Experimental-design-guided approach for the removal of atrazine by sono-electrochemical-UV-chlorine techniques

ABSTRACT

The aim of the present study was to investigate the electrochemical formation of free chlorine species (HOCl/ClO⁻) and their subsequent use for the degradation of the pesticide atrazine. Initially, the process of electrochemical-free chlorine production was investigated using a bench-scale electrochemical flow-cell. The most significant variables (electrolyte concentration ([NaCl]) and inter-electrode gap) of the process were obtained using a 2³ factorial design and the optimum process conditions (1.73 mol L⁻¹ and 0.56 cm) were determined by a central composite design. Following optimization of free chlorine production, three degradation techniques were investigated, individually and in combination, for atrazine degradation: electrochemical, photochemical and sonochemical. The method using the techniques in combination was denominated sono-photo-assisted electrochemical degradation. Constant current assays were performed and the sono-photo-assisted electrochemical process promoted more efficient removal of atrazine, achieving total organic carbon removal of ∼98% and removal of atrazine to levels below the detection limit (>99%) in under 30 min of treatment. Furthermore, the combination of three techniques displayed lower energy consumption, and phytotoxicity tests (Lactuca sativa) showed that there was no increase in toxicity.

KEYWORDS:

• Electrochemical advanced oxidation processes
• chlorine photolysis
• UV/Cl₂
• free chlorine species
• atrazine

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors would like to thank the support from the funding agencies Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP - 2014/02739-6); Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG).