Decolourisation of dye solutions by oxidation with H2O2 in the presence of modified activated carbons

• Type: Article in International Scientific Journal
• Date: 2009

Authors

V. P. Santos (Author) FEUP; M. F. R. Pereira (Author) FEUP; P. C. C. Faria (Author) FEUP; J. J. M. Órfão (Author) FEUP

Journal

Title: Journal of Hazardous Materials

Vol. 162

Pages: 736-742

ISSN: 0304-3894

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 127 Citations

ISI Web of Science

Scopus - 148 Citations

COMPENDEX

Scientific classification

FOS: Engineering and technology > Chemical engineering

Other information

Authenticus ID: P-003-MGT

DOI: 10.1016/j.jhazmat.2008.05.090

Abstract (EN): The decolourisation of dye solutions by oxidation with H2O2, using activated carbon as catalyst, is studied. For this purpose, three different samples, mainly differing in the respective surface chemistries, were prepared and characterized. Moreover, this work involved three pH levels, corresponding to acid, neutral and alkaline solutions, and six dyes belonging to several classes. The catalytic decolourisation tests were performed in a laboratorial batch reactor. Adsorption on activated carbon and non-catalytic peroxidation kinetic experiments were also carried out in the same reactor, in order to compare the efficiencies of the three processes. The non-catalytic reaction is usually inefficient and, typically, adsorption presents a low level of decolourisation. In these cases, the combination of activated carbon with hydrogen peroxide may significantly enhance the process, since the activated carbon catalyses the decomposition of H2O2 into hydroxyl radicals, which are very reactive. Based on the experiments with the different activated carbon samples, which have similar physical properties, it is proved that the surface chemistry of the catalyst plays a key role, being the basic sample the most active. This is discussed considering the involvement of the free electrons on the graphene basal planes of activated carbon as active centres for the catalytic reaction. Additionally, it is shown that the decolourisation is enhanced at high pH values, and a possible explanation for this observation, based on the proposed mechanism, is given.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 7