Department of Civil and Environmental Engineering, 3-133 Markin/CNRL Natural Resources Engineering Facility, University of Alberta, Edmonton, AB, Canada T6G 2W2.
Sci Total Environ. 2012 Jun 1;426:387-92. doi: 10.1016/j.scitotenv.2012.03.019. Epub 2012 Apr 20.
Naphthenic acids (NAs) are a broad range of alicyclic and aliphatic compounds that are persistent and contribute to the toxicity of oil sands process affected water (OSPW). In this investigation, cyclohexanoic acid (CHA) was selected as a model naphthenic acid, and its oxidation was investigated using advanced oxidation employing a low-pressure ultraviolet light in the presence of hydrogen peroxide (UV/H(2)O(2) process). The effects of two pHs and common OSPW constituents, such as chloride (Cl(-)) and carbonate (CO(3)(2-)) were investigated in ultrapure water. The optimal molar ratio of H(2)O(2) to CHA in the treatment process was also investigated. The pH had no significant effect on the degradation, nor on the formation and degradation of byproducts in ultrapure water. The presence of CO(3)(2-) or Cl(-) significantly decreased the CHA degradation rate. The presence of 700 mg/L CO(3)(2-) or 500 mg/L Cl(-), typical concentrations in OSPW, caused a 55% and 23% decrease in the pseudo-first order degradation rate constants for CHA, respectively. However, no change in byproducts or in the degradation trend of byproducts, in the presence of scavengers was observed. A real OSPW matrix also had a significant impact by decreasing the CHA degradation rate, such that by spiking CHA into the OSPW, the degradation rate decreased up to 82% relative to that in ultrapure water. The results of this study show that UV/H(2)O(2) AOP is capable of degrading CHA as a model NA in ultrapure water. However, in the real applications, the effect of radical scavengers should be taken into consideration for the achievement of best performance of the process.
环烷酸（NAs）是一类广泛存在的脂环族和脂肪族化合物，具有持久性，并导致油砂加工废水（OSPW）具有毒性。在本研究中，环己烷羧酸（CHA）被选为模型环烷酸，并采用低压紫外线在过氧化氢存在下的高级氧化（UV/H2O2 工艺）对其氧化进行了研究。在超纯水中研究了两种 pH 值以及常见的 OSPW 成分，如氯（Cl(-)）和碳酸盐（CO3(2-))的影响。还研究了处理过程中 H2O2 与 CHA 的最佳摩尔比。pH 值对降解、超纯水中副产物的形成和降解均无显著影响。CO3(2-)或 Cl(-)的存在会显著降低 CHA 的降解速率。在 OSPW 中典型浓度为 700mg/L 的 CO3(2-)或 500mg/L 的 Cl(-)，分别导致 CHA 的拟一级降解速率常数降低了 55%和 23%。然而，在存在清除剂的情况下，没有观察到副产物或副产物降解趋势的变化。实际的 OSPW 基质也会产生重大影响，降低 CHA 的降解速率，以至于在向 OSPW 中添加 CHA 时，降解速率相对于在超纯水中降低了 82%。本研究结果表明，UV/H2O2 AOP 能够在超纯水中降解 CHA 作为模型 NA。然而，在实际应用中，为了达到最佳处理效果，应考虑自由基清除剂的影响。
