Sorption behavior of four tropical woods using a dynamic vapor sorption standard analysis system
Résumé
Sorption behavior of four tropical woods coming from Cameroon is studied using a Dynamic VaporSorption-Intrinsic apparatus. Sorption isotherms at 20°C and 40°C ofTriplochiton scleroxylon(obeche),Entandrophragma cylindricum (sapele), Sterculia rhinopetala (lotofa) and Terminalia superba (frakealso called limba) are compared to those in the literature with methods using saturated salts for lotofaand 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, differencesin the hysteresis of sorption among the woods decreases. Hystereses of all studied woods rangedfrom 0,5 to 3%. Our studied woods have lower equilibrium moisture content probably caused by thehigher values of extractives content. The water sorbed molecules on multilayer during both adsorptionand desorption at 20°C and 40°C is greater in the case of frake and lower in the case of lotofa. Thewater sorbed molecules on multilayer of sapele is greater than those of obeche. The predominance ofmultilayer over monolayer of our woods is from 0,2 to 0,4 relative humidity in adsorption phase, andfrom 0,3 to 0,4 relative humidity in desorption phase.
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