Effects of Mass Transfer Mechanisms on the Kinetics of Water Uptake By Henna Powder

Kinetics of water sorption by the henna powder was measured experimentally in two types of chambers# the chambers were a “static chamber” containing stationary air with controlled temperature and humidity and a “dynamic chamber” in which dynamic air flowed through the samples, with controlled air temperature, humidity, and flow rate# water uptake by the samples placed in the chambers was measured along the time# according to the results, the water uptake by the powder was faster in the dynamic chamber in comparison with the static one but the equilibrium amount of water uptake was the same for both# actually, different conditions (stationary and moving air) lead to different mechanisms of mass transfer and consequently different kinetic rates of water uptake were observed# however, the thermodynamic makes both of the conditions equal at the equilibrium state#