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 CN 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 Fe²⁺ 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.

DTPMP主要用作阻垢剂。我们通过进行LC / MS和³¹ P NMR分析研究了添加和不添加Fe 2 ⁺，Mg ²⁺和Ca ²⁺的DTPMP的反应速率和降解机理。在添加和不添加二价金属离子的情况下，DTPMP都会进行转化。DTPMP的初始切割始于C N键，导致IDMP释放为其主要分解产物。少量EABMP和AMPA的释放证实了对DTPMP胺的亲核攻击。Fe ²⁺氧化为Fe ³⁺在最初的30分钟内，表明分子内的电子转移改变了氮中心的电子密度分布，这增加了UV辐射期间的自由基攻击。独立于Fe ²⁺充当催化剂，Mg ²⁺和Ca ²⁺充当反应物这一事实，我们发现它们的降解机理没有显着差异。然而，由于Fe ²⁺加速了大多数DTPMP的降解，随后是Mg ²⁺和Ca ²⁺，因此添加二价金属离子对反应速率有很大的影响。不添加金属离子的紫外线处理比Fe ²⁺慢四倍添加。我们得出的结论是，在富含亚铁和/或氧化还原电位降低的环境中，DTPMP的光解将被铁催化，并导致IDMP，EABMP和AMPA以及其他几种不可量化的分解产物积聚。