CN113856654A

CN113856654A - Method for preparing dye adsorbent by using slag

Info

Publication number: CN113856654A
Application number: CN202111381233.7A
Authority: CN
Inventors: 邵艳群; 吴慧璇; 王金金; 李国勇; 陈孔发
Original assignee: Fuzhou University
Current assignee: Fuzhou University
Priority date: 2021-11-20
Filing date: 2021-11-20
Publication date: 2021-12-31

Abstract

The invention discloses a method for preparing a dye adsorbent by using slag. The method comprises the steps of firstly taking fluorine-containing silicon slag as a silicon source, taking polysaccharide polymer sodium alginate as an additive and inorganic acid as a catalyst, obtaining the silicon dioxide/sodium alginate composite aerogel with a stable structure and a stable shape through sol-gel, aging and freeze drying, and taking the silicon dioxide/sodium alginate composite aerogel as an adsorbent, so that malachite green in a water phase can be quickly and effectively adsorbed, and the purification of polluted water resources is realized.

Description

Method for preparing dye adsorbent by using slag

Technical Field

The invention belongs to the field of adsorption materials, and particularly relates to a method for preparing a dye adsorbent by using slag.

Background

Most of the solid waste generated in industrial processes is not effectively disposed and utilized, and is usually naturally exposed to be piled up or buried on a shallow surface. After long-term rain and surface runoff infiltration, various harmful substances such as heavy metals, organic matters and the like remained in the solid waste are diffused to underground water, soil and the like to damage the health of human bodies and even destroy the ecological environment. For example, slag after wet-process phosphorus processing has extremely strong acidity, contains fluorine elements and heavy metals, and can damage the surrounding environment if not utilized. However, the slag also contains a large amount of silicon as a result of its composition analysis. The fluorine and the silicon are fully utilized, so that the environment can be protected, and natural resources can be fully utilized.

Malachite green is a synthetic toxic triphenylmethane compound, is a dye and a bactericide, and is widely used as a food coloring agent, a food additive, a bactericide, an insect repellent and a biocide for aquaculture; meanwhile, the dye can be used as a basic dye for silk, wool, jute, leather, cotton, paper making, plastic and the like. The functional group-triphenylmethane is proved to have high toxicity, high residue, three-cause toxicity and other toxic and side effects.

Because malachite green is toxic and carcinogenic, the dye wastewater can be discharged after being treated. The main treatment methods are physical, chemical and biological methods. The adsorption is to utilize the material with large specific surface area and porous structure or polar group to adhere the pollutant on the adsorbent through the intermolecular interaction, wherein the adsorption method has wide application range, high adsorption efficiency and simple and easy operation. Activated carbon is the most common adsorbent material, but it is expensive to produce and has a low level of regeneration. The adsorption method mainly has the problems of low adsorption capacity, complex preparation process and higher cost. At present, reports of applying industrial solid wastes such as silicon slag and the like to the adsorption field are rare, and meanwhile, the problems of less adsorption reports and small adsorption amount of the silica-based adsorbent in the aspect of malachite green exist, so that researches on the aspect of malachite green adsorption of the silica-based adsorbent are still needed to be further explored.

Disclosure of Invention

The invention aims to provide a method for preparing a dye adsorbent by using slag. The preparation process is simple, and the prepared silicon dioxide/sodium alginate composite aerogel can be used as an adsorbent to quickly and effectively adsorb malachite green in a water phase, so that the purification of polluted water resources is realized.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for preparing a dye adsorbent using slag, comprising the steps of:

(1) preparing a sodium hydroxide solution with a certain concentration, adding 0.75-2.25 g of slag silicon dioxide, and stirring for a period of time at a constant temperature in a water bath to form a slag water solution with a modulus of 1-3.

(2) Weighing 0.15-0.4 g of sodium alginate, adding the sodium alginate into the slag water glass solution, stirring and dispersing to form a uniform mixed solution, taking hydrochloric acid as a catalyst, obtaining slag silicon dioxide gel by adopting a sol-gel method, and aging for 24 hours at room temperature.

(3) And (3) putting the slag silicon dioxide gel into a freeze dryer by adopting a freeze drying method, wherein the pre-freezing temperature is-70 ℃, the pre-freezing time is 12 hours, and the vacuum drying time is 24 hours to obtain the slag silicon dioxide aerogel.

Preferably, the concentration of the sodium hydroxide solution is optimally 1.5 mol/L.

Preferably, the constant temperature reaction temperature is 80 ℃, and the reaction time is 3 h.

Preferably, the adding mass of the sodium alginate is 20% of that of the fluorine-containing silicon slag.

Preferably, the modulus of the aqueous slag solution is 2.

Compared with the prior art, the invention has the beneficial effects that: the invention applies industrial solid waste to the field of adsorption for the first time, and has low cost. The preparation process is simple, and the used reagents have low price, and few types and dosage. Compared with the existing silica-based adsorbent, the adsorbent prepared by the invention has very excellent adsorption effect on the malachite green in the water phase, the adsorption capacity can reach more than 400mg/g, the adsorption kinetics is fast, the malachite green in the water phase can be quickly adsorbed in the first two hours of adsorption, and the adsorption rate can finally reach 100%.

Drawings

Fig. 1 is a macroscopic photograph of silica aerogels of example 1 and comparative example 1.

FIG. 2 is a comparison of the photomicrographs of the malachite green solution of example 1 before and after adsorption.

FIG. 3 is a graph showing the adsorption effect of the silica aerogel adsorbents of example 1 and comparative example 1 on 20ml of malachite green having a concentration of 200 mg/L.

Detailed Description

In order to make the present invention more comprehensible, the technical solutions of the present invention are further described below with reference to specific embodiments, but the present invention is not limited thereto.

Example 1

Preparing a sodium hydroxide solution with the concentration of 1.5mol/L, weighing 2.25g of fluorine-containing silicon slag and 16.7mL of the sodium hydroxide solution, uniformly mixing, placing in a constant-temperature water bath kettle at 80 ℃, and reacting for 3 hours to obtain a slag water solution with the modulus of 3. 0.038g of sodium alginate is weighed and added into the slag water glass solution, after the mixture is uniformly stirred, hydrochloric acid with the concentration of 1mol/L is used as a catalyst, the mixture is added into the slag water glass drop by drop, and when the appearance of fine white floccule is observed, the system begins to gel. And after the gel is completely gelled, aging at room temperature for 24h to enable the structure of the gel to be more stable, then pre-freezing for 12h in a pre-freezing chamber at-70 ℃, and vacuum drying for 24h to obtain the silicon dioxide/sodium alginate aerogel. Weighing 10mg of silicon dioxide/sodium alginate aerogel, putting the silicon dioxide/sodium alginate aerogel into a 20mL glass bottle containing 200mg/L of malachite green solution, setting the oscillation frequency of an oscillator to be 150r/min, and placing the glass bottle in the oscillator for oscillation for 12 hours. Experimental results show that the silicon dioxide/sodium alginate aerogel can keep a basic skeleton structure, is beneficial to recovery, and has the adsorption capacity of 400mg/g and the adsorption rate of 100%. As can be seen from fig. 3, when the silica/sodium alginate aerogel is mixed with 20ml of a malachite green solution with a concentration of 200mg/L and oscillated, the residual concentration of malachite green rapidly decreases within one hour before the oscillation, and the initial rapid adsorption effect is obtained. When the shaking time was 4 hours, the adsorption rate reached 100%.

Example 2

Preparing a sodium hydroxide solution with the concentration of 1.5mol/L, weighing 2.25g of fluorine-containing silicon slag and 16.7mL of the sodium hydroxide solution, uniformly mixing, placing in a constant-temperature water bath kettle at 80 ℃, and reacting for 3 hours to obtain a slag water solution with the modulus of 2. 0.074g of sodium alginate is weighed and added into the slag water glass solution, hydrochloric acid with the concentration of 1mol/L is used as a catalyst, and is added into the slag water glass drop by drop, and the appearance of fine white floccule is observed, and the system begins to gel. And after the gel is completely gelled, aging at room temperature for 24h to enable the structure of the gel to be more stable, then pre-freezing for 12h in a pre-freezing chamber at the temperature of-70 ℃, and performing vacuum drying for 24h to obtain the silicon dioxide aerogel. Weighing 10mg of silicon dioxide aerogel into a 20mL glass bottle containing 200mg/L of malachite green solution, setting the oscillation frequency of an oscillator to be 150r/min, and placing the glass bottle in the oscillator for oscillation for 12 h. Experimental results show that the silicon dioxide/sodium alginate aerogel can keep a basic skeleton structure and has no fine cracks. The adsorption capacity can reach more than 400mg/g, and the adsorption rate reaches 100%.

Example 3

Preparing a sodium hydroxide solution with the concentration of 1.5mol/L, weighing 2.25g of fluorine-containing silicon slag and 16.7mL of the sodium hydroxide solution, uniformly mixing, placing in a constant-temperature water bath kettle at 80 ℃, and reacting for 3 hours to obtain a slag water solution with the modulus of 2. 0.1g of sodium alginate is weighed and added into the slag water glass solution, hydrochloric acid with the concentration of 1mol/L is used as a catalyst, the sodium alginate is added into the slag water glass drop by drop, and the appearance of fine white floccule is observed, so that the system begins to gel. And after the gel is completely gelled, aging at room temperature for 24h to enable the structure of the gel to be more stable, then pre-freezing for 12h in a pre-freezing chamber at the temperature of-70 ℃, and performing vacuum drying for 24h to obtain the silicon dioxide aerogel. Weighing 10mg of silicon dioxide aerogel into a 20mL glass bottle containing 200mg/L of malachite green solution, setting the oscillation frequency of an oscillator to be 150r/min, and placing the glass bottle in the oscillator for oscillation for 12 h. Experimental results show that the silicon dioxide/sodium alginate aerogel can keep a basic skeleton structure, the adsorption capacity can reach more than 400mg/g, and the adsorption rate can reach 100%.

Comparative example 1

Preparing a sodium hydroxide solution with the concentration of 1.5mol/L, weighing 2.25g of fluorine-containing silicon slag and 16.7mL of the sodium hydroxide solution, uniformly mixing, placing in a constant-temperature water bath kettle at 80 ℃, and reacting for 3 hours to obtain a slag water solution with the modulus of 3. Hydrochloric acid with the concentration of 1mol/L is used as a catalyst, the hydrochloric acid is dropwise added into slag water glass, fine white floccules are observed to appear, and the system begins to gel. And after the gel is completely gelled, aging at room temperature for 24h to enable the structure of the gel to be more stable, then pre-freezing for 12h in a pre-freezing chamber at the temperature of-70 ℃, and performing vacuum drying for 24h to obtain the silicon dioxide aerogel. Weighing 10mg of silicon dioxide aerogel into a 20mL glass bottle containing 200mg/L of malachite green solution, setting the oscillation frequency of an oscillator to be 150r/min, and placing the glass bottle in the oscillator for oscillation for 12 h. Experimental results show that the adsorption capacity of the silicon dioxide aerogel can reach 400mg/g, and the adsorption rate can reach 100%. As can be seen from fig. 3, when the silica aerogel was mixed with 20ml of a solution of malachite green having a concentration of 200mg/L and shaken, the residual concentration of malachite green rapidly decreased within the first two hours of shaking, and there was an initial rapid adsorption effect. When the oscillation time is 6 hours, the adsorption rate is more than 95%, and the oscillation time is continuously increased to realize that the adsorption rate reaches 100%.

The above description is only a preferred embodiment of the present invention, and all equivalent changes and modifications made in accordance with the claims of the present invention should be covered by the present invention.

Claims

1. A method for preparing aerogel by utilizing slag is characterized by comprising the following steps: the silica/sodium alginate composite aerogel is prepared by taking slag as a silicon source, sodium alginate as an additive and inorganic acid as a catalyst through sol-gel, aging and freeze drying.

2. The method of claim 1, wherein: the slag is dry fluorine-containing silicon slag which is a byproduct of an anhydrous hydrogen fluoride device constructed by phosphorus ore associated fluorine resources.

3. The method of claim 1, wherein: the method comprises the following steps:

(1) adding slag into a sodium hydroxide solution, and stirring in a water bath at constant temperature to form a slag solution;

(2) adding sodium alginate into the slag solution, stirring uniformly, using hydrochloric acid as a catalyst, preparing slag silicon dioxide gel by adopting a sol-gel method, and aging at room temperature;

(3) and (5) freeze-drying to obtain the silicon dioxide/sodium alginate composite aerogel.

4. The method of claim 1, wherein: the concentration of the sodium hydroxide solution in the step (1) is 1-3 mol/L; the water bath temperature is 50-90 ℃, and the time is 2-6 h; the modulus of the slag solution is 1-3.

5. The method of claim 1, wherein: in the step (2), the mass ratio of the slag to the sodium alginate is 7.5-59.2, the pH value of a hydrochloric acid adjusting system is 9-10, and the aging time is 24 hours after gelation.

6. The method of claim 1, wherein: freeze-drying process parameters in the step (3): the pre-freezing temperature is-70 ℃ and the time is 12 hours; the vacuum drying time is 24 h.

7. A silica/sodium alginate composite aerogel prepared by the method of claim 1.

8. The application of the silicon dioxide/sodium alginate composite aerogel prepared by the method of claim 1 in dye adsorbents.