Patent CH-698172-B1 (CH)
Inventor: UMINSKY ANATOLY ARKADJEVICH
IPC: B01D11/00
Filed: 2006-02-01
Abstract: Processing waste larchwood to obtain natural products, involves extraction by pulsed injection of ethanol under pressure followed by emulsification, phase separation in a 2-stage vacuum system with metal oxide filters and separate work-up to obtain (a) oligosaccharides and biopolymers from the solid phase and (b) bioflavonoids such as dihydroquercetin plus light wood oils and heavy tars from the liquid phase (after further emulsification, extraction and crystallisation). A method for the complex processing of waste larch wood (I) by milling the wood, extracting natural substances (II) with organic solvent under nitrogen at elevated temperature in a fluidised bed, separating into liquid and solid phases, and isolating the products from both phases. This method involves (a) treating pulverised (I) (moisture content = not more than 20%) with ethanol at not above 36[deg] C and at a solid:liquid ratio of (1:2.5)-(1:3) followed by 5 liquid pressure pulses at 1-minute intervals (by pulsed injection of degassed ethanol at 10 atm for 0.1-1 second) to break up the fibrillar cavities containing tars, oils and bioflavonoids, (b) extracting solubles (II) by pumping the material (plus more ethanol to give a solid:liquid ratio of (1:6.5)-(1: 7)) for 3-5 minutes through an S-emulsifier with a water content of not more than 20 wt.% in the dispersion medium, (c) separating the extraction product into liquid extract and solid phase in a system with two successive vacuum suction outlets each fitted with a metal oxide filter with a pore diameter (PD) of not more than 0.2 micron, the second one being fitted with a vacuum pulse generator producing a residual pressure of 0.1-20 mmHg for 0.8-1 second and then reducing this again so that liquid extract is taken from the second outlet at least 3 times at 1-minute intervals, (d) isolating the final products from the solid phase (arabinogalactan and carbohydrate-lignin biopolymer) and from the liquid extract (separating into 3 layers and consisting of native light wood oils, heavy tars and the aqueous-alcoholic extract of bioflavonoids from which more oil and tar and the pure bioflavonoid dihydroquercetin (DHQ) are obtained), isolating the oils and tars by vacuum distillation of the alcohol to a residual level of 3-5 wt.%, (e) emulsifying the bubble residue in 3-5 volumes of deionised water, separating the emulsion into light wood oils, a suspension of bioflavonoids in their saturated aqueous-alcoholic solution and coagulated wood tars, (f) transferring the aqueous suspension of bioflavonoids containing 6-8% dihydrocampherol (DHC) and naringenin (NG) plus the residual light oils and tars and the pure DHQ to an S-emulsifier along with the same volume of n-hexane and treating the mixture for 1.5-3 minutes, (g) separating the resulting emulsion from the n-hexane fraction into layers and then separating the residual light oils and heavy tars from the aqueous-alcoholic extract of bioflavonoids, (h) extracting the latter with an ether with a boiling point not above 60[deg] C, (i) passing the extract through a ceramic or fluoroplastic filter with a PD of not more than 0.2 micron, (j) removing ether by vacuum distillation to the point of cloudiness, (k) adding a 3-fold excess of water, removing all the ether and crystallising at 0 to -10[deg] C to give DHQ hydrate crystals containing 8-16 wt.% DHC and NG, (l) drying to constant weight under reduced pressure (inert gas), (m) making a saturated solution in 96 wt.% ethanol at not above 38[deg] C, cooling to 18-20[deg] C and filtering, (n) passing the filtrate through a column of active carbon (type BAU-A) or other carbon pellets, (o) removing solvent by reduced-pressure distillation (inert gas) at not above 38[deg] C to give a concentrate, (p) filtering, diluting with water to an alcohol content of 9-10 wt.% and cooling to 0 to -10[deg] C, (q) filtering off the precipitate as above, washing with water and vacuum-drying to give 96-98 wt.% DHQ, and (r) recrystallising from aqueous solution (after filtration as above) at about 0[deg] C and then drying under inert gas at up to 38[deg] C to give DHQ with a purity of 98-99 wt.%.