Nanodisperse titanium dioxide, process for the production thereof and use thereof
AssigneeBayer Aktiengesellschaft
InventorsGerhard Wiederhoft, Kai Butje, Peter-Joachim Barenthien, Michael Bodiger, Heinrich Alberts
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Abstract
The present invention relates to nanodisperse titanium dioxide, to a process for the production thereof and to the use thereof.
Claims25
A particulate nanodisperse titanium dioxide having a maximum particle size distribution of between 1 and 10 nm, determined by means of an ultracentrifuge, containing less than 0.1 wt. % of carbon in the form of organic compounds or residues, and having a transparency of at least 99% measured in a 5 wt. % aqueous/hydrochloric acid solution between 400 and 700 nm in 180.degree./d geometry at a layer thickness of 10 .mu.m.
A process for producing a particulate nanodisperse titanium dioxide having a maximum particle size distribution of between 1 and 10 nm, determined by means of an ultracentrifuge, containing less than 0.1 wt. % of carbon in the form of organic compounds or residues, and having a transparency of at least 99% measured in a 5 wt. % aqueous/hydrochloric acid solution between 400 and 700 nm in 180.degree./d geometry at a layer thickness of 10 .mu.m, which process comprises the following steps:
- a) mixing a solution comprising sulphuric-acid and titanyl sulphate at an elevated temperature and an alkaline-reacting liquid until the mixture reacts acidically and forms titanium dioxide nanoparticles;
- or adding an alkaline-reacting liquid and a solution comprising sulphuric acid and titanyl sulphate simultaneously to a vessel, while mixing thoroughly at the elevated temperature, until the resultant mixture reacts acidically and forms titanium dioxide nanoparticles;
- b) cooling the mixture obtained in step a);
- c) flocculating the titanium dioxide nanoparticles formed in step a) by adding a monobasic acid to the thus-cooled mixture obtained in step b);
- d) filtering out the resulting titanium dioxide nanoparticle flocculate formed in step c);
- and
- e) washing the flocculate with a monobasic acid to obtain a precipitate.
A method for degrading an organic pollutant or a biodegradable polymer, which method comprises the step of introducing a particulate nanodisperse titanium dioxide into waste water containing the pollutant or the polymer, wherein the particulate nanodisperse titanium dioxide has a maximum particle size distribution of between 1 and 10 nm, determined by means of an ultracentrifuge, contains less than 0.1 wt. % of carbon in the form of organic compounds or residues, and has a transparency of at least 99% measured in a 5 wt. % aqueous/hydrochloric acid solution between 400 and 700 nm in 180.degree./d geometry at a layer thickness of 10 .mu.m.
A particulate nanodisperse titanium dioxide having a maximum particle size distribution of between 1 and 4.5 nm, determined by means of an ultracentrifuge, containing less than 0.1 wt. % of carbon in the form of organic compounds or residues, and having a transparency of at least 99%, measured on a 5 wt. % aqueous/hydrochloric acid solution between 400 and 700 nm in 180.degree./d geometry at a layer thickness of 10 .mu.m.
A particulate nanodisperse titanium dioxide having a maximum particle size distribution of between 1 and 10 nm, determined by means of an ultracentrifuge, containing less than 0.1 wt. % of carbon in the form of organic compounds or residues, and having a transparency of at least 99%, measured on a 5 wt. % aqueous/hydrochloric acid solution between 400 and 700 nm in 180.degree./d geometry at a layer thickness of 10 .mu.m, wherein the particulate nanodisperse titanium dioxide consists essentially of titanium dioxide and at least one metal contaminant, the at least one metal contaminant being iron, magnesium, aluminum, or an alkali metal.
Dependencies are inferred from the claim text.