CN106009458B - A kind of pineapple bran cellulose-g- acrylic acid/kaolin/sepia gel and the preparation method and application thereof - Google Patents

Abstract

The invention discloses a novel hydrogel of pineapple pomace cellulose-g-acrylic acid/kaolin/sepia ink, a preparation method and application thereof. The present invention uses pineapple peels as raw materials, and obtains pineapple peels cellulose after cleaning, drying, pulverizing, bleaching, and lye treatment. The pineapple peels cellulose is heated and stirred in an ionic liquid to dissolve, and ammonium persulfate is used as a trigger. N, N-methylenebisacrylamide is used as crosslinking agent, acrylic acid is used as monomer, graft modification is carried out, then kaolin and squid ink are added, after the reaction is completed, cool to room temperature, add distilled water to soak and wash, freeze-dry to obtain Hydrogels. The raw materials used in the invention have abundant sources, are convenient and easy to obtain, and have good economical efficiency. In the present invention, the process of preparing hydrogel after modifying the pineapple pomace cellulose is simple, the reaction time is short, the thermal stability of the hydrogel can be improved by squid ink and kaolin, and the obtained hydrogel is widely used in the field of waste water treatment and adsorption materials It has a good application prospect.

Description

A kind of pineapple pomace cellulose-g-acrylic acid/kaolin/squid ink gel and its Preparation method and application

technical field

The invention belongs to the technical field of composite hydrogel, and in particular relates to a pineapple pomace cellulose-g-acrylic acid/kaolin/squid ink gel and a preparation method and application thereof.

Background technique

Pineapple (Ananas comosus) is a tropical fruit with rich resources and unique flavor. It is deeply loved by the public. Its main production areas are concentrated in China, Thailand, Brazil, Mexico, the Philippines and Malaysia. The annual output of pineapple in the world is about 16-19 million tons, and the annual output in my country is about more than 2 million tons. Most pineapples are eaten fresh, or processed into canned pineapple, jam, salad, cocktail accessories, etc., and used as raw materials for the extraction of bromelain. During the processing of pineapple products, pineapple pomace occupies 30-42% of the pineapple processing waste, which is usually discarded as a by-product of processing, which pollutes the environment and causes waste of resources. Therefore, how to fully utilize and process pineapple pomace is of great significance to promote the high value of pineapple industry and environmental protection. Studies have found that pineapple pomace is mainly composed of cellulose, hemicellulose, lignin and pectin, and the dry weight content of cellulose reaches 22%. Making full use of these cellulose is an important entry point for the high value of pineapple pomace, but At present, there are relatively few studies on the high-value utilization of pineapple pomace cellulose.

As a natural raw material for hydrogel preparation, cellulose has better biocompatibility, degradability and non-toxicity than other synthetic polymers.

Kaolin (kaolin) is a hydrophilic layered silicate clay mineral material, which has the characteristics of large specific surface area, low price and easy availability. It can be well polymerized with organic monomers and absorb various ions and impurities from the surrounding medium. .

Sepia ink is mainly composed of melanin and proteoglycan, in which melanin can effectively adsorb heavy metal ions such as Cu ^{2 +} , Fe ³⁺ , Pb ²⁺ and Cd ²⁺ , and sepia ink is usually discarded in the aquatic product market.

Hydrogel is a multi-component system composed of a hydrophilic polymer three-dimensional network and water, which can absorb and retain a large amount of water but is insoluble in water. Due to the excellent hydrophilicity, biocompatibility, permeability, and high swelling rate of hydrogels, hydrogels have attracted extensive attention in the fields of sewage treatment, food packaging, medical materials, sensors, and drug release.

Therefore, it is of great significance to study the preparation of new hydrogels based on pineapple pomace cellulose and kaolin and squid ink as additives.

Contents of the invention

The primary purpose of the present invention is to provide a kind of hydrogel prepared from pineapple pomace cellulose, kaolin and squid ink as raw materials and a preparation method thereof.

Another object of the present invention is to provide the application of the hydrogel prepared by the above preparation method—as an adsorbent in wastewater treatment.

The object of the present invention is achieved through the following technical solutions:

A kind of preparation method of pineapple pomace cellulose-g-acrylic acid/kaolin/squid ink gel, specifically comprises the following steps:

(1) Preparation of pineapple pomace cellulose

Fresh pineapple peels are washed, beaten, dried, crushed, and sieved to obtain dry pineapple peel powder, mixed with distilled water, heated in a water bath, and the filter residues are collected for bleaching, then filtered, washed, and dried to obtain pineapple peels The crude product of slag cellulose, the crude product of pineapple peel cellulose is subjected to alkaline treatment, then filtered, washed, dried, and sieved to obtain Pineapple peel cellulose (PPC);

(2) Preparation of squid ink

Dissect the fresh squid and take out the ink sac, separate and squeeze out the ink, soak in distilled water, then centrifuge, dry, grind, and sieve to obtain sepia ink;

(3) Preparation of the hydrogel

Mix the pineapple peel cellulose with the ionic liquid, stir while heating to dissolve the pineapple peel cellulose evenly, add the initiator after cooling, continue stirring, add acrylic acid and cross-linking agent for graft modification, and then add kaolin Continue stirring with squid ink to react, after cooling, soak and wash in distilled water, remove unreacted substances and ionic liquid, and obtain pineapple pomace cellulose hydrogel (PPCH), that is, the hydrogel after freeze-drying.

Further, in the step (1), the pineapple skin dregs are washed and then dried at 50-60° C. for 24-36 hours; the pulverization adopts a Chinese herbal medicine pulverizer, and the mesh size of the sieve is 80-100 mesh.

Further, in step (1), the mixing ratio of the pineapple skin residue and distilled water is 1: (20-25) g/mL; the heating temperature in the water bath is 70-80°C, and the heating time in the water bath is 2-3h .

Further, the bleaching treatment described in step (1) is: using sodium chlorite solution with a mass fraction of 7.5-8.0% as bleaching agent, the solid-liquid ratio is 1: (15-20) g/mL, and using hydrochloric acid solution Adjust the pH of the solution to 3.8-4.0, and bleach for 2-4 hours at 70-80°C.

Further, the washing and drying after bleaching described in step (1): the washing refers to washing with distilled water to neutrality, and then washing 3-5 times with an ethanol solution with a volume fraction of 95%; the drying is Air-dry at room temperature for 2-3 hours, then dry at 50-60°C for 18-20 hours.

Further, the lye treatment described in step (1) is as follows: a sodium hydroxide solution with a mass fraction of 10-12% is used as the lye, the ratio of material to liquid is 1: (15-20) g/mL, and the mixture is stirred at room temperature The reaction is 10-12h, and the stirring speed is 300-500rpm.

Further, the washing and drying conditions after the lye treatment in step (1) are the same as those after the bleaching treatment, and the sieve mesh is 80-100 mesh.

Further, in step (2), the fresh squid is tiger squid; the soaking time is 16-20h, the solid-liquid ratio is 1:(20-30) g/mL, and the soaking temperature is 4-8°C.

Further, the centrifugal speed in step (2) is 4000-5000r/min, and the centrifugation time is 20-30min.

Further, in step (2), the drying temperature is 50-60° C., and the drying time is 16-20 hours; the mesh size of the sieving is 80-100 mesh.

Further, the ionic liquid described in step (3) is [BMIm]Cl (1-butyl-3-methylimidazole chloride), and the ratio of pineapple pomace cellulose and ionic liquid is 1:(40-50 ) g/g.

Further, in the step (3), the heating temperature of stirring and heating after mixing is 80-100° C., the heating time is 3-5 hours, and the stirring speed is 300-500 rpm.

Further, in step (3), the initiator is ammonium persulfate in an amount of 1.5-2.5% of the total mass of pineapple pomace cellulose and acrylic acid; the crosslinking agent is N,N-methylenebis Acrylamide, the consumption is 0.5-1.0% of the total mass of pineapple pomace cellulose and acrylic acid; the degree of neutralization of the acrylic acid is 60-80% (regulating with a mass fraction of 40% sodium hydroxide solution), and the consumption is the same as that of pineapple peel The ratio of slag cellulose mass is (4-6):1.

Further, in step (3), the cooling temperature before adding the initiator is 50-60°C; the time for continuing stirring is 10-20min; the reaction temperature of the graft modification is 60-80°C, The reaction time is 1-2h, and the stirring speed is 300-500rpm.

Further, in step (3), the reaction temperature after adding squid ink and kaolin is 60-80°C, the reaction time is 1-3h, and the stirring speed is 300-500rpm; The ratio of cellulose mass is (1-4):10; the ratio of the amount of squid ink added to the mass of pineapple pomace cellulose is (2-6):10.

Further, in step (3), the cooling after adding kaolin and squid ink for reaction refers to cooling to room temperature; the distilled water soaking and washing refers to changing the distilled water every 8-12h for 4 consecutive days.

Further, the freeze-drying in step (3) is drying at -(55-60)°C for 36-40 hours.

A novel hydrogel of pineapple pomace cellulose-g-acrylic acid/kaolin/sepia ink prepared by the above preparation method.

Application of the pineapple pomace cellulose-g-acrylic acid/kaolin/sepia ink novel hydrogel in the field of waste water treatment and adsorption materials.

Compared with prior art, the beneficial effect of the present invention is:

(1) The cellulose used for the preparation of the hydrogel in the present invention is derived from pineapple peel residues of agricultural production waste, which is abundant and easy to obtain. However, the ionic liquid is used to dissolve the cellulose, the reaction conditions are mild, the ecology is environmentally friendly, and it conforms to the characteristics of green chemistry.

(2) The present invention prepares hydrogel while carrying out acrylic acid grafting modification to pineapple pomace cellulose, and process operation is simple, and equipment requirement is low; Grafting acrylic acid makes hydrogel have pH responsiveness and good swelling performance, The application of the hydrogel is enriched.

(3) The present invention utilizes kaolin and squid ink to improve the application performance of pineapple peel residue cellulose hydrogel. Kaolin is cheap and can absorb various ions and impurities; while squid ink is usually discarded in the aquatic product market, but it can effectively absorb heavy metals ; These characteristics can make the prepared hydrogel have the application value of sewage treatment.

Description of drawings

Fig. 1 is the FT-IR spectrum of the hydrogel (PPCH-1) and pineapple pomace cellulose (PPC), cuttlefish ink, kaolin prepared by embodiment 1;

Fig. 2 is the XRD diffraction pattern of the hydrogel (PPCH-2) that embodiment 2 prepares and pineapple pomace cellulose (PPC);

Fig. 3 is the TG curve figure of the hydrogel (PPCH-3) that embodiment 3 prepares and pineapple pomace cellulose (PPC);

Fig. 4a is the SEM picture of hydrogel PPCH-4 in embodiment 4;

Fig. 4 b is the SEM picture of pineapple pomace cellulose PPC in embodiment 4;

Fig. 5 is the swelling performance and the methylene blue adsorption capacity of the hydrogels (PPCH-1, PPCH-2, PPCH-3 and PPCH-4) prepared in Examples 1-4.

Detailed ways

The present invention will be further illustrated and described below in conjunction with the accompanying drawings and examples, but the embodiments of the present invention are not limited thereto.

Example 1

(1) The pineapple pomace is washed, beaten, dried at 50°C for 36 hours, pulverized and sieved under 80 mesh to obtain pineapple pomace powder;

(2) Mix pineapple peel residue powder with distilled water at a solid-liquid ratio of 1:20g/mL, heat in a water bath at 70°C for 2 hours, and collect the filter residue after filtration for bleaching treatment. Use sodium chlorite solution with a mass fraction of 7.5% as the bleaching agent, the solid-liquid ratio is 1:15g/mL, adjust the pH value of the solution to 3.8 with 4mol/L hydrochloric acid solution, and bleach at 70°C for 2 hours;

(3) Collect the insoluble matter after the bleaching treatment by filtration, wash with distilled water to neutrality and then wash 3 times with ethanol solution with a volume fraction of 95%, air-dry at room temperature for 2 hours, and dry at 50° C. for 18 hours to obtain the crude pineapple pomace cellulose;

(4) Mix the crude pineapple pomace cellulose with 10% sodium hydroxide solution, the ratio of solid to liquid is 1:15g/mL, stir and react at room temperature for 10h, the stirring speed is 300rpm, filter and collect the filter residue, wash with distilled water After reaching neutrality, wash 3 times with ethanol solution with a volume fraction of 95%, air-dry at room temperature for 2 hours, dry at 50°C for 18 hours, and sieve through 80 mesh to obtain pineapple pomace cellulose;

(5) Preparation process of squid ink: dissect the fresh tiger squid, take out the ink sac, separate and extrude the ink, soak in distilled water for 20h at 4°C and the ratio of solid to liquid 1:20g/mL, centrifuge at 4000r/min for 20min, and precipitate The product was dried at 50°C for 16 hours, and after grinding, it was passed through an 80-mesh sieve to obtain squid ink;

(6) Add 8 g of ionic liquid [BMIm]Cl to 0.2 g of pineapple pomace cellulose, heat and stir at 80°C for 5 hours at a stirring speed of 300 rpm, add 0.015 g of initiator ammonium persulfate after cooling to 50°C, continue stirring for 10 minutes, and add 0.8g of acrylic acid with a degree of 60% and 0.005g of cross-linking agent N,N-methylenebisacrylamide were stirred and reacted at 60°C for 1h at a stirring speed of 300rpm, then 0.02g of kaolin and 0.04g of squid ink were added, and the Continue to stir at ℃ for 1 hour, and the stirring speed is 300rpm. After the reaction is completed, wait for the mixture to cool to room temperature, add distilled water to soak for 4 days, replace the distilled water every 8 hours, and then perform freeze-drying. The temperature of freeze-drying is -55°C, and the drying time is 36 hours The hydrogel PPCH-1 was obtained.

Fig. 1 is the FT-IR spectrum of hydrogel (PPCH-1) and pineapple pomace cellulose (PPC), squid ink, kaolin prepared in embodiment 1. The peak around 3400cm ^-1 in PPCH-1 and PPC is the characteristic absorption peak of -OH, the peak around 1400cm ^-1 is the CH bending vibration absorption peak, and the 1053cm ^-1 is the COC stretching vibration absorption peak. These are natural cellulose characteristic absorption peaks. In kaolin, 1088cm ^-1 and 907cm ^-1 are Si-O stretching vibration absorption peaks, and 792cm ^-1 and 564cm ^-1 are Si-O-Al stretching vibration and Si-O-Al bending vibration absorption peaks, respectively. The 3224, 1578, 1368cm ^-1 in squid ink are OH and NH stretching vibration absorption peaks, COO-ionization and C=O double bond absorption peaks, and CN stretching vibration absorption peaks respectively. These are the characteristic absorption peaks of melanin in squid ink. Compared with PPC, PPCH-1 has a new absorption peak at 1720cm ^-1 , which is C=O stretching vibration absorption peak, which is caused by grafting acrylic acid to cellulose from pineapple pomace. The absorption peak at 3400cm ^-1 in PPC becomes broad, which may be related to the addition of squid ink. 565cm ^-1 in PPCH-1 is the Si-O-Al bending vibration absorption peak, which is caused by the embedding of kaolin.

Example 2

(1) The pineapple pomace is washed, beaten, dried at 55°C for 24 hours, pulverized and sieved under 100 mesh to obtain pineapple pomace powder;

(2) Mix pineapple peel residue powder with distilled water at a solid-liquid ratio of 1:25g/mL, heat in a water bath at 75°C for 3 hours, and collect the filter residue after filtration for bleaching treatment. Use sodium chlorite solution with a mass fraction of 8.0% as the bleaching agent, the ratio of solid to liquid is 1:20g/mL, adjust the pH value of the solution to 3.9 with 4mol/L hydrochloric acid solution, and bleach at 75°C for 3h;

(3) Collect the insoluble matter after the bleaching treatment by filtration, wash with distilled water to neutrality and then wash with ethanol solution with a volume fraction of 95% for 4 times, air-dry at room temperature for 3 hours, and dry at 55°C for 20 hours to obtain the crude pineapple pomace cellulose;

(4) Mix the crude pineapple pomace cellulose with 10% sodium hydroxide solution, the ratio of solid to liquid is 1:20g/mL, stir and react at room temperature for 12h, the stirring speed is 400rpm, filter and collect the filter residue, wash with distilled water After reaching neutrality, wash with 95% ethanol solution for 3 times, air-dry at room temperature for 3 hours, dry at 55°C for 18 hours, and sieve through 100 mesh to obtain pineapple pomace cellulose;

(5) Preparation process of squid ink: dissect the fresh tiger squid, take out the ink sac, separate and squeeze out the ink, soak in distilled water for 18h at 5°C and the ratio of solid to liquid 1:25g/mL, centrifuge at 4500r/min for 25min, and precipitate Dry at 55°C for 18 hours, grind and pass through a 100-mesh sieve to obtain squid ink;

(6) Add 9 g of ionic liquid [BMIm]Cl to 0.2 g of pineapple pomace cellulose, heat and stir at 90 ° C for 4 h at a stirring speed of 400 rpm, add 0.024 g of initiator ammonium persulfate after cooling to 55 ° C, continue stirring for 15 min, and add 1.0g of acrylic acid with a degree of 70% and 0.0096g of cross-linking agent N,N-methylenebisacrylamide were stirred and reacted at 60°C for 3h at a stirring speed of 400rpm, then 0.05g of kaolin and 0.04g of squid ink were added, and the Continue to stir at ℃ for 1.5h, and the stirring speed is 400rpm. After the reaction is completed, wait for the mixed solution to cool to room temperature, add distilled water to soak for 4d, replace the distilled water every 8h, and then perform freeze-drying. The temperature of freeze-drying is -58°C and the drying time is After 38 hours, the hydrogel PPCH-2 was obtained.

Fig. 2 is the XRD diffraction pattern of hydrogel PPCH-2 and pineapple pomace cellulose PPC in embodiment 2. PPC has a strong diffraction peak at 21.8°, and the intensity of the diffraction peaks at 15.3° and 34.6° is weaker, which is formed by the crystallization of pineapple pomace cellulose itself. However, in the hydrogel PPCH-2, the intensity of the original diffraction peaks in PPC weakened, the diffraction peaks at 15.3° and 34.6° almost disappeared, and a new weaker diffraction peak appeared at 26.4°, these All indicated that the original crystal structure of pineapple pomace cellulose was destroyed and the crystallinity decreased obviously during the process of modification and preparation of hydrogel.

Example 3

(1) The pineapple pomace is washed, beaten, dried at 55°C for 30 hours, pulverized and sieved under 100 mesh to obtain pineapple pomace powder;

(2) Mix pineapple peel residue powder with distilled water at a solid-liquid ratio of 1:20g/mL, heat in a water bath at 80°C for 3 hours, and collect the filter residue after filtration for bleaching treatment. Use sodium chlorite solution with a mass fraction of 7.5% as the bleaching agent, the ratio of solid to liquid is 1:20g/mL, adjust the pH value of the solution to 3.9 with 4mol/L hydrochloric acid solution, and bleach at 80°C for 3h;

(3) Collect the insoluble matter after the bleaching treatment by filtration, wash with distilled water to neutrality and then wash 5 times with an ethanol solution with a volume fraction of 95%, air-dry at room temperature for 3 hours, and dry at 55° C. for 18 hours to obtain the crude pineapple pomace cellulose;

(4) Mix the crude pineapple pomace cellulose with 10% sodium hydroxide solution, the ratio of solid to liquid is 1:15g/mL, stir and react at room temperature for 10h, the stirring speed is 500rpm, filter and collect the filter residue, wash with distilled water After reaching neutrality, wash 3 times with ethanol solution with a volume fraction of 95%, air-dry at room temperature for 3 hours, dry at 55°C for 20 hours, and sieve through 80 mesh to obtain pineapple pomace cellulose;

(5) Preparation process of squid ink: dissect the fresh tiger squid, take out the ink sac, separate and extrude the ink, soak in distilled water for 20h at 8°C and a solid-liquid ratio of 1:20g/mL, centrifuge at 5000r/min for 20min, and precipitate Dry at 60°C for 16 hours, and pass through a 100-mesh sieve to obtain squid ink after grinding;

(6) Add 10 g of ionic liquid [BMIm]Cl to 0.2 g of pineapple pomace cellulose, heat and stir at 100°C for 3 hours at a stirring speed of 500 rpm, add 0.035 g of initiator ammonium persulfate after cooling to 60°C, continue stirring for 20 minutes, and add 1.2g of acrylic acid with a degree of 80% and 0.014g of cross-linking agent N,N-methylenebisacrylamide were stirred at 60°C for 3h at a stirring speed of 400rpm, then 0.05g of kaolin and 0.08g of squid ink were added, and the Continue to stir at ℃ for 1 hour, and the stirring speed is 500rpm. After the reaction is completed, wait for the mixture to cool to room temperature, add distilled water to soak for 4 days, replace the distilled water every 8 hours, and then perform freeze-drying. The temperature of freeze-drying is -60℃ and the drying time is 40 hours. , to obtain the hydrogel PPCH-3.

Fig. 3 is the TG curve graph of hydrogel PPCH-3 and pineapple pomace cellulose PPC in embodiment 3. It can be seen from Figure 3 that the initial decomposition temperature of hydrogel PPCH-3 is lower than that of PPC, indicating that during the modification of pineapple peel cellulose and the preparation of hydrogel, the intramolecular and intermolecular hydrogen bonds of pineapple peel cellulose Destroyed, the thermal stability is reduced. However, PPC has a higher weight loss rate than PPCH-3. When the temperature reaches 500 ° C, the weight loss rate of PPC is about 80%, while that of PPCH-3 is only 60%, indicating that the degradation degree of hydrogel PPCH-3 is relatively low. Low.

Example 4

(1) The pineapple pomace is washed, beaten, dried at 60°C for 24 hours, pulverized and sieved under 80 mesh to obtain pineapple pomace powder;

(2) Mix pineapple peel residue powder with distilled water at a solid-liquid ratio of 1:20 g/mL, heat in a water bath at 80°C for 2 hours, and collect the filter residue after filtration for bleaching treatment. Use sodium chlorite solution with a mass fraction of 7.5% as the bleaching agent, the ratio of solid to liquid is 1:15g/mL, adjust the pH value of the solution to 4.0 with 4mol/L hydrochloric acid solution, and bleach at 75°C for 4 hours;

(3) Collect the insoluble matter after the bleaching treatment by filtration, wash with distilled water to neutrality and then wash 3 times with an ethanol solution with a volume fraction of 95%, air-dry at room temperature for 3 hours, and dry at 60° C. for 18 hours to obtain the crude pineapple pomace cellulose;

(4) Mix the crude pineapple pomace cellulose with 10% sodium hydroxide solution, the ratio of solid to liquid is 1:20g/mL, stir and react at room temperature for 12h, the stirring speed is 400rpm, filter and collect the filter residue, wash with distilled water After reaching neutrality, wash 3 times with ethanol solution with a volume fraction of 95%, air-dry at room temperature for 3 hours, dry at 55°C for 18 hours, and sieve through 100 mesh to obtain pineapple pomace cellulose;

(5) Preparation process of squid ink: dissect the fresh tiger squid, take out the ink sac, separate and extrude the ink, soak in distilled water for 18h at 4°C and the ratio of solid to liquid 1:30g/mL, centrifuge at 4500r/min for 30min, and precipitate Dry at 50°C for 20 hours, grind and pass through a 100-mesh sieve to obtain squid ink;

(6) Add 8 g of ionic liquid [BMIm]Cl to 0.2 g of pineapple pomace cellulose, heat and stir at 90 ° C for 3 h at a stirring speed of 400 rpm, add 0.025 g of initiator ammonium persulfate after cooling to 60 ° C, continue stirring for 15 min, and add 0.8g of acrylic acid with a degree of 70% and 0.005g of cross-linking agent N,N-methylenebisacrylamide were stirred and reacted at 80°C for 2h at a stirring speed of 300rpm, then 0.08g of kaolin and 0.04g of squid ink were added, and the Continue to stir for 2 hours at ℃, the stirring speed is 500rpm. After the reaction is completed, wait for the mixture to cool to room temperature, add distilled water to soak for 4 days, replace the distilled water every 8 hours, and then freeze-dry. The temperature of freeze-drying is -55℃ and the drying time is 36 hours. , to obtain the hydrogel PPCH-4.

Figure 4a is the SEM image of the hydrogel PPCH-4 in Example 4, and Figure 4b is the SEM image of the pineapple pomace cellulose PPC in Example 4. It can be seen from the figure that after the original rod-like structure of the pineapple pomace cellulose in Figure 4a is modified and hydrogel is prepared, the hydrogel PPCH-4 in Figure 4b obtained has a layered planar structure, and its surface distribution More granular matter is a mixture of squid ink and kaolin, indicating that squid ink and kaolin have been evenly distributed in the hydrogel.

Example 5

The hydrogels prepared in Examples 1-4 were used to study their swelling properties and their ability to absorb methylene blue.

Accurately weigh 25 mg of the hydrogels prepared in Examples 1 to 4, place them in beakers filled with 100 mL of distilled water, swell at room temperature for 24 hours, take out the hydrogels, blot the hydrogels with filter paper to show moisture, and weigh The mass after hydrogel swelling is calculated to obtain the swelling rate;

Accurately weigh 25 mg of the hydrogel prepared in Examples 1 to 4, respectively immerse in 40 mL of the methylene blue solution with a concentration of 100 mg/L, and after adsorption at room temperature for 72 hours, take out the hydrogel, measure the concentration of the methylene blue solution in the solution, and calculate Adsorption capacity of hydrogel to methylene blue;

The swelling properties of the tested hydrogel and the adsorption capacity for methylene blue are shown in Figure 5. It can be seen from Figure 5 that the swelling abilities of hydrogels PPCH-1, PPCH-2, PPCH-3, and PPCH-4 in distilled water at room temperature are 25.41, 22.14, 24.91, and 24.16 g/g, respectively, and the swelling performance is good, among which The swelling capacity of PPCH-1 is slightly higher than that of the other three. The results of methylene blue adsorption experiments show that the hydrogels PPCH-1, PPCH-2, PPCH-3 and PPCH-4 all have good adsorption capacity for methylene blue, among which PPCH-1 is slightly higher than the other three kinds, with an adsorption capacity of 153.85 mg /g, which is related to the better swelling performance of PPCH-1, indicating that this type of hydrogel has good adsorption performance for cationic dyes in wastewater, and can be used as an adsorbent in wastewater treatment.

The above-mentioned embodiments are merely examples for illustrating the present invention, but the present invention is not limited to the above-described embodiments. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention within the knowledge of those skilled in the art shall be considered as the scope of protection of the present invention.

Claims (3)

1. a preparation method of pineapple pomace cellulose-g-acrylic acid/kaolin/squid ink gel, is characterized in that, specifically comprises the following steps: (1) Preparation of pineapple skin dregs cellulose: fresh pineapple skin dregs are washed, beaten, dried, crushed, and sieved to obtain pineapple skin dregs dry powder, which is mixed with distilled water, heated in a water bath, and the filter residues are collected for bleaching treatment , then filtering, washing, and drying to obtain the crude pineapple pomace cellulose, and then through alkali treatment, filtering, washing, drying, and sieving to obtain the pineapple pomace cellulose; (2) Preparation of squid ink: dissect the fresh squid, take out the ink sac, separate and squeeze out the ink, soak in distilled water, then centrifuge, dry, grind, and sieve to obtain squid ink; (3) Preparation of the hydrogel: mix the pineapple peel cellulose with the ionic liquid, stir while heating to dissolve the pineapple peel cellulose evenly, add the initiator after cooling, continue stirring, add acrylic acid, Carry out grafting modification with the joint agent, then add kaolin and squid ink to continue stirring to react, after cooling, distilled water soaks and washes, and freeze-dries to obtain the hydrogel; In step (1), the mixing ratio of the pineapple peel dry powder and distilled water is 1:(20-25) g/mL; the temperature of the water bath heating is 70-80°C, and the water bath heating time is 2-3h; In step (1), the bleaching treatment uses sodium chlorite solution with a mass fraction of 7.5-8.0% as the bleaching agent, the solid-liquid ratio is 1: (15-20) g/mL, and the pH is adjusted with hydrochloric acid solution to 3.8-4.0, bleaching treatment at 70-80°C for 2-4h; the lye treatment is to use a sodium hydroxide solution with a mass fraction of 10-12% as lye, and the ratio of solid to liquid is 1:(15-20)g /mL, stir at room temperature for 10-12h; In step (2), the fresh squid is tiger squid; the soaking time is 16-20 hours, the solid-liquid ratio is 1:(20-30) g/mL, and the soaking temperature is 4-8°C; In step (3), the ionic liquid is 1-butyl-3-methylimidazole chloride, and the ratio of pineapple pomace cellulose to the ionic liquid is 1: (40-50) g/g; while heating The heating temperature while stirring is 80-100°C, and the heating time is 3-5h; In step (3), the initiator is ammonium persulfate in an amount of 1.5-2.5% of the total mass of pineapple pomace cellulose and acrylic acid; the crosslinking agent is N,N-methylenebisacrylamide in an amount of It is 0.5-1.0% of the total mass of pineapple peel cellulose and acrylic acid; the degree of neutralization of the acrylic acid is 60-80%, and the ratio of the amount to the quality of pineapple peel cellulose is (4-6):1; In step (3), the cooling temperature before the addition of the initiator is 50-60°C; the initiator is added after the cooling, and the stirring time is continued for 10-20 minutes; the reaction temperature of the graft modification is 60-60°C. 80°C, the reaction time is 1-2h; In step (3), the reaction temperature after adding kaolin and squid ink is 60-80°C, and the reaction time is 1-3h; the ratios of the added amount of kaolin and squid ink to the mass of pineapple pomace cellulose are (1 -4): 10 and (2-6): 10; the freeze-drying is -(55-60)°C for 36-40h. 2. a pineapple pomace cellulose-g-acrylic acid/kaolin/squid ink gel obtained by the preparation method claimed in claim 1. 3. the application of pineapple pomace cellulose-g-acrylic acid/kaolin/squid ink gel in waste water treatment or adsorption material field described in claim 2.