Environmental business

Information on photocatalyst products

Information on photocatalyst productss

Intelligent photocatalyst “Rinko”

Intelligent photocatalyst “Rinko” incorporates peroxide linkage into molecular bonding titania-silica (with -Ti-O-Si- bonding), to which Professor Katsuyuki Nakano (current Professor of Fukuoka University, Faculty of Engineering) is the sole owner of the patent rights.

Characteristics of “Rinko” titania-silica aqueous solution

“Rinko” is a new photocatalytic aqueous solution with improved functions where other functions are also combined, unlike existing simple photocatalytic titanium oxide.  The sections of titanium oxide, silicon oxide and peroxide linkage demonstrate the photocatalytic function, the hydrophilic function, and the absorptive function of the visible region, respectively.

1. The coated film is highly transparent; therefore aesthetic quality of the base material is hard to be damaged.

2. Possible one-layer coating can reduce coating costs.

3. More versatile than coated base materials.

4. A coating method suitable for the base material can be selected.

“Rinko” product line

Product name Color tone Characteristics upon coating Degradability upon coating Degradation characteristics of solution


Peroxo-type titania-silica

Clear yellow Hydrophilic Low Highly visible-light responsive


Anatase-type titania silica

Creamy white Superhydrophilic High Visible-light responsive

*Properties, etc.

Concentration of hydrogen ions / concentration of solids Average particle diameter
pH 6-9 / approximately 1% concentration of solids Various types from 10 nm to 30 nm (P-TS 〜 A-TS)

*There are various types of Ti:Si blending ratio for R-P-TS and R-A-TS.

Six photocatalytic actions of “Rinko”

Photocatalytic mechanism

Organic substances are degraded by utilizing strong oxidation-reduction reaction generated by irradiating ultraviolet light on the photocatalytic surface.  By applying this effect, research has been in progress as a substance that can be used for environmental purification such as disinfection of bacteria, antifouling, etc.

The figure on the right shows a conceptual diagram of photocatalytic mechanism.  Organic substances are eventually degraded as a result of electron trapping.

1. Disinfectant, antibacterial and anti-algae properties

Escherichia coli, Legionella bacteria, Staphylococcus aureus, etc. can be disinfected with the strong oxidability of “Rinko.”  As observed in the photos, bacteria are damaged beyond recognition by using photocatalyst.  Degradation of toxins eluted from corpses was also successfully verified.

■Experiment to disinfect Legionella bacteria (A germicidal lamp is used as a light source.)

2. Anti-odor, deodorization and degradation of hazardous substances

Hazardous substances in a room can be degraded and removed, or deodorized with photocatalyst.  Degradation action of photocatalyst is demonstrated by coating it on the surface of hazardous substances causing odor.  “Rinko” is visible-light responsive, and works effectively.

■Experiment of formaldehyde degradation effects with photocatalytic plaster

The formaldehyde concentration increased along with the increase of room temperature in the room untreated with photocatalytic plaster, while it was constant throughout a year in a room treated with photocatalytic plaster.

3. Antifouling and self-cleaning

By coating “Rinko” on outside walls or the exterior of automobiles, the antifouling function can be expected with combined effects from the hydrophilic property of silica and the function to oxidize and degrade organic substances of titanium.

4. Anti-fog

A mirror in a bathroom gets foggy because water vapor attached on the surface grows into many water drops.  By coating the mirror surface with “Rinko,” it is possible to prevent water vapor from turning into water drops, providing mirrors that do not easily get foggy.

5. Water purification

We are studying an advanced water treatment system including degradation, removal, etc. of harmful organic substances on water, by utilizing ultraviolet light contained in sunlight.

6. Air purification

Clean air is essential to maintain a healthy environment.  Processes used for air purification vary depending on components to be treated.  The photograph is one example, showing a method using a photocatalytic reactor with a germicidal lamp.  Titanium/silica beads are used as catalysts.