Uso de adsorventes para a remoção de poluentes em museus

Studies on the adsorption of acetic acid by activated carbons, zeolites and other adsorbent materials related with the preventive conservation of lead objects in museums showcases

To test the suitability of adsorbents such as activated carbons, zeolites, and other materials to adsorb acetic acid vapours that are liberated inside museum showcases and may destroy lead objects, the adsorption capacities at the saturation pressure and the isotherms of adsorption at lower pressures were determined. The results obtained show that the NaX zeolite in pellet form and the RB4 activated carbon are the best adsorbents. Additionally, they show that materials with sodium content exhibit an exchange process that may be very important, particularly in the case of NaX zeolite. Some of the parameters determined (saturation capacity, Henry constant, kinetic parameter) seem to be related in a simple manner (although there are adsorbents that do not agree with the general trend). However, it was not found a simple relation between the specific surface area previously determined with nitrogen at 77 K and the acetic acid saturation capacity at room temperature.

Resumo de:

António João Cruz, João Pires, Ana P. Carvalho, M. Brotas de Carvalho, “Studies on the adsorption of acetic acid by activated carbons, zeolites and other adsorbent materials related with the preventive conservation of lead objects in museums showcases”, Journal of Chemical and Engineering Data, 49(3), 2004, pp. 725-731.

Artigo completo:

http://dx.doi.org/10.1021/je034273w
[acesso condicionado]

 

Physical adsorption of H₂S related to the conservation of works of art: the role of the pore structure at low relative pressure

The adsorption isotherms of H₂S in selected adsorbents were determined at 298 K, at relative pressures up to about 0.005, aiming the use of these materials in the removal of that pollutant from the museums atmosphere. The Dubinin-Astakhov equation adjusts very well the experimental results, although one cannot interpret the pre-exponential factor w₀ as the limiting adsorbed amount. The parameter E, related with the adsorption energy, and the parameter n, that can be associated with the surface heterogeneity of the adsorbents, are correlated and the first is also correlated with the adsorbed amounts. It was not found any expectable relationship between the adsorbed amounts and textural parameters of the adsorbents such as the specific surface area or the microporous volume. This points out that the adsorption of H₂S is highly specific. In general, 13X and Y sodium zeolites seem to be the most effective adsorbents, but at lowest tested pressures, near the concentrations found at museums, a pillared clay prepared from a Wyoming montmorillonite seems to be more efficient.

Resumo de:

António João Cruz, João Pires, Ana P. Carvalho, M. Brotas de Carvalho, “Physical adsorption of H₂S related to the conservation of works of art: the role of the pore structure at low relative pressure”, Adsorption, 11(5-6), 2005, pp. 569-576.

Artigo completo:

http://dx.doi.org/10.1007/s10450-005-5614-3
[acesso condicionado]