On the adsorption mechanisms of diethylamine by medically-certified activated carbons: Investigation of critical parameters controlling sorption properties
Résumé
This study investigates the adsorption mechanisms and reaction pathways involved in the adsorption of
diethylamine (DEA) by medically-certified activated carbons (ACs). DEA is used as a model of amines
secreted during healing process of chronic wounds. DEA adsorption kinetics/isotherms were performed
in liquid phase. Based on a preliminary assumption of a sorption favoured by surface chemical functions,
it was found that the sorption kinetics followed accurately a pseudo-second order model. In addition, our
analysis revealed that surface diffusion strongly influenced DEA sorption. If Langmuir and Redlich–
Peterson models provided the most accurate fit of the adsorption isotherms, the Freundlich isotherm
gave a fair representation of experimental data as well. L-type isotherms supported the occurrence of
strong surface interactions. Also, a negative correlation was drawn between the micropore volume
percentage and adsorption capacity at equilibrium. Further, acid/base reactions were believed to occur,
along with the establishment of numerous H-bonds between the sorbent and DEA. This study is ended by
a discussion of the effect of AC entrapment within a polymeric matrix on the adsorption properties. If
DEA removal was still observed, a serious decrease of sorption properties was measured. We concluded
that AC must be treated during the activation process in order to possess a high BET surface, an important
mesopore/macropore content and a high content of acidic surface functions, in order to balance the
decreasing of adsorption properties owed to its entrapment.