JP2009254932A - Heavy metal treating agent and method of treating heavy metal-contaminated matter using the agent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that, though having a capability of adsorbing heavy metals, conventional manganese dioxide has a low heavy metal adsorption capacity and is required in large amounts for treatment of heavy metal-contaminated materials. <P>SOLUTION: δ-Manganese dioxide whose potential (vs. Hg/HgO, 40%KOH), is ≥275 mV has an excellent heavy metal treating capability and enables heavy metals to be treated only in small amounts of the dioxide used. The δ-manganese dioxide is produced by reacting a permanganate with manganese sulfate in an Mn<SP>2+</SP>/Mn<SP>7+</SP>molar ratio of <1.5. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is a solid waste containing heavy metal, for example, incinerated ash discharged from a garbage incineration plant, soil contaminated with heavy metal, sludge generated after wastewater treatment, lead contained in wastewater discharged from a factory, The present invention relates to a heavy metal treating agent capable of easily and efficiently treating harmful heavy metals such as cadmium, copper, zinc, nickel, mercury, arsenic, selenium and thallium, and a method for treating heavy metal contaminants.

  Manganese dioxide oxides are largely classified in terms of crystal structure such as α, β, γ, η, δ, and ε, and it is known to use these to detoxify various heavy metals contained in wastewater. . In particular, δ-type manganese dioxide having a layer structure is effective because heavy metal ions are immobilized between layers by ion exchange or adsorption.

  For example, heavy metal adsorption characteristics using δ-type manganese dioxide have been reported to have an affinity for cationic elements such as alkali metals, alkaline earth metals, and transition metals (see Non-Patent Document 1). Furthermore, the adsorption property of phosphate in a system in which an alkaline earth metal or transition metal ion is present has also been reported (see Non-Patent Document 2). Furthermore, a heavy metal treating agent containing δ-type manganese dioxide having a weight loss of 6% by weight or more in a temperature range of 120 ° C. to 400 ° C. has been reported (see Patent Document 1).

δ-type manganese dioxide is generally chemically synthesized. For example, it is synthesized by dropping an aqueous solution of manganese chloride into an alkaline solution of potassium permanganate by oxidation of Mn ²⁺ or reduction of Mn ⁷⁺ (Non-patent document 1).

  However, although δ-type manganese dioxide synthesized by the conventional method has a certain amount of heavy metal treatment capability, it has not been able to perform as a treatment agent applicable to water pollution prevention methods and waste cleaning methods, which have recently been tightened by regulations. A large amount of drug was required.

JP2008-18312A EFFLENT AND WATER TREATMENT JOURNAL MAY 1981 201-203 Water. Research. Vol20, No4 471-475 1986

  The present invention provides a heavy metal treating agent and a method for treating heavy metal pollutants that can incinerate incinerated ash, waste water, and the like containing heavy metal pollutants to an environmental standard or higher.

  As a result of intensive studies on manganese dioxide having excellent heavy metal treatment performance, the present inventors have found that δ-type manganese dioxide having a potential of 275 mV or more in a 40% KOH aqueous solution with reference to an Hg / HgO reference electrode has a heavy metal treatment ability. The inventors have found that the present invention is particularly excellent and have completed the present invention.

  If the δ-type manganese dioxide of the present invention is used as a heavy metal treating agent, it is possible to treat heavy metals with a small amount of adsorbent. In addition, the total amount of waste can be reduced by reducing the amount of medicine used.

  Hereinafter, the present invention will be described in detail.

  The δ-type manganese dioxide, which is the heavy metal treating agent of the present invention, has a potential (vs. Hg / HgO. 40% KOH, that is, 9 N (N) KOH) of 275 mV or more.

  The potential as used in the present invention is measured using a mercury / mercury oxide electrode which is common in the field of electrochemistry as a standard electrode. For example, 2 g of manganese dioxide powder and 0.6 g of graphite can be kneaded with 9N-KOH, and Hg / HgO can be measured in 9N-KOH as a reference electrode.

  When the potential is less than 275 mV, the processing performance of heavy metal, that is, the adsorption capacity is lowered. The potential is preferably 275 V or higher, particularly 280 V or higher, and more preferably 290 V or higher.

  The crystal structure of manganese dioxide used in the heavy metal treating agent of the present invention is δ-type manganese dioxide.

The manufacturing method of the manganese dioxide used for the heavy metal processing agent of this invention can be manufactured using a permanganate and Mn2 ⁺ salt, for example.

Conventionally, a general method for synthesizing δ-type manganese dioxide using permanganate and Mn ²⁺ salt is synthesized according to the following reaction formula, with a molar ratio of Mn ²⁺ / Mn ⁷⁺ at the time of synthesis being 1.5. ing.

一方、本発明の重金属処理剤の二酸化マンガンは過マンガン酸塩の組成比を大きくして、Ｍｎ^２＋／Ｍｎ^７＋のモル比を１．５未満とすることによって得られる。Ｍｎ^２＋／Ｍｎ^７＋のモル比はさらに１．３以下、さらに１以下、中でも０．６以下とすることが好ましい。

On the other hand, manganese dioxide of the heavy metal treating agent of the present invention can be obtained by increasing the composition ratio of permanganate so that the molar ratio of Mn ²⁺ / Mn ⁷⁺ is less than 1.5. The molar ratio of Mn ²⁺ / Mn ⁷⁺ is further 1.3 or less, further 1 or less, and preferably 0.6 or less.

  The heavy metal treating agent of the present invention can treat heavy metals by using it mixed with pollutants containing various heavy metals such as incineration ash or fly ash, soil, groundwater and wastewater.

  Heavy metals contained in various types of garbage are concentrated in the incineration ash. This is particularly noticeable in fly ash and molten fly ash, and many of the molten fly ash contain heavy metals such as lead in a percent order, and thus a detoxification treatment is required. Fly ash and molten fly ash are classified into alkaline fly ash, neutral fly ash, alkaline molten fly ash, neutral molten fly ash, etc., depending on the structure and operation method of the incinerator, and the type of garbage to be incinerated. It is known that the type and content of heavy metals contained in each type differ greatly, but the heavy metal treating agent of the present invention can be used for any type of fly ash. The ash can be rendered harmless by adding the heavy metal treating agent of the present invention and water and kneading.

  The heavy metal treating agent of the present invention is also effective for treating soil containing heavy metals, and can be rendered harmless by adding and kneading the heavy metal treating agent to soil containing heavy metals. If necessary, water can be further added and kneaded.

  The heavy metal treatment agent of the present invention can be used for treatment of waste water containing heavy metals. The heavy metal treatment agent is added to and mixed with waste water containing heavy metals, or the heavy metal treatment agent is added to a column or the like. It can be rendered harmless by passing wastewater that is filled and contaminated with heavy metals.

  The amount of heavy metal treating agent used for heavy metal pollutants varies depending on the heavy metal content in the pollutant and cannot be specified unconditionally. However, it is 0 for solid-type treated products that are difficult to mix, such as incineration ash and fly ash. 1 to 50 wt%, preferably 0.5 to 30 wt% can be exemplified. Moreover, it is preferable to mix 0.01-20 wt%, preferably 0.05-10 wt% with respect to the water-based processed material (drainage, groundwater) which is easy to disperse | distribute uniformly.

  Moreover, you may add and use another adjuvant in the range which does not impair the effect of this invention.

  The heavy metal treatment agent of the present invention can be highly detoxified by adding a small amount to a heavy metal contaminant, and the heavy metal element after treatment is completely fixed, so that extremely stable treatment without re-elution is possible. .

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Example 1
Potassium permanganate (KMnO ₄ ) having a concentration of 0.1 mol / L was dissolved in pure water, and 1 mol / L sulfuric acid was gradually added to prepare a solution. On the other hand, a solution in which sulfuric acid of 1 mol / L concentration was added to an aqueous solution in which manganese sulfate (MnSO ₄ .5H ₂ O) of 0.55 mol / L was dissolved was prepared, and the molar ratio of Mn ²⁺ / Mn ⁷⁺ at the time of preparation 227 mL of an aqueous manganese sulfate solution having a 1.25 of 1.25 was added dropwise to the aqueous permanganate solution and aged for 2 hours. The resulting product was filtered, washed with water and dried.

  The XRD measurement result of the obtained product is shown in FIG. The crystal structure was δ-type manganese dioxide. Further, after adding a small amount of 0.6 g of conductive agent graphite and 9N-KOH to 2 g of the obtained δ-type manganese dioxide and kneading, the potential was measured at room temperature using Hg / HgO as a reference electrode in 9N-KOH. The potential was 280 mV.

Example 2
Preparation was carried out except that 91 mL of the 0.55 mol / L manganese sulfate aqueous solution of Example 1 was taken and dropped into the potassium permanganate aqueous solution so that the charge Mn ²⁺ / Mn ⁷⁺ molar ratio at the time of synthesis was 0.5. Same as Example 1.

  The XRD measurement result of the obtained product is shown in FIG. The potential was 290 mV.

Comparative Example 1
Preparation was carried out except that 273 mL of the 0.55 mol / L manganese sulfate aqueous solution of Example 1 was taken and dropped into the potassium permanganate aqueous solution so that the charge Mn ²⁺ / Mn ⁷⁺ molar ratio at the time of synthesis was 1.5. Same as Example 1. As a result of measuring the potential based on Example 1, it showed 270 mV.

Comparative Example 2
364 mL of the 0.55 mol / L manganese sulfate aqueous solution of Example 1 was taken so that the charged Mn ²⁺ / Mn ⁷⁺ molar ratio at the time of synthesis was 2.0, and this was carried out except that it was dropped into the potassium permanganate aqueous solution. Same as Example 1. As a result of measuring the potential, it was 260 mV.

Comparative Example 3
In an aqueous solution containing manganese sulfate at a concentration of 0.6 mol / L and sulfuric acid at a concentration of 0.35 mol / L, electrolysis is performed on the titanium at a current density of 0.5 A / dm ² using titanium as the anode and carbon as the cathode. γ-type manganese dioxide was deposited.

  The potential of the obtained γ-type manganese dioxide was 300 mV.

(Test 1: Evaluation of heavy metal processing ability)
Using 20 mg of manganese dioxide obtained in Example 1, Example 2, Comparative Example 1, Comparative Example 2 and Comparative Example 3, 500 mL of a solution having an initial Pb concentration of 10 ppm and a pH of 7 was treated for 30 minutes. The residual Pb concentration was measured. The results are shown in Table 1.

  In the manganese dioxides of Example 1 and Example 2, the Pb residual concentration was 0.01 mg / L or less, but in Comparative Examples 1 to 3, the treatment performance was lowered.

XRD measurement diagram of δ-type manganese dioxide (Example 1, Example 2)

Claims (3)

A heavy metal treating agent comprising δ-type manganese dioxide having a potential (vs.Hg / HgO.40% KOH) of 275 mV or more. The method for producing δ manganese dioxide by the reaction of permanganate and manganese sulfate, wherein the molar ratio of Mn ²⁺ / Mn ⁷⁺ is less than 1.5. Method. The processing method of the heavy metal which adds the heavy metal processing agent of Claim 1 to any one of the incineration ash containing heavy metal, soil, groundwater, and wastewater.

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