Title : 
  Normalized FT - IR spectra of crystalline and amorphous Fe- Al - hydroxides during P adsorption 
 Abstract_text_1 : 
  Normalized FT - IR spectra of crystalline and amorphous Fe- Al - hydroxides during P adsorption . 
 Abstract_text_2 : 
  Fourier - Transform Infrared ( FT - IR ) spectroscopic analyses were carried out during P adsorption on highly crystalline gibbsite , poorly crystalline 2 - line - ferrihydrite and amorphous Fe : Al - hydroxide mixtures in the molar ratio 1:0 , 10:1 , 1:1 , 1:10 and 0:1 . The elemental composition of the adsorbents was verified by using SEM - EDX , scanning electron microscopy ( DSM 962 , Zeiss , Oberkochen , Germany ) with energy dispersive X - ray spectroscopy ( X - Max 50 mm² with INCA , Oxford Instruments , Abingdon , Great Britain ) . The formation of pure Al(OH)3 and FeO(OH ) for the amorphous hydroxides was revealed . Determination of the adsorbent crystallization as well as amorphous structures was carried out by X - ray diffraction ( XRD ) using a PANalytical Empyrean powder diffractometer ( Almelo , Netherlands ) from GFZ Potsdam , with a theta - theta - goniometer , Cu - Kα radiation ( λ=0.15418 nm ) , automatic divergent and anti - scatter slits and a PIXcel3D detector . Diffraction data were recorded from 4.6 ° to 84.9 ° 2ϴ with a step - size of 0.0131 and a step time of 58.4 s. The generator settings were 40 kV and 40 mA. Specific surface areas of all adsorbents were determined with an Autosorb-1 ( Quantachrome , Odelzhausen , Germany ) using a multi - point BET - measurement ( Brunauer - Emmett - Teller ) and N2 as adsorptive medium . P adsorption was investigated with batch experiments , in which a solid - solution ratio of 1:20 was chosen for gibbsite , and a solid - solution ratio of 1:200 was chosen for ferrihydrite and the Fe : Al - hydroxide mixtures due to their high specific surface areas and P - adsorption capacity . The initial P - concentrations for the adsorption experiments were 150 µmol l-1 , 1000 µmol l-1 and 2000 µmol l-1 KH2PO4 for gibbsite and 1000 µmol l-1 , 2000 µmol l-1 and 5000 µmol l-1 KH2PO4 for ferrihydrite and the Fe : Al - hydroxides with a 0.01 mol l-1 CaCl2 - background electrolyte solution , adjusted to a pH of 6 . For P measurements , the gibbsite and ferrihydrite samples were centrifuged for 15 min at 336 × G , while the Fe : Al - hydroxide samples were centrifuged for 15 min at 21572 × G. The clear supernatant was filtered by using P - poor Whatman 512 1/1 filters . For FT - IR spectroscopic measurements , the remaining solid matter was dried for 24 h at 40 ° C , stored overnight in a desiccator and analyzed without further treatment . IR spectroscopic measurements were carried out by measurement of the absorbance in the FT - IR DRIFT mode ( Tensor 27 HTS - XT , Bruker , Billerica , USA ) with 40 scans per sample , a wavenumber range from 4000 to 400 cm-1 , and a resolution of 1.9 cm-1 . Research domain : Plant Nutrition Research question : Which P bindings are formed on the various mineral Fe- and Al - hydroxide surfaces and how do inorganic and organic compounds contribute to the availability of both adsorbed / precipitated and naturally bound phosphorus from phosphate minerals ? 
 Keywords : 
  Soil , Phosphate fertilizers , fertilizers , farm inputs , Phosphates , Bones , Laboratory experimentation , Fe- Al - Hydroxide , Phosphorus , Adsorption , FT - IR spectrsocopy , Gibbsite , Ferrihydrite , opendata , Boden , Phosphorus , Adsorption , Spectroscopy