribution Samples of the germ dispersion prepared using the standard method described in Section 2.1 and of the foam obtained as soon as the foaming began were taken. Aliquots (50 L) of the suspensions of each sample were placed on 12mm diameter glass coverslips and allowed to dry in a gentle stream of compressed air then inverted onto drops of immersion oil on mounted coverslips of microwell dishes (MatTek Corp. Ashland MA). The dried aliquots were imaged optically with a 100× phase contrast oil immersion lens mounted in an inverted optical microscope (model IRBE Leica Microsystems Inc. Bannockburn IL) coupled to a Leica model TCS SP confocal scanner system. Phase contrast images of sets of thin optical sections (∼ 3 m) were collected in the transmitted light detector channel and converted to extended focus. Size distributions of phase contrast objects in images were measured using the digital image analysis program Fovea v3.0 plug-ins (Reindeer Graphics Ashville NC) for PhotoShop v7 (Adobe Systems Inc. San Jose CA). Images with a scale bar were converted from the Glow Over-Under look-up table in Leica Confocal software to monochrome images in Fovea and calibrated for size. The images were flattened thresholded and the equivalent diameters weremeasured. The 1809 particles were counted from the dispersion sample 942 from the foam sample. The size distributions for the dispersion (A) and foam fraction (B) are shown in Fig. 5.

Microscopic Technique
Optical Microscopy

Cell Type(s)
corn germ particles