GR20200100195A - Integrated technology for the production of nanotubes cnts - Google Patents

Abstract

Tubular cellulose (TC) is obtained by de-lignification of lignocellulosic biomass. Lignocellulosic, raw and de-lignified materials were studied by SEM images, XRD spectroscopy and porosimetrically. For further hydrolysis of TC in nanotubes (CHNTs), the fungus Trichoderma ressei was grown to produce cellulase enzymes. The resulting CHNTs were studied by SEM images and porosimetrically. Also, the water-soluble CHNTs in the TC hydrolysis supernatant were dried by lyophilization and studied porosimetrically and with TEM images. Composite polymers (CP) with starch were prepared from TC followed by hydrolysis with cellulases / amylases. The resulting CP of the CHNTs were studied porosimetrically. The CHNTs, as well as their CP, can be used as carriers of chemical additive (s) for their controlled release in food / beverages as well as for the inclusion of a drug active substance for its controlled release.

Description

Description

Integrated production technology of carbohydrate nanotubes (Carbohydrate Nanotubes, CHNTs) and their Composite Polymers (CP).

The present invention concerns the production of carbohydrate nanotubes (Carbohydrate Nanotubes, CHNTs) and their Composite Polymers (CPs), in liquid or dry form, from de-ligninized cellulose (Tubular Cellulose (SC)).

Carbohydrate nanotubes (CHNTs) are produced by an enzymatic process of apoliginized cellulose (SC), which apoliginized cellulose is prepared by chemical treatment of lignocellulosic biomass. The lignocellulosic biomass used can be of any plant origin.

The purpose of the present invention is the utilization of lignocellulosic biomass, an abundant, renewable, biodegradable, light biopolymer, as a basis for the production of up to nanotubes, which in the context of the continuous development and application of biotechnology will find many applications, e.g. in food, medicines, materials, etc. Carbon nanotubes (CHNTs) have the advantage over carbon nanotubes (CNTs) (graphenes, fullerenes) that they can be hydrolyzed by enzymes to glucose, and in addition they are GRAS (Generally Recognized As Safe).

Example 1.

For deligninization, the lignocellulosic material of various origins (e.g. wheat straw, sunflower stem, etc.) is treated with NaOH solution and heated to 70 °C for 3 h. Thus, the cellulosic apoligninized material tubular cellulose (SC) is obtained. Next, the material is washed and dried. SEM images and XRD spectra were obtained for the raw lignocellulosic materials and delignified cellulosic materials (SC), as well as porosimetry analyzes (Table 1).

Examples 2 and 3 describe the production of spores from Trichoderma ressei, and then of the cellulase enzymes respectively, which will be used for the hydrolysis of the SC and obtaining CHNTs.

Example 2.

The fungus, Trichoderma ressei, was grown on Potato Dextrose Agar (PDA) solid medium. The nutrient medium was sterilized at 120 °C for 15 min. The culture was grown at 30 °C in 7 days. The spores produced were aseptically collected in order to produce the cellulases enzymes to hydrolyze the SC, as described in example 3.

Example 3.

For the production of cellulases, 2 mL of the spore suspension in water was used, transferred to 60 mL of sterile nutrient medium consisting of 20 g/L delignized dry sawdust, 10 g/L soy peptone, 10 g/L glucose, and allowed to incubate at 30 °C and 180 rpm for 24 h. Next, 40 mL of the above resulting medium was added to 1 L of sterile nutrient medium consisting of 25 g/L delignized dry sawdust, 17 g/L soy peptone, 5 g/L (NH4)2SO4, 6 g/L KH2PO4, 2.05 g/L MgSO4* 7 H2O, 2.5 g/L glycerol, 2 mL/L Tween 20 allowed to incubate at 300 rpm, temperature 26 °C, aeration 1.5 L/min and pH adjusted to 5.

Example 4.

This is followed by the hydrolysis of the delignified dry cellulose (SC), using 10-15 g of it, 200 mL of sodium citrate buffer pH = 5.0 and 10 mL of the cellulase solution from example 3, carried out at a temperature of 50 °C without stirring. For the (CHNTs) products, SEM images were obtained and nitrogen sorption-desorption porosimetry analyzes were performed to determine their specific surface area, pore diameter as well as their volume in order to find the best (CHNT) product (Table 2).

Example 5.

From example 4 and based on Table 2, corn cob was selected as the best material. It was hydrolyzed as described in Example 4, and the supernatant of the hydrolyzed solid (CHNT) was sampled to detect its water-soluble CHNTs. The liquid samples were then dried by lyophilization. The resulting powder was analyzed by nitrogen desorption porosimetry (Table 3), and TEM images were obtained.

Example 6.

To prepare the CHNTs starch composite polymers (SPs), a starch gel (SP) containing 5% starch was prepared, an appropriate amount of this was added to the powdered SC, from each cellulosic material, and stirred very well so that the SP was uniformly covered the surfaces of cellulosic materials. Then, the tubular cellulose-starch gel (SC-PA) composite polymers (SP) were freeze dried followed by porosimetry analysis (Table 4). Example 7.

This is followed by the hydrolysis of the SK-PA composite polymers using 10-15 g of them. To each of them, 200mL of 0.02M phosphoric acid buffer solution pH=7 was added and left for 30 min at 40 °C. After 30 min, commercial α-amylase 320U enzyme was added and left for 2 h at 40 °C, without stirring. This was followed by washing with 100 mL of 0.05 M sodium acetate buffer pH=4.7. After washing the composite polymers, 100 mL of 0.05 M sodium acetate buffer solution pH=4.7 and 640U cellulase enzyme, commercial, were added to each of them. They were left at 40 °C, without stirring. Nitrogen desorption porosimetry analyzes were performed for the resulting materials to determine their specific surface area, pore diameter, as well as their volume (Table 5).

Table 1. Specific surface area, pore volume and pore size for delignified (SK).

ABET (m<2>/g) Pore size BET (nm)

Cellulosics Untreated Pelignified Untreated Pelignified U Wheat straw 0.48 1.12 8.23 6.86

Sun flower stem 1.70 1.47 6.41 9.99

Corn cob 0.34 0.89 8.78 11.15

Sawdust 0.60 1.02 4.48 7.33

raw lignocellulosic materials and the like

Macro-.Mesopore (1.7-300 nm) _

ABJH(m<2>/g) VBJH (cm<3>/g) Pore size BJH (nm)

ntreated Pelignified Untreated Per size Untreated Pelignified 0.22 0.36 0.0034 0.0056 63.42 61.28

1.63 1.50 0.0060 0.0085 14.81 22.75

0.18 0.85 0.0026 0.0065 57.29 30.26

0.17 0.38 0.0033 0.0062 76.79 64.90 CELLULOSICS

WHEAT STRAW SUN FLOWER STEM CORN COB SAWDUST BET SURFACE AREA (m<2>/g)

5 H 0.99 0.72 1.14 0.69 24 H 1.18 0.76 1.79 1.10 48 H 1.20 1.04 0.87 1.32 72 H 1.07 0.70 0.52 0.73 504 H 2.17 1.09 0.98 1.01 672 H 1.97 1.26 1.68 1.74 BJH DESORPION CUMULATION VOLUME OF PORES

between 17,000 A and 3000,000 A width (cm<3>/g)

5 H 0.0058 0.0032 0.0090 0.0054 24 H 0.0082 0.0050 0.013 0.0056 48 H 0.0091 0.0038 0.0050 0.0062 72 H 0.0074 0.0048 0.0033 0.0053 504 H 0.012 0.0047 0.0052 0.0054 672 H 0.012 0.

5 h 81.45 81.86 116.62 61.67 24 h 103.08 87.52 136.52 79.21 48 h 69.50 69.66 81.26 75.22 72 h 88.35 84.11 70.09 70.60 504 h 80.11 68.54 83.10 66.55 672 h 94.71 86.26 122.50 72.34 Πίνακας 2. Ειδική επιφάνεια, όγκος πόρων και μέγεθος πόρων για τα προκύπτοντα materials (CHNTs) after the hydrolysis of SC.

Table 3. Specific surface area, pore volume and pore size for the powder obtained by lyophilization of the SK hydrolysis supernatant from Example 5.

_ Liquid of hydrolysis

BET SURFACE AREA (m<2>/g)

24 h 0.79

BJH Desorption cumulative volume of pores

between 17.000 A and 3000.000 A width (cmVg)

24 h 0.0040

72 h 0.0069

AVERAGE PORE DIAMETER (A)

24 h 36.05

72 h 46.04

Table 4. Specific surface area, pore volume and pore size for delignified cellulosic materials (SC) and corresponding tubular cellulose-starch gel (SC-PA) composite polymers (SC).

BJH Desorption cumulative volume of

BET SURFACE AREA pores AVERAGE PORE DIAMETER BY (m<2>/g) between 17.000 A and 3000.000 A width BET (A)

(cm<3>/g)

Cellulosics DEliGNiFiED STARCH GEL PELIGNIFIEP STARCH ..GEL

Wheat1.120.86 0.0056 0.0043 68.57 43 32 straw

Sun flower

1.47 0.80 0.0085 0.0031 99.92 61.02 stem

Corn cob 0.89 0.72 0.0065 0.0035 111.46 66.62 Sawdust 1.02 0.26 0.0062 0.0022 73.26 10.35

Table 5. Specific surface area, pore volume and pore size for the resulting materials after hydrolysis of SK-PA.

CELLULOSICS

WHEAT STRAW BET SURFACE AREA (m<2>/g)

5h 4.29

24 h 3.78

48 h 2.43

72 h 2.43

BJH Desorption cumulative volume of pores

between 17,000 A and 3000,000 A width (cm<3>/g)

5 h 0.045

24 h 0.040

48 h 0.034

72 h 0.028

AVERAGE PORE DIAMETER (A)

5 h 231.10

24 h 267.07

48 h 236.36

72 h 216.03

SUN FLOWER STEM CORN COB SAWDUST

2.21 1.85 1.56

2.99 0.84 3.03

3.44 1.21 2.99

3.36 0.92 3.27

0.021 0.019 0.014

0.024 0.0083 0.032

0.031 0.016 0.032

0.029 0.0092 0.031

209.51 234.43 176.98 181.49 190.77 202.52 234.43 200.74 205.27 185.28 189.75 197.44

Claims (5)

1. Hydrocarbon nanotubes (CHNTs) as well as their composite polymers (SP) with various polysaccharides such as starch of any form, origin or processing, agar, chitin, chitosan, carrageenan, etc., characterized by the fact that they can be liquid or /and dry. 2. Method for the production of carbohydrate nanotubes (CHNTs) according to claim 1, characterized in that the CHNTs result from the treatment of lignocellulosic biomass, of plant or bacterial origin, with chemical agents (acids, bases, etc.), microorganisms or enzymes. 3. Hydrocarbon nanotubes (CHNTs) as well as their composite polymers (CP) according to claims 1 and 2, wet and/or dry by heating, aeration, and/or lyophilization. 4. Use of CHNTs as well as their composite polymers (CP) according to claims 1, 2 and 3, characterized in that they are used in a wide range of temperatures and pH. 5. Use of CHNTs as well as their composite polymers (CP) according to claims 1 to 4 as encapsulation carriers of chemical additive(s) for their controlled release in food and beverages, as well as encapsulation of active substance in drugs and materials.