Sorption behavior of four tropical woods using a dynamic vapor sorption standard analysis system
Keywords:
Adsorption, desorption, equilibrium moisture content, sorption isotherm, sorption hysteresis, tropical woods.Abstract
Sorption behavior of four tropical woods coming from Cameroon is studied using a Dynamic Vapor Sorption-Intrinsic apparatus. Sorption isotherms at 20°C and 40°C of Triplochiton scleroxylon (obeche), Entandrophragma cylindricum (sapele), Sterculia rhinopetala (lotofa) and Terminalia superba (frake also called limba) are compared to those in the literature with methods using saturated salts for lotofa and frake with satisfactory results. Experimental values are fitted using two sorption isotherm models. Sorption hysteresis is greatest in sapele and least in frake. When temperature increases, differences in the hysteresis of sorption among the woods decreases. Hystereses of all studied woods ranged from 0,5 to 3%. Our studied woods have lower equilibrium moisture content probably caused by the higher values of extractives content. The water sorbed molecules on multilayer during both adsorption and desorption at 20°C and 40°C is greater in the case of frake and lower in the case of lotofa. The water sorbed molecules on multilayer of sapele is greater than those of obeche. The predominance of multilayer over monolayer of our woods is from 0,2 to 0,4 relative humidity in adsorption phase, and from 0,3 to 0,4 relative humidity in desorption phase.
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Alix, S.; Philippe, E.; Bessadok, A.; Lebrun, L.; Morvan, C.; Marais, S. 2009. Effect of chemical treatments on water sorption and mechanical properties of flax fibres. Bioresource Technology (100): 4742-4749.
Björk, H.; Rasmuson, A. 1995. Moisture equilibrium of wood and bark chips in superheated steam. Fuel 74 (12):1887-1890.
Bonoma, B.; Simo Tagne, M. 2005. A contribution to the study of the drying of ayous (Triplochiton scleroxylon) and of ebony (Diospyros ebenum). Phys Chem News (26):52-56.
Deliiski, N. 2011. Evaluation of wood sorption models and creation of precision diagrams for the equilibrium moisture content. Drvna Industrija 62(4):301-309.
De Palacios, P.; Estebán, L.G.; Fernández, F.G.; Garcia Iruelá, A.; Gonzáles Adrádos, J.R.; Conde, M. 2011. Comparative study of the 35°C sorption isotherms of cork stripped from the tree in 1968 and 2006. BioResources 6(2):2135-2144.
Dieste, A.; Krause, A.; Mai, C.; Militz, H. 2010. The calculation of EMC for the analysis of wood/water relations in Fagus sylvatica L. modified with 1,3-dimethylol-4,5-dihydroxyethyleneurea. Wood Sci Technol (44):597-606.
Engelund, E.T.; Klamer, M.; Venås, T.M. 2010. Acquisition of sorption isotherms for modified woods by the use of dynamic vapour sorption instrumentation: Principles and Practice. IRG/WP 10-40518, 41st Annual Meeting, Biarritz, France, 9-13 May 2010.
Esteban, L.G.; Casasus, A.G.; De Palacios, P.; Fernandez, F.G. 2004. Saturated salt method determination of hysteresis of Pinus sylvestris L. wood for 35 degrees C isotherms. Mater Constr (54):51-64.
Esteban, L.G.; De Palacios, P.; Fernandez, F.G. ; Guindeo, A. ; Navarro, N. 2008. Thermodynamic characterization of particleboard using sorption isotherms. Wood Research 53(2):45-56.
Esteban, L.G.; Fernandez, F.G. ; Guindeo, A.C. ; De Palacios, P.; Gril J. 2006. Comparison of the hygroscopic behaviour of 205-year-old and recently cut juvenile wood from Pinus sylvestris L. Annals of Forest Science 63(3):309-317.
Fernández, F.G.; De Palacios, P.; Esteban, L.G.; Iruela, A.G.; Gonzáles Adrádos, J.R.; López
Álvarez, J.V. 2012. Sorption and thermodynamic properties of cork from the 35°C and 50°C isotherms.
Bois et forêts des Tropiques 311(1) :63-74.
Fernández, F.G.; Esteban, L.G.; De Palacios, P.; Cristina S.; Iruela A.G.; De la Fuente, J. 2014. Sorption and thermodynamic properties of Terminalia superb Engl. & Diels and Triplochiton scleroxylon K. Schum. Through the 15, 35 and 50°C sorption isotherms. Eur. J. Wood Prod (72):99-106.
Hailwood, A.J.; Horrobin, S. 1946. Absorption of water by polymers: analysis in terms of a simple model. Trans. Faraday Soc (42):84-92.
Hill, C.A.S.; Norton, A.; Newman, G. 2009. The water vapour sorption behaviour of natural fibers. Journal of Applied Polymer Science 11:1524-1537.
Jalaludin, Z.; Hill, C.; Kermani, A. 2009. Moisture adsorption isotherms of wood using dynamic vapor sorption. CTE, SEBE, Napier University, Edinburgh, UK.
Jannot, Y. 2008. Isothermes de sorption: modèles et détermination. 16 p.
Jannot, Y.; Kanmogne, A.; Talla, A.; Monkam, L. 2006. Experimental determination and modelling of water desorption isotherms of tropical woods: afzelia, ebony, iroko, moabi and obeche. Holz Roh- Werkst (64):121-124.
Ouafia, N.; Moghrani, H.; Benaouada, N.; Yassaa, N.; Maachi, R.; Younsi, R. 2015. Moisture sorption isotherms and heat of sorption of Algerian bay leaves (Laurus nobilis). Maderas. Ciencia y tecnología 17(4):759-772.
Popper, R.; Niems, P.; Croptier, S. 2009. Adsorption and desorption measurements on selected exotic wood species. Analysis with the Hailwood-Horrobin model to describe the sorption hysteresis.
Wood Research 54 (4):43-56.
Rodriguez, R.J.; Sandoval, T.S.; Mendez, L.L.; Carrillo, P.A. 2011. Experimental determination and modeling of equilibrium moisture content from the sapwood of Mexican pine (Pinus pseudostrobus Lindl.). For Stud China 13 (4):285-289.
Salin, J.G. 2011. Inclusion of the sorption hysteresis phenomenon in future drying models. Some basic considerations. Maderas. Ciencia y tecnología 13(2):173-182.
Simo-Tagne, M.; Remond, R.; Rogaume, Y.; Zoulalian, A.; Perré, P. 2016. Characterization of sorption behavior and mass transfer properties of four central africa tropical woods: ayous, sapele, frake, lotofa. Maderas. Ciencia y tecnología 18(1):207-226.
Simo-Tagne, M.; Zoulalian, A.; Njomo, D.; Bonoma, B. 2011. Modelisation of desorption isotherms and estimation of the thermophysic and thermodynamic properties of tropical woods in Cameroon: the case of Ayous and Ebony woods. Revue des Energies Renouvelables (14):487-500.
Surface Measurement Systems. 2015. DVS Intrinsic System Brochure. [on line], , London, UK. [available the 6th June 2015].
Tekleyohannes, A.T. 1995. Unified and heterogeneous modeling of water vapor sorption in Douglas-fir wood with artificial neural networks. Ph.D Thesis of the University of British Columbia.
