Depending on the context, antonyms for "mix" could be:
* Separate: If you're talking about physically combining things, separating is the opposite.
* Divide: Similar to separate, but implies dividing into distinct parts.
* Isolate: To keep things apart from each other.
* Sort: To arrange items into categories.
* Unify: If you're talking about combining ideas or groups, unify would be the opposite.
* Simplify: If you're talking about mixing things up, simplifying would be the opposite.
* Clarify: To make something clear and understandable, the opposite of making it confusing.
To give you the most accurate antonym, please provide me with the sentence where "mix" is used.