I am a chemist (in case you can't figure out from my handle)

with extensive experience in concrete prep for accepting a coating.
There are really only two choices - TSP or muriatic acid. If you don't want fumes you are looking at TSP and a stiff brush / broom.
The "cadillac" of coatings is a 2 component epoxy. Concrete (well the Portland cement part of it) is extremely alkaline and will degrade just about any other coating like an acrylic, alkyd etc. over time.
Home Depot and Lowes have two component epoxies which are waterborne and contain little to no VOC's (volatile organic compounds, i.e. solvents). They are not cheap though about $50 a gallon. After you mix the part A and part B you must apply them within the potlife which isn't as hard as it sounds - depending on temperatures you should have at least 2 hours to get a batch applied. It will last forever.