SIMULATION OF ATRAZINE DEGRADATION BY IN SITU ELECTROCHEMICALLY GENERATED OZONE FOR GROUNDWATER REMEDIATION / SIMULAÇÃO DA DEGRADAÇÃO DE ATRAZINA COM OZÔNIO GERADO ELETROQUIMICAMENTE IN SITU PARA REMEDIAÇÃO DE ÁGUAS SUBTERRÂNEAS

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

The impact of pesticides on the quality of groundwater has been the subject of scientific and public health concerns in the entire planet, especially in areas where groundwater is mainly used for human consumption. The intensive use of pesticides in agriculture and the high persistence of several of these chemicals have required a rigorous control of possible environmental contaminations, especially of drinking water sources. The herbicide atrazine is frequently detected in natural waters of many countries and was selected for investigation. A laboratory scale study on the evaluation of the effectiveness of remediation of atrazine in groundwater utilizing in situ electrochemical generated ozone was conducted. ¿-PbO2 was used as anode for ozone generation. ¿-PbO2 electrodes were prepared by electrodeposition on Ti plates. X-ray diffraction analysis confirmed that the deposit contained only the ¿ and ¿ PbO2 with the ¿ phase prevailing. The electrochemical ozone production increases with incrementing the current density. The rate of ozone production during the electrolysis was 4.4, 19.5 and 39.1 mg h-1 for current densities of 0.5, 1.0 and 1.50 kAm(-2), respectively. In the experiments of atrazine degradation by electrochemically generated ozone a difference in atrazine degradation was found when the applied current density was varied. The results evidenced that the atrazine degradation rates increased with augmenting the current density. This is indicative of a greater oxidation ability of the anode with increasing the current applied due to the production of more electrogenerated active oxidant (O3/.OH). The kinetic analysis of the above results related to different reaction orders gave good linear correlations when the data was fitted with a pseudo first-order reaction rate equation. The pseudo first-order rate constants obtained were 6.2×10(¿3), 8.8×10(¿3), and 1.21×10(¿2) min(¿1) for 0.5, 0.1, and 1.5 kA m(¿2), respectively. The acrylic column (26 cm x 4 cm ID) used in flow degradation experiments was packed with clean sand and contained a single set of electrodes. Two expanded titanium mesh coated with ¿-PbO2 and RuO2 served as anode and cathode, respectively. During the experiments the atrazine effluent concentration progressively diminished. After 8 hours of electrolysis the effluent atrazine concentration was reduced by 75% and 80% applying current densities of 0.4 and 0.6, respectively. These results confirm the potential applicability of this type of groundwater plume control strategy. The study constitutes a foundation to the future developing of this aquifer remediation technique.

ASSUNTO(S)

remediacao groundwater electrooxidation agua subterranea eletrooxidacao remediation atrazina ozone atrazine ozonio

ACESSO AO ARTIGO

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