Preparation of Molecularly Imprinted Adsorbents with Improved Retention Capability of Polyphenols and Their Application in Continuous Separation Processes
This research explores the use of molecularly imprinted polymers (MIPs) in continuous adsorption processes to target polyphenols
present in plant extracts. Different kinds of MIPs were prepared and tested in individual and competitive adsorption/
desorption assays. High polyphenol retention was shown to be possible, even when solvents of low water content are used. A
lower impact of hydrophobic interactions is observed with MIPs, namely in comparison with commercial synthetic resins,
and so, despite the absence of a perfect selectivity, molecular imprinting was congenial in the functionalization and improved
binding site accessibility. Moreover, the potential usefulness of the prepared MIPs to improve downstream processing of
polyphenols is also demonstrated through their application in chromatographic separation processes. The direct use of plant
extracts of high alcoholic content, avoiding the need for solvent change and water addition, the suppression of energetic costs
associated to water evaporation and the possibility to work in a wide range of polyphenols solubility are possible advantages
of the developed MIP adsorbents in such kinds of biorefining processes. The development of simulation tools to aid the
design and optimization of the involved continuous adsorption/desorption is also here addressed. In this work, MIPs were
tested with cork and chestnut shell extracts, a supercritical CO2
olive leaf extract and red wine. Results here obtained show
the successful isolation of ellagic acid with cork and chestnut shell extracts, oleuropein with the olive leaf extract and the
clear simplification of the red wine extract, enabling the identification/quantification of resveratrol, quercetin, kaempferol
and other polyphenols.
This work is a result of project “AIProcMat@
N2020—Advanced Industrial Processes and Materials for a Sustainable
Northern Region of Portugal 2020”, with the reference NORTE-
01-0145-FEDER-000006, supported by Norte Portugal Regional
Operational Programa (NORTE 2020), under the Portugal 2020 Partnership
Agreement, through the European Regional Development Fund
(ERDF) and of Project POCI-01-0145-FEDER-006984—Associate
Laboratory LSRE-LCM funded by ERDF through COMPETE2020—
Programa Operacional Competitividade e Internacionalização
(POCI)—and by national funds through FCT—Fundação para a Ciência
e a Tecnologia. We also acknowledge the contribution of the master
student Cátia Afonso.
