Interaction between glycine and Na-, Ca- and Cu-rich smectites

The interactions between glycine and two Na-, Ca- and Cu-exchanged smectite s with different layer-charge location were studied. The sorption of glycin e depends on the nature of the interlayer cations (Ca < Na < Cu), and on th e type of smectite. Sequential extraction procedures were carried out in or der to test the possibility of removing metals and/or glycine from the smec tite interlayer. By the end of the treatments, the release of the amino aci d from the substrates, with the exception of Cu-rich smectite, was virtuall y complete. The thermal curves of glycine-smectites confirm the stronger bo nding of the amino acid with Cu-exchanged samples, and FTIR spectra indicat e that glycine is mainly sorbed in the zwittterionic form. The data obtaine d suggest that in investigations into mechanisms of the binding of metals b y minerals and their subsequent mobilization, amino acids merit close atten tion.