Electrokinetic and adsorption properties of sepiolite modified by 1-[3-(trimethoxysilyl)propyl]urea
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Surface modification of clay minerals has become increasingly important for improving the practical applications. Modification of sepiolite clay has been performed using 1-[3-(trimethoxysilyl)propyl]urea (TMSPU) in the presence of toluene solution. The utility of the TMSPU-modified sepiolite as an adsorbent for removal of various metal ions from aqueous solutions was investigated. Extensive physicochemical evaluation of the obtained modified sepiolite was conducted using FTIR and XRD techniques, and it was suggested that chemical bonding takes place between the hydroxyl groups and/or oxygen atoms within the structure of sepiolite and methoxy groups of TMSPU. Electrokinetic properties of the formed sepiolite suspensions were also examined by determining their zeta potential. The adsorption capacity of the modified sepiolite for Fe(III), Mn(II), Co(II), Cu(II), Zn(II) and Cd(II) was determined. The effects of pH and temperature on the adsorption process were studied. Toward Fe(III) and Mn(II), the adsorption capacity of the modified sepiolite was high. The adsorption isotherm has been determined and the data have been analysed according to the Langmuir and Freundlich models.