Method for preparing peat moss nanocellulose, applications, a composite film

Abstract

The application discloses a preparation method and application of peat moss nanocellulose and a composite film. Cellulose in peat moss is used as a raw material, chemical extraction is first performed on the cellulose, the cellulose is then converted into nanocellulose material through a sulfuric acid hydrolysis method, and finally the prepared nanocellulose is used as a reinforcing agent and applied to preparation of a degradable sodium alginate composite film material.

Description

Technical field

[0001] The invention belongs to the technical field of preparing nanocellulose, and in particular relates to a preparation method and application of peat moss nanocellulose and a composite film. [Background Technology]

[0002] Sphagnum moss is primarily used as a culture medium for precious flowers and as a gardening material, but its chemical content is relatively unavailable. Conventional nanocellulose production often uses woody or herbaceous plants as raw materials. The present invention extracts cellulose from the moss plant Sphagnum moss, converts it into nanocellulose through sulfuric acid hydrolysis, and uses the resulting nanocellulose to prepare a degradable sodium alginate composite membrane material. [Summary of the invention]

[0003] In response to the above problems, the present invention provides a preparation method, application, and a composite membrane of peat moss nanocellulose. The cellulose in peat moss is used as a raking material, which is first chemically extracted and then converted into a nanocellulose material by sulfuric acid hydrolysis. Finally, the prepared nanocellulose is used as a reinforcing agent and applied to the preparation of a degradable sodium alginate composite membrane material.

[0004] The purpose of the present invention is achieved through the following technical solutions:

[0005] A method for producing peat moss nanocellulose comprises the following steps:

[0006] (1) adding peat moss to a NaOH solution and reacting in a Parr reactor; after the reaction is completed, centrifuging the suspension, removing the supernatant, and continuing centrifugation to wash the precipitate I;

[0007] (2) adding hydrochloric acid solution to the washed precipitate I to adjust the pH value of the suspension to neutral, centrifuging, removing the supernatant, and drying the precipitate to obtain precipitate II;

[0008] (3) After adding deionized water to Precipitate II, glacial acetic acid and sodium chlorite were added three times, each time in a constant temperature water bath at 75°C. After cooling, centrifugation was performed to obtain Precipitate III, which was freeze-dried to obtain peat moss cellulose.

[0009] (4) Weigh the freeze-dried peat moss cellulose, add 60wt% H2SO4 solution, add 10 times the volume of deionized water after constant temperature water bath, and the reaction is completed. Then centrifuge the suspension, remove the supernatant to obtain precipitate IV, and then centrifuge and purify it with deionized water until the pH value of the supernatant is 5. Collect the precipitate into a dialysis bag and dialyze it with deionized water. During the dialysis process, replace it with new deionized water several times until the pH value of the dialyzate no longer changes; treat the suspension in the dialysis bag with ultrasound, and then freeze-dry the suspension to obtain peat moss nanocellulose.

[0010] It is further stated that the material-liquid ratio of the peat moss to the NaOH solution is 1:15.

[0011] Further, in step 1), the reaction conditions in the Parr reactor are stirring at 140° C. for 3 h; and the stirring speed is 220 rpm.

[0012] Further description, in step 1), the centrifugation condition is 8000 rpm for 10 minutes.

[0013] Further, in step 3), the mass ratio of the precipitate II, glacial acetic acid, sodium chlorite and ionized water is 2:0.5:0.6:60; and the time of the constant temperature water bath is 1 hour.

[0014] It is further explained that in step 4), the material ratio of the peat moss cellulose to the H2SO4 solution is 1:15.

[0015] Further description: in step 4), the temperature of the constant temperature water bath is 45° C., and the time of the constant temperature water bath is 60 minutes.

[0016] Further, in step 4), the suspension is centrifuged at 8000 rpm; the suspension is centrifuged for 10 minutes.

[0017] Further, in step 4), the ultrasonic treatment conditions are: total treatment time 20 min, nanocellulose concentration of sphagnum moss prepared 4 wt%, ultrasonic power 650 W, operation time 6 s, and rest time 3 s.

[0018] The present invention also provides an application of the nanocellulose obtained by the method for preparing the peat moss nanocellulose to prepare a degradable sodium alginate composite membrane material.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] The invention uses cellulose in peat moss as raking material, first chemically extracts the cellulose, then converts it into nanocellulose material through sulfuric acid hydrolysis, and finally uses the prepared nanocellulose as a reinforcing agent for the preparation of degradable sodium alginate composite membrane material.

Brief Description of the Drawings

[0021] Figure 1 This is a morphological diagram of peat moss raw materials;

[0022] Figure 2 This is a morphological diagram of the peat moss cellulose prepared for this application;

[0023] Figure 3 This is a morphology diagram of the peat moss nanocellulose prepared in this application;

[0024] Figure 4 is a particle size distribution curve of peat moss nanocellulose of the present invention;

[0025] Figure 5 This is a TEM image of the peat moss nanocellulose of the present invention. [Specific implementation method]

[0026] All features disclosed in this specification, or all steps in the disclosed methods or processes, except mutually exclusive features and / or steps, can be combined in any manner.

[0027] Any feature disclosed in this specification (including any accompanying claims and abstract), unless otherwise stated, is merely one example of a series of equivalent or similar features.

[0028] Example 1:

[0029] A method for producing peat moss nanocellulose comprises the following steps:

[0030] (1) Peat moss was added to NaOH solution at a material-liquid ratio of 1:15, and stirred at 220 rpm in a Parr reactor at 140°C for 3 h; after the reaction, the suspension was centrifuged at 8000 rpm for 10 min, the supernatant was removed, and the precipitate I was washed by centrifugation again;

[0031] (2) adding hydrochloric acid solution to the washed precipitate I to adjust the pH value of the suspension to neutral, centrifuging, removing the supernatant, and drying the precipitate to obtain precipitate II;

[0032] (3) After adding 2 g of precipitate II to 60 mL of deionized water according to the ratio, 0.5 mL of glacial acetic acid and 0.6 g of sodium chlorite were added three times, each time in a 75°C water bath for 1 h. After cooling, centrifugation and washing were performed to obtain precipitate III, which was freeze-dried to obtain peat moss cellulose;

[0033] (4) Weigh the freeze-dried peat cellulose, add 60wt% H2SO4 solution according to the material ratio of 1:15, and add 10 times the volume of deionized water after 60 minutes in a constant temperature water bath at 45℃. After the reaction is completed, the suspension is centrifuged at 8000rpm for 10 minutes, and the supernatant is removed to obtain precipitate IV, which is then purified by centrifugation with deionized water until the pH value of the supernatant is 5. The precipitate is collected in a dialysis bag and dialyzed with deionized water. New deionized water is replaced several times during the dialysis process until the pH value of the dialyzate no longer changes; the suspension in the dialysis bag is treated with ultrasound for 20 minutes (the concentration of peat moss nanocellulose is 4wt%, the ultrasonic power is 650W, the operation time is 6s, and the interval time is 3s), and then the suspension is freeze-dried to obtain peat moss nanocellulose.

[0034] Experimental example:

[0035] 1.1 Materials

[0036] Fresh peat moss was purchased from Zhejiang Lanting Qingcheng Technology Co., Ltd., and after being thoroughly cleaned, it was placed in an oven and dried at 50°C, crushed, and sieved through a 300-mesh sieve to obtain the peat moss raw material ( Figure 1 Dialysis bags (8000-14000 Da, Viskase, USA), sodium alginate (average molecular weight 250K, Tianjin Yongda Reagent Co., Ltd.), and other chemical reagents used in the experiment were of analytical grade.

[0037] 1.2 Preparation of peat moss cellulose

[0038] In a Parr reactor, peat moss raw material and 10% (w / v) NaOH solution were added at a material-liquid ratio of 1:15, and stirred at 140°C for 3 hours at a stirring speed of 220 rpm. After the reaction, the suspension was centrifuged at 8000 rpm for 10 minutes, the supernatant was removed, and the precipitate was washed 3 times by centrifugation with deionized water. The pH value of the suspension was adjusted to neutral with hydrochloric acid solution, centrifuged, the supernatant was removed, and the precipitate was dried. 2 g of the precipitate was weighed, 60 mL of deionized water was added, and 0.5 mL of glacial acetic acid and 0.6 g of sodium chlorite were added 3 times. Each time, the mixture was water bathed at 75°C for 1 hour. After cooling, the mixture was centrifuged and washed. The product was freeze-dried to obtain peat moss cellulose ( Figure 2 ).

[0039] 1.3 Preparation of peat moss nanocellulose

[0040] Weigh the freeze-dried peat cellulose, add 60wt% H2SO4 solution at a material-liquid ratio of 1:15, transfer to a 45°C water bath, and add 10 times the volume of deionized water after 60 minutes to terminate the reaction. Centrifuge the suspension at 8000rpm for 10 minutes, remove the supernatant, and purify the precipitate with deionized water by centrifugation until the pH value of the supernatant is about 5. Collect the precipitate in a dialysis bag and dialyze it with deionized water. During the dialysis process, replace it with new deionized water several times until the pH value of the dialysate no longer changes. Treat the suspension in the dialysis bag with ultrasound for 20 minutes (concentration 4wt%, power 650W, operation time 6s, intermittent time 3s), and freeze-dry the suspension to obtain peat moss nanocellulose ( Figure 3 ).

[0041] The particle size distribution of peat moss nanocellulose samples was determined by dynamic light scattering (DLS). Figure 4) showed that the prepared sphagnum moss nanocellulose sample had a uniform particle size and good monodispersity, with an average particle size of 419.0 nm. Zeta potential measurement results showed that the prepared sphagnum moss nanocellulose had a zeta potential of -62.4 mV, and no significant sedimentation was observed after 48 hours of stabilization.

[0042] Figure 5 This is a TEM image of peat moss nanocellulose. The prepared peat moss nanocellulose has a diameter of about 21.5nm and is slender, which falls within the size range of nanomaterials.

[0043] 1.4 Preparation and mechanical properties testing of sodium alginate composite membrane

[0044] Sodium alginate composite film was prepared by solution casting. A certain amount of peat moss nanocellulose was dispersed in 200 mL of deionized water, 0.232 g of glycerol was added as a plasticizer, and the mixture was heated to 60 ° C in a water bath. 3.872 g of sodium alginate was added and stirred continuously throughout the process to obtain a uniform mixture. After 20 minutes of ultrasonic degassing, the mixture was poured onto a clean glass plate mold (22 cm × 22 cm), transferred to an oven, and dried at 90 ° C for 105 minutes. Finally, the composite film was peeled off and balanced at 25 ° C and 50% humidity for 48 hours for subsequent testing. The dosage of peat moss nanocellulose was 0.2%, 0.5%, and 1% (relative to sodium alginate), respectively.

[0045] The tensile index of the sodium alginate composite film is tested according to GB / T 12914-2008, and the burst index is tested according to GB / T 454-2002.

[0046] Table 1 Comparison of mechanical properties of sodium alginate composite films with different amounts of peat moss nanocellulose

[0047] Sphagnum moss nanocellulose dosage (%) 0 0.2 0.5 1.0 Tensile index (Nm / g) 33.38 40.14 40.33 40.54 <![CDATA[Bursting strength index (kPa·m 2 / g)]]> 242.64 270.53 274.26 280.63

[0048] Sodium alginate composite films with different amounts of peat moss nanocellulose were prepared and the mechanical properties of the composite films were tested. The results are shown in Table 1. When 1% peat moss nanocellulose was added as a reinforcing agent to the sodium alginate composite film, the tensile index (Nm / g) and burst resistance index (kPa·m 2 / g) increased by 21.2% and 15.7%, respectively.

[0049] The above description is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this field, it is possible to make several improvements and changes without departing from the creative concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A method for preparing peat moss nanocellulose and its use in a degradable sodium alginate composite film material, characterized in that: The method of using peat moss nanocellulose comprises the following steps: (1) Add peat moss to NaOH solution and react in a Parr reactor. After the reaction is completed, centrifuge the suspension, remove the supernatant, and continue centrifugation to wash the precipitate I; (2) Adding hydrochloric acid solution to the washed precipitate I to adjust the pH value of the suspension to neutral, centrifuging, removing the supernatant, and drying the precipitate to obtain precipitate II; (3) After adding deionized water to Precipitate II, glacial acetic acid and sodium chlorite were added three times, each time in a constant temperature water bath at 75 °C. After cooling, centrifugation was performed to obtain Precipitate III, and Precipitate III was freeze-dried to obtain peat moss cellulose; (4) Weigh the freeze-dried peat cellulose, add 60 wt% H2SO4 solution, and add 10 times the volume of deionized water after constant temperature water bath. After the reaction is completed, centrifuge the suspension and remove the supernatant to obtain precipitate IV, which is then purified by centrifugation with deionized water until the pH value of the supernatant is 5. Collect the precipitate in a dialysis bag and dialyze it with deionized water. During the dialysis process, replace it with new deionized water several times until the pH value of the dialyzate no longer changes. Treat the suspension in the dialysis bag with ultrasound, and then freeze-dry the suspension to obtain peat moss nanocellulose.

2. The use according to claim 1, characterized in that: In step 1), the material-liquid ratio of the peat moss to the NaOH solution is 1:

15.

3. The use according to claim 1, characterized in that: In step 1), the reaction conditions in the Parr reactor are stirring at 140°C for 3 h; the stirring speed is 220 rpm.

4. The use according to claim 1, characterized in that: In step 1), the centrifugation condition is 8000 rpm for 10 minutes.

5. The use according to claim 1, characterized in that: In step 3), the mass ratio of the precipitate II, glacial acetic acid, sodium chlorite and deionized water is 2:0.5:0.6:60; and the constant temperature water bath time is 1 hour.

6. The use according to claim 1, characterized in that: In step 4), the material ratio of the peat moss cellulose to the H2SO4 solution is 1:

15.

7. The use according to claim 1, characterized in that: In step 4), the temperature of the constant temperature water bath is 45°C, and the time of the constant temperature water bath is 60 min.

8. The use according to claim 1, characterized in that: In step 4), the suspension is centrifuged at 8000 rpm and the suspension is centrifuged for 10 minutes.

9. The use according to claim 1, characterized in that: In step 4), the ultrasonic treatment conditions are: total treatment time of 20 min, nanocellulose concentration of sphagnum moss prepared at 4 wt%, ultrasonic power of 650 W, operation time of 6 s, and rest time of 3 s.

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