Removal of acid-extractable organics from oil sands process-affected water using carbon-based adsorbents
Abstract
In surface mining process, 1.9 volumes of freshwater are used for each volume of bitumen produced and the used water, called oil sands process-affected water (OSPW), is stored in tailings ponds. Acid-extractable organics (AEO), one of the components of OSPW, are believed to be the main component of toxicity in OSPW, and create harmful effects to aquatic organisms, mammals and birds. To discharge OSPW into environment safely and reclaim the tailings ponds into natural ecosystem, the objective is to remove 90-99% AEO from OSPW. Canada has abundant resources of biomass waste materials to prepare biochar and activated carbon (AC), which can be applied for the removal of AEO from OSPW. In this thesis, the impact of biochar and AC properties, and synthesis methods for the removal of AEO from OSPW have been studied.
Aspen wood AC samples were prepared by chemical (H3PO4) and physical (CO2) activation methods, and characterized and tested for the removal of AEO from steam-assisted gravity drainage (SAGD) water and OSPW. The role of physical properties of AC for AEO removal was investigated. The surface area and total pore volume of AC were positively correlated with AEO removal of SAGD water and OSPW.The impact of biochar properties on AEO adsorption from OSPW was studied. Biochar from wheat straw with the highest ash content (14 %) had the highest adsorption capacity (0.59 mg/g). The adsorption capacity had a positive correlation with metal content (mainly Al and Fe) of biochar. These results indicated that the metal sites acted as Lewis acids that can form coordination bonds with the naphthenates, the main constituent of the AEO. The influence of physical properties of carbon-based adsorbents on AEO adsorption kinetics was also investigated. As expected, there were diffusion limitations when adsorbing AEO onto microporous adsorbents, while larger pore materials were free of intra-particle diffusion limitations, as confirmed by the adsorption of alkylated cyclopentane carboxylic acid. The outcome of this research provides an insight into the application of biomass based adsorbents for AEO adsorption.
Description
Keywords
Engineering--Chemical
Citation
Bhuiyan, T. (2017). Removal of acid-extractable organics from oil sands process-affected water using carbon-based adsorbents (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/27625