Kinetics of the hydrothermal treatment of tannin for producing carbonaceous microspheres.
Aqueous solutions of condensed tannins were submitted to hydrothermal carbonization (HTC) in a stainless steel autoclave, and the kinetics of hydrothermal carbon formation was investigated by changing several parameters: amount of tannin (0.5; 1.0; 1.5; 2.0 g in 16 mL of water), HTC temperature (130, 160, 180 and 200°C) and reaction times (from 1 to 720 h). The morphology and the structure of the tannin-based hydrothermal carbons were studied by TEM, krypton adsorption at -196°C and helium pycnometry. These materials presented agglomerated spherical particles, having surface areas ranging from 0.6 to 10.0 m(2) g(-1). The chemical composition of the hydrothermal carbons was found to be constant and independent of reaction time. HTC kinetics of tannin were determined and shown to correspond to first-order reaction. Temperature-dependent measurements led to an activation energy of 91 kJ mol(-1) for hydrothermal conversion of tannin into carbonaceous microspheres separable by centrifugation.
Université de Lorraine, ENSTIB, 27 rue Philippe Séguin, CS 60036, 88026 Epinal Cedex, France; Institut Jean Lamour, Département 4: Nanomatériaux Electronique Et Vivant, UMR 7198, ENSTIB, 27 rue Philippe Séguin, CS 60036, 88026 Epinal Cedex, France.
F L
FL
Braghiroli
V
V
Fierro
M T
MT
Izquierdo
J
J
Parmentier
A
A
Pizzi
A
A
Celzard
D001709:Biotechnology / Q000379:methods*; D002244:Carbon / Q000737:chemistry*; D007700:Kinetics; D008863:Microspheres; D010316:Particle Size; D013634:Tannins / Q000737:chemistry*; D013696:Temperature; D014867:Water / Q000494:pharmacology*
D013634:Tannins; D014867:Water; D002244:Carbon
Carbonaceous microspheres; Hydrothermal carbonization; Kinetics; Tannin