SELECTIVE ADSORPTION ON FIBROUS ACTIVATED CARBON OF ORGANICS FROM AQUEOUS-SOLUTION - CORRELATION BETWEEN ADSORPTION AND MOLECULAR-STRUCTURE

In industrial processes, granular activated carbon (GAG) is generally used to remove pollutants from wastewater. Recently, a new adsorbant h as been explored, fibrcus activated carbon (FAG). Experiments were car ried out with two FACs having different specific surface areas (1500 a nd 1300 m(2).g(-1)) and pore-size distributions to study adsorption of various organic compounds from aqueous solution. Results were compare d with adsorption onto one GAC with a specific surface area of about 1 000 m(2).g(-1). Classic models were applied and kinetic constants were computed. In most cases, FAC with the higher specific surface area (n amed CS 1501) showed better adsorption capacities and kinetics than th e two ether FACs. For example, adsorption velocity of benzaldehyde was 7.2 xi 10(-5) l.mg(-1).min(-1) with CS 1501 and about 3 xi 10(-5) l.m g(-1).min(-1) with other FACs. Furthermore, adsorption onto CS 1501 of a great number of organic compounds (aliphatic and aromatic) depended on solute molecular characteristics. For instance, solute molecular s ize seemed to play an important role: adsorption capacity of high mole cular weight compounds (humic substances) was about 3 mg.g(-1), a valu e much lower than those of low molecular weight compounds, which were respectively 200 mg.g(-1) and 400 mg.g(-1) for phenol and benzoic acid . From experimental results, a correlation of QSAR (Quantitative Struc ture-Activity Relationship) type has been set up. This relationship pr edicts the adsorbability of organics compounds onto fibrous activated carbon from the molecular properties of these compounds. (C) 1997 IAWQ . Published by Elsevier Science Ltd.