Static and dynamic adsorption studies of PolyChloroBiphenyls (PCBs) over activated carbons
Résumé
Since PolyChloroBiphenyls (PCBs) have been extensively used in the
past century, they are frequently detected in surface water and ground
water. Due to their poor solubility, extremely low concentrations are
observed in water. However, PCBs were demonstrated more recently to be
highly toxic and need to be eliminated. The adsorption rapidly appeared
as a key technology for their efficient and economical removal from
water. In this study, activated carbons were shown to be highly
efficient in the adsorption of 2-PCB under static conditions, i.e. at
long contact time (several hours) when the adsorption-desorption
equilibrium was reached. Under such conditions, the main key parameter
was shown to be the activated carbon texture (specific surface area,
porosity). Moreover, the main driving force was identified to be the
combination between the very limited solubility of 2-PCB in pure water
and the hydrophobic nature of the activated carbon. In turn, under
dynamic conditions, i.e. at short contact time (less than 5s), the
overall adsorption process was shown to be quite inefficient and
unambiguously controlled by internal surface diffusion limitations. In
this later case, the operating parameters, especially the activated
carbon bed morphology, played a major role. Copyright 2015 Elsevier Ltd. All rights reserved.