Institute of Municipal and Environmental Engineering, College of Civil Engineering, Huaqiao University, Xiamen, Fujian, 361021, PR China.
Institute of Municipal and Environmental Engineering, College of Civil Engineering, Huaqiao University, Xiamen, Fujian, 361021, PR China; State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin, Heilongjiang, 150090, PR China.
Chemosphere. 2021 Jun;272:128577. doi: 10.1016/j.chemosphere.2020.128577. Epub 2020 Oct 8.
In this study, iodometric spectrophotometry, the most-used method for detecting peroxydisulfate (PDS), was modified by increasing the concentration of potassium iodide (KI) for realizing the immediate PDS determination and avoiding the interference of hydroxylamine. Kinetic studies showed that the reaction between PDS and I to generate the yellow-colored I followed the kinetic equation as [Formula: see text] . Detection time of the iodometric spectrophotometry was shortened from 15 min to 15 s when KI concentration was increased from 0.6 M to 4.8 M. Different with the previous iodometric spectrophotometry, the modified method using 4.8 M KI as the indicator was well tolerable to the interference of hydroxylamine at acidic pH conditions. The calibration curve of the modified method showed a well linear relationship (R = 0.999) between the absorbance of I at 352 nm and PDS concentration in the range of 0-80 μM. The modified method was highly sensitive with the absorptivity of 2.5 × 10 M cm and the limit of detection of 0.11 μM. Moreover, the modified method was successfully applied for monitoring the change of PDS concentration during the degradation of diclofenac with four different PDS-based AOPs, the calculated reaction stoichiometric efficiency (RSE(%)=DiclofenacdegradedPDSconsumed×100%) followed the order as heat/PDS system > hydroxylamine/Fe/PDS system > hydroxylamine/Cu/PDS system > Fe/PDS system.
在这项研究中，过二硫酸盐（PDS）最常用的检测方法——碘量分光光度法，通过增加碘化钾（KI）的浓度进行了改进，以实现即时的 PDS 测定并避免羟胺的干扰。动力学研究表明，PDS 与 I 之间的反应生成黄色的 I 遵循动力学方程 [公式：见文本]。当 KI 浓度从 0.6 M 增加到 4.8 M 时，碘量分光光度法的检测时间从 15 分钟缩短到 15 秒。与以前的碘量分光光度法不同，使用 4.8 M KI 作为指示剂的改进方法在酸性 pH 条件下对羟胺的干扰具有良好的耐受性。改进方法的校准曲线显示，在 0-80 μM 的范围内，I 在 352nm 处的吸光度与 PDS 浓度之间呈良好的线性关系（R = 0.999）。改进方法具有较高的灵敏度，吸光度为 2.5×10 M cm，检测限为 0.11 μM。此外，该改进方法成功应用于监测四种不同的基于 PDS 的 AOPs 降解过程中 PDS 浓度的变化，计算得到的反应计量效率（RSE（%）=降解的 Diclofenac PDS 消耗×100%）的顺序为：热/PDS 系统>羟胺/Fe/PDS 系统>羟胺/Cu/PDS 系统>Fe/PDS 系统。
