A chemical modification method for improving the heavy metal adsorption performance of loofah

Abstract

The present invention discloses a chemical modification method for improving the heavy metal adsorption performance of loofah, comprising the steps of: (1) modifying the carboxyl group of the loofah pretreated with alkali solution and loading nano-alumina particles on the surface to achieve composite modification of the loofah and introduce double bonds to obtain Al 2 O 3 ‑loofah composite material; (2) through Al 2 O 3 The invention discloses a double-bond cross-linked grafted poly-4-vinylpyridine of a loofah composite material, and realizes cross-linking modification and functional modification of the loofah at the same time. The invention adopts two steps to complete the modification of the loofah, and the modification method is simple to operate, and can realize the effects of functional modification, composite modification and cross-linking modification of the loofah at the same time, thereby significantly improving the adsorption efficiency and capacity of the loofah for heavy metal ions.

Description

Technical Field

[0001] The invention relates to the technical field of solid adsorbents, in particular to a chemical modification method for improving the heavy metal adsorption performance of loofah. Background Art

[0002] Luffa has a three-dimensional network structure in an aggregated state, and the internal fibers are crisscrossed to form abundant pores and channels, so it has become an important research object for heavy metal adsorption materials. Although luffa itself has certain adsorption properties, its original adsorption efficiency and capacity are relatively low, which makes it difficult to meet the needs of efficient treatment of heavy metal wastewater. In addition, luffa needs to withstand various complex environmental conditions in practical applications, such as pH changes, temperature fluctuations, etc. The original luffa may be prone to degradation or failure under these conditions, affecting its adsorption performance and service life. The chemical modification of luffa is an important means to improve its heavy metal adsorption performance, improve stability and expand its application field, but the existing modification technology has limited improvement effects or requires complicated processes. Summary of the invention

[0003] In response to the above technical needs, the present invention provides a chemical modification method for improving the heavy metal adsorption performance of loofah, with the aim of solving the problem of how to reduce the modification steps to obtain a modified loofah with higher heavy metal ion adsorption efficiency and capacity.

[0004] The technical scheme of the present invention is as follows: A chemical modification method for improving the heavy metal adsorption performance of loofah comprises the following steps:

[0005] (1) Carboxyl modification was performed on the luffa pretreated with alkali solution and nano-alumina particles were loaded on the surface to achieve composite modification of the luffa and introduce double bonds to obtain Al2O3-luffa composite material;

[0006] (2) Through the double bond cross-linking grafting of poly (4-vinylpyridine) on the Al2O3-loofah composite material, the cross-linking modification and functional modification of the loofah were achieved simultaneously.

[0007] Furthermore, the step (1) specifically comprises adding the alkali-pretreated loofah, itaconic acid and p-toluenesulfonic acid to a dimethyl sulfoxide solution, carrying out a carboxyl modification reaction for a period of time, and then adding aluminum oxide nanoparticles, and continuing to stir the reaction, wherein the ratio of the alkali-pretreated loofah, itaconic acid and aluminum oxide nanoparticles is 1g: (2-4)g: (0.3-0.7)g.

[0008] Furthermore, in step (1), the carboxyl modification reaction is carried out at 50-80° C. with stirring for 3-6 hours.

[0009] Furthermore, in step (1), after adding the aluminum oxide nanoparticles, the mixture is stirred and reacted at 50-80° C. for 3-6 hours.

[0010] Furthermore, the step (2) specifically comprises immersing the Al2O3-loofah composite material in a solution containing 4-vinylpyridine monomer. N , N -dimethylformamide solution, and then add initiator azobisisobutyronitrile under protective atmosphere to carry out cross-linking polymerization reaction.

[0011] Furthermore, the mass ratio of the Al2O3-loofah composite material to the 4-vinylpyridine monomer is 1:(0.5-2).

[0012] Further, the 4-vinylpyridine monomer is dissolved N , N -The concentration of dimethylformamide solution is 10~60g / L.

[0013] Furthermore, the mass ratio of the 4-vinylpyridine monomer to the initiator azobisisobutyronitrile is (30-100):1.

[0014] Furthermore, the cross-linking polymerization reaction in step (2) is carried out at 50-100° C. for 10-30 hours, and after the reaction, the modified loofah is treated with N , N -Dimethylformamide, deionized water, and repeated washing and drying.

[0015] Furthermore, the alkaline solution pretreatment is to soak the loofah in a 2% to 15% NaOH aqueous solution, stir and treat it at 60 to 100° C. for 1 to 5 hours, and then wash it with deionized water until it is neutral.

[0016] The present invention firstly uses itaconic acid containing double bonds and multiple carboxyl groups as a "bridge", and through the esterification reaction between the carboxyl group and the hydroxyl group, the "bridge" is connected to the loofah on one side and the Al2O3 nanoparticles on the other side, thereby realizing the composite modification of the loofah and introducing a large number of double bonds. Furthermore, 4-vinylpyridine is used as a monomer, and the Al2O3-loofah composite material rich in double bonds is prepared as a cross-linking agent. Through cross-linking copolymerization, the cross-linking modification of the loofah is realized, and a large number of chemically active pyridine ring N atoms (which can form stable complexes with heavy metals) are introduced, bringing new functional properties to the loofah.

[0017] The advantages of the present invention compared with the prior art are:

[0018] (1) The modification method of the loofah provided by the present invention is simple and efficient, integrating functional modification, composite modification and cross-linking modification, thereby comprehensively improving the comprehensive performance of the loofah.

[0019] (2) The present invention can give full play to the synergistic adsorption effect of loofah itself, Al2O3 nanoparticles and polyvinyl pyridine on heavy metal ions through multi-effect modification (compounding, cross-linking, functionalization), thereby greatly improving the adsorption efficiency and adsorption capacity of heavy metal ions.

[0020] (3) The modified loofah prepared by the present invention not only has excellent heavy metal adsorption performance, but also effectively enhances the structural stability of the loofah through cross-linking modification, thereby improving its practical value and environmental adaptability. DETAILED DESCRIPTION

[0021] The present invention will be further described below in conjunction with the embodiments, but are not intended to limit the present invention.

[0022] Example 1

[0023] A chemical modification method for improving the heavy metal adsorption performance of loofah comprises the following steps:

[0024] (1) Composite modification and simultaneous introduction of double bonds

[0025] After peeling and removing the seeds from the ripe loofah fruit, immerse it in distilled water and squeeze it several times until no impurities fall off and the color changes. Then immerse the loofah in new distilled water again, changing the water every 3 hours, take it out after 12 hours, dry it naturally, and cut the loofah into 0.3 cm samples. Soak the sample in 10% NaOH aqueous solution, stir it at 80℃ for 4 hours, take it out, wash it with distilled water until it is neutral, and dry it for later use.

[0026] 1g of loofah pretreated with alkali solution was weighed and added to 200ml of dimethyl sulfoxide, and then 3g of itaconic acid and 0.15g of p-toluenesulfonic acid were added in sequence. After the reaction solution was stirred at 60°C for 4h, 0.5g of aluminum oxide nanoparticles was added thereto, and the reaction was continued at 60°C for 4h. After the reaction, the double-bonded Al2O3-loofah composite material was repeatedly washed with deionized water and dried.

[0027] (2) Cross-linking modification and functional modification

[0028] The Al2O3-loofah composite material rich in double bonds prepared in step (1) was immersed in 100 ml of N , N -dimethylformyl, add 1g of 4-vinylpyridine monomer, and add 0.02g of azobisisobutyronitrile under nitrogen protection, cross-link and polymerize at 70°C for 25h under nitrogen protection, and then use N , N The multi-effect chemically modified loofah is obtained by repeatedly washing with dimethylformamide and deionized water and drying.

[0029] The adsorption performance test experiment of the multi-effect chemically modified loofah prepared in this embodiment 1 is as follows:

[0030] Prepare 100 mL of an aqueous solution with a lead ion concentration of 100 mg / L (lead nitrate as a reagent) in a flask, adjust the solution pH to 7 with 0.1 M NaOH, add the prepared multi-effect chemically modified loofah, and then adsorb for 3 hours at 200 rpm in a constant temperature oscillator at 25°C. After adsorption, take the upper clear liquid, determine the lead ion concentration in the clear liquid by ICP-OES, and calculate the adsorption amount of lead ions by the adsorbent material by the following formula ( Q , mg / g), and the results are listed in Table 1.

[0031] Q =( C 0 - C t ) V / M

[0032] Q is the adsorption amount (g / g); C 0 is the initial concentration of heavy metal ions (mg / L); C t is the concentration of heavy metal ions after adsorption (mg / L); V is the volume of the solution (L); M is the mass of the adsorbent (mg).

[0033] Example 2

[0034] The difference between this example and example 1 is that 2 g of itaconic acid is added in step (1) of this example. The adsorption performance of the product is measured according to the adsorption performance experiment of the product in example 1, and the results are listed in Table 1.

[0035] Example 3

[0036] The difference between this example and example 1 is that 4 g of itaconic acid is added in step (1) of this example. The adsorption performance of the product is measured according to the adsorption performance experiment of the product in example 1, and the results are listed in Table 1.

[0037] Example 4

[0038] The difference between this embodiment and embodiment 1 is that 0.3 g of aluminum oxide nanoparticles are added in step (1) of this embodiment. The adsorption performance of the product is measured according to the adsorption performance experiment of the product in embodiment 1, and the results are listed in Table 1.

[0039] Example 5

[0040] The difference between this embodiment and embodiment 1 is that 0.7 g of aluminum oxide nanoparticles are added in step (1) of this embodiment. The adsorption performance of the product is measured according to the adsorption performance experiment of the product in embodiment 1, and the results are listed in Table 1.

[0041] Example 6

[0042] The difference between this embodiment and embodiment 1 is that 0.5 g of 4-vinylpyridine monomer is added in step (2) of this embodiment. The adsorption performance of the product is measured according to the adsorption performance experiment of the product in embodiment 1, and the results are listed in Table 1.

[0043] Example 7

[0044] The difference between this embodiment and embodiment 1 is that 2 g of 4-vinylpyridine monomer is added in step (2) of this embodiment. The adsorption performance of the product is measured according to the adsorption performance experiment of the product in embodiment 1, and the results are listed in Table 1.

[0045] Comparative Example 1

[0046] A method for preparing itaconic acid-modified loofah sponge. The difference between this comparative example and Example 1 is that no aluminum oxide nanoparticles are added in step (1) of this example, and no step (2) is included. The adsorption performance of the product is measured according to the adsorption performance experiment of the product in Example 1, and the results are listed in Table 1.

[0047] Comparative Example 2

[0048] A method for preparing an Al2O3-loofah composite material, wherein the steps are the same as step (1) in Example 1, but without step (2). The adsorption performance of the product is measured according to the adsorption performance experiment of the product in Example 1, and the results are listed in Table 1.

[0049] Comparative Example 3

[0050] A method for preparing polyvinylpyridine cross-linked modified loofah, the difference between this comparative example and Example 1 is that no aluminum oxide nanoparticles are added in step (1) of this example. The adsorption performance of the product is measured according to the adsorption performance experiment of the product in Example 1, and the results are listed in Table 1.

[0051] Table 1 Adsorption of lead ions by the multi-effect modified loofahs prepared in Examples 1-7 and Comparative Examples 1-3

[0052]

[0053] It can be seen from the results of the comparative example that the multi-effect modified loofah prepared by the present invention cleverly combines the characteristics of loofah itself, the advantages of Al2O3 nanoparticles and the functions of polyvinyl pyridine, realizes efficient synergistic adsorption of heavy metal ions, and significantly improves the adsorption capacity of lead ions.

Claims

1. A chemical modification method for improving the heavy metal adsorption performance of loofah, characterized in that, The following steps are involved: (1) Carboxyl modification is performed on the luffa pretreated with alkali solution and nano-alumina particles are loaded on the surface to achieve composite modification of the luffa and introduce double bonds to obtain an Al2O3-luffa composite material; the step (1) specifically comprises adding the luffa pretreated with alkali solution, itaconic acid and p-toluenesulfonic acid to a dimethyl sulfoxide solution, performing a carboxyl modification reaction for a period of time, then adding alumina nanoparticles, and continuing to stir the reaction, wherein the ratio of the luffa pretreated with alkali solution, itaconic acid and alumina nanoparticles is 1g: (2-4)g: (0.3-0.7)g; (2) Through the double bond cross-linking grafting of poly (4-vinylpyridine) on the Al2O3-loofah composite material, the cross-linking modification and functional modification of the loofah were achieved simultaneously.

2. The chemical modification method for improving the heavy metal adsorption performance of loofah according to claim 1, wherein The carboxyl modification reaction in step (1) is carried out by stirring at 50-80° C. for 3-6 hours.

3. The chemical modification method for improving the heavy metal adsorption performance of loofah according to claim 1, wherein After adding the aluminum oxide nanoparticles in step (1), the mixture is stirred and reacted at 50-80° C. for 3-6 hours.

4. The chemical modification method for improving the heavy metal adsorption performance of loofah according to claim 1, wherein The step (2) specifically comprises immersing the Al2O3-loofah composite material in a solution containing 4-vinylpyridine monomer. N , N -dimethylformamide solution, and then add initiator azobisisobutyronitrile under protective atmosphere to carry out cross-linking polymerization reaction.

5. The chemical modification method for improving the heavy metal adsorption performance of loofah according to claim 4, is characterized in that, The mass ratio of the Al2O3-loofah composite material to the 4-vinylpyridine monomer is 1:(0.5-2).

6. The chemical modification method for improving the heavy metal adsorption performance of loofah according to claim 4, characterized in that, The 4-vinylpyridine monomer is dissolved N , N -The concentration of dimethylformamide solution is 10~60g / L.

7. The chemical modification method for improving the heavy metal adsorption performance of loofah according to claim 4, characterized in that, The mass ratio of the 4-vinylpyridine monomer to the initiator azobisisobutyronitrile is (30-100):

1.

8. The chemical modification method for improving the heavy metal adsorption performance of loofah according to claim 4, characterized in that, The cross-linking polymerization reaction in step (2) is carried out at 50-100° C. for 10-30 hours, and after the reaction, the modified loofah is treated with N , N -Dimethylformamide, deionized water, and repeated washing and drying.

9. The chemical modification method for improving the heavy metal adsorption performance of loofah according to claim 1, wherein The alkaline solution pretreatment is to soak the loofah in a 2% to 15% NaOH aqueous solution, stir and treat it at 60 to 100° C. for 1 to 5 hours, and then wash it with deionized water until it is neutral.

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