X Международная студенческая научная конференция Студенческий научный форум - 2018

Iron is very popular in the human society for a long time. It is a common olive oil in nature. This iron accounts for 4.2 percent of the Earth's crust. Among all the metals, iron has a huge role in the national economy. Production of ferrous metals, ie cast iron and steel, is one of the leading positions in the national economy development plan. In this regard, the abundance of iron residues is being developed. Currently, one of the most simple, effective and efficient methods of waste removal is to use other waste products [1-2].

Conducting research with the use of fine powders, because of the high degree of purification properties of fine metal than large powders. It is based on the properties of the two valence ions of iron, which are studied by the method of reducing the chromium six valence ions to three valents.

Fe^{2 +} ions are capable of reducing the Cr^{6 +} ion to the Cr^{3 +} ion in chromate and dichromate solution and deposition of Fe (CrO₂₎₂ precipitate:

Cr₂O₇-² + 6Fe₂ ++ 14H + → 6Fe^{3 +}+ 2Cr^{3 +}+ 7H₂O (1)

2Fe^{2 +}+ nH₂O + Cr₂O₇² + 4OH^- + 4e-→2Fe (CrO₂₎₂ + 2 (n + 1) H₂O + 4O₂^- (3)

Iron and aluminum powder were obtained to investigate the effect of drain water on the level of chromium (VI) ions. The greatest degree of purification was detected in iron powders in 10 minutes, as the concentration of iron (II) in the solution increased, the degree of purification from chromium (VI) ions increased to 98%. The degree of purification of contaminated water from chromium (VI) ions in aluminum powder reached 65% in 10 minutes

The iron metals, in acid solution dissolve intensively to form iron (II) hydroxide (coagulant):

Fe⁰ + 2H₂O - 2e ^- Fe(OH)₂ + 2H⁺ (1)

The resulting colloidal iron (II) hydroxide restores chromium (VI) to chromium (III) and further co-precipitation of chromium occurs with iron (III) hydroxide formed by the reactions (2):

Cr₂O₇^2- + 6 Fe(OH)₂ + 7H₂O2Cr(OH)₃ + 6Fe(OH)₃ + 2OH^- (2)

2Cr₂O₇^2-+ 2Fe³⁺+ nH₂O+4OH^-+2e^-2Fe(CrO₂₎₂+2 (n+1) H₂O+4O₂ (3)

CONCLUSIONS

Data on the treatment of contaminated waste water with chromium (VI) ions using industrial wastes have been studied little. We used iron and relatively aluminum residues which are only industrial wastes for the treatment of waste water containing chrome ions. In fact, this method has advantages over many other methods:

1. Dewatering method does not require any electrical energy, reagents or complex equipment.

4. The most important is to find the remnants of the iron found in experiments anywhere.

And these advantages, how much will this method cost and how much it will benefit. That is why this method can be considered as a very effective, very convenient method in difficult economic conditions.

REFERENCES

A.S. USSR Ν 1785519 Method for purification of chrome-containing wastewater. Opubl. 30.12.92. Bullet No. 48

Vorobyova OM, Ippolitova EA, Nemkova OG, Dunaev KM Workshop on Inorganic Chemistry, Moscow, 1976, 298

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