MILL STREAMS"

Technical Domain of the Invention

The present invention relates the isolation of ellagic acid from streams of the lignocellulosic materials processing industries, preferably in streams of cellulosic pulp mills, which may have applications in several areas, such as chemical technology and health .

Ellagic acid, along with other components, is found dissolved in cooking liquors and bleaching effluents during the chemical processing of wood into pulp. Due to its polyphenolic and polyaromatic character, ellagic acid is a substance with unique chemical and bioactive properties, known for its antioxidant and chelating activities, attracting growing interest for technical and biomedical applications (e.g., possible antibacterial, antifungal, antiviral, anti-inflammatory, hepato- cardioprotective, chemopreventive, anti-neurodegenerative, antiasthmatic, anti-diabetic, gastroprotective and properties similar to antidepressants, among others) .

Summary of the invention

The present invention relates to a method for the recovery of ellagic acid from industrial streams of cellulosic pulp mills, or streams from other lignocellulosic materials processing industries, comprising the following steps: a) Collecting a stream effluent and adjusting its pH between 0.1 and 14, and temperature between 1 and 100°C for subsequent conditioning; b) Conditioning of the effluent for a time between 0.1 and 720 hours in a container having a surface area-to-volume ratio between 0.1 and 100 irT ¹ and made of a material selected from metal derivatives, glass, or plastics, which are suitable for the crystallization of ellagic acid, wherein the effluent is conditioned at the pH and temperature adj usted in the previous step; c ) Separation of the ellagic acid-containing precipitate obtained in the previous step via crystallization, wherein the separation is carried out by centrifugation or any other separation technique suitable for the purpose ; d ) Successive washing of the separated ellagic acid-containing precipitate with water and separation of the precipitate by centrifugation or any other separation technique suitable for the purpose ; e ) Drying the obtained ellagic acid product .

In one embodiment , the industrial stream is an effluent from acid sulphite processes , such as cooking liquors or bleaching line effluents .

In one embodiment , step a ) is carried out after removing nonprocessed suspended matter .

In one embodiment , step b ) is carried out at conditioning temperatures between 60 and 80 ° C when the effluent is cooking liquor .

In one embodiment , step b ) is carried out at conditioning temperatures between 20 and 40 °C when the effluent is an alkaline bleaching effluent .

In one embodiment , the pH of the effluent in step a ) is adj usted between 2 and 5 .

In one embodiment , the conditioning time is above 720 hours .

In one embodiment , the container is made of glass with a percentage of borosilicate , between 65 and 80% of silica and between 8 and 25% of boron trioxide .

In one embodiment , the container is made of plastic such as polyethylene terephthalate or high-density polyethylene . In one embodiment, the container is made of metal derivatives, such as variants of stainless steel.

In one embodiment, the surface area-to-volute ratio is above 100 nt ¹

In one embodiment, step d) is carried out using acidified water comprising HC1 between 0.1 and 20% v/v.

Background of the invention and state of the art

Ellagic acid (EA) (Figure 1) belongs to the class of extractable polyphenols (tannins) widely distributed among dicotyledonous species (Quideau and Feldman, 1996) . In plants, EA is mostly found in the composition of so-called hydrolysable tannins, where EA is esterified to sugars, resulting in a wide variety of structures also known as ellagitannins (ETs) . Like other tannins, ETs are secondary metabolites of higher plants and act as part of the defence mechanism against microbial and animal attacks due to their astringent capacity and ability to form complexes with proteins and polysaccharides (Quideau and Feldman, 1996) . Hydrolysable tannins have long been known for their use in leather tanning processes (Quideau and Feldman, 1996) . However, currently, the growing interest in these compounds is mainly associated with the consumption and development of new products with benefits for human health, linked to the antioxidant properties of phenolics (Wu et al., 2004) . In fact, due to the mitigating and/or preventive effects in several chronic diseases linked to oxidative stress, including cancer, cardiovascular diseases and neurodegenerative pathologies, EA has been the subject of several scientific studies (Al-Sayed and El-Naga, 2015; Nguyen et al. , 2017) . In addition to food and biomedical applications, EA and ETs may also have applications linked to advanced materials, such as polymeric materials (Reitze et al., 2001) , chelating reagents (Przewloka and Shearer, 2002) , ion exchange resins (Zhang and Chen, 1988) , materials for electrochemical devices (Goriparti et al. , 2013) , among others. Marketed EA products are produced essentially from natural plants, fruits and agricultural residues, since the organic synthesis results in low yields and can compromise the biological activity of EA due to failures in the chemoselectivity, regioselectivity and stereoselectivity of the process (Quideau and Feldman, 1996) .

Thus, several methods have been registered to produce EA, such as: tara (CN107827900A) , pomegranate peel (CN1803801A) , mango seed (CN107163059A) , blackberry branches and leaves (CN106913639A) , flower galls (CN105175427A) , raspberry (KR20170135744A) , eucalypt leaves (CN105132179A) and many other natural sources (Koponen et al. , 2007; Okuda et al. , 2009) .

Examples of known methods of producing EA include oxidative synthesis from ETs containing gallic acid and its water-soluble esters (US5231193A; EP0390107A2) or by a combination of alkaline hydrolysis and oxidation (CN105753880A) .

At the same time, EA, methyl derivatives of EA and glycosides of both form part of the tannin extracts of Eucalyptus , Quercus , Acacia and Castanea species, among other angiosperms (Fengel and Wegener, 1989) . Since these woods are used in cooking processes to produce cellulosic pulp, they can also be considered a great source of EA. In fact, EA is present in different industrial streams from the production of kraft pulps (Costa et al., 2014) and sulphite pulps (Rodrigues et al. , 2018) . It should be noted that, despite the pulp sector being a prospective source of EA derivatives, no viable solutions have so far been proposed for their recovery from industrial effluents. There are few publications that aim to isolate the EA from the eucalypt wood acid sulphite cooking liquor (Llano et al. , 2015; Alexandri et al. , 2016) .

Mostly, EA and its derivatives are obtained by extraction with a certain organic solvent, with mixtures of organic solvents (Quideau and Feldman, 1996) , with mixtures of organic solvents with water or, more recently, using ionic liquids (IL) (Chowdhury et al. , 2010) . As for the industrial streams in the pulp and paper industry, EA recovery approaches are limited to extraction with poorly water-mixable organic solvents such as ethyl acetate (Alexandri et al. , 2016) or ethyl ether (Llano et al. , 2015) . Purification of EA is normally carried out by multi-step processes and may involve chromatographic and recrystallization steps, among other separation techniques.

It should be noted that despite the aforementioned approaches in the production and isolation of EA, conventional extraction methods are not very selective, being affected by the great diversity of ET structures, a wide variety of plant sources and difficult purification, leading to low yields of EA, contaminations and excessive costs. Consequently, the need arises to develop alternative technologies, more efficient in terms of yield and energy cost and less polluting, to produce EA of superior purity and on a large scale, ideally from sources that do not compete with the food processing industry.

Description of the invention and embodiments

The present invention aims to recover ellagic acid from industrial streams of cellulosic pulp mills, or streams from other lignocellulosic materials processing industries, such as cooking liquors and bleaching line effluents.

Ellagic acid (EA) in the free form or linked to sugars by ester linkage (ET) is present in wood subjected to a delignification (cooking) process in the production of pulp for paper or other cellulose-based products. The cooking process consists of degradation and removal of lignin together with other components of the wood, thus releasing the cellulosic fibers (Evtuguin 2016) . During cooking, carried out at high temperature (130-170°C) , in an alkaline medium (such as the kraft process) or in an acid medium (such as the sulphite process) , a predominant part of EA is dissolved in the cooking liquor, while the other portion is present in the stream of raw pulp still submitted to bleaching (Rodrigues et al. , 2018) . Thus, there is a possibility of EA recovery from the cooking liquor or bleaching line effluents. The present invention relates to a method for recovering ellagic acid from an industrial stream of cellulosic pulp mills, or a stream from other lignocellulosic materials processing industries, comprising the following steps: a) Collecting a stream effluent and adjusting the pH between 0.1 and 14, and temperature between 1 and 100°C for subsequent conditioning; b) Conditioning of the effluent for a time between 0.1 and 720 hours in a container made of a material selected from metal derivatives, glass or plastics which are suitable for the crystallization of ellagic acid, wherein the effluent is conditioned at the pH and temperature adjusted in the previous step; c) Separation of the ellagic acid-containing precipitate obtained in the previous step via crystallization, wherein the separation is carried out by centrifugation or any other separation technique suitable for the purpose; d) Successive washing of the separated ellagic acid-containing precipitate with water and separation of the precipitate by centrifugation or any other separation technique suitable for the purpose ; e) Drying the obtained ellagic acid product.

In one embodiment, the industrial stream from cellulosic pulp mills, or stream from other lignocellulosic materials processing industries, is an effluent from acid sulphite processes, such as cooking liquors or bleaching line effluents.

In one embodiment, step a) is carried out after removing nonprocessed suspended matter.

In one embodiment, step b) is carried out at a conditioning temperature between 60 and 80°C when the effluent is cooking liquor. In another embodiment, step b) is carried out at a conditioning temperature between 20 and 40°C when the effluent is an alkaline bleaching effluent. In one embodiment, the pH of the effluent in steps a) is adjusted between 0.1 and 14. In another embodiment, the pH of the effluent in step a) is adjusted between 2 and 5.

In one embodiment, step b) occurs with an effluent conditioning time comprised between 0.1 and 720 hours. In another embodiment, the conditioning time is above 720 hours.

In one embodiment, the container used in step b) is made of a material selected from, but not limited to: metal derivatives, such as variants of stainless steel; as well as glass, mainly with a large percentage of borosilicate, between 65 and 80% of silica (SiO2) and between 8 and 25% of boron trioxide (B2O3) ; plastic such as polyethylene terephthalate or high-density polyethylene; or other materials that have chemical and/or physical similarities, providing the same conditions suitable to promote selective crystallization of ellagic acid.

In one embodiment, step d) is a step of successive washing of the ellagic acid-containing precipitate with water, which however does not qualify as a specific purification step. The number of washes and the amount of water used will depend on the effluent used and isolation conditions.

In one embodiment, step d) is carried out using acidified water comprising HC1 between 0.1 and 20% v/v, which can also be used for metal and other concomitants removal. The number of washing cycles and the amount of water used in it depend on the effluent used and the conditions for isolating the ellagic acid.

Step d) is influenced by the surface area-to-volume ratio (S/V) of the container used for processing, being preferred the use of containers with S/V values between 0.1 and 100 (nt ¹ ) to increase the number of nucleation centres during ellagic acid crystallization. In one embodiment, the S/V ratio can be above 100 (nV ¹ ) . In the end of the method, ellagic acid is obtained in powder form with purity ranging between 20 and 99% , without further purification, depending on the stream used and isolation conditions .

1 . Recovery of EA from cooking liquors

Given the low pK _a ( 5 . 4 -6 . 8 ) , EA is completely soluble in alkaline cooking liquors ( kraft black liquor pH is around 11 ) and very little soluble in acid sulphite cooking liquors (pH of SO2 solution is around 3 ) . Due to the symmetrical chemical structure ( Figure 1 ) and low solubility in water, EA easily forms crystals that can be recovered from the medium. This phenomenon occurs in a relatively simple way in the liquor from cooking with acid sulphite and the crystals formed are contaminated to a much lesser extent by components readily soluble in water ( lignosulphonates , sugars and their derivatives , organic acids and neutral extractables , among others ) . Therefore , it is possible to select the conditions for the recovery of the EA from the acid sulphite cooking liquor . Similarly, acidification of kraft cooking liquor to pH 1-5 also leads to the formation of EA crystals , but these are easily contaminated with poorly soluble liquor components at low pH values , which co-precipitate ( e . g . , kraft lignin and hemicelluloses , extractables , among others ) resulting in a complex mixture that requires extensive purification . Therefore , acid sulphite liquors are the most suitable effluents for the recovery of EA . In addition to the amount of EA in the processed wood and, therefore , its concentration in the acid sulphite cooking liquor , the amount and purity of EA will also depend on the pH and temperature of the liquor, the crystallization time and the contact material with the liquor at the time of crystallization . Another determining factor for the dynamics of the EA crystallization process is associated with the surface area-to- volume ( S/V) ratio of the container used as a crystallizer . The natural pH of the sulphite liquor, after elimination of free SO2 ( 2-3 ) , meets the necessary conditions for the crystallization of EA, while a pH greater than 5 will be harmful . The concentration of EA in liquor until saturation can be increased with its pre evaporation. The dynamics of crystal agglomerates formation in the Eucalyptus acid sulphite cooking liquor at pH 2.6 and low temperatures shows that the largest fraction of EA is formed in the first 1-5 days, following a slower dynamic later (Figure 2) . Although decreasing the crystallization temperature to 6°C leads to an increase in the precipitated matter in the liquor, the EA content in this material is lower than that found at the temperature of 20°C. This fact is due to the competitive process of crystal formation or accelerated precipitation of other components of the liquor. In fact, chemical analysis of the precipitate showed the co-precipitation of aldonic acids in the form of 5-lactones, sugars, low degree sulfonated lignin, different extractable compounds, and mineral salts. The dynamics of EA crystal formation at 20°C was higher than that observed at 6°C, reaching the maximum level more quickly (Figure 2) .

Another factor that influences the intensity of EA crystal formation is the surface area-to-volume (S/V) ratio of the container used for processing the cooking liquor. EA crystals are molecular aggregates that form intermolecular bonds under the appropriate thermodynamic conditions. These processes for crystallization and precipitation are dominated by primary nucleation around vessel walls. Therefore, the crystallization rate is dependent on the contact area and the type of material in the container. For the same material, e.g. , glass (Figure 3) , an increase in S/V ratio leads to greater precipitation of EA from the acid sulphite cooking liquor without apparently significant change in the final purity of the precipitate. At least in the S/V range of 0.5-2.0 (im ¹ ) a logarithmic dependence of the amount of liquor precipitate versus the same time (120 hours) and the same temperature (20°C) was observed.

Given the importance of the primary nucleation process of EA in contact with the container, it is logical that the origin of material in the container is a determining factor in the dynamics and purity of the precipitate. This fact becomes evident when comparing EA precipitation of the liquor at the same temperature (25°C) and during the same time (72h) of exposure in containers of different materials but with similar geometries (S/V=0.5-0.6 (nr ¹ ) ) . Among the selected container materials (stainless steel, glass, polyethylene terephthalate (PET) and high-density polyethylene (HDPE) ) , plastics showed the highest degree of EA purity in the precipitate, while the precipitate with the highest amounts was recorded for the stainless-steel container (Figure

4) . Therefore, by modifying the container material in contact with the liquor, it becomes possible to change both the amount and the purity of EA in precipitate. It is notable that the way EA adhered to the wall of the container was quite different. Therefore, the greatest adherence to the container wall was observed for PET, stainless steel and to a much lesser extent for glass. As mentioned above, increasing the conditioning temperature of the liquor results in a lower amount of precipitate formed, however, at the same time increasing the purity of the EA crystals (Figure 2) . This tendency is explained by the greater capacity of EA to form crystals in relation to aldonic acids, sugars, and mineral/organic salts and by the greater solubility of lignin in liquors with high temperatures. Consequently, there is a gradual increase in EA purity in precipitates obtained at higher temperatures (Figure

5) . In particular, the purity increased considerably with temperatures around 60-80°C (Figure 5) . Evidently, due to the increased solubility of EA and the thermodynamics of crystallization, the amount of EA precipitated at temperatures above 80°C has a tendency to decrease, making it also difficult to operate at temperatures close to 100°C, at atmospheric pressure. The liquor precipitate obtained by the described method has, in addition to EA, aldonic acids, sugars, lignin, different extractable lipophilic compounds and mineral/organic salts in its composition (Figure 6) . A large part of these compounds can be washed off with water, thus significantly increasing the EA purity up to values close to 90% (Figure 5) . The remaining contaminants are essentially low sulfonated lignin, extractable compounds and mineral/organic salts (Figure 6) . Among the mineral compounds, the main ones are magnesium (400-500 ppm) , potassium (300-400 ppm) and calcium (100-200 ppm) salts. It is also important to point out that after the isolation of EA from the liquor, the latter can be returned to the conventional pulp manufacturing process and used for energy and reagent recovery.

2. Recovery of EA from bleaching effluent

Other industrial streams that contain EA are bleaching effluents. In the case of the acid sulphite process, the first bleaching stage after washing the raw pulp is the alkaline extraction stage, which aims to purify the obtained pulp (Rodrigues et al., 2018) . The EA contained in the raw (unbleached) pulp, in this case, is extracted in an alkaline medium (pH> 11) and remains in the effluent. Bearing in mind that this stage does not use any oxidizing agent, it is possible to preserve the EA against degradation and isolate it from the alkaline effluent in higher amounts. In the case of bleaching kraft pulp, the first stages of bleaching are normally aimed at removing residual lignin with oxidative reagents that degrade the EA. Considering the lower amount of EA present in the washed kraft pulp streams than in the sulphite pulp streams (Rodrigues et al., 2018) and the existing bleaching practice, alkaline extracts from bleaching kraft pulps are less suitable for the isolation of EA than alkaline extracts from acid sulphite pulps.

The effluent from the alkaline extract, after pulp treatment with acid sulphite, has a pH close to 10 and must be acidified for the precipitation of EA to occur. However, acidification below pH 4 leads to non-selective co-precipitation of the various constituents of the extract (extractable substances, lignin removed from the pulp, hemicelluloses and beta-cellulose, among others) , which does not allow a selective isolation of the target product. At the same time, the adjustment of pH 5 of the liquor (slightly below pKa of EA) , at temperature 20-40°C, allows the collection of a precipitate with a reasonable content of EA (Figure 7) . The drop in the exposure temperature of the alkaline extract below 20°C showed a drastic drop in EA content in the precipitate (less than 10% at a temperature of 10°C with 24h of exposure) . Due to a strong dilution of the alkaline extract in the pulp mill , the amount of EA recovered, considering comparable conditions , is considerably lower than that obtained from the cooking liquor ( Figure 2 ) . The degree of purity of EA in the alkaline extract precipitate is also lower than that obtained from the cooking liquor . At the same time , the precipitation dynamics of the alkaline extract acidified to pH 5 , in a way, is similar to that of the cooking liquor , however the maximum level of precipitated EA is reached more rapidly ( Figure 7 ) .

The increase in temperature to values above 40 °C causes the coprecipitation of the polysaccharides dissolved in the alkaline extract of the sulphite pulp, essentially beta-cellulose , thus making the isolation of EA difficult . The main contaminants present in the precipitate , obtained at pH 5 and temperature 30 ° C for 24 hours , are derived from extractable compounds and lignin . Washing the precipitate with water also increases the purity of EA isolated from the alkaline extract , however these values are much lower than those obtained from the acid sulphite cooking liquor ( Figure 2 ) . Thus , in order to obtain EA with a higher degree of purity, it is necessary to apply a specific purification process .

It is important to note that after the isolation of EA from the alkaline extract , the latter can be returned to the conventional pulp manufacturing process .

Ellagic acid is a biologically active substance and is intended as a raw material for the pharmaceutical , cosmetic, food and chemical industries .

Application examples

For a better understanding of the main points of the invention, examples of preferred procedures of the method are described below, which, however, are not intended to limit the final obj ective of the present invention . Recovery of ellagic acid from acid sulphite cooking liquor

2000 cm ³ of eucalypt wood (Eucalyptus globulus) magnesium-based acid sulphite industrial cooking liquor, taken at the exit of the last evaporation effect (dry content ca . 14%) , with a temperature ca. 70°C and pH 2.3, were placed in a closed glass container with the S/V ratio ca. 0.5 (nu ¹ ) . After 96 hours of contact, the liquor was decanted, and the precipitate was separated by centrifugation. The amount of dry residue of the precipitate was 1.123 g with an EA content ca . 70% according to GC-MS analysis based on retention time and standard mass spectrum (Rodrigues et al. , 2018) . The residue was washed successively 5 times with water at 20°C (5 x 20 ml) , first with water acidified with HC1 to pH 2 and then with distilled water, for a total of ca. 100 cm ³ per 1g of precipitate, centrifuging the sample after each wash. The precipitate washed with water was dried at 30°C in the vacuum oven, obtaining in the end a dry precipitate of 0.820 g with an EA content of 95% detected by GC-MS analysis using the quantitative method by the standard response factor. According to the data obtained by solid state ¹³ C NMR (Figure 8) , during washing with water most of the sugar derivatives and a part of lignin were removed. In fact, the series of signals between 50 and 90 ppm (carbons from the lignin side chain and non-anomeric carbons from sugars and their derivatives) decreased significantly. The washed sample also revealed the presence of residual lignin (peak at 56 ppm attributed to methoxyl groups) , sugars and their derivatives (peak at 64 ppm attributed to methylol groups) and trace amounts of extractable compounds (weak signals in the region 10-30 ppm) . The precipitate showed the presence of EA crystals according to the X-ray dif f ractogram (Figure 9) , obtained and compared with the EA standard (Sigma- Aldrich®, h 96%, E2250, Saint Louis, USA) . The characteristic reflection of the EA crystals at 2028.2° (Figure 10) corresponding to the distance between the planes of the adjacent layers of EA (3.2 A) and the reflection at 20 20.6° corresponding to the distance between the planes of stacked molecules (4.3 A) , clearly approximates to the dimensions of the triclinic cell described above (Rossi et al., 1991) . Some discrepancies between the dif f ractogram signals of the precipitate and the standard are due to the difference in molecular rearrangements, with the concomitant and eventual metallic complexes promoting a variety of different crystalline groups of isolated EA. The water-washed liquor precipitate also showed a ¹ H NMR spectrum in DMSO-d6 with a singlet at 5 7.45 (2H, ArH) and a broad singlet cantered at 5 10.65 (4H, Ph-OH) . These values are also in agreement with those described in the literature (Li et al. , 1999; Goriparti et al., 2013) .

Recovery of ellagic acid from bleaching effluent

2000 cm ³ of industrial alkaline extract after the first stage of the E-O-P bleaching line (alkaline extraction-oxygen delignif ication-hydrogen peroxide bleaching) of acid sulphite pulp obtained from E. globulus wood by magnesium acid sulphite- based cooking, were collected from the washing press at a temperature of approximately 70°C in an HDPE container. The extract was rapidly cooled to a temperature of 50 °C and the initial pH of 10 was adjusted to 7 using 20% sulfuric acid (m/m) . After cooling to 20°C the extract was acidified again to pH 5.0 and placed in a glass vessel with an S/V ratio of 0.67 (nr ¹ ) . After 24 h of exposure at 20°C, the formed precipitate was separated from the extract by decantation followed by centrifugation. The amount of dry residue of the precipitate was 0.150 g with an EA content of 25% according to GC-MS analysis. The residue was washed successively 5 times with water at 20°C (5 x 3 ml) , first with water acidified with HC1 to pH 2 and then with distilled water, for a total of approx. 100 cm ³ per 1g of precipitate, centrifuging the sample after each wash. The precipitate washed with water was dried at 30 °C in the vacuum oven, obtaining in the end a dry precipitate of 0.090 g with an EA content of 39% detected by GC- MS analysis using the quantitative method by the standard response factor .

Brief description of figures

For a better understanding of the key points of the invention, the figures that aim to demonstrate the preferred procedures of the method are attached, which, however, do not intend to limit the final objective of the present invention.

Figure 1 shows the chemical structure of ellagic acid with the numbering of the carbon atoms.

Figure 2 shows the content of ellagic acid (EA) in the precipitate from industrial acid sulphite cooking liquor (liquor A sample) from E. globulus wood, collected at different exposure times, in a borosilicate glass container with a ratio surface area/volume (S/V) of 0.67 (nt ¹ ) at temperatures of 6 and 20°C.

Figure 3 shows the content of ellagic acid (EA) in a precipitate of industrial acid sulphite cooking liquor (sample of liquor B) from E. globulus wood, collected at different exposure times, in borosilicate glass containers with the ratios surface area/volume (S/V) of 0.67 and 0.73 (nt ¹ ) at a temperature of 20°C (Figure 3A) . The influence of the surface area-to-volume ratio (S/V) of borosilicate glass containers at a temperature of 20°C, for the same acid sulphite liquor, is represented in Figure 3B.

Figure 4 shows the influence of the container material on the content of the precipitate and on the ellagic acid (EA) content in a precipitate from acid sulphite industrial liquor (liquor C sample) from E. globulus wood, exposed for 72 hours, at room temperature ca. 25°C, in containers of similar geometry (S/V=0.4- 0.5 (nV ¹ ) ) . Designation of materials: borosilicate glass (glass) ; stainless steel (stainless) ; high density polyethylene (HDPE) and polyethylene terephthalate (PET) .

Figure 5 shows the effect of exposure temperature of acid sulphite industrial liquor (liquor D sample) from E. globulus wood, in a borosilicate glass container with S/V 0.63 (nV ¹ ) , on the amount of precipitate and acid content ellagic acid (EA) in a precipitate before and after washing with water.

Figure 6 represents the composition of unwashed and water washed precipitates. The precipitates were obtained by exposing acid sulphite industrial liquor (liquor E sample) from E. globulus wood in a borosilicate glass vessel with S/V 0.63 (nt ¹ ) for 72h at a temperature of 85 °C.

Figure 7 shows the content of ellagic acid (EA) in the unwashed and water-washed precipitate of the alkaline extract (sample Al) from the extraction stage (E) of the E-O-P bleaching of acid sulphite industrial pulp of E. globulus wood, collected at different exposure times, in a borosilicate glass container with a surface area-to-volume ratio (S/V) of 0.67 (im ¹ ) at a temperature of 20°C.

Figure 8 shows the X-ray dif f ractograms of the precipitate from industrial acid sulphite liquor (sample of E liquor) of E. globulus wood obtained under conditions described in Figure 6 and the ellagic acid pattern (source Cu-Ka with =0.154 nm, in the range 20 2-40° and scan step width of 0.02° / per scan) .

Figure 9 shows the CP-MAS ¹³ C NMR spectra of the precipitate, unwashed and washed with water, and ellagic acid (EA) standard.

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