JP3517697B2 - Method and remover for removing heavy metal ions - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method and a removing agent for removing dissolved heavy metal ions in water.

[0002]

2. Description of the Related Art Conventionally, as a method for removing dissolved heavy metal ions contained in water, a method of adding an alkaline substance such as sodium hydroxide or calcium hydroxide to water and precipitating it as a hydroxide is known. There is. In such a method, when sodium hydroxide is used as the alkaline substance, the amount of sludge (heavy metal hydroxide) generated is small, but the sludge particles are small and difficult to separate. Therefore, until now, calcium hydroxide has been exclusively used, but in this case, there is a drawback that a large amount of sludge is generated.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for efficiently removing dissolved heavy metal ions contained in water with a reduced sludge generation amount, and a heavy metal ion removing agent used therefor. And

[0004]

The present inventors have completed the present invention as a result of intensive studies to solve the above problems. That is, according to the present invention, in a method for removing heavy metal ions contained in water, in the aqueous, powder powder-like or polymeric material ing of a mixture of anionic group-containing hydrophilic polymeric substance with sodium hydroxide A non-dissolved aqueous liquid heavy metal ion removing agent is added, and
Provided is a method for removing heavy metal ions, which comprises insolubilizing a dissolved heavy metal ion contained in water by dispersing a molecular substance in water without dissolving it. Further, according to the present invention, there is provided a removing agent for removing dissolved heavy metal ions contained in the water, Ri Na <br/> a mixture of anionic group-containing hydrophilic polymeric substance with sodium hydroxide, powder Liquid containing a polymer or the polymer substance in a non-dissolved form
If the removing agent is put in water,
Child material removing agent of heavy metal ions, characterized in der Rukoto those existing in the state of insoluble is provided.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The heavy metal ion removing agent of the present invention (hereinafter, also simply referred to as a removing agent) is an anionic group-containing hydrophilic polymer substance, sodium hydroxide and, if necessary, a harmless polyvalent metal compound. It is composed of a mixture of The anion group-containing hydrophilic polymer substance includes various polymer substances containing anion groups such as a carboxyl group, a sulfonic acid group and a phosphoric acid group, and both natural products and synthetic products can be used. From the viewpoint of conservation, it is preferable to use those having biodegradability. Such high molecular substances include alginic acid, dielan gum, xanthan gum, tragacanth gum, pectin, pectic acid, pectinic acid, carrageenan, gelatin, agar, anionized starch, propylene glycol alginate, carboxymethyl cellulose, starch glycolic acid, fibrin glycol. acid,
Polysaccharides such as starch phosphate and galactomannan and alkali metal salts thereof; polyacrylic acid, copolymers of acrylamide and acrylic acid and metal salts thereof; super absorbent polymers (for example, Sumika Gel manufactured by Sumitomo Chemical Co., Ltd. , Sanyo Kasei Co., Ltd., “Sunwet”, Showa Denko KK, “Pre-Apple”, Nisseki Kagaku KK, “WAS”, etc.) and the like.
Examples of the anionic group-containing hydrophilic polymer substance include (i)
Ruginic acid or its salt or (ii) alginic acid or
Mixing the salt with other hydrophilic polymer containing anion groups
Thing, (i) pectin, pectic acid or their salts
Or (ii) with pectin, pectic acid or salts thereof
Mixture with other anionic group-containing hydrophilic polymer, and
(I) Polyacrylic acid, acrylamide and acrylic acid
Or a salt thereof or (ii) polyacrylic acid,
Copolymer of acrylamide and acrylic acid or its
A mixture of salt and other hydrophilic polymer containing anionic groups
Can be mentioned.

In the present invention, it is particularly preferable to use sodium alginate or calcium alginate. When this is used, the content ratio of mannumamaronic acid (M) and guluronic acid (G) constituting alginic acid (mol ratio)
[M] / [G] is 0.1 to 4.0, preferably 0.1.
It is preferable to use those in the range of 3 to 3. The higher the content ratio of guluronic acid, the better the floc forming property. These anionic group-containing hydrophilic polymer substances are usually used in powder form (including short fiber form), and the average particle size thereof is 10 to 500 μm, preferably 20 to 200 μm.
m, more preferably 50 to 150 μm.

The anionic group-containing hydrophilic polymer substance used as the remover component in the present invention can be used alone or in the form of a mixture.

The removing agent of the present invention contains sodium hydroxide.
Have. This sodium hydroxide has an action of controlling the solubility of the anionic group-containing hydrophilic high molecular weight substance, and the like. The proportion of sodium hydroxide used is not particularly limited and is appropriately selected depending on the type and amount of heavy metal ions dissolved in water, the pH of the water to be treated, etc.
Generally, 1 to 2000 parts by weight, preferably 10 to 10 parts by weight, relative to 1 part by weight of the anionic group-containing hydrophilic polymer substance.
The amount is 00 parts by weight, more preferably 50 to 1000 parts by weight.

The removing agent of the present invention optionally contains a harmless polyvalent metal compound. In addition to iron salts such as ferrous sulfate, ferric sulfate, ferrous chloride and ferric chloride, aluminum sulfate, aluminum chloride, calcium hydroxide, calcium chloride, magnesium sulfate, chloride Magnesium, magnesium hydroxide and the like are included. In the present invention, ferrous sulfate heptahydrate is preferably used in terms of storage stability and price. These polyvalent metal compounds form an ionic bond or a chelate bond with respect to the anionic group-containing hydrophilic polymer substance, and exhibit the action of controlling the solubility of the polymer substance. The proportion of the polyvalent metal compound used is not particularly limited and is appropriately selected depending on the type and amount of metal ions dissolved in water, the pH of the water to be treated, and the like. Generally, anionic group-containing hydrophilic polymer substances are used. 1 to 10,000 parts by weight, preferably 20 to 100 parts by weight
The amount is 5000 parts by weight, and more preferably 100 to 2000 parts by weight.

[0010] removing agent of the present invention, Oh aqueous liquid containing powder or the anion group-containing hydrophilic polymeric substance in undissolved form
Then, it is put into water and dispersed, but when the remover is put and dispersed in water in this way, the anionic group-containing hydrophilic substance contained therein is not dissolved and is insoluble (water-insoluble).
Exists in the state of. One embodiment of the preferred remover according to the present invention is an aqueous liquid containing an anionic group-containing hydrophilic polymer and sodium hydroxide, and the concentration of the sodium hydroxide is high. In this aqueous liquid, the sodium hydroxide concentration is 10 to 52% by weight, preferably 2
It is 0 to 50% by weight. The concentration of the anionic group-containing hydrophilic polymer substance is 0.005 to 10% by weight, preferably 0.01 to 3% by weight.

Another preferred embodiment according to the present invention is an aqueous liquid containing an anionic group-containing hydrophilic polymer, sodium hydroxide and a harmless polyvalent metal compound, and the concentration of sodium hydroxide is high. . In this aqueous liquid, the concentration of sodium hydroxide is 5 to 52% by weight, preferably 10 to 50% by weight. The concentration of the anionic group-containing hydrophilic polymer substance is 0.005 to 10% by weight, preferably 0.01 to 3% by weight. The concentration of the harmless polyvalent metal compound is 0.03 to 20% by weight, preferably 0.3 to
It is 10% by weight. In this aqueous liquid, the anionic group-containing hydrophilic polymer substance exists in a non-dissolved state. It is particularly preferable to use ferrous sulfate as the harmless polyvalent metal compound.

In the removing agent of the present invention, it is preferable to use a coagulant together. The aggregating agent in this case is used for floc aggregating, and in such a thing,
In addition to inorganic flocculants such as chitosan, calcium chloride, calcium bis (dihydrogen phosphate), ferrous chloride, ferric chloride, ferrous sulfate, ferric sulfate, aluminum sulfate, polyaluminum chloride, poly Cationic organic flocculants such as cation-modified acrylamide, polyacrylic acid dimethylaminoethyl ester, polymethacrylic acid dimethylaminoethyl ester, polyethyleneimine, chitosan, etc.,
Nonionic organic flocculants such as polyacrylamide, anionic organic flocculants such as polyacrylic acid, copolymers of acrylamide and acrylic acid, and salts thereof are included.

Examples of wastewater to which the present invention is applied include wastewater containing one or more dissolved polyvalent heavy metal ions such as copper ions, zinc ions, nickel ions, lead ions, chromium ions and iron ions. . There is no particular limitation on the concentration of heavy metal ions in this wastewater, and there is no limitation on other coexisting ions.

In order to remove the dissolved heavy metal ions contained in water using the removing agent of the present invention, the removing agent is put into the water and dispersed to insolubilize the heavy metal ions. In this case, the hydroxide contained in the remover added to the water
The amount of sodium iodide is equal to or more than the theoretical amount required to precipitate dissolved heavy metal ions contained in water as an insoluble metal hydroxide, usually 1 to 1.5 times the theoretical amount, preferably 1 to It is added in the ratio of 1.2 times. When the amount of sodium hydroxide in the remover added to water is insufficient, sodium hydroxide may be added after the remover is added, and the heavy metal ions in the dissolved state may be precipitated as insoluble hydroxide. In addition, in order to make the removal of heavy metal ions more complete, after adding the removing agent, the pH of the water to be treated is
It is preferable to adjust the range of 6 to 12, preferably 7 to 11.

When the heavy metal ions dissolved in the wastewater are removed by using the removing agent of the present invention, the wastewater is preferably acidic wastewater, but when the wastewater is neutral or alkaline, the wastewater is previously discharged. The pH of the acidic range, usually
It is preferable to adjust the pH to a range of 1 to 7, preferably 2 to 4. However, such pre-adjustment of pH is not always necessary, and in the case of the present invention, the neutral or alkaline waste water is added with the removing agent of the present invention, and then its pH is adjusted as necessary. It can be adjusted within the range of 6 to 12, preferably within the range of 6 to 10.

When the pH of the water to be treated is adjusted to an alkaline range or an acidic range, a pH adjusting agent is used. Examples of such a pH adjusting agent include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, An alkaline substance such as calcium hydroxide or an acidic substance such as hydrochloric acid, sulfuric acid or nitric acid is used.

The gel in which the insolubilized heavy metal ions generated as described above are adsorbed or taken in is usually a floc capable of solid-liquid separation, but when the floc is not sufficient, a flocculant is added to make the gel larger and stronger. Can be flock. In the present invention, the flocs produced as described above are separated from water by the solid-liquid separation method. As the solid-liquid separation method in this case, a conventional method such as a filtration method, a centrifugation method, or a precipitation method can be adopted. The treatment time for removing dissolved heavy metal ions from the water according to the invention is very short, usually within 1 hour, in particular 30.
Within minutes, preferably 3 to 10 minutes.

In carrying out the present invention, as the anionic group-containing hydrophilic polymer substance, a water-soluble substance such as alginic acid or an alkali metal salt thereof is used. In the present invention, such a water-soluble substance is used. It is possible to smoothly use even polymer materials. That is, even if the anionic group-containing hydrophilic polymer is water-soluble, it can be dissolved by pouring and dispersing it in water as a mixture with an alkaline substance and a harmless polyvalent metal compound. Can be prevented. Further, the use of calcium alginate, which has low solubility, can prevent the dissolution more effectively. Therefore, in the case of the present invention, the heavy metal ions may be insolubilized and solid-liquid separated under the condition that the powder of the polymer substance is not completely dissolved. When practicing the present invention, an aggregating agent can be added if necessary. The addition of this aggregating agent has the effect of aggregating the insoluble matter of harmful heavy metal ions in addition to the anionic group-containing hydrophilic polymer substance dispersed in water to form a giant floc.

In the present invention, when removing heavy metal ions contained in acidic water, first, a removing agent is added to the acidic water, and if necessary, alkali is added and the whole is stirred. As a result, heavy metal ions contained in water are insolubilized. At this time, some of the heavy metal ions contained in the water are
Reacts with anionic group-containing hydrophilic polymeric material to form an insoluble salt of the polymeric material resulting in precipitation. And at this time, due to the presence of the anionic group-containing hydrophilic polymer,
Ru can be more greatly grow flocs generated heavy metal hydroxides. Furthermore, by adding a coagulant, larger and stronger flocs can be precipitated.

In the present invention, the heavy metal-containing wastewater used as raw water to be treated includes wastewater from various factories such as semiconductor manufacturing industry, iron and steel / nonferrous metal industry, electrical equipment manufacturing industry, machinery / equipment manufacturing industry, and plating factory. Drainage, drainage from various laboratories, etc. are included. Most of these effluents contain harmful heavy metals. The present invention generally relates to Cu, Zn,
Cd, Pd, Ag, Al, Cr, Pb, Mn, Fe, N
It can be applied as a method for treating wastewater containing various heavy metals such as i.

[0021]

EXAMPLES Next, the present invention will be described in more detail by way of examples. Although the following examples further illustrate the invention,
It is in no way intended to limit the scope of the claimed invention.

Treatment Example 1 0.12% by weight of sodium alginate was added to a 48% by weight aqueous solution of sodium hydroxide, the mixture was stirred at 50 ° C. for 40 minutes, and then 0.88% by weight of ferrous sulfate heptahydrate was added, 5
After stirring for 40 minutes at 0 ° C., a gray suspension resulted. This was designated as a remover [I]. This removing agent [I]
PH containing 100ppm each of copper, nickel, lead and zinc
When sodium alginate and ferrous sulfate were added to the treated water of No. 2 so that the total concentration was 12 ppm, p
It became H10. After stirring for 10 minutes, solid-liquid separation was performed, and the residual metal ion concentration was measured. As a result, copper 0.036
ppm, nickel 0.074 ppm, lead 0.153 pp
m, zinc was 0.066 ppm, and good results were obtained.

Treatment Example 2 (Comparative Example) An experiment was conducted in the same manner as in Treatment Example 1 except that 660 ppm of calcium hydroxide was added to the water to be treated instead of the removing agent [I]. As a result, the residual metal ion concentration of the treated water was 0.175 ppm for copper and 0.225 pp for nickel.
m, lead 0.270 pm and zinc 0.211 ppm.

Treatment Example 3 (Comparative Example) An experiment was conducted in the same manner as in Treatment Example 1 except that sodium hydroxide was added in place of the removing agent [I] until the pH became 10. As a result, the residual metal ion concentration of the treated water was 0.294 ppm for copper, 0.583 ppm for nickel,
Lead was 0.271 ppm and zinc was 0.567 ppm.

Treatment Example 4 0.12% by weight of sodium alginate was added to a 48% by weight aqueous solution of sodium hydroxide and stirred at 50 ° C. for 40 minutes to prepare a suspension, which was used as a remover [II]. An experiment was conducted in the same manner as in Treatment Example 1 except that this removing agent [II] was used. As a result, the residual metal ion concentration of the treated water was 0.035 ppm for copper, 0.083 ppm for nickel,
Lead was 0.173 ppm and zinc was 0.073 ppm, and good results were obtained.

Treatment Example 5 (Comparative Example) In Treatment Example 1, 12 ppm of ferrous sulfate heptahydrate was added in place of the removing agent [I], and sodium hydroxide was added to p.
The experiment was performed in the same manner except that the addition was performed until H10 was reached. As a result, the residual metal ion concentration of the treated water was 0.2%.
146ppm, nickel 0.329ppm, lead 0.20
It was 5 ppm and zinc 0.286 ppm.

Treatment Example 6 A mixture of 0.12% by weight of sodium alginate and 0.88% by weight of ferrous sulfate heptahydrate was added to a 48% by weight aqueous solution of sodium hydroxide, and the mixture was stirred at 60 ° C. for 2 hours. It became a black suspension. This was designated as a remover [III]. An experiment was performed in the same manner as in Treatment Agent 1 except that this removing agent [III] was used. As a result, the residual metal ion concentration of the treated water was 0.031 ppm for copper and 0.
079ppm, lead 0.162ppm, zinc 0.060p
Although it was pm, the treated water was slightly black.

Treatment Example 7 The removing agent [I] of Treatment Example 1 (0.12% by weight of sodium alginate, 0.88% by weight of ferrous sulfate heptahydrate) was added to actual wastewater containing 444 ppm of copper and 448 ppm of nickel.
(Including) to a pH of 10 and stirred for 10 minutes,
Solid-liquid separation was performed. Table 1 shows the residual metal concentration of the treated water.

[0029]

[Table 1]

Treatment Example 8 (Comparative Example) An experiment was conducted in the same manner as in Treatment Example 7 except that 2800 ppm of calcium hydroxide was added instead of the removing agent [I]. As a result, the residual metal concentration was 0.25 pp of copper.
m, and nickel was 0.31 ppm.

Treatment Example 9 To the actual wastewater containing 50 ppm of copper, the removing agent [I] of Treatment Example 1 was added to adjust the pH to 10, and after stirring for 10 minutes,
Solid-liquid separation was performed. Table 2 shows the residual metal concentration of the treated water.

[0032]

[Table 2]

Treatment Example 10 (Comparative Example) An experiment was conducted in the same manner as in Treatment Example 9 except that 2000 ppm of calcium hydroxide was added instead of the removing agent [I]. As a result, the residual copper concentration was 0.11 ppm.

[0034]

According to the present invention, it is possible to efficiently remove heavy metals contained in water to be treated containing various dissolved heavy metals with a high removal rate and a reduced sludge generation amount.

─────────────────────────────────────────────────── ─── Continuation of front page (73) Patent holder 597126848 Shinji Wada 4-18-9-101 Togashira, Toride-shi, Ibaraki (73) Patent holder 000005979 Mitsubishi Corporation 2-3-6 Marunouchi, Chiyoda-ku, Tokyo (74) The above three agents 100074505 Patent Attorney Toshiaki Ikeura (72) Inventor Kenji Tatsumi 5-518-304 Matsushiro Tsukuba City, Ibaraki Prefecture (72) Shinji Wada 4-15-18-302 Togashira, Toride City, Ibaraki Prefecture (72) Inventor Yasuhiro Yukawa 5-16-14 Sakasedai, Takarazuka City, Hyogo Prefecture (56) References JP-A-53-34624 (JP, A) JP-A-10-34163 (JP, A) JP-A-61- 274792 (JP, A) JP 54-22953 (JP, A) Special Table 58-500358 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C02F 1 / 56,1 / 62

Claims (11)

(57) [Claims] 1. A process for removing dissolved heavy metal ions contained in water, in the aqueous, anion-containing hydrophilic polymeric substance flour powder-like or polymeric material ing of a mixture of sodium hydroxide non Aqueous liquid heavy metal a contained in dissolved form
A method for removing heavy metal ions, which comprises injecting an on-removing agent and dispersing the polymer substance in the removing agent without dissolving it in water to insolubilize dissolved heavy metal ions contained in the water. 2. The method of claim 1 wherein said mixture contains a harmless polyvalent metal compound. 3. The method according to claim 2, wherein the harmless polyvalent metal compound is ferrous sulfate. 4. The pH of the water is adjusted to 7 to 7 after the removal agent is added.
The method according to claim 1, wherein the range is adjusted to 12. 5. A coagulant is added to the water.
Either way. 6. The hydrophilic polymer substance containing an anion group,
The method according to claim 1, which comprises (i) alginic acid or a salt thereof, or (ii) a mixture of alginic acid or a salt thereof and another anionic group-containing hydrophilic polymer substance. 7. A removing agent for removing dissolved heavy metal ions contained in the water, Ri Do from a mixture of an anionic group-containing hydrophilic polymeric substance with sodium hydroxide, powdered
Or an aqueous liquid containing the polymer substance in a non-dissolved state, or
The polymeric substance is insoluble when the remover is put into water.
Heavy metal ion removal agent characterized der Rukoto those present in sexual state. 8. The heavy metal ion removing agent according to claim 7, wherein the mixture contains a harmless polyvalent metal compound. 9. The heavy metal ion removing agent according to claim 8, wherein the harmless polyvalent metal compound is ferrous sulfate. 10. The heavy metal ion removing agent according to claim 7, which further comprises an aggregating agent. 11. The hydrophilic polymer substance containing an anion group comprises (i) alginic acid or a salt thereof or (ii) a mixture of alginic acid or a salt thereof and another hydrophilic polymer substance containing an anion group. The heavy metal ion removal agent in any one of 10-10.