CN105817205A - A preparation method of nanocrystalline cellulose magnetic particles adsorbing heavy metal ions - Google Patents

Abstract

The present invention uses sycamore wood or willow wood as raw materials to prepare microcrystalline cellulose, then prepares nanocrystalline cellulose, and finally prepares nanocrystalline cellulose magnetic particles through graft modification, which has the characteristics of wide range of raw materials and low cost, and the prepared adsorbent Environmentally friendly and pollution-free, it can be used to adsorb various heavy metals such as lead, chromium, and copper in seafood soy sauce. It has large adsorption capacity, good effect, and has regeneration ability.

Description

A preparation method of nanocrystalline cellulose magnetic particles adsorbing heavy metal ions

technical field

The invention relates to the field of nanocrystalline cellulose composite materials, in particular to a method for preparing nanocrystalline cellulose magnetic particles for adsorbing heavy metal ions in seafood soy sauce.

Background technique

With the development of modern economy and the development and utilization of marine resources in the offshore area, a large amount of waste water and domestic sewage containing heavy metal ions are discharged into the sea, the heavy metal pollution in marine water has increased sharply, and the ecological environment has also suffered great damage. Heavy metal ions can be enriched and accumulated through the food chain. A large number of studies have shown that the heavy metal content of fish in seawater has seriously exceeded the standard.

Seafood soy sauce is made of super light soy sauce as the main ingredient, together with the essence of sea fish and shrimp refined by modern technology, it is rich in nutrition, rich in fragrance, fresh and sweet, and has a long-lasting seafood flavor. And because the heavy metal content of sea fish and shrimp seriously exceeds the standard, the heavy metal content in the seafood soy sauce that causes preparation is also relatively high.

Heavy metals have certain toxicity. For example, cadmium, when the environment is polluted, cadmium can enter the human body through the food chain to enrich, destroy the sulfhydryl enzyme system in the body, affect tissue metabolism, cause damage to local tissue cells, and cause various inflammations and edema. Once absorbed into the blood, it will form cadmium protein in the human body, and then selectively accumulate in the liver, kidney and other tissues and organs, thereby damaging the functions of the liver, kidney and other organs. Copper is an essential trace element, but if it is taken in too much, it will cause digestive system disorders. Long-term excess may also lead to liver cirrhosis. After too much copper enters the human body, copper poisoning will occur. The network formed by copper and protein The compound is highly fat-soluble and easily reacts with enzymes and nucleic acids. After reacting with DNA, it can promote the malignant differentiation and growth of cells. Some studies believe that there is a positive correlation between the mortality rate of liver cancer and the copper content in the environment.

Due to the toxic effect of heavy metals, my country has set limits on the content of heavy metals in proteolysis solutions. The traditional removal methods of heavy metals in aqueous solution mainly include: chemical precipitation, ion exchange resin, adsorption and so on. The chemical precipitation method is one of the most widely used methods in the treatment of heavy metal pollution in wastewater. This method has a simple process, but requires the use of chemical precipitation agents. The ion exchange resin method has the advantages of large processing capacity, convenience and quickness, but its operation cost is high, the ion exchanger regeneration operation is complicated, and the residual porogen in the resin is easy to contaminate the proteolysis solution. Therefore, from the perspective of food safety, the above two methods are not suitable for the removal of heavy metal ions in proteolysis solution. The adsorption process is relatively simple, the adsorption capacity is large, and there are many kinds of adsorbents, such as activated carbon, attapulgite, diatomaceous earth, etc. are commonly used. There are many reports on the adsorption of heavy metal ions in solution by natural adsorption materials (such as chitosan, lignocellulose, etc.). From the perspective of the microstructure of natural lignocellulose, its molecular arrangement is directional and has the characteristics of crystals (called cellulose crystallization regions). Lignocellulose is often formed by covalent bonds with other macromolecules in plant tissues. Lignin-carbohydrate complexes, these microstructures may affect the adsorption capacity and adsorption selectivity in two aspects: (1) the existence of crystallization regions limits the diffusion of metal ions in solution to the inside of lignocellulose adsorbent particles, and the crystallization (2) Due to the presence of lignin-carbohydrate complexes, the surface area, pore volume, average pore radius and pore size distribution of lignocellulose adsorbent particles are not in the same range. The suitable range affects the adsorption selectivity and adsorption capacity. The above reasons lead to the fact that only in the solution system with a high concentration of metal ions, the natural lignocellulose exhibits efficient adsorption performance. The ionic strength of the solution has a great influence on the adsorption of metal ions in lignocellulose. When there is a high concentration of NaCl and other electrolytes in the solution, the adsorption capacity of the system will be reduced; therefore, the adsorption process of heavy metal ions in the marine protein hydrolyzate must also be considered Competitive adsorption of sodium chloride, amino acids, peptides, proteins. Existing research does not involve the adsorption and removal of heavy metal ions in salt-containing and amino acid, polypeptide, and protein solution systems. Therefore, how to improve the adsorption selectivity of porous lignocellulose, and then increase the adsorption capacity, is an urgent problem to be solved.

Contents of the invention

The purpose of the present invention is to provide a preparation method of nanocrystalline cellulose magnetic particles for adsorbing heavy metals in seafood soy sauce in order to solve the defect that heavy metal ions exceed the standard after the production of seafood soy sauce.

In order to achieve the above object, the present invention adopts the following technical solutions:

A method for preparing nanocrystalline cellulose magnetic particles that absorb heavy metal ions. The preparation method is to prepare nanocrystalline cellulose by acid hydrolysis of microcrystalline cellulose, and then prepare nanocrystalline cellulose magnetic particles through graft modification.

Preferably, the preparation method of microcrystalline cellulose is to use sycamore sawdust or willow sawdust as raw material, cook with distilled water at 95-100°C for 2-4h, then dry at 120-155°C for 10-12h, and crush through a 200-300 mesh sieve , after washing 2-3 times, dry at 140-160°C to obtain lignocellulose, then mix 1g lignocellulose: 35-50mL of 1.2-1.5mol/L hydrochloric acid at a solid-liquid ratio, and heat up to 60-70 After ultrasonic treatment at ℃ for 1-1.5h, filter with suction, wash the filter residue until neutral, soak it in 90-98wt% ethanol for 2-3h, then filter, dry the obtained filter residue to a water content of 5-10%, and then discharge and pulverize to obtain microcrystalline fiber white.

Preferably, the preparation method of nanocrystalline cellulose is to add microcrystalline cellulose and strongly acidic cation exchange resin to 1000 mL of deionized water at a mass ratio of 1:15-20, stir at 65-70°C, and ultrasonically treat for 1 -2.5h, filter out the cation exchange resin after catalytic hydrolysis, and separate the cellulose sample, and centrifuge the cellulose sample at 15000-20000r/min for 5-10min at high speed to obtain nanocrystalline cellulose. In this technical solution, since the existing preparation of nanocrystalline cellulose is mostly made by hydrolysis with strong acid solution, but because the recovery of strong acid solution is difficult, and it will pollute the environment, the present invention selects microcrystalline cellulose and strongly acidic cation exchange resin to prepare nanocrystalline cellulose.

Preferably, the preparation method of nanocrystalline cellulose magnetic particles is to prepare a nanocrystalline cellulose dispersion with a concentration of 25-50 mg/mL, and ultrasonically disperse it for 1-2 hours before use; in acetone with a liquid-solid ratio of 1 mL: 4-6 mg Add CDI, then add magnetic particles with 30-40% weight of CDI, react at room temperature for 3-5h, then add ethylenediamine with 1-2% volume of acetone, apply a magnetic field of 1.0-1.5T, continue to react for 2-3h, remove After the organic solvent is placed at 0-4°C for 3-5h to obtain magnetic nanoparticles; add CDI to methanol with a liquid-solid ratio of 1mL: 50-100mg, then add magnetic nanoparticles of the same quality as CDI, and add 1.0-1.5T magnetic field, react at room temperature for 2-3 hours, add nanocrystalline cellulose dispersion, continue to react for 3-5 hours, centrifuge, take the precipitate, vacuum dry and pulverize to obtain nanocrystalline cellulose magnetic particles.

Preferably, the nanocrystalline cellulose dispersion is that nanocrystalline cellulose is added to ethylene glycol or glycerol.

Preferably, the volume ratio of methanol to the nanocrystalline cellulose dispersion is 1:1, and the dropping rate of the nanocrystalline cellulose dispersion is 15-20 mL/min.

Preferably, the ultrasonic treatment is 60-80KHz ultrasonic waves.

Preferably, the ultrasonic treatment is 70-90KHz ultrasonic waves.

Preferably, the magnetic particles are iron oxide magnetic particles of 20-50 nm.

The beneficial effect of the present invention is that the present invention uses sycamore wood or willow wood as raw materials to prepare microcrystalline cellulose, then prepares nanocrystalline cellulose, and finally prepares nanocrystalline cellulose magnetic particles through graft modification, which has the characteristics of wide range of raw materials and low cost , the prepared adsorbent is green, environmentally friendly and pollution-free, and can be used to adsorb various heavy metals such as lead, chromium and copper in seafood soy sauce, with large adsorption capacity, good effect and regeneration ability.

Description of drawings

Fig. 1 is the scanning electron microscope picture prepared in embodiment 1.

detailed description

The following will clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Example 1

A preparation method for nanocrystalline cellulose magnetic particles adsorbing heavy metal ions, comprising the following steps:

The preparation method of microcrystalline cellulose is to use sycamore sawdust as raw material, cook with distilled water at 95°C for 2 hours, then dry at 120°C for 10 hours, pulverize through a 200-mesh sieve, wash twice, and then dry at 140°C to obtain lignocellulose. Then mix 1g lignocellulose with a solid-liquid ratio: 35mL of 1.2mol/L hydrochloric acid, heat up to 60°C for 1h, and then filter with suction at an ultrasonic frequency of 55KHz. , the obtained filter residue is dried to a water content of 5%, and then discharged and pulverized to obtain microcrystalline cellulose;

The preparation method of nanocrystalline cellulose is to add microcrystalline cellulose and strongly acidic cation exchange resin to 1000mL deionized water at a mass ratio of 1:15, stir at 65°C, and ultrasonically treat for 1h at an ultrasonic frequency of 60KHz to catalyze hydrolysis. After the completion, the cation exchange resin was filtered out, and the cellulose sample was separated, and the cellulose sample was centrifuged at 15,000 r/min for 5 minutes, and the nanocrystalline cellulose was obtained after precipitation and drying;

The preparation method of nanocrystalline cellulose magnetic particles is to add nanocrystalline cellulose to ethylene glycol, prepare a nanocrystalline cellulose dispersion with a concentration of 25mg/mL, and ultrasonically disperse it for 1 hour before use. The ultrasonic frequency is 70KHz; 1mL: Add CDI to 4mg of acetone, then add 20nm iron oxide magnetic particles with 30% weight of CDI, react at room temperature for 3h, then add ethylenediamine with 1% volume of acetone, add 1.0T magnetic field, continue to react for 2h, After removing the organic solvent, place it at 0°C for 3 hours to obtain magnetic nanoparticles; add CDI to methanol with a liquid-solid ratio of 1mL:50mg, then add magnetic nanoparticles of the same mass as CDI, apply a 1.0T magnetic field, and react at room temperature for 2 hours. Add nanocrystalline cellulose dispersion, the volume ratio of methanol to nanocrystalline cellulose dispersion is 1:1, the drop rate of nanocrystalline cellulose dispersion is 15mL/min, continue to react for 3h, centrifuge, take the precipitate, vacuum dry and pulverize, The nanocrystalline cellulose magnetic particles are obtained.

Example 2

A preparation method for nanocrystalline cellulose magnetic particles adsorbing heavy metal ions, comprising the following steps:

The preparation method of microcrystalline cellulose is to use sycamore sawdust as raw material, cook it with distilled water at 98°C for 3 hours, then dry it at 135°C for 11 hours, crush it through a 250 mesh sieve, wash it three times, and dry it at 150°C to obtain lignocellulose. Then mix 1g lignocellulose with a solid-liquid ratio: 40mL of 1.3mol/L hydrochloric acid, heat up to 65°C and ultrasonically treat for 1.2h, then filter with suction, wash the filter residue to neutral, soak it with 95wt% ethanol for 2.5h, and then filter to obtain The filter residue was dried to a water content of 8%, and then discharged and pulverized to obtain microcrystalline cellulose;

The preparation method of nanocrystalline cellulose is to add microcrystalline cellulose and strongly acidic cation exchange resin into 1000mL deionized water at a mass ratio of 1:18, stir at 68°C, and ultrasonically treat for 2 hours at an ultrasonic frequency of 70KHz to catalyze hydrolysis. After the completion, the cation exchange resin was filtered out, and the cellulose sample was separated, and the cellulose sample was centrifuged at 18,000 r/min for 7 minutes to obtain nanocrystalline cellulose;

The preparation method of nanocrystalline cellulose magnetic particles is to add nanocrystalline cellulose to ethylene glycol or glycerol, prepare a nanocrystalline cellulose dispersion with a concentration of 30 mg/mL, and ultrasonically disperse for 1.5 hours before use. The ultrasonic frequency is 80KHz ;Add CDI to acetone with a liquid-solid ratio of 1mL:5mg, then add 30nm iron oxide magnetic particles with a weight of 35% of CDI, react at room temperature for 4 hours, then add ethylenediamine with acetone volume of 1.5%, and apply a magnetic field of 1.2T , continue to react for 2.5h, remove the organic solvent and place it at 3°C for 4h to obtain magnetic nanoparticles; add CDI to methanol with a liquid-solid ratio of 1mL:70mg, then add magnetic nanoparticles of the same quality as CDI, and add 1.2T of Magnetic field, react at room temperature for 2.5h, add nanocrystalline cellulose dispersion, the volume ratio of methanol to nanocrystalline cellulose dispersion is 1:1, the drop rate of nanocrystalline cellulose dispersion is 18mL/min, continue to react for 4h, centrifuge , the precipitate was vacuum-dried and pulverized to obtain nanocrystalline cellulose magnetic particles.

Example 3

A preparation method for nanocrystalline cellulose magnetic particles adsorbing heavy metal ions, comprising the following steps:

The preparation method of microcrystalline cellulose is to use sycamore wood chips or willow wood chips as raw materials, cook them with distilled water at 100°C for 4 hours, then dry them at 155°C for 12 hours, crush them through a 300-mesh sieve, wash them three times, and dry them at 160°C to obtain woody cellulose. Cellulose, then mix 1g lignocellulose with 50mL of 1.5mol/L hydrochloric acid at a material-to-liquid ratio, raise the temperature to 70°C and ultrasonically treat for 1.5h, then filter with suction, wash the filter residue until it is neutral, soak it in 98wt% ethanol for 3h, and then filter , the obtained filter residue is dried to a water content of 10%, and then discharged and pulverized to obtain microcrystalline cellulose;

The preparation method of nanocrystalline cellulose is to add microcrystalline cellulose and strongly acidic cation exchange resin into 1000mL deionized water at a mass ratio of 1:20, stir at 70°C, and ultrasonically treat for 2.5h at an ultrasonic frequency of 80KHz to catalyze After the hydrolysis, the cation exchange resin was filtered out, and the cellulose sample was separated, and the cellulose sample was centrifuged at 20000r/min for 10min to obtain nanocrystalline cellulose;

The preparation method of nanocrystalline cellulose magnetic particles is to add nanocrystalline cellulose to ethylene glycol or glycerol, prepare a nanocrystalline cellulose dispersion with a concentration of 50 mg/mL, and ultrasonically disperse for 2 hours before use. The ultrasonic frequency is 90KHz; Add CDI to acetone with a liquid-solid ratio of 1mL: 6mg, then add 50nm iron oxide magnetic particles with a weight of 40% of CDI, react at room temperature for 5 hours, then add ethylenediamine with acetone volume of 2%, and apply a magnetic field of 1.5T. Continue the reaction for 3 hours, remove the organic solvent and place it at 4°C for 5 hours to obtain magnetic nanoparticles; add CDI to methanol with a liquid-solid ratio of 1mL:100mg, then add magnetic nanoparticles of the same quality as CDI, and apply a magnetic field of 1.5T. React at room temperature for 3 hours, add nanocrystalline cellulose dispersion, the volume ratio of methanol to nanocrystalline cellulose dispersion is 1:1, the drop rate of nanocrystalline cellulose dispersion is 20mL/min, continue to react for 5 hours, centrifuge, and take the precipitate Vacuum drying and crushing to obtain nanocrystalline cellulose magnetic particles.

Fig. 1 is a scanning electron micrograph of nanocrystalline cellulose magnetic particles prepared in Example 1 of the present invention.

Buy seafood soy sauce from the market, measure the content of lead, chromium, copper ion contained in it and see Table 1, use the nanocrystalline cellulose magnetic particle prepared by embodiment 1-3 to adsorb this seafood soy sauce, detect the lead contained in it again , chromium, copper ion content, see Table 1.

Table 1. Metal ion content and detection results

Pb (μg/mL) Cr(μg/mL) Cu(μg/mL) Original content 0.371 0.059 0.012 Example 1 0.002 0.001 0.003 Example 2 0.003 0.002 0.001 Example 3 0.007 0.002 0.001

It can be seen from Table 1 that the nanocrystalline cellulose magnetic particles prepared by the present invention have large adsorption capacity and good effect on heavy metals in seafood soy sauce.

It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should fall within the protection scope of the appended claims of the present invention.

Claims (9)

1. the preparation method of the nano-crystal fibrin magnetic particle of an Adsorption of Heavy Metal Ions, it is characterised in that described preparation method, for prepared by microcrystalline Cellulose acidolysis nano-crystal cellulose, then prepares nano-crystal fibrin magnetic particle by graft modification.

nullThe preparation method of the nano-crystal fibrin magnetic particle of a kind of Adsorption of Heavy Metal Ions the most according to claim 1，It is characterized in that，The preparation method of microcrystalline Cellulose is to consider to be worth doing as raw material with Firmiana platanifolia (Linn. f.) Marsili wood flour or willow，With drying 10-12h after 95-100 DEG C of steaming and decocting 2-4h of distilled water at 120-155 DEG C，Pulverized 200-300 mesh sieve，Dry at 140-160 DEG C after washing 2-3 time and obtain lignocellulose，Then the mixed in hydrochloric acid being the 1.2-1.5mol/L of 1g lignocellulose: 35-50mL with solid-liquid ratio，It is warming up to sucking filtration after 60-70 DEG C of supersound process 1-1.5h，Filtering residue filters with after 90-98wt% soak with ethanol 2-3h after being washed till neutrality，The filter residue and drying obtained is pulverized to discharging after water content 5-10%，Obtain microcrystalline Cellulose.

The preparation method of the nano-crystal fibrin magnetic particle of a kind of Adsorption of Heavy Metal Ions the most according to claim 1 and 2, it is characterized in that, the preparation method of nano-crystal cellulose is with the mass ratio of 1:15-20 by microcrystalline Cellulose and storng-acid cation exchange resin, join in 1000mL deionized water, stirring, supersound process 1-2.5h at 65-70 DEG C, cation exchange resin is leached after catalyzing hydrolysis is complete, and isolate cellulose sample, by cellulose sample at 15000-20000r/min high speed centrifugation 5-10min, obtain nano-crystal cellulose.

The preparation method of the nano-crystal fibrin magnetic particle of a kind of Adsorption of Heavy Metal Ions the most according to claim 1, it is characterized in that, the preparation method of nano-crystal fibrin magnetic particle be configuration concentration be the nano-crystal cellulose dispersion liquid of 25-50mg/mL, standby after ultrasonic disperse 1-2h；CDI is added in the acetone that liquid-solid ratio is 1mL:4-6mg, add the magnetic particle of CDI weight 30-40%, 3-5h is reacted under room temperature, add the ethylenediamine of acetone volume 1-2%, the magnetic field of additional 1.0-1.5T, continue reaction 2-3h, remove 3-5h at organic solvent is placed on 0-4 DEG C and obtain magnetic nano-particle；CDI is added in the methanol that liquid-solid ratio is 1mL:50-100mg, add and the magnetic nano-particle of CDI equal in quality, the magnetic field of additional 1.0-1.5T, room temperature reaction 2-3h, add nano-crystal cellulose dispersion liquid, continue reaction 3-5h, centrifugal, take precipitation vacuum drying to pulverize, obtain nano-crystal fibrin magnetic particle.

The preparation method of the nano-crystal fibrin magnetic particle of a kind of Adsorption of Heavy Metal Ions the most according to claim 4, it is characterised in that nano-crystal cellulose dispersion liquid is to be joined in ethylene glycol or glycerol by nano-crystal cellulose.

The preparation method of the nano-crystal fibrin magnetic particle of a kind of Adsorption of Heavy Metal Ions the most according to claim 4, it is characterised in that methanol is 1:1 with the volume ratio of nano-crystal cellulose dispersion liquid, and the rate of addition of nano-crystal cellulose dispersion liquid is 15-20mL/min.

The preparation method of the nano-crystal fibrin magnetic particle of a kind of Adsorption of Heavy Metal Ions the most according to claim 3, it is characterised in that supersound process is 60-80KHz ultrasound wave.

The preparation method of the nano-crystal fibrin magnetic particle of a kind of Adsorption of Heavy Metal Ions the most according to claim 4, it is characterised in that supersound process is 70-90KHz ultrasound wave.

The preparation method of the nano-crystal fibrin magnetic particle of a kind of Adsorption of Heavy Metal Ions the most according to claim 1, it is characterised in that magnetic particle is the iron oxide magnetic particle of 20-50nm.