Oxidation of Oil Sands Process-Affected Water by Potassium Ferrate(VI)

Abstract

This paper investigates the oxidation of oil sands process-affected water (OSPW) by potassium ferrate(VI). Due to the selectivity of ferrate(VI) oxidation, two-ring and three-ring fluorescing aromatics were preferentially removed at doses <100 mg/L Fe(VI), and one-ring aromatics were removed only at doses ≥100 mg/L Fe(VI). Ferrate(VI) oxidation achieved 64.0% and 78.4% removal of naphthenic acids (NAs) at the dose of 200 mg/L and 400 mg/L Fe(VI) respectively, and NAs with high carbon number and ring number were removed preferentially. (1)H nuclear magnetic resonance ((1)H NMR) spectra indicated that the oxidation of fluorescing aromatics resulted in the opening of some aromatic rings. Electron paramagnetic resonance (EPR) analysis detected signals of organic radical intermediates, indicating that one-electron transfer is one of the probable mechanisms in the oxidation of NAs. The inhibition effect of OSPW on Vibrio fischeri and the toxicity effect on goldfish primary kidney macrophages (PKMs) were both reduced after ferrate(VI) oxidation. The fluorescing aromatics in OSPW were proposed to be an important contributor to this acute toxicity. Degradation of model compounds with ferrate(VI) was also investigated and the results confirmed our findings in OSPW study.

Comparison of Nitrilotriacetic Acid and [S,S]-Ethylenediamine-N,N′-disuccinic Acid in UV–Fenton for the Treatment of Oil Sands Process-Affected Water at Natural pH

“…Unfortunately, detailed information on the new peaks is not available in the literature. It was reported that one-ring aromatics have higher stability than two- and three-ring aromatics toward oxidation . Aromatics with two or more fused rings have higher electron density, leading to higher activity toward oxidation. , Moreover, aromatic compounds with greater size and increasing alkyl substitution have higher quantum yields, resulting in higher sensitivity toward photochemical oxidation. − The production of one-ring aromatics from the decomposition of two- and three-ring aromatics also explains the apparent stability of one-ring aromatics …”

“…The high removal of c-NAs and oxy-NAs in the UV–NTA–Fenton process suggests the high efficiency of this process on the degradation of total NAs in OSPW. Wang et al reported removal of c-NAs, NAs + O, and NAs + 2O in OSPW of 64.0%, −18.4%, and −18.0%, respectively, after treatment with 200 mg/L potassium ferrate­(VI). The negative removal of NAs + O and NAs + 2O was due to the reproduction of these species from the oxidation of c-NAs and the transformation of oxy-NAs at high n and z numbers to oxy-NAs at low n and z numbers.…”

Ferrate(VI) based chemical oxidation for the remediation of aged PCB contaminated soil: Comparison with conventional oxidants and study of limiting factors

“…Moreover, HFeO 4 is readily decomposed to Fe(V) and Fe(IV) species that are more reactive than Fe(VI) for oxidation process [11,18]. It is generally known that the ferrates species (Fe +IV to +VI) preferentially target pollutants with electron rich moieties such as phenols, anilines, amines, aromatics, alcohols and olefins in water [14,19,21,27]. However, its use has rarely been reported for soil remediation as correctly identified in a very recent review article [10].…”

“…On the other hand, Fe(VI) preferentially attacks electron-rich moieties and acts via mechanisms based on electron transfer as illustrated in equations 3 and 4 (R represents an organic compound) [6,18,20,21,27]. Attempts to identify the reaction by-products using GC-MS and then elucidate the Fe(VI) oxidation mechanism failed, probably due to the low PCB degradation extent and the complex organic contamination in the investigated soil.…”

Reactions of hydroxyl radicals with benzoic acid and benzoate

“…Water produced from mining operations, in particular, oil sands mining operations, contains solids, salts, and other organic compounds such as benzene, phenols, naphthenic acids (NAs) which are toxic to wildlife. 1,2 Despite the small amount of aromatic alkanoic acids such as benzoic acid (BA) in NAs, they increase the toxicity and recalcitrance of NAs in wastewater. 3 In addition, BA is a common recalcitrant contaminant which exists in domestic wastewater as well as other industrial wastewater, making it imperative to remove BA from waste water.…”