Deinking agent containing p-nitrobenzyl alcohol and preparation method thereof

Abstract

The invention relates to the technical field of deinking agents, and discloses a deinking agent containing p-nitrobenzyl alcohol and a preparation method thereof.The preparation method comprises the following steps that p-nitrobenzyl alcohol and water are mixed and stirred until the p-nitrobenzyl alcohol is completely dissolved, modified cardanol, modified chitosan and sodium citrate are added and stirred for 1-2 h at the temperature of 40-60 DEG C, then polysiloxane is added, the pH is adjusted to be 8-10, and the deinking agent containing p-nitrobenzyl alcohol is obtained. And filtering to obtain the deinking agent containing p-nitrobenzyl alcohol. The deinking agent disclosed by the invention is high in deinking efficiency and has good biodegradability.

Description

Technical Field

[0001] The invention relates to the technical field of deinking agents, in particular to a deinking agent containing p-nitrobenzyl alcohol and a preparation method thereof. Background Art

[0002] The increasing demand for waste paper has made newsprint, office waste, and magazine paper the primary sources of waste paper for widespread collection and recycling. Improving waste paper reuse rates is a growing concern, and waste paper deinking technology has become a hot research topic in the papermaking industry. Traditional deinking agents primarily rely on surfactants to reduce the surface tension between ink and fiber. While organic solvent-based deinking agents can quickly penetrate ink, they pose safety risks such as excessive volatile organic compounds and flammability. Water-based deinking agents, on the other hand, generally suffer from insufficient solubility for oil-based inks and low deinking efficiency. Therefore, addressing this issue is crucial. For example, patent CN114806261A discloses a deinking agent, its preparation method, and its application. The deinking agent comprises the following components: a solvent, a solubilizing agent, a strongly alkaline substance, and an anti-adhesive agent. This invention not only provides long-lasting deinking performance but also effectively reduces the viscosity of the resulting ink residue. However, its biodegradability is limited, and its deinking efficiency needs to be improved. Summary of the Invention

[0003] (1) Technical problems solved

[0004] In view of the shortcomings of the existing technology, the present invention provides a deinking agent containing p-nitrobenzyl alcohol and a preparation method thereof. The deinking agent of the present invention has high deinking efficiency and good biodegradability.

[0005] (2) Technical solution

[0006] To achieve the above objectives, the present invention provides the following technical solution: a deinking agent containing p-nitrobenzyl alcohol and a preparation method thereof, comprising the following components by weight: 8-12 parts by weight of p-nitrobenzyl alcohol, 5-10 parts by weight of modified cardanol, 4-6 parts by weight of modified chitosan, 1-3 parts by weight of sodium citrate, 0.2-0.4 parts by weight of polysiloxane, and 12-15 parts by weight of water.

[0007] Furthermore, the preparation method of the modified cardanol is:

[0008] Step 1: Add cardanol and 4-vinylbenzoic acid to the reactor, stir and mix, continue to add p-toluenesulfonic acid catalyst and toluene water agent, react at 130-160°C for 4-6 hours, and after the reaction is completed, cool to room temperature, wash and dry to obtain intermediate 1;

[0009] Step 2: Under inert gas protection, add intermediate 1 and hexamethyldisilazane to dichloromethane solvent, stir and mix, then add chloroplatinic acid catalyst dropwise, and continue stirring at 40-50°C for 8-12 hours to react. After the reaction is completed, dry and concentrate under reduced pressure to obtain intermediate 2;

[0010] Step 3: Under the protection of inert gas, add intermediate 2 and benzyl chloride to carbon tetrachloride solvent, stir evenly, react at 30-60°C for 10-12 hours, wash and dry after the reaction, and distill under reduced pressure to obtain modified cardanol.

[0011] Furthermore, the usage ratio of cardanol, 4-vinylbenzoic acid, p-toluenesulfonic acid, and toluene in the step 1 is 6.6-6.8 g: 3.1-3.4 g: 0.22-0.25 g: 18-20 mL.

[0012] Furthermore, the usage ratio of dichloromethane, intermediate 1, hexamethyldisilazane (amine), and chloroplatinic acid in the step 2 is 12-15 mL: 4.5-4.8 g: 1.7-2 g: 0.05-0.06 g.

[0013] Furthermore, the usage ratio of carbon tetrachloride, intermediate 2, and benzyl chloride in step 3 is 40-42 mL: 8.6-8.8 g: 4.5-4.7 g.

[0014] Furthermore, the preparation method of the modified chitosan is:

[0015] S1: Add palmitic acid and epichlorohydrin to toluene solvent, stir and mix, then add potassium hydroxide catalyst, stir at 60-80°C for 7-10 hours. After the reaction is complete, distill under reduced pressure and dry to obtain intermediate 1;

[0016] S2: Under inert gas protection, chitosan is swelled in a 3% by mass acetic acid solution for 1-2 hours, and then intermediate 1 is added thereto, stirred and mixed, and reacted at 80-90°C for 12-14 hours. After the reaction is completed, the mixture is cooled, the pH is adjusted to 7.0, precipitated, washed and dried to obtain modified chitosan.

[0017] Furthermore, the usage ratio of toluene, palmitic acid, epichlorohydrin and potassium hydroxide in S1 is 25-27 mL: 2.56-2.58 g: 3.23-3.25 g: 0.02-0.03 g.

[0018] Furthermore, the usage ratio of chitosan, acetic acid and intermediate 1 in S2 is 3-3.2 g:18-20 mL:1.4-1.6 g.

[0019] Furthermore, the deinking agent containing p-nitrobenzyl alcohol and its preparation method are as follows: p-nitrobenzyl alcohol is mixed with water, stirred until completely dissolved, modified cardanol, modified chitosan, and sodium citrate are added, stirred at 40-60°C for 1-2 hours, and then polysiloxane is added, the pH is adjusted to 8-10, and the deinking agent containing p-nitrobenzyl alcohol is obtained after filtering.

[0020] (3) Beneficial technical effects

[0021] The invention comprises the following steps: mixing p-nitrobenzyl alcohol with water, stirring until completely dissolved, adding modified cardanol, modified chitosan and sodium citrate, stirring at 40-60 DEG C for 1-2 hours, adding polysiloxane, adjusting the pH to 8-10, and filtering to obtain a deinking agent containing p-nitrobenzyl alcohol.

[0022] The surfactant used as the raw material for preparing the deinking agent has good emulsification, penetration, dispersion ability and good biodegradability due to its unique structure, and has excellent environmental performance. In the process of preparing modified cardanol, a quaternary ammonium salt group is introduced. The cation of the quaternary ammonium salt (-N + ) can strongly adsorb negatively charged ink particles through electrostatic action, neutralize surface charge, weaken the binding force between ink and fiber, make ink more easily detached from the fiber surface, and improve deinking efficiency. Chitosan plays multiple key roles in deinking agents through its unique cationic, adsorbent, film-forming and biodegradable properties, which can significantly improve deinking efficiency and fiber quality. The alkylated modified chitosan can strongly adsorb non-polar components in the ink through van der Waals forces due to the long carbon chain introduced by alkylation. The hydrophobic alkyl chains and hydrophilic chitosan skeleton of the alkylated chitosan spontaneously assemble into micelles, which wrap the ink particles, reduce the oil-water interfacial tension, improve the emulsion stability, and thus improve the deinking efficiency of the deinking agent. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the H NMR spectrum of the intermediate 1 in Example 1(1).

[0024] Figure 2 This is the H NMR spectrum of the intermediate 2 in Example 1(2).

[0025] Figure 3 This is the H-NMR spectrum of the modified cardanol in Example 1(3).

[0026] Figure 4 This is the H NMR spectrum of the intermediate 1 in Example 1(4).

[0027] Figure 5 This is the H-NMR spectrum of the modified chitosan in Example 1(5). DETAILED DESCRIPTION

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0029] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] Example 1

[0031] (1) Add 6.6 g of cardanol and 3.1 g of 4-vinylbenzoic acid to the reactor, stir and mix, continue to add 0.22 g of p-toluenesulfonic acid catalyst and 18 mL of toluene water agent, react at 130 ° C for 4 h, and after the reaction is completed, cool to room temperature, wash and dry to obtain intermediate 1; the reaction process is as follows:

[0032]

[0033] (2) Under nitrogen protection, 4.5 g of intermediate 1 and 1.7 g of hexamethyldisilazane were added to 12 mL of dichloromethane solvent and stirred to mix. Then, 0.05 g of chloroplatinic acid catalyst was added dropwise and stirred at 40 ° C for 8 h to react. After the reaction was completed, the mixture was dried and concentrated under reduced pressure to obtain intermediate 2. The reaction process is as follows:

[0034]

[0035] (3) Under nitrogen protection, 8.6 g of intermediate 2 and 4.5 g of benzyl chloride were added to 40 mL of carbon tetrachloride solvent, stirred evenly, and reacted at 30° C. for 10 h. After the reaction was completed, the mixture was washed and dried, and distilled under reduced pressure to obtain modified cardanol. The reaction process is as follows:

[0036]

[0037] (4) Add 2.56 g of palmitic acid and 3.23 g of epichlorohydrin to 25 mL of toluene solvent, stir and mix, then add 0.02 g of potassium hydroxide catalyst, stir at 60°C for 7 h. After the reaction is completed, distill under reduced pressure and dry to obtain intermediate 1. The reaction process is as follows:

[0038]

[0039] (5) Under nitrogen protection, 3 g of chitosan was swollen in 18 mL of 3% acetic acid solution for 1 h. Then, 1.4 g of intermediate 1 was added thereto, stirred and mixed, and reacted at 80°C for 12 h. After the reaction, the mixture was cooled, the pH was adjusted to 7.0, precipitated, washed, and dried to obtain modified chitosan. The reaction process is as follows:

[0040]

[0041] (6) 8 parts by weight of p-nitrobenzyl alcohol was mixed with 12 parts by weight of water and stirred until completely dissolved. 5 parts by weight of modified cardanol, 4 parts by weight of modified chitosan, and 1 part by weight of sodium citrate were added and stirred at 40° C. for 1 h. 0.2 parts by weight of polysiloxane was then added and the pH was adjusted to 8. After filtering, a deinking agent containing p-nitrobenzyl alcohol was obtained.

[0042] Example 2

[0043] (1) Add 6.8 g of cardanol and 3.4 g of 4-vinylbenzoic acid to a reactor, stir and mix, continue to add 0.25 g of p-toluenesulfonic acid catalyst and 20 mL of toluene water agent, react at 160 ° C for 6 h, and after the reaction is completed, cool to room temperature, wash and dry to obtain intermediate 1;

[0044] (2) Under nitrogen protection, 4.8 g of intermediate 1 and 2 g of hexamethyldisilazane were added to 15 mL of dichloromethane solvent, stirred and mixed, and then 0.06 g of chloroplatinic acid catalyst was added dropwise. The mixture was stirred at 50°C for 12 h to react. After the reaction was completed, the mixture was dried and concentrated under reduced pressure to obtain intermediate 2;

[0045] (3) Under nitrogen protection, 8.8 g of intermediate 2 and 4.7 g of benzyl chloride were added to 42 mL of carbon tetrachloride solvent, stirred evenly, and reacted at 60° C. for 12 h. After the reaction was completed, the mixture was washed and dried, and distilled under reduced pressure to obtain modified cardanol;

[0046] (4) Add 2.58 g of palmitic acid and 3.25 g of epichlorohydrin to 27 mL of toluene solvent, stir and mix, then add 0.03 g of potassium hydroxide catalyst, stir at 80°C for 10 h. After the reaction is complete, distill under reduced pressure and dry to obtain intermediate 1;

[0047] (5) Under nitrogen protection, 3.2 g of chitosan was swollen in 20 mL of 3% acetic acid solution for 2 h, and then 1.6 g of intermediate 1 was added thereto, stirred and mixed, and reacted at 90°C for 14 h. After the reaction was completed, the mixture was cooled, the pH was adjusted to 7.0, and the mixture was precipitated, washed, and dried to obtain modified chitosan.

[0048] (6) 12 parts by weight of p-nitrobenzyl alcohol was mixed with 15 parts by weight of water and stirred until completely dissolved. 10 parts by weight of modified cardanol, 6 parts by weight of modified chitosan, and 3 parts by weight of sodium citrate were added, and the mixture was stirred at 60° C. for 2 h. Then, 0.4 parts by weight of polysiloxane was added, the pH was adjusted to 10, and the mixture was filtered to obtain a deinking agent containing p-nitrobenzyl alcohol.

[0049] Example 3

[0050] (1) Add 6.7 g of cardanol and 3.3 g of 4-vinylbenzoic acid to a reactor, stir and mix, continue to add 0.24 g of p-toluenesulfonic acid catalyst and 19 mL of toluene water agent, react at 145 ° C for 5 h, and after the reaction is completed, cool to room temperature, wash and dry to obtain intermediate 1;

[0051] (2) Under nitrogen protection, 4.6 g of intermediate 1 and 1.8 g of hexamethyldisilazane were added to 13 mL of dichloromethane solvent, stirred and mixed, and then 0.05 g of chloroplatinic acid catalyst was added dropwise. The mixture was stirred at 45 ° C for 10 h to react. After the reaction was completed, the mixture was dried and concentrated under reduced pressure to obtain intermediate 2;

[0052] (3) Under nitrogen protection, 8.7 g of intermediate 2 and 4.6 g of benzyl chloride were added to 41 mL of carbon tetrachloride solvent, stirred evenly, and reacted at 45° C. for 11 h. After the reaction was completed, the mixture was washed and dried, and distilled under reduced pressure to obtain modified cardanol;

[0053] (4) Add 2.57 g of palmitic acid and 3.24 g of epichlorohydrin to 26 mL of toluene solvent, stir and mix, then add 0.02 g of potassium hydroxide catalyst, stir at 70°C for 8 h. After the reaction is complete, distill under reduced pressure and dry to obtain intermediate 1;

[0054] (5) Under nitrogen protection, 3.1 g of chitosan was swollen in 19 mL of 3% acetic acid solution for 1 h, and then 1.5 g of intermediate 1 was added thereto, stirred and mixed, and reacted at 85°C for 13 h. After the reaction was completed, the mixture was cooled, the pH was adjusted to 7.0, and the mixture was precipitated, washed, and dried to obtain modified chitosan.

[0055] (6) 10 parts by weight of p-nitrobenzyl alcohol was mixed with 13 parts by weight of water and stirred until completely dissolved. 7 parts by weight of modified cardanol, 5 parts by weight of modified chitosan, and 2 parts by weight of sodium citrate were added and stirred at 50° C. for 1 h. 0.3 parts by weight of polysiloxane was then added and the pH was adjusted to 9. After filtering, a deinking agent containing p-nitrobenzyl alcohol was obtained.

[0056] Example 4

[0057] (1) Add 6.6 g of cardanol and 3.2 g of 4-vinylbenzoic acid to a reactor, stir and mix, continue to add 0.23 g of p-toluenesulfonic acid catalyst and 18 mL of toluene water agent, react at 140 ° C for 4 h, and after the reaction is completed, cool to room temperature, wash and dry to obtain intermediate 1;

[0058] (2) Under nitrogen protection, 4.6 g of intermediate 1 and 1.8 g of hexamethyldisilazane were added to 13 mL of dichloromethane solvent and stirred to mix. Then, 0.05 g of chloroplatinic acid catalyst was added dropwise and stirred at 43 ° C for 9 h. After the reaction, the mixture was dried and concentrated under reduced pressure to obtain intermediate 2;

[0059] (3) Under nitrogen protection, 8.7 g of intermediate 2 and 4.5 g of benzyl chloride were added to 40 mL of carbon tetrachloride solvent, stirred evenly, and reacted at 40° C. for 10 h. After the reaction was completed, the mixture was washed and dried, and distilled under reduced pressure to obtain modified cardanol;

[0060] (4) Add 2.56 g of palmitic acid and 3.24 g of epichlorohydrin to 25 mL of toluene solvent, stir and mix, then add 0.02 g of potassium hydroxide catalyst, stir at 65°C for 8 h. After the reaction is complete, distill under reduced pressure and dry to obtain intermediate 1;

[0061] (5) Under nitrogen protection, 3 g of chitosan was swollen in 18 mL of 3% acetic acid solution for 1 h, and then 1.5 g of intermediate 1 was added thereto, stirred and mixed, and reacted at 85°C for 12 h. After the reaction was completed, the mixture was cooled, the pH was adjusted to 7.0, and the mixture was precipitated, washed, and dried to obtain modified chitosan.

[0062] (6) 9 parts by weight of p-nitrobenzyl alcohol was mixed with 13 parts by weight of water and stirred until completely dissolved. 6 parts by weight of modified cardanol, 5 parts by weight of modified chitosan, and 1 part by weight of sodium citrate were added and stirred at 45° C. for 1 h. 0.2 parts by weight of polysiloxane was then added and the pH was adjusted to 8. After filtering, a deinking agent containing p-nitrobenzyl alcohol was obtained.

[0063] Example 5

[0064] (1) Add 6.8 g of cardanol and 3.3 g of 4-vinylbenzoic acid to a reactor, stir and mix, continue to add 0.24 g of p-toluenesulfonic acid catalyst and 20 mL of toluene water agent, react at 150 ° C for 6 h, and after the reaction is completed, cool to room temperature, wash and dry to obtain intermediate 1;

[0065] (2) Under nitrogen protection, 4.7 g of intermediate 1 and 1.9 g of hexamethyldisilazane were added to 14 mL of dichloromethane solvent, stirred and mixed, and then 0.06 g of chloroplatinic acid catalyst was added dropwise. The mixture was stirred at 50°C for 11 h to react. After the reaction was completed, the mixture was dried and concentrated under reduced pressure to obtain intermediate 2;

[0066] (3) Under nitrogen protection, 8.7 g of intermediate 2 and 4.7 g of benzyl chloride were added to 42 mL of carbon tetrachloride solvent, stirred evenly, and reacted at 50° C. for 12 h. After the reaction was completed, the mixture was washed and dried, and distilled under reduced pressure to obtain modified cardanol;

[0067] (4) Add 2.58 g of palmitic acid and 3.24 g of epichlorohydrin to 27 mL of toluene solvent, stir and mix, then add 0.03 g of potassium hydroxide catalyst, stir at 75°C for 9 h. After the reaction is complete, distill under reduced pressure and dry to obtain intermediate 1;

[0068] (5) Under nitrogen protection, 3.2 g of chitosan was swollen in 20 mL of 3% acetic acid solution for 2 h, and then 1.5 g of intermediate 1 was added thereto, stirred and mixed, and reacted at 90°C for 13 h. After the reaction was completed, the mixture was cooled, the pH was adjusted to 7.0, and the mixture was precipitated, washed, and dried to obtain modified chitosan;

[0069] (6) 11 parts by weight of p-nitrobenzyl alcohol was mixed with 14 parts by weight of water and stirred until completely dissolved. 9 parts by weight of modified cardanol, 6 parts by weight of modified chitosan, and 3 parts by weight of sodium citrate were added and stirred at 55° C. for 2 h. 0.4 parts by weight of polysiloxane was then added and the pH was adjusted to 10. After filtering, a deinking agent containing p-nitrobenzyl alcohol was obtained.

[0070] Comparative Example 1

[0071] This comparative example is different from Example 5 in that the intermediate 1 in (1) is used instead of modified cardanol.

[0072] Comparative Example 2

[0073] Compared with Example 5, this comparative example is different in that the intermediate 2 in (2) is used instead of modified cardanol.

[0074] Comparative Example 3

[0075] Compared with Example 5, this comparative example differs in that chitosan is used instead of modified chitosan.

[0076] Deinking efficiency test:

[0077] The deinking efficiency of the deinking agents containing p-nitrobenzyl alcohol prepared in Examples 1-5 and Comparative Examples 1-3 was tested according to GB / T 24993-2010 “Determination of the degree of deinking of paper and paperboard”. The results are shown in Table 1.

[0078] Biodegradation performance test:

[0079] The deinking agents containing p-nitrobenzyl alcohol prepared in Examples 1-5 and Comparative Examples 1-3 were subjected to biodegradation performance tests according to GB / T 15818-2006 “Test Method for Biodegradation of Surfactants”. The results are shown in Table 1.

[0080] Table 1: Deinking rate and degradation rate tests.

[0081] Group Whiteness (%) Deinking time (min) Deinking rate (%) Degradation rate (%) Example 1 87.7 7 90.8 96.5 Example 2 88.8 6 92.3 97.4 Example 3 88.4 6 91.9 97.1 Example 4 87.9 7 91.2 96.8 Example 5 88.5 6 92.0 97.2 Comparative Example 1 84.3 10 87.7 95.3 Comparative Example 2 84.6 10 88.5 95.7 Comparative Example 3 85.9 9 89.7 94.2

[0082] As can be seen from Table 1, the deinking agents containing p-nitrobenzyl alcohol prepared in Examples 1-5 of the present invention have shorter demolding times, and improved deinking rates and degradation rates than the deinking agents prepared in Comparative Examples 1-3, indicating that the deinking agents of the present invention have high deinking efficiency and good biodegradability.

[0083] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0084] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

[0085] Those skilled in the art will appreciate that the foregoing descriptions are merely specific embodiments of the present invention, and not exhaustive. It should be noted that numerous variations and modifications are possible for those skilled in the art, and all such variations and modifications that do not exceed the scope of the claims should be considered within the scope of protection of the present invention.

Claims

1. A deinking agent containing p-nitrobenzyl alcohol, characterized in that: The invention comprises the following components by weight: 8-12 parts by weight of p-nitrobenzyl alcohol, 5-10 parts by weight of modified cardanol, 4-6 parts by weight of modified chitosan, 1-3 parts by weight of sodium citrate, 0.2-0.4 parts by weight of polysiloxane, and 12-15 parts by weight of water.

2. The deinking agent containing p-nitrobenzyl alcohol according to claim 1, characterized in that The preparation method of the modified cardanol is: Step 1: Add cardanol and 4-vinylbenzoic acid to the reactor, stir and mix, continue to add p-toluenesulfonic acid catalyst and toluene water agent, react at 130-160°C for 4-6 hours, and after the reaction is completed, cool to room temperature, wash and dry to obtain intermediate 1; Step 2: Under inert gas protection, add intermediate 1 and hexamethyldisilazane to dichloromethane solvent, stir and mix, then add chloroplatinic acid catalyst dropwise, and continue stirring at 40-50°C for 8-12 hours to react. After the reaction is completed, dry and concentrate under reduced pressure to obtain intermediate 2; Step 3: Under the protection of inert gas, add intermediate 2 and benzyl chloride to carbon tetrachloride solvent, stir evenly, react at 30-60°C for 10-12 hours, wash and dry after the reaction, and distill under reduced pressure to obtain modified cardanol.

3. The deinking agent containing p-nitrobenzyl alcohol according to claim 2, characterized in that The usage ratio of cardanol, 4-vinylbenzoic acid, p-toluenesulfonic acid, and toluene in the step 1 is 6.6-6.8 g: 3.1-3.4 g: 0.22-0.25 g: 18-20 mL.

4. The deinking agent containing p-nitrobenzyl alcohol according to claim 2, characterized in that The usage ratio of dichloromethane, intermediate 1, hexamethyldisilazane, and chloroplatinic acid in the step 2 is 12-15 mL: 4.5-4.8 g: 1.7-2 g: 0.05-0.06 g.

5. The deinking agent containing p-nitrobenzyl alcohol according to claim 2, characterized in that The usage ratio of carbon tetrachloride, intermediate 2, and benzyl chloride in step 3 is 40-42 mL: 8.6-8.8 g: 4.5-4.7 g.

6. The deinking agent containing p-nitrobenzyl alcohol according to claim 1, characterized in that The preparation method of the modified chitosan is: S1: Add palmitic acid and epichlorohydrin to toluene solvent, stir and mix, then add potassium hydroxide catalyst, stir at 60-80°C for 7-10 hours. After the reaction is complete, distill under reduced pressure and dry to obtain intermediate 1; S2: Under inert gas protection, chitosan is swelled in a 3% by mass acetic acid solution for 1-2 hours, and then intermediate 1 is added thereto, stirred and mixed, and reacted at 80-90°C for 12-14 hours. After the reaction is completed, the mixture is cooled, the pH is adjusted to 7.0, precipitated, washed and dried to obtain modified chitosan.

7. The deinking agent containing p-nitrobenzyl alcohol according to claim 6, characterized in that The usage ratio of toluene, palmitic acid, epichlorohydrin and potassium hydroxide in S1 is 25-27 mL: 2.56-2.58 g: 3.23-3.25 g: 0.02-0.03 g.

8. The deinking agent containing p-nitrobenzyl alcohol according to claim 6, characterized in that The usage ratio of chitosan, acetic acid and intermediate 1 in S2 is 3-3.2 g:18-20 mL:1.4-1.6 g.

9. A deinking agent containing p-nitrobenzyl alcohol and a preparation method thereof according to claims 1-8, characterized in that: The deinking agent containing p-nitrobenzyl alcohol and the preparation method thereof are as follows: p-nitrobenzyl alcohol is mixed with water, stirred until completely dissolved, modified cardanol, modified chitosan, and sodium citrate are added, stirred at 40-60° C. for 1-2 hours, and then polysiloxane is added, the pH is adjusted to 8-10, and the deinking agent containing p-nitrobenzyl alcohol is obtained after filtering.

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