info:eu-repo/semantics/article
Slow-release formulations of the herbicide picloram by using Fe-Al pillared montmorillonite
Fecha
2017-04Registro en:
Marco Brown, José Luis; Undabeytia, Tomás; Torres Sanchez, Rosa Maria; Dos Santos Afonso, María; Slow-release formulations of the herbicide picloram by using Fe-Al pillared montmorillonite; Springer Heidelberg; Environmental Science and Pollution Research; 24; 11; 4-2017; 10410-10420
0944-1344
1614-7499
CONICET Digital
CONICET
Autor
Marco Brown, José Luis
Undabeytia, Tomás
Torres Sanchez, Rosa Maria
Dos Santos Afonso, María
Resumen
Slow-release formulations of the herbicide picloram (PCM, 4-amino-3,5,6-trichloropyridine-2-carboxylic acid) were designed based on its adsorption on pillared clays (pillared clays (PILCs)) for reducing the water-polluting risk derived from its use in conventional formulations. Fe–Al PILCs were synthesized by the reaction of Na+-montmorillonite (SWy-2) with base-hydrolyzed solutions of Fe and Al. The Fe/(Fe + Al) ratios used were 0.15 and 0.50. The PCM adsorption isotherms on Fe–Al PILCs were well fitted to Langmuir and Freundlich models. The PCM adsorption capacity depended on the Fe content in the PILCs. Slow-release formulations were prepared by enhanced adsorption of the herbicide from PCM-cyclodextrin (CD) complexes in solution. CDs were able to enhance up to 2.5-fold the solubility of PCM by the formation of inclusion complexes where the ring moiety of the herbicide was partially trapped within the CD cavity. Competitive adsorption of anions such as sulfate, phosphate, and chloride as well as the FTIR analysis of PCM-PILC complexes provided evidence of formation of inner sphere complexes of PCM-CD on Fe–Al PILCs. Release of the herbicide in a sandy soil was lower from Fe–Al PILC formulations relative to a PCM commercial formulation.