@article{DemetriouPashalidisNicolaidesetal.2013,
  author    = {Demetriou, Antri and Pashalidis, Ioannis and Nicolaides, Athanassios V. and Kumke, Michael Uwe},
  title     = {Surface mechanism of the boron adsorption on alumina in aqueous solutions},
  series = {Desalination and water treatment : science and engineering},
  volume    = {51},
  journal   = {Desalination and water treatment : science and engineering},
  number    = {31-33},
  publisher = {Taylor \& Francis Group},
  address   = {Philadelphia},
  issn      = {1944-3994},
  doi       = {10.1080/19443994.2013.764354},
  pages     = {6130 -- 6136},
  year      = {2013},
  abstract  = {The adsorption of boron (boric acid) from aqueous solutions on alumina has been investigated at pH 8.0, I=0.1M NaClO4, T=22 +/- 3 degrees C, and under normal atmospheric conditions. The characterization of the adsorbed species was performed by Raman spectroscopy and the spectroscopic speciation was assisted by theoretical DFT calculations. Evaluation of the spectroscopic data points to the formation of inner-sphere surface complexes and indicates the formation of two different types of adsorbed boron species. The theoretical calculations corroborate the spectroscopic data and indicate that at low boron concentration the monodentate surface species dominates, whereas increased boron concentration favors the formation of a bidentate surface species. Assuming low coverage, the conditional formation constant for the monodentate surface species has been evaluated to be log=4.1 +/- 0.1.},
  language  = {en}
}
@article{AntoniouPashalidisGessneretal.2011,
  author    = {Antoniou, Stella and Pashalidis, Ioannis and Gessner, Andre and Kumke, Michael Uwe},
  title     = {Spectroscopic investigations on the effect of humic acid on the formation and solubility of secondary solid phases of Ln(2)(CO3)(3)},
  series = {Journal of rare earths},
  volume    = {29},
  journal   = {Journal of rare earths},
  number    = {6},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {1002-0721},
  doi       = {10.1016/S1002-0721(10)60490-5},
  pages     = {516 -- 521},
  year      = {2011},
  abstract  = {The formation of secondary Ln(III) solid phases (e.g., Nd-2(CO3)(3) and Sm-2(CO3)(3)) was studied as a function of the humic acid concentration in 0.1 mol/L NaClO4 aqueous solution in the neutral pH range (5-6.5). The solid phases under investigation were prepared by alkaline precipitation under 100\% CO2 atmosphere and characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD), time-resolved laser fluorescence spectroscopy (TRLFS), diffuse reflectance ultraviolet-visible (DR-UV-Vis), Raman spectroscopy, and solubility measurements. The spectroscopic data obtained indicated that Nd-2(CO3)(3) and Sm-2(CO3)(3) were stable and remained the solubility limiting solid phases even in the presence of increased humic acid concentration (0.5 g/L) in solution. Upon base addition in the Ln(III)-HA system, decomplexation of the previously formed Ln(III)-humate complexes and precipitation of two distinct phases occurred, the inorganic (Ln(2)(CO3)(3)) and the organic phase (HA), which was adsorbed on the particle surface of the former. Nevertheless, humic acid affected the particle size of the solid phases. Increasing humic acid concentration resulted in decreasing crystallite size of the Nd-2(CO3)(3) and increasing crystallite size of the Sm-2(CO3)(3) solid phase, and affected inversely the solubility of the solid phases. However, this impact on the solid phase properties was expected to be of minor relevance regarding the chemical behavior and migration of trivalent lanthanides and actinides in the geosphere.},
  language  = {en}
}