Remoção de Chumbo e Bário de um efluente aquoso sintético via eletroflotação/eletrocoagulação

Abstract

The traditional techniques for wastewater treatment do not show satisfactory results when dealing with very low concentration of heavy metals and large volumes, mainly due the low operational efficiency and high extraction costs. Therefore, ionic flotation thechniques have been studied as an alternative method to deal with these effluents since it constitutes in a simple and efficient process that can be used in small, medium or large scale. The use of Electroflotation consists on a separation of ions or solid particles from a liquid phase by using rising bubbles formed during the water electrolysis. It adds advantages to the flotation, for example: the electrode selection allows the design of system for an specific process, soluble anodes, as iron or aluminum, generate coagulants agents in situ, avoiding the addition of coagulants during the process and the variations of the current density in the electrodes implies in different amount of micro bubbles, increasing the collision probability between the particles and the bubbles. The objective of this work is to study the main physical chemistry parameters that affect the electroflotation and electrocoagulation process of a synthetic solution that contains initially 15mg/L of lead and barium. The parameters investigated were: pH, current density, ionic strength and process time. The results showed that the electroflotation applied on the experimental apparatus proposed was able to achieve satisfactory results on the lead and barium removal within the range studied. At all pH ranges studied in the presence of sodium dodecyl sulfate in a ratio metal/colligant 1/3, current of 1.4 A, ionic strength 3,2.10-3 M and twenty minutes of flotation, it was possible to reach emission standards for effluents containing lead and barium, described in the local environmental regulation Law, Resolution CONAMA 357.