Chemistry

A Light for the Cure

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Science  27 Jul 2007:
Vol. 317, Issue 5837, pp. 427
DOI: 10.1126/science.317.5837.427b

Zeolites are mesoporous minerals used as ion-exchange beds in water purification and softening, and as chemical reaction platforms. Pure silica zeolites have been grown as polycrystalline films on nonporous supports, but the potential utility of these materials depends on their hydrophobicity and porosity, which in turn depends on the presence of grain boundaries. Post-deposition treatments have been used to remove the hydrophilic silanols that form, but typically these approaches either fail to penetrate the pore structure or fail to stand up to the heating required to remove the organic template used during zeolite growth.

Eslava et al. show that strong ultraviolet (UV) irradiation during the heating process induces hydrophobicity while also improving the pore structure by creating smaller pores with a narrower distribution. They deposited suspensions of the zeolite silicalite-1 that had been mixed with tetrapropylammonium (TPA) as the organic templating material. UV irradiation during calcination induced methylation by TPA fragments, as well as condensation of polar silanol groups. Film cracking and delamination effects common in other nanocrystalline systems were also suppressed. — MSL

J. Am. Chem. Soc. 129, 10.1021/ja0723737 (2007).

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