I would to like to supress the light sensitivity of silver chloride particles prepared in the suspension form. A patent says " binding it to titanium dioxide to silver chloride could help. It also explains that there will be an oxygen vacant site in titania which helps to interact with silver chloride leading to stabilization of the compound and theerby may contribute to suppression of light sensitivity "
Does this principle applies to silica in place of Titania.
Kindly help me to understand this better.
Thanks.
Silver chloride is not very light sensitive, since its band gap contains most of the visible spectrum. It is colorless when not sensitized. It does exhibit a volume sensitivity to blue light and UV, so preparing it as very small crystals will decrease its sensitivity. The absorption coefficient is very low below 320 nm at room temperature. In this blue region of the visible, absorption is assisted by phonons, so this mechanism of excitation decreases with decreasing temperature.
When it does absorb a photon that photoreduces silver ion to zero valent silver atoms, the most probable place for such a so called sub-latent image spec to reside is someplace on the crystal surface. Therefore, if you keep the continuous phase highly oxidizing, such reduced specs can be readily oxidized. Ferricyanide will work, as will many other common oxidants. So called reversal films worked on the principle of developing this surface latent image. A high Cl2 concentration in water will also suppress hole formation, but will make you think you are visiting a public swimming pool.
Titania is a good photocatalyst for producing electron-hole pairs and in suspension it will photo-oxidize most organics down to CO2. Silica does not have a comparable band structure and is not photoactive.
A good reference examining diverse aspects of silver halide physics and chemistry is T. H. James (editor), The Theory of the Photographic Process (4th edition), Macmillan, New York, 1977. May I ask why you want to use AgCl in the presence of light?
Thanks so much Mr. John for your elaborate answer. I am looking into antimicrobial applications of silver chloride onto textiles. In presence of light, it is changing into pink color. Hence, I am also looking for binders/polymers to bind Titania to silver chloride in suspension.
I developed an alternative approach to using silver salts as antimicrobial materials. One can easily spray coat, dip coat, textiles with silver surfactant solution. This is a very direct and simple alternative approach. See attached patents.
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