Corrosion Microbial, Diseño De Laboratorio (Ingles)

Design N°1


Aim: Investigate an aspect of corrosion


Research question: How does microbial corrosion, which is in naval or marine industry depends on the quantity of bacteria Ferrobacillusferrooxidans present in salt water.

Hypothesis: Ferrobacillus ferrooxidans directly oxidizes iron to iron oxides, iron hydroxides and iron sulphides. This process produces rusticles in marinestructures such as ships. An example of this microbial corrosion is the particular case of the Titanic. When Fe is oxidizied 2 electrons become free, and when bacteria establish contact with water it frees2 hydrogen protons. The free protons become attracted to the oxygen that sulphate (present in the solution that represents salt water) posses in order to form a water molecule; as a consequence ofthis, sulphate becomes an ion (S²¯) and combines with Fe, creating a final product of corrosion which is FeS. The following design will have as a hypothesis to analyze the effect of Ferrobacillusferrooxidans on a piece of iron (ship representation); by varying the amount of bacteria certain aspects of the reaction, such as products of corrosion, will be analyzed. This will be measured by removingand weighting the oxide produced in the Fe tablet.

Reaction (summarized) : Fe² (aq) + S²¯(s) FeS (s) (iron sulphides)


Variables:

Independent: mass of the bacteria added tothe solution. Make several tests varying the mass between 0.5 and 10.0 grams
Dependant: mass of oxide produced; once the rusticles are formed and the change of colour of iron is evident, with the aidof a knife remove the oxide from the iron and weight it.
Controlled: - Dimensions of iron piece (15cm x 15cm approx.)
- Salty solution (prepared with 500cm³ of tap water and 10grams of salt)
- Temperature (room temperature for all the experiences)



Materials:

1) Tap water
2) 10 grams of Salt
3) Iron piece approx 15cm x 15 cm
4) Knife...