From the experiment “Adsorption”, the breakthrough concentration curve is not similar S-curve, a one reason; the moisture measuring device (hygrometer) is not very stable, it gets often errors. That causes the moisture measuring which is very sensitive, does not be with the actual. The others factor of errors can be taken place from bad preparing o fresh silica gel (adsorbent), heat can regenerate the silica gel, then adsorbent in the pack bed get still little hot. The hot adsorbent would adsorb and regenerate simultaneously, so the values from hygrometer may be different by the actual ones.
From calculation and analysis from the figure1 shows tb and t* are 60.41 min and 68.30 min, respectively. There are differences of the values from the experiment and the calculation. The previous factors can be described them. Mass transfer zone is very wide, that means the beds get low efficiency. The equivalent lengths of unused base (LUB) would be defined when the all silica gel are saturated or the concentration of air is no longer change (c=c0). Experimenters stop the lab when the values by hygrometer approach to constant, but it still very slowly increase. That causes the equivalent lengths of unused base from experiment is less than calculation.