Process for complete degradation of Methylene blue in wastewaters with high content thereof

Invenfia refer! to the procedures for the elimination of the dyes from the waste water, namely to a process of complete destruction of the methylene blue in the residual waters with its increased containment.

It is known that methylene blue causes! oxidation of bivalent iron from hemoglobin !, transfoimiandu-1 m trivalent iron, ie! hemoglobin is transformed! in methemoglobin, the formation of which has a negative impact on human health [1].

The process of photodegradation of methylene blue is known, as a catalyst being used a layer of TiO2 nanoparticles [2].

The disadvantage of this procedure is! in the fact that! to obtain the layer of TiO2 nanoparticles is used! titanizopropoxide: isopropanol: acetylaceton! : ap! : acetic acid with a molecular ratio of 18: 3: 1.1: 0.05, which is expensive. In the work it is not mentioned! the products of photocatalytic oxidation of methylene blue. The process proceeds with the destruction of only 50% of the initial quantity! (40 pmol / l) of methylene blue. This result is obtained m following the recirculation of the same solution 5 times with the duration of the process of 14 min. The installation for the photocatalytic oxidation process! it is quite sophisticated!

The process of degradation of methylene blue by catalytic oxidation is known! wet! on carbon nanotubes impregnated with Fe and Cu [3].

Carbon nanotubes used as a support for the preparation of iron and copper catalysts are obtained by chemical deposition! of acetylene / nitrogen vapors, using Fe / AhOs as catalyst in the given process. Material! what a const! of iron nanotubes and aluminum oxide are treated! with sulfuric acid to obtain nanotubes with 97% carbon purity.

The chemistry of the nanotube surface is changing! by introducing carboxylic groups, by treatment with 5M HNO3 for 3 hours, subsequently being sprayed with NO3 ions and dried at 110 ° C, up to mass; constant!. Further the nanotubes thus modified are treated! with Fe (NO3) 3 · 9H2O and Cu (NO₃> 2 · 3H2O in aqueous solutions.

Following the catalytic oxidation process! The following products are obtained from Methylene Blue:

butan-2-amine !; aridion; benzylidene; benzacetic acid; benzonitrile.

The disadvantage of this procedure is! in the fact that! m the catalytic oxidation process! in particular, benzonitrile is obtained, which, following the metabolic process, forms in living organisms! CN ion ", what blocks it! many fermenfi, including cytochrome oxidase. As a result, the liver loses the ability to assimilate oxygen - a fact that leads to hypoxia of the living tissues of living organisms.

The closest! solution is the process of purification of methylene blue wastewater, which includes catalytic oxidation by oxygen bubbling of water at 30 ... 50^AC and at the gas pressure of 2 atm for 2 hours, in the presence of the active charcoal obtained from walnut shells, with a confinement of functional groups of basic character with the concentration of 0.555 mg-equiv / g and the surface of the mesopores of 410 m2 / g [4].

The disadvantage of this procedure is! in the fact that! in such conditions the com pick (up to sulfafi, free nitrogen, carbon dioxide and water!) destruction of methylene blue does not take place. This results from the comparison of the proton resonance spectra! magnetic! nuclear! of methylene blue (fig. 1) and of the oxidation products of this dye (fig. 2).

The problem that the invention solves is const! in the complete destruction of the blue dye of Methylene, the residual metals with increased confinement of them with the formation of simple products (sulfafi, free nitrogen, carbon dioxide and water!), which are not toxic pollutants.

The process of complete destruction of methylene blue in wastewater with increased containment includes catalytic oxidation! of methylene blue at its concentration of at least 120 mg / L by oxygen bubbling at

5O ... 7O ° C and the gas pressure of 2 atm, for 2 ... 3 hours at the same time! m catalyst quality is used! activated charcoal, obtained from walnut shells! with a content of functional groups with a basic character of 0,555 mg-echiv./g and the surface of the mesopores of 410 m²/ g, the ratio between catalyst and methylene blue being 50: 3.

MD 484 Z 2012.09.30

The result is complete destruction of the dye with the formation of simple products: sulphates, free nitrogen, carbon dioxide and water, which are non-toxic.

It was found that when the concentration of methylene blue in the system increases, ie at 120 mg / L, the catalytic oxidation process unpredictably results in a higher yield and leads to the complete destruction of methylene blue.

The result is due to the fact that the basic functional groups on the surface of CAN-8 activated carbon in the presence of dissolved oxygen generate the formation of the OH 'radical, which under the conditions of the experiment completely oxidizes the dye. The process can be used for water treatment, when after storage and natural evaporation the concentration of methylene blue reaches the critical concentration claimed, or in the case of massive spills.

CAN-8 activated charcoal was obtained in two stages: first - obtaining carbonized raw material (unfractionated walnut shells), second - water vapor activation of the obtained carbonized.

The table shows the physico-chemical parameters of the active carbon CAN-8.

Table

<td>Sample of coal active</td><td>Concentration of functional groups with basic character, mg- equiv./g</td><td>Concentration of functional groups with acidic character, mg- equiv./g</td><td>Specific surface area of ​​activated carbon, m²/ g</td><td>The surface of the mesopores of activated carbon, Sme, m²/ g</td><td>Activated charcoal iodine index, mg Ii / g</td><td>The Methylene Blue Index of Carbo- of the active nut, mg AM / g</td>

<td>CAN-8</td><td> 0,555</td><td> 0,139</td><td> 940</td><td> 410</td><td> 1095,6</td><td> 300,3</td>

At the dye concentration of 120 mg / L in the solution, hemimics are formed, ie planar associates, which at the interface "activated carbon - solution" interact with the OH radical in a higher yield than when the concentration of methylene blue is 20 mg / L , so that the catalytic oxidation process of this dye proceeds with the formation of simple substances - S, N2, CO2 and H2O.

The process of catalytic destruction of methylene blue was controlled using the chromatomasspectrometric method.

The obtained results are presented in fig. 3.

- chromatogram, zero sample (activated carbon, demineralized water, oxygen bubbling at 50 ° C);

2 - chromatogram of the catalytic oxidation products of methylene blue according to the proposed process.

The analysis of the spectra presented in fig. 3 allows us to conclude that all the bands of methylene blue disappear in the oxidation process. The chromatogram of the oxidation products of methylene blue under the conditions of the nearest solution is shown in fig. 4.

The mechanism of the oxidation process of the given dye is explained by the participation of the basic functional groups and by the fact that in the process of oxygen bubbling of the solution containing Methylene blue (Co = 120 mg / L) on the surface of the active charcoal CAN-8 (at the interface) they absorb planar associations (hemimics) of dye and oxygen molecules. Thus at the interface there is a potential difference. (Стрелко В.В., Картель Н.Т.,

Клименко Л.А., Каздобин К.А. Электрохимические свойства углеродных гемосорбентов. П.П.Х., TLX, №6, 1987, с.1257-1260).

Following this process at the interface, the ОН radical is formed, which has a high oxidation potential (2.7 V), which, under the conditions of the experiment, completely oxidizes methylene blue.

Examples of embodiment of the invention

Example 1

In two reactors with magnetic stirrers and a water jacket, 200 mg CAN-8 activated carbon with 0.6 to 0.8 mm phosphate and 100 mL of methylene blue solution with 120 mg concentration / IT. The reactor solutions are heated to 50 ° C. Oxygen is bubbled through the solution in the first reactor and through the solution

MD 484 Z 2012.09.30 from the second reactor nitrogen is bubbled to remove the adsorption composition. The gas pressure being 2 atm. After 3 hours of boiling, the activated charcoal separates from the solution. The solution is subjected to vaporization in the oven at 100 ° C. The obtained product is dissolved in clean methanol and subsequently the chromatogram is measured at the apparatus.

Agilent 5973. It was established that in the solution by which the nitrogen nitrogen was bubbled, the concentration of methylene blue was partially reduced, due to adsorption, and in the solution by which oxygen was bubbled, the complete destruction of the methylene blue occurred.

Example 2

The conditions of Example 1 are repeated, except that the temperature of the solutions was

60 ° C. The complete destruction of methylene blue occurred.

Example 3

The conditions of Example 1 are repeated, except that the temperature of the solutions was 70 ° C. The complete destruction of methylene blue occurred.

(56) Bibliographic references cited in the description:

1. CA Куценко. Основы токсикологии. Санкт-Петербург, 2002

2. Chin Mei Ling, Abdul Rahman Mohamed and Subhash Bhatia. Photodegradation of methylene blue dye in aqueous stream using immobilized TiO2 film catalyst: sythesis, characterization and activity studies. Jurnal Technologi, 40 (F), Jun, 2004, pp. 91-103.

3. A. Rodrigues, G. Ovejero, M. Mestanza, V. Callejo, I. Garcia. Degradation of Methylene Blue by Catalyst Wer Air Oxidation with Fe and Cu Catalyst Supported on Multi-Chemical Engineering Transaction, V 17, 2009, pp. 145-151

4. MD 4008 Bl 2010.01.31 (57) Claims: