Compression-resistant sterilization modified activated carbon adsorbent and preparation method thereof

Abstract

The invention relates to a compression-resistant sterilization modified activated carbon adsorbent and a preparation method thereof. The activated carbon adsorbent comprises the following components: 120-150 parts of oxidation modified sludge activated carbon; 20-30 parts of wheat straw powder; 15-20 parts of rock wool fiber; 10 to 15 parts of bamboo fiber; 2-3 parts of cerium oxide; 1-2 parts of ammonium persulfate; 70 to 80 parts of modified diatomite; 3-4 parts of lignin; 8 to 10 parts of modified attapulgite; and 10 to 20 parts of water. The preparation method comprises the following steps: preparing oxidation modified sludge activated carbon, preparing modified diatomite, preparing modified attapulgite, and preparing the activated carbon adsorbent. The activated carbon is prepared from the sludge, so that resources are saved, wastes can be utilized, the production cost of the activated carbon adsorbent is reduced, the pressure resistance and the specific surface area of the activated carbon adsorbent are increased by adding the rock wool fibers and the bamboo fibers, the porosity is improved, organic matters can be quickly decomposed by cerium oxide and ammonium persulfate, and the adsorption treatment efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of activated carbon adsorbent preparation, and more particularly to a pressure-resistant and bactericidal modified activated carbon adsorbent and its preparation method. Background Technology

[0002] Activated carbon is a porous adsorbent material with abundant pore structure, high specific surface area and strong adsorption capacity. It is widely used in air purification, deodorization, decolorization and sewage treatment, and the demand is increasing day by day.

[0003] However, the raw materials for activated carbon are mainly carbon-containing materials such as coal and wood, which are costly. The activated carbon produced has low compressive strength, low specific surface area, and low adsorption and bactericidal properties. Summary of the Invention

[0004] The present invention aims to address the shortcomings of the prior art by providing a pressure-resistant and bactericidal modified activated carbon adsorbent and its preparation method.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A pressure-resistant and bactericidal modified activated carbon adsorbent, the specific components and their weight parts are as follows:

[0007] 120-150 parts of oxidatively modified activated carbon for sludge;

[0008] 20-30 parts wheatgrass powder;

[0009] 15-20 parts rock wool fiber;

[0010] 10-15 parts bamboo fiber;

[0011] 2-3 parts of cerium oxide;

[0012] 1-2 parts of ammonium persulfate;

[0013] 70-80 parts of modified diatomaceous earth;

[0014] 3-4 parts lignin;

[0015] 8-10 parts of modified attapulgite;

[0016] 10-20 parts water.

[0017] The specific components and their weight percentages of the modified diatomaceous earth are as follows: 80-90 parts diatomaceous earth; 10-15 parts maifanite; 1-2 parts nano carbon; 1-2 parts ascorbic acid; 1-2 parts coix seed oil; 1-2 parts sodium dodecylbenzenesulfonate; 1-2 parts zinc gluconate; and 2-3 parts dandelion powder.

[0018] The specific components and their weight percentages of the modified attapulgite are as follows: attapulgite 100-120 parts; sodium carbonate 1-2 parts; alumina 2-3 parts; magnesium oxide 2-3 parts; titanium sulfate 10-12 parts; white sugar 2-3 parts; sodium lignosulfonate 2-3 parts; jade powder 10-12 parts; ammonium molybdate 1-2 parts; chromium oxide 2-3 parts; morpholine 1-2 parts; water 5-10 parts.

[0019] The preparation method of the above-mentioned pressure-resistant and bactericidal modified activated carbon adsorbent includes the following specific steps:

[0020] S1. Preparation of oxidatively modified activated carbon from sludge

[0021] Dry sludge is placed in a carbonization furnace and carbonized at 600-800℃ in a nitrogen atmosphere. The carbonized product is then placed in an oxidant solution for oxidative modification and finally dried to obtain oxidized modified sludge activated carbon.

[0022] S2, Preparation of modified diatomaceous earth

[0023] Diatomaceous earth and maifanite are calcined in a furnace at 550℃ for 3-4 hours, removed, soaked in hydrochloric acid solution for 4-5 hours, filtered, washed repeatedly with water, dried, added to water, and simultaneously added nano carbon, ascorbic acid, and zinc gluconate. The mixture is then ground to obtain a slurry, spray-dried, and then mixed with coix seed oil, sodium dodecylbenzene sulfonate, dandelion powder, and the dried powder. The mixture is then ground and dispersed to obtain modified diatomaceous earth.

[0024] S3. Preparation of modified attapulgite soil

[0025] Attapulgite clay, white sugar, sodium lignosulfonate, and sodium carbonate are mixed and kneaded into a mud-like consistency with water. The mud is then placed in a calcining furnace and calcined at 950°C for 3-4 hours. The mud is then removed and mixed with alumina, magnesium oxide, titanium sulfate, jade powder, ammonium molybdate, chromium oxide, morpholine, and water. The mixture is ground to obtain a 200-300 mesh slurry, which is then spray-dried to obtain modified attapulgite clay.

[0026] S4. Preparation of activated carbon adsorbent

[0027] Oxidized modified sludge activated carbon, wheat straw powder, rock wool fiber, bamboo fiber, cerium oxide, and lignin are added to water, heated to 80-90℃, and ground for 40-60 minutes. Then ammonium persulfate is added, stirred for 1-2 hours, and ground again to obtain a 200-300 mesh slurry. This slurry is spray-dried, mixed evenly with modified diatomaceous earth and modified attapulgite, and sent to a treatment furnace. It is then treated at 350-380℃ for 3-4 hours and removed to obtain the activated carbon adsorbent.

[0028] The oxidizing agent solution in step S1 is benzoyl peroxide solution.

[0029] The beneficial effects of this invention are as follows: This invention uses sludge to prepare activated carbon, which effectively replaces traditional materials such as charcoal and coal. This not only saves resources but also enables waste utilization and reduces the production cost of activated carbon adsorbents. The addition of rock wool fiber and bamboo fiber increases the compressive strength and specific surface area of ​​the activated carbon adsorbent, thereby improving porosity. Cerium oxide and ammonium persulfate can rapidly decompose organic matter, thereby improving adsorption treatment efficiency. Detailed Implementation

[0030] The present invention will be further described below with reference to specific embodiments:

[0031] A pressure-resistant and bactericidal modified activated carbon adsorbent, the specific components and their weight parts are as follows:

[0032] 120-150 parts of oxidatively modified activated carbon for sludge;

[0033] 20-30 parts wheatgrass powder;

[0034] 15-20 parts rock wool fiber;

[0035] 10-15 parts bamboo fiber;

[0036] 2-3 parts of cerium oxide;

[0037] 1-2 parts of ammonium persulfate;

[0038] 70-80 parts of modified diatomaceous earth;

[0039] 3-4 parts lignin;

[0040] 8-10 parts of modified attapulgite;

[0041] 10-20 parts water.

[0042] The specific components and their weight percentages of the modified diatomaceous earth are as follows: 80-90 parts diatomaceous earth; 10-15 parts maifanite; 1-2 parts nano carbon; 1-2 parts ascorbic acid; 1-2 parts coix seed oil; 1-2 parts sodium dodecylbenzenesulfonate; 1-2 parts zinc gluconate; and 2-3 parts dandelion powder.

[0043] The specific components and their weight percentages of the modified attapulgite are as follows: attapulgite 100-120 parts; sodium carbonate 1-2 parts; alumina 2-3 parts; magnesium oxide 2-3 parts; titanium sulfate 10-12 parts; white sugar 2-3 parts; sodium lignosulfonate 2-3 parts; jade powder 10-12 parts; ammonium molybdate 1-2 parts; chromium oxide 2-3 parts; morpholine 1-2 parts; water 5-10 parts.

[0044] The preparation method of the above-mentioned pressure-resistant and bactericidal modified activated carbon adsorbent includes the following specific steps:

[0045] S1. Preparation of oxidatively modified activated carbon from sludge

[0046] Dry sludge is placed in a carbonization furnace and carbonized at 600-800℃ in a nitrogen atmosphere. The carbonized product is then placed in an oxidant solution for oxidative modification and finally dried to obtain oxidized modified sludge activated carbon.

[0047] S2, Preparation of modified diatomaceous earth

[0048] Diatomaceous earth and maifanite are calcined in a furnace at 550℃ for 3-4 hours, removed, soaked in hydrochloric acid solution for 4-5 hours, filtered, washed repeatedly with water, dried, added to water, and simultaneously added nano carbon, ascorbic acid, and zinc gluconate. The mixture is then ground to obtain a slurry, spray-dried, and then mixed with coix seed oil, sodium dodecylbenzene sulfonate, dandelion powder, and the dried powder. The mixture is then ground and dispersed to obtain modified diatomaceous earth.

[0049] S3. Preparation of modified attapulgite soil

[0050] Attapulgite clay, white sugar, sodium lignosulfonate, and sodium carbonate are mixed and kneaded into a mud-like consistency with water. The mud is then placed in a calcining furnace and calcined at 950°C for 3-4 hours. The mud is then removed and mixed with alumina, magnesium oxide, titanium sulfate, jade powder, ammonium molybdate, chromium oxide, morpholine, and water. The mixture is ground to obtain a 200-300 mesh slurry, which is then spray-dried to obtain modified attapulgite clay.

[0051] S4. Preparation of activated carbon adsorbent

[0052] Oxidized modified sludge activated carbon, wheat straw powder, rock wool fiber, bamboo fiber, cerium oxide, and lignin are added to water, heated to 80-90℃, and ground for 40-60 minutes. Then ammonium persulfate is added, stirred for 1-2 hours, and ground again to obtain a 200-300 mesh slurry. This slurry is spray-dried, mixed evenly with modified diatomaceous earth and modified attapulgite, and sent to a treatment furnace. It is then treated at 350-380℃ for 3-4 hours and removed to obtain the activated carbon adsorbent.

[0053] The oxidizing agent solution in step S1 is benzoyl peroxide solution. Specific Implementation Example 1:

[0055] A pressure-resistant and bactericidal modified activated carbon adsorbent, the specific components and their weight parts are as follows:

[0056] 120 parts of oxidatively modified activated carbon for sludge;

[0057] 20 parts wheatgrass powder;

[0058] 15 parts rock wool fiber;

[0059] 10 parts bamboo fiber;

[0060] 2 parts cerium oxide;

[0061] 1 part ammonium persulfate;

[0062] 70 parts of modified diatomaceous earth;

[0063] 3 parts lignin;

[0064] 8 parts of modified attapulgite clay;

[0065] 10 parts water.

[0066] The specific components and their weight percentages of the modified diatomaceous earth are as follows: 80 parts diatomaceous earth; 10 parts maifanite; 1 part nano carbon; 1 part ascorbic acid; 1 part coix seed oil; 1 part sodium dodecylbenzenesulfonate; 1 part zinc gluconate; and 2 parts dandelion powder.

[0067] The specific components and their weight percentages of the modified attapulgite are as follows: 100 parts attapulgite; 1 part sodium carbonate; 2 parts alumina; 2 parts magnesium oxide; 10 parts titanium sulfate; 2 parts white sugar; 2 parts sodium lignosulfonate; 10 parts jade powder; 1 part ammonium molybdate; 2 parts chromium oxide; 1 part morpholine; and 5 parts water.

[0068] The preparation method of the above-mentioned pressure-resistant and bactericidal modified activated carbon adsorbent includes the following specific steps:

[0069] S1. Preparation of oxidatively modified activated carbon from sludge

[0070] Dry sludge is placed in a carbonization furnace and carbonized at 600°C in a nitrogen atmosphere. The carbonized product is then placed in an oxidant solution for oxidative modification and finally dried to obtain oxidized sludge activated carbon.

[0071] S2, Preparation of modified diatomaceous earth

[0072] Diatomaceous earth and maifanite were calcined in a furnace at 550°C for 3 hours, removed, soaked in hydrochloric acid solution for 4 hours, filtered, washed repeatedly with water, dried, added to water, and simultaneously added nano-carbon, ascorbic acid, and zinc gluconate. The mixture was then ground to obtain a slurry, spray-dried, and then mixed with coix seed oil, sodium dodecylbenzene sulfonate, dandelion powder, and the dried powder. The mixture was then ground and dispersed to obtain modified diatomaceous earth.

[0073] S3. Preparation of modified attapulgite soil

[0074] Attapulgite clay, white sugar, sodium lignosulfonate, and sodium carbonate were mixed and kneaded into a mud-like consistency with water. The mixture was then placed in a calcining furnace and calcined at 950°C for 3 hours. The mixture was then removed and mixed with alumina, magnesium oxide, titanium sulfate, jade powder, ammonium molybdate, chromium oxide, morpholine, and water. The mixture was ground to obtain a 200-mesh slurry, which was then spray-dried to obtain modified attapulgite clay.

[0075] S4. Preparation of activated carbon adsorbent

[0076] Oxidized modified sludge activated carbon, wheat straw powder, rock wool fiber, bamboo fiber, cerium oxide, and lignin were added to water, heated to 80°C, and ground for 40 minutes. Then ammonium persulfate was added, stirred for 1 hour, and ground again to obtain a 200-mesh slurry. The slurry was spray-dried, mixed evenly with modified diatomaceous earth and modified attapulgite, and sent to a treatment furnace. It was treated at 350°C for 3 hours and then removed to obtain activated carbon adsorbent.

[0077] The oxidizing agent solution in step S1 is benzoyl peroxide solution. Specific Implementation Example 2:

[0079] A pressure-resistant and bactericidal modified activated carbon adsorbent, the specific components and their weight parts are as follows:

[0080] 150 parts of oxidatively modified activated carbon for sludge;

[0081] 30 parts wheatgrass powder;

[0082] 20 parts rock wool fiber;

[0083] 15 parts bamboo fiber;

[0084] 3 parts cerium oxide;

[0085] 2 parts ammonium persulfate;

[0086] 80 parts of modified diatomaceous earth;

[0087] 4 parts lignin;

[0088] 10 parts of modified attapulgite clay;

[0089] 20 parts water.

[0090] The specific components and their weight percentages of the modified diatomaceous earth are as follows: 90 parts diatomaceous earth; 15 parts maifanite; 2 parts nano carbon; 2 parts ascorbic acid; 2 parts coix seed oil; 2 parts sodium dodecylbenzenesulfonate; 2 parts zinc gluconate; and 3 parts dandelion powder.

[0091] The specific components and their weight percentages of the modified attapulgite are as follows: attapulgite 120 parts; sodium carbonate 2 parts; alumina 3 parts; magnesium oxide 3 parts; titanium sulfate 12 parts; white sugar 3 parts; sodium lignosulfonate 3 parts; jade powder 12 parts; ammonium molybdate 2 parts; chromium oxide 3 parts; morpholine 2 parts; water 10 parts.

[0092] The preparation method of the above-mentioned pressure-resistant and bactericidal modified activated carbon adsorbent includes the following specific steps:

[0093] S1. Preparation of oxidatively modified activated carbon from sludge

[0094] Dry sludge is placed in a carbonization furnace and carbonized at 800°C in a nitrogen atmosphere. The carbonized product is then placed in an oxidant solution for oxidative modification and finally dried to obtain oxidized modified sludge activated carbon.

[0095] S2, Preparation of modified diatomaceous earth

[0096] Diatomaceous earth and maifanite were calcined in a furnace at 550°C for 4 hours, removed, soaked in hydrochloric acid solution for 5 hours, filtered, washed repeatedly with water, dried, added to water, and simultaneously added nano-carbon, ascorbic acid, and zinc gluconate. The mixture was then ground to obtain a slurry, spray-dried, and then mixed with coix seed oil, sodium dodecylbenzene sulfonate, dandelion powder, and the dried powder. The mixture was then ground and dispersed to obtain modified diatomaceous earth.

[0097] S3. Preparation of modified attapulgite soil

[0098] Attapulgite clay, white sugar, sodium lignosulfonate, and sodium carbonate were mixed, and then water was added to form a mud-like consistency. The mud was then placed in a calcining furnace and calcined at 950°C for 4 hours. The mud was then removed and mixed with alumina, magnesium oxide, titanium sulfate, jade powder, ammonium molybdate, chromium oxide, morpholine, and water. The mixture was ground to obtain a 300-mesh slurry, which was then spray-dried to obtain modified attapulgite clay.

[0099] S4. Preparation of activated carbon adsorbent

[0100] Oxidized modified sludge activated carbon, wheat straw powder, rock wool fiber, bamboo fiber, cerium oxide, and lignin were added to water, heated to 90°C, and ground for 60 minutes. Then ammonium persulfate was added, stirred for 2 hours, and ground again to obtain a 300-mesh slurry. The slurry was spray-dried, mixed evenly with modified diatomaceous earth and modified attapulgite, and sent to a treatment furnace for treatment at 380°C for 4 hours. The slurry was then removed to obtain the activated carbon adsorbent.

[0101] The oxidizing agent solution in step S1 is benzoyl peroxide solution. Specific Implementation Example 3:

[0103] A pressure-resistant and bactericidal modified activated carbon adsorbent, the specific components and their weight parts are as follows:

[0104] 140 parts of oxidatively modified activated carbon from sludge;

[0105] 25 parts wheatgrass powder;

[0106] 18 parts rock wool fiber;

[0107] 13 parts bamboo fiber;

[0108] 2 parts cerium oxide;

[0109] 2 parts ammonium persulfate;

[0110] 75 parts of modified diatomaceous earth;

[0111] 3 parts lignin;

[0112] 9 parts of modified attapulgite clay;

[0113] 15 parts water.

[0114] The specific components and their weight percentages of the modified diatomaceous earth are as follows: 85 parts diatomaceous earth; 12 parts maifanite; 1 part nano carbon; 2 parts ascorbic acid; 1 part coix seed oil; 2 parts sodium dodecylbenzenesulfonate; 1 part zinc gluconate; and 3 parts dandelion powder.

[0115] The specific components and their weight percentages of the modified attapulgite are as follows: attapulgite 110 parts; sodium carbonate 1 part; alumina 3 parts; magnesium oxide 2 parts; titanium sulfate 11 parts; white sugar 2 parts; sodium lignosulfonate 3 parts; jade powder 11 parts; ammonium molybdate 1 part; chromium oxide 3 parts; morpholine 1 part; water 8 parts.

[0116] The preparation method of the above-mentioned pressure-resistant and bactericidal modified activated carbon adsorbent includes the following specific steps:

[0117] S1. Preparation of oxidatively modified activated carbon from sludge

[0118] Dry sludge is placed in a carbonization furnace and carbonized at 700°C in a nitrogen atmosphere. The carbonized product is then placed in an oxidant solution for oxidative modification and finally dried to obtain oxidized modified sludge activated carbon.

[0119] S2, Preparation of modified diatomaceous earth

[0120] Diatomaceous earth and maifanite were calcined in a furnace at 550°C for 3 hours, removed, soaked in hydrochloric acid solution for 5 hours, filtered, washed repeatedly with water, dried, added to water, and simultaneously added nano-carbon, ascorbic acid, and zinc gluconate. The mixture was then ground to obtain a slurry, spray-dried, and then mixed with coix seed oil, sodium dodecylbenzene sulfonate, dandelion powder, and the dried powder. The mixture was then ground and dispersed to obtain modified diatomaceous earth.

[0121] S3. Preparation of modified attapulgite soil

[0122] Attapulgite clay, white sugar, sodium lignosulfonate, and sodium carbonate were mixed, added to water and kneaded into a mud-like consistency. The mud was then placed in a calcining furnace and calcined at 950°C for 3 hours. The mud was then removed, mixed with alumina, magnesium oxide, titanium sulfate, jade powder, ammonium molybdate, chromium oxide, morpholine, and water, and ground to obtain a 300-mesh slurry. The slurry was then spray-dried to obtain modified attapulgite clay.

[0123] S4. Preparation of activated carbon adsorbent

[0124] Oxidized modified sludge activated carbon, wheat straw powder, rock wool fiber, bamboo fiber, cerium oxide, and lignin were added to water, heated to 85°C, and ground for 50 minutes. Then ammonium persulfate was added, stirred for 1 hour, and ground again to obtain a 300-mesh slurry. The slurry was spray-dried, mixed evenly with modified diatomaceous earth and modified attapulgite, and sent to a treatment furnace. It was treated at 360°C for 3 hours and then removed to obtain activated carbon adsorbent.

[0125] The oxidizing agent solution in step S1 is benzoyl peroxide solution.

[0126] This invention uses sludge to prepare activated carbon, effectively replacing traditional materials such as charcoal and coal. This not only saves resources but also enables waste utilization and reduces the production cost of activated carbon adsorbents. The addition of rock wool fiber and bamboo fiber increases the compressive strength and specific surface area of ​​the activated carbon adsorbent, thereby improving porosity. Cerium oxide and ammonium persulfate can rapidly decompose organic matter, improving adsorption treatment efficiency.

[0127] The present invention has been described above with reference to specific embodiments. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any improvements made using the inventive concept and technical solution of the present invention, or direct application to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A pressure-resistant and bactericidal modified activated carbon adsorbent, characterized in that, Its specific components and their weight percentages are as follows: 120-150 parts of oxidatively modified activated carbon for sludge; 20-30 parts wheatgrass powder; 15-20 parts rock wool fiber; 10-15 parts bamboo fiber; 2-3 parts of cerium oxide; 1-2 parts of ammonium persulfate; 70-80 parts of modified diatomaceous earth; 3-4 parts lignin; 8-10 parts of modified attapulgite; 10-20 parts water.

2. The pressure-resistant and bactericidal modified activated carbon adsorbent according to claim 1, characterized in that, The specific components and their weight percentages of the modified diatomaceous earth are as follows: 80-90 parts diatomaceous earth; 10-15 parts maifanite; 1-2 parts nano carbon; 1-2 parts ascorbic acid; 1-2 parts coix seed oil; 1-2 parts sodium dodecylbenzenesulfonate; 1-2 parts zinc gluconate; and 2-3 parts dandelion powder.

3. The pressure-resistant and bactericidal modified activated carbon adsorbent according to claim 2, characterized in that, The specific components and their weight percentages of the modified attapulgite are as follows: attapulgite 100-120 parts; sodium carbonate 1-2 parts; alumina 2-3 parts; magnesium oxide 2-3 parts; titanium sulfate 10-12 parts; white sugar 2-3 parts; sodium lignosulfonate 2-3 parts; jade powder 10-12 parts; ammonium molybdate 1-2 parts; chromium oxide 2-3 parts; morpholine 1-2 parts; water 5-10 parts.

4. A method for preparing the pressure-resistant and bactericidal modified activated carbon adsorbent as described in claim 3, characterized in that, The specific steps are as follows: S1. Preparation of oxidatively modified activated carbon from sludge Dry sludge is placed in a carbonization furnace and carbonized at 600-800℃ in a nitrogen atmosphere. The carbonized product is then placed in an oxidant solution for oxidative modification and finally dried to obtain oxidized modified sludge activated carbon. S2, Preparation of modified diatomaceous earth Diatomaceous earth and maifanite are calcined in a furnace at 550℃ for 3-4 hours, removed, soaked in hydrochloric acid solution for 4-5 hours, filtered, washed repeatedly with water, dried, added to water, and simultaneously added nano carbon, ascorbic acid, and zinc gluconate. The mixture is then ground to obtain a slurry, spray-dried, and then mixed with coix seed oil, sodium dodecylbenzene sulfonate, dandelion powder, and the dried powder. The mixture is then ground and dispersed to obtain modified diatomaceous earth. S3. Preparation of modified attapulgite soil Attapulgite clay, white sugar, sodium lignosulfonate, and sodium carbonate are mixed and kneaded into a mud-like consistency with water. The mud is then placed in a calcining furnace and calcined at 950°C for 3-4 hours. The mud is then removed and mixed with alumina, magnesium oxide, titanium sulfate, jade powder, ammonium molybdate, chromium oxide, morpholine, and water. The mixture is ground to obtain a 200-300 mesh slurry, which is then spray-dried to obtain modified attapulgite clay. S4. Preparation of activated carbon adsorbent Oxidized modified sludge activated carbon, wheat straw powder, rock wool fiber, bamboo fiber, cerium oxide, and lignin are added to water, heated to 80-90℃, and ground for 40-60 minutes. Then ammonium persulfate is added, stirred for 1-2 hours, and ground again to obtain a 200-300 mesh slurry. This slurry is spray-dried, mixed evenly with modified diatomaceous earth and modified attapulgite, and sent to a treatment furnace. It is then treated at 350-380℃ for 3-4 hours and removed to obtain the activated carbon adsorbent.

5. The preparation method of the pressure-resistant and bactericidal modified activated carbon adsorbent according to claim 4, characterized in that, The oxidizing agent solution in step S1 is benzoyl peroxide solution.