Avaliação da remoção de fosfato de solução aquosa pela eletrocoagulação utilizando eletrodos de zinco

Abstract

Phosphate (PO4-3) is a polyatomic ion formed by one atom of phosphorus and four of oxygen. We Find phosphate rocks and in certain foods, it plays an important role in biological processes and can also be used as an agricultural fertilizer. The offer of phosphorus in water bodies takes place in different ways. However, the increase in the concentration of phosphorus and nitrogen in water bodies can stimulate the eutrophication of these environments. It is considered that the discharge of industrial and domestic effluents into water bodies provides a favorable environment for eutrophization, therefore, electrocoagulation (EC) has been shown to be an efficient method for removing contaminants from water bodies. Through the oxidation of sacrificial anodes and water cathodic reduction, coagulants are formed in situ, leading to adsorption of pollutants in the formed coagulants. In the present research, the EC process for phosphate removal was applied to Zn anode and cathode in aqueous solution, in which the electrodes were connected to a direct current power source. For the optimization of the process, a 22 factorial experimental design was carried out to evaluate the initial pH (pHi) and current density (j) variables, having as a response the phosphate removal efficiency after 60 min of treatment, being applied to the statistical model the removal results observed at 15 min. NaCl was added as supporting electrolyte at a concentration of 500 mg L-1 which proved to be satisfactory for carrying out the experiment. The phosphate removal efficiency at 15 min was 97.15% observed at pHi = 4.0, j = 9.01 mA cm-2 in 50 mg L-1 phosphate with Zn electrodes. When the same conditions were applied in raw effluent, the phosphate removal reached 97.15% at 50 minutes. The results obtained indicate that, under the operational conditions studied, electrocoagulation applied to raw effluents from corn flour industries can be used as a pre-treatment for phosphate removal using Zn electrodes.