Ozonation of Naphthenic Acids in Water: Kinetic Study

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A major challenge the oil sands industries are facing is the urgent need to treat large amounts of oil sands process‐affected water (OSPW). OSPW is toxic to many species mainly due to the presence of naphthenic acids (NAs). Ozonation can significantly reduce both concentration and toxicity of the NAs. Unfortunately, this method suffers from its relatively high cost. To enhance NAs removal, we initiated heterogeneous catalytic ozonation of synthetic OSPW. Two types of catalysts were investigated: i) alumina supported metal oxides, and ii) unsupported catalysts. The alumina supported oxides included MnO2, MnO2/Co3O4, and MnO2/Li2O, while the unsupported catalysts were alumina and activated carbon (AC). All tested catalysts enhanced the ozone removal of NAs. Specifically, AC was found to be a very effective catalyst in addition to its adsorbability. AC significantly enhanced the removal of NAs and COD, the detoxification of the OSPW, and the biodegradability of NAs. For 85 % removal of NAs, the AC catalyzed ozonation needed 15 min whereas over 45 min were required by its non‐catalyzed counterpart. By using AC catalyzed ozonation, the efficiencies of detoxification and COD removal were both over four times and the biodegradability of the synthetic OSPW was over five times of those treated by non‐catalyzed ozonation. The mechanism study confirmed that due to the presence of AC the hydroxyl radical concentration increased 31 %, resulting in 26.4 % reduction in ozone consumption compared to non‐catalyzed ozonation. The removal of NAs was enhanced because of the higher oxidation power of hydroxyl radicals than molecular ozone.

Section: Methodssupporting

confidence: 55%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Heterogeneous catalytic ozonation of naphthenic acids in water

jibouri

Upreti

2018

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Application of mass balance models in the process of ozone removal of naphthenic acids from water

jibouri

Upreti

2016

Self Cite

The oil sands process‐affected water (OSPW), produced in large amounts during the extraction of crude oil from oil sands, is toxic mainly due to the presence of naphthenic acids (NAs), among other constituents. Ozonation is an effective method for the removal of NAs. To provide information for better control of NAs ozonation, models based on mass balance were developed in this study to predict the concentration profiles of commercial NAs, dissolved ozone, and gaseous ozone during the process. It was found that the developed models successfully predicted the concentrations of commercial NAs and gaseous ozone. For the dissolved ozone concentration, the developed model can predict the equilibrium concentrations well. However, the actual ozone consumption was higher than that predicted by the model at the initial period of the ozonation process. This deviation possibly resulted from the inapplicability of the gas‐liquid equilibrium conditions at the initial high rate stage of the reaction. In addition, the Henry's law constant and the overall mass transfer coefficient for the given system were determined experimentally. Also investigated in this study was the effects of inlet gaseous ozone concentration into the reactor on the removal of NAs and on the concentration of dissolved ozone. As expected, the increase in inlet ozone concentration enhanced the removal of NAs and increased the concentration of dissolved ozone.

Adsorption of naphthenic acids from oil sand process‐affected water with water‐insoluble poly(β‐cyclodextrin‐citric acid)

Liang

Zou

2019

With polyvinyl alcohol as the main chain, a water‐insoluble poly(β‐cyclodextrin‐citric acid) was prepared as a supramolecular adsorbent for the treatment of oil sand process‐affected water (OSPW) containing naphthenic acids (NAs). FT‐IR, TGA, and SEM were used for the characterization of adsorbent, and an automatic infrared oil analyzer was used to monitor the concentration change of NAs in the water. The adsorption behaviour and mechanism were explored by adsorption kinetics and thermodynamic studies. The results showed that the adsorption process could be described well with the Langmuir isothermal adsorption model and quasi‐second‐order kinetic model, which indicated that the host‐guest interaction of β‐cyclodextrin promoted the adsorption of NAs. The discussion regarding pH indicated that the neutral condition (pH = 7) was considered the best. In addition, a molecular dynamics simulation was carried out using a Materials Studio package purchased from Accelrys to verify that the structure with polyvinyl alcohol as main chain was beneficial to adsorption. The excellent adsorption capacity (qmax was 193.42 mg · g−1) and reusability of the poly(β‐cyclodextrin‐citric acid) indicated its potential as practical adsorbent for the treatment of OSPW.