Determination of the adsorption process of tributyltin (TBT) and monobutyltin (MBT) onto kaolinite surface using Fourier transform infrared (FTIR) spectroscopy

Depending on the molecular structure of the butyltin compounds, different surface complexes were found. According to our results, TBT occurring with trigonal-bipyramidal molecule structure are bonded by the formation of a mononuclear complex having monodentate configuration. In this case, one oxygen atom of a Al(Si)O lattice group is directly bonded to the Sn atom of a TBT molecule. The adsorption of TBT molecules showing a tetrahedral configuration results from hydrogen bonding. MBT forms octahedral units in aqueous solution and the molecule is bonded to the kaolinite surface by reaction with the “outer hydrogen” groups of the clay minerals.