Water pollution by pharmaceuticals is a current worrying environmental problem. Adsorption and catalytic processes using zeolites have been employed in several studies to remove/degrade pharmaceuticals from water. The interest of researchers in these two strategies based on the utilization of zeolites (i.e., adsorption and advanced oxidation technologies, AOT) is continuously growing. Then, this work presents a literature review, considering the origin of the zeolites (natural vs. synthetic) and the modifications of zeolites (e.g., the addition of surfactants) for the adsorption of diverse pharmaceuticals. The role of zeolites in catalytic ozonation, Fenton-based systems, and activation of peroxymonosulfate and peroxydisulfate is detailed. Also, the primary transformations of pharmaceuticals induced by these AOTs were examined. Moreover, the gaps regarding biodegradability and toxicity of the transformation products coming from the degradation of pharmaceuticals by the zeolites-based processes were discussed. To overcome the scarcity of information regarding the biodegradability and toxicity of the primary transformation products observed in the revised works, an initial approach to these topics, using a predictive tool, was made. Finally, from the present review, it was evidenced the need for future works involving zeolites that provide results about the simultaneous removal/elimination of multiple pharmaceuticals in complex matrices (e.g., hospital wastewater or municipal wastewater), new information about biodegradability and toxicity plus the development of combination or coupling of processes with other AOTs (e.g., sonochemistry) or classical systems (e.g., biological process).

En este artículo se describe el proceso de síntesis de zeolitas LTA y/o FAU a partir de residuos obtenidos de la industria minera y manufacturera de Antioquia (Colombia), y su uso para la remoción de Cr (III). Los residuos industriales fueron caracterizados por Fluorescencia de Rayos X y Difracción de Rayos X. Así mismo, las zeolitas sintetizadas a partir de estos residuos se caracterizaron por medio de Difracción de Rayos X, Fluorescencia de Rayos X, Espectroscopía Electrónica de Barrido (SEM) y Área BET. Por otra parte los datos de adsorción en el equilibrio para la remoción Cr (III) utilizando las zeolitas sintetizadas, fueron obtenidos por espectroscopia de adsorción atómica, y ajustados a los modelos de adsorción Langmuir, Freundlich y Temkin, y cuatro modelos cinéticos. Los resultados indicaron la obtención de zeolitas a partir de residuos industriales eficientes en las pruebas de adsorción de Cr (III).

In this paper zeolite Beta was synthesized and characterized by XRD, ATG, ATD, XRF and SEM. Subsequently various modifications were made using a surface passivation process in liquid phase with tetraethylorthosilicate (TEOS), using two loads of TEOS and three passivation cycles, in order to obtain six catalysts. These materials were characterized by NH3-TPD and tested in tolune disproportionation reaction, under different conditions of pressure and temperature. As modification cycles were increased for each catalyst, there was a change in the acidity of the solids, mainly due to deposition of an inert layer of silica on the external surface. These results were confirmed with the improvement in para-selectivity and decreasing in conversion. Despite zeolite Beta is a large pore zeolite, an improvement of the para-selectivity was obtained, achieving almost stable values for the entire range of temperature and pressure conditions.

The hydrothermal method was used for the synthesis of lamellar chromates and vanadates of Cu and Ni (ΦY and ΦZ -types), which served as precursors for the subsequent synthesis of mixed metal oxides (MMO). These MMOs (named as CuV MMO, NiV MMO, CuCr MMO, and NiCr MMO) were characterized and evaluated for the catalytic oxidation of toluene, showing activity at temperatures below 400 °C. Among the studied materials, CuCr MMO demonstrated superior catalytic activity compared to CuV MMO, NiCr MMO, and NiV MMO, due to the higher reducibility of Cu or Cr in these materials. The temperatures required to achieve 90% conversion of toluene (T90) followed the order CuCr MMO (~275 °C) < CuV MMO (~330 °C) < NiV MMO (~370 °C) < NiCr MMO (~395 °C). Furthermore, the incorporation of Co to CuCr MMO (which produced CoCuCr MMO) significantly improved the catalytic performance, leading to toluene oxidation at even lower temperatures, T90: ~265 °C. For comparison, the MMO derived from the lamellar precursor exhibited superior catalytic performance relative to that obtained via simple mixing and calcination of the corresponding inorganic metal salt. This result highlights the relevance of the precursor’s structure in the subsequent catalytic activity. Finally, a stability test was performed on the best-performing catalytic material (CoCuCr MMO). Toluene conversion remained at ~100% for the first 4 h, then decreased to ~45%, remaining stable for up to 70 h of continuous reaction.