TY - JOUR
T1 - Recovery of gallic acid with colloidal gas aphrons generated from a cationic surfactant
AU - Spigno, G.
AU - Dermiki, M.
AU - Pastori, C.
AU - Casanova, F.
AU - Jauregi, P.
PY - 2010/1/29
Y1 - 2010/1/29
N2 - 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 while 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.
AB - 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 while 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.
KW - Antioxidants
KW - Cationic surfactant
KW - Colloidal gas aphrons
KW - Gallic acid
KW - z-potential
UR - http://www.scopus.com/inward/record.url?scp=76449103746&partnerID=8YFLogxK
U2 - 10.1016/j.seppur.2009.11.002
DO - 10.1016/j.seppur.2009.11.002
M3 - Article
AN - SCOPUS:76449103746
SN - 1383-5866
VL - 71
SP - 56
EP - 62
JO - Separation and Purification Technology
JF - Separation and Purification Technology
IS - 1
ER -