Institute of Technical Chemistry and Environmental Chemistry, Faculty of Chemistry and Earth Sciences, Friedrich Schiller University Jena, Jena, Germany.
Center for Energy and Environmental Chemistry (CEEC Jena), Faculty of Chemistry and Earth Sciences, Friedrich Schiller University Jena, Jena, Germany.
PLoS One. 2020 Feb 6;15(2):e0228644. doi: 10.1371/journal.pone.0228644. eCollection 2020.
Pyrocatalysis uses thermally excited pyroelectric materials for the generation of reactive oxygen species in water. This unique feature allows it to harvest energy in the form of natural temperature gradients or waste heat from industrial processes in order to degrade organic pollutants at low costs. Its further development into an advanced oxidation process for water remediation is dependent on the availability of pH-robust and nonspecific redox assays for the determination of its oxidation capability. Nevertheless, previous studies neglected the influence of pH changes and they were focused mainly on the degradation of one organic compound or specific chemical dosimetries. In this study, a pH-robust and nonspecific reaction protocol of the dichlorofluorescein assay was established for the investigation of the oxidation capability of the pyrocatalytic process. This reaction protocol was tested on three pyroelectric powders (LiNbO3, LiTaO3, BaTiO3) in different amounts and it overcomes major constraints of a previously used dichlorodihydrofluorescein diacetate-based reaction protocol. Instead of its diacetate, dichlorodihydrofluorescein was used as fluorogenic probe and its concentration was drastically reduced to 1 μM. For the first time, these changes enable the determination and comparison of the oxidation capability independently of pH-rising processes, which are present for all investigated pyroelectric powders up to a pH of 11. Additionally, the precision of the dichlorofluorescein assay was drastically increased and the determination and consideration of autoxidation processes was enabled. Of all three pyroelectric powders, BaTiO3 exhibited the highest oxidation capability with a linear increase with respect to the powder amount.
热释电催化利用热激发的热释电材料在水中产生活性氧物质。这种独特的特性使其能够以自然温度梯度或工业过程废热的形式获取能量，从而以低成本降解有机污染物。它进一步发展成为水修复的高级氧化过程，取决于是否有 pH 稳定且非特异性的氧化还原测定法来确定其氧化能力。然而，以前的研究忽略了 pH 变化的影响，并且主要集中在一种有机化合物或特定化学计量的降解上。在这项研究中，建立了一种 pH 稳定且非特异性的二氯荧光素测定反应方案，用于研究热释电过程的氧化能力。该反应方案在三种不同量的热释电粉末（LiNbO3、LiTaO3、BaTiO3）上进行了测试，克服了以前使用的二氯二氢荧光素二乙酸酯反应方案的主要限制。它使用二氯二氢荧光素而不是二乙酸酯作为荧光探针，其浓度被大幅降低至 1 μM。这些变化首次使氧化能力的测定和比较能够独立于 pH 升高过程进行，对于所有研究的热释电粉末，该过程在 pH 达到 11 之前都是存在的。此外，还大幅提高了二氯荧光素测定法的精密度，并能够进行自氧化过程的测定和考虑。在三种热释电粉末中，BaTiO3 表现出最高的氧化能力，其氧化能力随粉末量呈线性增加。
