Rapid preparation method and application of water-absorbing sponge loaded ultrathin single-layer iron-zinc-aluminum ternary hydrotalcite

Abstract

The invention belongs to the technical field of aqueous solutions and soil remediation, and discloses a rapid preparation method and application of water-absorbing sponge loaded ultrathin single-layer iron-zinc-aluminum ternary hydrotalcite, and the rapid preparation method comprises the following steps: soaking low-density sponge in a first mixed solution containing FeCl2. 4H2O, ZnCl2 and AlCl3. 6H2O, and stirring for 20-30 minutes; the preparation method comprises the following steps: adding iron-zinc-aluminum ternary hydrotalcite into sponge, sealing and stirring, adding a mixed solution containing polyvinylpyrrolidone and butane-1, 4-bis (dodecyldimethylammonium bromide) into the sponge, regulating the pH value of the system to 9-12 by using a NaOH solution, and then transferring the system into a microwave reaction kettle to react, so that iron-zinc-aluminum ternary hydrotalcite nanoparticles uniformly grow on the sponge; and after the reaction is finished, cooling the reaction liquid to room temperature, centrifugally washing the obtained composite material, drying in a vacuum drying oven, and grinding to obtain the water-absorbing sponge loaded ultrathin single-layer iron-zinc-aluminum ternary hydrotalcite composite material. The invention has the advantages of simple preparation and low cost, and can be widely applied to aqueous solution and soil remediation.

Description

Technical Field

[0001] The present invention belongs to the technical fields of aqueous solutions and soil remediation, and particularly relates to a rapid preparation method and application of a superabsorbent sponge loaded with ultrathin single-layer iron-zinc-aluminum ternary hydrotalcite. Background Art

[0002] Chromium is a relatively scarce but ubiquitous element. Due to natural weathering and ocean current movements, and more importantly, human activities (metallurgy, mining, electroplating, etc.), the content of chromium has been continuously accumulating. It usually exists in the form of hexavalent chromate and trivalent chromite in the natural environment. These two forms have different toxicological characteristics, bioavailability, and migration and transformation capabilities. Cr(III) has relatively low toxicity and forms precipitates with extremely low solubility when adsorbed, while Cr(VI) exhibits high solubility and strong oxidizing properties and is very active. More importantly, Cr(VI) has teratogenic and mutagenic characteristics, can be absorbed by crops and endanger human health through the food chain, while Cr(III) is an essential trace element for human and animal health (regulating lipid and sugar metabolism). Therefore, it is necessary to develop improved adsorbent materials with high adsorption performance, easy recyclability, and potential for reuse.

[0003] Layered double metal hydroxides (abbreviated as LDHs), also known as anionic clays or hydrotalcites, are two-dimensional layered nanomaterials. The controllability of the LDHs layer board enables them to exhibit different properties when combined with different metal cations, and the exchangeability of the interlayer anions endows them with a large anion adsorption capacity and specific functions. In recent years, due to the characteristics of low cost and high removal efficiency of LDHs, they have been widely used in the removal of pollutants. For example, the MgAL-LDH synthesized by Zhang et al. efficiently removed Cr(VI) through the exchangeability of interlayer anions. Alidokht et al. found through column experiments that FeAl-LDH removed Cr(VI) through the exchangeability of interlayer anions and Fe 2+Strong reducibility significantly reduces the concentration of leachable Cr(VI) in soil. Since China has rich iron ore reserves, the raw materials for the preparation of iron-zinc-aluminum ternary hydrotalcite are relatively abundant. More importantly, iron is an essential micronutrient that controls biological metabolism and growth. The rhizosphere activities of many plants are related to iron, regulating the natural fertility of the soil. Fortunately, due to the anisotropy of two-dimensional nanosheets, with a thickness of about one nanometer and a lateral size ranging from submicrons to dozens of microns, it allows the synthesis of LDHs as a basic building block for functional solids. In addition, the sponge can adapt to the shapes and sizes of various products, has a rich porous structure and a large specific surface area. Loading on the iron-zinc-aluminum ternary hydrotalcite is beneficial to the dispersion of the hydrotalcite, easy to recycle, and reduces the risk of secondary pollution. More importantly, the sponge can also be hybridized with nanomaterials through physical blending or chemical modification, greatly improving the adsorption performance. However, there is no report on the application of water-absorbing sponge loaded with iron-zinc-aluminum ternary hydrotalcite in the removal of Cr(VI) from aqueous solutions and soil. Therefore, it is of great significance to load a water-absorbing sponge on the iron-zinc-aluminum ternary hydrotalcite to repair chromium pollution in aqueous solutions and soil. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: aiming at the deficiencies in the prior art, to provide a water-absorbing sponge loaded with ultra-thin single-layer iron-zinc-aluminum ternary hydrotalcite composite material with high efficiency in adsorbing Cr(VI), simple operation, low cost and environmental friendliness, so as to achieve strong adsorption of heavy metal chromium ions in aqueous solution and soil systems, and then achieve the repair of aqueous solution and soil systems.

[0005] To solve the above technical problems, the technical solution adopted by the present invention is: a preparation method of a water-absorbing sponge loaded with ultra-thin single-layer iron-zinc-aluminum ternary hydrotalcite composite material, comprising the following steps:

[0006] Step 1: Immerse a water-absorbing low-density sponge in a first mixed solution containing FeCl 2 ·4H 2 O, ZnCl 2 and AlCl 3 ·6H 2 O, seal and stir until the solid dissolves, then add a second mixed solution containing polyvinylpyrrolidone and butane-1,4-bis(dodecyldimethylammonium bromide) to form a third mixed solution; after the sponge completely absorbs the third mixed solution, adjust the pH value of the system to 9-12 with NaOH solution, then quickly transfer the third mixed solution to a microwave reaction kettle, and carry out the reaction under closed conditions to make the iron-zinc-aluminum ternary hydrotalcite nanoparticles grow uniformly on the sponge;

[0007] Step 2: After the reaction is completed, wait for the reaction solution to cool to room temperature. Wash and centrifuge the obtained composite material once with a mixed solution of alcohol and water with an alcohol-water ratio of 3:7, and then wash and centrifuge it twice with an absolute ethanol solution.

[0008] Step 3: Place the product after washing and centrifuging in a vacuum drying oven for drying, and obtain a water-absorbing sponge-supported ultrathin single-layer iron-zinc-aluminum ternary hydrotalcite composite material after grinding.

[0009] In the said Step 1, the porosity of the added sponge is 85-98%, and the thickness is 5-20 mm.

[0010] In the said Step 1, in the mixed solution, the sum of FeCl 2 ·4H 2 O and ZnCl 2 and the molar ratio of AlCl 3 ·6H 2 O is 2-4:1.

[0011] In the said Step 1, the mass ratio of the sponge to AlCl 3 ·6H 2 O in the mixed solution is 1:2-5.

[0012] In the said Step 1, in the added second mixed solution, the concentrations of polyvinylpyrrolidone and butane-1,4-bis(dodecyldimethylammonium bromide) are both 0.1-0.5 wt%.

[0013] In the said Step 1, the concentration of the added NaOH solution is 1-4 mol / L.

[0014] In the said Step 1, the microwave reaction temperature is 80-120 °C, and the microwave reaction time is 10-20 min.

[0015] In the prepared composite material, the particle size of the iron-zinc-aluminum ternary hydrotalcite flakes is 50-200 nm, the thickness is 0.5-1.2 nm, and the specific surface area is 50-200 m 2 / g.

[0016] In the said Step 2, the centrifugation rate is 4000-6000 r / min, and the centrifugation time is 2-5 min.

[0017] In addition, the present invention also provides the application of the water-absorbing sponge-supported ultrathin single-layer iron-zinc-aluminum ternary hydrotalcite composite material in the treatment of chromium-polluted aqueous solutions and soil remediation. The water-absorbing sponge-supported ultrathin single-layer iron-zinc-aluminum ternary hydrotalcite composite material is obtained based on the said preparation method, and its application method is as follows:

[0018] Uniformly apply the water-absorbing sponge-supported ultrathin single-layer iron-zinc-aluminum ternary hydrotalcite composite material to the heavy metal chromium-polluted aqueous solution and soil for in-situ remediation.

[0019] Compared with the prior art, a rapid preparation method and application of a water-absorbent sponge loaded with ultrathin single-layer iron-zinc-aluminum ternary hydrotalcite provided by the present invention have the following advantages:

[0020] 1. As an adsorbent, the water-absorbent sponge loaded with ultrathin single-layer iron-zinc-aluminum ternary hydrotalcite composite material prepared by the present invention has a strong adsorption capacity for heavy metal chromium ions in aqueous solutions and soil systems, and has relatively poor migration and diffusion ability in soil, making it difficult to cause secondary pollution to the soil. At the same time, it is convenient to separate the reacted material from the soil later. It has a large specific surface area, a rich pore structure, good adsorption effect, can rapidly adsorb Cr(VI) and fix it in a short time, has a good repair effect on acidic and alkaline aqueous solutions and soil, does not release toxic substances, is easy to recycle, and does not produce secondary pollution.

[0021] 2. The preparation method of the present invention has the advantages of simple steps, low cost, and short preparation time, while the crystallization time of hydrotalcite by the traditional preparation method requires 48 to 72 hours. Therefore, the present invention has broad application prospects. Description of the Drawings

[0022] Figure 1 It is an AFM diagram of a water-absorbent sponge loaded with ultrathin single-layer iron-zinc-aluminum ternary hydrotalcite composite material obtained in Example 1 of the present invention;

[0023] Figure 2 It is an SEM diagram of a water-absorbent sponge loaded with ultrathin single-layer iron-zinc-aluminum ternary hydrotalcite composite material obtained in Example 1 of the present invention. Detailed Embodiments

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments; based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0025] Example 1

[0026] Example 1 of the present invention provides a preparation method of a water-absorbent sponge loaded with ultrathin single-layer iron-zinc-aluminum ternary hydrotalcite composite material, including the following steps:

[0027] Step 1: Soak a low-density sponge with water absorption in a solution containing FeCl 2 ·4H 2 O, ZnCl 2 and AlCl 3 ·6H2 In the first mixed solution of O, seal and stir until the solid dissolves, and then add a second mixed solution containing polyvinylpyrrolidone and butane-1,4-bis(dodecyldimethylammonium bromide) to form a third mixed solution; after the sponge completely absorbs the third mixed solution, adjust the pH value of the system to 9-12 with NaOH solution, and then quickly transfer the third mixed solution to a microwave reaction kettle and react under closed conditions to uniformly grow iron-zinc-aluminum ternary hydrotalcite nanoparticles on the sponge.

[0028] In the first step, the porosity of the added sponge is 85-98%, and the thickness is 5-20 mm. In addition, in this embodiment, the sponge is a square with a side length of 5-20 mm.

[0029] In the first step, in the mixed solution, FeCl 2 ·4H 2 O and ZnCl 2 The sum of and AlCl 3 ·6H 2 The molar ratio of O is 2-4:1.

[0030] In the first step, the mass ratio of the sponge to AlCl 3 ·6H 2 O is 1:2-5.

[0031] In the first step, in the second mixed solution containing polyvinylpyrrolidone and butane-1,4-bis(dodecyldimethylammonium bromide), the concentrations of polyvinylpyrrolidone and butane-1,4-bis(dodecyldimethylammonium bromide) are both 0.1-0.5 wt%.

[0032] In the first step, the concentration of the added NaOH solution is 1-4 mol / L.

[0033] In the first step, the microwave reaction temperature is 80-120 °C, and the microwave reaction time is 10-20 min.

[0034] Step 2: After the reaction is completed, wait for the reaction solution to cool to room temperature, wash and centrifuge the obtained composite material once with a mixed solution with an alcohol-water ratio of 3:7, and then wash and centrifuge it twice with an absolute ethanol solution.

[0035] In the second step, the centrifugation rate is 4000-6000 r / min, and the centrifugation time is 2-5 min.

[0036] Step 3: Place the product after washing and centrifugation in a vacuum drying oven and dry it at 50 °C, and then grind it to obtain a water-absorbing sponge-supported ultrathin single-layer iron-zinc-aluminum ternary hydrotalcite composite material.

[0037] Specifically, in the composite material prepared by the preparation method of this embodiment, the particle size of the iron-zinc-aluminum ternary hydrotalcite thin flakes is 50-200 nm, the thickness is 0.5-1.2 nm, and the specific surface area is 50-200 m 2 / g.

[0038] As Figures 1 - 2 shown, the AFM image and SEM image of a water-absorbent sponge loaded with an ultrathin single-layer iron-zinc-aluminum ternary hydrotalcite composite material obtained in Embodiment 1 of the present invention are shown. It can be seen from the figure that in the water-absorbent sponge loaded with the iron-zinc-aluminum ternary hydrotalcite composite material prepared in this embodiment, the iron-zinc-aluminum ternary hydrotalcite is a single-layer flake structure.

[0039] Embodiment 2

[0040] The second embodiment of the present invention provides an application of a water-absorbent sponge loaded with an ultrathin single-layer iron-zinc-aluminum ternary hydrotalcite composite material in the treatment of chromium-polluted aqueous solutions and soil remediation. The water-absorbent sponge loaded with the ultrathin single-layer iron-zinc-aluminum ternary hydrotalcite composite material is prepared based on the method described in Embodiment 1, and its application method is as follows: The water-absorbent sponge loaded with the ultrathin single-layer iron-zinc-aluminum ternary hydrotalcite composite material is uniformly applied to the heavy metal chromium-polluted aqueous solution and soil for in-situ remediation.

[0041] Experiments have confirmed that the removal efficiencies of the water-absorbent sponge loaded with the ultrathin single-layer iron-zinc-aluminum ternary hydrotalcite composite material for Cd(II), Pb(II), Cr(VI), As(V) and Hg(II) in aqueous solutions are 70.23%, 85.69%, 98.82%, 60.81% and 80.79%, respectively.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a water-absorbent sponge-loaded ultra-thin single-layer iron-zinc-aluminum ternary hydrotalcite composite material, characterized in that: The following steps are involved: Step 1: soaking a water-absorbent low-density sponge in a first mixed solution containing FeCl2·4H2O, ZnCl2 and AlCl3·6H2O, sealing and stirring until the solid is dissolved, and then adding a second mixed solution containing polyvinyl pyrrolidone and butane-1,4-bis(dodecyldimethylammonium bromide) to form a third mixed solution; after the sponge completely absorbs the third mixed solution, adjusting the pH value of the system to 9-12 with a NaOH solution, and then quickly transferring the third mixed solution to a microwave reactor, reacting under closed conditions, so that the iron-zinc-aluminum ternary hydrotalcite nanoparticles grow evenly on the sponge; Step 2: After the reaction is completed, the reaction solution is cooled to room temperature, and the obtained composite material is washed and centrifuged once with a mixed solution of alcohol and water in a ratio of 3:7, and then washed and centrifuged twice with anhydrous ethanol solution; Step 3: Dry the product after washing and centrifugation in a vacuum drying oven, and grind it to obtain a water-absorbent sponge-loaded ultra-thin single-layer iron-zinc-aluminum ternary hydrotalcite composite material.

2. The method for preparing a water-absorbent sponge-loaded ultra-thin single-layer iron-zinc-aluminum ternary hydrotalcite composite material according to claim 1, characterized in that: In the step 1, the added sponge has a porosity of 85-98% and a thickness of 5-20 mm.

3. The method for preparing a water-absorbent sponge-loaded ultra-thin single-layer iron-zinc-aluminum ternary hydrotalcite composite material according to claim 1, characterized in that: In the step 1, the molar ratio of the sum of FeCl2·4H2O and ZnCl2 to AlCl3·6H2O in the mixed solution is 2 to 4:

1.

4. The method for preparing a water-absorbent sponge-loaded ultra-thin single-layer iron-zinc-aluminum ternary hydrotalcite composite material according to claim 1, characterized in that: In the step 1, the mass ratio of the sponge to the AlCl3·6H2O in the mixed solution is 1:2-5.

5. The method for preparing a water-absorbent sponge-loaded ultra-thin single-layer iron-zinc-aluminum ternary hydrotalcite composite material according to claim 1, characterized in that: In the step 1, the concentrations of polyvinyl pyrrolidone and butane-1,4-bis(dodecyldimethylammonium bromide) in the added second mixed solution are both 0.1-0.5 wt %.

6. The method for preparing a water-absorbent sponge-loaded ultra-thin single-layer iron-zinc-aluminum ternary hydrotalcite composite material according to claim 1, characterized in that: In the step 1, the concentration of the added NaOH solution is 1-4 mol / L.

7. The method for preparing a water-absorbent sponge-loaded ultra-thin single-layer iron-zinc-aluminum ternary hydrotalcite composite material according to claim 1, characterized in that: In the step 1, the microwave reaction temperature is 80-120° C., and the microwave reaction time is 10-20 min.

8. The method for preparing a water-absorbent sponge-loaded ultra-thin single-layer iron-zinc-aluminum ternary hydrotalcite composite material according to claim 1, characterized in that: In the prepared composite material, the particle size of the Fe-Zn-Al ternary hydrotalcite flakes is 50-200nm, the thickness is 0.5-1.2nm, and the specific surface area is 50-200m 2 / g.

9. The method for preparing a water-absorbent sponge-loaded ultra-thin single-layer iron-zinc-aluminum ternary hydrotalcite composite material according to claim 1, characterized in that: In the step 2, the centrifugal speed is 4000-6000 r / min, and the centrifugal time is 2-5 min.

10. An application of an ultra-thin single-layer iron-zinc-aluminum ternary hydrotalcite composite material loaded with a water-absorbent sponge in the remediation of chromium-contaminated aqueous solutions and soils, characterized in that: The water-absorbing sponge-loaded ultra-thin single-layer iron-zinc-aluminum ternary hydrotalcite composite material is obtained based on the preparation method according to any one of claims 1 to 9, and its application method is: The water-absorbent sponge-loaded ultra-thin single-layer Fe-Zn-Al ternary hydrotalcite composite material was uniformly applied to heavy metal chromium-contaminated aqueous solution and soil for in-situ remediation.

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