Adsorption of linuron by an Algerian palygorskite modified with magnetic iron

Abstract Three types of palygorskite nanoparticles for the retention of the herbicide linuron in water were tested: purified palygorskite (Pur Pal), palygorskite modified by magnetic iron oxides (FeO Pal 1 ) and this one synthesized by hydrothermal treatment (FeO Pal 2 ). The adsorbents were characterized by X-ray diffraction (XRD), infrared spectroscopy (FTIR), electron microscopy (TEM) and chemical analysis (XRF). XRD patterns indicate the presence of a magnetic Fe 2 O 3 compound, and TEM images evidence how these crystals cover the palygorskite fibers' surface with different crystallite sizes (7–15 nm in FeO Pal 1 and 30-50 nm in FeO Pal 2 ). The adsorbent mass, the contact time, the initial adsorbate concentration and the effect of temperature were evaluated for linuron retention. Adsorption kinetics revealed that adsorption followed a pseudo-second order equation. Adsorption isotherms were better fitted to the Freundlich than to the Langmuir equation. Removed linuron amounts were ranged as FeO Pal 2 (83%) > FeO Pal 1 (55%) > Pur Pal (27%). The adsorbents could be used as a cheap alternative for pesticide removal in environmentally-contaminated waters.