Artigo De Nitrato

Abstract

Adsorption at various interfaces has concerned scientists since the beginning of this

century. This phenomenon underlies a number of extremely important processes of utilitarian

significance. The technological, environmental and biological importance of adsorption

can never be in doubt. Its practical applications in industry and environmental protection

are of paramount importance. The adsorption of substrates is the first stage in many

catalytic processes. The methods for separation of mixtures on a laboratory and on an

industrial scale are increasingly based on utilising the change in concentration of components

at the interface. Moreover, such vital problems as purification of water, sewages, air

and soil are involved here too. On the other hand, many areas in which technological

innovation has covered adsorption phenomena have been expanded more through art and

craft than through science. A basic understanding of the scientific principles is far behind; in

part because the study of interfaces requires extremely careful experimentation if meaningful

and reproducible results are to be obtained. In recent years, however, considerable effort

has been increasingly directed toward closing the gap between theory and practice. Crucial

progress in theoretical description of the adsorption has been achieved, mainly through the

development of new theoretical approaches formulated on a molecular level, by means of

computer simulation methods and owing to new techniques which examine surface layers or

interfacial regions. Moreover, during the last 15 years new classes of solid adsorbents have

been developed, such as activated carbon fibres and carbon molecular sieves, fullerenes and

heterofullerenes, microporous glasses and nanoporous  both carbonaceous and inorganic

 materials. Nanostructured solids are very popular in science and technology and have

gained extreme interest due to their sorption, catalytic, magnetic, optical and thermal

properties. Although the development of adsorption up to the 1918s has been following

Part of this article has been presented as the Keynote Lecture during AI-SCP’99 Conference,

24
27 May 1999, Beijing, China.

Tel.: 48-81-537-5605; fax: 48-81-537-5685.

E-mail address: [e-mail] ŽA. D˛abrowski..

0001-868601$ - see front matter
2001 Elsevier Science B.V. All rights reserved.

PII: S 0 0 0 1 - 8 6 8 6 Ž 0 0 . 0 0 0 8 2 - 8

136 A. D˛abrowski Ad
ances in Colloid and Interface Science 93 (2001) 135
224

rather a zig
zag path, this arm of surface science is now generally considered to have

become a well-defined branch of physical science representing an intrinsically interdisciplinary

area between chemistry, physics, biology and engineering. This review presents in

brief the history of adsorption and highlights the progress in theoretical description of the

phenomenon under consideration. The paper deals with the above problems critically,

showing the development of adsorption, presenting some of the latest important results and

giving a source of up-to-date literature on it. Moreover, in this paper the most important

aspects are overviewed referring to today’s trends and visions in application of adsorption

science in industry, environmental protection and in environmental analysis. The relationship

between de
elopment of adsorption theory and adsorption practice is pointed out. Current

understanding and perspectives pertaining to applications of adsorption phenomena on

laboratory and on industrial scale as well as environmental protection are discussed and

illustrated by means of a few spectacular examples.
2001 Elsevier Science B.V. All rights

reserved.

Contents

1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137

2. Historical aspects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141

2.1. Pioneering experimental age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142

2.2. Pioneering theoretical age. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143

3. Catalysis and its relationship with adsorption . . . . . . . . . . . . . . . . . . . . . . . . . . 153

4. Current state of physical adsorption. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156

4.1. Adsorption on heterogeneous solids . . . . . . . . . . . . . . . . . . . . . . . . . . . 156

4.1.1. Adsorption of single gases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156

4.1.2. Adsorption of gas mixtures . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162

4.1.3. Adsorption of liquid mixtures . . . . . . . . . . . . . . . . . . . . . . . . . . . 163

4.1.4. Fractal approach to adsorption . . . . . . . . . . . . . . . . . . . . . . . . . . 165

4.1.5. Kinetics and dynamics of adsorption