Will activated charcoal adsorb aspartame from the GI tract? I have found no research to confirm that charcoal does, though I suspect it will. But, digestive acids quickly break down aspartame into several residual chemicals, including aspartic acid, phenylalanine, methanol, and further breakdown products including formaldehyde, and formic acid. Activated charcoal does adsorb phenylalanine, methanol, formaldehyde, and formic acid. Therefore, activated charcoal, taken before or after ingesting foods with aspartame, should adsorb these toxic waste products in the GI tract.
One should remember that specialized kidney and liver dialysis machines employ a bed of granular charcoal in the blood purification process when the kidneys or liver are unable to perform their jobs. If technology has successfully harnessed the cleansing action of charcoal to purify toxic blood it is reasonable to expect a significant benefit from taking charcoal orally or applying charcoal as a poultice or in a bath to detoxify the body generally. Charcoal does bind hundreds of toxic compounds (including mercury and other heavy metals - especialy with Bone Charcoal), digestive wastes, and even some microorganisms.