## 3 Experimental  
### Materials  
_Winery wastes_. Winery wastes from _Cooperativa Vitivinicola do Ribeiro_ (Ribadavia, Ourense, Spain), years 2007-2008, were collected and processed to separate the solid and liquid fractions. The obtained liquid phase was centrifuged to remove suspended solids, diluted with tap water and stored at 4 \({}^{\circ}\)C until use. The total phenolic and sugar content in the diluted liquid phase were 1.8 g (expressed as gallic acid equivalents)/L and 6.0 g/L, respectively. _Resins_. The food grade resins used were an acrylic polymer, Amberlite XAD7 HP, two resins with a formaldehyde-phenol polycondensed matrix, Amberlite XAD761 and Amberlite XAD1180, and three PS-DVB resins, Amberlite XAD2, Amberlite XAD4 and Amberlite XAD16, supplied by Sigma Chemical Corporation. PS-DVB copolymers with different hydrophobicity, Sepabeads SP700, Sepabeads SP207, Sepabeads SP825, Sepabeads SP850 and Diaion HP20, a resin with a polymethacrylate estructure, Diaion HP2 MG and a chemically modified PS-DVB polymer, Sepabeads SP70, were kindly supplied by Resindion S.R.L. (Mitsubishi Chemical Corporation). The physicochemical characteristics of these resins are summarized in Table 8.  
The resins were activated by contact with sufficient methanol to cover the resin bed by 2.5-5 cm (Sigma-Aldrich, Madrid, Spain). Resins and methanol were blended gently by shaking one minute and then the suspension was stirred at 175 rpm and 25 \({}^{\circ}\)C during 15 min. Before use resins were rinsed with deionized water at a liquid to solid ratio of 5 (g/g). The moisture content of the resins was \begin{table}
\begin{tabular}{l l c c c c c} \hline \hline \multirow{2}{*}{**Resin Name**} & \multirow{2}{*}{**Structure**} & **Surface** & **Pore** & **Porosity** & **Particle** & **Density** \\  & & **Area (m\({}^{2}\)/g)** & **Radius (Å)** & **(mL/g)** & **Size (mm)** & **(g/mL)** \\ \hline
**Amberlite** & & & & & & \\ \hline XAD2 & PS-DVB & 330 & 90 & 0.65 & 0.25–0.84 & 1.02 \\ XAD4 & PS-DVB & 725 & 40 & 0.98 & 0.25–0.84 & 1.02 \\ XAD7 HP & Acrylic ester & 450 & 90 & 1.14 & 0.25–0.84 & 1.05 \\ XAD16 & PS-DVB & 800 & 100 & 1.82 & 0.25–0.84 & 1.02 \\ XAD761 & Phenol-formaldehyde & 300 & 600 & 0.43 & 0.56–0.76 & 1.11 \\ XAD1180 & Phenol-formaldehyde & 600 & 300 & 1.68 & 0.35–0.60 & 1.01 \\ \hline
**Diaion** & & & & & & \\ \hline HP20 & PS-DVB & 600 & 260 & 1.3 & 0.25–0.60 & 1.01 \\ HP2 MG & Polymethacrylate & 470 & 170 & 1.2 & 0.25–0.60 & 1.09 \\ \hline
**Sepabeads** & & & & & & \\ \hline SP70 & Chemically modified & 800 & 70 & 1.6 & 0.25–0.85 & 1.01 \\  & PS-DVB (Br-PS-DVB) & & & & & \\ SP207 & PS-DVB & 630 & 120 & 1.1 & 0.25–0.60 & 1.18 \\ SP700 & PS-DVB & 1200 & 90 & 2.3 & 0.25–0.70 & 1.01 \\ SP825 & PS-DVB & 1000 & 57 & 1.4 & 0.30–0.50 & 1.01 \\ SP850 & PS-DVB & 1000 & 38 & 1.2 & 0.30–0.80 & 1.01 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Physicochemical characteristics of the commercial resins used for the recovery of phenolic compounds from winery wastes. determined by drying the beads in an oven at 100 \({}^{\circ}\)C up to constant weight, and adsorption experiments were carried out utilizing known amounts of resins. _Absorption._ The centrifuged winery liquid wastes were contacted in batch mode with weighed quantities of hydrated resins in sealed Erlenmeyer flasks at 25 \({}^{\circ}\)C in an orbital shaker at 175 rpm. The concentration of phenolics adsorbed at time \(t\) onto a mass unit of resin (_q_t, mg/g) was measured as gallic acid equivalents and calculated by the equation:  
\[q_{t}=\frac{(C_{0}-C_{t})V}{W} \tag{1}\]  
where \(C_{0}\) and \(C_{t}\) are the concentrations of phenol in the aqueous solution (mg/L) at the initial stage and at \(t\) time, respectively, \(V\) is the volume of the solution added into the flask (L), and \(W\) is the weight of the wet resin (g). Experiments were performed in triplicate.