No abstract

Little is known about how the variation in crystallite size of zeolites affects acidity. There is currently a tendency to decrease the size of materials because of the resulting improvements...

Nuevos complejos de titanio de fórmula general Ti(OAr)4•HOR con diferente grupo sustractor (Cl,CN, NO2), se sintetizaron por el método intercambio alcohol-fenol y se caracterizaron por resonancia magnética nuclear (1H NMR) que dio evidencia de la formación de estructuras diméricas con centros de Ti coordinado octaédricamente; y por análisis termogravimétrico (TGA) que registró pérdida de volátiles y permitió ajustar el peso molecular experimental de cada pre-catalizador. Mediante el análisis químico por absorción atómica se determinó el porcentaje elemental de aluminio en el co-catalizador de composición trietilaluminio. Los complejos de Ti en presencia de trietilaluminio se evaluaron en la reacción de dimerización de etileno a 50 °C, presión atmosférica y con flujo de etileno igual a 100 mL/min donde se observó en todos los catalizadores actividad hacia la producción de 1-buteno.

A chromate of copper and cobalt (Φy) was synthesized and characterized. Φy activated peroxymonosulfate (PMS) to degrade ciprofloxacin (CIP) in water. The Φy/PMS combination showed a high degrading capability toward CIP (~100% elimination in 15 min). However, Φy leached cobalt (1.6 mg L−1), limiting its use for water treatment. To avoid leaching, Φy was calcinated, forming a mixed metal oxide (MMO). In the combination of MMO/PMS, no metals leached, the CIP adsorption was low (<20%), and the action of SO4•− dominated, leading to a synergistic effect on pollutant elimination (>95% after 15 min of treatment). MMO/PMS promoted the opening and oxidation of the piperazyl ring, plus the hydroxylation of the quinolone moiety on CIP, which potentially decreased the biological activity. After three reuse cycles, the MMO still presented with a high activation of PMS toward CIP degradation (90% in 15 min of action). Additionally, the CIP degradation by the MMO/PMS system in simulated hospital wastewater was close to that obtained in distilled water. This work provides relevant information on the stability of Co-, Cu-, and Cr-based materials under interaction with PMS and the strategies to obtain a proper catalyst to degrade CIP.