Fe-pillared Clay adsorption of picloram herbicide

J.L.M. BROWN; C.M. BARBOSA; R.M. TORRES SANCHEZ; M. DOS SANTOS AFONSO; R. MERCADER,

APPLIED CLAY SCIENCE

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2012 vol. 58 p. 25 - 33

0169-1317

The adsorption of picloram on Fe Oxide Pillared Clays (PILC) as a possible basis for the development of adsorbentmaterials for the remediation of polluted environments was studied. To this end, after characterizingPILC obtained from raw clay from Wyoming, USA by XRD, elemental analysis, Mössbauer spectroscopy,DTA, TGA and N2 adsorption (BET), the picloram adsorption was studied at constant pH and ionic strengthafter 48 h equilibration with an aqueous solution of PCM. PCM adsorbed samples were characterized bySEM, zeta-potential vs pH functions, FTIR and TGA-DTA and the adsorption was modellated using Langmuirand Freundlich models.The results reveal that the surface area and interlayer space of PILC are bigger than those of raw montmorillonite.An analysis of the adsorption isotherms of picloram on the PILC showed that picloram adsorptionincreases with decreasing pH. The adsorption of PCM on PILC was 150 times higher than that found forraw montmorillonite under similar conditions. The zeta-potential vs pH functions shape and FTIR indicatedthat PCM coordinates the surface iron centers throughout pyridinic nitrogen atom forming inner-spherecomplexes. The much greater PCM adsorption on PILC turns the process into an excellent candidate tobe used for dosing or remediation of pesticides.