Can an adopted child be emancipated at 16 years old and be re adopted?

It is very unlikely that a court would emancipate a 16 year old and then allow them to be adopted. If the child is in trouble or danger, the court or child services can ensure they are taken to a safe place if the parents were not a viable option.

Why would you want to now this? ether way, I doubt a child would want to be readopted.

Emancipation does not "undo" an adoption, the parental civil relationship still exists. The Emancipation process only changes the level of parental authority level, just as turning 18 does in most states.

The parental authority be reinstated if the emancipated person was involved in an accident and was no longer capable of making rational adult level decisions a court may begin again the prior authority levels and grant guardianship to the parents either temporarily or permanently.