Journal of Food, Agriculture and Environment

Removal of some disazo compounds from water by photocatalysis

Author(s):

Jeanne Atchana ¹, Georgeta M. Simu ^2*, Simona G. Hora ³, Maria E. Grad ³, Jean B. Tchatchueng ⁴, Benoît L. Benguellah ¹, Richard Kamga ⁴

Recieved Date: 2010-09-08, Accepted Date: 2011-01-11

Abstract:

An environmentally friendly photochemical treatment, e.g. the photocatalysis process, was applied to the depollution of a synthetic dismissal composed by three disazo compounds derived from 4,4’-diaminobenzanilide (dye I and III) and 4,4’-diaminostilben -2,2’-disulfonic acid (dye II). The photocatalytic degradation of these compounds with different chemical structures has been investigated using TiO₂-MoO₃ photocatalyst in aqueous solution, under UV irradiation. The process was monitored by UV-Vis spectroscopy. The decrease of the absorption peaks of the dyes at their maximum absorption wavelength was studied, and in all cases, a rapid decolourisation of the aqueous solutions of the disazo dyes I – III occurred. Further, chemical oxygen demand measurements (COD) were carried out in order to evaluate the mineralization efficiency of the azo compounds I-III, during the UV/TiO₂-MoO₃ photocatalytic process. The obtained results indicated that the studied compounds are quickly degraded under the current controlled photolysis conditions, leading to an almost complete mineralization. In the case of the disazo dye I, a sample containing initially a COD of 1056 mg O₂ l^-1 was successfully mineralized with the COD abatement ratio of 94.2% after 25 min. Similar results were obtained in the case of dyes II and III. These findings show that the studied photocatalytic process may be classified as an advanced oxidation process, which is able to quickly degrade aqueous solutions containing synthetic azo compounds. As hydroxyl radicals are non-selective oxidation agents, the process can be extended to the treatment of different wastewaters contaminated by other persistent organic pollutants.

Keywords:

Environmental pollution, water wastage, photocatalysis, advanced oxidation process, disazo dyes, 4,4’-diaminobenzanilide, 4,4’-diaminostilbene-2,2’-disulfonic acid, TiO₂-MoO₃, chemical oxygen demand, mineralization

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Journal: Journal of Food, Agriculture and Environment
Year: 2011
Volume: 9
Issue: 1
Category: Environment
Pages: 457-460

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