Chitosan-stabilized magnetic loofah biochar composite adsorption material and its preparation method and application

Abstract

The present invention belongs to the technical field of adsorption materials and discloses a chitosan-stabilized magnetic loofah biochar composite adsorption material, a preparation method, and an application thereof. The preparation method comprises: removing the skin and shell of the loofah, and sequentially washing, drying, crushing, and sieving the interior to obtain loofah powder; mixing and modifying the loofah powder with a nitric acid aqueous solution, and sequentially filtering, washing to neutrality, drying, crushing, sieving, and high-temperature anaerobic pyrolysis to obtain loofah biochar; and uniformly mixing chitosan, an acetic acid aqueous solution, a magnetic raw material, and the loofah biochar, washing to remove impurities, vacuum drying, and sieving to obtain a chitosan-stabilized magnetic loofah biochar composite adsorption material. The adsorption material prepared by the present invention uses waste loofah as raw material, can achieve high-value utilization of waste agricultural and sideline resources, and is a low-cost, effective, and easily recyclable adsorption material for removing chromium from water.

Description

Technical Field

[0001] The present invention belongs to the technical field of adsorption materials, and more specifically, relates to a chitosan-stabilized magnetic loofah biochar composite adsorption material, a preparation method and an application thereof. Background Art

[0002] Chromium is widely used in metal surface treatment, electroplating, leather tanning, and other fields. However, these industries generate large amounts of chromium-containing wastewater during production, particularly hexavalent chromium wastewater. If discharged untreated, this wastewater poses a serious environmental risk. Chromium is highly toxic, and long-term exposure to chromium-containing environments can cause various diseases, such as lung cancer, skin ulcers, and genetic mutations. Therefore, the management of chromium wastewater is of paramount importance.

[0003] Adsorption is a widely used and effective method for wastewater treatment. Using specific adsorbent materials, the adsorption method purifies wastewater through the interaction between the adsorbent and ions in the wastewater. Furthermore, adsorption meets the needs of large-scale and continuous wastewater treatment, offering high practical value.

[0004] As an agricultural and sideline resource, loofah has good natural adsorption properties due to its rich cellulose and porous structure. However, a large amount of discarded loofah agricultural and sideline resources have not been effectively utilized, causing pollution problems.

[0005] Therefore, it is urgent to propose a chitosan-stabilized magnetic loofah biochar composite adsorption material and a preparation method and application thereof. Summary of the Invention

[0006] The present invention addresses the shortcomings of existing technologies and proposes a chitosan-stabilized magnetic loofah biochar composite adsorption material, its preparation method, and its application. The adsorption material prepared by the present invention uses discarded loofah as raw material, enabling high-value utilization of waste agricultural and sideline resources. It is a low-cost, highly effective, and easily recyclable adsorption material for removing chromium from water.

[0007] In order to achieve the above object, the first aspect of the present invention provides a method for preparing a chitosan-stabilized magnetic loofah biochar composite adsorption material, the preparation method comprising the following steps:

[0008] S1: removing the skin and shell of a loofah, washing, drying, crushing, and sieving the interior thereof in sequence to obtain loofah powder; mixing and modifying the loofah powder with a nitric acid aqueous solution, and filtering, washing to neutrality, drying, crushing, sieving, and pyrolyzing at high temperature and without oxygen to obtain loofah biochar;

[0009] S2: mixing chitosan, acetic acid aqueous solution, magnetic raw material and the luffa sponge biochar uniformly, washing to remove impurities, vacuum drying and sieving to obtain the chitosan-stabilized magnetic luffa sponge biochar composite adsorption material.

[0010] In the present invention, loofah sponge is converted into biochar through carbonization and activation, retaining the adsorption advantages of its original structure and giving it a larger specific surface area, thereby improving its adsorption performance. Furthermore, by adding magnetic raw materials, the movement and positioning of the loofah sponge biochar can be controlled by magnetic fields, resulting in an adsorption material that is easier to recycle and reuse.

[0011] According to the present invention, preferably, the volume of the nitric acid aqueous solution is 150-250 mL, and the mass concentration of the nitric acid aqueous solution is 20%-30%.

[0012] According to the present invention, preferably, the mixing and modification of the loofah powder and the nitric acid aqueous solution is carried out in a water bath, the temperature of the water bath is 60-90° C., and the mixing and modification time is 4-8 hours.

[0013] According to the present invention, preferably, the filtration temperature is 60-90° C. That is, after the loofah powder is mixed and modified with the nitric acid aqueous solution, the filtration is performed while the mixture is hot.

[0014] According to the present invention, preferably, the temperature of the high-temperature oxygen-free pyrolysis is 450-550° C., and the time is 1.5-2.5 hours.

[0015] According to the present invention, preferably, the volume of the acetic acid aqueous solution is 45-55 mL, and the mass concentration of the acetic acid aqueous solution is 1.5%-2.5%.

[0016] According to the present invention, preferably, the magnetic raw material is a mixture of ferrous sulfide heptahydrate and sodium sulfide aqueous solution;

[0017] The mass ratio of chitosan to ferrous sulfide heptahydrate is 1:(3-4);

[0018] The ratio of the amount of ferrous sulfide in the ferrous sulfide heptahydrate, the mass of the loofah sponge and the mass of the chitosan is (14-15) mmol: (18-22) g: (0.8-1.2) g;

[0019] The molar ratio of the sodium sulfide to the ferrous sulfide is 1:(1.4-1.5);

[0020] The molar concentration of the sodium sulfide aqueous solution is 0.15-0.25 mol / L.

[0021] According to the present invention, preferably, the screening is through an 80-120 mesh sieve.

[0022] The second aspect of the present invention provides a chitosan-stabilized magnetic loofah-biochar composite adsorption material prepared by the preparation method of the chitosan-stabilized magnetic loofah-biochar composite adsorption material.

[0023] The third aspect of the present invention provides the use of the chitosan-stabilized magnetic loofah biochar composite adsorption material as an adsorbent for chromium-containing wastewater.

[0024] The beneficial effects of the technical solution of the present invention are as follows:

[0025] The loofah sponge used in the present invention has the advantages of being biodegradable, having a large surface area, a light specific gravity, being rich in active ingredients, being readily available, low-cost, and reproducible, making it a promising environmentally friendly adsorption material. The present invention uses chitosan as a stabilizing material, which further stabilizes the adsorption performance and physical structure of the adsorption material, thereby enhancing the adsorption material's usefulness. The present invention also uses ferrous sulfide and sodium sulfide as magnetic raw materials, adding them to the adsorption material to impart magnetic properties. This allows the adsorption material to be easily separated from a solution using a magnetic field, facilitating its recycling.

[0026] The adsorption material prepared by the invention uses discarded loofah sponges as raw materials, can realize high-value utilization of discarded agricultural and sideline resources, and turn waste into treasure.

[0027] The adsorption capacity of the adsorption material prepared by the present invention for chromium is as high as 112.3 mg / g, which is higher than that of most chromium salt adsorbents. The removal rate of the adsorption material prepared by the present invention for hexavalent chromium under acidic conditions can reach up to 84%.

[0028] The adsorption material prepared by the invention is magnetized by ferrous sulfide and sodium sulfide, so that the product of the invention has higher recycling value.

[0029] The adsorption material of the invention is a low-cost, high-effect and easily recyclable adsorption material for removing chromium in water.

[0030] Other features and advantages of the present invention will be described in detail in the following detailed description. DETAILED DESCRIPTION

[0031] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. Instead, these embodiments are provided to make the present invention more thorough and complete and to fully convey the scope of the present invention to those skilled in the art.

[0032] Example 1

[0033] This embodiment provides a method for preparing a chitosan-stabilized magnetic loofah biochar composite adsorption material, the preparation method comprising the following steps:

[0034] S1: removing the skin and shell of a loofah, washing, drying, crushing, and passing through a 100-mesh sieve in sequence to obtain a loofah powder; mixing the loofah powder with 200 mL of a 20% nitric acid aqueous solution in a 90° C. water bath for 8 h, filtering while hot, washing with deionized water until neutral, drying to constant weight, crushing, passing through a 100-mesh sieve, and pyrolyzing in a tube furnace at 500° C. for 2 h in the absence of oxygen to obtain a loofah biochar;

[0035] S2: Chitosan, acetic acid aqueous solution (50 mL, 2%), ferrous sulfide heptahydrate, sodium sulfide aqueous solution and the luffa biochar were mixed and stirred evenly, impurities were washed with deionized water, vacuum dried and passed through a 100-mesh sieve to obtain the chitosan-stabilized magnetic luffa biochar composite adsorption material.

[0036] Wherein: the mass ratio of chitosan to ferrous sulfide heptahydrate is 1:3.16;

[0037] The ratio of the amount of ferrous sulfide in the ferrous sulfide heptahydrate, the mass of the loofah, and the mass of the chitosan is 14.8 mmol:20 g:1 g;

[0038] The molar ratio of the sodium sulfide to the ferrous sulfide is 1:1.48;

[0039] The molar concentration of the sodium sulfide aqueous solution is 0.2 mol / L.

[0040] Example 2

[0041] This embodiment provides a method for preparing a chitosan-stabilized magnetic loofah biochar composite adsorption material. The difference between this embodiment and Example 1 is that:

[0042] In step S1, the loofah powder is mixed with 200 mL of a 30% nitric acid aqueous solution in a 60° C. water bath for 4 h;

[0043] Step S2 is the same as that of Example 1.

[0044] Example 3

[0045] This embodiment provides a method for preparing a chitosan-stabilized magnetic loofah biochar composite adsorption material. The difference between this embodiment and Example 1 is that:

[0046] In step S1, the loofah powder is mixed with 200 mL of a 25% nitric acid aqueous solution in an 80° C. water bath for 6 h.

[0047] Step S2 is the same as that of Example 1.

[0048] The adsorption materials obtained in Examples 1-3 were added to three bottles of chromium-containing wastewater with the same chromium content, and the results were as follows:

[0049] The adsorption amounts of chromium ions in Example 1, Example 2 and Example 3 were 105.1 mg / g, 112.3 mg / g and 80.5 mg / g, respectively. When a magnet was placed close to the products of Examples 1-3, it was found that the products were obviously magnetic.

[0050] It can be seen from this that the product of the present invention has strong magnetic properties and chromium removal capabilities, and is easy to perform magnetic separation after adsorption.

[0051] While various embodiments of the present invention have been described above, the above description is intended to be illustrative, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. Application of chitosan stabilized magnetic loofah biochar composite adsorption material as an adsorbent for chromium-containing wastewater, characterized in that: The preparation method of the chitosan-stabilized magnetic loofah biochar composite adsorption material comprises the following steps: S1: removing the skin and shell of a loofah, washing, drying, crushing, and sieving the interior thereof in sequence to obtain loofah powder; mixing and modifying the loofah powder with a nitric acid aqueous solution, and filtering, washing to neutrality, drying, crushing, sieving, and pyrolyzing at high temperature and without oxygen to obtain loofah biochar; The temperature of the high temperature oxygen-free pyrolysis is 450-550°C; The volume of the nitric acid aqueous solution is 150-250 mL, and the mass concentration of the nitric acid aqueous solution is 20%-30%; The mixing and modification of the loofah powder and the nitric acid aqueous solution is carried out in a water bath, the temperature of the water bath is 60-90° C., and the mixing and modification time is 4-8 hours; S2: mixing chitosan, acetic acid aqueous solution, magnetic raw material and the luffa biochar uniformly, washing to remove impurities, vacuum drying and sieving to obtain the chitosan-stabilized magnetic luffa biochar composite adsorption material; The magnetic raw material is a mixture of ferrous sulfide heptahydrate and sodium sulfide aqueous solution; The ratio of the amount of ferrous sulfide in the ferrous sulfide heptahydrate, the mass of the loofah sponge, and the mass of the chitosan is (14-15) mmol: (18-22) g: (0.8-1.2) g; The mass ratio of chitosan to ferrous sulfide heptahydrate is 1:(3-4); The molar ratio of the sodium sulfide to the ferrous sulfide is 1:(1.4-1.5); The molar concentration of the sodium sulfide aqueous solution is 0.15-0.25 mol / L.

2. The use according to claim 1, wherein The filtration temperature is 60-90°C.

3. The use according to claim 1, wherein: The high-temperature anaerobic pyrolysis time is 1.5-2.5 hours.

4. The use according to claim 1, wherein The volume of the acetic acid aqueous solution is 45-55 mL, and the mass concentration of the acetic acid aqueous solution is 1.5%-2.5%.

5. The use according to any one of claims 1 to 4, wherein: The sieving is through an 80-120 mesh sieve.