JP3278754B2 - Adsorbent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention provides a material for adsorbing heavy metal ions and phosphate ions in water and sewage and adsorbing and removing heavy metals in river water, mine wastewater and industrial wastewater.

[0002]

2. Description of the Related Art Conventionally, methods for recovering heavy metals from mine wastewater and industrial wastewater include oxidation, reduction, biological treatment, and the like.
A method of recovering as a sulfide or as a hydroxide by neutralization has been employed. However, in recent years, the sophistication of wastewater treatment has been required, and as a secondary treatment and a tertiary treatment, a method of removing and adsorbing with ion exchange resin, activated carbon, bone charcoal, etc. has been proposed. The problem is that it is expensive. In recent years, eutrophication of rivers and lakes has been regarded as a problem, and removal of phosphorus and nitrogen by tertiary treatment has been demanded, and an economical adsorbent has been desired.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide an inexpensive adsorbent for adsorbing heavy metal ions and phosphate ions in water.

[0004]

SUMMARY OF THE INVENTION Heavy metals according to the present invention
Adsorbents, characterized in that the added granulated and dried binder into a single particle or are formed of a calcium carbonate having a pore diameter 1 to 10 [mu] m, or powder the calcium carbonate And

[0005] Limestone, which is a raw material of calcium carbonate satisfying the above conditions, is often produced in Southeast Asia. The present inventors have tried to use limestone and dolomite as an adsorbent for heavy metal ions and phosphate ions. The inventors have found that soft limestone produced (hereinafter referred to as soft limestone) has much better adsorption of heavy metal ions and phosphate ions than ordinary limestone, and have completed the present invention. When this soft limestone is observed with an electron microscope, calcium carbonate particles having a diameter of 0.5 to 50 μm exist in a single particle state or in a lightly aggregated state, and individual calcium carbonate particles having a diameter of 2 μm or more (single particles) One particle) has pores having a diameter of 1 to 10 μm. The origin of the vacancies is not clear.

[0006] This soft limestone is not a hard one usually produced in Japan from the Paleozoic Carboniferous to the Mesozoic, but a shallow marine calcareous sediment formed after the Cenozoic. Some are porous and have a water absorption of as much as 20%. In addition, since the degree of agglomeration is light, it is soft, has no corners, is rounded, and can be easily dispersed into single particles. The chemical composition is close to pure calcium carbonate and contains slight amounts of magnesium, silica, iron, aluminum and the like as impurities. On the other hand, such vacancies do not exist in single particles of domestic limestone, for example, kudzu limestone (dolomite) and Okinawan limestone (coral).

[0007] This soft limestone is crushed and sieved to a predetermined particle size, and it is possible to use it as it is in the present invention. Are better.

From the viewpoint of use, it is convenient to granulate and dry the above calcium carbonate powder using a binder. A binder obtained by adding a binder to the calcium carbonate powder and granulating and drying the powder was prepared, and the adsorption properties of heavy metals were compared. As a result, the powder showed much better adsorption ability than ordinary limestone having the same particle diameter.

The binder used in the granulation includes starch, sodium alginate, gum arabic, casein,
It is possible to use hydrophilic binders such as gelatin, methyl cellulose, polyvinyl alcohol, sodium silicate and glycerin. The granulation method may be any of rolling granulation, press granulation, spray granulation and the like.

With the adsorbent of the present invention, all general heavy metal ions can be adsorbed, and the ability to adsorb phosphate ions is superior to ordinary limestone. In addition, if it is used as a water treatment material for waterworks, the effect of replenishing calcium can be expected. The adsorbent of the present invention is superior to ion exchange resins in that it can be adsorbed and removed even when the ion concentration range is wide. Also, it can be used in combination with an aggregating material.

[0011]

[Example 1] Indonesian "soft limestone"
Was crushed with a jaw crusher to adjust the particle size to a range of 2 to 5 mm. In addition, as Comparative Example 1, a limestone produced from kudzu was adjusted to the same particle size. This was filled in a column of a glass tube, and a cadmium chloride solution having a concentration of 100 ppm was passed through the column at a rate of 10 ml / min, and the cadmium concentration of the effluent after 8 hours was measured. As a result, 4 ppm for soft limestone and 8 for kuzumi limestone
It was 7 ppm.

[0012]

[Example 2] Indonesian "soft limestone"
Crushed to a powder having a particle size of 600 μm or less, added with 3% of polyvinyl alcohol and water, tumbled and granulated, and then dried.
A granulated product having a particle size of 2 to 5 mm was prepared. Comparative Examples 2 and 3
Kuzu produced limestone and Okinawa coral fossil limestone were processed in the same manner to produce granulated products. These were packed in a column in the same manner as in Example 1, a 100 ppm cuprous chloride solution was fed at a rate of 5 ml / min, and the copper ion concentration in the effluent after 8 hours and 24 hours was measured. The results were as shown in Table 1.

[Table 1]

[0013]

As shown in Examples 1 and 2, the adsorbent of the present invention has a high ability to adsorb heavy metals, is inexpensive and easily available, and is therefore suitable for treating mine wastewater, purifying rivers and lakes. Can be used as an inexpensive water treatment material.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B01J 20/00-20/34 C01F 11/18 C02F 1/58 C02F 1/62

Claims (2)

(57) [Claims] 1. A heavy metal adsorbent comprising calcium carbonate having pores of 1 to 10 μm in diameter in a single particle . 2. A heavy metal adsorbent, which is obtained by adding a binder to calcium carbonate powder having pores having a diameter of 1 to 10 μm in a single particle, granulating and drying the powder.