Recovery of phenolic compounds from Eucalyptus wood wastes using ethanol-salt-based aqueous two-phase systems

Lucía Xavier,M Sonia Freire,Isabel Vidal-Tato

doi:10.4067/s0718-221x2017005000001

Lucía Xavier, M Sonia Freire + Show 1 more

Open Access

https://doi.org/10.4067/s0718-221x2017005000001

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Abstract

In this work the partition behavior of phenols using ethanol-salt-based aqueous two phase systems (ATPS) was evaluated. The aim was the recovery of phenolic compounds with antioxidant capacity from eucalyptus wood industrial wastes. Experiments were planned to study the influence of several parameters on phenols partition, including type of inorganic salt (ammonium sulphate, a mixture of monopotassium phosphate and potassium diphosphate and potassium diphosphate), tie-lie lenght (TLL), volume ratio (Vr), settlement time and temperature. Phenols could be recovered preferently from the top or bottom phases depending on the salt used. It was demostrated that tie-lie lenght, volume ratio and temperature had influence on phenols partition. The highest total phenols yield 5,36 mg gallic acid equivalent (100 mg oven dried wood)-1 and FRAP antioxidant activity, 20 mmol AAE (100 g oven dried wood)-1, was obtained using ATPS formed by 40.6% (w/w) ethanol and 12% (w/w) of ammonium sulphate at 65oC. Analysis of the extract by RP-HPLC-ESI-TOF confirmed the presence of the phenolic compounds with potential antioxidant activity, namely, ellagic acid, myricetin 3-O-rhamnoside and quercetin 3-glucoside.

Highlights

Aqueous two-phase system (ATPS) extraction is a liquid-liquid extraction technique that has been used for the extraction and partial purification of a wide variety of biomolecules (Rosa et al 2010, Espitia-Saloma et al 2014, Reis et al 2014, Wu et al 2014)
In order to study the time at which the partition of phenols stabilizes, a system was selected for each type of ethanol-salt ATPS (Systems 5, 7 and 11, Table 1) and extraction was performed at 25oC, using three different settlement times (1, 6 and 15 h) for phase separation
Comparing the results obtained for the three ATPS studied the highest TPY was obtained for the top phase of the ethanol/(NH4)2SO4 system (2,81 mg gallic acid equivalents (GAE) (100 mg of o.d. wood)-1)

Summary

Introduction

Aqueous two-phase system (ATPS) extraction is a liquid-liquid extraction technique that has been used for the extraction and partial purification of a wide variety of biomolecules (Rosa et al 2010, Espitia-Saloma et al 2014, Reis et al 2014, Wu et al 2014). ATPS form when an aqueous solution exceeds a critical concentration of two water soluble, but mutually incompatible, components (Albertsson 1986) This technique is recognized as an alternative for the fractionation of biomolecules due to economic advantages and technological simplicity (Rosa et al 2010, Espitia-Saloma et al 2014). ATPS could be considered as an integrated process, in which the insoluble components can be removed while at the same time the target product is purified (Rosa et al 2010) This leads to lower energy costs as the steps of operation are reduced, getting more concentrated and purified biomolecules (Rosa et al 2010). In recent years alternative ATPS including alcohol-salt, ionic liquid-salt and micel-

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