FRACTIONATION PROCESS OF LIGNO-CELLULOSIC BIOMASS WITH SOLVENT RECYCLING

Description

Description of the invention entitled: Process of fractionation of ligno-cellulosic biomass with recycling of the solvent Owner: University of Perugia, Piazza Università 5 1, 06123 Perugia, Italy, VAT number 00448820548. Designated Inventors: Leonardo LORENZI, Giacomo FABBRIZI, Mattia JEALOUSY, Andrea NICOLINI. ***** Background of the invention 10 The present invention relates to the field of chemistry and in particular, to a biomass fractionation process ligno-cellulosic for the production of cellulose and simultaneous purification, recovery and recycling of the solvent employed in the said process. 15 State of the art Chinese Patent No. CN112144308 describes a method for refine the cellulosic pulp by treatment with gamma-valerolactone and dissolution of hemicellulose for to obtain the dissolution of the pulp and the obtaining of alpha- 20 high purity cellulose. Chinese Patent No. CN110258151A describes a process for the production of nanoscale crystalline cellulose from lignocellulose which involves oxidizing lignocellulose with gamma photoelectrons to generate free radicals so as to 25 destroy the compact structure of the biomass, removing hemicellulose and lignin from biomass with a co-solvent gamma-valerolactone / water (50:50, v / v) while destroying the non-crystalline region of hydrolyzed cellulose and by carrying out a suction filtration with reduction of the 5 pressure to obtain oxidized crystalline cellulose; and bleaching for 1 hour at a temperature of 50°C with a sodium hypochlorite / sodium hydroxide solution to obtain high purity crystalline cellulose, preparation of a 0.5% (w / v) crystalline cellulose suspension and 10 Ultrasonic dispersion to obtain crystalline cellulose nanometric. Chinese patent No. CN105484083 describes a process of separation of the components of lignocellulose, in which the belongs to the fields of high-value resource use 15 biomass is pretreated with irradiation and then coupled with low boiling point tetrahydrofuran or gamma- high boiling point valerolactone for a reaction, and a primary filtering is carried out in order to obtain a cellulosic component; tetrahydrofuran is recovered from the 20 filtrate obtained or a saturated NaCl solution is addition to the filtrate for the phase-separated precipitation of the lignin; and secondary filtration is carried out, the residue obtained is a lignin component, and the secondary filtrate is dried to obtain a component of 25 hemicellulose. Chinese Patent No. CN105385722 describes a method for dissolve and pre-process a lignocellulosic biomass through a mixed solvent made up of ionic liquid and gamma- valerolactone, which involves: firstly mixing with an ionic liquid and gamma-valerolactone of biomass lignocellulosic to form a pre-dissolution system and 5 pre-treatment, which is then heated in such a way that the components dissolve in solution. Then a antisolvent and dissolved lignocellulosic biomass precipitates and it regenerates; then the lignocellulosic biomass is collected, add a buffer solution, add cellulase and 10 xylanase for enzymolysis and a sugar solution is obtained. Part of the ionic liquid is replaced by the biological base gamma-valerolactone and a mixed system is formed. The same inventors have subjected lignocellulosic biomass from Cynara cardunculus L. (thistle) to a treatment process 15 in two stages to obtain fermentable glucose, in which in first stage the ground biomass is subjected to extraction and subjected to microwave-assisted cooking using a acidified mixture of gamma-valerolactone (GVL) up to obtain a solid cellulose paste, followed by a second 20th stage in which the pretreated material is hydrolyzed to glucose from cellulolytic enzymes. The first stage has been optimized analyzing the process temperature, the concentration of the acid catalyst and the GVL / water ratio. The process allows you to obtain a quantity of glucose equal to 30.17 g per 25 100 g of raw material (89% of the maximum theoretical yield) when the first stage is conducted at 150°C using a solution of acidified water (1.96% H SO m / m) (Gelosia M. et al., 2020, 2 4 Acid-Assisted Organosolv Pre-Treatment and Enzymatic Hydrolysis of Cynara cardunculus L. for Glucose Production, Energies, 13, 4195). The inventors themselves described an approach to increase 5 cellulose recovery, digestibility and delignification of the raw material from Cynara cardunculus L. The process involves a first stage in which the ground biomass is subjected to microwave-assisted extraction using a GVL / acidified water mixture to separate lignin and 10 hemicellulose from cellulose. In the second stage the pulp of cellulose is hydrolyzed by cellulolytic enzymes. In optimal conditions (154°C, 2.24% H SO and 0.62 ratio 2 4 GVL / water), the cellulose pulp has a content of cellulose of 87.59%, while the lignin content is 15 less than 8%. So the recovery and digestibility of the cellulose are equal to 79.46% and 86.94%, respectively. Approximately 40% of the initial hemicellulose is recovered as monosaccharides (Giannoni T. et al., 2021, Fractionation of Cynara cardunculus L. by Acidified Organosolv Treatment for the 20 Extraction of Highly Digestible Cellulose and Technical Lignin, Sustainability, 13, 8714). The inventors themselves described an organosolv stage which uses an acidified solution of gamma-valerolactone (GVL) / water to improve cellulose enrichment and 25 enzymatic saccharification of thistle stems (Cynara cardunculus L.). Under optimal conditions (140°C, 0.6 GVL / water and 2.24% HSO ), hemicellulose is efficiently removed from the 2 4 thistle, and up to 50% of its content is recovered in the aqueous fraction, while 86% of the cellulose is retained in the solid fraction. The resulting cardoon pulp has a cellulose content of 91.5% and enzymatic digestibility 5 of 100%. This results in an overall production of glucose of 37.17 g / per 100 g of raw material (90% maximum theoretical) using a high solids loading (20% m / m) and a high enzyme dosage (60 FPU / g cellulose). Instead, a low enzyme dosage, concentrations of were obtained 10 glucose of 169 g / l and 210 g / l using 10 FPU / g cellulose and 20 FPU / g of cellulose respectively (Fabbrizi G., 2022, High Solid and Low Cellulase Enzymatic Hydrolysis of Cardoon Stems Pretreated by Acidified gamma-Valerolactone / Water Solution, Energies 2022, 15, 2600). 15 The inventors themselves have disclosed that the residual biomass lignocellulosic is a significant source of high-quality carbohydrates industrial interest. However, the lignin content can limit the digestibility of cellulose and hemicellulose to simple sugars. So, there are pretreatments that 20 are intended to improve the digestibility of biomass lignocellulosic. The Organosolv process is an efficient fractionation process that allows obtaining a paste rich in cellulose (content greater than 90%) but with a quantity of lignin less than 5%. However, this process requires 25 significant amounts of solvent, making it uneconomical from economic point of view and high environmental impact. Therefore the solvent was separated by an addition process salt. In particular, the organic solvent gamma-valerolactone (GVL) in solution with water (60% m / m) was separated with NaCl or Na SO (XXIII CIRIAF NATIONAL CONGRESS Perugia, 13-14 2 4 April 2023, Fabbrizi G. et al., Evaluation of different 5 inorganic salts in Salting ‐out process of γ-valerolactone / water solutions, ISBN (online PDF) 978-88-9392-442-9 - © 2023 Morlacchi Editore University Press, CC BY 4.0 International. Published by Morlacchi Editore University Press). The inventors themselves carried out a chemical characterization 10 physics of lignocellulosic biomass residues from fruit production industries (Cavalaglio, Gianluca, et al. "Lignocellulosic Residues from Fruit Trees: Availability, Characterization, and Energetic Potential Valorization." Energies 17.11 (2024): 2611.). 15 Technical problem The valorization of products of industrial interest waste of ligno-cellulosic origin for obtaining cellulose. For this purpose it is necessary to separate the cellulose from the lignin to which it is interconnected, in the cell walls 20 of the plants. This solid structure prevents them from being attacked by microorganisms or in any case its specific valorization. They are you know several methods suitable for the purpose such as a pretreatment steam-mediated (steam-explosion) or liquid-mediated thermal (liquid-hot water) (chemical-physical methods), or other methods 25 which involve the use of fungi that secrete enzymes capable of to degrade the lignin structure, these methods (organic), even if they avoid the use of solvents, they require long processing times and large spaces for the process, are for this reason it is difficult to apply. Among the chemical methods that of extraction with organic solvent, the organosolv (OV) 5 is one of the most effective, because it is very efficient from the point of view of view of the purification of cellulose but at the same time expensive given the high quantity of solvent used, which makes the process uneconomical and high impact environmental. 10 The inventors themselves have already addressed the problem relating to the organosolv process and in the present invention they have verified that it is possible to recover the solvent at termination of the process by adding salt, for example with NaCl or NaSO . 2 4 15 In the present invention the same inventors have applied as they have already verified on a much larger scale going to design a complex procedure having the following distinctive features: • guarantees the obtaining of cellulose with a high degree of 20 purity; • allows the recovery and recycling of the solvent, in which it is significantly reduced the presence of impurities making it reusable in the same process similarly to a pure solvent; and • allows the recovery of other reagents by making them reusable in the same process, thus minimising re-injection into the system process of new solvents and reagents. 5 Object of the invention With reference to the attached claims, the problem technical is therefore solved by providing a procedure for the fractionation of lignocellulosic waste material which includes the following stages: 10 a) reduce a starting material into particles of dimensions not exceeding 2 cm, being said material starting material: lignocellulosic waste; b) subjecting said starting material as obtained to end of stage a) to an organosolv reaction 15 comprising a high-boiling polar organic solvent, water and an inorganic acid and / or base, until obtaining a first mix; c) separate said first mixture in such a way as to obtain a first liquid fraction comprising polar solvent 20 high boiling, water, lignin, hemicellulose and impurities, and a first solid fraction comprising cellulose pulp and solvent residues; d) subject said first solid fraction as obtained to end of stage c) at least one wash with water 25 and / or mixtures of high-boiling polar organic solvent and water until you get recycled cellulose pulp and a second liquid fraction containing water and residue high-boiling polar organic solvent; e) subject the first liquid fraction as obtained to the 5 end of stage c) to a separation reaction induced by inorganic salt (salting-out) so as to obtain two distinct liquid phases: a third liquid fraction comprising high-boiling polar organic solvent, lignin, water and inorganic salt, and a fourth fraction 10 liquid comprising water, inorganic salt, carbohydrates and high-boiling polar organic solvent; f) separate said third liquid fraction from said fourth liquid fractions as obtained at the end of stage e); g) dilute the third liquid fraction with water as 15 obtained at the end of stage f) in such a way as to obtain a fifth liquid fraction comprising solvent high-boiling polar organic matter, water, impurities and lignin; h) separate an eleventh liquid fraction from said lignin, wherein said eleventh liquid fraction is obtained 20 adding said second liquid fraction as obtained at the end of stage d) to the said fifth liquid fraction as obtained at the end of stage g); i) subject the eleventh liquid fraction obtained to the end of stage h) to a further reaction of 25 inorganic salt-induced separation (salting-out) in so as to obtain two further distinct liquid phases: one sixth liquid fraction comprising organic solvent polar high boiling, inorganic acid and / or base, water and impurities and a seventh liquid fraction comprising 5 water, inorganic salt and impurities; j) separate the sixth and seventh liquid fractions as obtained at the end of stage i); k) subject the fourth liquid fraction obtained to the end of stage f) and the seventh liquid fraction obtained at 10 end of stage j) to a basification reaction up to a basic pH so that the salt precipitates inorganic in crystalline form and recover it so that can be reused and even reintroduced into the stadium e) and / or at stage i) of the process; 15 said process wherein said sixth liquid fraction comprises the regenerated high-boiling polar organic solvent and can be reintroduced into stage b) in such a way as to obtain the said first mixture. The process described and claimed confers protection to 20 process products directly obtained from it. It constitutes a further object of the present invention high purity recycled cellulose obtained through the aforementioned process. Further features of the invention will become clear of the detailed description that follows with reference to the data experimental presented and the attached figures. Brief description of the drawings 5 Figure 1 shows in a flowchart the phases of the process of the preferred embodiment; and Figure 2 shows a portion of the flowchart according to a further preferred embodiment of the invention. Detailed description of the invention 10 Definitions In the context of the present invention for waste material of lignocellulosic biomass means waste derived from plant biomass composed mainly of cellulose, hemicellulose and lignin, from industry and 15 from agriculture. In the context of the present invention for organosolv reaction it means the solubilization reaction of lignin and hemicellulose, as first described in the patent US 3585104. 20 In the context of the present invention with reaction of salting-out is defined as the purification technique that exploits the reduced solubility of some molecules in a solution with very high ionic strength or to concentrate solutions. In the context of the present invention for organic solvent polar high boiling point means a solvent with a boiling point boiling between 150°C and 250°C, such as glycerol, ethylene glycol, GVL, dimethyl sulfoxide, 5 dimethylformamide. In the context of the present invention, for inorganic salt means a salt formed by ions with high electron density, such as sodium sulfate (NaSO), potassium nitrate 2 4 (KNO ), sodium chlorate (NaClO ), potassium chlorate (KClO ), 3 3 3 10 Magnesium sulfate (MgSO ). This invention is the subject of a process for the fractionation of waste material lignocellulosic which includes the following stages: a) reduce a starting material into particles of dimensions not exceeding 2 cm, being said material 15 starting lignocellulosic waste material; b) subjecting said starting material as obtained to end of stage a) to an organosolv reaction comprising a high-boiling polar organic solvent, water and an inorganic acid and / or base, up to 20 get a first mix; c) separate said first mixture in such a way as to obtain a first liquid fraction comprising polar solvent high boiling, water, lignin, hemicellulose and impurities, and a first solid fraction comprising pulp 25 cellulose and solvent residues; d) subject said first solid fraction as obtained to end of stage c) at least one wash with water and / or mixtures of high-boiling polar organic solvents and water until you get recycled cellulose pulp and 5 a second liquid fraction containing water and residue of high-boiling polar organic solvent; e) subject the first liquid fraction as obtained to the end of stage c) to a separation reaction induced by inorganic salt (salting-out) so as to 10 obtain two distinct liquid phases: a third fraction liquid containing polar organic solvent high boiling, lignin, water and inorganic salt, and a fourth liquid fraction comprising water, salt inorganic, carbohydrates and polar organic solvent 15 high boiling; f) separate said third liquid fraction from said fourth liquid fractions as obtained at the end of the stage And); g) dilute the third liquid fraction with water as 20 obtained at the end of stage f) in such a way as to obtain a fifth liquid fraction comprising high-boiling polar organic solvent, water, impurities and lignin; h) separate an eleventh liquid fraction from said 25 lignin, wherein said eleventh liquid fraction is obtained by adding said second liquid fraction as obtained at the end of stage d) to the said fifth liquid fraction as obtained at the end of the stage g); i) subject the eleventh liquid fraction obtained to the 5 end of stage h) to a further reaction of inorganic salt-induced separation (salting-out) in so as to obtain two further distinct liquid phases: a sixth liquid fraction comprising solvent high boiling polar organic, inorganic acid and / or base, 10 water and impurities and a seventh liquid fraction comprising water, inorganic salt and impurities; j) separate the sixth and seventh liquid fractions as obtained at the end of stage i); k) subject the fourth liquid fraction obtained to the 15 end of stage f) and the seventh liquid fraction obtained at the end of stage j) with a reaction of basification up to a basic pH so as to promote the precipitation of inorganic salt in crystalline form and recover it so that it can be reused and 20 also reintroduced into stage e) and / or stage i) of the process; said process wherein said sixth liquid fraction comprises the regenerated high-boiling polar organic solvent and can be reintroduced into stage b) in such a way as to obtain the said first 25 mix. Preferably, in stage b) the solvent is reintroduced regenerated high-boiling polar organic included in the said sixth liquid fraction as obtained at the end of stage j) and pure high-boiling polar organic solvent. 5 Advantageously, the regeneration of polar organic solvent high boiling allows it to be reused within the same process for fractionating wood waste material cellulosic object of the present invention, with a consequent savings on the costs of the procedure and a lower 10 environmental impact in terms of reduction of waste products discard the procedure. An additional advantage is given by the fact that the sixth fraction liquid, as well as comprising polar organic solvent high boiling, includes inorganic acid and / or base, in 15 this way you also save on the quantity of new acid and / or base to be introduced in stage b). Preferably, in stage d) the washes are one in number three. For example, stage d) includes the following stages: THE 20 d) subject said first solid fraction as obtained to end of stage c) to a first wash with mixtures of high boiling polar organic solvent and water up to obtain a second solid fraction and an eighth fraction liquid containing water, organic solvent residue 25 high boiling polar and lignin; II d) re-enter said eighth fraction at least once THE liquid as obtained at the end of stage d) for the THE first wash of stage d); III d) subject said second solid fraction as obtained THE 5 at the end of stage d) at least one second wash with water until a third solid fraction is obtained and said second liquid fraction containing water, residue of high-boiling polar organic solvent and lignin; IV d) subject said third solid fraction as obtained III 10 at the end of stage d) to a third wash with water until cellulose and a ninth liquid fraction are obtained containing water, traces of polar organic solvent high boiling point and traces of impurities; V d) re-enter said ninth fraction at least once IV 15 liquid as obtained at the end of stage d) for the IV washing of stage d). Preferably, this eighth liquid fraction is reintroduced THE in stage d) for at least three times, more preferably for five times. 20 Preferably, after being re-entered at least once THE in stage d), the eighth liquid fraction is introduced in stage e) in the form of a tenth liquid fraction as THE obtained at the end of stage d). Preferably, said ninth liquid fraction is reintroduced IV in stage d) for at least three times, more preferably for five times. IV Preferably, at the end of stage d), in addition to the pulp 5 of recovered cellulose a liquid fraction is obtained I unload. Preferably, this liquid waste fraction is fed into in stage h) together with the said second liquid fraction. Preferably, the high-boiling polar organic solvent is 10 selected from the group consisting of: γ-Valerolactone (GVL), glycerol, ethylene glycol, dimethyl sulfoxide, dimethylformamide. More preferably, the organic solvent high-boiling polar consists of γ-Valerolactone (GVL). Preferably, the inorganic salt is chosen from the group 15 consisting of: sodium sulfate (NaSO ), potassium nitrate 2 4 (KNO ), sodium chlorate (NaClO ), potassium chlorate (KClO ), 3 3 3 magnesium sulfate (MgSO ). More preferably, the inorganic salt consists of sulfate of sodium (NaSO). 2 4 20 Preferably, the inorganic acid is chosen from the group consisting of: sulfuric acid, hydrochloric acid, acid nitric. Preferably, the reduction of the size of the material starting is obtained by grinding. Preferably, these particles are between 0.5 mm and 2 mm. Preferably, step b) is carried out under stirring. Preferably, the organosolv reaction involves a step of 5 preheat to room temperature followed by a heat treatment at a temperature preferably between between 100°C and 250°C, more preferably between 140°C and 180°C for a time preferably between 5 minutes and 120 minutes minutes, most preferably between 30 minutes and 90 minutes. 10 Preferably in stages c), f) and h) the separation is conducted by filtration and / or vacuum filtration and / or filtration using a separating funnel. Preferably, a portion of the second liquid fraction as obtained at the end of stage d) is reintroduced at least 15 once in stage d). Preferably, said second liquid fraction is introduced at least three times, more preferably 5 times. Preferably, the separation of the third and fourth fractions liquid occurs at room temperature followed by filtering with 20 separatory funnel. Preferably, in stage e) and / or stage i) the salt inorganic, preferably NaSO is dissolved in water in a 2 4, saturation percentage between 10% and 100%, preferably between 60% and 100%. More preferably, in stage e) the inorganic salt, preferably NaSO is dissolved in water in a percentage 2 4, 70% saturation. More preferably, in stage i) the inorganic salt, 5 preferably NaSO is dissolved in water in a percentage 2 4, 100% saturation. Preferably, in stage e) and / or stage i) the salt inorganic, preferably NaSO is in crystalline form. 2 4, Preferably, basification is achieved by adding a 10 base to said fourth liquid fraction and to said seventh fraction liquid, the base being chosen from the group consisting of: NaOH, KOH, CaOH, MgOH. 2 2 Preferably, the basification reaction occurs at a temperature between 15°C and 40°C and the final pH after 15 addition of the base is preferably between 6 and 9. Preferably in stage h) the separation of lignin occurs through precipitation at room temperature followed by by vacuum filtration. A further object of the present invention is the 20 recycled cellulose pulp obtained through the process which includes the following stages: a) reduce a starting material of the ligno-type cellulose in particles of size not exceeding 2 cm, being said starting material material of 25 wood-cellulosic waste; b) subjecting said starting material as obtained to end of stage a) to an organosolv reaction comprising a high-boiling polar organic solvent, water and an inorganic acid and / or base, up to 5 get a first mix; c) separate said first mixture in such a way as to obtain a first liquid fraction comprising polar solvent high boiling, water, lignin, hemicellulose and impurities, and a first solid fraction comprising pulp 10 cellulose and solvent residues; d) subject said first solid fraction as obtained to end of stage c) at least one wash with water and / or mixtures of high-boiling polar organic solvents and water until you get recycled cellulose pulp and 15 a second liquid fraction containing water and residue of high-boiling polar organic solvent; said recycled cellulose pulp being characterised by an average percentage content of cellulose pulp on the total recovery of between 70% and 95% of cellulose, 20 preferably equal to 92.70% ± 3.80%, between 2% and 6% hemicellulose, preferably equal to 4.37% ± 0.22% and between 2% and 6% lignin, preferably equal to 3.29% ± 0.36% and a cellulose recovery compared to the cellulose initially present between 70% and 98%, 25 preferably equal to 93.34% ± 1.16%. The percentage contents of cellulose, hemicellulose and lignin make the recovered cellulose pulp thus obtained can be used effectively in energy generation processes or for use in the formulation of eco-friendly materials. 5 Example of embodiment of the invention The following embodiment refers to and is set forth in the attached figures. Stage a) involves grinding the starting material (Raw Material, RM) of ligno-cellulosic nature through a mill 10 knives to reduce the particle size (between 0.5 and 1mm) and increase the contact surface during the next stage b) which involves the reaction of organosolv. In the material starting point, the content of lignin, cellulose and hemicellulose is 19.55%, 38.76% and 13.53% respectively. 15 Stage b) involves subjecting 2.5 g of the RM as obtained at end of stage a) to an organosolvable reaction. In 2.5 g there are 0.49 g of lignin, 0.97 g of cellulose and 0.33 g of hemicellulose. To the 2.5 g of RM to be treated, 25 g of a 20 solution (1:10) containing 14.66 g of γ-Valerolactone (60% m / m), 9.77 g of water (37.76% m / m) and 0.57 g of sulfuric acid (2.24% m / m). The first mixture is then subjected to a heat treatment which consists of a first stage (pre- heating) which from 25°C brings the first mixture to the temperature of 25 140°C in 5 min. During the second stage (Steady State-heating) the mixture is kept at 140°C for 30 min. Finally, the third cooling stage brings the biomass back to temperature environment (25°C) in 10 min. The organosolv process occurs under constant agitation. 5 Stage c) involves separating the first mixture through a vacuum filtering obtaining 19.53 g of first fraction liquid consisting of 55.39% by mass of GVL (10.82g) to which the Most of the lignin in the RM remains bound. In this first liquid fraction also contains water, part of the acid 10 input, hemicellulose and impurities. After filtering, a first solid fraction is obtained called cellulose pulp (CP), this first fraction solid part of the first mixture remains bound; in fact, as described below, the first solid fraction is washed with I III IV 15 three separate washes (stage d ), d ), d )) to maximize the solvent recovery and increase biomass purity treated. THE The first wash (stage d)) requires that the first fraction solid is then washed with 25 g of a solution containing 20 15 g of water and 10 g of GVL in order to obtain a second solid fraction and an eighth liquid fraction. This eighth liquid fraction is recovered after washing the CP and is used for five subsequent first wash cycles (stage II d )), in which it is enriched with lignin (0.11g of lignin at 25 each wash cycle). It will be appreciated that at the end of the five cycles called eighth liquid fraction, in the form of tenth liquid fraction, will then be treated in stage e) and subsequent stages for the precipitation of lignin and the recovery of the GVL. It will be appreciated that, when the eighth fraction liquid is reused for at least one subsequent first cycle 5 washing is called the tenth liquid fraction. The second III washing (stage d)) provides that the second solid fraction be further washed with 20 ml of water at room temperature environment in order to remove traces of solvent and maximize GVL recovery, obtaining a third fraction 10 solid and a second liquid fraction. The 20 ml of the second liquid fraction containing water, residual GVL (3.07g) and part of the lignin are recovered. In the second liquid fraction the ratio between the GVL present and the water introduced (20ml) is targeted to obtain an ideal ratio for precipitation 15 of lignin. III It will be appreciated that at the end of stage d) the second liquid fraction will then be treated in stage h) where lignin residues will be separated and then purified in stage i), in the form of an eleventh liquid fraction, which 20 involves a salting-out reaction and regeneration of the solvent The third solid fraction is subjected to a third wash IV in stage d) with 100 ml of water, obtaining cellulose and a ninth liquid fraction which after filtering will be used in V 25 subsequent third washings (stage d). The ninth liquid fraction contains, after the third washing cycle of the third fraction solid, comprising CP cellulose pulp, 0.3g GVL and traces of impurities and is therefore usable for numerous third parties CP washings. I III IV At the end of the three washes (stage d ), d ), d )) we obtain 0.93g of recycled cellulose pulp consisting of 0.86g of 5 cellulose and 0.03g of lignin. The process carried out so far and thus optimised it allows an average recovery of 90.44% m / m of the cellulose initially present in the RM at a purity of 92.34% and is therefore an excellent raw material to be used in energy generation or use processes in 10 formulation of eco-friendly materials. Furthermore, the procedure provides for the first fraction to be submitted liquid to the salting-out reaction, heating it to 34°C and adding 1.74 g of NaSO (Sodium Sulfate) in the form 2 4 crystalline (230g per litre of water present in the solution, 15 70% of saturation). Once the salt is dissolved below stirring, the solution divides into a third liquid fraction and in a fourth liquid fraction well distinct due to the effect of the salting-out. The fourth liquid fraction of mass 7.28 g and the third liquid fraction of mass 13 g. The fourth liquid fraction 20 contains water, NaSO, residual carbohydrates and 0.18 g of GVL. The third 2 4 liquid fraction contains 10.09 g of GVL, the extracted lignin from the RM, part of water with a small percentage dissolved of salt. The two fractions are separated in stage f) with a separating funnel. 25 In order to allow a precipitation and a removal of lignin from the third liquid fraction (13g) (stage g)) 91 g of water are added at a temperature of 23°C in order to obtain a third liquid fraction:water ratio of 1:7. ratio is optimal to allow with the least amount possible high lignin recovery of water. The ratio 5 furthermore, it allows not to disperse the lignin on the edges of a container, behavior observed with ratios even slightly lower than 1:7, in this way you get a fifth liquid fraction. Once the fifth fraction is obtained liquid fraction, 20 ml of second liquid fraction are added III 10 (described in stage d) obtaining the eleventh fraction liquid containing lignin. The precipitation process of the lignin in the said eleventh liquid fraction occurs at temperature of 23°C and lasts for eight hours at the end of the which are then filtered (stage h)). 15 Following the precipitation of the lignin called eleventh liquid fraction is filtered under vacuum to be separated from precipitated lignin (stage h). The filter has pores from 1µm which do not allow the passage of lignin particles. 0.21g of lignin is collected, this can be used 20 in various processes, from the most classic (thermal conversion) to the most innovative (nanoparticles, cosmetics). The eleventh fraction liquid coming out of the filter contains GVL, the added water in stage g) and impurities. In stage i) the eleventh liquid fraction is brought to 34°C and 25 To this is added 46.5g of NaSO (saturation based on 2 4 weight of water contained in the eleventh liquid fraction. Thanks to the salting-out effect, two phases are obtained: seventh aqueous liquid fraction below and a sixth liquid, organic and GVL-rich fraction above. The two liquid fractions are separated in stage k) with a funnel separator. The seventh liquid fraction has a weight of 157.5g and 5 a pH of 3.5. The sixth liquid fraction constitutes the solvent recovered and regenerated, has a total weight of 13.07 g of which 11.05 g of GVL, 1.8 g of impurities and 0.218 g of sulfuric acid. The sixth liquid fraction as obtained at the end of the stage j) is reintroduced into stage b), in particular it is 10 used for the preparation of the first mixture. Given the yield of process recovery (77.9%) of the initial GVL mass is It is necessary to insert approximately 23% pure solvent at each cycle. As regards the composition of the sixth fraction liquid, the presence of 0.218 g of sulfuric acid allows a 15 savings of this compound of about 38%, will therefore be just add 0.352 g of sulfuric acid in the following stages b). The sixth liquid fraction contains a part of impurity (1.8g) which remains stable during treatments subsequent purification, for this reason it does not constitute a 20 problem and its effect on the organosolv reaction After the third liquid fraction and the fourth liquid fraction they are separated in stage f), the fourth liquid fraction together with the seventh liquid fraction as obtained at the end 25 of stage i) are subjected to a reaction of basification (stage k)). In particular, the fourth fraction liquid (7.28g), as obtained at the end of stage f), contains water, NaSO , residual sugars and a small part of 2 4 solvent. In particular, its sugar content is approximately 0.88g (2.7% m / m) while as regards salt, it contains 1.74g of dissolved NaSO. The solution is alkaline-forming by 2 4 5 use NaOH until pH 6 is reached. Bringing the solution temperature at 20°C, precipitation occurs of the salt in non-anhydrous crystalline form. The separation of the portion of salt allows an immediate recovery of 78.52% in mass of salt with a humidity of 57.22%. The aqueous phase 10 separate contains a concentration of 150g / L of NaSO and can 2 4 be subjected to osmosis processes for optimal recovery of the salt. Advantageously, process cycles are able to ensure a constant composition of the output biomass 15 from the process. The recycling of polar organic solvents high boiling allows for significant savings in the GVL input making this process sustainable both from the point of view environmental, as well as economic. It will be appreciated that by repeating the process does not accumulate impurities in the sixth fraction 20 liquid, a distinctive feature of the process. Furthermore, the choice of salt used, NaSO is of crucial importance. 2 4 In most cases it constitutes a waste industrial, does not present toxicity and the proximity of the temperatures of maximum saturation and crystallization play a role 25 a fundamental role in its recovery and reuse in the procedure described. The process described and claimed provides protection to process products directly obtained from it. Examples Materials and Methods: Cynara cardunculus L. was used. 5 (var. altilis DC). Leaves and flowers have been removed. manually, the stems were chipped and then ground to a final grain size ≤1 mm to perform the treatment organosolv. To perform lignocellulosic characterization the biomass and cellulose pulp (CP) were ground 10 until obtaining a grain size of 0.5 mm by sieving. The concentrations of monosaccharides were analyzed by HPLC. The solvents used were GVL (Sigma- Aldrich, Saint Louis, MO, USA) and H O. Phase extraction is was performed using the anhydrous salt NaSO (Sigma-Aldrich, 2 4 15 Saint Louis, MO, USA). Treatment parameters were kept constant, based on optimal conditions identified in Fabbrizi et al. A solution was prepared acidified (m / m), containing 58.7% GVL, 39.1% H2O (stage b)). In each treatment, 2.5 g of thistle were used 20 and 25 g of the acidified solution. The treatment time and cooling was 30 and 10 minutes respectively. After the microwave-assisted fractionation process, the The contents of the container were vacuum-filtered using a Büchner funnel to separate the first solid fraction of CP 25 from the acidic GVL / water solution (first liquid fraction). The first liquid fraction was collected and quantified. The first solid fraction was subjected to a series of washes (stage d)). All three liquids obtained from the various washings and filtrations (second liquid fraction, eighth liquid fraction e ninth liquid fraction) were weighed and analyzed for evaluate the GVL and the monosaccharide content. Also the 5 solid fraction resulting from washing processes (pulp (recovered cellulose) was quantified and characterized. of particular interest is the washing with just water which is III IV carried out in 2 different stages (d ) and d )) using different III amount of water. The second wash (stage d) was 10 performed with 25 mL of water and produced the second fraction IV liquid. The third wash (stage d)) was carried out using 100 mL of H 0. Washing with water was carried out in 2 different stages has proven to be very advantageous since, despite a large portion of the GVL being removed in the second 15 washing, in the third solid fraction some GVL remains which is recovered with the third wash, increasing the recovery of the GVL. Furthermore, the second liquid fraction obtained can be combined and processed together with the fifth liquid fraction since 20 has a similar GVL concentration. The first liquid fraction, the eighth liquid fraction and the second liquid fraction are subjected to three different treatments for the recovery and regeneration of the GVL. The first liquid fraction was collected, weighed and was 25 a first liquid-liquid extraction was carried out via the addition of NaSO to 70% saturation (salting-out). 2 4 Salt dissolution was carried out at 33°C. After the dissolution is completed, the stirring is was interrupted and two separate liquid phases were formed, 5 respectively the third liquid fraction and the fourth fraction liquid; the latter being rich in sugars, and the third liquid fraction being rich in GVL and lignin. The separation was performed through a separatory funnel and the third and fourth liquid fraction were weighed, the fourth fraction 10 liquid was analyzed by high-pressure liquid chromatography performance (HPLC) to determine the content of monosaccharides. The third liquid fraction was subjected to the stage g) and h) to allow the precipitation of lignin to regenerate GVL. In stage g) HO was added in a 15 ratio 1:7 GVL:HO (m / m) under continuous stirring and in stir for 30 minutes to ensure maximum precipitation of lignin. To the fifth liquid fraction as obtained at end of stage g) the second fraction was added liquid as obtained at the end of stage d) obtaining 20 the eleventh liquid fraction which has been subjected to a filtration process in stage h) to remove lignin precipitated. Filtration was carried out with a flask vacuum on a calibrated ceramic crucible. The precipitated lignin The resulting product was dried at 30°C overnight and then weighed. 25 The eleventh liquid fraction was weighed and then subjected liquid-liquid extraction by adding NaSO to the 2 4 100% saturation in a continuously stirred flask 33°C (stage i)). After the salt was dissolved, a separatory funnel. The separation phase (stage k)) was performed at 33°C to avoid salt precipitation. at the end of stage k) two products have been obtained, the seventh 5 liquid fraction of salt water with traces of monosaccharides and GVL, and the sixth liquid fraction containing recovered GVL and regenerated, reddish in color, which was weighed and sampled to monitor the concentration of GVL by HPLC. The eighth liquid fraction obtained after the first washing of the 10 The first solid fraction was collected and weighed. The same eighth fraction was used 6 times in the stadium (stadium THE d ) for 6 different organosolv processes (stage b)). After use repeated, the eighth liquid fraction, in the form of a tenth liquid fraction, was subjected to stage e) and to 15 successive stages for lignin precipitation and the recovery of the GVL, and then the GVL was reused as GVL / water washing solution. The 25 ml of the second liquid fraction were combined with the fifth liquid fraction. 20 The fifth liquid fraction was obtained as follows: after the separation between the fourth liquid fraction and the third fraction liquid, made in stage f), the third liquid fraction is was collected and weighed. Being composed mainly of water, precipitated lignin may be visible, but for 25 to ensure the precipitation of lignin, in stage g), are 10 mL of H2O were added while stirring, obtaining the fifth liquid fraction. The fifth and second liquid fractions are were respectively subjected to stage h) which provides for a filtration phase in a vacuum flask with a ceramic crucible calibrated to recover the lignin. The precipitated lignin 5 recovered was dried at 30°C overnight and then weighed. At this point, the eleventh liquid fraction as obtained at the end of stage h), was subjected to the stage i) of salting-out and a sixth was obtained liquid fraction and a seventh liquid fraction which have been 10 subjected to liquid-liquid separation by the addition of NaSO at 100% saturation in a stirred flask 2 4 continues at 33°C. After the salt has dissolved it was used a separatory funnel (stage j)). The stage of separation was performed at 33°C to avoid the 15 precipitation of salt. At the end of stage j) there are two products were obtained, the seventh liquid fraction containing salt water with traces of monosaccharides and GVL, and the sixth liquid fraction containing recovered and regenerated GVL reddish color (RED GVL), the sixth liquid fraction was 20 weighed and sampled to check the GVL concentration via HPLC and subsequently used to start a new organosolv treatment (stage b)). All characterizations of recycled cellulose pulp (RCP) were conducted in triplicate following NREL procedures. 25 The RCP has been characterised in terms of its content of cellulose, hemicellulose and lignin. Table 1 shows the lignocellulosic characterization of the thistle stems. The organosolv process was performed 7 times, the first time using pure reagents, the next 6 times using RED 5 GVL and additional pure GVL content to meet the parameters organosolv. Table 1 Sample Cellulose (%) Hemicellulose (%) Lignin (%) Other (%) A 45.23 14.85 19.54 20.37 B 40.57 12.41 19.23 27.79 C 43.40 13.33 19.88 23.39 Mean 43.07±1.92 13.53±1.01 19.55±0.26 28.16±3.04 To verify the consistency of performance, the RCP was characterized in terms of cellulose content, 10 hemicellulose and lignin. The data are reported in Table 2, an average value measured for the three components of 92.34±1.16%, 4.37±0.22% and 3.29±0.30% respectively for cellulose, hemicellulose and lignin. The low standard deviation evaluates the persistent effectiveness of the delignification process with RED 15 GVL. The performance of the organosolv process was also maintained in terms of cellulose recovery (CR) and recovery of solids. On average, a solid recovery of 39.42±1.63 g / 100 g RM and a CR of 93.70±3.80 g cellulose after OV / 100 g cellulose first OV. Complete data are reported 20 in table 3. Table 2 Sample Cellulose (%) Hemicellulose (%) Lignin (%) Pure GVL 91.72±3.69 4.45±0.87 3.83±0.85 I recirculation 90.70±0.20 4.68±0.02 4.62±0.24 II recirculation 92.45±0.10 4.22±0.03 3.33±0.18 III recirculation 92.66±0.65 4.41±0.04 2.93±0.34 IV recirculation 92.10±2.21 4.56±0.27 3.34±0.15 V recirculation 93.19±0.48 4.03±0.03 2.78±0.26 VI recirculation 93.53±0.79 4.26±0.26 2.21±0.09 Mean 92.34±1.16 4.37±0.22 3.29±0.30 Table 3 Sample Solids recovered (%) CR (%) Pure GVL 40.02±1.34 94.71±3.18 I recirculation 38.88±1.28 90.99±3.00 II recirculation 39.26±0.80 93.63±1.90 III recirculation 40.18±2.44 96.06±5.83 IV recirculation 40.08±1.46 96.19±3.48 V recirculation 38.60±0.82 92.27±1.43 VI recirculation 38.22±1.20 91.52±2.18 Average 39.42±1.63 93.70±3.80 Different amounts of GVL were used in the different tests. pure with an average addition of 26.76% (m / m) per test. A 5 larger and unexpected amount of RED GVL was recovered at end of the third reuse and, consequently, a quantity lower pure GVL was added to the fourth reuse. Table 4 Pure GVL Sample (% m / m) Pure GVL 100.00 I recirculate 26.15 II recirculation 29.73 III recirculation 35.83 IV recirculation 9.99 V recirculation 28.74 VI recirculation 09.30 Average 26.76 This data was considered part of an operational error. in RED GVL weight measurement. Complete data is reported in table 4. 5 It appears that the lignin removed from the second liquid fraction and from the fifth liquid fraction in stage i) of regeneration and of the lignin contained in the RCP is on average equal to 69.19±9.73% of the total amount of incoming lignin. The lignin was also precipitated from the eighth fraction after six reuses; 10 so, it was not possible to assign this correctly value at each use, but the average result is 3.42±15.3% for use. The data are reported in Table 5. The RED GVL was analyzed in terms of GVL content for determine the recovery of GVL. As expected, the recovery of 15 highest mass was obtained from the fifth fraction liquid. However, a further recovery of GVL from the second fraction liquidity has allowed on average the recovery of further 2.78±0.75 g. Data on the recovered quantity are reported in table 6. 5 Table 5 Sample Lignin in Lignin Lignin Lignin Lignin Lignin Input (mg) in CPR II found found V fraction (mg) fraction (mg) (%) liquid liquid (mg) (mg) Pure GVL 488.9±0.5 38.3±1.3 214.7±12.6 10.3±0.6 263.4±11.8 53.86±2.46 I recirculation 488.5±0.3 44.9±1.5 316.7±53.1 11.3±7.7 372.9±43.9 76.34±9.04 II recirculation 490.2±1.6 32.8±0.8 295.3±0.1 3.0±2.6 331.0±1.9 67.53±0.60 III recirculation 489.9±0.6 29.5±1.8 287.7±3.7 16.6±1.2 333.9±11.0 68.16±1.98 IV recirculation 495.3±5.8 34.2±0.8 354.0±29.0 12.9±2.4 401.1±25.8 80.94±4.25 V recirculation 490.7±0.3 30.3±3.9 315.4±20.2 12.2±1.9 356.7±19.3 72.70±3.90 VI recirculation 490.0±0.4 27.3±6.9 323.0±27.8 5.8±4.5 355.0±17.6 72.46±3.65 Mean 490.4±3.0 34.2±6.3 295.2±51.6 10.3±7.0 339.4±48.8 69.19±9.73 The GVL content in both liquid fractions remains constant through various cycles of regeneration and reuse, indicating that no impurities have accumulated over time significant. The average concentration obtained, evaluated over 60% of the GVL, demonstrates the suitability of these GVL / HO solutions as input for subsequent organosolv treatment, without the need for other phases of concentration, such as for example 5 by distillation. An evaporation test was performed on the RED GVL to check if the impurities were constant in weight and an average amount of 23.7±1.1 mg of was found impurities per gram of RED GVL. Table 6 Sample GVL in RED GVL in RED GVL GVL in RED GVL GVL in RED GVL GVL II Fraction (g) II Fraction (% V Fraction (% m / m) V Fraction m / m) (g) Pure GVL 8.03 ± 0.29 2.80 ± 0.16 81.83 ± 1.45 85.14 ± 0.60 Recirculation 8.25 ± 0.67 2.04 ± 0.22 82.00 ± 0.60 80.66 ± 1.19 II recirculation 8.39 ± 0.47 1.68 ± 0.17 73.28 ± 0.12 84.80 ± 0.22 III recirculation 8.60 ± 0.32 5.30 ± 2.52 76.95 ± 2.26 83.50 ± 0.96 IV recirculation 7.96 ± 0.29 2.74 ± 1.32 69.25 ± 3.21 67.23 ± 1.89 V recirculation 9.98 ± 0.27 3.49 ± 0.73 81.35 ± 0.20 73.30 ± 0.73 VI recirculation 9.25 ± 0.29 1.42 ± 0.15 77.91 ± 0.60 75.93 ± 0.15 Mean 8.64 ± 1.21 2.78 ± 0.75 77.51 ± 1.51 78.65 ± 0.82 These impurities could be attributed to lignin residues, NaSO and other smaller compounds soluble in the GVL or 2 4 in the residual H O, which gives RED GVL its reddish color. Finally, considering the initial mass of GVL used for 5 initiate each procedure for the fractionation of material of lignocellulosic waste, the total GVL was estimated recovered. With some peaks above 90%, it was obtained an average recovery of 77.90±7.67%. Furthermore, in other studies it is It has been demonstrated that the combination of precipitation of the 10 lignin and vacuum distillation gave a 90% recovery of the GVL by forming a sticky residue, which was the GVL trapped together with the remaining lignin. Furthermore, in the extraction with liquid CO it was possible to recover up to 87% of the GVL in the extract, while approximately 10% of the GVL 15 remained in the refined, because the mass exchange was limited due to the lack of an effective mechanism of mixing. Although these techniques have achieved a slightly higher percentage in the recovery of the GVL, the costs energy and plant costs are definitely more important. The data 20 on GVL recovery and recovered GVL mass are shown in Table 7. It will be appreciated that the term recirculation, used in the tables 2 to 7, is considered a synonym of the term reuse, used in the text. Table 7 Regenerated GVL Sample (g) Regenerated GVL (%) Pure GVL 10.82±0.45 73.85±3.05 I recirculation 10.30±0.89 70.27±6.08 II recirculation 10.07±0.64 68.68±4.38 III recirculation 13.90±2.84 94.84±19.37 IV recirculation 10.70±1.61 72.99±11.00 V recirculation 13.47±0.27 91.93±6.82 VI recirculation 10.67±0.29 72.78±3.00 Average 11.42±0.99 77.90±7.67

Claims

CLAIMS 1. Process for the fractionation of lignocellulosic waste material comprising the following steps: a) reducing a starting material into particles of size not exceeding 2 cm, said starting material being lignocellulosic waste material; b) subjecting said starting material as obtained at the end of step a) to an organosolv reaction comprising a polar high-boiling organic solvent, water and an inorganic acid and / or base, until a first mixture is obtained; c) separating said first mixture in such a way as to obtain a first liquid fraction comprising polar high-boiling solvent, water, lignin, hemicellulose and impurities, and a first solid fraction comprising cellulose pulp and solvent residues;d) subjecting said first solid fraction as obtained at the end of step c) to at least one wash with water and / or mixtures of polar high-boiling organic solvent and water until recovered cellulose pulp is obtained and a second liquid fraction containing water and residue of polar high-boiling organic solvent; e) subjecting the first liquid fraction as obtained at the end of step c) to a salt-induced separation reaction (salting-out) in the presence of inorganic salt so as to obtain two distinct liquid phases: a third liquid fraction comprising polar high-boiling organic solvent, lignin, water and inorganic salt, and a fourth liquid fraction comprising inorganic salt, carbohydrates, polar high-boiling organic solvent and water; f) separating said third liquid fraction from said fourth liquid fraction as obtained at the end of step e);g) diluting with water said third liquid fraction as obtained at the end of step f) so as to obtain a fifth liquid fraction comprising high-boiling polar organic solvent, water, impurities and lignin; h) separating an eleventh liquid fraction from said lignin, wherein said eleventh liquid fraction is obtained by adding said second liquid fraction as obtained at the end of step d) to said fifth liquid fraction as obtained at the end of step g); RBI18766-IT i) subjecting the eleventh liquid fraction obtained at the end of step h) to a further separation reaction induced by inorganic salt (salting-out) so as to obtain two further distinct liquid phases: a sixth liquid fraction comprising high-boiling polar organic solvent, inorganic acid and / or base, water and impurities and a seventh liquid fraction comprising water, inorganic salt and impurities;j) separating the sixth and seventh liquid fractions as obtained at the end of step i); k) subjecting the fourth liquid fraction obtained at the end of step f) and the seventh liquid fraction obtained at the end of step j) to a basification reaction up to a basic pH so as to precipitate the inorganic salt in crystalline form and recover it so that it can be reused and also reintroduced into step e) and / or into step i) of the process; said process in which said sixth liquid fraction as obtained at the end of step j) comprises the regenerated high-boiling polar organic solvent can be reintroduced into step b) so as to obtain said first mixture.; 2. Process according to claim 1, wherein the yield of the recovered and regenerated high-boiling polar organic solvent is between 60% and 90%, preferably 77.9% of the mass of the initial high-boiling polar organic solvent.

3. Process according to claim 1 or 2 wherein the yield of recovered lignin is between 30% and 60%, preferably 43.7% of the initial lignin mass.

4. Process according to any of the preceding claims, wherein the yield of recovered inorganic salt is between 60% and 85%, preferably 78.52% of the initial salt mass.

5. Process according to any of the preceding claims, wherein the yield of recovered cellulose is between 70% and 95%, preferably 93.70% of the initial cellulose mass.

6. Process according to claim 5 wherein the recovered cellulose has a purity of between 80% and 95%, preferably 92.34%.

7. Process according to any of the preceding claims, wherein in step b) the regenerated high-boiling polar organic solvent included in said sixth liquid fraction as obtained at the end of step j) and pure high-boiling polar organic solvent are reintroduced. RBI18766-IT 8. Process according to any of the preceding claims wherein in step d) the washes are from one to three in number.

9. Process according to claim 8 wherein said step d) comprises the following steps: dI) subjecting said first solid fraction as obtained at the end of step c) to at least one first wash with mixtures of high-boiling polar organic solvent and water until a second solid fraction and an eighth liquid fraction containing water, residue of high-boiling polar organic solvent and lignin are obtained; dII) reintroducing said eighth liquid fraction as obtained at the end of step dI) at least once for the at least one first wash of step dI); dIII) subjecting said second solid fraction as obtained at the end of step dI) to at least one second wash with water until a third solid fraction and a second liquid fraction containing water, residue of high-boiling polar organic solvent and lignin are obtained;dIV) subject said third solid fraction as obtained at the end of stage dIII) to at least a third wash with water until recovered cellulose pulp is obtained and a ninth liquid fraction containing water, high-boiling polar organic solvent residue and impurities; dV) reintroduce said ninth liquid fraction as obtained at the end of stage dIV) at least once for at least a third wash of stage dIV).

10. Process according to any of the preceding claims wherein in step b) the high-boiling polar organic solvent is selected from the group consisting of: γ-Valerolactone (GVL), glycerol, ethylene glycol, dimethyl sulfoxide, dimethylformamide.

11. Process according to any of the preceding claims wherein in step b) the inorganic acid is selected from the group consisting of: sulfuric acid, hydrochloric acid, nitric acid.

12. Process according to any of the preceding claims wherein in steps e) and i) the inorganic salt is selected from the group consisting of: sodium sulphate (Na2SO4), potassium nitrate (KNO3), sodium chlorate (NaClO3), potassium chlorate (KClOj), magnesium sulphate (MgSO4) 13. Recycled cellulose pulp obtained by a process comprising the following steps: RBI18766-IT a) reducing a starting material into particles no larger than 2 cm in size, said starting material being lignocellulosic waste material; b) subjecting said starting material as obtained at the end of step a) to an organosolv reaction comprising a high-boiling polar organic solvent, water and an inorganic acid and / or base, until a first mixture is obtained; c) separating said first mixture in such a way as to obtain a first liquid fraction comprising high-boiling polar solvent, water, lignin, hemicellulose and impurities, and a first solid fraction comprising cellulose pulp and solvent residues;d) subjecting said first solid fraction as obtained at the end of stage c) to at least one wash with water and / or mixtures of high-boiling polar organic solvent and water until recovered cellulose pulp is obtained and a second liquid fraction containing water and residue of high-boiling polar organic solvent; said recovered cellulose pulp being characterised by an average percentage content of the total recovered cellulose pulp of between 70% and 95% of cellulose, preferably equal to 92.70% ± 3.80, of between 2% and 6% of hemicellulose, preferably equal to 4.37% ± 0.22% and of between 2% and 6% of lignin, preferably equal to 3.29% ± 0.36% and a recovery of RBI18766-IT cellulose with respect to that initially present of between 70% and 98%, preferably equal to 92.34% ± 1.16%.