Iam a maths student so forgive my lack of knowledge, for a project Iam doing I need some information.. Is there such thing as a proton filter? eg a device that could take in as an input different types of gas (like oxygen) and output just protons? if there isn't something like this, is a device theoretically possible? and any idea how much energy would be required to do so? Thats probably too general... but any help would be ace!!