Enzymes that Can Make You Rich!!

The Use of Enzymes in Silver Recovery for Black and White Film

By Ken Char


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What are enzymes?


Enzymes are proteins that can help break down substances which usually take a long time to break down. Enzymes are catalysts, meaning they can help speed up reactions that would usually take a long time. Furthermore, enzymes are not consumed in the reaction,Enzyme.jpg nor are they changed, and can thus be used more than once.

Enzymes are specific, however, as their substrates - the materials they want to break down - must fit into the active site, the part where reactions take place. The substrate and enzyme fit like a lock and key, and because of this only certain enzymes can break down certain substrates. Therefore, the enzyme's shape plays a huge role in its fuction.

For a more detailed look at enzymes, please go thi this site.






What does this have to do with film?


Film is, quite simply, a wrapped bundle of gelatin with chemicals inside of it. In black and white film (photos, X-Rays, etc.), silver is the main chemical located in the gelatin as, when exposed to light, the metal turns from white to black.

The main type of enzyme used in silver recovery is called alkaline protease, which is available in both a solid form and a liquid form.

What happens is the film is dissolved in water in a collection tank, and the film is placed in the solution. The enzymes will seperate the silver from the other substances in the film, and the silver will sink to the bottom of the collection tank and can thus be easily retrieved.

Usually, this process undergoes heating, as at a higher temperature, the enzymes will move faster and have an easier time "picking up" the molecules. However, the system cannot be heated too high, as high temperatures can cause the enzymes to denature, or lose their shape. As stated in the previous section, enzymes' shapes are extremely important to their function, and if they denature, the substrate cannot fit into the enzymes, and the silver will not be seperated.



Why use enzymes in this process?


In the past, film used to be burned in order to retrieve the silver from used film. However, this method released foul-smelling gases that were generally harmful to people and the enviornment. Furthermore, as silver is flammable, much of the silver was lost in this process. Because of this, scientists decided to use enzymes to help retrieve the silver, and thus created a more efficient and enviornmentaly-friendly process.