Hi Rodedun. I have some very good friends that have allowed me to 'experiment' for want of a better word on their afro hair with the keratin treatment. Unfortunately it did not work for them.
Afro hair has very strong bonds and the ingredients in the Keratin treatments that most people use for the BBD's is NOT strong enough to break them. The reason that afro hair relaxers have chemicals in them as they are necessary to achieve the desired result of straight hair.
I would suggest that you find a reputable salon that deals with afro hair and take advice from them.
(Please note that the reply below from CelebrityHair has been taken from a website called http://www.articlesbase.com
and the author is Suzanne Greenfield. I have pointed this out as I wouldn't want you to be mislead and have an expensive treatment that may not work for you).