KR100380926B1 - A method for production of polymeric aluminum coagulant using wasted aluminum chloride solution - Google Patents

Abstract

The present invention relates to a method for producing a polymer aluminum flocculant using a waste aluminum chloride solution, and more particularly, a) by depositing waste aluminum pieces into a copper containing waste aluminum chloride solution to precipitate and remove copper from the waste aluminum chloride solution. Making a step; And b) adding a base to the waste aluminum chloride solution from which the copper produced in step a) is removed to produce a polymer aluminum complex compound.

According to the method of the present invention, the copper in the waste aluminum chloride solution can be removed to recycle the waste aluminum chloride solution as a flocculant for high functional wastewater treatment.

Description

A method for producing a polymer aluminum flocculant using a waste aluminum chloride solution {A METHOD FOR PRODUCTION OF POLYMERIC ALUMINUM COAGULANT USING WASTED ALUMINUM CHLORIDE SOLUTION}

The present invention relates to a method for producing a polymer aluminum flocculant using waste aluminum chloride solution. More specifically, the present invention relates to a method for preparing a high-functional wastewater treatment flocculant containing a large amount of aluminum complex compound in the form of polymer after removing the copper contained in the waste aluminum chloride solution.

The waste aluminum chloride solution is discharged as wastewater in a Cu-Phthalocyanine pigment production process. This waste aluminum chloride solution is a waste acid with a pH of 1 or less, which is a designated waste in the waste classification, and contains a large amount of copper, which causes considerable cost and difficulty in its treatment.

The methods for removing copper contained in the waste aluminum chloride solution include neutralization treatment according to hydroxide treatment, sulfide treatment, precipitation, and treatment by adsorption and ion exchange. However, the neutralization treatment of forming hydroxide with sodium hydroxide (NaOH) reacts with the waste aluminum chloride solution to form a slurry state, and the treatment cost increases rapidly. In the case of sulfide treatment using sodium sulfide (NaSH), hydrogen sulfide is used. (H ₂ S) As the gas is generated, the pressure in the reactor increases, which may cause an explosion. Meanwhile, waste acids among designated wastes are classified as waste sulfuric acid and waste hydrochloric acid. Waste aluminum chloride is classified as waste hydrochloric acid in waste acid, and waste sulfuric acid and waste hydrochloric acid are recycled as neutralizing agents. None reported.

In addition, as flocculants currently used in various water treatments, aluminum sulfate (Alum) and polyaluminum chloride (PAC) are used. Among them, PAC contains more polymer species than Alum, so the use of PAC in water treatment is excellent. PAC is prepared by adding hydrochloric acid (HCl) to aluminum hydroxide (Al (OH) ₃ ) as a raw material and sulfuric acid (H ₂ SO ₄ ) as a catalyst, and the aluminum complex in polymer form is maintained in the PAC. . However, the polymer content of the PAC thus prepared is only 20 to 30%.

Therefore, there is a need for a method for removing copper contained in the waste aluminum chloride and recycling the same, and at the same time, a method for preparing a flocculant containing a large amount of aluminum in a polymer form is required.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and the present inventors have deposited copper by injecting a waste aluminum piece having a relatively strong ionization tendency in the waste aluminum chloride solution and having a property of being dissolved in both acid and alkali as an amphoteric element. The present invention has been accomplished by increasing the content of aluminum in the solution and injecting a base into the solution to produce a flocculant containing a large amount of the aluminum complex in the form of a polymer by hydrolysis.

Accordingly, an object of the present invention is to provide a method of removing a copper contained in waste aluminum chloride and using it to prepare a flocculant containing a large amount of aluminum in the form of a polymer.

1 is a production process chart showing a method for producing a polymer aluminum flocculant of the present invention.

2 is a curve showing the change of pH and the change of basicity (OH _addition / Al) with addition of a base.

3 is a graph showing the content distribution of Al (III) species in the flocculant according to basicity.

4 shows ²⁷ Al NMR spectra of flocculants according to basicity.

Figure 5 shows the results of the FT-IR analysis of the flocculant.

In order to achieve the above object, the present invention comprises the steps of a) depositing and removing copper from the waste aluminum chloride solution by injecting a waste aluminum piece into a copper-containing waste aluminum chloride solution; And b) adding a base to the waste aluminum chloride solution from which the copper produced in step a) is removed to produce a polymer aluminum complex compound.

In step a), it is preferable to add 50 to 80 g of waste aluminum per liter of waste aluminum chloride solution.

The base used in step b) is preferably sodium hydroxide (NaOH) which is a strong base.

Also in step b), the basicity, ie the molar ratio of OH to Al, is preferably between 0.4 and 2.3, most preferably 2.2.

Hereinafter, the present invention will be described in detail.

(1) copper precipitation and removal step

Step a) is a step of depositing and removing copper from the waste aluminum chloride solution by injecting waste aluminum pieces into the waste aluminum chloride solution.

Preference is given to adding 50 to 80 g of waste aluminum per liter of waste aluminum chloride solution.

The metal atom has a property of giving out electrons and becoming a stable cation, which is called the ionization tendency of the metal, depending on the type of metal as follows.

Li> Cs> K> Ba> Sr> Ca> Na> Mg> Be> Al> Mn> Zn> Cr> Fe> Cd> Co> Ni> Sn> Pb> (H)> Sb> Cu> Hg > Ag> Pt> Au (about)

Metals with a high tendency to ionize are easily oxidized to form compounds or ions. Therefore, in step a) of the present invention, waste aluminum salts are reacted by reacting aluminum chloride solution containing a large amount of copper with a large amount of copper according to Scheme 1 below. The copper contained in the aluminum sulfide solution can be precipitated and removed, and at the same time, the concentration of aluminum ions can be increased.

Scheme 1

2Al + 3Cu ²⁺ → 2Al ³⁺ + 3Cu

(2) Preparation Step of Polymeric Aluminum Complex

Step b) is a step of adding a base to the waste aluminum chloride solution from which the copper produced in step a) is removed to produce a polymeric aluminum complex.

In step b), NaOH, Ca (OH) ₂ , Mg (OH) ₂ , Na ₂ CO ₃ , NaHCO _3, etc. may be used as the base, and NaOH is preferably used.

In the process of preparing polyaluminum chloride (PAC) using aluminum chloride, the pH change according to the change of base addition rate, that is, r (OH _addition / Al) value is shown in FIG. 2.

Section I, which is the base of the base injection, is a range of 0 ≤ r ≤ 0.3 where the rapid pH change and hydrolysis begin as the value of r increases, and the Al (III) hydrolyzed species formed in this section is Al ³⁺ And monomeric Al (III) species such as AlOH ²⁺ .

Section II is in the range of 0.4 ≤ r ≤ 2.3 and pH range suitable for generating polymer Al (III) species upon injection of OH ^- ions, and the added OH ^- ions are polymers formed by complexation with Al (III). As the transition to the Al (III) component, the increase in pH due to the addition of OH ^- ions appears very small.

Section III is formed by polymer Al (III) species that can no longer be bonded to Al (III) with the increase of OH ^- ions added in the range of r is 2.35 or more, and is formed as the pH is rapidly increased by base injection. This is the section in which polymer Al (III) species are transferred to precipitated Al (III) species.

As described above, the Al (III) species in the coagulant are varied depending on the addition rate of the base, and the difference in the coagulation efficiency is shown depending on the Al (III) species contained in the coagulant.

Therefore, in the step b), by producing a flocculant to contain a large amount of polymer Al (III) species, it is possible to increase the treatment efficiency for the treatment of suspended materials and organic matter.

Al (III) species contained in the flocculant prepared according to the method of the present invention were analyzed using the Ferron method.

This is described in Smith, RM, 1971, Relation among equilbrium and nonequilibrium aqueous species of aluminum hydroxy complexes, Nonequilibrium systems in natural water chemistry (Gould, RF eds.), ACS Advances in Chemistry Sereis No. Monomer Al (III), as shown in 106, Washington, DC, 250-279 and Smith, RW and Hem, JD, 1972, Effects of aging on aluminum hydroxide complexes in dilute aqueous solutions, USGS Water-Supply Paper 1827-D. Under the assumption that the species reacts immediately with the Ferron reagent, the absorbance values of the Al (III) -Ferron reaction time at 370 nm are used to distinguish between the monomeric Al (III) species and the polymer Al (III) species. The absorbance value at the reaction time of 30 seconds is the monomeric Al (III) species, the absorbance value involved in the reaction up to 120 minutes is the polymer Al (III) species, and the chemical species in the case of the subsequent very slow reaction appear. Shown as Al (III) species. Therefore, the polymer Al (III) species can be obtained using the absorbance difference in the reaction from 30 seconds to 120 minutes.

As a result of Al (III) species analysis on the change of absorbance according to Al-Ferron reaction, the content of Al (III) species contained in each flocculant is shown in FIG. 3. As shown in FIG. 3, the monomer Al (III) species decreased and the polymer Al (III) species increased with increasing r value. In addition, when r is 2.2, the polymer Al (III) species was found to contain the highest amount of 85%, and the polymer Al (III) species decreased and the precipitated Al (III) species increased at 2.35.

As a result of the preparation of the flocculant according to the addition rate of the base as described above, a PACl flocculant having r of 2.2 can be derived as the flocculent containing the most polymer Al (III) species.

In addition, the characteristics of the flocculant of the present invention were examined using ²⁷ Al-NMR and FT-IR methods.

4 is a result of ²⁷ Al-NMR measured with 1.0 M AlCl ₃ .6H ₂ O as an external reference solution for the flocculant prepared by varying r value. The manufacturing conditions are prepared at 50 ℃, it can be seen that the appearance of the peak is different according to the r value.

As shown in Figure 4, it can be seen that the peak appears in three areas, the peak appearing at 0 ppm are mainly Al (III) species Al (H ₂ O) 6 ^{3 +} , Al (OH) (H ₂ O ) 5 ²⁺ and Al (OH) ₂ (H ₂ O) P, the peak appearing in the 4 ppm section is present as Al (OH) ₃ in the form of precipitate, and the peak in the 63.4 ppm section is the polymer Al ( III) Species The form of the Al (III) species present here is in the form of a polymer of [Al ₁₃ O ₄ (OH) ₂₄ (H ₂ O) ₁₂ ] ⁷⁺ . These results, Bottero, JY, Cases, JM, Fiessinger, F., and Poirer, JE, 1980, Studies of hydrolyzed aluminum chloride solutions. I. Nature of aluminum species and composition of aqueous solution, J. of Phys. Chem ., 84; 2933-2939; Akitt, JW and Farthing, A., 1978, New Al NMR studies of the hydrolysis of aluminum ions, J. Mag. Since the peaks for polymer Al (III) species appear at frequencies similar to 62.5 ppm according to Al-NMR conducted in Reson ., 32,345, etc., the inclusion of polymer Al (III) species according to the preparation of Al (III) inorganic polymer flocculants You can check the degree. However, if r is 2.35, the peak at 0 ppm, which represents the monomeric Al (III) species, was not observed, but the small peak was maintained at 0 to 85 ppm, believed to be due to the transition to the precipitated Al (III) species. Lose.

5 shows the results of analysis using FT-IR to determine the form of crystals for the Al (III) species formed in the flocculant of the present invention. Looking at the variation in the FT-IR of the flocculant according to the value of r, the absorption band was formed in the region of 600, 800, 1200 and 1600 cm ^-1, with an increase in the r value, the absorption bands at 600 and 800cm ^-1 It appears to weaken and the absorption band at 1200 cm ⁻¹ appears to be obscured by the surrounding wide band. At this time, the bands formed at 600, 800 and 1200 cm ^-1 indicate water molecules coordinated to Al (III) atoms, and the absorption bands appearing at 1600 cm ^-1 indicate the presence of water molecules. Weak absorption bands at 600, 800, and 1200 cm ⁻¹ with increasing r value are water molecules that coordinate to Al (III) atoms as the monomer Al (III) species changes to the structure of the polymer Al (III) species. Is believed to be the result of the decrease.

In addition, as the value of r increases, an absorption band that does not appear when r is 0.0 is generated at 1000 cm ⁻¹ , which is formed by the continuous Al-OH bonding. It can be predicted that Al (III) species are produced.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, this is only to illustrate the present invention, the present invention is not limited thereto.

EXAMPLE

The aluminum sash was cut at the time of product shipment at the factory and the remaining aluminum scrap was collected and cut into a size of 2.0 × 1.0 × 0.5 cm with a cutter. The specific gravity of the aluminum pieces was 2.73 at 20 ° C. Table 1 shows the composition of the aluminum sash pieces presented to the Korea Industrial Standards Association (KS).

heavy metal density(%) heavy metal density(%) Cu <0.04 Mg <0.03 Si <0.20 Zn <0.04 Fe <0.25 Ti <0.03 Mn <0.03 Al <99.70

Analysis item Zn Mn Fe Cu Al * Al ₂ O ₃ unit mg / l % content 16.0 19.4 1,260 1,883 34,412 6.5

60 kg of aluminum sash pieces having the composition shown in Table 1 were added to 1 m ³ of the waste aluminum chloride solution having the composition shown in Table 2, and reacted with stirring at about 120 rpm for 5 hours. After the reaction, copper and other heavy metals deposited in the solution were removed by filtration with a filter cloth (1 mu m). 1 m ³ of this solution was placed in a 50 ° C. constant temperature reactor, and a 10 M NaOH solution was injected at 200 L / hr for about 2 hours under a stirring speed of 250 rpm to prepare polymer aluminum. A flocculant 1.4 m ³ was prepared by this process, and the properties thereof are shown in Table 3 below.

Item Zn Mn Fe Cu Al Al ₂ O ₃ importance pH Basicity (r = OH _addition / Al) Al (III) species content (%) (mg / l) (%) Monomer Polymer Sedimentation content 6 10.1 512.8 0.93 34.020 6.95 1.24 3.35 2.2 2.3 85 12.7

The flocculation efficiency of the coagulant of the present invention and the other aluminum-based flocculant PAC and Alum dyeing, leather and chemical wastewater was compared. The results are shown in Table 4 below.

Experimental wastewater Dyeing Plant Wastewater Leather manufacturing plant wastewater Chemical plant wastewater Flocculant Invention PAC Alum Invention PAC Alum Invention PAC Alum Injection amount (ppm) 500 800 1,000 700 1,000 1,500 700 1,000 1,500 Adjustable pH 8.0 8.0 8.0 7.0 7.0 7.0 6.0 6.0 5.0 COD removal rate (%) 37.2 33.9 35.5 55.7 55.0 53.3 26.2 21.9 23.8 SS removal rate (%) 80.6 77.8 66.7 99.3 99.3 98.8 98.5 97.9 98.8 Color removal rate (%) 97.6 74.3 65.9 - - - - - -

As can be seen from the table, in the case of the dye wastewater, the COD and SS removal efficiencies at the optimum injection amount of 500 ppm and the optimum pH 8 of the present invention were 37.2 and 80.6%, respectively, slightly higher than PAC and Alum. In the case of leather wastewater, all three flocculants were similar in the appropriate flocculant injection amount and pH conditions, but when using the flocculant of the present invention, a rather high COD removal efficiency was obtained. SS removal efficiency of all three flocculants was about 99%. Similar results were found for chemical wastewater.

From the above results, it can be seen that the flocculant of the present invention is somewhat higher than other aluminum flocculant in terms of flocculation efficiency.

As described above, the present invention removes the copper contained in the waste aluminum chloride to enable its recycling as a flocculant, and the flocculant prepared according to the present invention contains a large amount of aluminum in a polymer form, and thus has excellent coagulation efficiency.

Claims (5)

a) depositing and removing copper from the waste aluminum chloride solution by introducing waste aluminum pieces into a copper-containing waste aluminum chloride solution; And b) adding a base to the waste aluminum chloride solution from which the copper produced in step a) is removed to produce a polymer aluminum complex Method for producing a polymer aluminum flocculant comprising a. The method of claim 1 wherein the base used in step b) is sodium hydroxide (NaOH). The method of claim 1 or 2, wherein in step b), a base is added so that the molar ratio of OH to Al is between 0.4 and 2.3. The process according to claim 1 or 2, wherein in step b), a base is added so that the molar ratio of OH to Al is 2.2. The method according to claim 1 or 2, wherein in step a) 50 to 80 g of the waste aluminum pieces are added per liter of the copper-containing waste aluminum chloride solution.