## 3 Results and Discussion  
### Humidity Control Experiments in Airtight Boxes  
Results of the dehumidifying performance of the aforementioned configurations at low initial humidity levels in the 70 L airtight box are given in Figure 4a, along with the corresponding temperature conditions inside the box. As can be seen from this graph, the humidity levels with the two desiccant bags and the ionic membrane configurations started at around 33% and after 20 h were reduced to around 12.9% and 4.2%, respectively. It took around 6 h for them to reach a stable humidity. After 10 h, the humidity increased slightly, which can be explained by the temperature increase, which caused the silica gel desiccants to release some of their adsorbed water (the room temperature was not controlled to replicate real operation conditions). When the combination of membrane and the two desiccant bags was used, the dehumidification rate was much faster than that of the ionic membrane or the silica gel desiccants alone. In just 2 h, the humidity decreased from 43% to 13%. After 20 h, the final humidity level was close to 6%, slightly higher than  
Figure 3: FTIR spectroscopic setup. that of the ionic membrane configuration (4.2%). Again, this can be attributed to the release of some moisture from the desiccants due to the temperature increment. When using one silica gel bag, this was found to saturate at higher humidity levels than when using two bags: 18.6% and 12.9%, respectively. By just doubling the silica gel desiccant volume, the dehumidifying rate was significantly improved. Figure 4b presents the performance of the 70 L box when starting at higher humidity levels. Starting from 72.4%, the combined configuration reduced the humidity to 22.3% in only 2 h, compared to 33% for the ionic membrane alone, a 1.5-fold better performance. The humidity levels after 20 h were similar--15% and 16%, respectively. In contrast to the previous experiment, the final humidity levels of the combined configuration were lower compared to the ionic membrane, probably due to the fact that the temperature level did not fluctuate as much. The results from an experiment involving drying using desiccants in a 70 L box with an ionic membrane are shown in Figure 5. The new dry desiccant beads were orange (Figure 5a). After exposure to humidity, they turned dark brown and green, which indicated high levels of hydration (Figure 5b). After 5 days enclosure in the 70 L box with the membrane on, these dark beads turned orange again (Figure 5c). The combined configuration provides not only superior dehumidifying performance, but also a reusable and maintenance-free solution, since the silica desiccant gel bags do not need to be replaced. Figure 4: Relative humidity and temperature in the 70 L airtight box. (**a**) Starting at low humidity levels for 1 desiccant bag, 2 desiccant bags, the ionic membrane alone and the combination of the ionic membrane and 2 desiccant bags. (**b**) Starting at elevated humidity levels, for the ionic membrane alone and the combination of the ionic membrane and 2 desiccant bags. Next, the dehumidifying performance was evaluated in a larger volume, using a 230 L airtight box (Figure 6). In this case, the four desiccant bags performed better than the ionic membrane, both in terms of their faster dehumidifying rate and final humidity levels (31.1% and 24.5%, respectively, after 40 h of operation). Again, the combined configuration outperformed the others, reaching a final humidity level of 19.6%. The use of a stronger off-the-shelf commercial ionic membrane (i.e., M-7J1R or M-10J1R, from Westisde International Ltd.) should allow for an even better control of the humidity with just a small increase in the cost. More specifically, the M-7J1R can dehumidify 16 g/day while the M-10J1R can dehumidify 29 g/day, according to the information provided by Westisde International Ltd.  
Figure 5: (**a**) Brand new silica gel desiccant (for comparison). (**b**) Silica gel desiccant exposed to humidity.