A correlation between polymerization ratio and the hydroxyl
group amount is shown in Fig. 6(c). Generally, polymerization of
the siloxane D4 is enhanced by the hydroxyl groups on the surface
of the mesoporous aluminosilicate. This observation agrees well
with the observation made by Cabrera-Codony et al., [13] who
used active carbons as siloxane adsorbents and found that the
polymerization ratios were higher for the active carbons with relatively
high surface oxygen concentrations. In order to promote the
recyclability of the adsorbent, future work about the development
of the adsorbent with a neutral surface (minimal amount of hydroxyl
group) to prevent undesired polymerization reaction will be of
interest. Based on the findings in this study, balancing the D4
adsorption capacity and polymerization of the adsorbed D4, it is
suggested that relatively low aluminum dopant amount and a fast
heating rate should be implemented for the synthesis of mesoporous
aluminosilicate as excellent D4 adsorbents.