Project Details
Projekt
Compound-specific isotope analysis of aminopolyphosphonate complexing agents to elucidate their sorption and transformation processes in environmental and technical systems
Subject Area
Hydrogeology, Hydrology, Limnology, Urban Water Management, Water Chemistry, Integrated Water Resources Management
Term
since 2021
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 457490294
Aminopolyphosphonates (APPs) are strong metal complexing agents which are increasingly used as complexing agents in industrial and household applications. They are highly water soluble, non-volatile and hardly partition into organic phases. In waste water treatment plants, however, sorption to sewage sludge is considered as the major removal process. Polyphosphonate concentrations in German rivers are currently in the ng L-1 to low µg L-1 range but are predicted to increase due to increased production and usage. Unfortunately, our current ability to assess the environmental fate of aminopolyphosphonates is poor, primarily due to the lack of knowledge about the significance of sorption and degradation processes for the overall removal of APPs in natural and technical systems. Furthermore, reaction mechanisms and pathways are not fully identified, hampering a prediction of the effects of environmental parameters (e.g. pH, cation concentrations, competing ligands) on the fate of APPs. These knowledge gaps hamper the assessment of the environmental fate of APPS as well as the design of treatment strategies for efficient removal of APPs in technical systems. The aim of the proposed research is therefore to identify and characterize sorbents, reactants and environmental conditions that favor the attenuation of APPs in environmental and technical systems. We propose to investigate the effects of crucial environmental parameters (pH, complexing cations, degree of complexation, etc.) on sorption and transformation processes of APPs in carefully designed laboratory experiments. Two major representatives of polyamino-phosphonates, ATMP (amino tris(methylenephosphonic acid) and EDTMP (ethylenediamine-tetra¬(methylenephosphonic acid), will be studied in detail by compound specific isotope analysis in combination with high resolution mass spectrometry and other advanced analytical techniques and experimental procedures to identify and characterize their most significant attenuation processes and mechanisms as well as the major transformation products.The proposed research is divided into three work packages. First we will investigate sorption of APPs at iron (hydr-) oxides, clay minerals and activated carbon/ biochar and quantify the potential isotope fractionation effects due to sorption. Next we will address natural transformation processes of AAPs with a focus on the oxidation by manganese oxides and direct photolysis of APP–Fe(III) complexes. Finally, AAP degradation processes in technical systems such as ozonolysis and electrochemical oxidation will be investigated.
DFG Programme
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