Hi,
Trying to write up an assignment on this, but seem to be going in cicles with the charges and how capilary action works on a solvent (in this case propanone with petroleum ether), which in turn pulls up the pigments.
As I see it, the OH groups in cellulose are negatively polar, which attract the Oxygen in Propanone (isn't oxygen always -ve though??). The hydrocarbon tail of propanone pulls the petroleum ether hydrocarbon with it, through dispersion, which in turn pulls the pigments???
I think I've got quite confused over this.
Any speedy clarification would be amazing.