Unexpected toxicity decrease during photoelectrochemical degradation of atrazine with NaCl

Abstract

This report shows an unexpected toxicity decrease during atrazine photoelectrodegradation in the presence of NaCl. Atrazine is a pesticide classified as endocrine disruptor occurring in industrial effluents and agricultural wastewaters. We therefore studied the effects of the degradation method, electrochemical and electrochemical photo-assisted, and of the supporting electrolyte, NaCl and Na 2 SO 4 , on the residual toxicity of treated atrazine solutions. We also studied the toxicity of treated atrazine solutions using Artemia nauplii. Results show that at initial concentration of 20 mg L -1 , atrazine was completely removed in up to 30 min using 10 mA cm -2 electrolysis in NaCl medium, regardless of the electrochemical method used. The total organic carbon removal by the photo-assisted method was 82% with NaCl and 95% with Na 2 SO 4 . The solution toxicity increased during sole electrochemical treatment in NaCl, as expected. However, the toxicity unexpectedly decreased using the photo-assisted method. This finding is a major discovery because electrochemical treatment with NaCl usually leads to the formation of toxic chlorine-containing organic degradation by-products.

Combined soil washing and CDEO for the removal of atrazine from soils

“…Atrazine is one of the most applied pesticides and it has been the focus of several researches [12,[30][31][32][33][34][35] because of its low biodegradability, long half-life and low solubility in water (33 mg dm −3 at 22 • C). This work aims to evaluate the effectiveness of a complete treatment of a soil spiked with atrazine, consisting of the soil washing with a sodium dodecyl sulphate solution followed by the electrolysis with BDD anodes of the resulting wastewater.…”

Removal of pesticide 2,4-D by conductive-diamond photoelectrochemical oxidation

“…Many works in the literature study the combination of UV light irradiation and electrolysis for the removal of pollutants such as dyes [13][14][15], pharmaceutics [16], pesticides [17,18], phthalates [19], organic polymers [20] and leachate [21]. Results shown in those works indicated improvement in the removal rates explained by heterogeneous and homogenous catalytic processes related to activation of oxidants.…”

Electrochemical degradation of tetracycline in artificial urine medium

“…This kind of anode is very electrocatalytic for the generation of active chlorine species or active chlorine (Cl 2 , HOCl, and OCl − ) in chloride-containing medium [24][25][26]. Several studies have shown that when using dimensionally stable anodes in the presence of chloride ions, the removal efficiency of organic compounds, such as atrazine [27], mixtures of phenol and formaldehyde [28], oxytetracycline [29], and oxalic acid [25], were considerably increased. It should be noted that chloride ions are naturally present in various environmental matrices and, thus, can increase the efficiency of the indirect electrooxidation process [24][25][26].…”