KR102348305B1 - Formaldehyde removal adsorption comprising coffee waste and acid mine drainage sludge, and method for manufacturing the same - Google Patents

Abstract

The present specification relates to an absorbent capable of absorbing and removing formaldehyde (HCHO) in the air by using acid mine drainage sludge and coffee waste (CW).

Description

Adsorbent for removing formaldehyde, including coffee grounds and acid mine drainage sludge, and manufacturing method thereof

Disclosed herein are an adsorbent for removing formaldehyde comprising coffee grounds and acidic acid mine drainage sludge and a method for preparing the same. More specifically, it relates to an adsorbent for removing formaldehyde from the air, comprising coffee grounds generated during coffee production and acidic acid mine drainage sludge obtained by precipitating and drying high-concentration acidic acid mine drainage generated inside an abandoned mine, and a method for manufacturing the same .

With the development of various industries and the consequent economic growth, various hazardous substances amounting to a huge amount in the manufacturing industry are generated, causing serious environmental pollution problems, and consequently, a threat to health is also occurring as secondary damage. Among various pollutants, Volatile Organic Compounds (VOCs) are the main culprits of various environmental problems, and strict management is required, such as being designated as specific air hazardous substances as related regulations are strengthened.

Volatile organic compounds are a generic term for liquid or gaseous organic compounds that evaporate easily into the atmosphere due to their low boiling point. Causes convulsions and carcinogenicity (B1).

Meanwhile, coffee is the world's favorite food, and the size of the domestic coffee market is estimated to be 11.7 trillion won in 2017, which has grown more than three times compared to 3 trillion won 10 years ago.

Annual domestic coffee import weight (Customs Administration, import and export trade statistics) base year 2008 2010 2012 2014 2016 2018 ton 102,086 111,625 106,119 133,732 153,030 158,385

In addition, the number of cups of coffee consumed by the entire Korean population in one year is 512 cups per person per year, and Korea is the world's third largest coffee consumer. However, the undiluted solution extracted from coffee beans is 0.2%, while the remaining 99.8% is all thrown away after use. They are collected together with household waste in a volume-based bag and then incinerated.

Annual domestic coffee grounds emissions (Ministry of Environment) base year 2014 2016 2017 ton 103,000 124,000 129,500

Therefore, it is urgently needed to develop a technology that can solve the above problems by recycling coffee by-products that are thrown away in large quantities every year.

Korean Patent Publication No. 10-2018-0125758 (published on November 26, 2018)

Yang, Z.; Miao, H.; Rui, Z.; Ji, H. 2019. Enhanced Formaldehyde Removal from Air Using Fully Biodegradable Chitosan Grafted β-Cyclodextrin Adsorbent with Weak Chemical Interaction. Polymers 11, 276. Carter, E. M., Katz, L. E., Speitel, G. E. and Ramirez, D. 2011. Gas-Phase Formaldehyde Adsorption Isotherm Studies on Activated Carbon: Correlations of Adsorption Capacity to Surface Functional Group Density. Environmental Science & Technology 45(15), 6498-6503. Kalantarifard, A., Gon, J. and Yang, G. 2016. Formaldehyde Adsorption into Clinoptilolite Zeolite Modified with the Addition of Rich Materials and Desorption Performance Using Microwave Heating. Terrestrial, Atmospheric and Oceanic Sciences 27, 865.

In one aspect of the present invention, an object of the present invention is to economically and efficiently remove formaldehyde using an adsorbent prepared using industrial waste coffee grounds and acid mine drainage sludge.

In one aspect of the present invention, there is provided an adsorbent for removing formaldehyde, comprising coffee grounds and acidic acid mine drainage sludge.

In another aspect, the column unit comprising the above-described adsorbent for removing formaldehyde; injection gas concentration measuring unit; and an exhaust gas concentration measuring unit; provides a formaldehyde removal device, including.

In another aspect, there is provided a method for preparing the above-described adsorbent for removing formaldehyde, the method comprising: preparing coffee grounds; preparing acid mine drainage sludge; and mixing and heat-treating the coffee grounds and acidic acid mine drainage sludge; It provides a method for preparing an adsorbent for removing formaldehyde, comprising a.

In another aspect, the present invention provides a method for removing formaldehyde using the above-described adsorbent for removing formaldehyde.

The adsorbent for removing formaldehyde according to an embodiment of the present invention can effectively and economically adsorb formaldehyde, including coffee grounds and acidic acid mine drainage sludge.

According to one aspect of the present invention, economic loss or incineration generated to treat acidic mine drainage sludge, which is a waste by-product generated during the treatment of waste generated in the mining industry, and coffee grounds, which is an industrial waste by-product generated during coffee production , it is possible to prevent environmental pollution problems caused by landfilling.

According to another aspect of the present invention, the production cost of the adsorbent can be greatly reduced by manufacturing the adsorbent by recycling discarded wastes, and the adsorbent can be reused, which is environmentally friendly.

1A is a photograph of a mixture of dried coffee grounds, which are raw materials of an adsorbent for removing formaldehyde according to an embodiment of the present invention, and acidic acid mine drainage sludge. Specifically, the brown part is AMDS (acid mine drainage sludge), and the black part is coffee grounds.
1b is a photograph of coffee grounds biocha containing acidic acid mine drainage sludge after heat treatment.
2 is a flow chart of the manufacturing steps of the present invention.
3 is a schematic configuration diagram of an apparatus for manufacturing an adsorbent for removing formaldehyde according to an embodiment of the present invention.
4A-4B are scanning electron microscope (SEM) images of an adsorbent for removing formaldehyde prepared according to an embodiment of the present invention. FIG. 4A is a comparative example, and FIG. 4B is a scanning electron microscope of Example 1. It is an image.
5 is a graph showing the comparative results of formaldehyde removal at a formaldehyde concentration of about 11-13 ppm of the adsorbents prepared in Examples and Comparative Examples of the present invention.
6 is a table showing the conditions and Qe values of the experiments before and after formaldehyde removal of the adsorbents prepared in Examples and Comparative Examples of the present invention.
7 is a table showing the conditions and Qe values of a formaldehyde removal experiment using different adsorbents.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The embodiments of the present invention disclosed in the text are illustrated for the purpose of explanation only, and the embodiments of the present invention may be embodied in various forms and should not be construed as being limited to the embodiments described in the text. .

The present invention can make various changes and can have various forms, and the embodiments are not intended to limit the present invention to a specific disclosed form, and all changes, equivalents or substitutes included in the spirit and scope of the present invention should be understood as including

In the present specification, when a part "includes" a certain component, this means that other components may be further included rather than excluding other components unless otherwise stated.

As used herein, "mine drainage" is water flowing out of the mine, high in heavy metal content, and low in pH. Therefore, acid mine drainage must be neutralized and oxidized to have an appropriate pH before flowing into river water and groundwater, and a large amount of dissolved iron Various heavy metals including

Adsorbent for Formaldehyde Removal

In exemplary embodiments of the present invention, there is provided an adsorbent for removing formaldehyde, comprising coffee grounds and acidic acid mine drainage sludge.

The adsorbent for removing formaldehyde according to an embodiment of the present invention is a bio-char produced by carbonizing coffee grounds thrown away as waste in a workplace together with acid mine drainage sludge flowing out of a mine, and it is possible to reduce manufacturing costs, Acidic acid mine drainage sludge is deposited on the surface of the coffee grounds biocha to increase the surface area and maximize the formaldehyde removal ability.

In addition, according to one aspect of the present invention, the already used adsorbent can be reused after drying in an oven at 60° C. or higher for 12 hours, which can be said to be eco-friendly.

In one embodiment, the coffee grounds are coffee grounds biochar (Biochar), and acidic acid mine drainage sludge may be deposited on the surface of the coffee grounds biochar (Biochar).

In one embodiment, the acidic acid mine drainage sludge contains a divalent to trivalent metal or a divalent to trivalent metalloid element, and the divalent to trivalent metal or divalent to trivalent metalloid element is Fe, Ca , Si and Al may be at least one selected from the group consisting of.

In one embodiment, the acidic acid mine drainage sludge is dried acidic acid mine drainage sludge, and when the dried acidic acid mine drainage sludge is analyzed by X-ray flourescence spectrometry (XRF), the bivalent to 3 The content of iron (Fe) among valent metals or divalent to trivalent metalloid elements may be 70% or more.

In one embodiment, the average particle diameter of the acidic acid mine drainage sludge may be 0.3 to 10.0 μm. The size of the acidic acid mine drainage sludge may be 45 μm or less, and the average particle size means that 93% or more of the particle diameter of the acidic acid acid drainage sludge falls within the range of 0.3 - 10.0 μm.

In one embodiment of the present invention, by using the acidic acid mine drainage sludge dried in powder form after active treatment with a strong base material, the acidic acid acid drainage sludge having excellent formaldehyde adsorption function is uniformly applied to the coffee grounds biocha. It may exist in a dispersed state.

Specifically, when the cations such as Na, Ca, and Fe in the acidic acid mine drainage sludge are mixed with the coffee grounds and increase on the surface of the adsorbent, the Lewis acidic site where formaldehyde can react increases and the chemical adsorption capacity is improved, and when the sludge is added As the pore surface area increases, the removal of formaldehyde increases and the physical adsorption capacity is improved, and at the same time, the formaldehyde adsorption capacity of the adsorbent can be improved.

In one embodiment, the weight ratio of the coffee grounds and acidic acid mine drainage sludge may be 1: 0.15 to 1: 2, for example, the weight ratio is 1: 0.15 or more, 1: 0.2 or more, 1: 0.3 or more, 1: 0.4 or more , 1: 0.5 or more, 1: 0.6 or more, 1: 0.7 or more, 1: 0.8 or more, 1: 0.9 or more, 1: 1 or more, 1: 1.1 or more, 1: 1.3 or more, 1: 1.5 or more, 1: 1.7 or more , 1: may be 1.9 or more, 1: 2 or less, 1: 1.9 or less, 1: 1.8 or less, 1: 1.7 or less, 1: 1.6 or less, 1: 1.5 or less, 1: 1.4 or less, 1: 1.3 or less, 1: 1.2 or less, 1: 1.1 or less. When the weight ratio is less than 1: 0.15, the formaldehyde adsorption capacity may decrease, and if it is more than 1: 2, the yield may decrease.

In one embodiment, in addition to the coffee grounds, as long as it can form an adsorbent together with the acidic acid mine drainage sludge, it may further include without particular limitation.

Specifically, it is preferable to use a material that is readily available and can be carbonized, and specific examples thereof may include wood chips, seaweeds, and shells of various plants.

In one embodiment, the formaldehyde removal efficiency of the adsorbent for removing formaldehyde may be 60% or more, preferably 67.9% or more.

In another embodiment, the formaldehyde adsorption capacity of the adsorbent for removing formaldehyde may be 0.1 g/g, 0.5 g/g, 1 g/g, 1.5 g/g, It may be 2 g/g, may be 2.5 g/g, and may preferably be 3 g/g or more.

In the present specification, the removal efficiency is based on the result of calculating the formaldehyde removed based on the formaldehyde injected up to the exhaust point (detection of 95% or more of the injection concentration), and the adsorption capacity is the adsorbent filled with the removed formaldehyde It is based on the result calculated by dividing by weight.

Specifically, the adsorption capacity was calculated as the amount of formaldehyde removed based on the total amount of formaldehyde until the exhaust point (detection of 95% or more of the injection concentration) by performing the example as a column experiment. Calculation up to the breakthrough point (detection of more than 5% of the infusion concentration) may increase the removal rate and decrease the adsorption capacity.

In one embodiment, the adsorbent for removing formaldehyde may include a plurality of pores therein, and may remove formaldehyde in the air.

Specifically, as a result of BET analysis, the mesopore volume of the adsorbent according to an embodiment of the present invention may be 0.05 cm ³ /g or more, preferably 0.080718 cm ³ /g, and the average pore size is 1 to 10 nm, preferably 5.944 nm, and the mesopore surface area may be 30 m ² /g or more, preferably 33.677 m ² /g.

The results that can be obtained from BET analysis are largely the specific surface area (Ap), the pore size of the adsorbent, and the volume in the adsorbent (Vp). Since pores mainly involved in adsorption are mesopores (2-50 nm) and/or macropores, the number of mesopores and/or macropores can be measured.

In the adsorbent according to one embodiment of the present invention, the specific surface area of coffee grounds is synthesized with AMDS and modified with iron oxide particles on the surface, resulting in a significant increase in the specific surface area of the synthetic adsorbent, particularly the specific surface area of mesopores.

In another exemplary embodiment of the present invention, the column unit comprising the above-described adsorbent for removing formaldehyde; injection gas concentration measuring unit; and an exhaust gas concentration measurement unit; it provides a formaldehyde removal device, including.

As shown in FIG. 3 , the formaldehyde removal adsorbent may be included in a column, and a gas (HCHO, O ₂ ) containing formaldehyde may be injected into the column to pass through the column. The column fixes both sides of the adsorbent according to an embodiment of the present invention with glass wool, and further comprises glass beads on the glass wool, respectively, so that the adsorbent in powder form It can be filled so that the reaction does not scatter inside the column and the reaction occurs evenly.

In addition, one side includes an injection gas concentration measuring unit for measuring the formaldehyde concentration in the gas injected from outside the device, and the other side includes an exhaust gas concentration measuring unit for measuring the formaldehyde concentration in the gas passing through the formaldehyde removal adsorbent By doing so, it is possible to measure the extent to which formaldehyde is removed in real time. Alternatively, the injection gas concentration measuring unit and the exhaust gas concentration measuring unit are installed in one place in the device, and in FIG. 3, open ①, close ② to measure the concentration of the injection part, close ① and open ② at the same time It is possible to measure the exhaust gas concentration in the part described as FT-IR.

Adsorbent manufacturing method for formaldehyde removal

In another exemplary embodiment of the present invention, there is provided a method for preparing the above-described adsorbent for removing formaldehyde, the method comprising: preparing coffee grounds; preparing acid mine drainage sludge; and mixing and heat-treating the coffee grounds and acidic acid mine drainage sludge; It provides a method for preparing an adsorbent for removing formaldehyde, including (see FIG. 2).

According to an embodiment of the present invention, an adsorbent for various purposes can be manufactured according to a material to be added by applying a biochar manufacturing method made by heating under a limited oxygen condition. In addition, it is possible to maximize the reaction surface area by adding acidic acid mine drainage sludge compared to the conventional biochar removal method, so it has excellent adsorption capacity per weight of the adsorbent.

For example, the adsorbent according to one embodiment of the present invention has ^{a specific surface area of 60 m 2} /g or more (preferably 64.796 m ² /g), and an adsorbent containing only coffee grounds (specific surface area 1.7538 m ² /g) and In comparison, it can exhibit a remarkably excellent adsorption capacity.

In one embodiment, the step of preparing the coffee grounds comprises the steps of drying the coffee grounds; pulverizing the dried coffee grounds into a powder; and adjusting the particle size of the powdered coffee grounds.

The coffee grounds may be used to recover coffee grounds generated during the production of coffee at a coffee shop, for example, Carpe day coffee (trade name) of Brownhouse co., a Korean manufacturer.

For example, preparing the coffee grounds may include drying the coffee grounds washed twice with deionized water in an oven at a temperature of 90 to 110° C. for 23 to 25 hours; and grinding the dried coffee grounds to prepare a powder having a particle size of 10 to 30 mesh;

In one embodiment, the preparing of the acidic acid mine drainage sludge comprises: drying the acidic acid mine drainage sludge; pulverizing and pulverizing the dried acidic acid mine drainage sludge; and adjusting the particle size of the powdered acidic acid mine drainage sludge.

Specifically, first, acidic acid mine drainage flowing out from the mine is collected, a strong base such as calcium hydroxide is added to precipitate it to form sludge, and after the reaction, the sludge is collected and air-dried to obtain acidic acid mine drainage sludge.

For example, the step of preparing the acidic acid mine drainage sludge may include precipitating the _{acidic acid mine drainage with calcium hydroxide (Ca(OH) 2 ), which is a basic material to sludge;} drying the sludged acidic acid mine drainage in an oven at a temperature of 30 to 40° C. for 23 to 25 hours; and pulverizing the dried acidic acid mine drainage sludge to prepare it in a powder form having a particle size of 80 to 100 mesh.

Thereafter, the mixture is mixed with coffee grounds in a certain ratio, and the mixture is put into a boat-type crucible made of a ceramic material to prepare a mixture as shown in FIG. 1A. In this case, the heat treatment preparation step may be carried out according to a conventional process, and the acidic acid mine drainage sludge and coffee grounds are the same as described above.

In one embodiment, the heat treatment may be carried out at a temperature of 790 to 810 °C under limited oxygen conditions. For example, it may be carried out by flowing only nitrogen gas through a closed glass furnace column.

For example, the heat treatment may be heated at a rate of 10° C./min., and the injection rate of the gas for heat treatment may be 200 mL/min.

In one embodiment, in the step of heat-treating by mixing the coffee grounds and the acidic acid mine drainage sludge, the coffee grounds and the acidic acid mine drainage sludge may be mixed in a weight ratio of 1: 0.15 to 2, for example, 1: 0.7 to 1 : 1.5 or 1: 0.9 to 1: 1.2 by weight ratio. When the weight ratio is less than 1: 0.15, the formaldehyde adsorption capacity may decrease, and if it is 1: 2 or more, the yield may decrease.

In one embodiment, the step of controlling the size of the adsorbent by filtering the heat-treated mixture through a sieve; may further include.

How to remove formaldehyde

Another exemplary embodiment of the present invention provides a method for removing formaldehyde using the above-described adsorbent for removing formaldehyde.

In one embodiment, the formaldehyde removal may be performed in air.

Hereinafter, the present invention will be described in detail with reference to preferred embodiments so that those skilled in the art can easily carry out the present invention. However, the present invention may be implemented in various different forms, and is not limited to the embodiments described herein.

Example

Sludge was made by collecting acid mine drainage from the mine H mine in Taebaek-si, Gangwon-do, and precipitating it with a strong base such as calcium hydroxide. After the reaction, the sludge was collected and air dried. After that, the air-dried sludge was crushed using a rubber mallet or a jade bowl, and then sieved through a 325 mesh to obtain an acidic mine drainage sludge in the form of a powder of 45 μm or less.

The results of X-ray fluorescence analysis (XRF) on the dried and sieved samples are shown in Table 3 below. The iron content was confirmed to be about 82.8%.

Results of XRF analysis of acid mine drainage sludge Element Fe S Ca Si Al Mn Mg Other Total AMDs (%) 82.8 0.82 10.20 2.42 1.47 1.21 0.24 0.85 100.0

In the same weight ratio as in Example 1 of Table 4 below, coffee grounds and acid mine drainage sludge were mixed, and placed in a boat-shaped crucible. The size of the adsorbent was varied, but in order to secure the reproducibility of the experiment, only the biochar with a size between 40-60 mesh and the biochar added with acidic acid mine drainage sludge was compared and used for the experiment.

Production of adsorbent with coffee grounds and acid mine drainage sludge Coffee grounds (by weight) Additives (weight) Example Coffee grounds (3.0 g) Dried acid mine drainage sludge (3.0 g) comparative example Coffee grounds (6.0 g) -

After the prepared coffee grounds and acidic acid mine drainage sludge mixture was transferred to the furnace, nitrogen gas (99.9999%) was injected into the closed glass furnace column under limited oxygen conditions, that is, at an injection rate of 200 mL/min. As a result of the heat treatment, an adsorbent for removing formaldehyde was prepared as shown in FIG. 1A. It can be confirmed that the brown part is AMDS (acid mine drainage sludge) and the black part is coffee grounds. 1b is a photograph of coffee grounds biocha containing acidic acid mine drainage sludge after heat treatment. In the case of the adsorbent, iron contained in a large amount in the acidic acid mine drainage sludge is magnetic even after heat treatment, so it can be confirmed that the adsorbent contains a large amount of iron ions, which are cations.

For the adsorbent of the present invention, the results of measuring the mesopore volume, mesopore specific surface area, and average pore size for mesopores (2-50 nm) mainly involved in adsorption were as follows.

<BET analysis result>

Meso pore volume: 0.080718 cm ³ /g

Pore size: 5.944 nm

Meso pore surface area: 33.677 m ² /g

In addition, when the total specific surface area, not the mesopores, was measured, the specific surface area of the coffee grounds biocha was 1.7538 m ² /g, and the specific surface area of the AMDS biochar (adsorbent of the present invention) was 64.796 m ² /g. .

comparative example

An adsorbent was prepared in the same manner as in the above Example, except that acidic acid mine drainage sludge was not used in preparing the adsorbent (comparative example in Table 4).

test example

test example 1: Observation of adsorbent surface

In order to evaluate the formaldehyde absorption and removal effect of the absorbent according to an embodiment of the present invention, the absorbents prepared in Comparative Examples and Examples were analyzed and observed using a scanning electron microscope, and the results are shown in FIGS. 4A to 4B it was

Referring to this, as compared with the comparative example (FIG. 4a), in the case of the example (FIG. 4b), it can be confirmed that the acidic acid mine drainage sludge was added to the biocha made from coffee grounds.

test example 2: Acid mine drainage sludge Formaldehyde upon addition Removability evaluation

As shown in FIG. 3, after mixing formaldehyde and nitrogen using a mass flow controller (MFC), the formaldehyde concentration was injected at about 11-13 ppm, and at the middle part of the column made of pyrex material with a diameter of 2 cm. The real-time online analysis process was shown through FT-IR for reducing the amount of formaldehyde by sandwiching the adsorbents of Examples and Comparative Examples.

As a result of the analysis, as shown in FIGS. 5-7 , it was confirmed that the adsorbent of Example (CW+AMDs) had superior formaldehyde removal capacity per unit weight compared to other adsorbents.

In addition, by performing the example as a column experiment, the adsorption capacity result calculated as the amount of formaldehyde removed based on the total amount of formaldehyde until the exhaust point (detection of 95% or more of the injection concentration) is about 3 g/g ( As shown in Table 7, it was found to be 3,013 mg/g) (see FIG. 6 ). This is more than 10 times the number compared to the comparative examples of FIG. 7 .

Therefore, in the case of the adsorbent according to an embodiment of the present invention, the formaldehyde removal ability was confirmed 10 times or more compared to other adsorbents (FIG. 7), and the regeneration method is environmentally friendly with heat treatment instead of using chemicals .

Claims (15)

Containing coffee grounds and acid mine drainage sludge,
The coffee grounds are coffee grounds biochar (Biochar),
An adsorbent for removing formaldehyde, wherein acidic acid mine drainage sludge is deposited on the surface of the coffee grounds biochar. According to claim 1,
The acidic acid mine drainage sludge contains a divalent to trivalent metal or a divalent to trivalent metalloid element,
The divalent to trivalent metal or divalent to trivalent metalloid element is at least one selected from the group consisting of Fe, Ca, Si and Al, an adsorbent for removing formaldehyde. 3. The method of claim 2,
The acidic acid mine drainage sludge is dried acidic acid mine drainage sludge,
When the dried acidic acid mine drainage sludge was analyzed by X-ray flourescence spectrometry (XRF), the content of iron (Fe) among the divalent to trivalent metals or divalent to trivalent metalloid elements was 70% or more, adsorbent for removal of formaldehyde. According to claim 1,
The average particle diameter of the acidic acid mine drainage sludge is 0.3 to 2.0 μm, an adsorbent for removing formaldehyde. According to claim 1,
The weight ratio of the coffee grounds and acidic acid mine drainage sludge is 1: 0.15 to 2, an adsorbent for removing formaldehyde. According to claim 1,
The formaldehyde removal efficiency of the adsorbent for removing formaldehyde is 60% or more, the adsorbent for removing formaldehyde. A column unit comprising an adsorbent for removing formaldehyde according to any one of claims 1 to 6;
injection gas concentration measuring unit; and
Exhaust gas concentration measurement unit; Containing, formaldehyde removal device. As a method for manufacturing the adsorbent for removing formaldehyde according to any one of claims 1 to 6,
preparing coffee grounds;
preparing acid mine drainage sludge; and
heat-treating a mixture of the coffee grounds and acid mine drainage sludge; A method for preparing an adsorbent for removing formaldehyde, comprising a. 9. The method of claim 8,
The step of preparing the coffee grounds,
drying the coffee grounds;
pulverizing the dried coffee grounds into a powder; and
Controlling the particle size of the powdered coffee grounds; Containing, a method for producing an adsorbent for removing formaldehyde. 9. The method of claim 8,
The step of preparing the acidic acid mine drainage sludge,
drying the acid mine drainage sludge;
pulverizing and pulverizing the dried acidic acid mine drainage sludge; and
Controlling the particle size of the powdered acidic acid mine drainage sludge; Containing, a method for producing an adsorbent for removing formaldehyde. 9. The method of claim 8,
In the step of heat-treating by mixing the coffee grounds and acidic acid mine drainage sludge,
The coffee grounds and acid acid mine drainage sludge are mixed in a weight ratio of 1: 0.15 to 2, a method for producing an adsorbent for removing formaldehyde. 9. The method of claim 8,
Controlling the size of the adsorbent by filtering the heat-treated mixture through a sieve; further comprising, a method of manufacturing an adsorbent for removing formaldehyde. A method for removing formaldehyde using the adsorbent for removing formaldehyde according to any one of claims 1 to 6. 14. The method of claim 13,
The removal of the formaldehyde, the formaldehyde removal method that is made in air. delete

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