This disclosure describes systems, methods, and devices for phytochemical extraction. One example extraction system includes two solvent columns, a material column, and a dewaxing column. The solvent columns store and provide solvent for stripping target chemicals from plant material in the material column. The solvent mixed with target chemicals passes into the dewaxing column, where the target chemicals are separated from waxes and lipids. Cooling is applied to elements of the system by way of an open-loop CO2 refrigeration method. Solvent is moved from the solvent columns to the material column by creating a pressure differential between the two solvent columns.