Synthesis and regeneration of polyurethane/adsorbent composites and their characterization by adsorption methods

Composite polyurethane/adsorbent materials were synthesized with various adsorbents: two activated carbons, one zeolite and one pillared clay. The distribution of the adsorbents and the effect of their concentration in the polymeric matrix were studied. The results indicated that activated carbons had a better distribution than the inorganic adsorbents. For concentrations above 13% the adsorbent materials were found to have a significant negative influence on the properties of the polyurethane foam, impairing their use. The thermal regeneration of the composite materials and the recycling of the adsorbents were also studied. The composite materials were regenerated under nitrogen flux and characterized by low temperature nitrogen adsorption. The regeneration of the composite materials was possible only in the cases where the activated carbons were the adsorbents, for which no significant loss of adsorption capacity was observed, contrary to when the inorganic materials were used. The recycling of the adsorbent materials from the polymeric matrix, under air flux, was only possible in the case of the inorganic adsorbents, the zeolite being the more favorable case. An adsorption model developed in this work could predict the toluene adsorption isotherm on the composite material, and the results were compared with the experiment. This model is based on the combination of the Flory–Huggins and Dubinin–Astakhov models, for the adsorption on the polyurethane foam and on the adsorbent material, respectively, and could successfully predict the toluene adsorption, used in this work as a probe for the adsorption of volatile organic compounds.