NOVELTY - A hydrocarbon feedstock (112) comprising crude oil and organic heteroatom compound, and aqueous solvent are fed into contactor (100), and the pressure and temperature of the extraction mixture in the contactor are set to tune the aqueous solvent to form solvent complex with organic heteroatom compound. The recovery temperature and/or pressure of the vessel are adjusted to decompose the solvent complex in the vessel into carbon dioxide and organic heteroatom compound, and organic heteroatom compound is recovered from the recovery vessel.    USE - Recovery of organic heteroatom compounds e.g. sulfur compounds, nitrogen compounds and organometallic compounds from hydrocarbon feedstocks e.g. crude oil or its fractions. Uses include but are not limited to raw material for harvesting solar energy, and manufacturing organic photovoltaic cells and solar cells, organic LEDs, organic thin-film transistors, and pharmaceuticals.    DETAILED DESCRIPTION - A hydrocarbon feedstock comprising crude oil or its fraction, and at least one organic heteroatom compound chosen from pyrrole, pyridine, quinoline, carbazole, indole, nickel-tetraphenyl-porphyrin, vanadyl-tetraphenyl-porphyrin, thiophene, benzothiophene, dibenzothiophene, and/or 7,8,9,10-tetrahydro-benzo(b)naphtho(2,3-d)thiophene, and an aqueous solvent comprising ionic liquid formed from pressurized carbon dioxide and water are fed into a contactor to form an extraction mixture of aqueous solvent with hydrocarbon feedstock. The pressure and temperature of the extraction mixture in the contactor is established to tune the aqueous solvent to selectively form solvent complex with at least one organic heteroatom compound, and the solvent complex is extracted to a recovery vessel from the extraction mixture in the contactor. The recovery temperature and/or pressure of the recovery vessel are adjusted to decompose the solvent complex in the recovery vessel into carbon dioxide and organic heteroatom compound, and at least one organic heteroatom compound is recovered from the recovery vessel.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of components of system for separating organic heteroatom compounds from hydrocarbon feedstock.    Contactor (100)    Spray nozzles (112)    Hydrocarbon storage unit (130)    Hydrocarbon feedstock (131)    Water storage unit (140)