Thursday, June 23, 2011

There is a difference

Many bio-based chemical product companies advertise that their wares are completely identical to petrochemicals of the same type. That's never true. They may be functionally identical, but there's an important aspect that many overlook.

Most everyone has heard of radiocarbon dating - that is, given that Carbon 13 has a half-life of about 6,700 years, you can tell the approximate age of a sample of biomaterial through the relative proportion of 12C vs 13C, since unlike a living organism, a dead one doesn't keep its proportion of 13C constant through biological processes. Now think about the beginning instead of the end.

Petroleum extracted from underneath geological strata are millions of years old. They have almost no 13C left. As a result, the products from petroleum are uniformly lighter than bioproducts, which tend to have the natural background rate of about 1.1% 13C in them. It's the difference between a molar mass per carbon atom of 12.011 vs 12.000, but when you're dealing with huge volumes, turns out it matters, at least to chemical manufacturers.

And that is the end of the only somewhat useless factoid of the day.