Kinetic investigation of the ultrasound assisted extraction of polyphenols from spruce bark  Adina Iulia TALMACIU1, Liliana LAZAR2, Irina VOLF3, Valentin I. POPA1 “Gheorghe Asachi” Technical University of Iasi, Faculty of Chemical Engineering and Environmental Protection, 1Department of Natural and Synthetic Polymers; 2Department of Chemical Engineering; 3Department of Environmental Engineering and Management, 73 Dimitrie Mangeron Street, Iasi 700050, Romania

Objectives Factors influencing UAE Kinetic mechanism involved Kinetic models applied for UAE

Ultrasound assisted extraction (UAE) Why UAE? it’s a “green’’ technique it’s rapid (10 - 60 min extraction time) consumes low amounts of solvent, biomass and energy it’s easy to use offer high extraction yields is a low-cost technique

Materials and methods Biomass: Spruce bark resulted as waste from wood processing industry Operation conditions: Extraction using 70% ethanol as solvent Solid - solvent ratio 1:10 (g biomass/ mL solvent) Temperatures: 45 0C, 50 0C and 60 0C (318, 323, 333 K) Variable extraction time: 5 to 75 min Experimental equipment: ultrasound bath SONOREX RK 100H, 35 kHz frequency, 320 W power, automatic control of time and temperature

HPLC analysis for qualitative t polyphenols identification Experimental procedure Ultrasound bath Temperature = 45 0C, 50 0C, 60 0C Time = 5 – 75 min Extraction vessel 5 g spruce bark Ethnol 70 % (50 mL) Filtration 4 min, 4000 rpm Solid phase FTIR Spectrophotometric analysis for total polyphenolic content determination using Folin-Ciocalteu method HPLC analysis for qualitative t polyphenols identification Liquid phase

Table1: Polyphenolic content quantified by HPLC analysis Extract characterization Figure 3: Chromatographic profile of spruce bark extract obtained by UAE 500C, 30 min Table1: Polyphenolic content quantified by HPLC analysis Polyphenols Ret. time min Area mAU min Amount mg/L Height mAU Rel. area % Gallic acid 2.99 0.06 5.45 0.65 5.58 Catechin 9.35 2.16 112.08 5.76 3.33 Vanilic acid 13.66 0.53 15.20 2.45 0.82 Siringic acid 15.77 0.75 12.91 4.43 1.16 p-cumaric acid 19.93 13.29 99.47 39.54 20.42 Ferulic acid 23.59 0.57 9.70 3.54 0.88 Sinapic acid 23.77 0.33 13.36 2.50 0.52 Total 17.71 268.20 58.90 32.71

Experimental data - parameters study Figure 4: Effect of time on polyphenols extraction Figure 5: Effect of temperature on polyphenols extraction

second-order kinetic model Kinetics investigation - second-order kinetic model Figure 6: Mathematical checking of second-order kinetic model Table 2: Kinetic parameters of second-order kinetic model T, K B = 1/Ce A = 1/h Ce =1/B, mg/g h = 1/A k = h/(Ce)2 g/mg·min R2 318 0.0268 0.1402 37.31343 7.133 0.0051 0.9867 323 0.0248 0.0841 40.32258 11.891 0.0073 0.9926 333 0.0232 0.0574 43.10345 17.422 0.0094 0.9972 Goula (2013). Ultrasound-assisted extraction of pomegranate seed oil – Kinetic modeling. Journal of Food Engineering, 117, 492-498. Pan et al., (2012). Continuous and pulsed ultrasound-assisted extraction of antioxidants from pomegranate peel. Ultrasonics Sonochemistry, 19, 365-372.

second order kinetic model Kinetics investigation - second order kinetic model Figure 7: Relationship between temperature and second-order extraction rate constant (lnk) Figure 8: Relationship between initial extraction rate (lnh) and temperature Figure 9: Relationship between equilibrium concentration (Ce) and temperature

second-order kinetic model Kinetics investigation - second-order kinetic model Validity of model prediction Figure 10: Comparison between experimental and modeling concentrations for UAE of polyphenols from spruce bark

Conclusions Influence of temperature on the extraction yields concluded that the ultrasonic assisted extraction process of polyphenols from spruce bark is endothermic and based on a second-order kinetic model [1]; The extraction mechanism proceeds in two steps: a fast dissolution at the beginning followed by a slow diffusion[1]; Using the second-order model the second-order extraction rate constant, the equilibrium concentration and the initial extraction rate can be predicted, their dependence of temperature can be used to determinate the activation energy of the extraction[1,2]; Predicted values obtained from the second-order model are in a very good accordance with experimental results. [1] Rakotondramasy-Rabesiaka et al.,(2007). Solid–liquid extraction of protopine from Fumaria officinalis L.- Analysis determination, kinetic reaction and model building. Separation and Purification Technology, 54, 253-261. [2] Su, C-H., et al., (2014). Solid-liquid extraction of phycocyanin from Spirulina platensis: Kinetic modeling of influential factors. Separation and Purification Technology, 123, 64-68.

Thank you very much for your kind attention! PhD. eng. Adina Iulia TALMACIU E-mail: a.talmaciu@tuiasi.ro talmaciu.adina@gmail.com