Traditional kaolinite (Kaol) exfoliation and delamination techniques often cause the fracture of two-dimensional (2D) Kaol platelets. In this work, a modified procedure for Kaol delamination was developed to mitigate 2D platelet fragmentation and control the morphology of the obtained platelets. This modified procedure combined mechanical and chemical techniques by applying high-power pulsed ultrasound and using urea and surfactant solutions. The ultrasonicator was set to a power of 500 W (20 kHz), with pulses of 10 s on and 1 min off for a total duration of 3 h. A 50 mass% urea-water solution was used, with the addition of one of four different surfactants near their solubility limits: cetyltrimethylammonium bromide (CTAB), polyvinylpyrrolidone (PVP K30, average molecular weight (MW): 40 kg/mol), PVP-10 (average MW: 10 kg/mol), and sodium cholate (SC). The platelet morphologies obtained from the delaminated Kaol were characterized by scanning electron microscopy and the associated surface area variation was measured using the Brunauer-Emmett-Teller (BET) method. The circular equivalent diameter and circularity were evaluated by 2D image analysis of the delaminated platelets; the results were then compared with those obtained by the BET method to evaluate the effect of surfactants on Kaol delamination. The type and quantity of added surfactants influenced the morphology of the delaminated Kaol In particular, the addition of 2 g PVP (K30), 13.3 g PVP (K30), 2 g CTAB, or 8.6 g SC helped to preserve the original Kaol shape determined by 2D image analysis. This was confirmed by the similar circularity distribution of the untreated Kaol at 100% ultrasonication power. However, the aggregation of Kaol platelets decreased after delamination. Thus, a combination of urea and an appropriate surfactant decreased the aggregation of Kaol platelets after delamination. The BET surface areas of the raw and delaminated Kaol were similar. The results obtained by the two different approaches demonstrated that 2D image analysis can describe the morphology change and aggregation of delaminated Kaol, whereas the BET method can quantitatively describe the delaminated Kaol.

The extraction of bitumen from oil sands using steam-assisted gravity drainage (SAGD) produces a considerable amount of oily process water that must be recycled. Ceramic membranes are well suited for this task, but membrane fouling remains a significant barrier to their widespread application. Bituminous clays in produced water are heavily charged and interact with the charged surfaces of ceramic membranes in a way that reduces membrane performance. To address this problem, the surfaces of commercially available multi-lumen tubular ceramic membranes were chemically modified using several charge-neutral polyethylene oxide (PEO)-based organosilanes. Membranes with a pore size of 10 nm and selective layers of either gamma-Al2O3 or TiO2 were modified based on protocols previously used on small-scale ceramic membrane disks and challenged with SAGD-produced water. Results indicate that the modification leads to an improvement in membrane performance. Modification of gamma-Al2O3 membranes by a 30% solution of straight-chain PEO-silane increased permeate flux by factors as high as 2.9. Modification of TiO2 membranes also improved permeate flux. Flux recovery factors upon backflushing increased from 1.3 to 1.6. Furthermore, flux values for gamma-Al2O3 membranes ranged between 50 and 150 Lmh and increased over time, while flux values for TiO2 membranes ranged between 220 and 350 Lmh and declined slightly over time. This indicates that gamma-Al2O3 is a stronger adsorbent for bituminous foulants than TiO2, with foulants being adsorbed quickly and subsequently released during filtration and backflushing. Finally, the decline in performance when switching to a SAGD feed, with a higher pH, total organic carbon and alkalinity, was significantly less severe for modified TiO2 membranes compared to unmodified counterparts. Based on these results, surface modification of tubular ceramic membranes with PEO-based silanes was successful in improving the rejection of bituminous foulants from the membrane surface.

Current oil sands extraction technologies expend a significant amount of energy in the treatment and recycling of the oily process waters that are generated during the extraction process. Ceramic membranes are promising candidates for enhancing the energy efficiency of the produced water deoiling process due to their low energy requirements. However, membrane fouling by bituminous solids remains a significant barrier to the widespread acceptance of membranes in this application. As an alternative to chemical membrane cleaning, a steam regeneration technique was applied to ceramic membranes in the filtration of steam-assisted gravity drainage (SAGD) produced water. This technique involved the periodic injection of steam directly into the membrane feed channels, and was applied in conjunction with conventional permeate backflushing. Tubular multilumen ceramic membranes with titania selective layers having pore sizes of 5 or 10 nm were used. Support layers were composed of either alumina or titania. Optimal transmembrane pressure and crossflow velocity settings were found to be 50 psi and 1 m/s over the investigated ranges. Membrane permeate fluxes increased from 50 to 200 Lmh when the steam regeneration method was activated. Flux enhancement was found to depend on the initial duration of filtration without steam injection, which results in significant irreversible fouling. Steam regeneration also improved membrane separation performance, increasing total organic carbon, sulfate and chloride retention by as much as 19%, 17% and 10%, respectively. Steam regeneration is a continuous in-process method that offers the possibility of recycling the oleophilic cake released from the surface of the membrane. The cake can be sent to a flotation unit upstream of the membrane system, allowing bituminous fines to be entrained in the main oil stream. This offers many possibilities for waste minimization, particularly in remote areas where cleaning fluids that are produced when membranes are chemically cleaned would need to be transported and treated off-site.

Industrial oily wastewaters often contain many recalcitrant species, such as dissolved metal ions, salts, bitumen, clays and humics. These species possess surface charges due to acidic, basic and amphoteric groups, thus leading to severe ceramic membrane fouling. To address this problem, ceramic membrane surfaces were chemically modified with highly hydrophilic PEO-based organosilanes. Three different membrane surface layers (ZrO2 TiO2, ZrO2 and TiO2) were modified at varying silane concentrations and reaction times to test their reactivity and stability. All modified membranes maintained hydrophilic behavior, as shown by water contact angles of < 25 degrees and pure water fluxes of 500-600 Lmh. Modified TiO2 membranes exhibited superhydrophilicity with contact angles < 10 degrees. It was found that TiO2 membranes were the most reactive, achieving maximal silane surface coverage at lower concentrations and reaction times, followed by ZrO2 and ZrO2-TiO2 membranes. The silylated TiO2 membrane was also the most thermally stable surface at 130 degrees C and 160 degrees C. Increasing the length of the PEO chain in the silane was also found to increase the thermal stability of the silane surface. TiO2 membranes modified with the higher molecular weight silane maintained 97% of the silane at the membrane surface when exposed to heat at 130 degrees C. In enhancing the suitability of ceramic membranes in challenging applications; titania membranes over zirconia and zirconia-titania should be used and modified with PEO-silanes containing 9-12 repeat units to ensure maximal surface coverage and enhanced thermal stability.

Minor components found in biodiesel can affect its stability and cold flow properties. Without extensive post treatments, trace compounds such as sterol glycosides (SG) can remain at unacceptable levels in finished biodiesel fuels. This study proposes to remove SG from reacted Fatty Acid Methyl Ester (FAME) mixtures using ultrafiltration. Degummed soybean oil was transesterified using methanol and a catalyst (sodium methoxide). The mixtures were immediately ultrafiltered after the reaction and the FAMEs from the retentate and permeate were analyzed for SG. The highest separation for SG (86 %) was obtained when the reaction conditions were 0.7 wt.% catalyst and 4:1 MeOH:Oil ratio. The lowest separation (0%) was observed at 0.3 wt.% catalyst and 4:1 MeOH:Oil ratio. The higher separations were explained by the deprotonation of the hydroxyl groups on SG. This decreased the solubility of SG in the reacted FAME phase. The separation was lowest, when unreacted oil along with monoacylglycerides (MG) and diacylglycerides (DG) solubilized SG in the reacted mixture. The separation was also low when high methanol to oil ratios were used in the transesterification. The lowest concentration of SG measured in FAMEs treated by ultrafiltration was 3.4 ppm. The results indicate that ultrafiltration is an effective method to remove SG from soybean FAMEs.

Pretreatment is key to the success of any fine filtration process. Precoat filtration is a common method to reduce fine particulate matter in feed streams. In this study, precoat filters were formed by the deposition of the diatomaceous earth (DE) or twinned alumina nanosheets (TAN) particles on a substrate. The TAN particles were produced via metal salt hydrolysis. The performance of the precoat filters was investigated during the constant-pressure filtration of a bentonite solution. The results showed that the TAN precoat exhibited enhanced flow properties and reduced the turbidity of the filtrate more rapidly than either of the DE precoats. The TAN precoat reached the required turbidity level of <= 0.10 NTU at a flux that was up to 28 times higher than the fluxes obtained by the DE precoats. The superior performance of the TAN pre-coat was explained by (1) the ability of the TAN precoat to resist compaction during filtration due to the unique twinning of the alumina nanosheets forming the TAN particles, (2) the strong attractive forces between the bentonite and TAN particles based on their opposite surface charges, and (3) the isotropic permeability of the TAN aggregates. (C) 2017 Elsevier B.V. All rights reserved.

The effect of Phosphotungstic acid (PWA) on the proton conductivity and morphology of zirconium phosphate (ZrP), porous polytetrafluoethylene (PTFE), glycerol (GLY) composite membrane was investigated in this work. The composite membranes were synthesized using two approaches: (1) Phosphotungstic acid (PWA) added to phosphoric acid and, (2) PWA + silicic acid were added to phosphoric acid. ZrP was formed inside the pores of PTFE via the in situ precipitation. The membranes were evaluated for their morphology and proton conductivity. The proton conductivity of PWA–ZrP/PTFE/GLY membrane was 0.003 S cm−1. When PWA was combined with silicic acid, the proton conductivity increased from 0.003 to 0.059 S cm−1 (became about 60% of Nafion’s). This conductivity is higher than the proton conductivity of Nafion–silica–PWA membranes reported in the literature. The SEM results showed a porous structure for the modified membranes. The porous structure combined with this reasonable proton conductivity would make these membranes suitable as the electrolyte component in the catalyst layer for direct hydrocarbon fuel cell applications.

The extraction of bitumen using oil extraction and recovery processes such as SAGD (steam assisted gravity drainage) produces oily process waters that must be treated and recycled when possible. Ceramic membranes are well suited for this task. However, ceramic membranes in aqueous media have a pH dependent surface charge. It was hypothesized that these surface charges are responsible for the high fouling of ceramic membranes in treating wastewaters containing bituminous fines. To maintain desirable hydrophilic properties without surface charges, a highly hydrophilic and neutral organosilane was used to modify the surface of ceramic membrane disks. Membranes having pore sizes of 150 kDa, 300 kDa and 0.14 mu m were modified using this organosilane. The ceramic membranes were then used in the filtration of SAGD produced water. Results indicate that the modification was successful in mitigating the irreversible fouling caused by bituminous ultrafines. The permeate flux of the 150 and 300 kDa membranes more than doubled after modification in a 20% silane solution. Furthermore, the filtered water obtained from the modified membranes was of superior quality, to that of the untreated membrane, as evidenced by total organic carbon analysis. All of the ceramic membranes tested were shown to reduce the particle sizes in the produced water from >200 nm in the feed to <40 nm in the permeate.

Surfactant molecules have high surface activity, and can therefore influence the self-assembly of nanomaterials. The self-assembly of twinned boehmite nanosheets into porous 3D superstructures will be greatly affected by the presence of surfactant monomer and micelles in various ethanol–water mixtures. It should be possible to influence the shape, thickness, and twinning of boehmite nanosheets by varying the concentration of the surfactant and ethanol in the synthesis mixture to obtain high porosity 3D superstructures.The critical micelle concentration (CMC) of cationic surfactant cetyl trimethylammonium bromide (CTAB) was determined in 0, 12.5, 25, 37.5, and 50vol% ethanol–water mixtures. The effect of CTAB on boehmite particle morphology and superstructure formation during self-assembly was explored at the CMC, and at 20%, 15%, 10%, 5% below and above the CMC of CTAB in various ethanol–water mixtures.Boehmite nanosheets with controllable shape and thickness were successfully formed in various ethanol–water mixtures. Prior to micelle formation, the average thickness of nanosheets formed in 0vol%, 25vol%, and 50vol% ethanol–water were 200nm, 110nm and 100nm, respectively. Micelle formation reduced the availability of surfactant molecules for particle templating, broadening the nanosheet thickness distribution. Micelle formation was inhibited in 50vol% ethanol–water due to the increase in Gibbs free energy needed to form micelles relative to the Gibbs free energy of micelles in 0vol% or 25vol% ethanol–water. The enthalpy-driven process gives greater control over the nanosheet thickness, producing particles with narrow thickness distributions. In general, the CMC represented the point at which control is lost over the thickness of the nanoplatelets; increasing the surfactant concentration above the CMC increased the thickness of the nanoplatelets.Particle twinning during crystal growth produced an interconnected 3D network of boehmite particles with high porosity (79–88%) and hydraulic permeability (62.4–809mD). The addition of ethanol during synthesis increased the porosity and reduced the bulk density of the 3D superstructures by 8–11% and 26–28%, respectively, and yielded a ten-fold increase in the hydraulic permeability. The integrity of the porous 3D network was maintained upon calcination, suspension in water and deposition by filtration onto cellulose filter paper.

Sterol glycosides (SG) are known to cause filter blocking problems in biodiesel use. The extraction and quantitative analysis of SG is difficult due to its low problematic concentration and its compatibility with biodiesel. The purpose of this study is to develop a method to quantify SG in FAME and biodiesel using gas chromatography and other equipment found in laboratories performing routine biodiesel analyses. SG was isolated from FAME using n-dodecane, acidification and cold soaking, followed by cold centrifugation at −8 to −15 °C. The solids obtained were further separated by phase partition with a Folch wash, followed by a final n-dodecane rinse. This solution was analyzed by GC-FID using the operating conditions outlined in ASTM D6584. A calibration curve for SG was produced and a first order fit gave a value of r 2 = 0.992. Reproducibility tests were performed on soybean FAME and B100 canola biodiesel samples spiked with SG. The recovery of SG by the new method was found to be 99 % for soy FAME with a standard deviation of 0.7 and 100 % for B100 canola with a standard deviation of 3.5 %. The reproducibility based on two standard deviations of the predicted concentration for all 12 spiked samples studied in this work was 2.4 ppm.

In this work, intrinsically-porous aggregates of nanosheets having mono-, di-, and tri-modal particle size distributions were synthesized to produce densely-packed dynamic membranes. Alumina nanosheets were synthesized in 0, 25, and 50vol% ethanol-water mixtures (Al-0, Al-25, and Al-50, respectively). Using dynamic image analysis, it was determined that the alumina nanosheets twinned to form aggregate superstructures of distinct size distributions at each synthesis condition. The aggregates were intrinsically porous with three-dimensional pore connectivity. Dynamic membranes (DMs) were formed by the deposition of these aggregates on a substrate. The effect of ethanol content in the synthesis mixture on the performance of the DMs was investigated during the constant-pressure filtration of a bentonite solution. The results show that the Al-50 DM had the best performance based on flux and turbidity removal. The Al-50 DM reached the required turbidity level of <0.10 NTU at a flux that was 177% and 12% higher than the fluxes obtained by the Al-0 and Al-25 DMs, respectively. The superior performance of the Al-50 DM was explained by the presence of three aggregate size distributions providing optimal packing in the synthesized material. This reduced interstitial pores and resulted in a packing density of 74.7 –78.5% versus 54.0–54.2% for Al-0.

The objective of this work was to examine fuel cells as a possible alternative to the diesel fuel engines currently used in railway locomotives, thereby decreasing air emissions from the railway transportation sector. We have investigated the performance of a phosphoric acid fuel cell (PAFC) reactor, with n-hexadecane, C16H34 (a model compound for diesel fuel, cetane number = 100). This is the first extensive study reported in the literature in which n-hexadecane is used directly as the fuel. Measurements were made to obtain both polarization curves and time-on-stream results. Because deactivation was observed hydrogen polarization curves were measured before and after n-hexadecane experiments, to determine the extent of deactivation of the membrane electrode assembly (MEA). By feeding water-only (no fuel) to the fuel cell anode the deactivated MEAs could be regenerated. One set of fuel cell operating conditions that produced a steady-state was identified. Identification of steady-state conditions is significant because it demonstrates that stable fuel cell operation is technically feasible when operating a PAFC with n-hexadecane fuel.

The performance of a direct hydrocarbon phosphoric acid fuel cell, PAFC, was investigated using petroleum diesel, biodiesel, and n-hexadecane as the fuels. We believe this is the first study of a fuel cell being operated with petroleum diesel as the fuel at the anode. Degradation in fuel cell performance was observed prior to reaching steady state. The degradation was attributed to a carbonaceous material forming on the surface of the anode. Regardless of the initial degradation, a steady-state operation was achieved with each of the diesel fuels. After treating the anode with water the fuel cell performance recovered. However, the fuel cell performance degraded again prior to obtaining another steady-state operation. There were several observations that were consistent with the suggestion that the carbonaceous material formed from the diesel fuels might be a reaction intermediate necessary for steady-state operation. Finally, the experiments indicated that water in the phosphoric acid electrolyte could be used as the water required for the anodic reaction. The water formed at the cathode could provide the replacement water for the electrolyte, thereby eliminating the need to provide a water feed system for the fuel cell.

A continuous-flow membrane reactor was constructed for the production of fatty acid methyl ester (FAME) from waste vegetable oil with high free fatty acid (FFA) content. FAME was produced via base-catalysed transesterification with methanol at two FFA levels: 4.8 and 10mass%. The effect of the ceramic membrane pore size on the separation of soap and triglycerides from the FAME in the reactor was investigated. In all cases, the triglyceride was completely retained in the reactor, yielding free and total glycerine contents in the produced FAME significantly below the maximum limits of the ASTM D6751 standard. The soaps produced in the reaction mixture were not completely retained in the reactor and did not affect the FAME production process. (c) 2012 Canadian Society for Chemical Engineering

Composite membranes composed of modified S or Si-zirconium phosphate (ZrP), porous polytetra-fluoethylene (PTFE) and, glycerol (GLY) were synthesized in this work. ZrP was precipitated via the insitu reaction of zirconium oxychloride (ZrOCl2) with phosphoric acid (H3PO4). Silicic acid and sulphuric acid were introduced as additives to phosphoric acid with variable Si/P or S/P mass ratios in the acid solution/suspension. The modified membranes were investigated as electrolytes for direct hydrocarbon fuel cells operating at temperatures similar to 200 degrees C. The present work shows that adding a small amount of silicic acid to phosphoric acid enhanced the proton conductivity, i.e. by having a Si/P mass ratio of (0.01) in the acid solution/suspension, the Si-ZrP/PTFE/GLY membrane conductivity was 0.073 S cm(-1). This value approached the conductivity of Nafion (0.1 S cm(-1)). The results also showed that adding sulphuric acid to phosphoric acid led to a significant decrease in the membrane's proton conductivity. SEM analysis results showed a porous structure of the Si-ZrP modified membranes. This porous structure combined with the high proton conductivity reported, would make them good candidates for catalyst layer supports in fuel cell applications. (C) 2012 Elsevier B.V. All rights reserved.

Ethanol is a biofuel, produced through the fermentation of sugars derived from biomass. Its usefulness as a fuel is limited by the energy intensive nature of the ethanol separation process. The ethanol recovery process is inefficient due to the dilute nature of the fermentation product and the presence of the ethanol−water azeotrope. This investigation presents a new hybrid separation process for energy efficient ethanol recovery. The new process is a hybrid of distillation and pervaporation. However, as opposed to most other hybrid processes, the distillation and pervaporation processes are combined into single unit. An overview of the proposed system was provided and differences to the conventional separation process were highlighted. A mathematical model was derived to explain the transport phenomena occurring in the hybrid process. The model was then used to compare the process to distillation. It was shown that the hybrid process is capable of breaking the ethanol-water azeotrope. It was also demonstrated that the pervaporation process, which is associated with both material and energy transfer, induces partial condensation of the vapor and thereby affects the efficiency of vapor−liquid contacting. Simulations were presented to show the impact of reflux ratio and pervaporation flux on the performance of the process.

Biodiesel produced from lipid sources is a clean-burning, biodegradable, nontoxic fuel that is free of aromatic hydrocarbons. Current biodiesel production processes are tedious and involve two to three reaction steps each followed by separation and purification. Process integration of reaction and separation in a single step within a membrane reactor (MR) offers several advantages over conventional reactors.This investigation is aimed at studying the effect of membrane flux and residence time on the performance of a membrane reactor in treating a variety of raw and used feedstocks. A membrane reactor having three selectable reactor volumes was designed to decouple the effect of residence time in the reactor from membrane flux on the performance of the reactor. Low free fatty acid (FFA) oils (FFA < 1%), i.e. canola, corn, sunflower and un-refined soy oils, and high FFA waste cooking oil (FFA = 5%) were base transesterified and the quality of the biodiesel produced was determined in terms of free glycerine, mono-glyceride, di-glyceride and tri-glyceride content. All oils were base transesterified without pretreatment.Based on the composition of the final product, the MR could be operated at the upper limit of the flux tested (70 L/m(2)/h) and a residence time of 60 min. The ASTM D6751 and EN 14214 standards for glycerin and glycerides were reached in the washed biodiesel product for all feedstocks and run conditions. The operating pressure in the reactor was exceeded at 70 L/m(2)/h in treating waste oils and pre-treated corn oil. For these oils, reasonable operating pressures in the reactor were reached at a membrane flux of 30-40 L/m(2)/h. The quality of the washed biodiesel always met ASTM and EN standards. The FAME produced from WCO at intermediate fluxes and high residence times met the ASTM and EN standards without water washing. (C) 2011 Elsevier Ltd. All rights reserved.

International standards (e.g., ASTM D6751 and EN14214) limit the presence of free glycerol in biodiesel. The traditional water wash method for removing glycerol from crude fatty acid methyl esters (FAME) obtained in the production of biodiesel results in waste waters that cannot be readily discharged. To circumvent the water wash purification method, a membrane separation system using ceramic membranes was designed, constructed and tested for the removal of glycerol from crude FAME from a biodiesel production process. Ceramic membranes in the ultrafiltration (0.05μm) and microfiltration (0.2μm) ranges were tested at three different operating temperatures: 0, 5 and 25°C. All runs separated glycerol from the crude FAME. International standards for glycerol content in biodiesel were met after 3h when utilizing the ultrafiltration membrane setup at 25°C with a concentration factor greater than 1.6.

In this investigation, the effects of some important parameters on the flow patterns in a narrow vertical channel for counter-current vapour-liquid flow of an ethanol-water system were studied. The parameters included the liquid Reynolds number, ethanol concentration, contact angle, and pressure drop. The vapour phase velocity profile was significantly influenced by the pressure drop through the channel. The ethanol concentration and liquid Reynolds number were found to have a significant impact on the liquid holdup (average film thickness) as well as the velocity profiles in the liquid and vapour phases. In the ranges studied, the contact angle and pressure drop were found to have a negligible effect on the liquid holdup.

Ethanol is a renewable biofuel produced through the fermentation of sugars obtained from biomass. However, the usefulness of ethanol as a fuel is partly limited by the energy intensive nature of the separation processes employed in its production. A hybrid pervaporation–distillation separation process was developed for the efficient separation of ethanol from water. An experimental system was constructed to investigate process performance. The system employed vertically oriented, commercially available, tubular NaA zeolite membranes. This configuration allowed both the dephlegmation and pervaporation processes to be carried out within the same unit. The process was simulated using a model that included coupled heat and mass transfer across the vapour–liquid interface as well as permeation through the pervaporation membrane. Experiments were performed at a variety of feed concentrations, feed flow rates, reflux ratios and permeate pressures. The hybrid process produced ethanol at concentrations well above the ethanol–water azeotrope and yielded improved performance compared to distillation for the same operating conditions. The experimental results were used to validate the simulations and to study the impact of important model parameters. The model predicted the experimental results very well, despite requiring only one fitting parameter. The hybrid process appears to be very efficient for ethanol–water separation and the validated design model will allow detailed process optimization to be performed in the future.