Removal of organophosphorus pesticides in water with supported silica Fe3O4 magnetic nanoparticles

This paper evaluates the efficiency of Fe3O4 magnetic nanoparticles embedded in silica matrix, by a sol-gel method, as adsorbent of two organophosphate pesticides, Chlorfenvifos (Chlorf) and Chlorpyrifos (Chlorp), in sewage. The Fe3O4-SiO2 Nps have an average size of 5 nm. The detection limits were 1 μ g L-1 for the Chlorf and 2 μ g L-1 for the Chlorp, obtaining an intra-day precision of 2% and inter-day 3%. According to the Langmuir adsorption isotherm, the Chlorp was identified as the more adsorbed species with Smax = de 0.70 ± 0.15 μg g-1, while Smax = 0.40 ± 0.12 μg g-1 for Chlorf. The procedure was tested on sewage, reaching analyte's removal between 60-85%. The adsorption mechanism of pesticides is attributed to the hydrophobic interaction between these compounds and aliphatic chains of CTAB micelles, since the percentage of compounds in the liquid was less than 10%. © 2014, Universidad Central de Venezuela. All rights reserved.