Method for separation of mixture of polyester and cellulose derivative

A method for the separation of a mixture of a polyester and a cellulose derivative selected from the group consisting of cellulose diacetate, cellulose triacetate and nitrocellulose comprising introducing gas bubbles into a dispersion of a mixture of said polyester and said cellulose derivative, said polyester and said cellulose derivative being solid pieces having a size of 1 to 50 mm, in an aqueous liquid medium in the presence of at least one wetting agent to render the surfaces of the polyester pieces more hydrophilic than the surfaces of the cellulose derivative pieces and at least one flotation agent, whereby said cellulose derivative is floated thereby separating said mixture into said polyester and said cellulose derivative.