The flotation experiments were conducted in a
2 1 Denver flotation cell at a rotational speed of
about 1300 rpm. The 150-250 g of the plastic
sample (promptly treated with the alkaline solution,
rinsed, and conditioned with the plasticizer
solution) was mixed with 1.8 1 of tap water,
Rhodasurf 91-6 surfactant (C9- 11 ethoxylated
alcohols) received from Rhone-Poulenc was used
as a frother at a concentration of 15-30 mg/l, in
all flotation experiments. The pH of the solution
was measured with a pH meter. In selected experiments
the pH of the solution was adjusted to a
desired level using l-5 M NaOH solutions. The
suspension of plastics was conditioned with the
frother for about 2 min before the flotation experiments.
The froth floated PVC product was collected
over 8 min, screened, rinsed with water, and
dried.