Disclosure of Invention
Aiming at the problems in the prior art, the invention provides the ion-modified red mud-based heterojunction photocatalyst as well as the preparation method and the application thereof, so that the problem of mass accumulation of solid wastes is solved, the solid wastes are changed into valuable, and the effect of recycling is achieved.
The invention is realized by the following technical scheme:
a preparation method of an ion-modified red mud-based heterojunction photocatalyst comprises the following steps:
step 1, sequentially carrying out acid treatment and drying on red mud to obtain acid-treated red mud;
step 2, according to the formula (4-8): (4-8): (2-5) uniformly mixing the acid-activated red mud, hexadecyl trimethyl ammonium bromide and cobalt nitrate in deionized water to obtain a turbid liquid;
and 3, adding a sodium silicate solution into the turbid liquid to obtain a mixed system, then adjusting the pH value of the mixed system to 2-4 to obtain a colloidal body, freezing the colloidal body, then adopting a freeze drying technology to obtain a porous block body, and finally roasting the porous block body at the temperature of 500-800 ℃ to obtain the ion-modified red mud-based heterojunction photocatalyst.
Preferably, the red mud in the step 1 is obtained according to the following processes:
drying the untreated red mud, then sequentially grinding and sieving with a 150-mesh sieve to obtain the red mud.
Preferably, in the step 1, sulfuric acid with the concentration of 1-5mol/L is used for soaking the red mud, so that the acid treatment of the red mud is completed.
Preferably, the mass ratio of the sodium silicate added in the step 3 to the cobalt nitrate in the step 2 is (11.368-17.052): (2-5).
Preferably, step 3 uses 1mol/L hydrochloric acid to adjust the pH of the mixed system.
Preferably, step 3 freeze-dries the gel after freezing for 5-8 h.
Preferably, step 3, adding a sodium silicate solution into the turbid solution, and stirring for 2-4h to obtain a mixed system.
Preferably, step 3 fires the porous block at said temperature for 5-7 hours.
An ion-modified red mud-based heterojunction photocatalyst obtained by the preparation method of the ion-modified red mud-based heterojunction photocatalyst.
The application of the ion-modified red mud-based heterojunction photocatalyst in the degradation of methylene blue.
Compared with the prior art, the invention has the following beneficial technical effects:
the invention relates to a preparation method of an ion-modified red mud-based heterojunction photocatalyst, which comprises the steps of firstly carrying out acid treatment on red mud to enable Fe in the red mud2O3The content of the cobalt nitrate is increased, the content of other alkaline oxides is reduced, a certain amount of red mud is treated by utilizing hexadecyl trimethyl ammonium bromide to activate the surface of the red mud, so that the cobalt nitrate can be uniformly mixed with a certain amount of red mud to obtain turbid liquid, then sodium silicate solution is added, and a colloid body can be formed by adjusting the pH of the mixed system to be strong acid, wherein Fe (OH) in the colloid body3The surface of the material is loaded with a large amount of cobalt nitrate, the cobalt nitrate is frozen at low temperature, the freezing and drying technology is further adopted to sublimate the solidified moisture in the material to obtain a block body with a porous structure, and the block body is roasted to form Fe2O3And Co3O4The heterojunction structure of (1). Fe2O3/Co3O4The heterojunction can degrade methylene blue. Solves the problem of mass accumulation of the solid waste red mud, changes the solid waste red mud into valuable, and realizes the resource utilization of the solid waste red mud.
Fe of the invention2O3/Co3O4The heterojunction can perform sufficient light absorption when degrading methylene blue, so as to generate more photo-generated electrons and holes, and the methylene blue can be degraded by more than 90%. The invention can achieve the purpose of treating wastes with wastes by utilizing solid wastes such as red mud.
The specific implementation mode is as follows:
the present invention will now be described in further detail with reference to specific examples, which are intended to be illustrative, but not limiting, of the invention.
The invention relates to a preparation method of an ion-modified red mud-based heterojunction photocatalyst, which comprises the following steps:
the method comprises the following steps: drying the red mud in an oven at 60-80 ℃ for 24-48 hours, grinding, sieving with a 150-mesh sieve, then acidifying in 5-15mL of 1-5mol/L sulfuric acid solution, and drying to obtain the acid-activated red mud. After acidification, Fe in red mud2O3The content of (b) is increased and the content of other basic oxides is decreased.
Step two: 4-8g of cetyltrimethylammonium bromide was dissolved in 100-300 mL of deionized water to give solution A.
Step three: then 2-5g of cobalt nitrate is dissolved in the solution A, and the solution B is obtained after stirring for 20 min.
Step four: and then adding 4-8g of acid activated red mud into the solution B, and then uniformly stirring for 20min generally to form a turbid solution C, so that cobalt nitrate and the red mud can be uniformly mixed and stirred.
Step five: then adding 20mL of sodium silicate solution with the concentration of 2-4mol/L into the turbid liquid C, stirring for 2-4 hours, adjusting the pH to 2-4 by using 1mol/L hydrochloric acid to form colloid, wherein Fe (OH) is contained in the colloid3The surface of (a) is loaded with a large amount of cobalt nitrate. It was then transferred to a freezer for 6 hours.
Step six: then the frozen colloid is put into a freeze drying box for freeze drying for 5 to 8 hours. When the material is dried, water on the surface of the material can be separated from the gaps to form a porous structure.
Step seven: then the formed porous material is put into a muffle furnace to be baked at the temperature of 500-800 DEG CAnd firing for 5-7 hours to finally form the red mud-based heterojunction photocatalytic material. Will increase the Fe of the material after acidification2O3The amount of other basic oxides decreases and Fe is formed after firing in a muffle furnace2O3/Co3O4A heterojunction structure.
The steps for degrading the methylene blue solution are as follows:
adding 100mL of methylene blue solution with the concentration of 0.04g/L into a test tube, then adding 0.4g of the material into the test tube for adsorption, carrying out a dark reaction adsorption experiment for 30min, then carrying out a reaction process in a light reaction stage, carrying out photocatalytic degradation by using a 300W xenon lamp as a light source, sampling for 3mL every 30min, centrifuging the sampled sample, testing by using ultraviolet-visible spectrophotometry, and calculating the photocatalytic degradation condition of the material according to the obtained curve.
Example 1:
the invention relates to a preparation method of an ion-modified red mud-based heterojunction photocatalyst, which comprises the following steps:
the method comprises the following steps: drying the red mud in an oven at 60 ℃ for 24 hours, grinding, sieving by a 150-mesh sieve, then acidifying in 5mL of sulfuric acid solution with the concentration of 1mol/L, and drying to obtain the acid-activated red mud. The material after acidification can lead Fe in the red mud2O3The content of (b) is increased and the content of other basic oxides is decreased.
Step two: 4g of cetyltrimethylammonium bromide was dissolved in 100mL of deionized water to obtain solution A.
Step three: then, 2g of cobalt nitrate was dissolved in the solution A, and the solution B was obtained by stirring for 20 min.
Step four: and then adding 4g of acid activated red mud into the solution B, and then uniformly stirring for 20min to form a turbid solution C, so that the cobalt nitrate and the red mud can be uniformly mixed and stirred.
Step five: then, 20mL of a 3mol/L sodium silicate solution was added to the turbid solution C, followed by stirring for 2 hoursAdjusting the pH to 2 with 1mol/L hydrochloric acid to form a colloid, Fe (OH)3The surface of (a) is loaded with a large amount of cobalt nitrate. It was then transferred to a freezer for 6 hours.
Step six: the frozen gel was then dried in a freeze drying oven for 6 hours. Water on the surface of the material separates from the gaps during drying, forming a porous structure.
Step seven: and then placing the formed porous material into a muffle furnace to be roasted for 5 hours at 500 ℃, and finally forming the red mud-based heterojunction photocatalytic material. Will increase the Fe of the material after acidification2O3The amount of other basic oxides decreases and a heterojunction structure is formed after firing in a muffle furnace.
It can be seen from FIG. 2 that the resulting material contains a large amount of Fe2O3And Co3O4In which a small amount of basic oxide is present, the resulting structure is hardly affected.
As can be seen in fig. 3, the material appears red overall.
The steps for degrading the methylene blue solution are as follows:
adding 100mL of methylene blue solution with the concentration of 0.04g/L into a test tube, then adding 0.4g of the material into the test tube for adsorption, carrying out a dark reaction adsorption experiment for 30min, then carrying out a reaction process in a light reaction stage, carrying out photocatalytic degradation by using a 300W xenon lamp as a light source, sampling for 3mL every 30min, centrifuging the sampled sample, testing by using ultraviolet-visible spectrophotometry, and calculating the photocatalytic degradation condition of the material according to the obtained curve. The calculated degradation rate of methylene blue of the material was 90%, and it can be seen in particular from fig. 1 that after degradation after two and a half hours, it can be found that the methylene blue is almost completely degraded.
Example 2:
the invention relates to a preparation method of an ion-modified red mud-based heterojunction photocatalyst, which comprises the following steps:
the method comprises the following steps: drying the red mud in an oven at 60 ℃ for 24 hours, grinding, sieving by a 150-mesh sieve, then acidifying in 5mL of sulfuric acid solution with the concentration of 2mol/L, and drying to obtain the acid-activated red mud. The material after acidification can lead Fe in the red mud2O3The content of (b) is increased and the content of other basic oxides is decreased.
Step two: 4g of cetyltrimethylammonium bromide was dissolved in 150mL of deionized water to obtain solution A.
Step three: then, 3g of cobalt nitrate was dissolved in the solution A, and the solution B was obtained by stirring for 20 min.
Step four: and then adding 5g of acid activated red mud into the solution B, and then uniformly stirring for 20min to form a turbid solution C, so that the cobalt nitrate and the red mud can be uniformly mixed and stirred.
Step five: then, 20mL of a 3mol/L sodium silicate solution was added to the turbid liquid C, followed by stirring for 2 hours, adjusting the pH to 4 with 1mol/L hydrochloric acid to form a gelatinous body, Fe (OH)3The surface of (a) is loaded with a large amount of cobalt nitrate. It was then transferred to a freezer for 6 hours.
Step six: the frozen gel was then dried in a freeze drying oven for 6 hours. Water on the surface of the material separates from the gaps during drying, forming a porous structure.
Step seven: and then placing the formed porous material into a muffle furnace to be roasted for 5 hours at the temperature of 550 ℃, and finally forming the red mud-based heterojunction photocatalytic material. Will increase the Fe of the material after acidification2O3The amount of other basic oxides decreases and a heterojunction structure is formed after firing in a muffle furnace.
The steps for degrading the methylene blue solution are as follows:
adding 100mL of methylene blue solution with the concentration of 0.04g/L into a test tube, then adding 0.4g of the material into the test tube for adsorption, carrying out a dark reaction adsorption experiment for 30min, then carrying out a reaction process in a light reaction stage, carrying out photocatalytic degradation by using a 300W xenon lamp as a light source, sampling for 3mL every 30min, centrifuging the sampled sample, testing by using ultraviolet-visible spectrophotometry, and calculating the photocatalytic degradation condition of the material according to the obtained curve. The degradation rate of methylene blue was calculated to be 92%.
Example 3:
the invention relates to a preparation method of an ion-modified red mud-based heterojunction photocatalyst, which comprises the following steps:
the method comprises the following steps: drying the red mud in an oven at 60 ℃ for 48 hours, grinding, sieving with a 150-mesh sieve, acidifying in 5mL of 3mol/L sulfuric acid solution, and drying to obtain the acid-activated red mud. The material after acidification can lead Fe in the red mud2O3The content of (b) is increased and the content of other basic oxides is decreased.
Step two: 6g of cetyltrimethylammonium bromide was dissolved in 100mL of deionized water to obtain solution A.
Step three: then, 5g of cobalt nitrate was dissolved in the solution A, and the solution B was obtained by stirring for 20 min.
Step four: then 6g of acid activated red mud is added into the solution B, and then the solution B is uniformly stirred for 20min to form a turbid solution C, so that cobalt nitrate and the red mud can be uniformly mixed and stirred.
Step five: then, 20mL of a 4mol/L sodium silicate solution was added to the turbid liquid C, followed by stirring for 3 hours, adjusting the pH to 3 with 1mol/L hydrochloric acid to form a gelatinous body, Fe (OH)3The surface of (a) is loaded with a large amount of cobalt nitrate. It was then transferred to a freezer for 6 hours.
Step six: the frozen gel was then dried in a freeze drying oven for 5 hours. Water on the surface of the material separates from the gaps during drying, forming a porous structure.
Step seven: and then placing the formed porous material into a muffle furnace to be roasted for 5 hours at the temperature of 600 ℃, and finally forming the red mud-based heterojunction photocatalytic material. Will increase the Fe of the material after acidification2O3The amount of other basic oxides decreases and a heterojunction structure is formed after firing in a muffle furnace.
The steps for degrading the methylene blue solution are as follows:
adding 100mL of methylene blue solution with the concentration of 0.04g/L into a test tube, then adding 0.4g of the material into the test tube for adsorption, carrying out a dark reaction adsorption experiment for 30min, then carrying out a reaction process in a light reaction stage, carrying out photocatalytic degradation by using a 300W xenon lamp as a light source, sampling for 3mL every 30min, centrifuging the sampled sample, testing by using ultraviolet-visible spectrophotometry, and calculating the photocatalytic degradation condition of the material according to the obtained curve. The degradation rate of methylene blue was calculated to be 85%.
Example 4:
the invention relates to a preparation method of an ion-modified red mud-based heterojunction photocatalyst, which comprises the following steps:
the method comprises the following steps: drying the red mud in an oven at 60 ℃ for 48 hours, grinding, sieving with a 150-mesh sieve, acidifying in 10mL of 3mol/L sulfuric acid solution, and drying to obtain the acid-activated red mud. The material after acidification can lead Fe in the red mud2O3The content of (b) is increased and the content of other basic oxides is decreased.
Step two: 6g of cetyltrimethylammonium bromide was dissolved in 150mL of deionized water to obtain solution A.
Step three: then, 5g of cobalt nitrate was dissolved in the solution A, and the solution B was obtained by stirring for 20 min.
Step four: then 6g of acid activated red mud is added into the solution B, and then the solution B is uniformly stirred for 20min to form a turbid solution C, so that cobalt nitrate and the red mud can be uniformly mixed and stirred.
Step five: then, 20mL of a 3mol/L sodium silicate solution was added to the turbid liquid C, followed by stirring for 3 hours, adjusting the pH to 2 with 1mol/L hydrochloric acid to form a gelatinous body, Fe (OH)3The surface of (a) is loaded with a large amount of cobalt nitrate. Then transfer itFreezing for 6 hours in a freezer.
Step six: the frozen gel was then dried in a freeze drying oven for 8 hours. Water on the surface of the material separates from the gaps during drying, forming a porous structure.
Step seven: and then placing the formed porous material into a muffle furnace to be roasted for 5 hours at 650 ℃, and finally forming the red mud-based heterojunction photocatalytic material. Will increase the Fe of the material after acidification2O3The amount of other basic oxides decreases and a heterojunction structure is formed after firing in a muffle furnace.
The steps for degrading the methylene blue solution are as follows:
adding 100mL of methylene blue solution with the concentration of 0.04g/L into a test tube, then adding 0.4g of the material into the test tube for adsorption, carrying out a dark reaction adsorption experiment for 30min, then carrying out a reaction process in a light reaction stage, carrying out photocatalytic degradation by using a 300W xenon lamp as a light source, sampling for 3mL every 30min, centrifuging the sampled sample, testing by using ultraviolet-visible spectrophotometry, and calculating the photocatalytic degradation condition of the material according to the obtained curve. The degradation rate of methylene blue was calculated to be 80%.
Example 5:
the invention relates to a preparation method of an ion-modified red mud-based heterojunction photocatalyst, which comprises the following steps:
the method comprises the following steps: drying the red mud in an oven at 70 ℃ for 24 hours, grinding, sieving by a 150-mesh sieve, then acidifying in 10mL of sulfuric acid solution with the concentration of 4mol/L, and drying to obtain the acid-activated red mud. The material after acidification can lead Fe in the red mud2O3The content of (b) is increased and the content of other basic oxides is decreased.
Step two: 6g of cetyltrimethylammonium bromide was dissolved in 200mL of deionized water to obtain solution A.
Step three: then 4g of cobalt nitrate was dissolved in the solution A, and the solution B was obtained by stirring for 20 min.
Step four: then 8g of acid activated red mud is added into the solution B, and then the solution B is uniformly stirred for 20min to form a turbid solution C, so that cobalt nitrate and the red mud can be uniformly mixed and stirred.
Step five: then, 20mL of a 4mol/L sodium silicate solution was added to the turbid liquid C, followed by stirring for 2 hours, adjusting the pH to 4 with 1mol/L hydrochloric acid to form a gelatinous body, Fe (OH)3The surface of (a) is loaded with a large amount of cobalt nitrate. It was then transferred to a freezer for 6 hours.
Step six: the frozen gel was then dried in a freeze drying oven for 7 hours. Water on the surface of the material separates from the gaps during drying, forming a porous structure.
Step seven: and then placing the formed porous material into a muffle furnace to be roasted for 6 hours at 700 ℃, and finally forming the red mud-based heterojunction photocatalytic material. Will increase the Fe of the material after acidification2O3The amount of other basic oxides decreases and a heterojunction structure is formed after firing in a muffle furnace.
The steps for degrading the methylene blue solution are as follows:
adding 100mL of methylene blue solution with the concentration of 0.04g/L into a test tube, then adding 0.4g of the material into the test tube for adsorption, carrying out a dark reaction adsorption experiment for 30min, then carrying out a reaction process in a light reaction stage, carrying out photocatalytic degradation by using a 300W xenon lamp as a light source, sampling for 3mL every 30min, centrifuging the sampled sample, testing by using ultraviolet-visible spectrophotometry, and calculating the photocatalytic degradation condition of the material according to the obtained curve. The degradation rate of methylene blue was calculated to be 86%.
Example 6:
the invention relates to a preparation method of an ion-modified red mud-based heterojunction photocatalyst, which comprises the following steps:
the method comprises the following steps: drying red mud in an oven at 70 ℃ for 48 hours, grinding, sieving with a 150-mesh sieve, and concentrating in 15mLAcidifying in a sulfuric acid solution with the degree of 5mol/L, and drying to obtain the acid-activated red mud. The material after acidification can lead Fe in the red mud2O3The content of (b) is increased and the content of other basic oxides is decreased.
Step two: 8g of cetyltrimethylammonium bromide was dissolved in 250mL of deionized water to obtain solution A.
Step three: then, 5g of cobalt nitrate was dissolved in the solution A, and the solution B was obtained by stirring for 20 min.
Step four: and then adding 7g of acid activated red mud into the solution B, and then uniformly stirring for 20min generally to form a turbid solution C, so that the cobalt nitrate and the red mud can be uniformly mixed and stirred.
Step five: then, 20mL of a 4mol/L sodium silicate solution was added to the turbid liquid C, followed by stirring for 4 hours, adjusting the pH to 3 with 1mol/L hydrochloric acid to form a gelatinous body, Fe (OH)3The surface of (a) is loaded with a large amount of cobalt nitrate. It was then transferred to a freezer for 6 hours.
Step six: the frozen gel was then dried in a freeze drying oven for 7 hours. Water on the surface of the material separates from the gaps during drying, forming a porous structure.
Step seven: and then placing the formed porous material into a muffle furnace to be roasted for 5 hours at 800 ℃, and finally forming the red mud-based heterojunction photocatalytic material. Will increase the Fe of the material after acidification2O3The amount of other basic oxides decreases and a heterojunction structure is formed after firing in a muffle furnace.
The steps for degrading the methylene blue solution are as follows:
adding 100mL of methylene blue solution with the concentration of 0.04g/L into a test tube, then adding 0.4g of the material into the test tube for adsorption, carrying out a dark reaction adsorption experiment for 30min, then carrying out a reaction process in a light reaction stage, carrying out photocatalytic degradation by using a 300W xenon lamp as a light source, sampling for 3mL every 30min, centrifuging the sampled sample, testing by using ultraviolet-visible spectrophotometry, and calculating the photocatalytic degradation condition of the material according to the obtained curve. The degradation rate of methylene blue was calculated to be 76%.
Example 7:
the invention relates to a preparation method of an ion-modified red mud-based heterojunction photocatalyst, which comprises the following steps:
the method comprises the following steps: drying the red mud in an oven at 80 ℃ for 48 hours, grinding, sieving by a 150-mesh sieve, then acidifying in 5mL of sulfuric acid solution with the concentration of 3mol/L, and drying to obtain the acid-activated red mud. The material after acidification can lead Fe in the red mud2O3The content of (b) is increased and the content of other basic oxides is decreased.
Step two: 4g of cetyltrimethylammonium bromide was dissolved in 300mL of deionized water to obtain solution A.
Step three: then, 5g of cobalt nitrate was dissolved in the solution A, and the solution B was obtained by stirring for 20 min.
Step four: then 8g of acid activated red mud is added into the solution B, and then the solution B is uniformly stirred for 20min to form a turbid solution C, so that cobalt nitrate and the red mud can be uniformly mixed and stirred.
Step five: then, 20mL of a 3mol/L sodium silicate solution was added to the turbid liquid C, followed by stirring for 2 hours, adjusting the pH to 2 with 1mol/L hydrochloric acid to form a gelatinous body, Fe (OH)3The surface of (a) is loaded with a large amount of cobalt nitrate. It was then transferred to a freezer for 6 hours.
Step six: the frozen gel was then dried in a freeze drying oven for 6 hours. Water on the surface of the material separates from the gaps during drying, forming a porous structure.
Step seven: and then placing the formed porous material into a muffle furnace to be roasted for 7 hours at the temperature of 550 ℃, and finally forming the red mud-based heterojunction photocatalytic material. Will increase the Fe of the material after acidification2O3The amount of other basic oxides decreases and a heterojunction structure is formed after firing in a muffle furnace.
The steps for degrading the methylene blue solution are as follows:
adding 100mL of methylene blue solution with the concentration of 0.04g/L into a test tube, then adding 0.4g of the material into the test tube for adsorption, carrying out a dark reaction adsorption experiment for 30min, then carrying out a reaction process in a light reaction stage, carrying out photocatalytic degradation by using a 300W xenon lamp as a light source, sampling for 3mL every 30min, centrifuging the sampled sample, testing by using ultraviolet-visible spectrophotometry, and calculating the photocatalytic degradation condition of the material according to the obtained curve. The degradation rate of methylene blue was calculated to be 78%.