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Sensores potenciométricos, amperométricos e condutométricos são sensores eletroquímicos com imensa aplicação nas áreas de meio ambiente, indústria e análises clínicas. O presente trabalho apresenta uma revisão generalizada dos aspectos fundamentais, os desenvolvimento e a contribuição destes sensores na área de química analítica, e reporta alguns aspectos relevantes dos avanços na área de sensores eletroquímicos no Brasil.Potentiometric, amperometric and conductometric electrochemical sensors have found a number of interesting applications in the areas of environmental, industrial, and clinical analyses. This review presents a general overview of the three main types of electrochemical sensors, describing fundamental aspects, developments and their contribution to the area of analytical chemistry, relating relevant aspects of the development of electrochemical sensors in Brazil.

Recebido em 7/10/98; aceito em 31/3/99 TEXTILE DYES. A dye is a colored substance used to impart permanent color to other substances. Its most important use is in coloring textile fibers and fabrics. The removal of colour from dyehouse waste waters is currently a major problem in the textile sector. This paper provides an overview of the treatment technologies that can currently be used by the textile processor and the developments over the past decade with respect to the toxicological and ecotoxicological properties of synthetic organic dyes.

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The great versatility of semiconductor materials and the possibility of generation of electrons, holes, hydroxyl radicals, and/or superoxide radicals have increased the applicability of photoelectrocatalysis dramatically in the contemporary world. Photoelectrocatalysis takes advantage of the heterogeneous photocatalytic process by applying a biased potential on a photoelectrode in which the catalyst is supported. This configuration allows more effectiveness of the separation of photogenerated charges due to light irradiation with energy being higher compared to that of the band gap energy of the semiconductor, which thereby leads to an increase in the lifetime of the electron-hole pairs. This work presents a compiled and critical review of photoelectrocatalysis, trends and future prospects of the technique applied in environmental protection studies, hydrogen generation, and water disinfection. Special attention will be focused on the applications of TiO 2 and the production of nanometric morphologies with a great improvement in the photocatalyst properties useful for the degradation of organic pollutants, the reduction of inorganic contaminants, the conversion of CO 2 , microorganism inactivation, and water splitting for hydrogen generation.

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