Adsorption of alkylphenols onto microporous carbons prepared from coconut shell

Abstract

In order to obtain fundamental data on removal of the alkylphenol (AP) group of endocrine-disrupting chemicals, seven microporous carbons with specific surface area of 513–1828 m 2/g were prepared from coconut shell, and the adsorption isotherms of APs with alkyl chains consisting of 5–9 carbon atoms were measured. The following results were obtained: the amount of 4-nonylphenol adsorbed at equilibrium concentrations above 20 μg/l increased with activation time; the amount adsorbed at 1 μg/l increased with activation time from 0.5 to 2.5 h, but decreased from 2.5 to 4.5 h. This decrease under prolonged activation is attributable to the effect of decreased dispersion force through pore enlargement being greater than the effect of increased specific surface area. The amount of APs adsorbed at above 10 μg/l was higher for APs with a linear alkyl chain of 5–7 carbon atoms than for those with branched alkyl chains of 8–9 carbon atoms due to a molecular sieving effect in the latter.