Alvarez-Aguiñaga Edith A, Elizalde-González María P, Sabinas-Hernández Sergio A
Centro de Química, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Ciudad Universitaria Edif. IC7 Puebla Pue. 72570 Mexico
Instituto de Física, Benemérita Universidad Autónoma de Puebla PO Box J-48 Puebla Pue. 72570 Mexico.
RSC Adv. 2020 Oct 26;10(64):39251-39260. doi: 10.1039/d0ra06421a. eCollection 2020 Oct 21.
Zeolites are not often used directly as photocatalysts. Their framework and nanocavities have served as support or hosts for photoactive materials or traces of transition metals functioning as photoactive sites for catalysing decomposition and oxidation reactions in the gas phase. Research in this area has been limited to a few synthetic zeolites and in this context, efforts are directed to the preparation of new zeolite-based photocatalysts, when in nature there is an abundance of materials with properties yet to be discovered. We report the application of a natural clinoptilolite-mordenite zeolite as an efficient self-photocatalytic material for the decomposition of caffeine in aqueous solution. Adsorption experiments, combined with textural, crystallographic, and spectroscopic characterization were performed comparatively for the natural zeolite, a synthetic homologue, and the iron-exchanged zeolite. The neat zeolite containing 1.2 wt% of endogenous iron exhibited 99% decomposition of caffeine after 4 h irradiation and a faster reaction rate, followed by the synthetic sample. In contrast, the iron-loaded sample was the less effective zeolite because of pore blocking. Caffeine adsorption occurred on the outer zeolite surface and the photoproducts were hydroxylated pyrimidine rings and linear amide derivatives.
沸石通常不直接用作光催化剂。它们的骨架和纳米腔已作为光活性材料的载体或宿主，或作为光活性位点的过渡金属痕迹，用于催化气相中的分解和氧化反应。该领域的研究仅限于少数几种合成沸石，在此背景下，人们致力于制备新型的沸石基光催化剂，而自然界中存在大量具有尚未被发现的性质的材料。我们报道了天然斜发沸石-丝光沸石作为一种高效的自光催化材料在水溶液中分解咖啡因的应用。对天然沸石、合成同系物和铁交换沸石进行了吸附实验，并结合结构、晶体学和光谱表征进行了比较。含有1.2 wt%内源性铁的纯沸石在照射4小时后咖啡因分解率达99%，且反应速率更快，其次是合成样品。相比之下，负载铁的样品由于孔堵塞而效果较差。咖啡因吸附发生在沸石外表面，光产物是羟基化嘧啶环和线性酰胺衍生物。
