TY - GEN A1 - Kuhn, Ramona A1 - Jensch, Robert A1 - Bryant, Isaac Mbir A1 - Fischer, Thomas A1 - Liebsch, Stephan A1 - Martienssen, Marion T1 - The influence of selected bivalent metal ions on the photolysis of diethylenetriamine penta(methylenephosphonic acid) T2 - Chemosphere N2 - 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. KW - DTPMP KW - Ferrous ion KW - LC/MS KW - Phosphonates KW - Photolysis Y1 - 2018 U6 - https://doi.org/10.1016/j.chemosphere.2018.07.033 SN - 0045-6535 IS - 210 SP - 726 EP - 733 ER - TY - GEN A1 - Kuhn, Ramona A1 - Bryant, Isaac Mbir A1 - Jensch, Robert A1 - Liebsch, Stephan A1 - Martienssen, Marion T1 - Photolysis of hexamethylenediaminetetra(methylenephosphonic acid) (HDTMP) using manganese and hydrogen peroxide T2 - Emerging Contaminants N2 - 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 KW - HDTMP KW - Hydrogen peroxide KW - Manganese KW - LC/MS KW - Phosphonates KW - Photolysis Y1 - 2019 U6 - https://doi.org/10.1016/j.emcon.2019.11.003 N1 - Die präsentierten Ergebnissen in diesem Artikel sind im Rahmen von zwei Abschlussarbeiten an der BTU erstellt worden. VL - 2020 IS - 6 SP - 10 EP - 19 ER -