Zhang Ying, Chelme-Ayala Pamela, Klamerth Nikolaus, Gamal El-Din Mohamed
Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada.
Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada.
Chemosphere. 2017 Jul;179:359-366. doi: 10.1016/j.chemosphere.2017.03.112. Epub 2017 Mar 28.
Naphthenic acids (NAs) are a highly complex mixture of organic compounds naturally present in bitumen and identified as the primary toxic constituent of oil sands process-affected water (OSPW). This work investigated the degradation of cyclohexanoic acid (CHA), a model NA compound, and natural occurring NAs during the UV photolysis of Fe(III)-nitrilotriacetic acid (UV-Fe(III)NTA) and UV-NTA-Fenton processes. The results indicated that in the UV-Fe(III)NTA process at pH 8, the CHA removal increased with increasing NTA dose (0.18, 0.36 and 0.72 mM), while it was independent of the Fe(III) dose (0.09, 0.18 and 0.36 mM). Moreover, the three Fe concentrations had no influence on the photolysis of the Fe(III)NTA complex. The main responsible species for the CHA degradation was hydroxyl radical (OH), and the role of dissolved O in the OH generation was found to be negligible. Real OSPW was treated with the UV-Fe(III)NTA and UV-NTA-Fenton advanced oxidation processes (AOPs). The removals of classical NAs (O-NAs), oxidized NAs with one additional oxygen atom (O-NAs) and with two additional oxygen atoms (O-NAs) were 44.5%, 21.3%, and 25.2% in the UV-Fe(III)NTA process, respectively, and 98.4%, 86.0%, and 81.0% in the UV-NTA-Fenton process, respectively. There was no influence of O on the NA removal in these two processes. The results also confirmed the high reactivity of the O-NA species with more carbons and increasing number of rings or double bond equivalents. This work opens a new window for the possible treatment of OSPW at natural pH using these AOPs.
环烷酸（NAs）是天然存在于沥青中的一种高度复杂的有机化合物混合物，被确定为油砂加工受影响水（OSPW）的主要有毒成分。本研究考察了模型NA化合物环己酸（CHA）以及天然存在的NAs在Fe(III)-次氮基三乙酸紫外光解（UV-Fe(III)NTA）和UV-NTA-芬顿过程中的降解情况。结果表明，在pH为8的UV-Fe(III)NTA过程中，CHA的去除率随NTA剂量（0.18、0.36和0.72 mM）的增加而增加，而与Fe(III)剂量（0.09、0.18和0.36 mM）无关。此外，三种Fe浓度对Fe(III)NTA络合物的光解没有影响。CHA降解的主要活性物种是羟基自由基（OH），发现溶解氧在OH生成中的作用可忽略不计。采用UV-Fe(III)NTA和UV-NTA-芬顿高级氧化工艺（AOPs）处理实际的OSPW。在UV-Fe(III)NTA过程中，经典NAs（O-NAs）、含一个额外氧原子的氧化NAs（O-NAs）和含两个额外氧原子的氧化NAs（O-NAs）的去除率分别为44.5%、21.3%和25.2%，在UV-NTA-芬顿过程中分别为98.4%、86.0%和81.0%。在这两个过程中，溶解氧对NAs去除没有影响。结果还证实了含碳量更多、环数或双键当量增加的O-NA物种具有较高的反应活性。这项工作为使用这些AOPs在自然pH值下处理OSPW开辟了新的途径。
