Triclosan (TCS) has been used as an antimicrobial agent for more than 30 years and is present in effluents from wastewater treatment plants, in receiving rivers, in tap water and even in groundwater. This compound is resistant to conventional water treatment processes and has been classified as endocrine disruptor and emerging concern pollutant by several organizations. For this reason it is essential to find an efficient process that allows its degradation to non-toxic substances. In this study, TiO2 was immobilized by forming thick TiO2 films on volcanic meso-porous stones, creating a photocatalyst that fills a Pyrex® CPC reactor (packed bed reactor type CPC). This reactor is used to remove aqueous Triclosan from water. Films structure and composition is determined experimentally. Efficiency of the organic molecule removal is being related with initial conditions. Films present a very high mechanical stability, excellent adhesion on stones and photocatalytic activity. Reactor, packed with covered stones, presents a reasonable pressure drop. One of the main goals is to have the reactor in operation without any solid – liquid separation step (which is quite expensive energy – demanding) and to employ locally available and inexpensive packing material for the reactor, reaching high cleaning of polluted water

En este estudio se realizaron pruebas de linealidad y de precisión, para la determinación de la Demanda Química de Oxigeno (DQO) en agua, para una adaptación a micro-escala del método de reflujo cerrado a volumen pequeño para rango alto de APHA/AWWA/WEF. El trabajo tuvo como objetivo principal el demostrar que es posible obtener mediciones adecuadas al adaptar a micro-escala el método 5220 D de APHA/AWWA/WEF, referencia de amplio uso internacional para determinar la DQO en agua. El método adaptado a micro-escala requirió solamente de cambios en la concentración de cada sustancia en la solución de digestión, pero no así en la solución catalizadora de sulfato de plata, de manera tal que la concentración de cada una de estas sustancias en los tubos de digestión fuera casi igual a aquella correspondiente al método original (exceptuando la del sulfato de mercurio, que fue reducida deliberadamente). En la adaptación a micro-escala que aquí se presenta, los volúmenes dosificados de todos los reactivos líquidos fueron medidos mediante pipetas volumétricas clase A, mejorando la precisión en las mediciones con respecto al uso tanto de pipetas graduadas como de émbolo (necesarias para efectuar el método original). Los resultados obtenidos para la adaptación a micro-escala demostraron excelente ajuste lineal y precisión del sistema.

Solar Photocatalysis is an advanced oxidation process that is involved on water detoxification as a very promising technology. This process has been used for polishing industrial and municipal wastewaters, mainly with titanium dioxide (TiO2) as a catalyst. Most of the reactors use TiO2 as a powder and need a pump in order to have the water moving through the system. A novel photocatalytic reactor, based on Compound Parabolic Collectors (CPC), was developed. The reactor has TiO2 fixed as a thick film in the CPC tubes and water flows inside by density differences exclusively. This reactor is designed to avoid catalyst separation and water pumping, steps that are energy – demanding and expensive. The films were prepared by conventional sol – gel method on 13mm diameter Pyrex tubes. The films were firmly bounded to tubes and used for several test with good efficiencies. Films had a mix of anatase and rutile crystalline phases and its particles are nanoscopic. A CPC reactor with 20 tubes connected to the tank by its upper side only was developed and used. Resorcinol was effectively removed from water, either with or without persulfate as electron acceptor, at laboratory bench (one CPC tube experiments) and at pilot scale (20 tubes in the reactor). Main reaction sub-products (tri – hydroxy benzenes) were also oxidized in reasonable solar irradiation times

A Fe3O4/HNTs composite was synthesized, characterized by XRD, FTIR, SEM, and N2 adsorption-desorption, and was used for an ibuprofen adsorption and oxidation study. The response surface methodology (RSM) and Box-Behnken experimental designs were used. The effect of pH, contact time, IBU concentration, and Fe3O4/HNTs dosage on ibuprofen adsorption were evaluated. Additionally, adsorption isotherms and a kinetic study were performed. The effect of pH, H2O2 concentration, and Fe3O4/HNTs dosage for IBU oxidation were also studied. The results of ibuprofen adsorption on Fe3O4/HNTs indicate that adsorption was favored at acidic pH. The adsorption followed pseudo-second-order kinetics and a Freundlich isotherm. A 99.99% IBU oxidation and 99% mineralization were achieved at pH 7, Fe3O4/HNTs dosage of 1.5 g L-1, and 0.5 M H2O2. The Fe3O4/HNTs catalyst prepared in this study was efficient in removing aqueous ibuprofen through heterogeneous Fenton-like reaction.