Are you arguing against dualism? What kind of existence could emotions have that is not "rooted" in the material biological world? Emotions are a useful concept that helps explain and predict human behaviour and makes human interactions more predictable/rational. If a person is sad at t0 i know that his answer to go to a party at t0+1 will be lower than if his emotional state was happy at t0. That you can describe emotions by biological processes is inconsequential. See also: https://en.wikipedia.org/wiki/The_Concept_of_Mind