Faculty of Geosciences and Environmental Engineering, Southwest Jiaotong University, Chengdu, 611756, China.
Environ Sci Pollut Res Int. 2020 Feb;27(6):6042-6051. doi: 10.1007/s11356-019-07367-1. Epub 2019 Dec 21.
In this study, refractory organic compounds from dinitrodiazophenol (DDNP) containing industrial wastewater were degraded through two ultraviolet (UV)-based advanced oxidation processes: UV/hydrogen peroxide (UV/HO) and UV/potassium persulfate (UV/PS) processes. In both processes, the synergistic effects, operational parameters (i.e., oxidant dosage and initial pH value), and pseudo first-order constant k were systematically studied. Moreover, the reactive oxygen species formed in the UV/HO and UV/PS processes were identified, and the degradation of refractory organic compounds was characterized through UV-visible spectra analysis. The improvement in biodegradability of DDNP industrial wastewater after treatment by different processes was compared. Both the UV/HO (synergistic coefficient F = 61.34) and UV/PS (synergistic coefficient F = 54.85) processes showed significant, highly synergistic effects. The increase in oxidant dosage was beneficial in organic compound removal in both the UV/HO and UV/PS processes, but excessive HO showed a stronger inhibition of the increase in organic compound removal than that in the UV/PS process. In addition, an acidic environment was more conducive to organic compound degradation in the UV/HO process, whereas the initial pH value had less of an influence on the UV/PS process. Under optimal conditions for the UV/HO and UV/PS processes, the CN and COD removal efficiencies were 99.71%, 66.35%, 99.69%, and 70.81%, respectively, and the k values for COD removal were 0.0804 and 0.0824 min. Tests to identify reactive oxygen species showed that the hydroxyl radical was the predominant oxidizing species in the UV/HO process, whereas the hydroxyl and sulfate radicals were both identified in the UV/PS process, and the sulfate radical contributed the most to the degradation of organic compounds. In addition, spectrum analysis revealed that the complex structure (e.g., benzene ring, nitro group, and diazo group) of refractory organic compounds from DDNP industrial wastewater was effectively destroyed by the UV/HO and UV/PS processes, and both processes improved the biodegradability (biochemical oxygen demand for 5 days/chemical oxygen demand (BOD/COD)) of DDNP industrial wastewater from 0.052 to 0.665 and 0.717, respectively. Overall, both the UV/HO and UV/PS processes effectively degraded the refractory organic compounds from DDNP industrial wastewater, and the UV/PS process exhibited a higher organic compound removal efficiency and better applicability.
在这项研究中，通过两种基于紫外线（UV）的高级氧化工艺：UV/过氧化氢（UV/HO）和 UV/过硫酸钾（UV/PS）工艺，降解了含有二硝酚（DDNP）的工业废水中的难降解有机物。在这两种工艺中，系统研究了协同作用、操作参数（即氧化剂用量和初始 pH 值）和伪一级常数 k。此外，还鉴定了在 UV/HO 和 UV/PS 工艺中形成的活性氧物种，并通过紫外-可见光谱分析对难降解有机物的降解进行了表征。比较了不同工艺处理后 DDNP 工业废水的可生物降解性的提高。UV/HO（协同系数 F=61.34）和 UV/PS（协同系数 F=54.85）工艺均表现出显著的、高度协同的效果。增加氧化剂用量有利于两种 UV/HO 和 UV/PS 工艺中有机物的去除，但过量的 HO 对有机物去除增加的抑制作用强于 UV/PS 工艺。此外，在酸性环境中更有利于 UV/HO 工艺中有机物的降解，而初始 pH 值对 UV/PS 工艺的影响较小。在 UV/HO 和 UV/PS 工艺的最佳条件下，CN 和 COD 的去除效率分别为 99.71%、66.35%、99.69%和 70.81%，COD 去除的 k 值分别为 0.0804 和 0.0824 min。鉴定活性氧物种的试验表明，在 UV/HO 工艺中，羟基自由基是主要的氧化剂，而在 UV/PS 工艺中则同时鉴定出了羟基自由基和硫酸根自由基，硫酸根自由基对有机物的降解贡献最大。此外，光谱分析表明，UV/HO 和 UV/PS 工艺有效破坏了 DDNP 工业废水中难降解有机物的复杂结构（如苯环、硝基和重氮基），两种工艺均提高了 DDNP 工业废水的可生化性（BOD/COD 为 5 天/化学需氧量（BOD/COD）），分别为 0.052 至 0.665 和 0.717。总体而言，UV/HO 和 UV/PS 工艺均能有效降解 DDNP 工业废水中的难降解有机物，UV/PS 工艺具有更高的有机物去除效率和更好的适用性。
