Date: Thu, 13 Sep 2001 20:27:32 -0600
Reply-To: Rachel Cogent <Gnarlodious@EARTHLINK.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Rachel Cogent <Gnarlodious@EARTHLINK.NET>
Subject: Re: Molassas To Fix Rust -- New Scientist Article
In-Reply-To: <4.3.2.7.2.20010913092744.04fbd720@pop.rcn.com>
Content-type: text/plain; charset="US-ASCII"
Hey this is the most interesting thing I have read all week!
Maybe this professor can tell me why my mouth hurts after I eat pineapple.
Entity Derek Drew spoke thus:
Question
I have a friend who uses molasses to clean rust off old iron items
collected from the bush. The rusty iron article is placed in a jar of
molasses solution (nine parts water, one part molasses) and left for two
weeks. After this time, the article comes out clean and almost shiny. What
is happening here?
Answer
Molasses contains chelating agents. These are made of molecules that are
shaped a bit like the claws of a crab--the word chelation comes directly
from the Latin word chele, meaning claw. They can envelop metal atoms on
the surface of an object, trapping them and removing them. Molasses owes
its properties to cyclic hydroxamic acids which are powerful chelators of
iron.
More of these compounds are found if the molasses is derived from sugar
beet rather than cane sugar. The plants from which molasses is made
presumably use these chelating agents to help them extract minerals from
the soil. Interestingly, there are aerobic microorganisms that use similar
cyclic hydroxamic acids to scavenge iron. So plants and microbes appear to
use the same chelation strategy to obtain their daily ration of iron.
The same process is at work when you clean old coins with Vegemite or
cola. The power of chelating agents also explains why the insides of
tomato tins need to be lacquered. The citric acid in the tomatoes would
dissolve the metal of the container if the lacquer were not present.
Household cleaning agents, especially detergents and shampoos, also rely
on chelation. These soften water to make it more effective during the
cleaning process.
Chelation has its uses in medicine, too. EDTA or ethylenediamine
tetraacetic acid is used as a chelating agent to control levels of calcium
in the body and can reduce the effects of mercury or lead poisoning.
Ben Selinger, Department of Chemistry, Australian National University. Ben
Selinger is the author of Chemistry in the Marketplace and Why the
Watermelon will not Ripen in your Armpit (Allen & Unwin)
