Preliminary studies in removing atrazine, isoproturon and imidacloprid from water by natural sepiolite

Sepiolite is a hydrated magnesium silicate clay with a fibrous structure and binder properties. To calculate the potential use of sepiolite in removing atrazine [2-chloro-4-ethylamino-6-isopropilamino-1,3,5,-triazine], isoproturon [3-(4-isopropylphenyl)-1,1-dimethylurea] and imidacloprid [1-(6-chloro-3-pyridinylmethyl)-N-nitroimidazolin-2-ylideneamine] from water, the adsorption of atrazine, isoproturon and imidacloprid on sepiolite desiccated at 110 °C from aqueous solution at 25 °C has been studied by using batch experiments. In addition, column experiments were carried out with the sepiolite sample using aqueous solutions of atrazine, isoproturon and imidacloprid at a concentration of 20.0 × 10−4 cmol dm−3. The experimental data points have been fitted to the Langmuir equation to calculate the adsorption capacities (Xm). Values for Xm ranged from 2.70 × 10−1 cmol kg−1 for isoproturon up to 3.97 × 10−1 cmol kg−1 for atrazine. The removal efficiency (R) ranged from 36.7% for isoproturon up to 74.3% for atrazine. The batch experiments show that the sepiolite is more effective in adsorbing atrazine than imidacloprid and isoproturon. The column experiments show that sepiolite might be reasonably used in removing atrazine, the column efficiency being 46%. The data indicate that a readily available and inexpensive Spanish sepiolite can be employed as a filter for contaminated waters with these pesticides, controlling their release to the environment.