Bayer Aktiengesellschaft

Peter Schober

Hans-Dieter Block

Hans-Heinrich Moretto

Peter Schmidt

Werner Ludovici

Uwe Brekau

Hermann Genth

Andreas Nickel

Benno Bohm

Peter Simons

A process is provided for the preparation of aqueous silica sols having a particle size of 27 to 72 nm. by adding fresh acidic silica sol into the reactors of a multi stage cascade reactor wherein the reactors contain aqueous solution of colloidal silica sol of a pH of 8 or above. Each successive stage of the cascade reactor is supplied with overflow from the preceding stage. Alkaline compounds, such as alkaline sodium silicate solution, alkaline potassium silicate solution, sodium hydroxide solution or potassium hydroxide solution, are introduced into the first reactor or first reactors so that a pH value in the range of 8 to 12.5 is established in the reactors.

Continuous preparation of silica sols which contain large particles

Process for the production and concentration of alkaline silica sols containing nonaggregated, spherical SiO.sub.2 particles with a diameter of .gtoreq.1 nm starting with SiO.sub.2 concentrations of 4-8% by weight, using microporous membrane filters.

Process for the production and concentration of silica sols

In the fining of a protein-containing beverage such as a fruit juice or a grape or fruit wine or a must therefor in unfermented, partially fermented or fermented form, wherein silica sol is added to said beverage, and the deposit formed is separated off, the improvement which comprises adding an aluminate-modified silica sol to said beverage, whereby the protein removing and flocculation occurs more readily than with unmodified silica sol. The aluminate is preferably added in the form of sodium aluminate. Optionally gelatin is also added.

Fining with aluminate-modified silica sol

Growing community of inventors

Leverkusen, Germany

Peter Schober