Degradation of glyphosate in water by the application of surface corona discharges

Abstract

Glyphosate (GLP) is one of the most widely applied herbicides, and is found ubiquitously in the environment. The removal of glyphosate from waste water and soil is challenging and can be achieved with chemical or biological methods, which, nevertheless, suffer from different disadvantages. The application of a physical plasma for the removal of GLP in water was examined by the application of surface corona discharges in a wire-to-cylinder setup filled with argon. The plasma was ignited at the liquid surface without any additives. By applying a photometric method, GLP was detected after derivatisation with fluorenyl methoxycarbonyl chloride, whereas phosphate was determined with ammonium molybdate. A GLP degradation rate of 90.8% could be achieved within a treatment time of 30 minutes with an estimated energy efficiency of 0.32 g/kWh. HIGHLIGHTS Corona discharges ignited at the water surface degraded glyphosate (GLP) more than 90%.; Total carbon mineralisation was indicated by elevated free phosphate concentrations.; Increase of liquid conductivity after plasma treatment implied the formation of ionic degradation products.;

Keywords

• corona discharges
• degradation
• glyphosate
• pesticide
• plasma
• water treatment