TV advert aired on TV3. This advert explains where the fluoridation chemicals come from.
The New Zealand Institute of Chemistry gives an impartial description of where the fluoridation chemicals come from and how they are manufactured.
| Step 1 – Production of SiF4
The superphosphate production process results in the evolution of carbon dioxide, steam and SiF4. This SiF4 is an environmental pollutant and so is removed from the gas stream and used to produce fluorosilicic acid. |
| Step 2 – Hydrolysis of SiF4
The SiF4 is removed from the gas stream by contacting the gas with water droplets. This water hydrolyses the SiF4 as follows: 3SiF4 + 2H2O → 2H2SiF6 + SiO2 The resultant hydrofluorosilicic acid (H2SiF6) is used for fluoridating drinking water |
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