The catalytic properties of iron-containing layered aluminosilicate in the photooxidation of the dye "Methyl green"

The catalytic properties of iron-containing layered aluminosilicate in the photooxidation of the dye "Methyl green"

Shadrina O.A., Khankhasaeva S.Ts., Dashinamzhilova E.Ts., Bashkueva M.N.

Baikal Institute of Nature Management SB RAS

Buryat State University

Department of inorganic and organic chemistry, Ulan-Ude, Russia

Currently intensive researches on the purification of water and air are conducted in many countries. The most effective ways of wastewater treatment from organic pollutants are the "advanced oxidation processes", in which the oxidation of organic substances is a highly active oxygen-containing particles or radicals generated from H₂O₂, O₂ and O₃. These technologies include Fenton and photo-Fenton ferrum-peroxide system (Fe²⁺/H₂O₂, Fe³⁺/H₂O₂, Fe³⁺/(H₂O₂,UV)), with which is held deep oxidation of organic compounds to carbon dioxide, water and inorganic ions [1].

The purpose of this work is to study the catalytic properties of iron-containing layered aluminosilicate in the photooxidation of the dye "Methyl green".

The objectives of the study are:

1. To analyze literature data on photocatalytic oxidation of organic compounds.

2. To get iron-containing materials from a natural layered aluminosilicate is montmorillonite.

3. To determine their iron content and specific surface area.

4. To study the catalytic properties of the materials in the photooxidation of dyes in aqueous solutions.

5. To investigate the influence of physicochemical parameters on the photo-oxidation of the dye "Methyl green" such as the loading of the catalyst, the molar ratio of hydrogen peroxide and the dye.

6. To set the effect of photo-oxidation on the content of total organic carbon (TOC).

7. To calculate the quantum yield of the reaction

Object of the study: clay mineral montmorillonite occurrence of Buryatia.

Methods of the study: the photometric method for the determination of the mass concentration of ions Fe²⁺/Fe³⁺on-fenantrolina (KFK-2), low-temperature adsorption of nitrogen, UV-Vis spectrophotometry (Agilent 8453), determination of total organic carbon (ТОС analyzer Shimadzu TOC-L CSN).

In this work the photocatalytic properties of materials obtained by fixing iron oxide nanoparticles between aluminosilicate layers of a clay mineral montmorillonite, having a chemical composition (wt.%): SiO₂ - 65.6, Al₂O₃ - 15.4, Fe₂O₃ - 2.0, FeO - 0.08, MnO ‹0.01, MgO - 1.42, CaO - 1.18, Na₂O - 0.02, K₂O - 0.06, P₂O₅ ‹0.03, TiO₂ - 0.16, Н2О - 14.31 [2]. The iron content of the materials was measured by the photometric methods by reaction with o-phenanthroline, it was 48.3 for material (I), 41.7 mg/g for the material (II). The specific surface area of ​​the material was calculated by the method of low-temperature adsorption nitrogen in the Termosorb LP (Katakon, Novosibirsk, Russia) and was equal to 107 (I), 96 (II) m²/g. The testing of catalytic properties of materials in oxidation reactions of dyes (Methyl green, Methylene blue, Bromphenol blue) of hydrogen peroxide in aqueous solutions were used to determine the catalytic activity. Two ultraviolet lamps T8 UVC 15W, 220V, 50Hz, λmax = 254 nm were used to irradiate solutions [3]. The efficiency of photo-oxidation of dyes were established from the degree of decolorization of their solutions in hydrogen peroxide and catalysts. The introduction of the catalyst in the reaction mixture and UV-irradiation caused an increase in the efficiency of 1.2 times for BPhB, 1.5 times for MG and 1.3 times for MB compared to non-catalytic reaction. For further study we used the dye MG, in the oxidation which was observed the highest catalytic effect in the addition of FeММ. The table shows the results of experiments on the study of activity and stability of catalysts in the oxidation of dye MG.

The study of the activity and stability of catalysts in the oxidation of dye «Methyl green»

The catalyst 1 is the most active and stable from the received materials. It is characterized by the greatest iron content (52.5 mg/g) and minimum leaching (0.12%), and also has a large specific surface area (107 m²/g). The efficiency of UV oxidation dye MG amounted to 90.5% in the presence of this catalyst. The results indicate a promising that the development of heterogeneous photographic systems of the purification of wastewater from dyes using Fe-containing catalysts based on clay minerals [3].

Conclusion:

1. Two samples of the iron-containing material from a natural layered aluminosilicate (montmorillonite) with an iron content of 40 mg/g and 52.5 mg/g, a specific surface area of 107 m²/g and 96 m²/g to received.

2. It is shown that the most active and stable catalyst in the photooxidation of the dye MG is the material that contains the largest amounts of iron which has the largest specific surface.

3. The optimal content of the catalyst and the optimum ratio of concentrations of the hydrogen peroxide and dye MG were obtained, at which the efficiency of oxidation is 100%.

4. The content of total organic carbon (TOC) after the oxidation reaction was determined.

5. The quantum yield of the reaction of photo-oxidation was calculated.

References:

1. Fenton H. J. H. Oxidation of tartaric acid in presence of iron / H. J. H. Fenton. – J. Chem. Soc., Trans. 65, 1894. - P. 899-911

2. Дашинамжилова Э.Ц. Влияние условий приготовления Fe- монтмориллонитов на их каталитическую активность в окислении фенола в водных растворах/ Дашинамжилова Э.Ц., Ханхасаева С.Ц. // Журнал прикладной химии – 2012.- Т. 58, Вып. 3 – С.500-505.

3. Рэнби Б. Фотодеструкция. Фотоокисление. Фотостабилизация полимеров / Б. Рэнби, Я. Рабек, Под редакцией Н. М. Эмануэля. // Москва: Издательство «Мир», 1978. - 676 с.