Heterogeneous kinetics of the reduction of chromium (VI) by elemental iron

• Tipo: Artigo em Revista Científica Internacional
• Data: 2010

Autores

fiuza, a (Autor) FEUP; silva, a (Autor) Outra; carvalho, g (Autor) Outra; de la fuente, av (Autor) Outra; delerue-matos, c (Autor) Outra

Revista

Título: Journal of Hazardous Materials

Vol. 175

Páginas: 1042-1047

ISSN: 0304-3894

Editora: Elsevier

Indexação

ISI Web of Knowledge - 39 Citações

ISI Web of Science

Scopus - 21 Citações

COMPENDEX

Classificação Científica

FOS: Ciências da engenharia e tecnologias > Engenharia do ambiente

Outras Informações

ID Authenticus: P-003-89T

DOI: 10.1016/j.jhazmat.2009.10.116

Abstract (EN): Zero valent iron (ZVI) has been extensively used as a reactive medium for the reduction of Cr(VI) to Cr(III) in reactive permeable barriers. The kinetic rate depends strongly on the superficial oxidation of the iron particles used and the preliminary washing of ZVI increases the rate. The reaction has been primarily modelled using a pseudo-first-order kinetics which is inappropriate for a heterogeneous reaction. We assumed a shrinking particle type model where the kinetic rate is proportional to the available iron surface area, to the initial volume of solution and to the chromium concentration raised to a power a which is the order of the chemical reaction occurring at surface. We assumed alpha = 2/3 based on the likeness to the shrinking particle models with spherical symmetry. Kinetics studies were performed in order to evaluate the suitability of this approach. The influence of the following parameters was experimentally studied: initial available surface area, chromium concentration, temperature and pH. The assumed order for the reaction was confirmed. In addition, the rate constant was calculated from data obtained in different operating conditions. Digital pictures of iron balls were periodically taken and the image treatment allowed for establishing the time evolution of their size distribution.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 6