@misc{KuhnJenschBryantetal., author = {Kuhn, Ramona and Jensch, Robert and Bryant, Isaac Mbir and Fischer, Thomas and Liebsch, Stephan and Martienssen, Marion}, title = {The influence of selected bivalent metal ions on the photolysis of diethylenetriamine penta(methylenephosphonic acid)}, series = {Chemosphere}, journal = {Chemosphere}, number = {210}, issn = {0045-6535}, doi = {10.1016/j.chemosphere.2018.07.033}, pages = {726 -- 733}, abstract = {DTPMP is predominantly utilized as scale inhibitor. We investigated the reaction rates and degradation mechanism of DTPMP with and without addition of Fe²⁺, Mg²⁺ and Ca²⁺ by performing LC/MS and ³¹P-NMR analyses. DTPMP undergoes conversion with and without addition of bivalent metal ions. The initial cleavage of DTPMP is initiated at the C-N bond leading to release of IDMP as its major breakdown product. The release of smaller quantities of EABMP and AMPA confirmed the nucleophilic attack on the DTPMP amines. Oxidation of Fe²⁺ to Fe³⁺ during the initial 30 min indicated an intramolecular electron transfer changing the electron density distribution at the nitrogen centre, which increased the radical attack during UV irradiation. Independent of the fact that Fe acted as catalyst and Mg²⁺ and Ca²⁺ acted as reactants, we found no significant differences in their degradation mechanisms. However, the reaction rates were strongly affected by the addition of the bivalent metal ions as Fe²⁺ accelerated most DTPMP degradation followed by Mg²⁺ and Ca²⁺. The UV treatment without metal ion addition was four times slower compared with Fe²⁺ addition. We conclude that in environments rich in ferrous iron and/or at reduced redox potential, photolysis of DTPMP will be catalysed by iron and will lead to accumulation of IDMP, EABMP and AMPA and several other none-quantifiable breakdown products.}, language = {en} } @misc{KuhnJenschBryantetal., author = {Kuhn, Ramona and Jensch, Robert and Bryant, Isaac Mbir and Fischer, Thomas and Liebsch, Stephan and Martienssen, Marion}, title = {Rapid sample clean-up procedure for aminophosphonate determination by LC/MS analysis}, series = {Talanta}, volume = {208}, journal = {Talanta}, issn = {0039-9140}, doi = {10.1016/j.talanta.2019.120454}, pages = {6}, abstract = {Aminophosphonates are commonly utilised for complexing bivalent ions such as calcium and magnesium. With regard to environmental samples, the analysis of these highly polar compounds is still challenging due to matrix effects and lacking analytical standard methods. We have recently developed a LC/MS method for common aminophosphonates without derivatisation. This LC/MS method delivers precise and accurate measurement for standard samples with very low concentration of cations disturbing the analysis. However, due to matrix effects this LC/MS method requires a sample clean-up being also applicable to natural water or wastewater samples. We developed and optimised a sample clean-up procedure applying strong cation exchange resin Dowex 50WX8. This clean-up allows a single LC/MS analysis of hydroxyethelidene(diphosphonic acid) (HEDP), aminotris(methylenephosphonic acid) (ATMP), ethylenediaminetetra(methyloenephosphonic acid) (EDTMP), diethylenetriaminepenta(methylenephosphonic acid) (DTPMP) and its major intermediates amino(methylphosphonic acid) (AMPA) and iminodi(methylenephosphonic acid) (IDMP). We compared different test conditions with six aminophosphonates in either ultra pure water or tap water. The latter was used to simulate cation concentrations typical for natural waters. To elute all aminophosphonate including AMPA, ammonium acetate addition was necessary. The addition of ammonium acetate was combinable with all tested aminophosphonates and provides high sample quality for LC/MS analysis. For acceptable recovery, the smallest aminophosphonate AMPA required the highest addition of ammonium acetate (1000 mg L-1) during the sample clean-up. Finally, the optimised clean-up procedure was successfully applied to identify and quantify phosphonates from an industrial wastewater sample. The sample clean-up procedure is simple, cheap, rapid and precise and can be further combined with solid phase extraction and more sensitive LC/MS methods.}, language = {en} } @misc{KuhnJenschBryantetal., author = {Kuhn, Ramona and Jensch, Robert and Bryant, Isaac Mbir and Fischer, Thomas and Liebsch, Stephan and Martienssen, Marion}, title = {Photodegradation of ethylenediaminetetra(methylenephosphonic acid) - The effect of the system configuration}, series = {Journal of Photochemistry \& Photobiology A: Chemistry}, volume = {388}, journal = {Journal of Photochemistry \& Photobiology A: Chemistry}, issn = {1010-6030}, doi = {10.1016/j.jphotochem.2019.112192}, pages = {9}, abstract = {Photodegradation of aminophosphonates such as ethylenediaminetetra(methylenephosphonic acid) (EDTMP) is recently assumed being the major degradation pathway in aquatic environments. Several photolysis studies were reported about EDTMP and possible breakdown products occurring in natural ecosystems. Reliable prediction of environmental photolysis of parent compounds and possible release of breakdown products requires different set-up conditions and varying the parameters influencing the photodegradation. We studied the influence of three different system configurations during UV degradation of EDTMP. These three configurations differed either in geometry and/or treated sample volumes. System 1 was equipped with a direct cooling jacket at the UV lamp. System 2 had the geometry of system 1 but there was no usage of a direct cooling jacket. System 3 was a gas-tight system with a larger sample volume. Using the chemical actinometer potassium ferrioxalate, we determined the highest photon flux for system 3 followed by system 2 and 1. In addition, we performed scavenger experiments with methanol and ascorbic acid in order to prove the dominating radical species. In system 1, the addition of methanol showed almost no effect while the ascorbic acid resulted in a reduction of 57.1\% orthophosphate released. Therefore we conclude that in system 1 the radical-drive degradation of EDTMP is mainly based on superoxide radicals. In system 2 and 3 both radical species, i.e., hydroxyl radicals and superoxide radicals, contribute to the photodegradation of EDTMP. We determined different half-lives for EDTMP for the three different systems configurations. For system 1, the estimated half-life achieved was 14.09 ± 0.15 min. For system 2 and 3, the half-lives were almost similar and averaged 4.75 ± 0.05 min and 5.02 ± 0.20 min, respectively. Contrary to our assumption to also find the highest degradation rate for system 3, we found the highest degradation rate for system configuration 2 as a result of the differences in the construction and geometry of the three systems. Our findings lead us to recommend the three system configuration for different research purposes. Thus, we recommend system 1 for detailed studies on the degradation pathway of the parent compound and their breakdown products. System 2 is recommended as a suitable configuration for kinetic studies of the parent compound. And finally, we recommend the system configuration 3 for complete mass balances. The gas-tight system allows determining all soluble and gaseous compounds.}, language = {en} } @misc{KuhnBryantJenschetal., author = {Kuhn, Ramona and Bryant, Isaac Mbir and Jensch, Robert and Liebsch, Stephan and Martienssen, Marion}, title = {Photolysis of hexamethylenediaminetetra(methylenephosphonic acid) (HDTMP) using manganese and hydrogen peroxide}, series = {Emerging Contaminants}, volume = {2020}, journal = {Emerging Contaminants}, number = {6}, doi = {10.1016/j.emcon.2019.11.003}, pages = {10 -- 19}, abstract = {Aminophosphonates such as hexamethylenediaminetreta(methylene phosphonic acid) (HDTMP) are categorised as persistent substances. They are commonly used as scale inhibitors in cooling water systems and desalination processes. After utilisation, they are often discharged into aquatic environment without pre-treatment. Advanced oxidation processes (AOP) are promising pre-treatments for industrial wastewater treatments. We investigated the photodegradation of HDTMP with or without addition of manganese (Mn2þ) and/or H2O2. Similar to results of our former photodegradation studies, we found that HDTMP also undergoes conversion with or without additives during the ultra violet (UV) irradiation. The reaction rate was most affected by the addition of H2O2, i.e. the HDTMP degradation was accelerated by a factor 3.85 compared with UV treatment without additives. The addition of Mn2þ accelerated the degradation of HDTMP only by a factor 1.53 compared with the UV treatment without additives. The combined addition of Mn2þ and H2O2 accelerated the HDTMP degradation by a factor 2.81. Interestingly, the initial cleavage is not initiated as expected at the CeN bond but at the CeP bond of the methyl carbon and the phosphorus of the methylenephosphonic acid group of HDTMP. This initial cleavage was independent whether the UV treatment was performed with or without additives. Therefore, we conclude that the degradation mechanism is similar independent of the four tested treatment conditions. We identified amino(methylenephosphonic acid) AMPA, dimethylamino(methylenephosphonic acid) DAMP and iminodi(methylenephosphonic acid) IDMP as the major breakdown products by performing LC/MS analyses. The major mineralisation products were ortho-phosphate, ammonium and carbon dioxide. The mass balances of unknown breakdown products}, language = {en} }