A biomass waste-based adsorbent intermediate carrier, a preparation method and application thereof

Abstract

The application provides a biomass waste-based adsorbent intermediate carrier and a preparation method and application thereof. The adsorbent intermediate carrier comprises biomass waste and polymethyl glycidyl methacrylate grafted on the biomass waste; the adsorbent intermediate carrier takes the biomass waste as a basic carrier and takes the polymethyl glycidyl methacrylate as a surface grafting polymer, has the advantage of high grafting rate, and further makes the surface of the obtained adsorbent intermediate carrier rich in epoxy groups; a variety of target functional ligands can be introduced for functional modification through ring-opening reaction of the epoxy groups, and the obtained adsorbent after functional modification has the advantages of fast adsorption rate and high adsorption capacity.

Description

Technical Field

[0001] This invention belongs to the field of adsorbent technology, specifically relating to an adsorbent intermediate carrier based on biomass waste, its preparation method, and its application. Background Technology

[0002] In recent years, biosorption methods, which utilize various natural or biomass waste resources or derivatives as adsorbents, have developed rapidly. These biosorbents are not only non-toxic, harmless, and biocompatible, but also inexpensive. Furthermore, the used biosorbents are biodegradable, making them excellent green adsorbent materials. Biomass waste is abundant and inexpensive; however, if not utilized properly, it will lead to urban environmental problems.

[0003] Currently, an increasing number of biomass wastes are being chemically modified for use as adsorbents, representing a significant pathway for waste resource utilization. Cellulose is a major component of biomass waste; however, hydrogen bonds form within or between cellulose macromolecules, binding the active functional group hydroxyl (-OH). Furthermore, -OH exhibits poor adsorption capacity and selectivity for most metal ions. Therefore, modifying cellulose through necessary chemical methods to improve its adsorption performance is essential.

[0004] Polyglycidyl methacrylate (PGMA) contains a large number of epoxy groups, which facilitate the modification of various functional ligands (such as amino, hydroxyl, and anhydride groups) through ring-opening reactions. It shows promising applications as a catalyst support, drug and gene carrier, and template for preparing complex multilevel structural materials. PGMA polymer microspheres are also excellent adsorbent carriers because PGMA possesses a large number of highly reactive functional groups, namely epoxy groups. Through the ring-opening reaction of epoxy groups, various target functional ligands can be introduced, thereby improving the adsorption performance of PGMA adsorbent materials for target substances. Cerium salts (Ce...) 4+ Graft polymerization initiated by cerium salts has a wide range of applications in the surface modification and alteration of natural or synthetic polymers, such as cellulose, starch, and polyvinyl alcohol. The grafted substrate should contain active hydroxyl or thiol functional groups so that the cerium salt can undergo an oxidation reaction to generate free radicals.

[0005] CN110124623A discloses a modified corn stalk cellulose adsorbent, its preparation method, and its uses. The modified corn stalk cellulose adsorbent has an amination-modified cellulose polymer MCC-g-GMA-DETA as its functional component. Its preparation method includes (1) obtaining corn stalk microcrystalline cellulose; (2) grafting corn stalk microcrystalline cellulose; and (3) amination of the graft copolymer. This modified corn stalk cellulose adsorbent is mainly used in wastewater treatment processes involving the specific deposition of Cu. 2+ Ni 2+ and Cd2+ The adsorption and removal process effectively removes three heavy metal ions, achieving maximum adsorption capacities of 196 mg / g, 180 mg / g, and 270 mg / g at room temperature, respectively. The adsorption rate is rapid, and the material can be regenerated and reused multiple times. It features inexpensive and readily available raw materials, biodegradability, low toxicity, safe use, and environmental friendliness, thus broadening the application areas of corn stalks and contributing to the efficient resource utilization of agricultural waste.

[0006] However, most cerium salt-induced graft polymerization reactions, including the aforementioned existing technologies, are limited to natural or synthetic polymer substrates, and graft polymerization reactions on the surface of biomass waste are rarely reported.

[0007] Therefore, developing an adsorbent intermediate carrier based on biomass waste that is easy to subsequently functionalize is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide an adsorbent intermediate carrier based on biomass waste, its preparation method, and its application. The adsorbent intermediate carrier uses biomass waste as a matrix and grafts polyglycidyl methacrylate onto it. This not only has the advantages of low cost, wide availability of raw materials, and being environmentally friendly, but the resulting adsorbent intermediate carrier also facilitates subsequent functionalization modification. Furthermore, the adsorbent obtained after functionalization modification has the advantages of fast adsorption rate and high adsorption capacity.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides an adsorbent intermediate carrier based on biomass waste, the adsorbent intermediate carrier comprising biomass waste and polyglycidyl methacrylate grafted onto the biomass waste.

[0011] The adsorbent intermediate carrier provided by this invention uses various biomass wastes as the basic carrier and polyglycidyl methacrylate (PGMA) as the surface graft polymer. The two are combined, and the molecular chains of the polyglycidyl methacrylate are grafted onto the surface of the biomass waste in a "whisker-like" manner to form the adsorbent intermediate carrier. Since the surface of the biomass waste is rich in hydroxyl groups, it is conducive to the grafting reaction with the PGMA monomer, which can effectively improve the grafting rate of PGMA on the surface of the biomass waste. This makes the surface of the obtained adsorbent intermediate carrier rich in epoxy groups, and then various target functional ligands can be introduced for functional modification through the ring-opening reaction of the epoxy groups, such as amino, mercapto, carboxyl, etc. The adsorbent obtained after functional modification has the advantages of fast adsorption rate and high adsorption capacity.

[0012] Preferably, the biomass waste includes any one or a combination of at least two of the following: corn stalks, rice stalks, wheat stalks, wheat bran, rice husks, corn cobs, tea dregs, sugarcane bagasse, fruit peels, waste paper products, or waste cotton and linen products.

[0013] Preferably, the grafting rate of polyglycidyl methacrylate on the biomass waste is 5% to 90%, such as 10%, 20%, 30%, 40%, 50%, 60%, 70%, or 80%.

[0014] In a second aspect, the present invention provides a method for preparing an adsorbent intermediate support as described in the first aspect, the preparation method comprising the following steps:

[0015] (1) Alkali treatment is carried out on biomass waste to obtain alkalized biomass waste;

[0016] (2) React the alkalized biomass waste obtained in step (1), glycidyl methacrylate monomer, and initiator to obtain the adsorbent intermediate carrier.

[0017] The method for preparing the adsorbent intermediate carrier provided by this invention first involves alkalizing the biomass waste. The purpose of alkalization is to induce swelling in the biomass waste, thereby disrupting the internal hydrogen bond structure and exposing more bound hydroxyl groups, effectively improving the accessibility of functional groups. This step not only enhances the adsorption capacity for metal ions after the adsorbent is formed but also further improves the grafting rate of PGMA, thus increasing the content of surface active functional groups (epoxy groups) in the final adsorbent intermediate. Then, the GMA monomer is polymerized and grafted using an initiation grafting method. The grafting method on biomass waste after alkalization treatment not only results in a significantly higher content of epoxy groups on the surface of the obtained adsorbent intermediate compared to that obtained by ordinary chemical modification, but also allows for control of the PGMA chain length and grafting rate by adjusting reaction conditions such as the amount of GMA monomer, the amount and concentration of the initiator, and the polymerization temperature. This results in an active intermediate carrier of waste biomass adsorbent with grafted "whisker-like" PGMA polymer chains, which is convenient for subsequent functionalization modification when used as an adsorbent. Furthermore, the adsorbent obtained after functionalization modification also has the advantages of fast adsorption rate and high adsorption capacity.

[0018] Preferably, step (1) further includes a pretreatment step of biomass waste before the alkalization treatment;

[0019] Preferably, the pretreatment includes the steps of crushing, screening, washing and drying the biomass waste.

[0020] Preferably, the alkalization treatment method in step (1) specifically includes: mixing biomass waste with an alkaline aqueous solution to complete the alkalization treatment. Preferably, the alkaline aqueous solution includes an aqueous sodium hydroxide solution.

[0021] Preferably, based on a volume of 1L of the sodium hydroxide aqueous solution, the number of moles of sodium hydroxide is 0.1 to 5 mol, for example, 0.5 mol, 1 mol, 2 mol, 3 mol or 4 mol, and more preferably 0.5 to 2 mol / L.

[0022] Preferably, the mixing temperature is 20–100°C, such as 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, or 90°C, and more preferably 40–50°C.

[0023] Preferably, the mixing time is 1 to 48 hours, such as 5 hours, 10 hours, 15 hours, 20 hours, 25 hours, 30 hours, 35 hours, 40 hours or 45 hours, and more preferably 6 to 24 hours.

[0024] Preferably, the initiator in step (2) comprises a cerium salt.

[0025] Preferably, the cerium salt comprises cerium ammonium nitrate.

[0026] It should be noted that in actual operation, cerium ammonium nitrate needs to be dissolved in nitric acid solution to obtain cerium ammonium nitrate and nitric acid solution.

[0027] Preferably, the concentration of cerium ammonium nitrate in the nitric acid solution of the cerium ammonium nitrate is 0.005 to 0.5 mol / L, for example, 0.007 mol / L, 0.009 mol / L, 0.11 mol / L, 0.13 mol / L, 0.15 mol / L, 0.1 mol / L, or 0.3 mol / L, and more preferably 0.05 to 0.5 mol / L.

[0028] Preferably, the concentration of nitric acid in the nitric acid solution is 0.01 to 5 mol / L, for example, 0.05 mol / L, 0.1 mol / L, 0.5 mol / L, 1 mol / L, 2 mol / L, 3 mol / L or 4 mol / L.

[0029] Preferably, the reaction in step (2) is carried out under a protective gas atmosphere, and more preferably under a nitrogen atmosphere.

[0030] Preferably, the temperature of the reaction in step (2) is 50 to 100°C, such as 60°C, 70°C, 80°C or 90°C, and more preferably 60 to 70°C.

[0031] Preferably, the reaction time in step (2) is 2 to 24 hours, such as 5 hours, 10 hours, 15 hours or 20 hours, and more preferably 4 to 8 hours.

[0032] As a preferred embodiment of the present invention, the preparation method of the adsorbent intermediate support specifically includes the following steps:

[0033] (1a) The biomass waste is successively crushed, screened, washed and dried to obtain pretreated biomass waste;

[0034] (1b) The pretreated biomass waste obtained in step (1a) is mixed with an alkaline aqueous solution at 40-50°C for 2-48 hours, filtered, washed and dried to obtain alkalized biomass waste.

[0035] (2) Under protective gas conditions, the biomass waste after alkalization treatment obtained in step (1b) is mixed with water, an initiator and glycidyl methacrylate monomer are added, and the mixture is reacted at 50-100°C for 2-24 hours. After washing, the intermediate carrier of the adsorbent is obtained.

[0036] Thirdly, the present invention provides an adsorbent comprising an adsorbent intermediate carrier and a ligand as described in the first aspect.

[0037] Preferably, the ligand comprises any one or a combination of at least two of the following: amine-containing ligands, thiol-containing ligands, or anhydride-containing ligands.

[0038] Preferably, the ligand comprises any one or a combination of at least two of ethylenediamine, polyvinylamine, aminothiourea, thiols, ethylenedithiol, succinic anhydride, or succinic anhydride.

[0039] Fourthly, the present invention provides an application of the adsorbent as described in the third aspect in air filtration or wastewater treatment.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] The adsorbent intermediate carrier based on biomass waste provided by this invention includes biomass waste and polyglycidyl methacrylate grafted onto the biomass waste; the adsorbent intermediate carrier uses various biomass wastes as the basic carrier and PGMA as the surface graft polymer, so that the molecular chains of PGMA are grafted onto the biomass waste in a "whisker-like" manner; the surface of the adsorbent intermediate carrier is rich in epoxy groups, and various target functional ligands can be introduced for functional modification through the ring-opening reaction of epoxy groups, such as amino, thiol, carboxyl, etc., and the adsorbent obtained after functional modification has the advantages of fast adsorption rate and high adsorption capacity. Detailed Implementation

[0042] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0043] Example 1

[0044] An adsorbent intermediate carrier based on biomass waste, comprising corn stalks and polyglycidyl methacrylate grafted onto corn stalks;

[0045] Its preparation method includes the following steps:

[0046] (1) The corn stalks are crushed, sieved, washed and dried in sequence to obtain pretreated corn stalks;

[0047] (2) The pretreated corn stalks obtained in step (1) and sodium hydroxide aqueous solution (sodium hydroxide concentration is 0.5mol / L) were mixed at 45℃ for 20h according to a solid-liquid ratio (g:mL) of 1:50. After centrifugation, the mixture was washed with water until it was nearly neutral and dried to obtain the alkalized corn stalks.

[0048] (3) Add corn stalks and deionized water obtained in step (2) with a solid-liquid ratio (g:mL) of 1:800 to the reactor. Place the reactor in a constant temperature water bath at 65°C and continuously purge with nitrogen to remove oxygen. Add 10mL of cerium ammonium nitrate solution (cerium ammonium nitrate concentration is 0.1mol / L, nitric acid concentration is 1mol / L) and 10mL of glycidyl methacrylate, and react at 65°C for 8h. Wash and dry to obtain the adsorbent intermediate carrier.

[0049] Example 2

[0050] An adsorbent intermediate carrier based on biomass waste, comprising corn stalks and polyglycidyl methacrylate grafted onto corn stalks;

[0051] Its preparation method includes the following steps:

[0052] (1) Rice straw is crushed, sieved, washed and dried in sequence to obtain pretreated corn straw;

[0053] (1) The pretreated corn straw obtained in step (1) and sodium hydroxide aqueous solution (sodium hydroxide concentration is 1mol / L) were mixed at room temperature for 10h according to a solid-liquid ratio (g:mL) of 1:50. The mixture was then centrifuged, washed with water until near neutral and dried to obtain alkalized rice straw.

[0054] (2) Add the alkalized rice straw and deionized water obtained in step (2) with a solid-liquid ratio (g:mL) of 1:75 to the reactor. Place the reactor in a constant temperature water bath at 70°C and continuously purge with nitrogen to remove oxygen. Add 8 mL of cerium ammonium nitrate solution (cerium ammonium nitrate concentration is 0.1 mol / L, nitric acid concentration is 1 mol / L) and 15 mL of glycidyl methacrylate. React at 70°C for 4 h. Wash and dry to obtain the adsorbent intermediate carrier.

[0055] Example 3

[0056] An adsorbent intermediate carrier based on biomass waste is different from Example 1 only in that the reaction temperature in step (3) is 70°C and the reaction time is 24h. Other substances, steps and parameters are the same as in Example 1.

[0057] Example 4

[0058] An adsorbent intermediate carrier based on biomass waste is different from Example 1 only in that the reaction temperature in step (3) is 100°C and the reaction time is 2h. Other substances, steps and parameters are the same as in Example 1.

[0059] Comparative Example 1

[0060] An adsorbent intermediate carrier based on biomass waste, comprising corn stalks and polyglycidyl methacrylate grafted onto corn stalks;

[0061] Its preparation method includes the following steps:

[0062] (1) The corn stalks are crushed, sieved, washed and dried in sequence to obtain pretreated corn stalks;

[0063] (2) Add the pretreated corn stalks and deionized water obtained in step (1) with a solid-liquid ratio (g:mL) of 1:800 to the reactor. Place the reactor in a constant temperature water bath at 65°C and continuously purge with nitrogen to remove oxygen. Add 10 mL of cerium ammonium nitrate solution (cerium ammonium nitrate concentration is 0.1 mol / L, nitric acid concentration is 1 mol / L) and 10 mL of glycidyl methacrylate, and react at 65°C for 8 h. Wash and dry to obtain the adsorbent intermediate carrier.

[0064] Performance testing:

[0065] The adsorbent intermediate carriers obtained in Examples 1-4 and Comparative Example 1 were mixed with 10% polyethyleneimine (number average molecular weight of 10,000) at 80°C for 6 hours to obtain the adsorbent, and the following tests were performed.

[0066] (1) N content: The N content in the adsorbent is tested, and the unit is mmol / g;

[0067] (2) Adsorption rate: The adsorbent was added to a Pd(II) solution of a certain concentration, and samples were taken at different times to test the Pd(II) concentration in the solution. The adsorption amount of Pd(II) at different times was calculated and the kinetic adsorption curve was plotted to obtain the time required to reach adsorption equilibrium.

[0068] (3) Saturated adsorption capacity: The adsorbent was added to Pd(II) solutions of different concentrations. After adsorption equilibrium was reached, the concentration of Pd(II) in the solution was tested. The equilibrium adsorption capacity of Pd(II) in Pd(II) solutions of different concentrations was calculated and the thermodynamic adsorption equilibrium curve was plotted to obtain the saturated adsorption capacity of Pd(II).

[0069] The core-shell structured adsorbent intermediate supports provided in Examples 1-4 and Comparative Example 1 were tested according to the above test methods. The test results are shown in Table 1.

[0070] Table 1

[0071]

[0072] According to the data in Table 1:

[0073] The adsorbents obtained by combining the adsorbent carriers provided in Examples 1-4 with ammonium ion ligands have a nitrogen content of 4.2-6.3 mmol / g, indicating a high ligand grafting rate; the adsorption equilibrium time for Pd(II) is 15 min, indicating a fast adsorption rate; and the saturated adsorption capacity for Pd(II) can reach 2.9-4.2 mmol / g, indicating a high adsorption capacity.

[0074] The adsorbent obtained by combining the unalkalized adsorbent intermediate support with ammonium ion ligands provided in Comparative Example 1 had a low ligand grafting rate and thus a poor adsorption effect.

[0075] The applicant declares that this invention illustrates an adsorbent intermediate carrier based on biomass waste, its preparation method, and its application through the above embodiments. However, this invention is not limited to the above embodiments, meaning that this invention does not necessarily rely on the above embodiments for implementation. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials for the product, addition of auxiliary components, and selection of specific methods, etc., all fall within the protection and disclosure scope of this invention.

Claims

1. An application of an adsorbent based on biomass waste in the adsorption and removal of Pd(II) in hydrometallurgy or wastewater treatment, characterized in that, The adsorbent comprises an adsorbent intermediate support and a ligand; the ligand comprises polyethyleneimine; The adsorbent intermediate carrier comprises biomass waste and polyglycidyl methacrylate grafted onto the biomass waste; The biomass waste includes any one or a combination of at least two of the following: corn stalks, rice stalks, wheat stalks, wheat bran, corn cobs, tea dregs, sugarcane bagasse, fruit peels, waste paper products, and waste cotton and linen products. The preparation method of the adsorbent intermediate support includes the following steps: (1) Alkali treatment of biomass waste to obtain alkalized biomass waste; (2) React the alkalized biomass waste obtained in step (1), glycidyl methacrylate monomer, and initiator to obtain the adsorbent intermediate carrier; The initiator includes cerium ammonium nitrate.

2. The application according to claim 1, characterized in that, The grafting rate of polyglycidyl methacrylate on the biomass waste is 5-90%.

3. The application according to claim 1, characterized in that, Step (1) includes a pretreatment step of biomass waste before alkalization.

4. The application according to claim 3, characterized in that, The pretreatment includes the steps of crushing, screening, washing and drying the biomass waste in sequence.

5. The application according to claim 1, characterized in that, The alkalization treatment method in step (1) includes: mixing biomass waste with an alkaline aqueous solution to complete the alkalization treatment.

6. The application according to claim 5, characterized in that, The alkaline aqueous solution includes an aqueous solution of sodium hydroxide.

7. The application according to claim 5, characterized in that, The mixing temperature is 20~100℃.

8. The application according to claim 7, characterized in that, The mixing temperature is 40~50℃.

9. The application according to claim 5, characterized in that, The mixing time is 2 to 48 hours.

10. The application according to claim 9, characterized in that, The mixing time is 6 to 24 hours.

11. The application according to claim 1, characterized in that, The reaction described in step (2) is carried out under protective gas conditions.

12. The application according to claim 11, characterized in that, The reaction described in step (2) is carried out under nitrogen protection.

13. The application according to claim 1, characterized in that, The reaction temperature in step (2) is 50~100℃.

14. The application according to claim 13, characterized in that, The reaction temperature in step (2) is 60~70℃.

15. The application according to claim 1, characterized in that, The reaction time in step (2) is 2 to 24 hours.

16. The application according to claim 15, characterized in that, The reaction time in step (2) is 4 to 8 hours.

17. The application according to claim 1, characterized in that, The specific preparation method of the adsorbent intermediate support includes the following steps: (1a) The biomass waste is crushed, screened, washed and dried in sequence to obtain pretreated biomass waste; (1b) The pretreated biomass waste obtained in step (1a) is mixed with an alkaline aqueous solution at 40-50°C for 2-48 hours, filtered, washed and dried to obtain alkalized biomass waste; (2) Under protective gas conditions, the biomass waste after alkalization treatment obtained in step (1b) is mixed with water, an initiator and glycidyl methacrylate monomer are added, and the mixture is reacted at 50~100℃ for 2~24 h. After washing and drying, the intermediate carrier of the adsorbent is obtained.

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