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Sadrzadeh M.,University of Alberta | Hajinasiri J.,University of Alberta | Bhattacharjee S.,Water Planet | Pernitsky D.,Suncor Energy
Separation and Purification Technology | Year: 2015

Nanofiltration (NF) is a promising advanced treatment technique for oilfield wastewaters. In this study, we performed a crossflow NF on model boiler feed water (BFW) obtained from a thermal in-situ bitumen recovery process called steam assisted gravity drainage (SAGD) with the intent to remove dissolved organic matter and silica. Nanofiltration with a tight NF membrane was selected as the treatment technique since it provided reasonable product quality in a single-stage process and was found to be more energy efficient than reverse osmosis (RO). Two different feed pH values, 8.5 and 10.5, were investigated. Total organic carbon (TOC) and Si rejection of approximately 98% and divalent cation rejection greater than 99% was achieved at both pH values. Higher total dissolved solids (TDS) rejection, but lower flux rates were seen at pH 8.5 compared to pH 10.5. Surface characterization of the fouled membranes indicated the presence of organics (primarily carbon and oxygen) and inorganics (mainly silicon and iron) in the fouling deposits. Larger amounts of deposit were seen at pH 8.5 compared to pH 10.5. Increasing feed pH from 8.5 to 10.5 recovered the water flux more than 20% which demonstrated the critical role of pH as a pulsation technique to reduce membrane fouling. Fluorescence excitation emission matrix spectroscopy (FEEMs) on the feed and permeate showed that the organic matter that passed through the membrane was mainly hydrophilic compounds. Overall, this research indicated that NF is a viable treatment process for silica and TOC removal for SAGD BFW. © 2014 Elsevier B.V. All rights reserved.

Nazaripoor H.,University of Alberta | Koch C.R.,University of Alberta | Bhattacharjee S.,Water Planet
Langmuir | Year: 2014

The effect of electrostatic force on the dynamics, morphological evolution, and drainage time of ultrathin liquid bilayers (<100 nm) are investigated for perfect dielectric-perfect dielectric (PD-PD) and ionic liquid-perfect dielectric (IL-PD) bilayers. The weakly nonlinear "thin film" equation is solved numerically to obtain spatiotemporal evolution of the liquid-liquid interface responses to transverse electric field. In order to predict the electrostatic component of conjoining/disjoining pressure acting on the interface for IL-PD bilayers, an analytical model is developed using the nonlinear Poisson-Boltzmann equation. It is found that IL-PD bilayers with electric permittivity ratio of layers (lower to top), εr, greater than one remain stable under an applied electric field. An extensive numerical study is carried out to generate a map based on εr and the initial mean thickness of the lower layer. This map is used to predict the formation of various structures on PD-PD bilayer interface and provides a baseline for unstable IL-PD bilayers. The use of an ionic liquid (IL) layer is found to reduce the size of the structures, but results in polydispersed and disordered pillars spread over the domain. The numerical predictions follow similar trend of experimental observation of Lau and Russel. (Lau, C. Y.; Russel, W. B. Fundamental Limitations on Ordered Electrohydrodynamic Patterning; Macromolecules 2011, 44, 7746-7751). (Graph Presented). © 2014 American Chemical Society.

Jian C.,University of Alberta | Tang T.,University of Alberta | Bhattacharjee S.,University of Alberta | Bhattacharjee S.,Water Planet
Energy and Fuels | Year: 2014

In order to investigate the aggregation mechanisms of asphaltenes in toluene, a series of molecular dynamics simulations were performed on Violanthrone78-based model asphaltenes with different aliphatic/aromatic ratios. Our simulation results show that the attraction between poly-aromatic cores is the main driving force for asphaltene aggregation in toluene, and that the extent of aggregation is independent of the aliphatic/aromatic ratios. On the other hand, analysis of the aggregated structures indicates that long side chains do hinder the formation of large direct parallel stacking structures. In contrast with water as a solvent, toluene exhibits attractive interactions with both the aliphatic and aromatic regions of the asphaltenes, hence reducing the size and stability of the asphaltene aggregates. Our findings help to elucidate, at a molecular level, the different solubility behaviors of asphaltenes in toluene and in water. © 2014 American Chemical Society.

Nazaripoor H.,University of Alberta | Koch C.R.,University of Alberta | Sadrzadeh M.,University of Alberta | Bhattacharjee S.,Water Planet
Soft Matter | Year: 2016

The influence of electrostatic heterogeneity on the electric-field-induced destabilization of thin ionic liquid (IL) films is investigated to control spatial ordering and to reduce the lateral dimension of structures forming on the films. Commonly used perfect dielectric (PD) films are replaced with ionic conductive films to reduce the lateral length scales to a sub-micron level in the EHD pattering process. The 3-D spatiotemporal evolution of a thin IL film interface under homogenous and heterogeneous electric fields is numerically simulated. Finite differences in the spatial directions using an adaptive time step ODE solver are used to solve the 2-D nonlinear thin film equation. The validity of our simulation technique is determined from close agreement between the simulation results of a PD film and the experimental results in the literature. Replacing the flat electrode with the patterned one is found to result in more compact and well-ordered structures particularly when an electrode with square block protrusions is used. This is attributed to better control of the characteristic spatial lengths by applying a heterogeneous electric field by patterned electrodes. The structure size in PD films is reduced by a factor of 4 when they are replaced with IL films, which results in nano-sized features with well-ordered patterns over the domain. © The Royal Society of Chemistry 2016.

Agency: National Science Foundation | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 148.90K | Year: 2016

The broader impact/commercial potential of this Small Business Innovation Research Phase I project is that it delivers a novel polymeric membrane filtration material that is resistant to fouling by sticky organic matter present in wastewaters treated in membrane bioreactors (MBRs). Membrane fouling is a leading problem encountered in MBR systems, and is poorly served by incumbent technologies. Filtration membranes made from the proposed engineered polymer material could be significantly more fouling resistant, easily cleanable, and display enhanced chemical resilience compared to conventional polymeric membranes used in commercially available MBRs. The global MBR applications market is at its early growth phase, with no clear dominant technology and market leader. The proposed membrane technology will be highly differentiated and is expected to substantially improve the economics and reliability of MBRs. The technical objectives of this Phase I research project are to develop a flat sheet membrane with (1) high water permeability, (2) hydrophilic and super-oleophobic surface properties, (3) high mechanical/thermal/acid/base resistance, and (4) high oxidant resistance. Membranes with high water permeability require lower operating pressures (lower energy requirements). Membranes that are extremely hydrophilic are more fouling resistant, and membranes that are highly oleophobic are more oil-tolerant. Mechanical, thermal, and chemical (acid, base, chlorine) tolerance are critical for enabling aggressive membrane cleaning. The oxidant tolerance is specifically desired to render the membranes functional in high purity oxygen membrane bioreactors (HPO-MBR), where high organic loading is maintained in persistently higher oxidation potential (high dissolved oxygen) media. Thus, polymeric membranes with better long-term oxidant resistance could exhibit longer lifetimes, and lower cleaning frequencies and downtime in an HPO-MBR process. This project aims to molecularly design the side chain functionality of the backbone polymer entity to create such an oxidation tolerant membrane. A polymeric membrane with these specifications has never been made, but would be very attractive to customers that need to treat wastewater with high chemical oxygen demand (COD) in advanced MBR processes.

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