KR102529667B1 - The composition for electrodes for enzymatic fuel cells comprising sugar extracted from using algae - Google Patents

Abstract

The present invention relates to a composition for an enzyme fuel cell containing sugar extracted from algae.

Description

Composition for enzymatic fuel cells comprising sugar extracted from algae {The composition for electrodes for enzymatic fuel cells comprising sugar extracted from using algae}

The present invention relates to a method for effectively extracting sugar from algae and applying it to an enzyme fuel cell system to generate electricity.

Due to the environmental damage caused by the indiscriminate use of fossil fuels and the unavoidable depletion of fossil fuels, research for the development of new and renewable energy is urgently needed worldwide. Bioenergy is attracting attention worldwide because it is renewable and has positive effects such as securing alternative energy, improving the environment, and generating income for farmers who grow raw materials. In particular, the development of technologies for producing energy using marine biomass, which is the third generation, has recently been actively pursued. Among them, there are various species of algae all over the world in various forms, from unicellular to multicellular, and recently, they are attracting attention as a next-generation biomass for future energy production along with CO2 reduction effects. In particular, Chlorella, a green algae that grows wild all over the world, has a fast growth rate, high photosynthetic efficiency, and high content of intracellular lipid components and polysaccharides, so it is more energy-efficient than first- and second-generation biomass such as grains and wood. Based on the advantage of high efficiency, it is attracting attention as a third-generation biomass (marine biomass). In particular, the cell wall structure of microalgae is composed of two layers, an outer cell wall layer and an inner cell wall layer, and the outer cell wall layer is composed of a trilaminar structure containing cellulose. Since the structure of the cell wall is very hard, it is difficult to convert to glucose without going through a physical and chemical pretreatment process. Therefore, in order to convert polysaccharide components such as cellulose and starch into monosaccharides, a pretreatment process for crushing hard cell walls should be preferentially performed.

Glucose produced from algae can take a large part in the manufacture of glucose biosensors, which are attracting worldwide attention as next-generation clean energy conversion devices that have recently been rapidly improved. The total market size of the world biosensor was $ 6.57 billion in 2002, and this size is about $ 8.2 billion in 2004 with an average annual growth rate of 11.6%. Among them, the food biosensor market accounted for about 12.7% of the total biosensor market, worth about 140 million dollars. Currently, developed countries are making various efforts to quickly detect contamination and carry out protection/preservation measures using various detection technologies for environmental protection, and many companies are preparing to lead the world market by researching related sensors and reagents. Recently, studies have been attempted to directly convert discarded or inedible biomass into electrical energy, and one representative example is an enzyme fuel cell. Biofuel cells such as enzyme fuel cells are attracting attention because they are safe, have a low environmental load, and have the advantage of using recyclable biomass as an energy source. However, when such biomass energy is applied to an enzyme fuel cell system, it is not yet possible to obtain sufficient power for practical use. On the other hand, US Patent Publication No. 2014/0004427 discloses a biomass processing method that can be used in a fuel cell, but still has a problem of low power when applied to an enzyme fuel cell system.

An object of the present invention is to establish optimal acid extraction conditions for extracting sugars contained in algae, and apply them to an enzyme fuel cell system to generate electricity. Accordingly, the present inventors have completed the present invention by developing a technology for generating high power using algal sugar.

US Patent Publication 2014/0004427

An object of the present invention is to provide a composition for an enzyme fuel cell that effectively extracts sugars contained in algae and applies it to an enzyme fuel cell system to solve the problem of existing low power, an enzyme fuel cell using the same, and a method related thereto. .

The present invention provides a composition for an enzyme fuel cell that effectively extracts sugars contained in algae and applies it to an enzyme fuel cell system to solve the existing low power problem, and an enzyme fuel cell using the same, and a method related thereto.

The present invention effectively extracts sugars contained in algae and applies them to an enzyme fuel cell system to provide a composition for an enzyme fuel cell and an enzyme fuel cell having a very high power density, thereby contributing to environmental and energy problems. there is.

1 is a graph showing the optimal conditions for extraction sugar using the acids selected in Table 2. Figure 1a shows the acid concentration, Figure 1b shows the results according to the high / liquid ratio.
2 is a graph showing power density measured by applying sugars extracted from algae to an enzyme fuel cell system. 2a is a power density measurement result using extracted sugar, and FIG. 2b is a power density measurement result of extracted sugar from which salt is removed.

The present invention relates to a composition for extracting sugar contained in algae and applying it to an enzyme fuel cell system to generate electricity and a method related thereto.

Specifically, the present invention provides a composition for an enzyme fuel cell containing sugar extracted from algae, a method for extracting sugar from algae for use as a substrate for an enzyme fuel cell, and a composition or an enzyme fuel cell containing the sugar as a substrate it is about The present inventors have experimentally demonstrated that when sugar extracted from algae is used in an enzyme fuel cell, the power density of the existing enzyme fuel cell can be increased by more than 5 times, thereby solving the problem of low power of the conventional enzyme fuel cell. The invention was completed.

In the present invention, the algae is not particularly limited as long as it is glucose-containing algae, and may be one or more of green algae, red algae, and brown algae. Specifically, the alga is Chlorella Pyrenoidosa ( Chlorella pyrenoidosa ), Chlorella vulgaris ( Chlorella vulgaris ) and Nannochloropsis Gaditana ( Nannochloropsis gaditana ), Nannochloropsis gaditana ( Nannochloropsis gaditana ) is preferred.

Specifically, the sugar may be glucose. The sugar may be used as a substrate for an enzyme in an enzyme fuel cell, and the enzyme fuel cell refers to a cell using an enzyme as a catalyst of a fuel cell. In the present invention, an enzyme using a catalyst using sugar as a substrate As long as it is a fuel cell, it is applicable without particular limitation.

The method of extracting sugar for use as a substrate for an enzyme fuel cell from algae of the present invention is to treat the algae with an acid at a concentration of 2 to 4% so that the algae and acid have a solid-liquid ratio of 80 to 140 g / L. to be characterized It was experimentally confirmed that the sugar extraction efficiency was maximized when the acid in the above range was treated. If the acid concentration of 4% or more is used, sugar is overly decomposed and the concentration of sugar extraction is reduced.

The acid may be one or more of sulfuric acid, hydrochloric acid, phosphoric acid, peracetic acid and nitric acid, but is not limited thereto. Preferably, hydrochloric acid can be used. It was experimentally confirmed that the sugar extraction efficiency was maximized when the hydrochloric acid was treated. It is almost completely ionized in an aqueous solution such as hydrochloric acid, nitric acid, sulfuric acid, etc., which are aqueous solutions of hydrogen chloride, and it is easy to produce hydrogen ions, so it shows good hydrolysis efficiency. Among them, hydrolysis acid has the highest ionization constant compared to other acids. preferred as

The present invention relates to an enzyme fuel cell comprising, as a substrate, the sugar extracted from algae by the above composition or the above method. The enzyme fuel cell using the composition or sugar as a substrate of the present invention exhibits greatly improved power density.

The enzyme fuel cell of the present invention may be manufactured by applying a conventional technology related to an enzyme fuel cell, except that sugar extracted from algae or a composition containing the same is included as a substrate. Specifically, the enzyme fuel cell of the present invention may further include an electrode including an enzyme for an oxidation reaction or an enzyme for a reduction reaction with respect to the substrate.

Hereinafter, the present invention will be described in more detail by the following examples. However, these are only for exemplifying the present invention, and the scope of the present invention is not limited by these examples.

reference example

(a) Component analysis experiment according to algae type

Table 1 shows three species of algae, Chlorella Pyrenoidosa ( Chlorella pyrenoidosa ), Chlorella vulgaris ( Chlorella vulgaris ), Nannochloropsis gaditana (Carbohydrate), fiber (Fiber), protein (Protein), lipid (Lipid), and ash (Ash) components are measured.

C. pyrenoidosa C. vulgaris N. gaditana carbohydrate (%) 9.94 10.97 11.01 fiber (%) 0.64 0.57 1.15 protein (%) 56.61 55.79 56.41 Lipid (%) 4.55 6.34 5.13 Ash etc. (%) 7.86 7.84 5.74

As shown in Table 1, three species of algae, Chlorella pyrenoidosa ( Chlorella pyrenoidosa ), Chlorella vulgaris ( Chlorella vulgaris ) and Nannochloropsis gaditana were selected, and for component analysis, carbohydrates (Carbohydrate), fiber (Fiber), protein (Protein), lipid (Lipid), ash ( Ash) and other components were measured. As a result, Nannochloropsis garditana contained about 10% sugar, of which glucose accounted for about 50%.

(b) Extraction of algae-containing sugars using various acids

Sugars contained in algae were extracted using various acids. Specifically, Table 2 is a table for extracting sugar from algae using the five acids of the present invention.

Acid concentration (%) sulfuric acid peracetic acid phosphoric acid Hydrochloric acid nitric acid Sugar concentration (g/L) efficiency (%) Sugar concentration (g/L) efficiency (%) Sugar concentration (g/L) efficiency (%) Sugar concentration (g/L) efficiency (%) Sugar concentration (g/L) efficiency (%) One 0.94±0.06 9.45 0.34±0.01 3.47 0.46±0.01 4.68 7.12±0.01 71.62 1.19±0.05 11.96 2 2.84±0.01 28.57 0.46±0.03 4.62 0.68±0.01 6.85 9.53±0.01 95.88 6.37±0.08 64.07 3 5.73±0.01 57.64 0.55±0.01 5.58 0.90±0.01 9.06 8.96±0.11 90.12 8.06±0.73 81.07 4 7.00±0.17 70.40 0.59±0.01 5.92 1.11±0.01 11.13 9.14±0.06 91.98 8.72±0.31 87.70

Referring to Table 2, the acids and concentrations extracted under the conditions of high / liquid ratio 100 g / L, 121, 15 min using 5 acids (sulfuric acid, hydrochloric acid, phosphoric acid, peracetic acid, nitric acid) of 1 to 4% were shown. . As a result, the extraction efficiency showed different results for all five acids. In the case of sulfuric acid and nitric acid, as the acid concentration increased from 1% to 4%, the extraction efficiency tended to be 9.45 ~ 70.40% and 11.96 ~ 87.70%, respectively. However, peracetic acid and phosphoric acid showed low hydrolysis efficiencies of less than 20% and were not suitable as extraction acids. In the case of hydrochloric acid, the extraction efficiency was 95.88% at a concentration of 2%. It is almost completely ionized in aqueous solutions such as hydrochloric acid, nitric acid, sulfuric acid, etc., which are aqueous solutions of hydrogen chloride, and it is easy to produce hydrogen ions, so the extraction efficiency is good. Among them, hydrochloric acid has the highest ionization constant compared to other acids, so it is suitable as an acid with high extraction efficiency.

Example 1. Optimization of sugar extraction using the selected optimal acid

Sugar extraction optimization (acid concentration, high/liquid ratio) was performed using the optimal acid selected above. Specifically, in order to set the optimal conditions for acid extraction, the high/liquid ratio was 20 to 140 g/L and the acid concentration range was set to 0.5 to 10% in a 20 mL vial. The acid concentration was prepared according to the specific gravity suitable for the concentration using a hydrometer. The heat treatment time was treated for 121, 15 minutes in a sterilizer. After acid hydrolysis, it was neutralized to pH 7 using 50% NaOH. The neutralized sample was centrifuged at 12,000 rpm for 10 minutes, and glucose was analyzed in the separated supernatant using liquid chromatography. The efficiency (%) of acid extraction can be expressed by the following formula.

Formula: acid extraction efficiency (%) = concentration per extraction / total carbohydrates × 100

Referring to Figure 1a, in order to measure the amount of sugar extracted at various concentrations using selected hydrochloric acid, acid extraction was performed at a concentration of 0.5 to 10%, and the most effective result was when the amount of sugar extracted from 2 to 10% was 2% showed After 2%, the concentration of hydrochloric acid was strong, so the sugar was overly decomposed, and rather, the efficiency was reduced. In addition, referring to Figure 1b, which is the result of acid extraction from 20 to 140 g / L by varying the ratio of algae and hydrochloric acid, the amount of extracted sugar increased as much as the excess algae was used, but the efficiency did not increase. Therefore, acid extraction at a high/liquid ratio of 100 g/L was selected as the optimal ratio.

Example 2. Manufacturing of enzyme fuel cell system

The extracted sugar was applied to the enzyme fuel cell system. Enzymatic fuel cell system of the prior art is improved (contents of improvement: oxidation treatment method of graphite to effectively immobilize oxidation and reductase enzymes, optimization of the concentration of substances entering immobilization, use of algae extract sugar (glucose 0.5%)) to increase power Measured. Specifically, for immobilization of the enzyme, graphite was oxidized for 24 hours by putting 200 ml of sulfuric acid and phosphoric acid in a volume ratio of 9:1, 4 g of graphite, and 24 g of potassium permanganate as an oxidizing agent in a glass jacket at 4 °C. It activated the -OH group more effectively than the existing oxidation process, helping to modify the functional group required for enzyme immobilization. In addition, about 0.5% of algae extract sugar extracted according to Example 1 was used instead of a 1% glucose solution conventionally used as a substrate.

Experimental Example 1. Power density measurement using an enzyme fuel cell system

The electrode on which glucose oxidase is immobilized on the graphite composite prepared in Example 2 is used as an anode and the electrode on which Lacase reductase is immobilized is used as a cathode, and connected to each other using 0.05M phosphate buffer (pH 7.0), a basic enzyme fuel cell was fabricated using the electrolyte containing 0.5% glucose extracted according to Example 1 above. Then, the enzyme fuel cell was connected to the VersaSTAT 3 device (AMETEK, Princeton Applied Research, USA), and the power density was measured at 25 °C.

As a result of the above experiment, the enzyme fuel cell using glucose extracted from algae according to the present invention showed a maximum power density of 2694 uW/cm2. (See Figure 2a)

This is about 5 times higher than the maximum power density of about 500 uW/cm2 obtained in the prior art power generation using sugar, as shown in Table 3 below. In particular, 1% glucose used as a substrate in prior literature It is significant that the power density increased about 5 times with half the concentration.

As such, in the present invention, the reason for the rapid increase in power density is that salt (NaCl) is generated while sugar extracted with hydrochloric acid (HCL) is neutralized with sodium hydroxide (NaOH), and the salt generated here is ionized in a polar solvent while serving as an electrolyte. It seems to show the synergistic effect of the enzyme fuel cell system while conducting electricity.

Figure 2b is the result of measuring the power density by removing the generated salt with an ion exchange resin filter while neutralizing, and showed a power density of 1815 uW/cm2. Compared to FIG. 2A , it can be seen that the power density is reduced because the electrolyte is removed, but even in this case, the power density is three times or more significantly higher than that of the prior art.

Claims (9)

It contains sugar extracted by acid treatment of algae,
The acid treatment is a composition for an enzyme fuel cell in which the algae are treated with an acid at a concentration of 2 to 4% so that the solid-liquid ratio of the algae and the acid is 80 to 100 g / L.
The composition according to claim 1, wherein the algae is at least one of glucose-containing green algae, red algae, and brown algae.
The composition according to claim 1, wherein the sugar is glucose.
The composition of claim 1, wherein the sugar is used as a substrate for an enzyme in an enzyme fuel cell.
A method of extracting sugar for use as a substrate for an enzyme fuel cell from algae, wherein the algae is treated with an acid at a concentration of 2 to 4% so that the solid-liquid ratio of the algae and acid is 80 to 100 g / L. .
The method according to claim 5, wherein the algae is at least one of glucose-containing green algae, red algae, and brown algae.
6. The method of claim 5, wherein the sugar is glucose.
An enzyme fuel cell comprising the composition of any one of claims 1 to 4 as a substrate.
The enzyme fuel cell of claim 8 , further comprising an electrode including an enzyme for an oxidation reaction or an enzyme for a reduction reaction with respect to the substrate.

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