JPS59190227A - Reduction of fe3+ by contact of different metals - Google Patents

Abstract

PURPOSE:In reducing Fe<3+> in an acidic aqueous solution using Fe or a metal baser than Fe, to reduce Fe<3+> efficiently and rapidly, by bringing a metal such as Pb, Ag, or Au except Fe and Os of VIII group or Sn into contact with the metal. CONSTITUTION:Fe<3+> ion in an acidic aqueous solution is reduced by using one or both of Fe and a metal such as Zn, Al, Mn, or Mg baser than Fe. In the operation, one or more of Pt, Pd, Rh, Ru, Ir, Pb, Sn, Ag, Au, Ni, and Co or its alloy as a metal catalyst is brought into contact with the metal. The metal and the metal catalyst can be used in various kinds of state such as powder, platy state, etc.

Description

[Detailed Description of the Invention] The present invention provides a method for efficiently reducing Fe ions in an aqueous solution by bringing different metals into contact with each other as a catalyst when using iron or a gold film that is stronger than iron. It is related to.

] When PaC ions are converted to 1 illt using a metal Δ1 which is less noble than iron in an acidic aqueous solution, the following reaction generally occurs.

,n]('c 1-ゞ"-°1°+M"-゛(1
,)(・Roy−+M=u Ij2+
Mn+ --(2), that is, if only the reaction (1) occurs, no gaseous hydrogen is generated, and the efficiency is 100%.
It is possible to reduce Fe to Fc. However, in general, the reaction (2) also occurs, and the more gaseous hydrogen is generated, the more hydrogen ions are generated, that is, the pH increases, and the reduction rate and the reduction efficiency are also lowered.

Conventionally, as a method for reducing Fe 2 ions, a method using a metal that is more base than mercury and iron and forms an amalgam with mercury has been used, particularly in chemical analysis. Since mercury or mercury amalgam has a very high hydrogen overvoltage and is difficult to generate hydrogen, the above-mentioned reaction (2) hardly occurs, and therefore the reaction (1) is the main one, making it a very good method in terms of reduction efficiency. be. However, the speed of the reduction reaction is very slow, and it is not a desirable method from the viewpoint of industrially reducing a large amount of Fe 2 ions.

In the case of reduction using a metal M which is more basic than the other method, the Fc ions generated by the Fe3+ ion and the M1 used are
It is precipitated as metallic iron on the metal surface by the following reaction.

2+ nFe + '2M = nFe + 2
(3) When reducing with iron or a metal less noble than iron, the reduction reaction on the iron surface is important in any case.

When iron is used to reduce Fc in an acidic aqueous solution, the reduction rate of iron per unit surface area generally decreases. Similarly, when a metal less noble than iron is used, the reaction is mainly carried out on the iron surface, and the reduction reaction rate decreases with time. This is thought to be because the iron surface after disintegration is very active and strong, and some kind of protective film (possibly a j.1 feminized film) is immediately formed on it.

In order to avoid this situation, the present inventors used a metal catalyst that is nobler in potential than iron and has stronger reduction activity than Fe.
When it comes into contact with the metal M or the metal M mentioned above, the dissolution of gold 1 door into ions occurs on the surface of Fe or the metal M, and the gold 1(j
It was thought that the ○ formed by the dissolution of the '4 ion would be transferred onto the metal catalyst surface, where the reduction reaction of Fe and gaseous hydrogen generation would be carried out. With this method, it is expected that reduction can be carried out on a highly active catalytic metal surface without reducing the reaction activity of the surface to be reduced as described above. From the point of view of the catalyst, it is undesirable for metal components to dissolve during the reaction. - Gaseous hydrogen may also be generated, so it is necessary to suppress this reaction as much as possible. As a result of various studies while keeping the above points in mind, Pi, Pd, and Ru were selected.

RIB, Ir, Pb, Sn, A, g, Au and Ni, C
o's] l! It has been found that when 1S or several kinds or alloys thereof are used as a catalytic catalyst, the reduction activity is always strong, the reduction reaction rate is fast, gaseous hydrogen is generated little, and reduction can be carried out efficiently.

In addition to iron, iron and/or metals baser than iron used in the present invention include metals such as zinc, aluminum cum, manganese, and magnesium, and are in the form of powder, granules,
It can be in the form of cotton, chips, plates, etc., while Pi, Pd as the metal catalyst in contact with this can be used.
,]]1-h, 11. u, Ir, Pb.

S11. Ag, Au, Ni, Co, or their alloys can also be used in various forms such as powder, granules, cotton, and plate. It is also possible to bring different metals into good contact with each other (it is also possible to further change the shape of the Qp medium to make it into various shapes such as a wire mesh, a spiral, and a cage (!). Plated metals can also be used.Generally speaking, the larger the surface area of the metal to be dissolved and the catalyst metal, the higher the reaction rate and the better the reduction efficiency. The shape should be selected with this in mind.

The present invention is particularly applicable to cases where the production of Fe in an iron-based plating solution reduces the electrodeposition efficiency and adversely affects the properties of the plating film, and in this case, the catalyst of the present invention is used. Fe can be reduced efficiently and quickly.

Furthermore, the present invention can be widely applied to other analyzes and to the analysis of metal ions.

Example 1 1・'e ion 56! / pH 1,0 including i
Fe ions in a sulfuric acid acidic aqueous solution of Suisho 500C were reduced to metals iron and zinc using a metal catalyst.

The amount of aqueous solution is 100cc, and the Fe contained in this liquid is
5.6. The amount of iron required to theoretically reduce i' to 100% is 2.8! Reduction was carried out using 3.21 as zinc until the iron or ready lead completely disappeared.≦After the reaction, the remaining Fe ions were analyzed and the reduction efficiency was calculated.

On the other hand, a similar experiment was conducted on a system in which a catalyst and various metals were brought into contact with Fc and Zn1.The results obtained are shown in Table 1. From the table, it can be seen that although mercury amalgam has good reduction efficiency, the reaction rate is very slow, and it is not practical in an industrial sense. On the other hand, it can be considered that the catalyst comes out
i, Cu, carbon + Mo accelerate the reaction time, but in terms of reduction efficiency, Pt, Pd of the present invention
, Au, Ni, Ag, Co etc.
I was called.

Table 1 Reduction of n'Ni50%-Co50% alloy 3+ Fe ions by metal dissolution Example 2 A water reservoir containing 3+ Fe 207//12 was treated using metal thrust particles (particle size 2 mm to 3 rnm). A comparison was made between the use of a platinum catalyst and the use of a platinum catalyst during reduction under manure conditions.

Aqueous solution composition Fc 20j;'/12 liquid-
Total 50012], 'c 60! /ノZn 80! /ll ll2So, acidic pH 1,2 temperature 50℃ reduction equipment
200mmψ circle [≦)-shaped reaction A11] 1 lead grain] 1
Passed at a flow rate of /sec.

For the platinum catalyst, a linear chip of mmψ×3 to 511i1# was prepared with a diameter of 10.5 mm. f' was added and reacted.

(The results obtained are shown in Table 2.

From Table 2, it can be seen that when a platinum catalyst is used, the sonic reaction rate increases by about 1, and the reduction efficiency also improves.1. can be tolerated,
.

Table 2: Reduction of 1・C by using a fluidized tank - − − 1゜ −

Claims (1)

[Claims] When reducing Fc ions in an acidic aqueous solution using V, and U/or a metal less noble than iron, P L ', P
d. Rh, 11. u, ■rj]l:+, Sn, Ag, Au,
An Fc reduction method by contact with different metals, characterized in that one or more of Ni, Co, or an alloy thereof is reduced in a state in which it is brought into contact with the metal.