CN105597681B - A kind of preparation method for the NCC/PVA/PVP carbon blended sponges that can efficiently remove Heavy Metals in Waters ion and organic dyestuff - Google Patents

Abstract

The invention provides a method for preparing an NCC/PVA/PVP blended carbon sponge capable of efficiently removing heavy metal ions and organic dyes in water by a microwave annealing method, comprising steps: 1) preparing nanofibers from microcrystalline cellulose by a sulfuric acid method plain suspension; 2) polyvinyl alcohol is added to the suspension obtained in step 1); 3) polyvinylpyrrolidone is added to the suspension obtained in step 1); 4) steps 2) and 3) are obtained in The suspensions are mixed in proportion, and then annealed under microwave to obtain nanocellulose/polyvinyl alcohol/polyvinylpyrrolidone blended carbon sponge. The blended carbon sponge prepared by the preparation method of the present invention has a stable shape, high product purity, and high removal rate of heavy metal ions and organic solvents.

Description

A kind of NCC/PVA/ Preparation method of PVP blended carbon sponge

technical field

The present invention relates to a preparation method of nano-cellulose/polyvinyl alcohol/polyvinylpyrrolidone (NCC/PVA/PVP) blended carbon sponge, in particular to a microwave annealing method to prepare NCC for efficiently removing heavy metal ions and organic dyes in water Preparation method of /PVA/PVP blended carbon sponge.

Background technique

Porous carbon materials with a network structure composed of interpenetrating or closed pores not only have the advantages of carbon material properties (such as high chemical stability, good electrical conductivity, low price, etc.), but also have the characteristics of large specific surface area. Therefore, porous carbon materials can be used in the fields of separation and purification, catalysis, optical devices, energy storage, bioseparation membranes, and nanoreactors. The macroporous structure formed by the three-dimensional network structure makes the porous carbon material have excellent adsorption performance. At present, with the deepening of research on porous carbon materials, the preparation of porous carbon materials not only needs to control its mesoscopic structure, pore size and pore arrangement, but also requires its micron-scale macroscopic morphology. Mesoporous carbon materials with various shapes such as spheres, fibers, rods, single crystals and bulk materials have been successfully synthesized. This makes porous carbon materials play an important role in the fields of sewage treatment and water purification.

Polymer-based nanocomposites refer to materials with excellent performance obtained by compounding polymers with metals, inorganic non-metals, and organic nanoparticles. This kind of composite material not only has the advantages of polymer itself, but also has the specific properties of nanoparticles, so it can be applied in the fields of mechanics, catalysis, functional materials (light, electricity, magnetism, sensitivity), etc., and even new Its properties and functions, such as high strength, high modulus, high toughness, high heat resistance, high transparency, high conductivity, high barrier to oil and gas, etc., thus have broad development prospects. Polymer nanocomposites can be divided into polymer/inorganic nanocomposites and polymer/polymer nanocomposites. In recent years, a large number of studies have focused on the preparation of carbon fibers with different shapes and structures of single components, carbon aerogels, etc. to remove heavy metal ions and organic dyes in water. For multi-component blending, nanomaterials and polymers There are few studies on hybrid carbon materials. The currently prepared adsorption materials for heavy metal ions and organic dyes include porous fibers, graphene aerogels, carbon nanocomposite fibers, and starch-carbon membrane materials. For example, based on polystyrene as the matrix proposed by Zhao et al., the fiber with multi-void structure was prepared by electrospinning technology, which has a high adsorption rate for oil (Jing Wu, Nu Wang, Li Wang, Hua Dong, Yong Zhao, and LeiJing ACS Appl.Mater.Interfaces,2012,4,3207-3212); the compressible graphene airgel prepared by self-assembly method proposed by Li et al. can be recycled for the removal of organic solvents (Jihao Li, Jingye Li ,Hu Meng,Siyuan Xie,Bowu Zhang,Linfan Li,Hongjuan Ma,Jianyong Zhang and Ming Yu,J.Mater.Chem.A,2014,2,2934–2941; Cotton fiber as raw material proposed by Guo et al. Porous carbon nanocomposite fibers that can magnetically adsorb heavy metal ions prepared by annealing and calcination (Jiahua Zhu, HongboGu, Jiang Guo, Minjiao Chen, Huige Wei, Zhiping Luo, Henry A.Colorado, Narendranath Yerra, Daowei Ding, Thomas C .Ho, Neel Haldolaarachchige, Jack Hopper, DavidP.Young, Zhanhu Guo and Suying Wei, J.Mater.Chem.A, 2014, 2, 2256–2265); proposed by Mezzenga et al. Membranes for water purification can remove heavy metal ions and organic solvents (Sreenath Bolisetty and Raffaele Mezzenga, Nature Nanotechnology, 2016, DOI: 10.1038/NNANO.2015.310.

In recent years, microwave has been widely used in the field of chemistry, including preparation of molecular sieves, synthesis of radiopharmaceuticals, synthesis and intercalation reactions of inorganic complexes, organic reactions under dry conditions, plasma chemistry, sample pretreatment and catalysis in analytical chemistry. Wait. In recent years, the microwave method has attracted great attention in the material science community because of its special effects. Compared with the traditional method, the microwave method has the advantages of fast reaction speed, mild reaction conditions and high reaction efficiency, and the product has higher purity, narrow particle size distribution and uniform shape, and is suitable for large-scale industrial production Therefore, it shows a good development trend and broad application prospects in the field of nanomaterial synthesis. Porous carbon nanocomposite fibers that can magnetically absorb heavy metal ions were prepared from cotton fibers by microwave annealing method proposed by Guo et al. (JiahuaZhu, Hongbo Gu, Jiang Guo, Minjiao Chen, Huige Wei, Zhiping Luo, Henry A. Colorado, Narendranath Yerra, Daowei Ding, Thomas C.Ho, Neel Haldolaarachchige, JackHopper, David P.Young, Zhanhu Guo and Suying Wei, J.Mater.Chem.A, 2014, 2, 2256–2265); but regarding NCC/ There are few reports on PVA/PVP blended carbon sponges. Research and invention in this area is of great significance for the treatment of water pollution and large-scale production.

Contents of the invention

Aiming at the existing problems of excessive heavy metal ions and organic dyes in water bodies and existing technologies, an object of the present invention is to provide a NCC/PVA/PVP co-polymer that can efficiently remove heavy metal ions and organic dyes in water bodies by microwave annealing. Preparation method of carbon-mixed sponge.

According to the preparation method of the NCC/PVA/PVP blended carbon sponge for efficiently removing heavy metal ions and organic dyes in water by microwave annealing method of the present invention, the method comprises the following steps:

1) Microcrystalline cellulose (MCC) is treated with sulfuric acid with a mass percentage concentration of 40-70% at a reaction temperature of 35-80°C for 10-80min to prepare nanocellulose (NCC), wherein the microcrystalline fiber The mass percentage of the element and the sulfuric acid is 1:5-20, and then the prepared nanocellulose is dispersed in water, and prepared into a uniform suspension under ultrasonic conditions, and the obtained suspension is first mechanically stirred for 1-3 hours, Then further disperse in an ultrasonic cell pulverizer for 30 minutes, the intensity of the ultrasonic wave is 500-1200W, wherein 100-500 parts by weight of deionized water is dispersed with respect to 1 part by weight of the prepared nanocellulose, thereby making Suspension with a mass percentage of 0.2-1%;

2) Add polyvinyl alcohol (PVA) particles to the homogeneous suspension obtained in step 1), so that the mass percentage concentration of polyvinyl alcohol in the suspension is 5-20%, and then continue to disperse under the ultrasonic cell pulverizer for 2 Hours, prepared into a suspension A;

3) Add polyvinylpyrrolidone (PVP) powder to the homogeneous suspension obtained in step 1), so that the mass percentage concentration of polyvinylpyrrolidone in the suspension is 5-40%, under a magnetic stirrer or an ultrasonic cell pulverizer Continue to disperse for 2 hours, and prepare suspension B;

4) Mix the suspensions A and B obtained in steps 2) and 3) according to the volume ratio of 5:1 to 1:1 to obtain a precursor solution, and add a mass concentration of 1% of the volume of the precursor solution to The NCC/PVA/PVP blended carbon sponge can be obtained by annealing 10% sulfuric acid under microwave, wherein the microwave annealing is to react under 600W microwave for 5 minutes, and then adjust the microwave to 900W to continue the reaction for 10 minutes.

Preferably, the mass percent concentration of sulfuric acid described in step 1) is 50-60%, more preferably 58-60%, even more preferably 58%; the reaction temperature is 40-60°C, more preferably 50-60°C , more preferably 50°C; the reaction time is 30-50min, more preferably 35-40min, even more preferably 35min; the mass percentage of MCC and sulfuric acid is 1:8-15, more preferably 1:10-15, More preferably, it is 1:10.

Preferably, relative to 1 part by weight of the prepared nanocellulose in step 1), it is preferably dispersed with 150-300 parts by weight, more preferably 200-250 parts by weight, and even more preferably 200 parts by weight of deionized water, Thus, a suspension with a mass percentage of 0.33-0.66%, more preferably 0.4-0.5%, and even more preferably 0.5% is prepared.

Preferably, the intensity of the ultrasonic waves in the ultrasonic dispersion in step 1) is 700-1000W, more preferably 800-1000W, even more preferably 800W.

Preferably, the PVA particles in step 2) are PVA particles with a weight average molecular weight of 170,000-220,000 and an alcoholysis degree of about 88%, more preferably PVA17-88. Add the PVA particles into the homogeneous suspension obtained in 1), so that the mass percent concentration of polyvinyl alcohol in the suspension is 7-15%, more preferably 8-10%, and even more preferably 8%.

Preferably, the PVP powder described in step 3) is a PVP powder with a weight average molecular weight of 10,000 to 70,000, preferably PVP powder K-30, and the PVP powder is added to the homogeneous suspension obtained in step 1), The mass percent concentration of the polyvinylpyrrolidone in the suspension is 10-25%; more preferably 20-25%, even more preferably 20%.

Preferably, the mixing volume ratio of suspensions A and B obtained in steps 2) and 3) in step 4) is 3:1 to 2:1, more preferably 7-5:3, even more preferably 7:3.

According to the preparation method of the present invention, it comprises the following steps:

1) Take 50mL of sulfuric acid with a concentration of 58% prepared in a round bottom flask, add 5g of MCC and react for 35min at 50°C. After the reaction is completed, transfer the reaction product to a beaker and dilute to 800mL with deionized water. Place for 4 hours, then centrifuge at 3000 rpm for 30 minutes, dialyze for 24 hours, vacuum freeze 1 g of NCC obtained at -50°C for 36 hours, and add 200 mL of deionized water to prepare a suspension under ultrasonic conditions. The solution was mechanically stirred for 2 hours, and then further dispersed in an 800W ultrasonic cell pulverizer for 30 minutes to finally obtain a 0.5% uniform suspension;

2) Add 35g of PVA granules (PVA17-88, molecular weight 170,000-220,000, degree of alcoholysis about 88%) to 300mL of the homogeneous suspension obtained in step 1), and prepare a suspension in the suspension under ultrasonic conditions. The mass percent concentration of vinyl alcohol is 8% PVA suspension;

3) Add 5g of PVP powder (PVP powder K-30, molecular weight 1-70,000) to 20mL of the homogeneous suspension obtained in step 1), and prepare the mass percentage of polyvinylpyrrolidone in the suspension under ultrasonic conditions 20% PVP suspension;

4) Preparation of precursor solution

After mixing and stirring the PVA suspension obtained in step 2) and the PVP suspension obtained in step 3) in a ratio of 7:3 by volume, add 1% of the volume of the mixed solution with a mass percentage concentration of 10%. Sulfuric acid obtains precursor solution;

5) Microwave annealing

React the precursor solution obtained in step 4) under 600W microwave for 5 minutes to react NCC, PVA and PVP in the precursor solution, and then adjust the microwave to 900W to continue the reaction for 10 minutes to anneal and carbonize the precursor to obtain an efficient removal of water NCC/PVA/PVP blended carbon sponge with medium heavy metal ions and organic dyes.

No crosslinking agent is used in the preparation method according to the present invention.

According to another aspect of the present invention, a kind of NCC/PVA/PVP blended carbon sponge capable of efficiently removing heavy metal ions and organic dyes in water is provided, and the blended carbon sponge is prepared by the above-mentioned preparation method according to the present invention, which The adsorption of Cr ⁶⁺ reached above 9.3948mg/g.

Beneficial effect

1. According to the preparation method of NCC/PVA/PVP blended carbon sponge of the present invention, PVA and PVP are all simple and easy-to-get high polymers, and the carbon sponge is environmentally friendly and degradable; the blending of NCC/PVA/PVP is just NCC/PVA/PVP blended carbon sponge that can efficiently remove heavy metal ions and organic dyes in water can be obtained;

2. The NCC/PVA/PVP blended carbon sponge prepared according to the method of the present invention to efficiently remove heavy metal ions and organic dyes in water has a stable shape, and can be recycled after absorbing heavy metal ions and organic dyes in water. Secondary pollution;

3, according to the NCC/PVA/PVP blended carbon sponge Fourier transform infrared spectra that prepares according to the method of the present invention shows that product does not have peak to appear before wave number 1500cm ^-1 , illustrates that NCC/PVA/PVP blended carbon sponge has the carbon of high purity Skeleton, the purity of the product obtained by microwave annealing is very high;

4. The NCC/PVA/PVP blended carbon sponge prepared according to the method of the present invention has a higher removal rate of heavy metal ions and organic solvents;

6. The NCC/PVA/PVP blended carbon sponge prepared by the method of the present invention has a wide range of raw material sources and low price, which reduces the production cost of the product and is conducive to industrialization and popularization.

Description of drawings

Fig. 1 is a flow chart of the preparation process of NCC/PVA/PVP blended carbon sponge according to the present invention.

Fig. 2 is the Fourier transform infrared spectrogram of the NCC/PVA/PVP blended carbon sponge prepared according to Example 1 and the reactants NCC, PVA and PVP.

Fig. 3 is the ultraviolet spectrophotometric spectrum diagram of the NCC/PVA/PVP blended carbon sponge to potassium dichromate adsorption process according to Experimental Example 1.

Fig. 4 is the concentration change before and after adsorption of potassium dichromate by the NCC/PVA/PVP blended carbon sponge according to Experimental Example 1.

Fig. 5 shows the concentration change of the NCC/PVA/PVP blended carbon sponge before and after adsorption of lead ions according to Experimental Example 2.

Fig. 6 shows the concentration change of the NCC/PVA/PVP blended carbon sponge before and after adsorption of mercury ions according to Experimental Example 3.

Fig. 7 is an ultraviolet spectrophotometric spectrum diagram of the methylene blue adsorption process of the NCC/PVA/PVP blended carbon sponge according to Experimental Example 4.

Fig. 8 is the concentration change of the NCC/PVA/PVP blended carbon sponge before and after the adsorption of methylene blue according to Experimental Example 4.

Fig. 9 is a comparison chart of porosity of products obtained according to Examples 1, 2 and 3.

Figure 10 is a comparison chart of the removal rates of heavy metal ions and organic dyes obtained according to Examples 1, 2 and 3.

detailed description

According to the preparation method of the present invention, the NCC prepared from high polymer PVA, PVP and MCC firstly has MCC to prepare NCC with sulfuric acid method, and then disperses NCC into water and prepares a uniform and uniform suspension under the action of ultrasound. Then use NCC suspension as solvent to prepare PVA and PVP solutions respectively, mix PVA solution and PVP solution according to a certain ratio under acidic conditions to form a precursor solution, and react under microwave to form carbon sponge. This process does not require any Complex experimental equipment without adding any cross-linking agent, the internal components form a stable network structure through self-assembly, and then microwave degeneration carbonization forms a high-porosity carbon sponge, green and pollution-free, simple process, convenient operation, and high yield , is an efficient, quick and environmentally friendly preparation method for preparing NCC/PVA/PVP blended carbon sponges that can efficiently remove heavy metal ions and organic dyes in water.

According to the preparation method of the present invention, the PVA particles are PVA particles with a molecular weight of 170,000-220,000 and an alcoholysis degree of about 88%, preferably PVA17-88. When the molecular weight of PVA is too high, the price of PVA is higher, the cost rises, and it is difficult to prepare a suspension because it is easy to solidify; and when the molecular weight of PVA is too low, although the price may be cheap, but because the molecular chain is too short, A three-dimensional network structure with strong adsorption cannot be constructed with PVP and NCC. Therefore, the molecular weight of the PVA particles according to the preparation method of the present invention is preferably 170,000-220,000.

In the preparation method according to the present invention, the PVP powder can be K-30PVP powder, and its weight average molecular weight is about 10,000-70,000, which is more suitable. No pollution.

In the NCC/PVA/PVP blended carbon sponge of heavy metal ions and organic dyes in the efficient removal of water prepared by the preparation method of the present invention, PVA and PVP are all simple and easy to obtain polymers, so the production cost is greatly reduced, and because PVA and PVP itself has a long molecular chain structure, which is beneficial to the construction of the network structure in the carbon sponge, thereby improving the adsorption performance of the carbon sponge.

Hereinafter, the present invention will be described in detail. Before proceeding with the description, it should be understood that the terms used in this specification and appended claims should not be construed as limited to ordinary and dictionary meanings, but should be best interpreted while allowing the inventor to properly define the terms On the basis of the principles of the present invention, explanations are made based on meanings and concepts corresponding to the technical aspects of the present invention. Accordingly, the descriptions set forth herein are preferred examples for illustrative purposes only and are not intended to limit the scope of the invention, so that it should be understood that other, etc. price or improvement.

Example 1

1) Take 50mL of sulfuric acid with a concentration of 58% prepared in a round bottom flask, add 5g of MCC and react for 35min at 50°C. After the reaction is completed, transfer the reaction product to a beaker and dilute to 800mL with deionized water. Place for 4 hours, then centrifuge at 3000 rpm for 30 minutes, dialyze for 24 hours, vacuum freeze 1 g of NCC obtained at -50°C for 36 hours, and add 200 mL of deionized water to prepare a suspension under ultrasonic conditions. The solution was mechanically stirred for 2 hours, and then further dispersed in an 800W ultrasonic cell pulverizer for 30 minutes to finally obtain a 0.5% uniform suspension; according to the literature (Shan Liu, Yan-Jun Liu, Fu Deng, Ming- Guo Ma and Jing Bian, RSCAdv., 2015, 5, 74198-74205).

2) Add 35g of PVA granules (PVA17-88, molecular weight 170,000-220,000, degree of alcoholysis about 88%) to 300mL of the homogeneous suspension obtained in step 1), and prepare a suspension in the suspension under ultrasonic conditions. The mass percent concentration of vinyl alcohol is 8% PVA suspension;

3) Add 5g of PVP powder (PVP powder K-30, molecular weight 1-70,000) to 20mL of the homogeneous suspension obtained in step 1), and prepare the mass percentage of polyvinylpyrrolidone in the suspension under ultrasonic conditions 20% PVP suspension;

4) Preparation of precursor solution

After mixing and stirring the PVA suspension obtained in step 2) and the PVP suspension obtained in step 3) in a ratio of 7:3 by volume, add 1% of the volume of the mixed solution with a mass percentage concentration of 10%. Sulfuric acid obtains precursor solution;

5) Microwave annealing

React the precursor solution under 600W microwave for 5 minutes to make NCC, PVA and PVP in the precursor solution react to make the precursor solution viscous. NCC/PVA/PVP blended carbon sponge for removing heavy metal ions and organic dyes in water.

The structural changes of NCC, PVA, PVP and the NCC/PVA/PVP blended carbon sponge after the reaction were analyzed by Fourier transform infrared spectroscopy, as shown in Figure 2. There is no absorption peak in the 4000-1500cm ^-1 carbon sponge in the Fourier transform infrared spectrum, indicating that after annealing, only the porous carbon skeleton remains in the precursor solution.

Experimental example 1: Adsorption of heavy metal chromium

The adsorption performance of the NCC/PVA/PVP blended carbon sponge prepared in Example 1 on heavy metal ions was studied by using an ultraviolet absorption spectrophotometer. Accurately weigh 500 mg of potassium dichromate with an analytical balance and dissolve it in 500 mL of deionized water to prepare a solution containing hexavalent chromium ions at a concentration of 372 ppm (mg/L) for use. Measure 40mL of potassium dichromate solution in a beaker with a graduated cylinder, add 1g of the carbon sponge prepared in Example 1, transfer to a shaker whose temperature is set at 30°C, and use a UV absorption spectrophotometer (Techcomp UV2310) measurement once. Figure 3 is the UV spectrophotometric spectrum according to the Cr ⁶⁺ adsorption process. The curves in the figure are from top to bottom when not adsorbed (0min), 3min, 6min, 9min, 12min, 15min, 18min, 21min, 24min, 27min, The ultraviolet absorption curves of 30min and 40min adsorption, it can be seen from the results that as time goes on, the absorbance decreases, which means that the dichromate ion in the water gradually decreases, and the absorbance does not change much when adsorbed for 40 minutes. The dichromate ions have been basically removed. Fig. 4 is the NCC/PVA/PVP blended carbon sponge prepared according to embodiment 1 concentration change before and after potassium dichromate adsorption, as shown in Fig. 4, Cr before adsorption Concentration is ^372ppm , after adsorption concentration is 0.012ppm, The removal rate reaches 99.99%, and the content of heavy metal chromium in the water body after adsorption is 0.012ppm, almost reaching the standard of class I drinking water (GB7467-87).

Experimental Example 2: Adsorption of heavy metal lead

The adsorption performance of the NCC/PVA/PVP blended carbon sponge prepared in Example 1 on heavy metal ions was studied by using an ultraviolet absorption spectrophotometer. Accurately weigh 170 mg of lead acetate with an analytical balance and dissolve it in 500 mL of deionized water to prepare a solution containing divalent lead ions at a concentration of 128 ppm (mg/L) for use. Measure 40mL of lead acetate solution in a beaker with a graduated cylinder, add 1g of the carbon sponge prepared in Example 1, transfer to a shaker with a temperature setting of 30°C, and measure it with an ultraviolet absorption spectrophotometer (Techcomp UV2310) every 3min once. Result as shown in Figure 5, before adsorption, Pb ²⁺ concentration is 128ppm, and after adsorption, Pb ²⁺ concentration is 0.015ppm, and removal rate has reached 99.98%. After adsorption, the content of heavy metal lead in water is better than national standard (experimental atomic absorption Spectrophotometry (chelation extraction method) GB7475-87 or dithizone spectrophotometry GB7470-87).

Experimental Example 3: Adsorption of Heavy Metal Mercury

The adsorption performance of the NCC/PVA/PVP blended carbon sponge prepared in Example 1 on heavy metal ions was studied by using an ultraviolet absorption spectrophotometer. Accurately weigh 180 mg of mercuric chloride with an analytical balance and dissolve it in 500 mL of deionized water to prepare a solution containing divalent mercury ions at a concentration of 76 ppm (mg/L) for use. Measure 40mL of mercuric chloride solution in a beaker with a graduated cylinder, add 1g of the carbon sponge prepared in Example 1, transfer to a shaker whose temperature is set at 30°C, and use a UV absorption spectrophotometer (Techcomp UV2310 ) is measured once. The results are shown in Figure 6, the concentration of Hg ²⁺ before adsorption was 76ppm, the concentration after adsorption was 0.3ppm, and the removal rate reached 99.6%.

Experimental Example 4: Adsorption of Organic Dyes

The adsorption performance of the NCC/PVA/PVP blended carbon sponge prepared in Example 1 on organic dyes was studied by means of an ultraviolet absorption spectrophotometer. Use an analytical balance to accurately weigh 6.4 mg of methylene blue and dissolve it in 500 mL of deionized water to prepare a solution containing methylene blue at a concentration of 12.8 ppm (mg/L) for use. Measure 40mL of methylene blue solution in a beaker with a graduated cylinder, add 1g of the carbon sponge prepared in Example 1, transfer to a shaker with a temperature set at 30°C, and measure with a UV absorption spectrophotometer (Techcomp UV2310) every 3min once. Fig. 7 is the ultraviolet spectrophotometric spectrum diagram according to the methylene blue adsorption process, and the curves in the figure are sequentially from top to bottom when not adsorbed (0min), 3min, 6min, 9min, 12min, 15min, 18min, 21min, 24min, 27min, 30min and The UV absorption curve during 40 minutes of adsorption shows that the absorbance decreases with time, which means that the methylene blue in the water gradually decreases, and the absorbance does not change much after 40 minutes of adsorption, indicating that the methylene blue in the water has basically been removed. . Figure 8 is the concentration change of the NCC/PVA/PVP blended carbon sponge prepared according to Example 1 before and after the adsorption of methylene blue, as shown in Figure 8, the concentration before adsorption is 12.8ppm, the concentration after adsorption is 0.02ppm, and the removal rate reaches 99.84 %.

Example 2

1) Take 50mL of sulfuric acid with a concentration of 58% prepared in a round bottom flask, add 5g of MCC and react for 35min at 50°C. After the reaction is completed, transfer the reaction product to a beaker and dilute to 800mL with deionized water. Place for 4 hours, then centrifuge at 3000 rpm for 30 minutes, dialyze for 24 hours, vacuum freeze 1 g of NCC obtained at -50°C for 36 hours, and add 200 mL of deionized water to prepare a suspension under ultrasonic conditions. The solution was mechanically stirred for 2 hours, and then further dispersed in an 800W ultrasonic cell pulverizer for 30 minutes to finally obtain a 0.5% uniform suspension;

2) Add 35g of PVA granules (PVA17-88, molecular weight 170,000-220,000, degree of alcoholysis about 88%) to 300mL of the homogeneous suspension obtained in step 1), and prepare a suspension in the suspension under ultrasonic conditions. The mass percent concentration of vinyl alcohol is 8% PVA suspension;

3) Add 5g of PVP powder (PVP powder K-30, molecular weight 1-70,000) to 20mL of the homogeneous suspension obtained in step 1), and prepare the mass percentage of polyvinylpyrrolidone in the suspension under ultrasonic conditions 20% PVP suspension;

4) Preparation of precursor solution

After mixing and stirring the PVA suspension obtained in step 2) and the PVP suspension obtained in step 3) in a ratio of 7:3 by volume, add 1% of the volume of the mixed solution with a mass percentage concentration of 10%. Sulfuric acid obtains precursor solution;

5) Calcination and carbonization in tube furnace

The precursor solution was carbonized in a tube furnace at 800° C. for 3 h in a nitrogen atmosphere to completely carbonize the precursor solution to obtain powdery black particles.

Example 2 obtained powdery black particles, and the reason for obtaining the powder was that there was no pre-reaction between NCC/PVA/PVP to build an intersecting network structure, so it was not spongy after calcination. Although the obtained powdery particles also have a certain removal effect on heavy metal ions and organic dyes, the removal rate is not as high as that of the carbon sponge in Example 1. According to the porosity calculation, the higher the porosity, the higher the removal rate, and it is not easy to recycle. deal with.

Example 3

1) Take 50mL of sulfuric acid with a concentration of 58% prepared in a round bottom flask, add 5g of MCC and react for 35min at 50°C. After the reaction is completed, transfer the reaction product to a beaker and dilute to 800mL with deionized water. Place for 4 hours, then centrifuge at 3000 rpm for 30 minutes, dialyze for 24 hours, vacuum freeze 1 g of NCC obtained at -50°C for 36 hours, and add 200 mL of deionized water to prepare a suspension under ultrasonic conditions. The solution was mechanically stirred for 2 hours, and then further dispersed in an 800W ultrasonic cell pulverizer for 30 minutes to finally obtain a 0.5% uniform suspension;

2) Add 35g of PVA granules (PVA17-88, molecular weight 170,000-220,000, degree of alcoholysis about 88%) to 300mL of the homogeneous suspension obtained in step 1), and prepare a suspension in the suspension under ultrasonic conditions. The mass percent concentration of vinyl alcohol is 8% PVA suspension;

3) Add 5g of PVP powder (PVP powder K-30, molecular weight 1-70,000) to 20mL of the homogeneous suspension obtained in step 1), and prepare the mass percentage of polyvinylpyrrolidone in the suspension under ultrasonic conditions 20% PVP suspension;

4) Preparation of precursor solution

After mixing and stirring the PVA suspension obtained in step 2) and the PVP suspension obtained in step 3) in a ratio of 7:3 by volume, add 1% of the volume of the mixed solution with a mass percentage concentration of 10%. Sulfuric acid obtains precursor solution;

5) Microwave reaction

React the precursor solution under 600W microwave for 5 minutes to make the NCC/PVA/PVP in the precursor solution react, and the precursor solution becomes viscous;

6) Calcination and carbonization in tube furnace

The viscous liquid obtained in 5) was carbonized in a tube furnace at 800° C. for 3 hours in a nitrogen atmosphere to make it completely carbonized to obtain a carbon sponge.

Although the carbon sponge obtained in embodiment 3 also has a certain removal effect on heavy metal ions and organic dyes, the removal rate is not as high as that of the carbon sponge in embodiment 1, because the carbon sponge particle porosity obtained in embodiment 3 is not as good as that of embodiment 3. 1 The carbon sponge is high, resulting in a lower removal rate, and it is brittle and brittle, and it is not easy to recycle.

Experimental example 5: Nitrogen adsorption and desorption test

The pore diameters of the carbon sponges or particles prepared in Examples 1 to 3 were detected through the BJH pore size distribution calculation model using conventional nitrogen adsorption-desorption curves. Fig. 9 is a comparison chart of porosity of products obtained according to Examples 1, 2 and 3. It can be seen from the figure that the porosity of the carbon sponge prepared according to Example 1 is much higher than that of the products prepared according to Examples 2 and 3, the former is about 3 to 6 times that of the latter, so the preparation according to the present invention The carbon sponge prepared by the method can effectively remove heavy metal ions and organic dyes.

Experimental Example 6: Comparative Experiment of Removal Rate

According to the methods of Experimental Examples 1 to 4, the products obtained according to Examples 2 and 3 were tested for comparison of heavy metal ion and organic dye rates. Figure 10 is a comparison chart of the removal rates of heavy metal ions and organic dyes obtained according to Examples 1, 2 and 3. It can be seen from the figure that the carbon sponge prepared according to the preparation method of Example 1 of the present invention can achieve more than 99% removal rate of heavy metal ions and organic dyes, even 99.99%, which is much higher than that according to Examples 2 and 3. The removal rate of the obtained product.

Above embodiment is only enumerated as the example of embodiment of the present invention, does not constitute any restriction to the present invention, and those skilled in the art can understand that the modification in the scope of not departing from the spirit and design of the present invention all falls into the protection of the present invention. scope.

Claims (22)

1. a preparation method for removing the nano-cellulose/polyvinyl alcohol/polyvinylpyrrolidone blended carbon sponge of heavy metal ions and organic dyes in the water body, comprising the steps: 1) Treating microcrystalline cellulose with sulfuric acid with a mass percentage concentration of 40-70% at a reaction temperature of 35-80°C for 10-80min to prepare nanocellulose, wherein the microcrystalline cellulose and the sulfuric acid The mass percentage is 1: 5-20, and then the prepared nanocellulose is dispersed in water, and prepared into a uniform suspension under ultrasonic conditions, and the obtained suspension is mechanically stirred for 1-3 hours, and then crushed by ultrasonic cells Further disperse in the machine for 30 minutes, the intensity of the ultrasonic wave is 500-1200W, wherein relative to 1 part by weight of the prepared nanocellulose, disperse with 100-500 parts by weight of deionized water, so that the mass percentage of nanocellulose is 0.2-1% suspension; 2) Add polyvinyl alcohol particles to the homogeneous suspension obtained in step 1), so that the mass percentage concentration of polyvinyl alcohol in the suspension is 5-20%, and then continue to disperse for 2 hours under the ultrasonic cell pulverizer to prepare into a suspension A; 3) Add polyvinylpyrrolidone powder to the homogeneous suspension obtained in step 1), so that the mass percentage concentration of polyvinylpyrrolidone in the suspension is 5-40%, and continue to disperse under a magnetic stirrer or an ultrasonic cell pulverizer After 2 hours, prepare suspension B; 4) Mix the suspensions A and B obtained in steps 2) and 3) according to the volume ratio of 5:1 to 1:1 to obtain a precursor solution, and add a mass concentration of 1% of the volume of the precursor solution to 10% sulfuric acid can be annealed under microwave to obtain nanocellulose/polyvinyl alcohol/polyvinylpyrrolidone blended carbon sponge, wherein the microwave annealing is to react under 600W microwave for 5min, and then adjust the microwave to 900W Continue to react for 10 minutes. 2. The preparation method according to claim 1, characterized in that, the mass percent concentration of sulfuric acid in step 1) is 50-60%; the reaction temperature is 40-60°C; the reaction time is 30-50min; The mass percent of cellulose and sulfuric acid is 1: 8-15. 3. The preparation method according to claim 2, characterized in that, the mass percent concentration of sulfuric acid in step 1) is 58-60%; the reaction temperature is 50-60°C; the reaction time is 35-40min; The mass percent of cellulose and sulfuric acid is 1: 10-15. 4. The preparation method according to claim 2, characterized in that, the mass percent concentration of sulfuric acid in step 1) is 58%; the reaction temperature is 50°C; the reaction time is 35min; the mass percentage of microcrystalline cellulose and sulfuric acid The percentage is 1:10. 5. The preparation method according to claim 1, characterized in that, relative to 1 part by weight of the prepared nanocellulose in step 1), 150-300 parts by weight of deionized water is used to disperse, thereby making the mass percent It is 0.33-0.66% suspension. 6. The preparation method according to claim 5, characterized in that, relative to 1 part by weight of the prepared nanocellulose in step 1), 200-250 parts by weight of deionized water is used to disperse, thereby making a mass percentage It is 0.4-0.5% suspension. 7. The preparation method according to claim 5, characterized in that, relative to 1 part by weight of the prepared nanocellulose in step 1), 200 parts by weight of deionized water are used to disperse, thereby making a mass percentage of 0.5 % suspension. 8 . The preparation method according to claim 1 , wherein the intensity of the ultrasonic waves in the ultrasonic dispersion in step 1) is 700-1000W. 9 . The preparation method according to claim 8 , wherein the intensity of the ultrasonic wave in the ultrasonic dispersion in step 1) is 800-1000W. 10 . The preparation method according to claim 8 , wherein the intensity of the ultrasonic waves in the ultrasonic dispersion in step 1) is 800W. 11 . 11. The preparation method according to claim 1, wherein the polyethylene particles in step 2) are polyethylene particles with a weight average molecular weight of 170,000-220,000 and an alcoholysis degree of 88%; the polyethylene particles The particles are added to the homogeneous suspension obtained in 1), so that the mass percent concentration of polyvinyl alcohol in the suspension is 7-15%. 12. The preparation method according to claim 11, characterized in that the polyethylene particles in step 2) are PVA17-88; the polyethylene particles are added to the homogeneous suspension obtained in 1) to make the suspension The mass percent concentration of polyvinyl alcohol in the liquid is 8-10%. 13. The preparation method according to claim 11, characterized in that the mass percent concentration of polyvinyl alcohol in the suspension in step 2) is 8%. 14. The preparation method according to claim 1, characterized in that the polyvinylpyrrolidone powder in step 3) is a polyvinylpyrrolidone powder with a weight average molecular weight of 10,000-70,000, and adding the polyvinylpyrrolidone powder into the step 1) In the obtained homogeneous suspension, the mass percent concentration of polyvinylpyrrolidone in the suspension is 10-25%. 15. The preparation method according to claim 14, characterized in that the polyvinylpyrrolidone powder in step 3) is polyvinylpyrrolidone K-30, and the polyvinylpyrrolidone powder is added to the homogeneous suspension obtained in step 1). In the turbid liquid, the mass percentage concentration of the polyvinylpyrrolidone in the suspension is 20-25%. 16. The preparation method according to claim 14, characterized in that the mass percent concentration of polyvinylpyrrolidone in step 3) is 20%. 17. The preparation method according to claim 1, characterized in that the mixing volume ratio of the suspensions A and B obtained in step 2) and step 3) in step 4) is 3:1 to 2:1. 18. The preparation method according to claim 17, characterized in that the mixing volume ratio of the suspensions A and B obtained in steps 2) and 3) in step 4) is 7-5:3. 19. The preparation method according to claim 17, characterized in that the mixing volume ratio of the suspensions A and B obtained in step 2) and step 3) in step 4) is 7:3. 20. The preparation method according to claim 1, characterized in that, the preparation method comprises the steps of: 1) Take 50mL of the prepared sulfuric acid with a mass percentage concentration of 58% in a round bottom flask, add 5g of microcrystalline cellulose and react at 50°C for 35min, after the reaction is completed, transfer the reaction product to a beaker and dilute with deionized water to 800mL and let it stand for 4h, then centrifuge at 3000rpm for 30min, dialyze for 24h, vacuum freeze 1g of nanocellulose obtained at -50°C for 36h, and add the obtained nanocellulose to 200mL deionized water under ultrasonic conditions to prepare a suspension Turbid liquid, the resulting suspension was mechanically stirred for 2 hours, and then further dispersed for 30 minutes in an 800W ultrasonic cell pulverizer to finally obtain a homogeneous suspension with a mass percent concentration of nanocellulose of 0.5%; 2) Add 35g of polyvinyl alcohol particles PVA17-88 to 300mL of the homogeneous suspension obtained in step 1) and prepare a polyvinyl alcohol suspension with a mass percentage concentration of polyvinyl alcohol in the suspension of 8% under ultrasonic conditions liquid; 3) Add 5g of polyvinylpyrrolidone powder K-30 to 20mL of the homogeneous suspension obtained in step 1), and prepare polyvinylpyrrolidone with a mass percentage concentration of 20% of polyvinylpyrrolidone in the suspension under ultrasonic conditions suspension; 4) Preparation of precursor solution Mix and stir the polyvinyl alcohol suspension obtained in step 2) and the polyvinylpyrrolidone suspension obtained in step 3) in a ratio of 7:3 by volume, and then add a mass percentage concentration of 1% of the volume of the mixed solution Obtain precursor solution for 10% sulfuric acid; 5) Microwave annealing React the precursor solution obtained in step 4) under 600W microwave for 5 minutes to react nanocellulose, polyvinyl alcohol and polyvinyl pyrrolidone in the precursor solution, then adjust the microwave to 900W and continue the reaction for 10 minutes to anneal and carbonize the precursor A nanocellulose/polyvinyl alcohol/polyvinylpyrrolidone blended carbon sponge capable of efficiently removing heavy metal ions and organic dyes in water was obtained. 21. The preparation method according to any one of claims 1 to 20, characterized in that no crosslinking agent is used in the preparation method. 22. A nano-cellulose/polyvinyl alcohol/polyvinylpyrrolidone blended carbon sponge capable of efficiently removing heavy metal ions and organic dyes in water, said blended carbon sponge passing through any one of claims 1 to 21 It is prepared by the preparation method, and its adsorption to Cr ⁶⁺ reaches above 9.3948mg/g.