Systems and methods for cannabis cbd extraction

Abstract

Systems and methods for extracting a compound of interest from plant material, such as a cannabidiol (CBD) from cannabis, are provided. Particularly, the disclosed systems and methods utilize a crude oil to separate water and impurities including fats, sugars, resin glues, chlorophyll, and proteins prior to preparation of a CBD distillate. The systems and methods are operable to remove the impurities from the crude oil with a brine solution and at least one acid prior to distillation. The systems and methods are operable with conventional solvents containing between about 5 wt % and about 8 wt % water.

1 . A system for preparing a purified plant extract, comprising:
 a centrifugal separation unit configured to form a solid residue and a raw extract from a slurry, wherein the raw extract comprises at least one compound of interest and at least most of the liquid solvent;   a filtration unit, comprising a filter assembly, configured to filter the raw extract to remove entrained plant material from the raw extract;   a concentration unit, comprising an evaporator configured to receive the raw extract and heat the raw extract to remove at least most of the solvent therefrom by evaporation to thereby form a concentrated extract;   a settling unit, comprising at least one settling vessel, configured to receive the concentrated extract and cause sedimentation of at least one impurity therefrom;   a decarboxylation and degassing unit, comprising an atmosphere heating vessel and a vacuum heating vessel, wherein the atmosphere heating vessel is configured to receive the concentrated extract from the settling unit, mix the concentrated extract with a brine solution and at least one acid under approximately ambient or atmospheric pressure to remove at least one additional impurity from the concentrated extract, and form a winterized oil without a majority of the at least one additional impurity; and   a short-path distillation unit, comprising at least one short-path distillation apparatus configured to receive the winterized oil from the decarboxylation and degassing unit and distill the winterized oil to form the purified plant extract.   
     
     
         2 . The system of  claim 1 , wherein the centrifugal separation unit comprises at least one centrifugal separator configured to receive solid plant material from a solid plant material source and a liquid solvent comprising ethanol from a separate solvent source, mix the plant material and the liquid solvent to form the slurry, and centrifuge the slurry in the at least one centrifugal separator to separate the slurry into the solid residue and the raw extract. 
     
     
         3 . The system of  claim 1 , wherein the at least one acid includes a phosphoric acid and a citric acid. 
     
     
         4 . The system of  claim 1 , wherein the at least one additional impurity comprises at least one sugar. 
     
     
         5 . The system of  claim 1 , wherein the atmosphere heating vessel is configured to receive the concentrated extract from the settling unit and heat the concentrated extract under approximately ambient or atmospheric pressure to decarboxylate at least a portion of the concentrated oil to form the decarboxylated oil, wherein the vacuum heating vessel is configured to directly receive the decarboxylated oil from the atmosphere heating vessel and heat the decarboxylated oil under sub-atmospheric pressure to form the winterized oil. 
     
     
         6 . The system of  claim 1 , further comprising a static separator configured to remove the at least one impurity or the at least one additional impurity. 
     
     
         7 . The system of  claim 1 , wherein the plant material is a  cannabis  plant material, wherein the at least one compound of interest comprises at least one cannabinoid including cannabidiol or terpene. 
     
     
         8 . The system of  claim 1 , wherein the liquid solvent consists essentially of (i) between about 92 and about 95 wt % ethanol and (ii) water. 
     
     
         9 . The system of  claim 1 , wherein the at least one impurity comprises at least one protein or lipid. 
     
     
         10 . The system of  claim 1 , further comprising a rectification unit, configured to receive evaporated solvent from the concentration unit and recover the solvent for recycle to at least one other unit of the system. 
     
     
         11 . A method for preparing a purified plant extract, comprising:
 (a) contacting plant material with a liquid solvent containing ethanol to form a slurry;   (b) centrifuging the slurry to form a raw extract comprising at least one compound of interest and at least most of the liquid solvent;   (c) filtering the raw extract to remove entrained solid plant material from the raw extract;   (d) concentrating the raw extract by heating the raw extract to remove at least most of the solvent therefrom by evaporation to thereby form a concentrated extract;   (e) precipitating a sediment comprising at least one impurity from the concentrated extract;   (f) mixing the concentrated extract with a brine solution and at least one acid;   (g) washing the concentrated extract, brine solution, and at least one acid with water to remove at least a portion of the at least one additional impurity;   (h) decarboxylating the concentrated extract by heating the concentrated extract under approximately ambient or atmospheric pressure to form a decarboxylated oil;   (i) heating the decarboxylated oil under sub-atmospheric pressure to form a winterized oil without the at least one additional impurity; and   (j) distilling the winterized oil by short-path distillation to form the purified plant extract.   
     
     
         12 . The method of  claim 11 , wherein contacting the plant material with the liquid solvent containing ethanol to form the slurry comprises:
 mixing, within at least one centrifugal separation unit, solid plant material received from a solid plant material source with the liquid solvent containing ethanol received from a separate solvent source to form the slurry,   wherein the slurry is centrifuged within the at least one centrifugal separation unit to form the raw extract comprising the at least one compound of interest and the at least most of the liquid solvent.   
     
     
         13 . The method of  claim 11 , wherein the at least one acid includes a phosphoric acid and a citric acid. 
     
     
         14 . The method of  claim 11 , wherein the at least one additional impurity comprises at least one sugar. 
     
     
         15 . The method of  claim 11 , wherein the mixing the concentrated extract with the brine solution and the at least one acid, the turning at least one additional impurity into the water-soluble electrolyte, and the washing the concentrated extract, brine solution, and at least one acid with water to remove the at least a portion of the at least one additional impurity occurs in a first vessel, and
 wherein the concentrated extract is then heated in said first vessel to form the decarboxylated oil, wherein the decarboxylated oil is heated in a second vacuumized vessel directly connected to said first vessel to form the winterized oil.   
     
     
         16 . The method of  claim 11 , wherein the plant material is a  cannabis  plant material, wherein the at least one compound of interest comprises at least one cannabinoid including cannabidiol or terpene. 
     
     
         17 . The method of  claim 11 , wherein a content of the at least one compound of interest in the purified plant extract is at least about 70% by weight. 
     
     
         18 . The method of  claim 11 , wherein the liquid solvent consists essentially of (i) between about 92 and about 95 wt % ethanol and (ii) water. 
     
     
         19 . The method of  claim 11 , wherein the at least one impurity comprises at least one protein or lipid. 
     
     
         20 . The method of  claim 11 , further comprising rectifying the solvent evaporated in step (d) for recycle to at least one of steps (a), (b), and (c).