caa a22 4500 445388250 CHVBK 20180317143038.0 cr unu---uuuuu 170323e20111001xx s 000 0 eng 10.1007/s11144-011-0350-z doi (NATIONALLICENCE)springer-10.1007/s11144-011-0350-z A shrinking core model for slow combustion of solid 5- O -caffeoylquinic acid [Elektronische Daten] [Everton Zanoelo, Cristina Benincá] The oxidation of 5-O-caffeoylquinic acid (5-CQA) was investigated in the temperature range from 161 to 188°C. The kinetic experiments were carried out in small batch reactors made of glass, where a very thin (1.1μm) fixed bed of powder 5-CQA was in contact with air at approximately 91.4kPa. Aqueous 5-CQA solutions were prepared with the solid found in the reactors at different reaction times and used to measure the decrease of 5-CQA concentrations with a spectrophotometer operated at 323nm. A shrinking core model was applied to describe the non-catalytic heterogeneous reaction between 5-CQA and oxygen. It basically assumes mass transfer of O2 from bulk air to the outer surface of nonporous particles of solid 5-CQA, where an irreversible reaction with no formation of solid products takes place. The proposed model correctly reproduced the obtained kinetic results in all the investigated operating conditions when an exponential reduction of external area of solid with reaction time was taken into account. Arrhenius-type expressions successfully described the dependence of the calculated global reaction and shrinking rate constants on temperature. An activation energy close to 77046Jmol−1 was found for the slow combustion reaction of 5-CQA. Akadémiai Kiadó, Budapest, Hungary, 2011 5-CQA nationallicence CGA nationallicence Chlorogenic acids nationallicence Shrinking core model nationallicence Slow combustion nationallicence a : External surface area of solid per initial volume of bed (m2m−3) nationallicence a i : Initial external surface area of solid per initial volume of bed (m2m−3) nationallicence A : Absorbance of aqueous solution of 5-CQA (mAu) nationallicence k c : External coefficient of mass transfer (ms−1) nationallicence k r : Rate constant of combustion of 5-CQA (m4mol−1s−1) nationallicence k 1 : Tuned parameter of the shrinking core model (s−1) nationallicence k 2 : Tuned parameter of the shrinking core model (dimensionless) nationallicence k 3 : Tuned parameter of the shrinking core model (dimensionless) nationallicence t : Time (s) nationallicence T : Temperature (°C) nationallicence X : Dimensionless concentration of 5-CQA nationallicence [5-CQA] : Concentration of 5-O-caffeoylquinic acid (molm−3) nationallicence [5-CQA]i : Initial concentration of 5-O-caffeoylquinic acid (molm−3) nationallicence [O2] g : Bulk concentration of oxygen in the gas phase (molm−3) nationallicence [O2] s : Concentration of oxygen at the surface of powder solid 5-CQA (molm−3) nationallicence Zanoelo Everton Department of Chemical Engineering, Federal University of Paraná, Polytechnic Center (DTQ/ST/UFPR), Jardim das Américas, 81530-990, Curitiba, PR, Brazil aut Benincá Cristina Department of Chemical Engineering, Federal University of Paraná, Polytechnic Center (DTQ/ST/UFPR), Jardim das Américas, 81530-990, Curitiba, PR, Brazil aut Reaction Kinetics, Mechanisms and Catalysis Springer Netherlands 104/1(2011-10-01), 27-36 1878-5190 104:1<27 2011 104 11144 https://doi.org/10.1007/s11144-011-0350-z text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s11144-011-0350-z text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Zanoelo Everton Department of Chemical Engineering, Federal University of Paraná, Polytechnic Center (DTQ/ST/UFPR), Jardim das Américas, 81530-990, Curitiba, PR, Brazil aut NATIONALLICENCE 700 1- Benincá Cristina Department of Chemical Engineering, Federal University of Paraná, Polytechnic Center (DTQ/ST/UFPR), Jardim das Américas, 81530-990, Curitiba, PR, Brazil aut NATIONALLICENCE 773 0- Reaction Kinetics, Mechanisms and Catalysis Springer Netherlands 104/1(2011-10-01), 27-36 1878-5190 104:1<27 2011 104 11144 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer