Glyphosate and AMPA removal from water by solar induced processes using low Fe( iii ) or Fe( ii ) concentrations

DE ANGELIS, LAURA; DE FRANKENBERG, JOSEFINA; STRIPEIKIS, JORGE D.; SERRA-CLUSELLAS, ANNA; BAVA, MELINA; DI GIOVANNI, NICOLÁS; FIDALGO DE CORTALEZZI, MARÍA M.; BELTRAMO, MERCEDES; VIGLIAROLO, JULIÁN; RENGIFO-HERRERA, JULIÁN A.

Environmental Science: Water Research & Technology

Royal Society of Chemistry

Año: 2019 vol. 5 p. 1932 - 1942

2053-1400

A solar photo-Fenton-like (SPF-like) process is explored for the removal of 1 mg L−1 glyphosate and its main degradation by-product, aminomethylphosphonic acid (AMPA), from Milli-Q water by means of low Fe(III) concentrations (0.6?2 mg L−1) at pH = 2.8 and variable H2O2 concentrations at the laboratory scale. The research is focused on glyphosate and AMPA oxidation, which present similar toxicity patterns. A 1 mg L−1 glyphosate solution requires 5?6 h of the SPF-like process to be degraded when aminute Fe(III) concentration (0.6 mg L−1) is used in acidic water. Glyphosate abatement time is diminished to 2 h when the Fe(III) concentration is increased to 2 mg L−1. At pH levels above 2.8, the herbicide is partially adsorbed onto the colloids of iron oxy(hydroxide) compounds. AMPA requires a higher oxidative power than glyphosate to be degraded, and more than 6 h of solar treatment are needed, using 10 mg L−1 h−1 H2O2 and 2 mg L−1 Fe(III) at acidic pH. Solar photo-Fenton (SPF), using 4 mg L−1 Fe(II) and 10 mg L−1 h−1 H2O2 at pH = 2.8, must be applied to achieve practically total AMPA removal in 6 h of irradiation. SPF-like and SPF treatments led to 70% and 80% mineralization, respectively, under the best operational conditions. This work demonstrates that SPF-like andSPF at low Fe(III) or Fe(II) concentrations are effective treatments for the removal of glyphosate from water at acidic pH. Continuous addition ofH2O2 is required for AMPA abatement.