Patent GB-1357645-A (GB)
Title: Method of extracting nicotine from tobacco
IPC: B01D11/02
Filed: 1971-09-01
Abstract: 1357645 Extracting nicotine from tobacco HAG AG 1 Sept 1971 [2 Sept 1970] 40802/71 Heading A2C Nicotine removal is effected by use of an inert solvent or solvents either in the liquid state at a pressure from equilibrium pressure upwards, equilibrium pressure being defined as substantially above atmospheric pressure, or in the supercritical state at a temperature between the critical temperature of the solvent and 100‹C. In one process a quantity of tobacco is placed in a vessel 1, Fig. 1, and the solvent, e.g. CO 2 , at super-critical temperature is pumped in by a compressor 3. Solvent leaves the top of the vessel and passes to a vessel 2 wherein it is expanded and cooled to the subcritical state so that it liquefies and nicotine separates out. Vapour above the liquid is drawn off through a heat exchanger 4, where its temperature is raised to at least 35‹C., and recycled by the compressor. In a modification, solvent leaving the vessel 1 is immediately returned thereto by the pump, and a bypass is provided whereby a proportion of the solvent is passed through a vessel corresponding to the vessel 2, or through a sorption column charged with activated carbon, ion exchangers, aluminium oxide, silica gel, impregnated infusorial earth, zeolite, &c. When a sorption column is used the solvent may be super-critical throughout. The apparatus of Fig. 1 may be modified for sub-critical operation in which case the heat exchanger 4 is omitted and the compressor 3 replaced by a liquid pump. In a modification suitable for operation under super or sub-critical conditions with halogenized low-hydrocarbon solvents instead of CO 2  a vessel is charged with tobacco and solvent and then sealed while the contents are heated and agitated. The solvent is then drained through a filter to a condenser from which it is slowly evaporated, the nicotine remaining behind. This process is repeated as many times as necessary to obtain the desired degree of extraction. Fig. 6 illustrates an apparatus in which aroma constituents are first removed, followed by the nicotine, after which the aroma constituents are returned to the tobacco. Super-critical gaseous solvent is supplied by a pipe G to a vessel A containing the tobacco and a circulation is established through valves 5, 6, cooler W2, vessel B in which the gas is liquefied and the aroma constituents separated, valve 8, heat exchanger W4, pump or compressor F, heat exchanger Wl and valves 3, 4. The nicotine is then extracted by circulation through valves 5, 7, heat exchanger W3, vessel D, valve 9, heat exchanger W4, pump F, heat exchanger Wl, valve 1, vessel C containing water, and valves 2, 4. The vessel D contains sulphuric, picric, or silico-tungstic acid or a sorbing agent, e.g. activated carbon, for nicotine removal. The aroma constituents are returned to the tobacco by causing super-critical solvent to circulate from the vessel B through valve 12, heat exchanger W5 and valve 13 to the vessel A where the solvent is brought to the subcritical state. Solvent leaves the vessel A through valves 14, 15, heat exchanger W4 and pump F, whence it passes through heat exchanger Wl, valves 3, 10, 11, 6 and heat exchanger W2 to the vessel B. Alternative solvents are CO 2  admixed with a small quantity of ammonia, N 2 O, SF 6 , CHF 3 , CClF 3 , Ar, CBrF 3 , CF 2 =CH 2 , CF 3 -CF 2 -CF 3 , CF 4 , CHClF 2 , CHCl 2 F, CCl 2 F 2 , CCl 3 F, CFCl=CF 2 , CH 3 -CF 3 .