Selective recovery of polyphenols from MDF process waters by adsorption on a macroporous, cross-linked pyrrolidone-based resin

Abstract

Abstract A scalable, fixed-bed adsorption system for the removal and selective recovery of polyphenols (lignans and stilbenes) from medium-density fiberboard (MDF) process waters was developed. Before adsorption, fibers and non-colloidal substances were removed from process water by centrifugation, while colloidal fatty and resin acids were removed by filtration through a 30-kDa cut-off membrane. Polyphenols were then isothermally adsorbed on a medium-pressure liquid chromatography (MPLC) column packed with Divergan® RS, a regenerable macroporous, cross-linked pyrrolidone-based [polyvinylpolypyrrolidone (PVPP)] resin. Loading at acidic pH and subsequent gradient elution of polyphenols with methanol were monitored at 280 nm, and elution conditions for selective polyphenol recovery were optimized based on gas chromatography/mass spectrometry (GC/MS) analyses of the obtained fractions. Lignans were eluted in successive fractions containing the individual lignans in different proportions, followed by pinosylvin in a separate fraction. The capacity of the PVPP for hydroxymatairesinol (HMR) as a model lignan was determined to be 37.4 mg g−1 at 1% breakthrough. Highly polar substances such as sugars and sugar alcohols, however, were not retained on the column and remained in the flow-through. The results revealed the benefits of PVPP for the recovery of potentially valuable polyphenols from MDF process waters while reducing carbon load and toxicity for subsequent biological treatment.