Organic solvent with water biomass

Cellulose, the major component of the carbohydrate fraction of biomass is hard to deal with. It is insoluble in most conventional organic solvent and water, which hinders the ease of... 

Hydrophobic substances are soluble in nonpolar solvents, whereas their solubiUty in water is very limited. Many of these substances are also soluble in fats and Hpids and are also called hpophile compounds. Such substances have a tendency to avoid contact with water and to associate with a nonpolar, nonaqueous environment, such as a surface, eg, an organic particle, a particle containing organic material, or the lipid-containing biomass of an organism. 

Lipopholic products are usually separated by extraction of the filtered broth, or the whole culture including the biomass, with water immiscible organic solvents, followed by separation of the solvent extracts and concentration in a vacuum evaporator. Chloroform, dichloromethane and ethyl acetate have been widely used as extraction solvents, however, 4-methyl-2-pentanone (methyl isobutyl ketone) appears to be the solvent of choice in the case of steroid substrates. Hydrophilic products, which cannot be extracted by organic solvents, can be isolated by ion exchange or by selective adsorption to polymeric resins (e.g., Amberlite XAD-resins). Resins of a wide range of polarity are available and lipophilic compounds can also be separated by this method. Final purification is accomplished in the usual way by crystallization, distillation or column chromatography. Preparative HPLC is a powerful tool for purification of small product quantities. 

Water-insoluble solvents. Most alkaloids are commonly present in the plant as organic salts. In order to solubilize the alkaloids the crude biomass extract is made basic by the addition of, for example, potassium hydroxide, potassium carbonate, or ammonia. At the resulting high pH the alkaloids are mainly present in their neutral form. The neutral alkaloids are then easily extracted from the aqueous phase with a water-insoluble organic solvent, for example, dichloromethane or chloroform. 

Acidified water. First the alkaloids are extracted from the biomass with acidified water. At a low pH most alkaloids are protonated and readily soluble in an aqueous solution. Subsequently the extract is made basic, and the neutral alkaloids are extracted from the aqueous phase with an organic solvent. 

Enzyme biocatalysts were as well tested in neoteric solvents e.g., ionic liquids, supercritical CO, fluorous solvents, and liquid polymers) comparative with conventional solvents e.g., water and organic solvents) in order to achieve a greener biotransformation of the biomass into value-added products [122]. The results provided clear evidences that the enzyme catalyst... 

Solvent Extraction of PHAs. The majority of the patented separation processes describe the extraction of PHB from microbial biomass using organic solvents such as chlorinated hydrocarbons (eg chloroform or 1,2-dichloroethane), azeotropic mixtures [eg 1,1,2-trichloroethane with water (65)] chloroform with methanol, ethanol, acetone, or hexane (66), and cyclic carbonates [eg hot (120-150°C) ethylene carbonate or 1,2-propylene carbonate (67)] in which the polymer is soluble. With the wider variety of PHAs which can be produced today, the choice of solvents should be carefully considered. In general, solvents which are suitable for PHB should be equally good for any SCL and MCL PHA. The reverse may not be true. For example, while semicrystalline PHB is insoluble in acetone, MCL PHA will dissolve in it. 

Solvent-based pulping (Organosolv) is still in a very early stage of industrial development. In this chemical pulping method the dehgnification of the biomass (usually wood) is done in an organic solvent or solvent plus water system. There are a variety of processes, which use different solvents e. g. ethanol, methanol, acetic acid, formic acid, often in combination with sodium hydroxide, alkaline sulfite, and/or anthraquinone. 

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