Propriedades ópticas da água - identificação de contaminantes contidos por espectroscopia de transmissão

Abstract

The relevance of the compound of water is an unquestionable fact and its properties are influenced, or not, by the presence of certain substances. Pure water is a substance with uncommon characteristics indicating physical properties and a sufficiently differentiated behavior. For being a dipole molecule, of hydrogen bonding intermolecular forces, water therefore presents several anomalous properties. Its boiling point would have to be –200ºC, once its behavior as molecules of similar molecular weight. Other properties should also be emphasized such as viscosity, superficial tension and specific heat in elevated values, other than polar substance solubility, ionic and also nonionic. These peculiar characteristics define water as a universal solvent, and in this matter attacked by the excretion of a great variety of industrial and anthropogenic pollutants. Residues such as heavy metals (Mg, Pb, Hg, Fe, Al, Mn, Cd, Zn, Ni, Cr) Cyanides, Phenols, oils and lubricants, ammonia, sulfides, fecal coliforms, Cyan Toxins. In this study we analyzed distilled, potable and contaminated water samples in order to obtain the identification of enclosed substances. Through optical properties based on proper spectra of water and of the substances, already accomplished by other science staffs, we searched to detect the absorption peaks and characteristic emission of the components added to the water. Making use of the Spectroscopic Transmission experimental technique in the near infrared region (NIR) and the optical entirety of the SPECORD 61NIR with necessary peripherical adaptations, we analyzed samples of potable water, pure distilled water and intentionally contaminated with: Chlorine, Monobasic Potassium Phosphate, Sodium Nitrate, Ethanol, brake fluid, Gasoline, Oil Lubricant and diesel fuel. Justified by the adjacent technical obstacles withi n a research, it was not possible to identify characteristical peaks of all the mentione d substances, but this study achieved the general objective to provide a scientific instrument for the near ecological studies employing absorption and emission spectroscopy and the specificity of identifying some substances added to water.