KR20210089910A - Biosorbent for treating Cr(VI)-containing wastewater using coffee waste and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a biosorbent for treating wastewater containing hexavalent chromium using coffee waste and a manufacturing method thereof, and more specifically, to a biosorbent for treating wastewater containing hexavalent chromium using coffee grounds and a manufacturing method thereof, in which it is possible to manufacture the biosorbent without pretreatment by using the coffee waste which completed roasting, grinding and coffee-extraction, and thus, manufacturing cost is reduced and a manufacturing process is simple and a conventional expensive adsorbent or hexavalent chromium removal process can be replaced.

Description

Biosorbent for treating Cr(VI)-containing wastewater using coffee waste and manufacturing method thereof

The present invention relates to a biosorbent for treatment of hexavalent chromium-containing wastewater using coffee waste and a method for manufacturing the same, and specifically, it is eco-friendly, economical and eco-friendly by using coffee waste, which is biomass generated in large quantities in cafes, restaurants, etc. , It relates to a biosorbent for treating wastewater containing hexavalent chromium using coffee beans, which can replace the conventional expensive adsorbent or hexavalent chromium removal process, and a method for manufacturing the same.

As Korea's coffee consumption increases, the amount of coffee waste thrown away by coffee shops in Seoul is 140 tons per day on average, and the processing cost is 1.1 billion won per year. As of 2017, per capita coffee consumption was an average of 512 cups in Korea, with an average annual consumption of 26.5 billion cups of coffee in Korea, and an annual average of about 130,000 tons of coffee beans, a fairly large amount of coffee beans being thrown away as waste. However, looking at the recent research trend on coffee beans, it has been proven that 98% of coffee beans that are thrown away after coffee extraction are organic resources with high recycling value, so various ideas for the use of coffee beans are emerging. As an example, Korean Patent No. 10-1989874 “Cosmetic composition containing fermented coffee extract as an active ingredient”, Korean Patent No. 10-2022535 “Method for manufacturing coal briquettes containing coffee beans”, Korean registered patents No. 10-1801655 “Method for composting coffee beans and food waste by microbial fermentation and fermented compost produced by the method”, etc. are disclosed. In addition, 'Coffee Boil Clay', 'Coffee Boil Brick', 'Coffee It is recycled in various forms like 'Park Table'.

On the other hand, chromium may have an oxidation number of -2 to +6 in nature, but usually exists in the form of +3 and +6. While trivalent chromium is known as a trace element necessary for life, hexavalent chromium is regulated as a carcinogen because its strong oxidizing power can damage cell tissues or cause DNA mutation. In the US EPA, hexavalent chromium and total chromium The standard of effluent is stipulated to be less than 0.05ppm.

Currently, the most common treatment method for hexavalent chromium is chemically reducing hexavalent chromium to trivalent chromium using a reducing agent such as _{ferrous sulfate (FeSO 4 ) under acidic conditions, and then using slaked lime or caustic soda under alkaline conditions.} It is a method of neutralizing sedimentation, separating it into chemical sludge, and treating it as special waste. However, this treatment method does not satisfy the legal emission standards if the dilution effect is excluded from a technical point of view, and there is a problem that a large amount of chromium-containing sludge, another pollutant, is generated, the treatment cost of the sludge is required, and recycling is difficult. The problem is that it is almost impossible.

Accordingly, the inventors of the present invention have researched to develop a hexavalent chromium adsorbent that is economical and satisfies the legal emission standards for hexavalent chromium. As a result, a biosorbent was prepared using coffee grounds containing a large amount of electron donor groups such as polyphenols. The present invention was completed by confirming that the biosorbent was effective in removing hexavalent chromium and trivalent chromium without chemical input.

Korean Patent No. 10-1989874 Korean Patent Registration No. 10-2022535 Korean Patent No. 10-1801655

Hexavalent chromium using coffee waste which is eco-friendly and economical by recycling coffee waste, which is biomass generated in large quantities in cafes and restaurants of the present invention, and can replace the conventional expensive adsorbent or hexavalent chromium removal process To provide a biosorbent for treatment of containing wastewater and a method for manufacturing the same.

In addition, the biosorbent of the present invention and its manufacturing method can be manufactured only in the polymer material mixing step and crosslinking step without pre-treatment using coffee beans that have been ground and roasted and coffee extraction is completed, so the manufacturing process is lower than that of the conventional adsorbent. It is very simple and the manufacturing cost can be reduced.

In order to achieve the above object, the inventor of the present invention uses coffee waste, which is a biomass that is roasted and pulverized, coffee extraction is completed and does not require pretreatment such as crushing and heat treatment, 1) dried coffee grounds, A mixing step of mixing a polymer material having an anionic functional group and distilled water; 2) a crosslinking step of crosslinking by adding a crosslinking agent to the mixture of step 1); and 3) a separation and washing step of separating and washing the cross-linked mixture of step 2); provides a biosorbent for treatment of hexavalent chromium-containing wastewater using coffee beans prepared in step 2) and a method for preparing the same.

The manufacturing method of the biosorbent for hexavalent chromium-containing wastewater treatment using coffee waste of the present invention consists only of a polymer material mixing step and a crosslinking step in the coffee grounds that do not require pre-treatment as coffee extraction is completed, thereby reducing the manufacturing cost. and the process is simple.

In addition, the biosorbent using coffee beans prepared by the method of the present invention exhibits excellent hexavalent chromium removal effect when treated with hexavalent chromium-containing wastewater.

In addition, the biosorbent using coffee foil prepared by the method of the present invention is cross-linked with anionic polymer materials, so that not only hexavalent chromium but also trivalent chromium and other cationic metals can be simultaneously removed, and organic matter eluted from the coffee grounds is removed. can be reduced.

1 is a view showing the hexavalent chromium removal rate of coffee waste (coffee waste) according to pH.
2 is a diagram showing the effect of removing hexavalent chromium when continuously adding a solution of hexavalent chromium to the biosorbent using coffee foil of the present invention in the column process for 5 days.

Hereinafter, embodiments of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily carry out the present invention. The embodiments of the present invention are provided in order to more completely explain the present invention to those of ordinary skill in the art. Accordingly, the embodiment of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below.

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

As used throughout the specification of the present invention, the term “step of (to)” or “step of” does not mean “step for”.

The present invention provides a method for producing a biosorbent for treating hexavalent chromium-containing wastewater using coffee waste.

In the present invention, the biosorbent for treating wastewater containing hexavalent chromium is prepared by a method comprising the following steps.

1) a mixing step of preparing a mixture by mixing dried coffee foil, a polymer material having an anionic functional group, and distilled water;

2) a crosslinking step of preparing a crosslinked mixture by adding the mixture prepared through the mixing step of step 1) to a crosslinking agent; and

3) Separation and washing step of separating and washing the cross-linked mixture prepared through the cross-linking step of step 2).

In the present invention, coffee grounds are wastes generated in large quantities in cafes, restaurants, etc., and are roasted and ground coffee beans that have been extracted and are biomass that does not require pretreatment such as crushing and heat treatment. The component of the coffee foil is an organic polymer consisting of polysaccharides, polyphenols, etc. on the surface of a large amount of electrons (e ^- ) such as phenyl group, carboxyl group, carbonyl group and hydroxyl group. This is formed to show a strong reducing power and an excellent effect in removing hexavalent chromium metal.

In the present invention, the polymer material having an anionic functional group is alginate. The alginate is a granular material that can maintain a constant size of the material and increase mechanical strength, and can remove hexavalent chromium and trivalent chromium as well as other cationic metals contained in wastewater due to anionic functional groups. have.

In the present invention, the mixing step of step 1) may be prepared by mixing dried coffee foil, a polymer material having an anionic functional group, and distilled water. The polymer material having the anionic functional group may be prepared by mixing 10 to 500 parts by weight of the polymer material when the dried coffee leaf is 100 parts by weight, preferably 10 to 250 parts by weight of the polymer material, more preferably the polymer A mixture may be prepared by mixing 10 to 50 parts by weight of the material. In addition, distilled water may be prepared by mixing 500 to 2500 parts by weight of distilled water when the dried coffee beans are 100 parts by weight, preferably 1000 to 2500 parts by weight of distilled water, more preferably 1500 to 2500 parts by weight of distilled water. Mixtures can be prepared.

In the present invention, the crosslinking agent may be a mixture of calcium chloride, ferric chloride, sodium hydroxide and distilled water having a concentration of 0.1 to 2.0 M, preferably an aqueous calcium chloride solution having a concentration of 0.1 to 2.0 M, but is not limited thereto.

In the present invention, in the crosslinking step of step 2), 100 parts by weight of the mixture of step 1) may be added to 500 to 1000 parts by weight of a crosslinking agent to prepare a crosslinked mixture. In addition, the crosslinking step may be cross-linked for 1 to 30 hours, preferably 1 to 20 hours, more preferably 1 to 10 hours.

When the polymer material having an anionic functional group is crosslinked through the crosslinking step, the elution of organic carbon eluted from the coffee foil can be suppressed in the form of particles rather than powder because the ground coffee foil is fixed, and it becomes a constant shape. Recovery can be facilitated.

The crosslinking process of the mixture through the crosslinking step is shown in Schemes 1 and 2 below. Scheme 1 below is a formula showing a crosslinking reaction when alginate is used as a polymer material having an anionic functional group.

<Scheme 1>

(C ₆ H ₇ O ₆ Na) _2n + (CaCl ₂ ) _n → [(C ₆ H ₇ O ₆ ) ₂ Ca)] _n + (NaCl) _2n

Scheme 2 below is a formula showing a crosslinking reaction using chlorogenic acid, one of the types of polyphenols present in coffee grounds, as an example.

<Scheme 2>

In the crosslinking step, the shape of the mixture to be crosslinked may be determined according to the shape or diameter of the nozzle to be injected into the crosslinking agent. Depending on the input method, a crosslinked mixture having one shape selected from the group consisting of beads, rods, fibers, skeins and plates may be prepared. As the diameter of the crosslinked mixture decreases, the specific surface area increases, so that the removal effect of hexavalent chromium can be improved, but it is preferable to prepare the crosslinked mixture with a diameter of 1.5 to 4 mm in terms of the efficiency of the manufacturing process.

In the present invention, for the separation step in the separation and washing step of step 3), a sieving method among methods capable of separating the crosslinked mixture in the form of particles prepared through the crosslinking step of step 2) from the crosslinking agent may be used, but in particular It is not limited and any one can be used. The crosslinked mixture in the form of particles is advantageous for solid-liquid separation. The washing step is preferably repeated 4 to 6 times using distilled water, but is not limited thereto and is not particularly limited and any type may be used.

In addition, it is preferable to use the biosorbent for which the separation and washing steps have been completed, with a moisture content of 80% or more, and only the surface water is removed without going through a special drying process.

In addition, the present invention provides a biosorbent for treatment of wastewater containing hexavalent chromium using coffee grounds. The biosorbent can be removed by reducing hexavalent chromium, a toxic substance, to trivalent chromium, a non-toxic substance, by using a strong reducing power, and anionic polymer materials are crosslinked to ion exchange not only hexavalent chromium but also trivalent chromium and The scope of application can be expanded by removing other cationic contaminants.

The biosorbent may have one shape selected from the group consisting of beads, rods, fibers, skeins, and plates. In addition, as the diameter of the biosorbent increases, the surface area increases, so that the effect of removing hexavalent chromium, trivalent chromium and other cationic contaminants can be improved, but it is preferably 1.5 to 4 mm in diameter in terms of the efficiency of the manufacturing process. .

Hereinafter, the present invention will be described in more detail through Examples, Experimental Examples and Comparative Examples. However, the following Examples and Experimental Examples are intended to help the understanding of the present invention and are not intended to limit the scope of the present invention.

<Example 1> Coffee foil in powder form

The coffee leaves discarded in the cafe were collected and dried at a temperature of 100° C. for 24 hours to prepare coffee leaves in powder form.

<Example 2> Preparation of particle-form biosorbent using coffee foil

After collecting the discarded coffee beans and drying them at 100° C. for 24 hours, 100 parts by weight of coffee leaves, 20 parts by weight of alginate having an anionic functional group, and 1500 parts by weight of distilled water were mixed to prepare a coffee mixture mixture. After adding 1000 parts by weight of a 0.1M aqueous calcium chloride solution as a crosslinking agent to 100 parts by weight of the mixture, the crosslinking reaction was carried out for 10 hours. After the crosslinking reaction was completed, the mixture converted into a skein type was sieved to separate from the crosslinking agent, washed with distilled water 5 times, and moisture was removed from the surface to prepare a biosorbent using coffee leaves.

<Experimental Example 1> Evaluation of hexavalent chromium removal performance of particle-type biosorbent using coffee foil

The evaluation of the hexavalent chromium removal performance of the coffee foil prepared in <Example 1> was performed. In this case, the standard reagents used in the experimental example are shown in Table 1 below.

Sample name chemical formula Molecular Weight Potassium dichromate K ₂ Cr ₂ O ₇ 294.18

<1-1> Evaluation of Hexavalent Chromium Removal Performance by pH of Coffee Foil

5 g/L of the coffee beans prepared in <Example 1> were respectively added to three stirring devices into which wastewater having a concentration of hexavalent chromium was 50 mg/L, and the pH was set and maintained at 2, 3 and 4. Then, the mixture was stirred for 8 hours at a speed of 200 rpm at room temperature. After stirring, the wastewater was filtered and the concentration of hexavalent chromium remaining in the wastewater was measured using a spectrophotometer (Optizen 1412V, Mecasys Co., Ltd., Korea) (FIG. 1).

As a result, it was confirmed that the lower the pH, the shorter the hexavalent chromium removal time of the biosorbent using the coffee foil of the present invention.

<1-2> Evaluation of hexavalent chromium removal performance in continuous process of biosorbent using coffee leaf

After adding 3 g of the coffee beans prepared in <Example 2> to a column having a volume of 50 ml, 20 mg/L of a hexavalent chromium solution (pH 2) was added at a flow rate of 50 ml/h for 5 days. . After the column process, the wastewater was filtered and the concentration of hexavalent chromium remaining in the wastewater was measured using a spectrophotometer (Optizen 1412V, Mecasys Co., Ltd., Korea) (FIG. 2).

As a result, it was confirmed that the amount of hexavalent chromium treated per 1 g of coffee beans for 5 days was about 114 mg/g, and it was confirmed that the biosorbent using coffee beans of the present invention can remove hexavalent chromium for a long period of time. .

<Comparative Example 1> Evaluation of hexavalent chromium removal performance of biosorbents using coffee leaves and coffee leaves

Total chromium (hexavalent chromium + trivalent chromium) removal and TOC (Total Organic Carbon) elution amount of particle-type biosorbent using coffee powder in powder form of <Example 1> and coffee foil prepared in <Example 2> was measured (Table 2).

Measurement of total chromium removal: After adding 5 g/L of coffee grounds to a stirring device in which wastewater having a concentration of hexavalent chromium of 50 mg/L is added and stirring at 200 rpm for 8 hours, the amount of total chromium remaining after filter treatment The concentration was measured. Total chromium is measured after all hexavalent chromium is removed, and the measured total chromium value is the same as trivalent chromium remaining in the solution.

Measurement of TOC elution amount: 5 g/L of coffee grounds were added to a stirring device in which wastewater having a concentration of hexavalent chromium of 50 mg/L was added, stirred at 200 rpm for 8 hours, filtered, and the TOC of the remaining solution was filtered. The concentration was measured.

division Total Cr (mg/L) Total Organic Carbon (mg/L-C) <Example 1> 9.812 248.0 <Example 2> 1.533 31.88

As a result, it was confirmed that the biosorbent using coffee foil prepared in <Example 2> was significantly superior in the removal effect of total chromium compared to coffee foil, and the amount of dissolution of TOC was significantly reduced.

In conclusion, as a result of confirming the hexavalent chromium removal effect of the biosorbent prepared by recycling coffee grounds, which is biomass generated in large quantities in cafes and restaurants of the present invention, the lower the pH, the better the removal effect and can be used for a long time. Confirmed.

In addition, it was confirmed that the biosorbent of the present invention prepared by mixing coffee foil, alginate and distilled water was superior in total chrome removal and TOC dissolution effect than in the case of using only coffee foil.

Claims (12)

1) a mixing step of preparing a mixture by mixing dried coffee foil, a polymer material having an anionic functional group, and distilled water;
2) a crosslinking step of preparing a crosslinked mixture by adding the mixture prepared through the mixing step of step 1) to a crosslinking agent; and
3) a separation and washing step of separating and washing the crosslinked mixture prepared through the crosslinking step of step 2);
A method for producing a biosorbent for treatment of hexavalent chromium-containing wastewater using coffee leaves, comprising a.
According to claim 1,
The coffee foil is a waste that has been ground and roasted to complete coffee extraction, and is a coffee foil that does not require pretreatment, a method for producing a biosorbent for treatment of wastewater containing hexavalent chromium.
According to claim 1,
The polymer material having an anionic functional group is alginate, a method for producing a biosorbent for treating wastewater containing hexavalent chromium.
According to claim 1,
The step 1) is a step of preparing a mixture by mixing 100 parts by weight of coffee leaves, 10 to 500 parts by weight of a polymer material having an anionic functional group, and 500 to 2500 parts by weight of distilled water, a method for preparing a biosorbent for treating wastewater containing hexavalent chromium .
According to claim 1,
The step 1) is a step of preparing a mixture by mixing 100 parts by weight of coffee grounds, 10 to 250 parts by weight of a polymer material having an anionic functional group, and 1000 to 2500 parts by weight of distilled water, a method for preparing a biosorbent for treating wastewater containing hexavalent chromium .

According to claim 1,
The step 1) is a step of preparing a mixture by mixing 100 parts by weight of coffee grounds, 10 to 50 parts by weight of a polymer material having an anionic functional group, and 1500 to 2500 parts by weight of distilled water, a method for preparing a biosorbent for treating wastewater containing hexavalent chromium .
According to claim 1,
The crosslinking agent is 0.1 to 2.0 M calcium chloride, hexavalent chromium-containing biosorbent manufacturing method for wastewater treatment.
According to claim 1,
Step 2) is a step of preparing a crosslinked mixture by adding 500 to 1000 parts by weight of a crosslinking agent to 100 parts by weight of the mixture of step 1) to prepare a crosslinked mixture, a method for producing a biosorbent for treating wastewater containing hexavalent chromium.
According to claim 1,
Step 2) is a method for producing a biosorbent for treatment of wastewater containing hexavalent chromium, in which the crosslinking is carried out for 1 to 10 hours.
10. A biosorbent for treatment of wastewater containing hexavalent chromium using coffee foil prepared by the method according to any one of claims 1 to 9.
11. The method of claim 10,
The biosorbent has one shape selected from the group consisting of beads, rods, fibers, skeins and plates, biosorbent for treatment of hexavalent chromium-containing wastewater.
11. The method of claim 10,
The biosorbent has a diameter of 1.5 to 4 millimeters, a biosorbent for treating wastewater containing hexavalent chromium.

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