KR100610241B1 - Heavy metal adsorbent using kapok fiber, preparation method, and regeneration method thereof - Google Patents

Abstract

The present invention relates to a novel heavy metal adsorbent using kapok fibers, a method for producing the same, and a method for regenerating the same. More specifically, the present invention relates to a main component constituting fibers using kapok fiber, a natural vegetable material having a lipophilic and hollow structure. Heavy metal adsorbent using kapok fiber prepared by converting cellulose, hemicellulose, and lignin into water-soluble fibers which maximize the water absorption capability by chemical treatment, and converting these functional groups into functional groups having excellent heavy metal adsorption capacity, a method for preparing the same, and the same under suitable pH conditions As a regeneration method using regeneration, the heavy metal adsorbent according to the present invention not only has excellent heavy metal adsorption capacity, but is also recyclable and economical and environmentally friendly, thereby providing useful effects such as reducing secondary environmental pollution.

Carpok fiber, seed fiber, cotton fiber, heavy metal adsorbent

Description

Heavy Metal Adsorbent Using Kapok Fiber, Preparation Method, and Regeneration Method Thereof}

1 is a scanning electron micrograph showing an example of the hollow structure of the kapok fibers according to an embodiment of the present invention, 1a is a scanning electron micrograph showing an example of the hollow structure of the kapok fibers before the chemical treatment, 1b to the kapok fibers Photographs after NaClO ₂ treatment, 1c photographs after NaIO ₄ treatment with carpox fibers, and 1d photographs after NaClO ₂ retreatment with kapok fibers;

2 is a graph showing the adsorption and desorption capacity of heavy metal ions of the heavy metal adsorbent according to an embodiment of the present invention;

Figure 3 is a graph showing the desorption percentage according to the pH change of the heavy metal ions adsorbed on the heavy metal adsorbent according to an embodiment of the present invention; And

Figure 4 is a graph showing the adsorption and desorption capacity for the heavy metal ions of the regenerated adsorbent according to an embodiment of the present invention.

The present invention relates to a heavy metal adsorbent using a kapok fiber, a method for producing the same, and a method for regenerating the same. More specifically, the present invention relates to a new concept of improving the adsorption capacity of heavy metal ions by changing physical properties and functional groups of kapok fiber, which is a natural vegetable seed fiber. A natural heavy metal adsorbent, its manufacturing method and its regeneration method.

Today's industry and technology developments cause some problems. One of them is heavy metal contamination attracted from industrial waste. In recent years, the amount of industrial waste has increased so much that the disposal of industrial waste has become one of the most important problems for the industry.

The presence of heavy metals in the environment has been of major concern because its toxicity has a great impact on human life and the environment. Heavy metals in wastewater exist as soluble, insoluble, metalorganic and free metals, or in reduced, oxidized, adsorbed, precipitated and complexed forms. In nature it occurs in the form of oxides, carbonates, sulfides and silicates.

Many heavy metals are found in the waste water treatment process is a mineral form, the metal covering in particular industrial waste water treatment are Cu ^{+ 2.} A Zn ^{+ 2,} Cd ^{+ 2,} Pb ^{+ 2,} Ni ^{+ 2,} Hg ^{+ 2,} Cr ^{+ 6} and ^{2 +} Fe. Among these, Pb ^{2 +} , Cd ^{2 +} and Hg ^{2 +} are heavy metals classified as more important pollutants by the US Environmental Protection Agency (EPA). Anthropogenic sources of these heavy metals include electroplating and metal surface treatment, metallurgy, leather manufacturing, chemical manufacturing, mine drainage, battery manufacturing, leachate from landfills and contaminated groundwater from hazardous waste treatment plants.

The treatment of heavy metals in industrial wastes is largely divided into physicochemical methods including chemical flocculation and sedimentation-drainage, and biological methods including Acid Bacteria Sterilization, Bioleaching, and Lagon. Can be classified.

In the physicochemical treatment of wastewater containing high concentrations of heavy metals, the flocculation and precipitation processes (hydroxides, sulfides) are the most economical process, but most heavy metal wastewaters contain substances such as complexing agents, and therefore the efficiency of the precipitation process. In this case, the effluent contains a relatively high heavy metal concentration. In addition, wastewater and waste oil treatment using specially cultured or improved super bacteria and microorganisms, biological methods of removing contaminated heavy metals and removing toxic substances from chemical plant wastewater are well known examples.

In addition, several attempts have been made to remove heavy metals in industrial waste.

Korean Patent Laid-Open Publication No. 2005-24759 (2005.03.11) contains a sulfone structure in addition to the phosphono group as the overall chelating functional group, thereby chelating specific heavy metal ions due to the improvement of hydrophilicity and the addition of unshared electron pairs around the phosphono group. Phosphoric acid chelate resins based on poly (styrene-co-divinylbenzene) for adsorption of certain heavy metal ions with enhanced formation ability are disclosed, and Korean Patent Laid-Open No. 2002-6345 (2002.01.19) discloses a polymer base. Carboxyl group pairs are adjacent to the side chain of the skeleton and are arranged as chelate functional groups, and by utilizing the benzene of the basic skeleton as a spacer, the neighboring carboxyl group pairs form a concave-convex structure with each other, thereby making a specific heavy metal ion A chelate resin for heavy metal ion adsorption, which selectively enhances chelate formation ability against grasses, is disclosed. Korean Patent Laid-Open Publication No. 2003-86724 (Nov. 12, 2003), comprising: suspending polymerizing ethyl acrylate and divinylbenzene under a diluent to obtain crosslinked poly (ethyl acrylate) resin matrix beads; And reacting with the obtained cross-linked poly (ethyl acrylate) resin matrix beads and hydroxylamine to form a hydroxamic acid chelate resin. Is disclosed.

Korean Patent Laid-Open Publication No. 2003-61720 (July 22, 2003) uses a coal fly ash after burning in a coal-fired power plant, alkalizes with sodium hydroxide (NaOH) to zeolite, and then forms a spherical type. To remove heavy metals (P, Pb, Cd) and ammonia nitrogen from sewage and sewage, a complex adsorbent with a complex function to use as a carrier to grow microorganisms in sewage and sewage treatment facilities is started. have.

Korean Patent Laid-Open Publication No. 2003-73321 (September 19, 2003) discloses a method for continuous treatment of wastewater containing heavy metals using a waste iron oxide catalyst, and Korean Laid-Open Patent Publication No. 2003-50529 (2003.06.25) discloses wastewater sludge and capture. A heavy metal remover using starfish is disclosed, and Korean Laid-Open Patent Publication No. 2003-25260 (2003.03.28) discloses a method for treating heavy metal-containing wastewater by adsorbing and removing heavy metals using olivine fine powder, which is an adsorbent-induced oxidation mineral, as an adsorbent. In addition, Korean Patent Laid-Open No. 2001-94573 (2001.11.01) discloses a crab shell biosorbent that removes heavy metal ions in water, sewage, and wastewater using waste crab shells. In addition, Korean Patent Publication No. 199-12593 (1993.07.20) discloses chitosan produced by deacetylation from chitin extracted from crab or shrimp shells, using a flocculant solution to adsorb heavy metals in plated wastewater, food wastewater, livestock wastewater, and leather wastewater. A wastewater treatment agent is disclosed which aggregates and removes suspended matters. Korean Patent Laid-Open No. 2002-30443 (2002.04.25) utilizes various heavy metals contained in wastewater by utilizing sludge sludge, which is one of industrial wastes causing environmental pollution. A method of removal is disclosed.

Korean Unexamined Patent Publication No. 2003-16730 (2003.03.03) discloses a medium porous silica heavy metal adsorbent containing magnetite which can be recovered quickly and easily by using magnetic force after adsorbing a heavy metal.

Korean Patent Laid-Open Publication No. 2003-82510 (October 22, 2003) includes enterococcus pesium lactic acid bacteria having a high adsorption capacity for heavy metals isolated from feces of infants; In the production of dairy products such as fermented milk, cheese, butter, etc., lactobacillus strains with high adsorption capacity of heavy metals are disclosed. 2002-65010 (2002.08.13) and the like. In addition, Korean Patent Laid-Open Publication No. 2002-61248 (2002.07.24) discloses a method for removing heavy metals in an incineration ash using microorganisms.

However, the various physicochemical treatment methods as described above cause secondary environmental pollution, and there is a difficulty in recycling a large amount of sludge treatment, treatment agent and construction of technology, and biological treatment methods as described above also have a long treatment time. And control of purification efficiency is difficult.

The present inventors have intensively studied a result, NaClO ₂ in Kapok fibers having a lipophilic and a hollow structure in order to develop the conventional physicochemical and Hankyong view of the new concepts that can be substituted for the biological treatment type and heavy metal adsorbent recyclable And the chemical treatment method such as NaIO ₄ treatment to improve the physical properties of the fiber, and then introduce a carbonyl group and a carboxyl group having excellent adsorption capacity into the fiber to develop a heavy metal adsorbent having excellent heavy metal adsorption capacity and recyclability and completed the present invention. It was.

Accordingly, an object of the present invention is to provide a new concept of heavy metal adsorbent using kapok fiber that can be recycled as well as to minimize the secondary pollution and is economical and excellent in heavy metal adsorption capacity, a manufacturing method and a regeneration method thereof. There is this.

In order to achieve the above object, the present invention provides a natural heavy metal adsorbent using a carpok fiber introduced with a carbonyl group and a carboxyl group as a functional group.

In addition, the present invention to achieve the above object, the step of converting the lipophilic carpok fiber into hydrophilic carpok fiber; Introducing a carbonyl group into the carpox fiber; And it provides a method for producing a natural heavy metal adsorbent using a kapok fiber comprising the step of introducing a carboxyl group to the kapok fiber.

The present invention also provides a regeneration method for inducing the recycling of the natural heavy metal adsorbent using the kapok fiber in order to achieve the above another object.

Hereinafter, the present invention will be described in detail.

The present invention includes a natural heavy metal adsorbent using a carpok fiber, which is a natural seed fiber in which a carbonyl group and a carboxyl group are introduced as a functional group.

In the present invention, the seed fiber includes a seed fiber including a kapok fiber and a cotton fiber and a natural fiber derived from a plant, and is preferably a lipophilic kapok fiber having a hollow structure.

Water-soluble fiber by chemically treating cellulose, hemicellulose and lignin, which constitute the kapok fiber, which is a vegetable material having a lipophilic property and a hollow structure, by chemically treating the hollow structure within the extent that the hollow structure is not destroyed. After conversion to the functional groups of the main components can be converted to a carbonyl group and a carboxyl group to prepare a heavy metal adsorbent according to the present invention.

The present invention does not particularly limit the heavy metal to be adsorbed and removed, but preferably lead, cadmium, copper, zinc, arsenic, mercury, nickel and the like.

The natural heavy metal adsorbent of the present invention can be used by regeneration by desorbing the heavy metal adsorbed on the adsorbent in a solution in the range of pH 2 to 3 for the purpose of recycling to prevent secondary environmental pollution.

Method for producing a natural heavy metal adsorbent using a kapok fiber having the configuration as described above, Preferably, (a) converting the lipophilic carpok fiber to hydrophilic carpok fiber; (b) introducing a carbonyl group into the carpox fiber; And (c) introducing a carboxyl group into the kapok fiber.

Each of the steps (a), (b) and (c) is halogen-based treatment comprising sodium chlorate (NaClO ₂ ), sodium chlorite (NaClO) and sodium peroxate (NaIO ₄ ); Oxygen-based treatment including hydrogen peroxide (H ₂ O ₂ ), sodium perborate (NaBO ₃ ), oxygen (O ₂ ), and ozone (O ₃ ); And a reducing treatment comprising sodium sulfite (NaHSO ₃ ) and sodium hyposulfite (Na ₂ S ₂ O ₄ ). As a result, the hydrophilicity and the non-covalent pair of electrons of the kapok fiber may be increased, and the adsorbing capacity of heavy metal ions may be improved by increasing the spatiality of the functional group of the main component in the kapok fiber.

In step (a), the lipophilic carpok fiber is converted into hydrophilic carpok fiber.

Preferably, by treating the kapok fiber with sodium chlorite (NaClO ₂ ) to decompose lignin in the kapok fiber, the physical properties of the kapok fiber can be improved to a water-soluble fiber. As a result, by converting the kapok fibers into hydrophilic fibers, the absorption capacity of the kapok fibers to water can be maximized.

In step (b), a carbonyl (—C═O) group is introduced into the hydrophilic treated kapok fiber.

Preferably, the carbonyl group having excellent adsorptive capacity may be introduced into the kapok fiber by treating the carpox fiber with sodium peroxate (NaIO ₄ ) to decompose cellulose or hemicellulose in the carpoc fiber.

In step (c), a carboxyl (-COOH) group is introduced into the carpox fiber.

Preferably, the carboxyl group having excellent adsorption capacity can be introduced into the kapok fiber by reprocessing the kapok fiber with sodium chlorite (NaClO ₂ ) to decompose cellulose or hemicellulose in the kapok fiber.

The following reaction scheme is described by NaIO ₄ and NaClO ₂ as described above, respectively An example of the introduction process of treating and introducing a carbonyl group and a carboxyl group is illustrated.

Natural heavy metal adsorbent using kapok fiber prepared as described above can be used by regeneration. Preferably, the heavy metals adsorbed on the natural heavy metal adsorbent using the kapok fibers may be regenerated and used by desorption in a solution having a pH of 2 to 3. At this time, the heavy metal adsorption capacity at the time of regeneration was almost the same as the initial heavy metal adsorption capacity reaching 90% or more, and it was confirmed that the adsorbent according to the present invention could be used again as a heavy metal adsorbent in contaminated aqueous solution and then regenerated.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following examples are not intended to limit or limit the contents of the present invention only to the following examples to illustrate the best preferred embodiment in the present invention.

< Example  1> Preparation of Heavy Metal Adsorbent

In order to decompose lignin, one of the main components of the kapok fiber, 300 g of distilled water and 2 g of NaClO ₂ were mixed well with 5 g of fiber, and 0.5 mL of acetic acid was added. The reaction was carried out for a time. Thereafter, 2 g of NaClO ₂ and 0.5 mL of acetic acid were added every 1 hour to react three times, and then the kapok fibers were washed off with distilled water. (Hemi) cellulose was decomposed into NaClO ₂ treated fibers, and 5 L of distilled water, 50 mL of acetic acid, and 180 g of NaIO ₄ were mixed well with 5 g of fiber for introduction of carbonyl (-C = O) groups at room temperature. After standing for 10 minutes, the reaction was carried out at 20 ° C. for 3-7 days under dark conditions. Thereafter, 50 mL of ethylene glycol was added to terminate the reaction. After standing at room temperature for 1 day, the mixture was washed with distilled water. NaIO ₄ In order to introduce carboxyl (-COOH) group which has good adsorption ability of heavy metal to fiber with increased carbonyl group, reprocessing NaClO ₂ and finally increase the carboxyl group to carpox fiber to improve the physical and chemical properties. Developed.

A portion of the kapok fiber was taken from each treatment and the scanning electron microscopy (SEM) was used to observe the damage of the hollow structure of the fiber.

The results are shown in Fig. Figure 1a shows a picture of the hollow structure of the kapok fibers before improving the physical and chemical properties of the kapok fibers. As can be seen in FIG . 1B , NaClO ₂ The treatment was observed that the hollow structure was not damaged at all. As can be seen in Figure 1c , NaIO ₄ treatment was observed that the inner wall and outer wall of the fiber slightly damaged, but was generally maintained hollow structure. Also, as can be seen in Figure 1d , it was observed that the hollow structure of the fiber was well maintained even in the reprocessing of NaClO ₂ .

< Experimental Example  1> Heavy metal adsorption test

The heavy metals to be tested were Pb (lead), Cd (cadmium), Cu (copper), and Zn (zinc). The standard solution (1000 mg / L) of these commercially available heavy metals was purchased and diluted to 5.0 mg / L. Used for.

1 g of kapok fiber according to Example 1 was added to a 500 mL Erlenmeyer flask, and the four heavy metals were treated with 100 mL of 5 mg / L solution, respectively, by the stock solution method. The prepared triangular flask was shaken for 1 hour in a reciprocating shaker (rotation speed 180 / min). After the solution of the Erlenmeyer flask was filtered with a 0.45 ㎛ membrane filter, the filtrate was analyzed by using an atomic absorption spectrophotometer to analyze the concentration of heavy metals. The concentration of heavy metals remaining in the solution at the initial concentration of heavy metals was evaluated as the amount of heavy metals adsorbed by kapok fibers. The result is shown in Fig.

As can be seen in Figure 2 , the kapok fiber according to Example 1 is about 93% Pb (lead), about 78% Cd (cadmium), about 86% Cu (copper) and Zn (zinc) in the aqueous solution contaminated with heavy metals ) It is expected that it can be utilized as an excellent natural adsorption material because it can be purified by adsorbing about 91%.

< Experimental Example  2> Heavy metal desorption test

Dry the kapok fiber after the heavy metal adsorption test according to Experimental Example 1 for about 8 hours at 60 ° C, put it in the Erlenmeyer flask again, add 100 mL of deionized water, and shake the Erlenmeyer flask for 1 hour in a reciprocating shaker (rotational speed 180 / min) The procedure was performed. Filtration was performed in the same manner as the heavy metal adsorption test, and instrumental analysis was performed to determine the concentration of heavy metals in the aqueous solution. Thereafter, the amount present in the aqueous solution was evaluated by the amount of desorption. The result is shown in Fig.

As can be seen in Figure 2 , through the heavy metal adsorption test according to Experimental Example 1 was found that heavy metal ions adsorbed on the kapok fiber was kept fairly stable when physical energy was applied. That is, only about 1.7% of Pb (lead), about 3.2% of Cd (cadmium), about 3.7% of Cu (copper), and about 4.3% of Zn (zinc) among the heavy metal ions adsorbed on the kapok fiber were subjected to very strong physical forces. It was found to desorb from kapok fibers and back into aqueous solution.

These results indicate that Carpox fiber is a natural adsorbent material with very high binding constant of carboxyl or carbonyl group of Carpox fiber, so there is no concern about dissolution of heavy metal ions.

< Experimental Example  3> As heavy metal adsorbent Kapok  recycle Verification test

3-1) Kapok  Regeneration test

After drying heavy metal desorption test according to Experimental Example 2, dried the kapok fiber at 60 ° C for 8 hours, and then put it in a Erlenmeyer flask again. The pH was 2, 3, 4, 5, 6, 7 with HCl (hydrochloric acid) and NaOH (sodium hydroxide). 100 mL of the solution, adjusted to 8, 9 and 10, was shaken for 1 hour in a reciprocating shaker (rotational speed 180 / min). Filtration was performed in the same manner as the heavy metal adsorption test according to Experimental Example 1, and then the instrumental analysis was performed to determine the concentration of heavy metals in aqueous solution. The amount present in the aqueous solution was evaluated by the amount of desorption by the treated solution to regenerate the kapok fiber to verify whether it was recycled. The experimental results are shown in FIG. 3 .

As can be seen in Figure 3 , it was possible to remove about 92.36-100% of the adsorbed heavy metal as a whole, Pb (lead) about 70%, Cd (cadmium) about 73%, Cu ( Copper) about 72% and Zn (zinc) about 81%.

3-2) recycled Kapok  Heavy Metal Adsorption Test

The experiment of adsorption of heavy metal ions was performed again on the kapok fibers regenerated through Experimental Example 3-1) as in Experimental Example 1. The experimental results are shown in FIG. 4 .

As can be seen in Figure 4 , by adsorbing about 85% Pb (lead), about 81% Cd (cadmium), about 80% Cu (copper) and about 87% Zn (zinc) in the aqueous solution contaminated with heavy metal ions It has been shown to be cleansable.

3-3) recycled Kapok  Heavy metal desorption test

As a result of desorption experiment of heavy metal ions adsorbed on regenerated kapok fiber in the same manner as in Experiment 2, Pb (lead) of about 4.2% of heavy metal ions adsorbed on regenerated kapok fiber and Cd (cadmium) Only about 6.0%, about 4.0% Cu (copper) and about 5.1% Zn (zinc) were found to desorb from the kapok fibers and migrate back into the aqueous solution when very strong physical forces were applied. This may be due to the structural change of some functional groups during the regeneration of kapok fibers.

In summary, the present inventors confirmed that the heavy metal adsorbent using the kapok fiber according to the present invention can be used again as an adsorbent in an aqueous solution contaminated with heavy metal ions and then regenerated.

The natural heavy metal adsorbent using the kapok fiber according to the present invention having the configuration as described above not only has excellent heavy metal adsorption capacity of 90% or more, but also the heavy metal readsorption capacity after desorbing the heavy metals adsorbed under suitable pH conditions is almost the same as the initial use. I could confirm the same. Therefore, when the heavy metal adsorbent according to the present invention developed by modifying the kapok fiber, which is a natural fiber, can be recycled as compared with the existing heavy metal adsorbent, which is economical and useful to minimize the secondary environmental pollution caused by the heavy metal removal method. Can provide an effect.

Claims (11)

Natural heavy metal adsorbent using hydrophilic carpok fiber in which carbonyl group and carboxyl group are introduced as a functional group. The natural heavy metal adsorbent using kapok fibers according to claim 1, wherein the kapok fibers are plant-derived natural seed fibers. The method of claim 1, wherein the heavy metal is a natural heavy metal adsorbent using kapok fibers, characterized in that at least any one of lead, cadmium, copper, zinc, arsenic, mercury and nickel. The method according to any one of claims 1 to 3, wherein the natural heavy metal adsorbent using the kapok fiber is recycled by desorbing the heavy metals adsorbed on the adsorbent in a solution in the range of pH 2 to 3. Natural heavy metal adsorbent. Converting the lipophilic kapok fibers into hydrophilic carpoc fibers; Introducing a carbonyl group into the carpox fiber; And Method for producing a natural heavy metal adsorbent using a kapok fiber comprising the step of introducing a carboxyl group to the kapok fiber. 6. The method of claim 5, wherein the steps comprise halogen-based treatment, each comprising sodium chlorate, sodium chlorite and sodium peroxate; Oxygen-based treatments including hydrogen peroxide, sodium perborate, oxygen and ozone; And a chemical treatment method selected from reduction based treatments including sodium sulfite and sodium hyposulfite. The method of claim 5, wherein the kapok fiber is a plant-derived natural seed fiber. 7. The method according to claim 5 or 6, wherein the hydrophilic conversion step comprises decomposing lignin in the kapok fiber. 7. The method of claim 5 or 6, wherein the carbonyl group is introduced by decomposing cellulose or hemicellulose in the kapok fiber. The method according to claim 5 or 6, wherein the carboxyl group is introduced by decomposing cellulose or hemicellulose in the kapok fiber. The natural heavy metal adsorbent using the kapok fiber comprising the step of desorbing and recycling heavy metals adsorbed on the natural heavy metal adsorbent using the kapok fiber according to any one of claims 1 to 3 in a solution in the range of pH 2 to 3. How to play.

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