ABSTRACT Ozone is a strong oxidant used in the water treatment to remove organochloride compounds. Given that many processes of degradation generate chemical compounds that are more toxic than initial compounds, the development of optimized ozonation processes are required. In this study, pentachlorophenol (PCP) was used as a model of an organochlorine compound and the toxicity of its degradation products generated by both non-catalytic and catalytic ozonation processes were evaluated with a fresh-water Daphnia magna (ecotoxicity) and vegetables species Lactuca sativa and Panicum millaceum (Phytoxicity). The catalytic ozonation used MnO2/TiO2 as catalyst, which was characterized by X-ray diffraction analysis showing the presence of crystalline TiO2 phases, rutile and anatase. The specific BET surface area of MnO2/TiO2 was 43 m2/g. It was found that the use of ozone as an oxidant showed a first order degradation rate constant (kobs = 0.5 ± 0.1 min-1). The uncatalyzed reaction showed several reaction intermediates like mono- and polychlorinated phenols, and quinones. The oxidation of these compounds led to low molecular weight organic acids. From these results, we proposed a pathway of PCP degradation using ozone. The catalyzed reaction showed a more potent effect in reducing the toxicity of the treated solution. Unlike the use of only ozone which does not decrease the toxicity. It was found that the treatment with catalytic ozonation decreases the toxicity of the solutions.

The clinical case presented in this article illustrates the combination of multiple surgical techniques geared to the prosthetic rehabilitation of an edentulous patient for the treatment of an atrophic upper jaw with an onlay type iliac crest autologous graft. Treated patient was a 60 year old female presenting a type IV Cawood and Howell atrophic alveolar process. Therefore, treatment conducted was reconstruction of the alveolar process with an iliac crest autologous graft.

El caso clínico que se muestra ejemplifica la conjunción de múltiples técnicas quirúrgicas con el objetivo de rehabilitar protésicamente a un paciente desdentado, para el tratamiento del maxilar superior atrófico con injerto autólogo de cresta iliaca anterior tipo onlay. Se trata de paciente del sexo femenino de 60 años de edad, la cual presenta un proceso alveolar atrófico tipo IV de Cawood y Howell, por lo que se realiza la conservación y reconstrucción de proceso alveolar con injerto autólogo de cresta iliaca.

As estruturas dos produtos de degradação mediada por ozônio de diferentes compostos farmacêuticos foram estudadas. Uma completa degradação do nadolol foi observada nas condições empregadas após 100 min. Os produtos de degradação obtidos nas soluções aquosas foram caracterizados por espectrometria de massas com ionização por electrospray (ESI-MS e ESI-MS/MS). O mecanismo proposto para a degradação consiste inicialmente do ataque de ozônio ao grupo amino da anilina formando nitro compostos, seguida de uma série de processos oxidativos. Monitoramento por ESI-MS(/MS) mostrou que a degradação de atenolol (ATE) e acebutolol (ACE) por ozônio ocorrem via um mecanismo similar ao do nadolol

The structures of intermediate products of ozone degradation of different pharmaceutical compounds have been studied. Under the conditions employed, complete ozone degradation of nadolol was achieved after 100 min. The degradation products obtained in aqueous solution were characterized by electrospray ionization mass (and tandem mass) spectrometry (ESI-MS and ESI-MS/MS). The proposed mechanism for degradation, ozone attacks at the aniline amino group giving rise to nitro compounds and further degradation occurs via a series of oxidative processes. Continuous online monitoring by ESI-MS(/MS) with high accuracy mass measurements showed that ozone degradation of atenolol (ATE) and acebutolol (ACE) occurs via mechanisms similar to that of nadolol

The degradation of two â-blockers, atenolol and nadolol (50 ppm), was conducted using ozonation. At the working conditions, pH 3, 7 and 9, a degradation of 90% for nadolol and about 60% for atenolol was achieved after one hour of reaction. The main degradation products were identified as low molecular weight organic acids. The relative toxicity of the solutions was evaluated using the Daphnia magna test. It was found that the toxicity of the treated solutions, under all the working conditions, was lower than the toxicity of the initial solution. The biggest decrease in toxicity was obtained at pH = 9.

La degradación de dos â-bloqueadores atenolol y el nadolol (50 ppm) por ozonización fue realizada. En las condiciones de trabajo utilizadas, a diferentes condiciones de pH 3, 7 y 9, se logró una degradación mayor al 90% para nadolol y alrededor del 60% para atenolol al cabo de una hora de reacción. Se determinaron los productos de degradación mayoritarios siendo éstos ácidos orgánicos de bajo peso molecular. La toxicidad relativa de las soluciones fue evaluada utilizando el ensayo de Daphnia magna. La toxicidad de las soluciones tratadas, en todas las condiciones de trabajo, fue menor que la toxicidad de la solución inicial. El mayor descenso de toxicidad se obtuvo a pH = 9.

The catalytic ozonation of oxalic acid in a batch reactor using TiO2, MnO2/TiO2 and Rh/TiO2 as catalysts was studied. The presence of the catalyst significantly improves the ozonation rate in comparison with the non-catalytic reaction. The adsorption and the extent of degradation of oxalic acid were found to be dependent on the solution's pH. Higher degradation rates were found for catalytic systems at pH 2.5, where the oxalic acid concentration in the water phase was almost completely removed. The contribution of the MnO2/TiO2 and Rh/TiO2 catalysts as well the TiO2 support is discussed. The highest mineralization, expressed as CO2 evolution, was reached with the MnO2/TiO2 catalyst at pH 2.5

A methodology to decrease the chromium concentration Cr(VI) existing in tannery discharges is suggested. The proposal is based on a photocatalytic process in which the effluent is irradiated by UV light in presence of TiO2 as a catalyst employing formaldehyde as a reductor agent. Were employed different Cr(VI) solutions of 100 mg/L as models at different pH, catalyst quanties and irradiation times. The variable optimization was made from multivaried analysis. The better conditions for to reduction a 50 ml of a Cr(VI) of 100 mg/L solutions were pH 2 at 20 minutes of UV irradiation and 40 mg of TiO2 load. In these conditions it was possible a 97.8 % of Cr(VI) reduction level. For a real effluent from tannery industries the reduction level was 81.3 %.

Se propone una metodología para disminuir la concentración de Cr(VI) presente en efluentes de curtiembre sin tratamiento previo. La propuesta se basa en un proceso fotocatalítico donde se irradia el efluente por un determinado tiempo con luz ultravioleta en presencia de óxido de titanio como catalizador, empleando como agente reductor formaldehido. Se utilizó sistemas modelo de soluciones de Cr(VI) de 100 mg/L a distintos pH con diferentes cantidades de catalizador y tiempos de irradiación. La optimización de las variables se realizó a través de análisis multi-variado Las condiciones óptimas para reducir 50 ml de Cr(VI) de 100 mg/L, se obtuvo a pH 2, con un tiempo de irradiación de 20 minutos y 40,0 mg de TiO2, logrando para el sistema modelo un 97,8 % de reducción de Cr(VI) y para el efluente de curtiembre un 81,3 %.