Zirconium cross-linked chitosan composite material, preparation method and application

Abstract

The invention discloses a zirconium cross-linked chitosan composite material, a preparation method and application. The infrared spectrogram of the provided zirconium cross-linked chitosan composite material has characteristic peaks at the positions of 3705 + / -2 cm <-1 > to 2995 + / -2 cm <-1 >, 2934 + / -2 cm <-1 >, 1575 + / -2 cm <-1 >, 1454 + / -2 cm <-1 > to 1406 + / -2 cm <-1 > and 1035 + / -2 cm <-1 >. The zirconium cross-linked chitosan composite material provided by the invention has good performance of selectively adsorbing fluorine ions and relatively strong acid resistance, can be applied to defluorination, and also has good cycle stability. The preparation method of the zirconium cross-linked chitosan composite material is simple, high in operability, low in equipment requirement and short in production period.

Description

Technical Field

[0001] The present application belongs to the technical field of fluorine chemical industry and relates to a zirconium cross-linked chitosan composite material, a preparation method and an application thereof. Background Art

[0002] As an important part of the country's strategic emerging industries, fluorine chemical industry plays an irreplaceable role in ensuring the supply of key materials. However, with the rapid expansion of the industry, the problem of treating the by-product fluorine-containing hydrochloric acid has become increasingly prominent. For example, the fluorine-containing hydrochloric acid wastewater produced by the thermal cracking process of tetrafluoroethylene has a hydrochloric acid concentration of about 10wt% to 30wt%, and a fluorine concentration ranging from tens to thousands of ppm; the fluorine-containing hydrochloric acid waste liquid produced as a by-product in the preparation of lithium hexafluorophosphate has a hydrochloric acid concentration of about 30% and a HF mass fraction of 4% to 6%. This type of waste liquid not only causes serious corrosion to production equipment, but also poses the risk of fluoride leakage causing environmental pollution and waste of resources. The adsorption method has great potential for deep defluorination, but current adsorption materials have problems such as poor adsorption performance for fluoride ions and poor acid resistance, making it difficult to meet the needs of industrial continuous production. Summary of the Invention

[0003] Aiming at the problems that existing adsorption materials have poor adsorption performance for fluoride ions and poor acid resistance, a zirconium cross-linked chitosan composite material, a preparation method and application are provided.

[0004] In some embodiments, a zirconium cross-linked chitosan composite material is provided, wherein the infrared spectrum of the zirconium cross-linked chitosan composite material is at 3705±2cm -1 ~2995±2cm -1 、2934±2cm -1 、1575±2cm -1 、1454±2cm -1 ~1406±2cm -1 and 1035±2cm -1 There is a characteristic peak.

[0005] In some embodiments, the zirconium-crosslinked chitosan composite material has an X-ray powder diffraction pattern with characteristic diffraction peaks at the following 2θ (°) angles: 6.0±0.2°, 25.8±0.2°, 41.1±0.2°, and 58.1±0.2°.

[0006] In some embodiments, the decomposition temperature of the zirconium-crosslinked chitosan composite material is 487±5K in a thermogravimetric analysis spectrum.

[0007] In some embodiments, the Raman spectrum of the zirconium cross-linked chitosan composite material is at 507±5 cm -1 、791±5cm -1 、1109±5cm-1 and 1594 ± 5 cm -1 and 2353 ± 5 cm -1 have characteristic peaks at these positions.

[0008] In some embodiments, a method for preparing a zirconium-crosslinked chitosan composite material is provided, including the following steps: in the presence of an acidic solvent, zirconium acetate and chitosan are mixed for physical crosslinking, a crosslinking agent is added for chemical crosslinking reaction, and then dried to obtain the zirconium-crosslinked chitosan composite material;

[0009] The infrared spectrum of the zirconium-crosslinked chitosan composite material has characteristic peaks at 3705 ± 2 cm -1 ~2995 ± 2 cm -1 、2934 ± 2 cm -1 、1575 ± 2 cm -1 、1454 ± 2 cm -1 ~1406 ± 2 cm -1 、1035 ± 2 cm -1 have characteristic peaks at these positions.

[0010] In some embodiments, the method for preparing the zirconium-crosslinked chitosan composite material provided satisfies one or more of the following conditions:

[0011] (1) The ratio of the zirconium acetate to the chitosan is (1~3) mL:(1~5) g;

[0012] (2) In the step of adding the crosslinking agent for chemical crosslinking reaction, the final concentration of the crosslinking agent in the reaction system is 0.5% v / v~1.5% v / v.

[0013] In some embodiments, the method for preparing the zirconium-crosslinked chitosan composite material provided satisfies one or more of the following conditions:

[0014] (1) The X-ray powder diffraction pattern of the zirconium-crosslinked chitosan composite material has characteristic diffraction peaks at the following 2θ (°) angles: 6.0 ± 0.2°, 25.8 ± 0.2°, 41.1 ± 0.2° and 58.1 ± 0.2°;

[0015] (2) The decomposition temperature in the thermogravimetric analysis spectrum of the zirconium-crosslinked chitosan composite material is 487 ± 5 K;

[0016] (3) The Raman spectrum of the zirconium-crosslinked chitosan composite material has characteristic peaks at 507 ± 5 cm -1 、791 ± 5 cm -1 、1109 ± 5 cm -1 、1594 ± 5 cm -1 and 2353 ± 5 cm -1 have characteristic peaks at these positions;

[0017] (4)The crosslinking agent includes one or more of glutaraldehyde and epichlorohydrin;

[0018] (5)The volume ratio of the acidic solvent to zirconium acetate is 100:(1 - 3);

[0019] (6)The acidic solvent is an acetic acid aqueous solution, and the acetic acid concentration in the acetic acid aqueous solution is 2 wt% - 5 wt%.

[0020] In some embodiments, the provided zirconium-crosslinked chitosan composite material or the zirconium-crosslinked chitosan composite material prepared by the provided preparation method is applied to defluorination in solution;

[0021] Optionally, the application of the zirconium-crosslinked chitosan composite material in defluorination of fluorinated brine or fluorinated hydrochloric acid;

[0022] Optionally, in the fluorinated hydrochloric acid, the mass concentration of hydrochloric acid is 10% - 30%, and the concentration of fluorine element by mass is 50 ppm - 4000 ppm;

[0023] Optionally, in the fluorinated brine, the salt content is greater than or equal to 15 g / L.

[0024] In some embodiments, a method for defluorination of fluorinated hydrochloric acid or fluorinated brine is provided, including the following steps:

[0025] Contact at least one of fluorinated hydrochloric acid and fluorinated brine with the zirconium-crosslinked chitosan composite material or the zirconium-crosslinked chitosan composite material prepared by the provided preparation method.

[0026] In some embodiments, the provided method for defluorination of fluorinated hydrochloric acid or fluorinated brine satisfies one or more of the following conditions:

[0027] (1)In the fluorinated hydrochloric acid, the mass concentration of hydrochloric acid is 10% - 30%, and the concentration of fluorine element by mass is 100 ppm - 1000 ppm;

[0028] (2)In the fluorinated brine, the salt content is greater than or equal to 15 g / L.

[0029] The aforementioned provided zirconium-crosslinked chitosan composite material has good performance in selectively adsorbing fluoride ions and strong acid resistance, can be applied to defluorination of hydrochloric acid and high-concentration brine, and has good cycle stability. The provided preparation method of the zirconium-crosslinked chitosan composite material can achieve crosslinking at room temperature, requires low energy consumption, has a simple preparation method, strong operability, low equipment requirements, and a short production cycle. Description of the Drawings

[0030] To more clearly illustrate the technical solutions in the embodiments and examples of the present application and to more comprehensively understand the present application and its beneficial effects, the following will briefly introduce the drawings required for the description of the embodiments or examples. Obviously, the drawings in the following description are only some embodiments of the present application. For those skilled in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0031] Figure 1 Figure 4 shows the X-ray powder diffraction pattern (PXRD) of the zirconium cross-linked chitosan defluorinating agent obtained in Example 1. The ordinate "intensity" represents the diffraction intensity, with the unit of counts; the abscissa is the diffraction angle 2θ, with the unit of degree (°).

[0032] Figure 2 Figure 8 shows the thermogravimetric analysis pattern of the zirconium cross-linked chitosan defluorinating agent obtained in Example 1. The ordinate is the mass percentage, with the unit of %, and the abscissa is the temperature, with the unit of Celsius degree (K). Here, "weight" represents the mass.

[0033] Figure 3 Figure 12 shows the infrared spectrum of the zirconium cross-linked chitosan defluorinating agent obtained in Example 1. The ordinate "transmittance" represents the transmittance, with the unit of (%) ; the abscissa "wavenumber" is the wave number, with the unit of cm -1 ).

[0034] Figure 4 Figure 18 shows the Raman spectrum of the zirconium cross-linked chitosan defluorinating agent obtained in Example 1. The ordinate "signal" represents the signal intensity, with the unit of counts, and the abscissa "raman shift" is the wave number, with the unit of cm -1 ).

[0035] Figure 5 Figure 24 shows the zirconium cross-linked chitosan defluorinating agent obtained in Example 2. Detailed implementation manners

[0036] To facilitate the understanding of the present invention, the following will describe the present invention more comprehensively with reference to the relevant drawings. The preferred embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure content of the present invention more thorough and comprehensive.

[0037] It should be noted that when an element is referred to as "fixed to" another element, it can be directly on the other element or there may also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terms used in the description of the present invention herein are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the related listed items.

[0039] Unless otherwise specified or there is a contradiction, the terms or phrases used herein have the following meanings:

[0040] The selection scope of the terms "and / or", "or / and", and "and / or" used in this application includes any one of two or more related listed items, and also includes any and all combinations of the related listed items. The said any and all combinations include combinations of any two related listed items, any more related listed items, or all related listed items. It should be noted that when at least two conjunctions selected from "and / or", "or / and", and "and / or" are used to connect at least three items, it should be understood that in this application, this technical solution undoubtedly includes the technical solution connected by "logical AND", and also undoubtedly includes the technical solution connected by "logical OR". For example, "A and / or B" includes three parallel solutions: A, B, and "the combination of A and B".

[0041] In this application, the terms "a plurality of", "multiple types", "multiple times", "multiple elements", etc., unless otherwise specified, refer to a quantity greater than 2 or equal to 2. For example, "one or more types" means one type or two or more types.

[0042] The "combinations thereof", "any combinations thereof", "any combination manners thereof", etc. used in this application include all suitable combination manners of any two or any two or more of the listed items.

[0043] In this application, the "suitable combination manners", "suitable manners", "any suitable manners", etc. mentioned herein are "suitable" in that they can implement the technical solution of this application, solve the technical problems of this application, and achieve the expected technical effects of this application.

[0044] In this application, "preferred", "better", "more preferable", "it is advisable" are only used to describe embodiments or examples with better effects, and it should be understood that they do not constitute a limitation on the protection scope of this application.

[0045] In this application, "further", "even further", "especially", etc. are used for descriptive purposes and represent differences in content, but should not be construed as a limitation on the protection scope of this application.

[0046] In this application, "optionally", "optional", and "option" mean having or not having, that is, either of the two parallel options of "having" or "not having". If "optional" appears multiple times in a technical solution, without special instructions, and without contradictions or mutual restrictions, each "optional" is independent.

[0047] In the present invention, in relation to "the first aspect", "the second aspect", "the third aspect", "the fourth aspect", etc., the terms "first", "second", "third", "fourth", etc. are only for descriptive purposes and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first", "second", "third", "fourth", etc. only serve the purpose of non-exhaustive enumeration and description, and it should be understood that they do not constitute a closed limitation on quantity.

[0048] In this application, for the technical features described in an open-ended manner, it includes both the closed technical solutions composed of the listed features and the open technical solutions containing the listed features.

[0049] In this application, regarding the numerical interval (i.e., the numerical range), without special instructions, the optional numerical values are considered continuous within the above numerical interval, and include the two numerical endpoints of this numerical range (i.e., the minimum value and the maximum value), as well as each numerical value between these two numerical endpoints. Without special instructions, when the numerical interval only refers to the integers within this numerical interval, it includes the two endpoint integers of this numerical range, as well as each integer between the two endpoints. In this article, it is equivalent to directly listing each integer. For example, when t is an integer selected from 1 to 10, it means that t is any integer selected from the integer group composed of 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10. In addition, when providing multiple range descriptions of features or characteristics, these ranges can be combined. In other words, unless otherwise specified, the ranges disclosed in this article should be understood to include any and all sub-ranges subsumed therein.

[0050] For the temperature parameter in this application, without special limitations, it allows both constant temperature treatment and fluctuations within a certain temperature range. It should be understood that the so-called constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. Fluctuations within ranges such as ±5°C, ±4°C, ±3°C, ±2°C, and ±1°C are allowed.

[0051] In this application, %(w / w) and wt% both represent weight percentages, %(v / v) refers to volume percentages, and %(w / v) refers to mass-volume percentages.

[0052] The "room temperature" in this application generally refers to 5°C to 30°C, and preferably refers to 25 ± 5°C.

[0053] In this application, "high-concentration brine" refers to a salt-containing aqueous solution with a salt concentration of 15 g / L or more.

[0054] Chitosan is derived from chitin, the second most abundant natural biopolymer globally. The amino and hydroxyl functional groups it possesses can easily form complexes with metal ions (such as zirconium). However, there have been no relevant reports on its use in the treatment of fluoride-containing hydrochloric acid wastewater. The provided zirconium-crosslinked chitosan composite material has high selective adsorption performance for fluoride ions and strong acid resistance, enabling the deep treatment of fluoride in hydrochloric acid and high-concentration brine.

[0055] In some embodiments, a zirconium-crosslinked chitosan composite material is provided. The infrared spectrum of the zirconium-crosslinked chitosan composite material has characteristic peaks at 3705 ± 2 cm -1 ~2995 ± 2 cm -1 、2934 ± 2 cm -1 、1575 ± 2 cm -1 、1454 ± 2 cm -1 ~1406 ± 2 cm -1 and 1035 ± 2 cm -1 .

[0056] In some embodiments, the X-ray powder diffraction pattern of the zirconium-crosslinked chitosan composite material has characteristic diffraction peaks at the following 2θ (°) angles: 6.0 ± 0.2°, 25.8 ± 0.2°, 41.1 ± 0.2° and 58.1 ± 0.2°.

[0057] In some embodiments, the decomposition temperature in the thermogravimetric analysis spectrum of the zirconium-crosslinked chitosan composite material is 487 ± 5 K.

[0058] In some embodiments, the Raman spectrum of the zirconium-crosslinked chitosan composite material has characteristic peaks at 507 ± 5 cm -1 、791 ± 5 cm -1 、1109 ± 5 cm -1 、1594 ± 5 cm -1 and 2353 ± 5 cm -1 .

[0059] In some embodiments, a method for preparing a zirconium-crosslinked chitosan composite material is provided, including the following steps: in the presence of an acidic solvent, zirconium acetate and chitosan are mixed for physical crosslinking, and then a crosslinking agent is added for chemical crosslinking reaction, followed by drying to obtain the zirconium-crosslinked chitosan composite material;

[0060] The infrared spectrum of the zirconium-crosslinked chitosan composite material is at 3705 ± 2 cm -1 ~2995 ± 2 cm -1 、2934 ± 2 cm -1, 1575 ± 2 cm -1 , 1454 ± 2 cm -1 ~1406 ± 2 cm -1 , 1035 ± 2 cm -1 There are characteristic peaks at...

[0061] In some embodiments, in the method for preparing the zirconium-crosslinked chitosan composite provided, the ratio of zirconium acetate to chitosan is (1 - 3) mL : (1 - 5) g. For example, 1 mL : 1 g, 1 mL : 2 g, 1 mL : 3 g, 1 mL : 5 g, 2 mL : 1 g, 2 mL : 1 g, 2 mL : 3 g, 2 mL : 5 g, 3 mL : 1 g, 3 mL : 5 g, or a range composed of any two of the aforementioned ratios.

[0062] In some embodiments, in the method for preparing the zirconium-crosslinked chitosan composite provided, in the step of adding a crosslinking agent for chemical crosslinking reaction, the final concentration of the crosslinking agent in the reaction system is 0.5% v / v - 1.5% v / v. For example, 0.5% v / v, 1% v / v, 1.5% v / v, or a range composed of any two of the aforementioned values.

[0063] In some embodiments, in the method for preparing the zirconium-crosslinked chitosan composite provided, the X-ray powder diffraction pattern of the zirconium-crosslinked chitosan composite has characteristic diffraction peaks at the following 2θ (°) angles: 6.0 ± 0.2°, 25.8 ± 0.2°, 41.1 ± 0.2°, and 58.1 ± 0.2°.

[0064] In some embodiments, in the method for preparing the zirconium-crosslinked chitosan composite provided, the decomposition temperature in the thermogravimetric analysis spectrum of the zirconium-crosslinked chitosan composite is 487 ± 5 K.

[0065] In some embodiments, in the method for preparing the zirconium-crosslinked chitosan composite provided, the Raman spectrum of the zirconium-crosslinked chitosan composite is at 507 ± 5 cm -1 , 791 ± 5 cm -1 , 1109 ± 5 cm -1 , 1594 ± 5 cm -1 and 2353 ± 5 cm -1 There are characteristic peaks at...

[0066] In some embodiments, in the method for preparing the zirconium-crosslinked chitosan composite provided, the crosslinking agent includes one or more of glutaraldehyde and epichlorohydrin.

[0067] In some embodiments, in the provided method for preparing a zirconium-crosslinked chitosan composite material, the volume ratio of the acidic solvent to zirconium acetate is 100:(1 - 3). For example, 100:1, 100:2, 100:3, or a range composed of any two of the aforementioned ratios.

[0068] In some embodiments, in the provided method for preparing a zirconium-crosslinked chitosan composite material, the acidic solvent is an aqueous acetic acid solution, and the acetic acid concentration in the aqueous acetic acid solution is 2 wt% - 5 wt%. For example, 2 wt%, 3 wt%, 4 wt%, 5 wt%, or a range composed of any two of the aforementioned values.

[0069] In some embodiments, there is provided the use of a zirconium-crosslinked chitosan composite material or a zirconium-crosslinked chitosan composite material prepared by the provided preparation method for defluorination in a solution.

[0070] In some embodiments, there is provided the use of a zirconium-crosslinked chitosan composite material or a zirconium-crosslinked chitosan composite material prepared by the provided preparation method for defluorination in fluorinated brine or fluorinated hydrochloric acid.

[0071] In some embodiments, in the fluorinated hydrochloric acid, the mass concentration of hydrochloric acid is 10% - 30%, and the concentration of fluorine element by mass ratio is 50 ppm - 4000 ppm.

[0072] In some embodiments, in the fluorinated brine, the salt content is greater than or equal to 15 g / L.

[0073] In some embodiments, there is provided a method for defluorination of fluorinated hydrochloric acid or fluorinated brine, comprising the following steps:

[0074] Contact at least one of the fluorinated hydrochloric acid and the fluorinated brine with a zirconium-crosslinked chitosan composite material or a zirconium-crosslinked chitosan composite material prepared by the provided preparation method.

[0075] In some embodiments, in the provided method for defluorination of fluorinated hydrochloric acid or fluorinated brine, in the fluorinated hydrochloric acid, the mass concentration of hydrochloric acid is 10% - 30%, and the concentration of fluorine element by mass ratio is 100 ppm - 1000 ppm.

[0076] In some embodiments, in the provided method for defluorination of fluorinated hydrochloric acid or fluorinated brine, in the fluorinated brine, the salt content is greater than or equal to 15 g / L.

[0077] The provided zirconium-crosslinked chitosan composite material has a primary defluorination rate of more than 85% for hydrofluoric hydrochloric acid, reaching up to more than 92%; three intermittent adsorptions can reduce the fluoride concentration in hydrofluoric hydrochloric acid from 1000 ppm to 0.45 ppm - 0.92 ppm. Through adsorption-desorption tests, the provided zirconium-crosslinked chitosan composite material shows good cyclic stability in hydrofluoric hydrochloric acid wastewater, and the adsorption performance in the 4th use is 98.4% of the first adsorption capacity. In addition, in acidic fluoride wastewater with a pH value of 4, the adsorption capacity of the zirconium-crosslinked chitosan defluorinating agent can reach 129.3 mg / g. In acidic fluoride wastewater with high-concentration chlorides (such as sodium chloride, potassium chloride, magnesium chloride, etc.), the adsorption capacities of the provided zirconium-crosslinked chitosan composite material reach 234.2 mg / g, 232.4 mg / g, and 300.0 mg / g respectively.

[0078] The preparation method of the provided zirconium-crosslinked chitosan composite material is simple, without the need for high temperature and high pressure, has strong operability, low equipment requirements, a short production cycle, and can be customized in shape. It is an acidic wastewater defluorinating agent with good industrial application prospects.

[0079] In order to make the purpose and advantages of the present invention clearer, the following further details the solution and its effects of the present invention in combination with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and shall not be used to limit the present invention. Unless otherwise specified, the following embodiments do not include other components except inevitable impurities. The reagents and instruments used in the embodiments are all conventional selections in the art unless otherwise specified. The experimental methods without specific conditions noted in the embodiments are carried out under conventional conditions, such as the conditions described in the literature, books, or the methods recommended by the manufacturers. The zirconium acetate raw material used in the examples and comparative examples was purchased from Tianjin Leviathan Technology Co., Ltd., with a purity of Zr content of 15.0 - 16.0% (v / v); the chitosan raw material was purchased from Shanghai Dipe Chemical Technology Co., Ltd., with a purity of D.D > 95%; the glutaraldehyde raw material was purchased from Kemart (Tianjin) Chemical Technology Co., Ltd., with a purity of 25% solution.

[0080] Example 1

[0081] (1) Preparation of zirconium-crosslinked chitosan defluorinating agent

[0082] Take 1 ml of zirconium acetate (Zr(CH3COO)4) and mix it evenly with 9 ml of 2% acetic acid, add 0.1 g of chitosan, and achieve physical crosslinking through magnetic stirring. Subsequently, add 0.5 ml of 25% (v / v) glutaraldehyde solution and continue stirring. Finally, pour the mixed solution into a petri dish, with the liquid level height about 0.5 cm. After drying at 60 °C for 3 h, the zirconium-crosslinked chitosan defluorinating agent is obtained.

[0083] (2) Characterization of zirconium-crosslinked chitosan defluorinating agent

[0084] The PXRD pattern of the zirconium-crosslinked chitosan defluorinating agent was determined using a powder X-ray diffractometer (PXRD, Rigaku X, Cu Kα radiation λ = 1.54 Å), with a scanning range of 3 - 90° and a scanning speed of 10° / min. The PXRD pattern of this product is as shown in Figure 1 Figure [ID number not provided], and the characteristic peaks (2θ, ±0.2°) are: 6.0 ± 0.2°, 25.8 ± 0.2°, 41.1 ± 0.2°, 58.1 ± 0.2°. By comparing with the standard card, it is proved that zirconium in the material exists in the chitosan skeleton in the form of zirconia crystals and partially free zirconium acetate.

[0085] The thermal properties were characterized using a thermogravimetric analyzer (temperature range: 303 K - 863 K, 20 K·min -1 , Mettler Toledo, Switzerland). The TG pattern is as shown in Figure 2 Figure [ID number not provided], and it does not decompose when the temperature is below 487 ± 5 K.

[0086] The infrared spectrum of the zirconium-crosslinked chitosan defluorinating agent was determined using Fourier transform infrared spectroscopy (Bruker Alpha FTIR, resolution of 4 cm -1 , and each spectrum was scanned 16 times). The infrared spectrum is as shown in Figure 3 Figure [ID number not provided], with a broad absorption band appearing at 3705 ± 2 - 2995 ± 2 cm -1 , and characteristic peaks at 1575 ± 2 cm -1 , 1454 ± 2 - 1406 ± 2 cm -1 , and 1035 ± 2 cm -1 . These characteristic peaks prove that the amino and hydroxyl functional groups of the raw material chitosan are well retained in the synthesized adsorbent, and the room-temperature crosslinking reaction does not damage the basic skeleton structure of chitosan.

[0087] (3) Application of the zirconium-crosslinked chitosan defluorinating agent

[0088] It should be noted that the specific figure numbers in the original text are not provided in the translation as they are not clear in the given content. You may need to fill in the correct figure numbers if applicable.Before adsorption, deionized water was used for oscillating washing to remove unreacted substances on the surface and then dried. An adsorption fluoride removal test was carried out using a water bath thermostatic oscillator. The adsorption temperature was room temperature of 273 K, the adsorption time was 2 h, and the oscillation speed was 300 rpm. During the primary adsorption process of the hydrochloric acid waste liquid containing fluoride, the adsorbent dosage was 100 g / L. During the primary adsorption process of the neutral wastewater containing fluoride, the adsorbent dosage was 8 g / L. During the primary defluorination process in high-concentration brine, the adsorbent dosage was 4 g / L. The defluorination agent obtained by this method had a fluoride removal rate of 88.5% for the primary adsorption of the hydrochloric acid wastewater containing fluoride. After three times of adsorption, the fluoride concentration in the hydrochloric acid containing fluoride could be reduced from 1000 ppm to 0.45 ppm. At the same time, the primary adsorption fluoride removal rate in the neutral wastewater could reach 97.8%. In the mixed acidic wastewater of 120 g / L MgCl2 and 1 g / L fluoride ion, the measured adsorption capacity of this defluorination agent was 225.0 mg / g. In the mixed acidic wastewater of 120 g / L KCl and 1 g / L fluoride ion, the measured adsorption capacity of this defluorination agent was 171.0 mg / g. In the mixed acidic wastewater of 120 g / L NaCl and 1 g / L fluoride ion, the measured adsorption capacity of this defluorination agent was 196.8 mg / g. For this defluorination agent, the removal rates for four cycles of use in the hydrochloric acid containing fluoride were 89.7%, 93.6%, 93.8%, and 88.4% respectively.

[0089] The Raman spectra of the above adsorbent before and after adsorption in the hydrochloric acid system containing fluoride were obtained using a time-gated Raman spectrometer (PicoRaman M3 / SampleCube, Timegate, Finland). The Raman spectra before and after adsorption are as Figure 4 shown, with the characteristics: having characteristic peaks at 507 ± 5 cm -1 , 791 ± 5 cm -1 , 1109 ± 5 cm -1 , 1594 ± 5 cm -1 , 2353 ± 5 cm -1 . There was no change in the Raman spectra of the material before and after adsorption, indicating the stability of the internal structure of the material.

[0090] Example 2

[0091] (1) Preparation of zirconium cross-linked chitosan defluorination agent

[0092] 2 ml of zirconium acetate (Zr(CH3COO)4) was taken and mixed evenly with 8 ml of 2% acetic acid, then 0.3 g of chitosan was added, and physical cross-linking was achieved through magnetic stirring. Subsequently, 0.5 ml of 25% (v / v) glutaraldehyde solution was added and stirring continued. Finally, the product was shaped using different-shaped molds and then dried at 60 °C for 12 h to obtain the zirconium cross-linked chitosan defluorination agent. The obtained zirconium cross-linked chitosan defluorination agent is as Figure 5 shown.

[0093] (2)Application of zirconium cross-linked chitosan defluorinating agent

[0094] Before adsorption, deionized water was used for oscillating washing to remove unreacted substances on the surface and then dried. The defluorination rate, adsorption capacity and recycling performance were detected by the same method as in Example 1.

[0095] The defluorination rate of the defluorinating agent obtained by this method for a single adsorption of fluorine-containing hydrochloric acid wastewater reached 87.1%. The defluorination rate for a single adsorption in neutral wastewater could reach 95.8%. In the mixed acidic wastewater of 120 g / L MgCl2 and 1 g / L fluoride ion, the measured adsorption capacity of this defluorinating agent was 190.0 mg / g. In the mixed acidic wastewater of 120 g / L KCl and 1 g / L fluoride ion, the measured adsorption capacity of this defluorinating agent was 151.2 mg / g. In the mixed acidic wastewater of 120 g / L NaCl and 1 g / L fluoride ion, the measured adsorption capacity of this defluorinating agent was 170.1 mg / g.

[0096] Example 3

[0097] (1)Preparation of zirconium cross-linked chitosan defluorinating agent

[0098] 1 ml of zirconium acetate (Zr(CH3COO)2) was taken and mixed evenly with 9 ml of 2% acetic acid, then 0.1 g of chitosan was added, and physical cross-linking was achieved by magnetic stirring. Subsequently, 0.5 ml of 25% (v / v) glutaraldehyde solution was added and stirring continued. Finally, the mixed solution was poured into a petri dish for drying by blowing. The zirconium cross-linked chitosan defluorinating agent was obtained after drying at 60 °C for 3 h.

[0099] (2)Application of zirconium cross-linked chitosan defluorinating agent

[0100] Before adsorption, deionized water was used for oscillating washing to remove unreacted substances on the surface and then dried. The defluorination rate, adsorption capacity and recycling performance were detected by the same method as in Example 1.

[0101] The defluorination agent obtained by this method has a defluorination rate of 85.1% for the first adsorption of hydrofluoric acid-containing wastewater. After three adsorptions, the fluorine concentration in hydrofluoric acid can be reduced from 1000 ppm to 1.2 ppm. At the same time, the defluorination rate for the first adsorption in neutral wastewater can reach 96.8%. In the mixed acidic wastewater containing 120 g / L MgCl2 and 1 g / L fluoride ions, the measured adsorption capacity of this defluorination agent is 204.0 mg / g. In the mixed acidic wastewater containing 120 g / L KCl and 1 g / L fluoride ions, the measured adsorption capacity of this defluorination agent is 161.2 mg / g. In the mixed acidic wastewater containing 120 g / L NaCl and 1 g / L fluoride ions, the measured adsorption capacity of this defluorination agent is 179.1 mg / g. For this defluorination agent, the removal rates for four cycles of use in hydrofluoric acid are 88.4%, 84.6%, 82.0%, and 80.5% respectively.

[0102] Example 4

[0103] (1) Preparation of zirconium cross-linked chitosan defluorination agent

[0104] Take 1 ml of zirconium acetate (Zr(CH3COO)4) and mix it evenly with 9 ml of 2% acetic acid. Add 0.3 g of chitosan and achieve physical cross-linking through magnetic stirring. Then add 0.5 ml of 25% (v / v) glutaraldehyde solution and continue stirring. Finally, pour the mixed solution into a petri dish and perform air drying. After drying at 60 °C for 3 h, the zirconium cross-linked chitosan defluorination agent is obtained.

[0105] (2) Application of zirconium cross-linked chitosan defluorination agent

[0106] Before adsorption, wash with deionized water by oscillation to remove unreacted substances on the surface and dry. Detect the defluorination rate using the same method as in Example 1.

[0107] The defluorination rate of the defluorination agent obtained by this method for the first adsorption of hydrofluoric acid-containing wastewater is 72.1%.

[0108] Example 5

[0109] (1) Preparation of zirconium cross-linked chitosan defluorination agent

[0110] Take 1 ml of zirconium acetate (Zr(CH3COO)4) and mix it evenly with 9 ml of 2% acetic acid. Add 0.1 g of chitosan and achieve physical cross-linking through magnetic stirring. Then add 0.3 ml of 25% (v / v) glutaraldehyde solution and continue stirring. Finally, pour the mixed solution into a petri dish and perform air drying. After drying at 60 °C for 3 h, the zirconium cross-linked chitosan defluorination agent is obtained.

[0111] (2) Application of zirconium cross-linked chitosan defluorination agent

[0112] Before adsorption, deionized water was used for oscillating washing to remove the unreacted substances on the surface and then dried. The detection of the defluorination rate was carried out by the same method as in Example 1.

[0113] The defluorination rate of the defluorizer obtained by this method for the first adsorption of the hydrofluoric acid-containing wastewater was 77.1%.

[0114] Comparative Example 1

[0115] (1) Preparation of zirconium-crosslinked chitosan defluorizer

[0116] 1.26 g of ZrOCl2•8H2O was taken and mixed evenly with 9 ml of 2% acetic acid, and 0.1 g of chitosan was added, and physical crosslinking was achieved by magnetic stirring. Subsequently, 0.5 ml of 25% (v / v) glutaraldehyde solution was added and stirring was continued. Finally, the mixed solution was poured into a petri dish for drying with forced air. After drying at 60 °C for 3 h, the zirconium-crosslinked chitosan defluorizer was obtained.

[0117] The defluorizer prepared by this method decomposed during the oscillating washing with deionized water, making the water body show an orange color and unable to achieve solid-liquid separation. Therefore, the material obtained by this method is not suitable for use as a defluorizer.

[0118] Comparative Example 2

[0119] (1) Preparation of zirconium-crosslinked chitosan defluorizer

[0120] 1 ml of zirconium acetate (Zr(CH3COO)4) was taken and mixed evenly with 9 ml of 2% acetic acid, and 0.1 g of chitosan was added, and physical crosslinking was achieved by magnetic stirring. The mixed solution was poured into a petri dish for drying with forced air. After drying at 60 °C for 3 h, the zirconium-crosslinked chitosan defluorizer was obtained.

[0121] The defluorizer prepared by this method swelled by absorbing water during the oscillating washing with deionized water and dissolved in hydrochloric acid, and solid-liquid separation could not be achieved. Therefore, the material obtained by this method is not suitable for use as a defluorizer.

[0122] Comparative Example 3

[0123] (1) Preparation of zirconium-crosslinked chitosan defluorizer

[0124] 1 ml of zirconium acetate (Zr(CH3COO)4) was taken and mixed evenly with 9 ml of 2% sodium hydroxide, and 0.1 g of chitosan was added. The chitosan could not be dissolved by magnetic stirring, and physical crosslinking could not be carried out between the two. The solid-liquid mixture was poured into a petri dish for drying with forced air. After drying at 60 °C for 3 h, the zirconium-crosslinked chitosan defluorizer was obtained.

[0125] The material obtained by this method has no adsorption capacity in hydrofluoric acid-containing hydrochloric acid.

[0126] Comparative Example 4

[0127] (1) Preparation of Lanthanum Crosslinked Chitosan Defluorinating Agent

[0128] Take 0.025 g of lanthanum acetate (La(CH3COO)3) and mix it evenly with 9 ml of 2% acetic acid. Add 0.1 g of chitosan and achieve physical crosslinking by magnetic stirring. Subsequently, add 0.5 ml of 25% (v / v) glutaraldehyde solution and continue stirring. Finally, pour the mixed solution into a petri dish with a liquid level height of about 0.5 cm. After drying at 60 °C for 3 h, the lanthanum crosslinked chitosan defluorinating agent is obtained.

[0129] The material obtained by this method has no adsorption capacity in hydrofluoric acid.

[0130] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0131] The above-described embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent should be subject to the appended claims, and the description and drawings can be used to explain the content of the claims.

Claims

1. A zirconium-crosslinked chitosan composite material, characterized in that, The infrared spectrum of the zirconium-crosslinked chitosan composite has characteristic peaks at 3705±2 cm -1 ~2995±2 cm -1 、2934±2 cm -1 、1575±2 cm -1 、1454±2 cm -1 ~1406±2 cm -1 and 1035±2 cm -1 .

2. The zirconium-crosslinked chitosan composite material according to claim 1, wherein The X-ray powder diffraction pattern of the zirconium cross-linked chitosan composite has characteristic diffraction peaks at the following 2θ (°) angles: 6.0 ± 0.2°, 25.8 ± 0.2°, 41.1 ± 0.2°, and 58.1 ± 0.2°.

3. The zirconium-crosslinked chitosan composite material according to claim 1, characterized in that, In the thermogravimetric analysis spectrum of the zirconium cross-linked chitosan composite, the decomposition temperature is 487 ± 5 K.

4. The zirconium-crosslinked chitosan composite material according to any one of claims 1 to 3, characterized in that, The Raman spectrum of the zirconium-crosslinked chitosan composite material has characteristic peaks at 507±5 cm -1 , 791±5 cm -1 , 1109±5 cm -1 , 1594±5 cm -1 and 2353±5 cm -1 .

5. A preparation method of a zirconium-crosslinked chitosan composite material, characterized in that, It includes the following steps: in the presence of an acidic solvent, zirconium acetate and chitosan are mixed for physical cross-linking, a cross-linking agent is added for chemical cross-linking reaction, and then it is dried to obtain the zirconium cross-linked chitosan composite; The infrared spectrum of the zirconium cross-linked chitosan composite has characteristic peaks at 3705±2 cm -1 ~2995±2 cm -1 , 2934±2 cm -1 , 1575±2 cm -1 , 1454±2 cm -1 ~1406±2 cm -1 , 1035±2 cm -1 .

6. The preparation method according to claim 5, characterized in that, Meet one or more of the following conditions: (1) The ratio of zirconium acetate to chitosan is (1 - 3) mL : (1 - 5) g; (2) In the step of adding the cross-linking agent for chemical cross-linking reaction, the final concentration of the cross-linking agent in the reaction system is 0.5% v / v - 1.5% v / v.

7. The preparation method according to claim 5, characterized in that, Meet one or more of the following conditions: (1) The X-ray powder diffraction pattern of the zirconium cross-linked chitosan composite has characteristic diffraction peaks at the following 2θ (°) angles: 6.0 ± 0.2°, 25.8 ± 0.2°, 41.1 ± 0.2°, and 58.1 ± 0.2°; (2) In the thermogravimetric analysis spectrum of the zirconium cross-linked chitosan composite, the decomposition temperature is 487 ± 5 K; (3)The Raman spectrum of the zirconium-crosslinked chitosan composite has characteristic peaks at 507±5 cm -1 , 791±5 cm -1 , 1109±5 cm -1 , 1594±5 cm -1 and 2353±5 cm -1 ; (4) The cross-linking agent includes one or more of glutaraldehyde and epichlorohydrin; (5) The volume ratio of the acidic solvent to zirconium acetate is 100 : (1 - 3); (6) The acidic solvent is an acetic acid aqueous solution, and the acetic acid concentration in the acetic acid aqueous solution is 2 wt% - 5 wt%.

8. The application of the zirconium cross-linked chitosan composite according to any one of claims 1 - 4 or the zirconium cross-linked chitosan composite prepared by the preparation method according to any one of claims 5 - 7 in defluorination in solution; Optionally, the application of the zirconium cross-linked chitosan composite in defluorination of fluorinated brine or fluorinated hydrochloric acid; Optionally, in the fluorinated hydrochloric acid, the mass concentration of hydrochloric acid is 10% - 30%, and the concentration of fluorine element by mass is 50 ppm - 4000 ppm; Optionally, in the fluorinated brine, the salt content is greater than or equal to 15 g / L.

9. A method for defluorination of fluorine-containing hydrochloric acid or fluorine-containing brine, characterized in that, It includes the following steps: At least one of fluorinated hydrochloric acid and fluorinated brine is contacted with the zirconium cross-linked chitosan composite according to any one of claims 1 - 4 or the zirconium cross-linked chitosan composite prepared by the preparation method according to any one of claims 5 - 7.

10. The method according to claim 9, wherein Meet one or more of the following conditions: (1) In the fluorinated hydrochloric acid, the mass concentration of hydrochloric acid is 10% - 30%, and the concentration of fluorine element by mass is 100 ppm - 1000 ppm; (2) In the fluorinated brine, the salt content is greater than or equal to 15 g / L.

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