Recovery of nickel octaethylporphyrin multilayers from bituminous extracts using low cost adsorbent

Abstract

The cyclicity of adsorption processes is crucial for the evaluation of the method as alternative to the extractives commonly used for the separation of petroporphyrins from oil. The adsorption and desorption processes of nickel octaethylporphyrin (Ni-OEP) on coconut shell activated carbon (CSAC) were evaluated under model and real experimental conditions. For the model system, kinetic, equilibrium and thermodynamic studies of adsorption were performed. The characterization of bituminous extract fractions was performed by APPI FT-ICR-MS. The presence of naturally occurring Ni-OEP in the extract was verified. The adsorption mechanisms involved the formation of acid-base and π-π interactions, with preferential adsorption of polar heteroatoms present in the bituminous extract, forming a potentially adsorbent monolayer. The adsorption of Ni-OEP from the extract was favored and about 50 % of the porphyrin present in the extract was recovered. The selective desorption supports the potential of employing sorption processes in the recovery of porphyrins from oil.