How to validate and submit for publication a paper as a graduate student?
Your situation is just like that of any other researcher. Work out your ideas. Write them up with proper citations of past and related work and submit to a journal that might be interested. The journal may be one of those you have found in your work and have cited. 

Your advisor will give you initial feedback on your idea I hope and the editor and referees of the journal will also provide some validation. Your advisors likely have more experience and perspective than either of you, so take their advice about originality and possible importance. But, basically, in order to publish, you just do it and wait for feedback from the journal. Expect, as a minimum to have to rewrite based on reviewer comments.