1. 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 , Romania

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

3. Ultrasound assisted extraction (UAE)
Why UAE?
it’s a “green’’ technique
it’s rapid ( 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

4. 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

5. 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

6. 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

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

8. 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
7.133
0.0051
0.9867
323
0.0248
0.0841
11.891
0.0073
0.9926
333
0.0232
0.0574
17.422
0.0094
0.9972
Goula (2013). Ultrasound-assisted extraction of pomegranate seed oil – Kinetic modeling. Journal of Food Engineering, 117,
Pan et al., (2012). Continuous and pulsed ultrasound-assisted extraction of antioxidants from pomegranate peel. Ultrasonics Sonochemistry, 19,

9. 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

10. 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

11. 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,
[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,

12. Thank you very much for your kind attention!
PhD. eng. Adina Iulia TALMACIU