The overall objective of the projects is to covalently label humic materials with a radionuclide (e.g. C-14, H-3, I-125) in order to use the labelled material during investigations of their interactions in
(a) complexation reactions with cations (e.g. Eu, Sn, Co, Ni) and cation competition reactions (e.g. with Na, Ca)
(b) sorption of humic and humic complexes onto solid surfaces and
(c) precipitation/dissolution behaviour of humic material.
The radionuclide labelled humic material will provide information on the presence of the complexes radionuclide as well as information on the "free" humic material.
The overall objective of the project is to covalently label humic materials with a radionuclide (eg carbon-14, tritium, iodine-125) in order to use the labelled material during investigations of their interactions in complexation reactions with cations and cation competition reactions, sorption of humic and humic complexes onto solid surfaces and precipitation and dissolution behaviour of humic material. The radionuclidic labelled humic material will provide information on the presence on the complexed radionuclide as well as information on the free humic material.
The preparation of labelled humic material has been approached. Labelling has been carried out using either iodine isotopes or carbon-14. In the case of carbon-14 labellling 2 approaches have been followed primary methylamination of a small fraction of the available carboxylic acid groups in humic acids and secondary enzymatic incorporation rates of the label into the humic materials have been obtained. Thus methylamination gave labelling yield up to approximately 80%, whereas quantitative incorporation of the phenol label was obtained. Preliminary results of the use of these labelled organics, for example in transport studies, have been reported.
The project is subdivided into three phases:
Phase 1: Preparation of labelled humic materials:
a) Preparation of C-14-labelled humic material from C-14-labelled phenol or C-14-labelled methylamine.
b) Preparation of iodine-labelled humic materials.
Phase 2: Characterisation of the labelled humic material:
a) Determination of the acidity, functional group capacity and size distribution of the non-labelled and labelled humic materials.
b) Determination of the europium binding capacity of the non-labelled and labelled humic materials.
Phase 3: Studies on the aqueous and solid surface chemistry of the labelled humic material
a) Investigation and determination of the associating capacities of the labelled humic material with radionuclides of interest (e.g.Ni, Sn, Co).
b) Investigation of solid surface sorption using columns filled with sand.