KR101308913B1 - Method for cleaning of waste water using polydopamine - Google Patents

Abstract

The present invention relates to a wastewater purification method or a pollutant adsorption method using the adsorptive power of polydopamine, and more particularly to manufacturing silica beads coated with polydopamine, and using the same to be contained in a target containing contaminants such as wastewater. Wastewater purification or pollutant adsorption method for removing contaminants such as heavy metals, organic toxic substances and radioactive isotopes, and treating the silica beads with acid or hydrogen peroxide for reuse. It relates to a production method, polydopamine silica beads produced by the production method and the use of the silica beads. The present invention does not require a pretreatment process for wastewater purification, the process of preparing the filter is relatively simple, the production of oil and minerals in an aqueous solution is simple, and the regeneration of the filter is possible. Solve the problem of pollution.

Description

Method for cleaning wastewater using polydopamine {Method for cleaning of waste water using polydopamine}

The present invention relates to a wastewater purification method or a pollutant adsorption method using the adsorptive power of polydopamine, and more particularly to manufacturing silica beads coated with polydopamine, and using the same to be contained in a target containing contaminants such as wastewater. Wastewater purification or pollutant adsorption method for removing contaminants such as heavy metals, organic toxic substances and radioactive isotopes, and treating the silica beads with acid or hydrogen peroxide for reuse. It relates to a production method, polydopamine silica beads produced by the production method and the use of the silica beads.

Sustained population growth, rapid industrialization, and water shortages due to climate change are becoming increasingly serious, and efforts to resolve them are increasing rapidly. In this context, wastewater purification techniques are needed to address water shortages within limited water resources.

In particular, adsorption treatment has been widely used as a method of removing various heavy metals and organic substances from wastewater. Activated carbon with a porous structure is used as a material to effectively adsorb contaminants using a large surface area, and the rich carboxyl groups of alginate chelate heavy metals. However, activated carbon requires activation for adsorption, and alginic acid also needs to be immobilized on the surface in order to be used as an adsorbent. Therefore, the energy consumption increases with the increase of the process step, there is also a disadvantage in that the amount of adsorption is low or limited to some heavy metals in terms of efficiency. In addition, the treatment of adsorbents with contaminants adsorbed due to non-reusability or difficulty makes secondary pollution, which is directly related to waste of resources and cost. At present, efforts are being made to develop a low energy, high efficiency wastewater purification system by developing a new adsorption technology that solves these problems.

Therefore, next-generation adsorbents should (1) be able to effectively remove various organic / inorganic contaminants, (2) the manufacturing process of the adsorbents should be easy, and there should be no other pollution such as the use of organic solvents in the manufacturing process, and (3) It should be easy to reprocess the adsorbed material to prevent secondary contamination.

Accordingly, the present inventors can effectively remove various organic / inorganic contaminants, facilitate the manufacturing process of the adsorbent, do not have another contamination such as the use of organic solvent in the manufacturing process, and easily reprocess the adsorbed material. While studying the adsorption material that can prevent the, while finding that polydopamine can perform this function was completed the present invention.

It is therefore an object of the present invention to provide a new method for the purification of waste water or adsorption of contaminants with polydopamine.

In order to achieve the above object, the present invention comprises the steps of coating a polydopamine on a substrate; And it provides a wastewater purification method comprising the step of adsorbing the pollutant by introducing the substrate coated with polydopamine into the wastewater.

In order to achieve another object of the present invention, the present invention comprises the steps of mixing and stirring silica beads in a solution in which the dopamine hydrochloride salt is dissolved in a tris buffer of pH 8.0 to 9.0; Centrifuging the solution to remove excess polydopamine; And it provides a method for producing wastewater purification polydopamine silica beads comprising the step of freeze-drying the silica beads.

In order to achieve another object of the present invention, the present invention provides a wastewater purification polydopamine silica beads prepared by the above production method.

In order to achieve another object of the present invention, the present invention provides a composition for purification of wastewater comprising silica beads coated with polydopamine as an active ingredient.

In order to achieve another object of the present invention, the present invention comprises the steps of coating polydopamine on silica beads; And contacting the polydopamine-coated silica beads with a contaminant to adsorb the contaminant.

In order to achieve another object of the present invention, the present invention provides a composition for adsorbing contaminants comprising silica beads coated with polydopamine as an active ingredient.

Hereinafter, the present invention will be described in detail.

Polydopamine is a polymer that can reproduce the adhesive properties of mussels and can be easily mass-produced. Polydopamine is dissolved in water and coated on almost all substrates including heavy metals, semiconductors, heavy metal oxides, synthetic polymers, and ceramics in a very simple manner, and forms polymer films with a thickness of several nm to 50 nm depending on the coating time. The polydopamine film thus formed has been shown to show a high affinity for metal ions, and can be effectively coated with copper, gold, silver, and the like with only a few reducing agents. In addition, various organic substances can be immobilized through covalent bonds, and thus immobilized surface PEGylation, hyaluronic acid, and proteins to be used in many fields such as biochips, surface antimicrobial treatment, and nanoparticle surface modification. It is applied.

The present invention comprises the steps of coating a polydopamine on a substrate; And it relates to a wastewater purification method comprising the step of adsorbing contaminants by injecting the polydopamine-coated substrate wastewater.

This is explained in each step as follows.

Step (a) is the step of coating the polydopamine on the substrate.

In the present invention, the term "substrate" means a material that can be used as a filter for wastewater purification by coating polydopamine.

Since polydopamine has excellent surface coating ability on any substrate, various substrates can be used. Although not limited thereto, the substrate capable of coating the polydopamine may include silica beads, a liquid permeable film, a non-oxide metal including Au, Ag, Pt, Pd, TiO ₂ , SiO ₂ , Al ₂ O ₃ , Nb ₂ Metal oxides containing O ₅ , all alkali metals including Ca, K, Be, Sr, polystyrene, polyethylene, polycarbonate, polyethyleneterephthalate, polytetrafluoroethylene ( synthetic polymers including polytetrafluoroethylene, polydimethylsiloxane, polyetheretherketone, polyurethanes, glass, ceramics including hydroxyapatite, GaAs, Si ₃ N ₄ It may be a semiconductor including a particle or particles of various sizes not included in the material, preferably silica beads.

In one embodiment of the present invention, a silica microbead having a diameter of 40 to 60 μm, which is advantageous for adsorption due to a large surface area per unit volume, was used as a substrate. Polydopamine silica beads in this step is not limited thereto, but may be prepared according to the following method.

First, silica beads are mixed and stirred in a solution in which dopamine hydrochloride is dissolved in a tris buffer of pH 8.0 to 9.0. The silica beads are not limited thereto, but preferably 40 to 60 μm. The reaction time is not limited to this, but is stirred for 1 to 5 hours, preferably 2 to 4 hours.

Subsequently, the dopamine hydrochloric acid solution containing the silica beads is centrifuged to remove excess polydopamine. It is a process for removing excess polydopamine which is not coated on silica beads, and is repeatedly performed until the color of the supernatant becomes transparent.

Finally, the polydopamine silica beads were lyophilized to prepare polydopamine silica beads.

Step (b) is a step of adsorbing the contaminants by adding the polydopamine-coated substrate to the wastewater.

In this step, polydopamine has an excellent immobilization ability for heavy metal ions, organic toxic substances and radioactive isotopes, so that polydopamine-coated silica beads are added to the wastewater contaminated with the material to adsorb contaminants. It includes. The contaminant may be included without limitation so long as it is a material capable of forming a bond with polydopamine.

Thus, but not limited to, the heavy metals in the contaminants are Cr, Pb, Cd, Hg, Cu, Zn, Co, Ni, Mg, Fe, Mn or Ca, preferably Cr, which are known to interact with polydopamine , Pb, Cd, Hg or Cu, the organic toxic substances 4-AMP (4-aminopyridine), 4-MBT (4-methylbenzenethiol), amitrol (amitrole), starlicide, dichloran ( dicloran, aminopyralid, butylamine, proxan, quinoclamine, thiosemicarbazide, fluoroacetamide, tioclorim Or carbathion, preferably 4-aminopyridine (4-AMP), 4-methylbenzenethiol (4-MBT), and the radioisotope may be ¹⁷⁷ Lu or ⁹⁰ Y.

Among the contaminants, heavy metals refer to a collection of elements having a atomic mass of 63.546 to 200.590 between copper and lead in the periodic table and having a specific gravity of 4.5 or more. It tends to form and accumulate in the body rather than excreted outside the organism. It is reported that cadmium, lead, and mercury, which are representative harmful heavy metals, have high affinity to phosphate groups, proteins, nucleic acids, etc., and change the action of enzymes and inhibit the oxidation-phosphorylation process, which is essential for structural change and energy metabolism of nucleic acids. There is a bar.

In order to determine the mechanism of the polydopamine adsorbed on the heavy metal, XPS analysis of the binding of the polydopamine and copper (Cu) atoms was performed in one embodiment of the present invention. As a result, it was found that the heavy metal ion coordinated to the oxygen atom of the catechol group of polydopamine, resulting in a low electron-density of the carbon-oxygen bond, resulting in a high binding energy. In FIG. 3, the shape of the metal atom which coordinated with the oxygen atom of the catechol group of polydopamine is shown.

As a toxic organic substance, 4-AMP (4-aminopyridine) is a component of the insecticide, a dangerous substance that can disturb the central nervous system of mammals. 4-MBT (4-methylbenzenethiol) also enters the blood vessels when cyanosis, Oxygen deficiency causes blood to turn blue) and is a toxic substance that can cause inflammation of the digestive and respiratory tracts.

As a radioactive isotope, ¹⁷⁷ Lu (Lutetium) is a lanthanide-based radioactive metal used for radiotherapy or angiography, which inevitably remains in vials when administered in hospitals. In addition, ⁹⁰ Y (Yttrium), which forms a divalent ion similar to ¹⁷⁷ Lu, is a rare earth element and is used to generate a red laser.

On the other hand, the present invention comprises the steps of coating polydopamine on silica beads; And adsorbing the polydopamine-coated silica beads with the contaminant to adsorb the contaminant. Coating and contaminant contact / adsorption of polydopamine are as described above.

In the embodiment of the present invention, the experiment was carried out to determine whether the adsorption of the heavy metal, organic toxic substances and radioisotopes and polydopamine.

As a result, heavy metals showed significantly higher adsorption power than activated carbon, which is widely used as a conventional adsorbent, and in the case of organic toxic substances, organic toxicity was obtained from the absorbance measured before and after polydopamine silica bead treatment. Absorption in the ultraviolet region corresponding to 4-AMP and 4-MBT, which is a substance, was not observed, indicating that the organic toxic substance was removed from the wastewater. In addition, in the case of radioactive isotope ¹⁷⁷ Lu, after the polydopamine treatment, there is a difference according to the intensity of radioactivity, in all cases the radioactivity is reduced by more than 95% to confirm the adsorption capacity of polydopamine to the radioactive element.

In addition, the present invention relates to a wastewater purification method further comprising the step of treating acid, base or hydrogen peroxide to enable reuse of contaminant-adsorbed polydopamine silica beads in addition to the steps (a) and (b).

One of the important things in the purification of waste water is the treatment of adsorbents with adsorbed contaminants. This is because there is a risk of secondary contamination when treating the used filter, and problems such as cost and resource waste due to one-time use may occur. In order to solve this problem, the present invention includes a method of regenerating polydopamine silica beads adsorbed contaminants.

The method for regenerating the polydopamine silica beads is to treat polydopamine silica beads in which contaminants are adsorbed with an acid, a base, or hydrogen peroxide. During acid treatment, the concentration of hydrogen ions increases and the O-groups of polydopamine chelate metals to protonate to form the -OH form, leaving them in a form that can no longer interact with the metal. do. By this action, it is possible to remove contaminants adsorbed on the polydopamine beads during the acid treatment without limiting the type of acid. The type of the acid is not limited thereto, but the acid may be acetic acid, hydrochloric acid, sulfuric acid, nitric acid, carbonic acid, phosphoric acid, hydroiodic acid, hydrobromic acid, chromic acid, boric acid, hydrofluoric acid, or perchloric acid, and preferably acetic acid. .

In an embodiment of the present invention, contaminants were removed from polydopamine silica beads using acetic acid and hydrogen peroxide. As shown in FIG. 9, when polydopamine silica beads are treated with acetic acid, only adsorbed contaminants are selectively removed, and the polydopamine coating remains on silica beads, but when treated with hydrogen peroxide, polydopamine is adsorbed. Is removed.

In addition, bases may be treated in addition to acids and hydrogen peroxide to remove contaminants from polydopamine silica beads. Base treatment is a method used to wash metals in semiconductor processes and can be used to strip off coatings of polydopamine. Thus, upon base treatment, the polydopamine coating, along with the contaminants, can be removed from the silica beads. The base may be, but is not limited to, sodium hydroxide, calcium hydroxide, potassium hydroxide, ammonium hydroxide, barium hydroxide, cesium hydroxide, strontium hydroxide, lithium hydroxide or rubidium hydroxide.

On the other hand,

(a) mixing and stirring silica beads in a solution in which dopamine hydrochloride salt is dissolved in a tris buffer having a pH of 8.0 to 9.0;

(b) centrifuging the solution of step (a) to remove excess polydopamine; And

(C) provides a method for producing a polydopamine silica beads comprising the step of freeze drying the silica beads passed through the step (b).

In addition, the present invention provides a polydopamine silica bead prepared by the above production method.

Since the silica beads coated with the polydopamine of the present invention have excellent adsorptivity to contaminants such as heavy metals, toxic organic substances, and radiation substances, the present invention is for purification of wastewater containing polydopamine coated silica beads as an active ingredient. It provides a composition or a composition for adsorbing contaminants comprising silica beads coated with polydopamine as an active ingredient.

In one embodiment of the present invention by treating the polydopamine silica beads with acid and hydrogen peroxide, it was confirmed whether the contaminants and polydopamine are removed. In addition, it was confirmed whether or not reuse is possible by repeating the de-coating and recoating of the polydopamine by the hydrogen peroxide treatment. Therefore, the polydopamine silica beads of the present invention can be easily reused, thereby reducing resources and costs.

The present invention also relates to a method for producing polydopamine silica beads used in the wastewater purification and to polydopamine silica beads produced by the production method. The method for producing polydopamine silica beads is the same as described above.

As described above, the wastewater purification method of the present invention does not require the pretreatment, the manufacturing process is simple, has an energy saving effect used in the multi-step process, and has the effect of simultaneous removal of oil and minerals in the aqueous solution. In addition, the polydopamine silica beads of the present invention can be easily regenerated, thereby reducing resources and costs, and greatly reducing the problem of secondary contamination from the treatment of used filters.

1 shows silica beads coated with polydopamine.
2 is a comparison of heavy metal adsorption amount of activated carbon and polydopamine silica beads.
Figure 3 shows the results of XPS analysis before and after copper bonding of polydopamine silica beads.
Figure 4 shows the coordination of heavy metals to the polythepamine chitechol group based on the XPS analysis results.
Figure 5 shows the 4-AMP and 4-MBT adsorption amount of polydopamine silica beads.
Figure 6 shows the results of measuring the absorbance (red line) after absorbing 4-AMP with water (4-line) and polydopamine of 4-AMP containing water.
Figure 7 shows the results of measuring the absorbance (red line) after absorbing 4-MBT with water (4-line) and polydopamine of 4-MBT.
Figure 8 shows the results of measuring the radioactivity before and after polydopamine silica bead treatment of water contaminated with radioactive isotope 177Lu.
9 shows a process of regenerating beads by treating acid or hydrogen peroxide with polydopamine silica beads.
FIG. 10 shows changes in absorbance before and after acid treatment of polydopamine silica beads adsorbed with heavy metals (Cu, Cr, Cd, Pb from the left).
Figure 11 shows the difference in absorbance before and after hydrogen peroxide treatment of polydopamine silica beads.
FIG. 12 shows the results of confirming whether the beads can be reused by treating polydopamine silica beads with hydrogen peroxide and then recoating with hydrogen peroxide.

Hereinafter, the present invention will be described in detail by way of examples.

However, the following examples are illustrative of the present invention, and the present invention is not limited to the following examples.

≪ Example 1 >

Preparation of Polydopamine Silica Beads

Polydopamine was coated on silica beads (40-60 μm, Merck) in the following manner. Dopamine hydrochloride (Dopamine hydrochloride, Sigma Aldrich) was dissolved in tris buffer (10mM, pH8.5, 1 ~ 100mM) in a solution of 1mg / ml of silica beads and mixed for 3 hours. In order to remove the remaining dopamine after coating on the solution, the supernatant was repeatedly centrifuged until the color became transparent, and lyophilized to obtain polydopamine-coated silica beads (hereinafter referred to as polydopamine silica beads).

Coated polydopamine silica beads are shown in FIG. 1. Silica beads were discolored brown as shown in FIG. 1 when the polydopamine coating was completed.

<Example 2>

Contaminant Removal Effect of Polydopamine

<2-1> Heavy Metal Removal Effect

A 1000 ppm standard solution (Sigma Aldrich) of Cr (IV), Pb, Cd, Hg, Cu was diluted to 10 ppm to make a heavy metal solution. 1 g of polydopamine / silica bead was added to 10 ml of each heavy metal solution, followed by stirring for 2-3 hours. HCl solution was used to maintain the pH of each heavy metal solution as follows; Cu: pH 4.2-4.9, Hg: pH 3.5-4.0, Cr: pH 2.6-3.0, Cd: pH 5.2-6.8, Pb: pH 4.0-5.4.

In order to measure the adsorption amount of polydopamine silica beads to the heavy metal, polydopamine silica beads are placed in a heavy metal solution to adsorb the heavy metal, and then centrifuged to determine the concentration of the heavy metal in the supernatant. Spectroscopy, Varian Vista MPX). In addition, in order to compare the heavy metal adsorption effect of polydopamine with the previously reported effect of heavy metal adsorption by activated carbon, experiments were performed on the same solution using activated carbon.

As a result, as shown in Figure 2, the heavy metal adsorption amount of the polydopamine silica beads of the present invention was 2 to as much as 10 times higher than the conventional adsorption amount of activated carbon reported. However, for Hg, it appeared similar to activated carbon due to the adhesive property of Hg. In addition, even though each heavy metal solution had different pH conditions (Cu: pH 4.2 ~ 4.9, Hg: pH 3.5 ~ 4.0, Cr: pH 2.6 ~ 3.0, Cd: pH 5.2 ~ 6.8, Pb: pH 4.0 ~ 5.4) And all heavy metals were effectively removed, indicating that the adsorption of polydopamine coating occurs regardless of pH.

In addition, polydopamine silica beads were analyzed by XPS (X-ray photoelectron spectroscopy, ESCA probe, Omicron) before and after heavy metal adsorption to study the mechanism of adsorption of heavy metal to polydopamine. The C1s and N1s scans showed little difference before and after the adsorption of heavy metals (Cu), but the carbon-oxygen bond energy shifted to the larger side after the heavy metal adsorption. Therefore, Cu was selected as a representative metal for XPS analysis.

As a result, as shown in FIG. 3, the polydopamine O1s spectrum was fitted to two main peaks before adsorbing Cu. These are oxygen atoms in the C = O double bonds of the carbonyl group having a low binding energy (530.88 eV) and oxygen atoms of the hydroxyl group having a high binding energy (532.65 eV). Analyzed. After heavy metal adsorption each peak was observed to shift binding energy higher (532.65 → 533.13 eV, 530.88 → 531.68 eV). This suggests that the heavy metal ions coordinate with the oxygen atom of the polycatephamine group, resulting in lower electron-density of the carbon-oxygen bond, resulting in higher binding energy. That is, it was confirmed that the binding energy is observed due to the adsorption of heavy metals to polydopamine.

Based on the analysis results, the structure of the polydopamine in which the metal is coordinated to the catechol group is shown in FIG. 4.

<2-2> Removal effect of toxic organic substances

To confirm the organic material removal effect of polydopamine, toxic organic material removal experiments were conducted using 4-AMP and 4-MBT. 4-AMP is a component of insecticides and is a dangerous substance that can disrupt the central nervous system of mammals. 4-MBT also causes cyanosis (blood changes to dark blue due to oxygen deficiency) when entering the blood vessels. A toxic substance that can cause inflammation of the digestive and respiratory tracts.

First, polydopamine silica beads were placed in an organic toxic substance solution to adsorb the heavy metal, and then the maximum adsorption amount of organic polydopamine silica beads was analyzed using UV-Visible spectroscopy.

As a result, as shown in Figure 5, it can be seen that the adsorption amount of 4-AMP 18mg, 4-MBT 3.6mg per 1g polydopamine silica beads.

In addition, 4-AMP and 4-MBT (Sigma Aldrich) were dissolved in distilled water at 10 μg / ml, respectively, and passed through a column filled with 1 g of polydopamine / silica beads. 1 ml each of the filtrate was analyzed by UV-Visible spectroscopy (HP8453, Hewlett Packrad).

As a result, as shown in FIGS. 6 and 7, it was found that before purification with polydopamine silica beads, 4-AMP exhibited absorbance at 260 nm and 4-MBT at 240 nm. However, when the water contaminated with each organic material was purified by a polydopamine silica bead column, it was observed that ultraviolet absorption of 4-AMP and 4-MBT intrinsically disappeared. As a result, organic substances were purified while passing through the filter, and it was confirmed that each organic substance was not present in the filtrate.

<2-3> Removal Effect of Radioactive Isotopes

In order to confirm the radioisotope removal effect of polydopamine silica beads, radioisotope removal experiments were performed using Lutetium-177 ( ¹⁷⁷ Ru). ¹⁷⁷ Lu ( ¹⁷⁷ LuCl ₃ ) was produced in a radioactive reactor (KAERI; specific activity: 17.97 Ci / mg; volumetric activity: 8.17 Ci / 0.5 ml), using an ionizing chamber (Ionizing chamber, Atomlab 200, Bio-dex). Radioactivity was measured. The ¹⁷⁷ Lu stock solution was diluted in 50 mM HCl to make a solution with the desired concentration of radioactivity.

First, the purified solution was mixed with ¹⁷⁶ to ¹⁷⁷ Lu Lu to investigate the adsorption amount of the radioactive isotope of poly dopamine silica beads with poly dopamine / silica beads. ^As the concentration of ¹⁷⁷ Lu increases, the radioactivity of ¹⁷⁷ Lu increases, which is dangerous. Therefore, the amount of Lu was increased by adding ¹⁷⁶ Lu which does not emit radiation. At 1 ppm concentration 95% of the radioactivity was measured as the maximum adsorption amount. Since 1 ppm of radioisotope is an extremely high level of contamination, the adsorption power of the polydopamine / silica bead filter is therefore evaluated to be sufficient.

In addition, the following experiment was conducted to measure the radioisotope removal effect. Into the radioisotope solution (Sodium acetate buffer (pH5.5)) to dissolve the polydopamine silica beads in 800ml of 200ml ¹⁷⁷ Lu solution was added and stirred for 10 minutes. After stirring, the supernatant obtained by centrifugation was filtered (0.2 μm), and residual radioactivity was measured (Wallac 1470 Wizard Automated gamma counter, PerkinElmer Life Sciences).

As a result, as shown in Figure 8, when using the amount of ¹⁷⁷ Lu as 10 ° Ci (1.66ng ¹⁷⁷ Lu) showed 99.4% of the removal effect, even in the case of 2mCi (332ng) increased 200-fold 96% It was confirmed that is removed.

<Example 3>

Regeneration of Polydopamine Silica Beads

<3-1> Desorption of Contaminants by Acid Treatment

Heavy metal adsorbed polydopamine / silica beads were lyophilized. 10 ml of diluted acetic acid was added to 100 mg of dried polydopamine silica beads, followed by stirring for 2 hours. After stirring, the supernatant was discarded by centrifugation, and polydopamine silica beads were lyophilized and analyzed by XPS.

As a result, as shown in FIG. 9, in the case of the acid-treated polydopamine silica beads, only contaminants were removed. More specifically, as shown in FIG. 10, peaks corresponding to Cu (black), Pb (red), and Cd (purple) were analyzed to disappear completely after acid treatment, from which these heavy metals were effectively removed due to the acid treatment. You can see that it has been removed. However, for Cr (blue) the peak still appeared after acid treatment. This suggests the possibility of Cr ions adsorbing to polydopamine in a different pathway than other heavy metals. In addition, as shown in the red graph of FIG. 10, even after acid treatment, the N1s peak remained intact, indicating that the polydopamine coating was not removed. In the case of Hg, since the binding energy of Hg (Hg4f) is almost similar to that of the substrate Si (Si2p), it was difficult to determine whether it was desorbed with or without a peak. Therefore, the ratio of the Si2p / Hg4f peak and the Si2s peak was calculated to observe the change in the Hg4f peak. After acid treatment, the ratio of [Si2p, Hg4f] peak to [Si2s] peak was greatly reduced from 2.6618 to 1.8107, indicating that Hg was also effectively desorbed.

<If there is no test result for an acid other than acetic acid, it may be rejected in the claim. Even if there is no test result, it is necessary to mention that the treatment with an acid other than acetic acid can bring about the same pollutant removal effect.

In addition, we added contents for base, but in the case of base, it is not in the experiment example, so please comment to explain that the base treatment has the effect of removing contaminants. In the absence of such a statement, the examiner may refuse to claim that the claim is not supported by the detailed description of the invention.>

<3-2> Removal of polydopamine coating through hydrogen peroxide treatment

In order to remove the polydopamine itself from the beads with contaminants, 1 g of polydopamine silica beads were placed in 2 ml of 30% hydrogen peroxide (Mallinckrodt Chemicals) and stirred for one hour. After stirring, lyophilization and analysis by XPS.

As a result, as shown in Figure 9, it was found that the polydopamine coating and contaminants are removed together during the hydrogen peroxide treatment. That is, as shown in Figure 11, it was observed that the N1s peak of the polydopamine disappeared completely, from which it can be seen that the coating was effectively removed. Also, after the hydrogen peroxide treatment, the color of the beads changed from brown to the original white color.

<3-3> Check for repeat play of beads

As described above, by removing the polydopamine coated through the hydrogen peroxide treatment, and re-coating repeatedly, to determine whether the regeneration of the beads can be repeatedly, the polydopamine coating, and then treated with hydrogen peroxide to the polydopamine After removing and recoating, the process of removing it again was repeated and XPS analysis was performed. In XPS analysis, N1s peaks appear during the bead coating, the Si2p peaks of the substrate disappear, and vice versa when uncoated.

As a result, as shown in FIG. 12, it was observed that N1s peak and Si2p peak appeared and disappeared repeatedly. This is a result that means that repetitive reproduction of the beads is possible.

The present invention relates to a wastewater purification method using the adsorptive power of polydopamine, and more particularly, to manufacturing silica beads coated with polydopamine, and using the same, contaminants such as heavy metals, organic toxic substances and radioactive isotopes contained in the wastewater. The present invention relates to a wastewater purification method, a method for preparing wastewater refining polydopamine silica beads, and a polydopamine silica bead prepared by the production method. In addition, the manufacturing process is relatively simple, simultaneous removal of oil and minerals is possible, and the filter can be regenerated to solve the problem of secondary pollution along with resource and cost savings.

Claims (14)

(a) mixing and stirring silica beads in a solution in which dopamine hydrochloride salt is dissolved in a tris buffer having a pH of 8.0 to 9.0;
(b) centrifuging the solution of step (a) to remove excess polydopamine; And
(C) a method for producing polydopamine silica beads comprising the step of obtaining the silica beads precipitated in the step (b) and freeze drying.
Polydopamine silica beads prepared by the method of claim 1.
A method for purifying wastewater, comprising the step of adsorbing contaminants by adding polydopamine silica beads of claim 2 to the wastewater.
The method of claim 3, wherein the pollutant is selected from the group consisting of heavy metals, toxic organics and radioactive isotopes.
The method of claim 4, wherein the heavy metal is selected from the group consisting of Cr, Pb, Cd, Hg, Cu, Zn, Co, Ni, Mg, Fe, Mn, and Ca.
The method according to claim 4, wherein the toxic organic substance is 4-AMP (4-aminopyridine), 4-MBT (4-methylbenzenethiol), amitrol (amitrole), starlicide, dichloran (dichlororan), aminopyral Aminopyralid, butylamine, proxan, quinoclamine, thiosemicarbazide, fluoroacetamide, thioclorim, carbathion Wastewater purification method characterized in that the selected from the group consisting of.
5. The method of claim 4, wherein the radioactive isotope is ¹⁷⁷ Lu or ⁹⁰ Y.
4. The method of claim 3, further comprising the step of treating one selected from the group consisting of acid, base, and hydrogen peroxide to enable reuse of contaminant adsorbed silica beads.
The method of claim 8, wherein the acid is selected from the group consisting of acetic acid, hydrochloric acid, sulfuric acid, nitric acid, carbonic acid, phosphoric acid, hydroiodic acid, hydrobromic acid, chromic acid, boric acid, sulfuric acid hydrofluoric acid, and perchloric acid.
The method of claim 8, wherein the base is selected from the group consisting of sodium hydroxide, calcium hydroxide, potassium hydroxide, ammonium hydroxide, barium hydroxide, cesium hydroxide, strontium hydroxide, lithium hydroxide and rubidium hydroxide.
delete Wastewater purification composition comprising the polydopamine silica beads of claim 2.
A method for adsorbing contaminants comprising contacting the polydopamine silica beads of claim 2 with the contaminant to adsorb the contaminant.
Contaminant adsorption composition comprising the polydopamine silica beads of claim 2.

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