Synthesis, characterization and application of molybdenum trioxide in photocatalysis of synthetic textile effluent

Silva, C. A. A.; Silva, C. F.; Matos, J. M. E.

doi:10.1590/0366-69132018643712341

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Articles • Cerâmica 64 (371) • Jul-Sep 2018 • https://doi.org/10.1590/0366-69132018643712341 copy

Synthesis, characterization and application of molybdenum trioxide in photocatalysis of synthetic textile effluent

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

In this study, the molybdenum trioxide (MoO₃) was synthetized by hydrothermal method with fixed temperature of 180 °C and different times of 1 and 6 h, followed by heat treatment for 6 and 12 h at 300, 450 and 600 ºC. The crystalline phase and structural properties of the sample were characterized by X-ray diffraction method. Vibrational behavior of chemical bonds was verified by infrared and Raman spectroscopies where the observed bands and peaks confirmed the formation of MoO₃. The scanning electron microscopy showed the microstructure formation of hexagonal (h-MoO₃) and orthorhombic (α-MoO₃) phases. Furthermore, diffuse reflectance spectroscopy measured the optical absorption properties and the energy gap values were estimated in the range from 2.74 to 3.33 eV from the Kubelka-Munk function. The oxides calcined at 600 ºC showed the best photocatalytic activity, degrading 50% of dye in 2 h of reaction.

Keywords:
synthetic effluent; photocatalysis; molybdenum trioxide

Tabela I Composição do efluente sintético.

Componente	Concentração (g.L^-1 )
Corante preto direto	0,10
Álcool polivinílico	0,50
NaCl	0,25
Na₂SO₄	0,75

Tabela II Valores de energia de band gap dos pós de MoO3.

Reação hidrotérmica	Calcinação	Band gap (eV)	Reação hidrotérmica	Calcinação	Band gap (eV)
180 ºC/1 h	300 ºC/6 h	3,10	180 ºC/6 h	300 ºC/6 h	3,33
	300 ºC/12 h	2,88		300 ºC/12 h	2,74
	450 ºC/6 h	3,09		450 ºC/6 h	3,00
	450 ºC/12 h	3,06		450 ºC/12 h	3,00
	600 ºC/6 h	2,85		600 ºC/6 h	2,75
	600 ºC/12 h	2,82		600 ºC/12 h	2,80

Tabela III Resultados da análise textural dos óxidos de MoO3.

Entrada	Reação hidrotérmica	Calcinação	Área superficial (m² /g)	Volume de poro (cm³ /g)	Tamanho de poro (Å)
1	180 ºC/1 h	-	30,7490	0,087640	93,379
2	180 ºC/6 h	-	9,5541	0,008404	37,405
3	180 ºC/1 h	300 ºC/6 h	39,4563	0,044782	51,349
4	180 ºC/6 h	300 ºC/6 h	40,5978	0,043987	50,058
5	180 ºC/1 h	300 ºC/12 h	38,8910	0,073724	67,575
6	180 ºC/6 h	300 ºC/12 h	44,0805	0,056238	52,871
7	180 ºC/1 h	450 ºC/6 h	39,2595	0,051134	50,1987
8	180 ºC/6 h	450 ºC/6 h	32,9211	0,036734	44,1183
9	180 ºC/1 h	450 ºC/12 h	53,1137	0,062951	46,6351
10	180 ºC/6 h	450 ºC/12 h	30,1362	0,033632	44,0973
11	180 ºC/1 h	600 ºC/6 h	53,9676	0,045421	36,1102
12	180 ºC/6 h	600 ºC/6 h	48,9480	0,040806	35,6100
13	180 ºC/1 h	600 ºC/12 h	54,1635	0,045752	36,1987
14	180 ºC/6 h	600 ºC/12 h	44,4488	0,037532	36,1482

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