KR102536462B1 - Adsorbent using Coffee waste to remove Microplastics and Manufacturing method there of - Google Patents

Abstract

An adsorbent for removing microplastics present in an aqueous phase is disclosed. The adsorbent is an adsorbent in which the surface of coffee grounds is treated with a hydrogel, and is characterized in that the adsorption performance of microplastics is improved. By using this, it is possible to remove or recycle microplastics from coffee grounds, which are wastes on land, and wastes at sea.

Description

Adsorbent using Coffee waste to remove Microplastics and Manufacturing method there of}

The present invention relates to an adsorbent for adsorbing microplastics, and more particularly, to an adsorbent for removing microplastics in an aqueous system using coffee grounds, that is, coffee waste.

Recently, as the amount of plastic used increases, the amount of plastic that is discarded also increases. In particular, when plastic is discarded in water, it is decomposed by ultraviolet rays, heat, impact, etc., and floats in the water system as microplastics.

Microplastics pose risks due to various chemicals such as plasticizers, additives, pigments, and stabilizers added during processing, including the risks inherent in plastic itself.

When these chemicals are absorbed into the body, they are not decomposed and accumulated in the body, and are expected to cause great problems not only to marine organisms and humans that consume them, but also to the Earth's ecosystem.

Therefore, studies on the amount and distribution of marine plastics, pollution status, and toxicity caused by ingestion of microplastics are being actively conducted.

In addition, technologies for removing microplastics are being actively researched recently, and among them, membrane bioreactors and electrocoagulation methods are known as representative methods.

Membrane bioreactor is a biological wastewater treatment method using microorganisms. However, compared to the speed at which we consume plastics, the decomposition rate of microorganisms is very slow, so it has not yet entered the practical use stage.

Electrocoagulation is a method of generating heat with high-frequency electricity to collect and solidify scattered microplastic particles and then filtering them out.

Accordingly, there is an increasing demand for a technology for removing microplastics that is more effective, simple, and inexpensive.

On the other hand, as the consumption of coffee beans increases significantly, the amount of coffee waste remaining after extracting the coffee undiluted solution from the pulverized coffee beans is also increasing. The problem of recycling such coffee waste as a new resource is also attracting great attention, but it is currently classified as household waste and is 100% incinerated or landfilled.

According to statistics, it is estimated that the cost of processing 150,000 tons of coffee waste, which is generated annually only in Korea, will cost about 4.1 billion won as of 2021. Therefore, a lot of research is needed on how to utilize discarded coffee grounds.

In this regard, a study introduced in Patent Document 1 to remove impurities using coffee waste has been conducted, and this prior art introduces a technology of supporting nano-permanent iron on coffee waste to adsorb heavy metals.

That is, in that the prior art mainly targets heavy metals in the case of adsorption in a range of ion sizes, it is practically impossible to adsorb microplastics, which are particulate matter having a high hydrophobicity.

In addition, the case of using coffee waste to adsorb microplastics in the water system has not yet been introduced to the related industry.

Publication No. 10-2019-0134335 (2019.12.04.)

The present invention was developed to provide an efficient technology for recycling coffee waste as a new resource and simultaneously removing microplastics by using the discarded coffee waste as described above for adsorption removal of microplastics, in particular for removal of microplastics in water.

Specifically, the present invention provides a coffee waste treated with a hydrogel capable of adsorbing and removing microplastics present in a water system and a method for producing the same, while maintaining the reactivity between the coffee waste treated with the hydrogel and the microplastics. This allows for effective removal of microplastics.

According to one aspect of the present invention for achieving the above objects and other features of the present invention, the step of supporting the coffee waste in an organic solvent to elute the hydrophilic substance in the coffee waste; Washing the coffee grounds from which the hydrophilic material is eluted; Irradiating UV rays to the washed coffee grounds and drying them; Mixing the dried coffee ground powder with hydrogel powder and then soaking in an aqueous solution of calcium chloride to treat the coffee grounds as a hydrogel; and filtering and then drying the hydrogel-treated coffee waste.

According to one embodiment of the present invention, the organic solvent is characterized in that ethanol.

According to another embodiment of the present invention, the ultraviolet rays are characterized in that the wavelength range is 100nm to 300nm.

According to another embodiment of the present invention, the hydrogel powder is characterized by using a powder having porosity and swelling property during solidification.

According to another embodiment of the present invention, when mixing the hydrogel powder and the coffee ground powder, the mixing ratio is characterized in that the weight of the hydrogel powder to the coffee ground powder is 0.16 to 0.5 in weight ratio.

According to another embodiment of the present invention, an adsorbent for removing microplastics is provided by utilizing the coffee waste produced by the method for preparing the adsorbent.

According to another embodiment of the present invention, an adsorption system for removing microplastics using the adsorbent, wherein the system is connected to a water pump for raising polluted water containing microplastics, and is connected to the water pump to move the polluted water to a storage box. A supply pipe, a storage box containing coffee grounds treated with a hydrogel capable of adsorbing microplastics in the contaminated water while the contaminated water supplied from the supply pipe is stored, and discharging purified water from which microplastics in the contaminated water are removed Provided is an adsorption system including a drain pipe for

In the adsorbent for removing microplastics according to the present invention made of hydrogel-treated coffee waste, the reactivity between the hydrogel-treated coffee waste and microplastics is improved, resulting in very excellent adsorption and removal efficiency.

In addition, in the present invention, by using discarded coffee waste as a carrier for adsorbing microplastics in water, it can have great value as an eco-friendly technology that can recycle waste as a new resource.

1 is a process flow chart for explaining a method for preparing an adsorbent according to an embodiment of the present invention.
2 is a view of a solution obtained after passing contaminated water containing microplastics through an adsorbent using coffee waste.
3 to 5 are FE-SEM views showing states of microplastics attached to adsorbents using coffee waste.
6 is a view showing an adsorption system for removing microplastics using the adsorbent of the present invention.

Since the description of the present invention is only an embodiment for structural or functional description, the scope of the present invention should not be construed as being limited by the embodiments described in the text.

That is, since the embodiment can be changed in various ways and can have various forms, it should be understood that the scope of the present invention includes equivalents capable of realizing the technical idea.

In addition, since the object or effect presented in the present invention does not mean that a specific embodiment should include all of them or only such effects, the scope of the present invention should not be construed as being limited thereto.

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

The adsorbent according to an embodiment of the present invention is characterized in that it is coffee grounds treated with a hydrogel.

1 is a process flow chart for explaining a method for preparing an adsorbent according to an embodiment of the present invention.

Referring to FIG. 1, the manufacturing method of the coffee waste adsorbent of the present invention includes the steps of supporting the coffee waste in an organic solvent (S100), washing the coffee waste (S200), and irradiating ultraviolet (UV) rays (S300). , It includes a step of treating with a hydrogel (S400) and a step of drying after filtering (S500).

First, the step of supporting the coffee waste in an organic solvent (S100) is a step of extracting the coffee undiluted solution, collecting and drying the remaining coffee waste, and then supporting the coffee waste in an organic solvent for 10 minutes to 1 hour, preferably It is effective to hold for 30 minutes.

When the coffee grounds are supported for less than 10 minutes, the removal of hydrophilic substances is insufficient, and when supported for more than 1 hour, the amount of hydrophilic substances removed is unchanged, so it is appropriate to support them for 10 minutes to 1 hour.

At this time, by replacing the organic solvent with a new solvent once or twice, the hydrophilic material can be removed in a faster time.

As the organic solvent used in this step, acetone, alcohol, etc. may be used, and anhydrous ethanol is preferably used. Ethanol is effective in eluting the hydrophilic substances contained in the coffee waste, while minimizing the elution of caffeine, thereby making the surface of the coffee waste hydrophobic.

When the hydrophilic substance present in the coffee waste is eluted, the pores in the coffee waste increase and the surface area of the pores also increases. At the same time, as the hydrophilic material is removed, the surface of the coffee grounds becomes hydrophobic.

Microplastics to be removed through the present invention have hydrophobic surface characteristics, so it is difficult to adsorb when the surface of the coffee waste is hydrophilic, but if the surface of the coffee waste becomes hydrophobic, the hydrophobic microplastic can be easily attracted and adsorbed.

In this step, according to an embodiment, 1 kg of coffee grounds and 10 L of ethanol are mixed, stirred at room temperature to 45 ° C. for 30 minutes, and then filtered to separate solid coffee grounds and liquid components.

On the other hand, the coffee waste contains approximately 10 to 15% of protein, and the internal structure is affected by denaturation of the protein in the coffee waste by the solvent ethanol.

Next, the step of washing the coffee waste (S200) is a step of washing the coffee waste from which the hydrophilic material has been removed with pure water, filtering, and collecting the coffee waste. At this time, it is preferable to wash with pure water 2 to 3 times so that organic solvents or hydrophilic substances do not remain on the surface of the coffee grounds.

Next, the step of irradiating ultraviolet (UV) rays (S300) is a step of irradiating and drying the washed coffee waste for 12 hours at the same time.

The ultraviolet light has a wavelength range of 10 nm to 400 nm, and when it is out of this range, the effect obtained by irradiating the ultraviolet light does not occur.

Preferably, it is good to use ultraviolet rays having a wavelength of 100 nm to 300 nm. The reason is that when the wavelength is shorter than the above range, the decomposition rate of the hydrophilic material is slowed down. Conversely, if it is longer than the above range, the sterilizing power is lowered.

In this step, the hydrophilic substances remaining in the coffee waste are decomposed, and the effect of sterilizing the coffee waste occurs. Hydrophilic substances that are degraded at this time include polyphenols, vitamin C, tocopherol, and the like.

In addition, in this step, pores and external surface area in the coffee waste are increased through a decomposition process according to UV irradiation.

It is preferable to dry naturally with UV irradiation, but drying methods such as hot air drying other than natural drying are not limited.

Then, the step of treating with a hydrogel (S400) is a step of mixing the UV-treated coffee grounds with the hydrogel powder in a powder state, and then putting the mixture into an aqueous calcium chloride solution and stirring.

At this time, the concentration of the calcium chloride aqueous solution is adjusted at a rate of 1 to 5 g of calcium chloride per 100 ml of pure water, and preferably, an aqueous calcium chloride solution prepared by dissolving 2 g of calcium chloride per 100 ml of pure water is used.

If the amount of calcium chloride is less than the above range, less solidification by crosslinking occurs, and if the amount of calcium chloride is greater than the above range, the rate of solidification of the hydrogels without being attached to the coffee waste increases.

As the hydrogel powder, it is preferable to use a powder having porosity and swelling property during solidification, such as sodium alginate.

In this step, alginic acid reacts with calcium ions to solidify, that is, cross-linking occurs, and a water-insoluble alginate hydrogel is created.

A natural polymer called alginate acid is a natural polysaccharide and is a component of brown algae such as seaweed, and has good biocompatibility and low cost.

Since the polysaccharide of alginic acid has a negative charge, it can form a hydrogel relatively easily by combining with divalent cations to form an egg box structure.

The hydrogel powder is preferably mixed in the range of 0.16 to 0.5 based on the weight of the coffee grounds.

If the amount of the hydrogel powder is less than the above range, the ratio of the coffee waste to be treated is reduced, and if it is more than the above range, the efficiency is lowered and the amount of hydrogel solidified without adhering to the coffee waste increases.

When the alginate hydrogel is attached to the surface of the coffee waste, the surface of the coffee waste becomes hydrophobic.

Next, filtering and drying the coffee waste (S500) is a step of filtering and then drying the coffee waste surface-treated with the hydrogel.

At this time, as a material that can be used for filtering, a cloth filter or the like may be used.

<Experimental Example 1: Preparation of hydrogel-treated coffee waste adsorbent>

As described above, the adsorbent according to the present invention is composed of hydrogel-treated coffee grounds.

As an example of the method for preparing the adsorbent of the present invention, the adsorbent was prepared as follows.

(1) 20 g of coffee grounds were wrapped in a cloth and prepared by putting them in a beaker.

(2) Add 200ml of anhydrous ethanol to the beaker.

(3) Leave the cloth containing the coffee waste at room temperature for 30 minutes with slow stirring, then take the cloth with the coffee waste out of the beaker and recover the coffee waste inside.

(4) The coffee waste is washed.

(5) Dry the washed coffee grounds naturally under UV light for 12 hours.

(6) The coffee waste was mixed with 4 g of sodium alginate in a powder state, and then the mixture was slowly added to an aqueous calcium chloride solution (200 ml of water, 4 g of calcium chloride) for 1 minute. Stir.

(7) After filtering the mixture using a cloth, a coffee ground adsorbent treated with a hydrogel is obtained through a drying process.

<Experimental Example 2: Comparison of microplastic removal performance using the adsorbent prepared in Experimental Example 1>

After performing a microplastic removal experiment at room temperature using the adsorbent of the present invention prepared according to Experimental Example 1 above, the performance evaluation results with the comparative adsorbent are shown in Table 1 and FIG. 2.

Since there is no commercially available adsorbent for comparison, coffee waste treated with only ethanol before making the hydrogel-treated coffee waste in Experimental Example 1 (Comparative Example 2), coffee waste irradiated with ultraviolet rays after ethanol treatment (Comparative Example) 3) and Comparative Example 1 and Experimental Example 1 in which water-based microplastics were removed using only a cloth are shown in Table 1 and FIG. 2.

The experimental method was performed as follows. First, prepare coffee grounds to remove microplastics. Then, after preparing a contaminant composed of 1 g of acrylic powder, which is a type of microplastic, and 200 ml of water, the contaminant is passed through a device containing adsorbable coffee waste (FIG. 6).

Contaminants passing through the coffee waste were separately collected and permeability was evaluated for the amount of suspended matter, color of water, and amount of permeated water.

In addition, the coffee grounds through which contaminants passed were separately collected and FE-SEM images were obtained using Hitachi's FE (Field Emission)-SEM (scanning electron emission) equipment S-4800 device.

Experimental results related to adsorption performance will be described below.

Table 1 and FIG. 2 are the results of visually measuring the appearance of contaminants passing through the coffee waste.

Comparative Example 1
(cloth filter) Comparative Example 2
(ethanol-treated coffee waste) Comparative Example 3
(Ethanol + UV treated coffee waste) Example With or without float A lot of white floaters doesn't exist doesn't exist doesn't exist color after processing dull white brown brown clear yellow permeability height lowness middle height

First, in Comparative Example 1, which is the result of simply filtering the contaminants using a cloth filter, there is a large amount of suspended matter (acrylic powder), and the color of the water is turbid white, so it is effective to remove the acrylic powder using a cloth with large pores. It can be seen that it is not. (The leftmost sample in FIG. 2)

In the case of the filtering test (Comparative Example 2) using coffee grounds in which hydrophilic substances were removed with ethanol, it can be seen that visible suspended matter is removed, but when looking at the water color and water permeability results remaining after filtering, coffee grounds are lost along with contaminants, and acrylic It can be seen that the powder still remains in the contaminants (second sample from the left in Figure 2).

Here, the water permeability means the degree to which water passes when contaminated water passes through the adsorbent.

UV was irradiated after ethanol treatment, but in the case of coffee grounds not treated with hydrogel (Comparative Example 3), it seems to be improved compared to Comparative Example 2, but acrylic powder still seems to exist. (third sample from the left in Fig. 2)

In the case of the coffee grounds finally treated with the hydrogel, which is the result of the experiment of the present invention, there is no floating matter, and it can be seen that the acrylic powder is effectively removed from the results of the remaining water color or water permeability after filtering. (The rightmost sample in FIG. 2 )

In order to check the state of additionally adsorbed acrylic powder and coffee grounds, images were taken through a FE-SEM device. (FIGS. 3 to 5)

In the case of Comparative Example 2 (Fig. 3) and Comparative Example 3 (Fig. 4), spherical acrylic powder is attached to the outside of the coffee waste, but exists in a state that is easily detached, whereas in the case of the present invention Example (Fig. 5), the hydrogel powder Since the acrylic powder is firmly held inside the gel, it is difficult to desorb, so it can be seen that it is effective in removing the acrylic powder, which is a microplastic.

In particular, the hydrogel located on the surface of the coffee waste absorbs moisture in the liquid phase while swelling and absorbs microplastics together, and the absorbed microplastics are captured by the hydrophobic coffee waste.

Next, an adsorption system using the adsorbent will be described.

According to FIG. 6 , the system includes a water pump 10 , a supply pipe 20 , a storage box 30 and a drain pipe 40 .

Specifically, a water pump 10 that raises the contaminated water containing microplastics, a supply pipe 20 connected to the water pump 10 and moving the contaminated water to the storage box 30, and the supply pipe 20 It consists of a storage box 30 in which microplastics are adsorbed by an internal coffee waste adsorbent while the contaminated water supplied from the reservoir is stored, and a drain pipe 40 for discharging purified contaminated water.

Meshes 31 and 32 that function to prevent the coffee waste adsorbent from flowing out to the supply pipe 20 and the drain pipe 40 are installed at the inlet and outlet of the storage box 30 .

Therefore, according to one embodiment of the invention, the water pump 10 supplies the contaminated water containing microplastics to the storage box 30 through the supply pipe 20.

Then, while the contaminated water is located in the storage box 30 for a certain period of time, the microplastics are adsorbed to the hydrogel-treated coffee waste adsorbent.

Finally, purified water from which microplastics are removed is discharged through the drain pipe 40 .

Although the above has been described with reference to an embodiment of the present invention, those skilled in the art can make various modifications to the present invention within the scope not departing from the spirit and scope of the present invention described in the claims below. It will be appreciated that modifications and changes may be made.

10: water pump, 20: supply pipe
30: storage box 31: supply mesh
32: drain mesh 40: drain pipe

Claims (7)

Eluting the hydrophilic substance in the coffee waste by supporting the coffee waste in an organic solvent (S100);
Washing the coffee grounds from which the hydrophilic material is eluted (S200);
Irradiating UV rays to the washed coffee grounds and drying them (S300);
Mixing the dried coffee ground powder with hydrogel powder and then soaking in an aqueous solution of calcium chloride to treat the coffee grounds as a hydrogel (S400); and
Filtering the hydrogel-treated coffee grounds and then drying (S500); characterized in that it comprises
Manufacturing method of adsorbent for removing microplastics using coffee waste. According to claim 1,
Characterized in that the organic solvent is ethanol,
Manufacturing method of adsorbent for removing microplastics using coffee waste. According to claim 1,
Characterized in that the hydrogel powder is porous when solidified and a powder having swelling property is used
Manufacturing method of adsorbent for removing microplastics using coffee waste. According to claim 1,
The ultraviolet rays are characterized in that the wavelength range is 100nm to 300nm
Manufacturing method of adsorbent for removing microplastics using coffee waste. According to claim 1,
When mixing the hydrogel powder and the coffee ground powder, the mixing ratio is 0.16 to 0.5 in weight ratio of the hydrogel powder to the coffee ground powder.
Manufacturing method of adsorbent for removing microplastics using coffee waste. As an adsorbent for removing microplastics in an aqueous phase,
An adsorbent for removing microplastics using coffee waste prepared by the method according to any one of claims 1 to 5. A water pump that raises contaminated water containing microplastics; a supply pipe connected to the water pump to move contaminated water to a storage box; a storage box containing the adsorbent of claim 6 capable of adsorbing microplastics in the contaminated water while the contaminated water supplied from the supply pipe is stored; And a drain pipe for discharging purified water from which microplastics are removed from the contaminated water.
Adsorption system for removing microplastics using coffee waste.

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