Recovery of Gallic Acid with Colloidal Gas Aphrons generated from a cationic surfactant

Giorgia Spigno, Chiara Pastori, M. Dermiki, P. Jauregi

Risultato della ricerca: Contributo in rivistaArticolo in rivistapeer review

24 Citazioni (Scopus)

Abstract

In a previous study we have demonstrated that gallic acid (GA) in its anionic form can be recovered from aqueous solutions using colloidal gas aphrons (CGA) generated from the cationic surfactant cetyltrimethylammonium bromide (CTAB). The aim of the present work is to get a better understanding of the separation mechanism in order to determine the optimum operating conditions to maximise the recovery of GA whilst preserving its antioxidant properties. Zeta-potential measurements were carried out to characterise the surface charge of GA, CTAB and their mixtures at three different pH conditions (both in buffers and in aqueous solutions). GA interacted strongly with CTAB at pH higher than its pKa 3.14 where it is ionised and negatively charged. However, at pH higher than 7 GA becomes oxidised and loses its antioxidant power. GA recovery was mainly affected by pH, ionic strength, surfactant/GA molar ratio, mixing conditions and contact time. Scale-up of the separation using a flotation column resulted in both higher recovery and reproducibility. Preliminary experiments with grape marc extracts confirmed the potential application of this separation for the recovery of polyphenols from complex feedstocks.
Lingua originaleEnglish
pagine (da-a)56-62
Numero di pagine7
RivistaSeparation and Purification Technology
Volume2010
Stato di pubblicazionePubblicato - 2010

Keywords

  • antioxidants
  • cationic surfactant
  • colloidal gas aphrons
  • gallic acid
  • z-potential

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