Separation of buoyant particles from an aqueous dispersion of corn germ particles using a bubble column

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 1 mm which contained oil droplets about 1–2μm 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 3/43/4 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.