Chemical Engineering Journal, Vol.280, 748-754, 2015
Recovery of hydroxycinnamic acids from renewable resources by adsorption on zeolites
The aim of the study was to examine the adsorption capacity of hydroxycinnamic compounds (ferulic acid, p-coumaric acid, cinnamic acid) on zeolite adsorbents (FAU- and *BEA-type structures) versus Amberlite resin XAD16. The pH and contact time effects on adsorption were evaluated. The adsorption capacity was dependent on pH and higher at pH less than pKa(1). The kinetic adsorption is faster onto FAU and *BEA zeolites than onto XAD16 resin. Maximum adsorption capacities were calculated for the target compounds for pH = 3.5 by using the Langmuir isotherm model. They reached higher values for zeolites than for XAD16 and are respectively of 139, 122 and 109 mg g(-1) for ferulic, p-coumaric and cinnamic acids. Values around 30 mg g(-1) were observed for XAD16. Desorption ratios were close to 100% for *BEA zeolite and XAD16 resin in the presence of ethanol 96%. The use of regenerated zeolites led to a loss of adsorption capacities of 10% for *BEA zeolite. The latter is a particularly interesting adsorbent to isolate the hydroxycinnamic compounds from vegetal extracts. (C) 2015 Elsevier B.V. All rights reserved.