Linh D. Do

Algae, Canola, or Palm Oils—Diesel Microemulsion Fuels: Phase Behaviors, Viscosity, and Combustion Properties

Vegetable oils are being considered as a renewable energy alternative for diesel. The high viscosity of vegetable oils causes injector fouling and durability problems in compression–ignition engines. Microemulsification can be used to reduce vegetable oil viscosity without complex chemical transformation processes. The goal of our work is to formulate reverse micellar microemulsions of vegetable oils and No. 2 diesel fuel blended with ethanol using different combinations of surfactants and co-surfactants. Ethanol, also a renewable fuel, was used as a viscosity modifier. We studied three vegetable oils (canola, palm, and algae oils) to blend with diesel fuel. The microemulsion fuels were tested for temperature stability, viscosity, water tolerance, and their combustion performance in terms of flame radiation and pollutant (CO, NOx) emissions. With appropriate surfactant and co-surfactant systems, we successfully formulated canola and algae/diesel microemulsions with cloud points and points that satisfy the ASTM standards. Among all formulations, palm/diesel microemulsion fuels solidified at 6–6.5°C due to high saturated triglyceride content. While the formulated microemulsion fuels had approximately 10% lower heating value than diesel fuel, their CO emission and flame radiation were superior to those of diesel fuel. NOx emissions were also lower with the blends containing no nitrate additives, but were higher than with diesel fuel in the presence of nitrate additives. Thus, these results show that microemulsification can produce biofuels with desirable viscosity, fuel properties can be adjusted via formulation variables, and microemulsions can replace chemical processes for producing biofuels.

Colloid‐Enhanced Ultrafiltration of Chlorophenols in Wastewater: Part IV. Effect of Added Salt on the Surfactant Leakage in Surfactant Solutions and Surfactant–Polymer Mixtures

Abstract The critical aggregation concentration (cac) in surfactant–polymer mixtures approximates a lower limit to the surfactant concentration in the permeate (surfactant leakage) in polyelectrolyte micellar‐enhanced ultrafiltration. Here, the cac was measured at different salinities by using surface tension measurements. It was found that the cac increases slightly with the addition of simple salt, then the cac value decreases at higher salt concentration. The critical micelle concentration (CMC), which approximates surfactant leakage in micellar systems (no polymer), decreases monotonically with increasing salinity for ionic surfactants. The surfactant leakage in colloid‐enhanced ultrafiltration (CEUF) processes is investigated by using a dialysis method in the presence of three phenolic solutes with various degrees of chlorination: 2‐monochlorophenol (MCP), 2,4‐dichlorophenol (DCP), and 2,4,6‐trichlorophenol (TCP). Cetylpyridinium chloride (CPC) or n‐hexadecylpyridinium chloride is used as a cationic surfactant; and sodium poly(styrenesulfonate) (PSS) is used as an anionic polyelectrolyte. The effect of salinity and type of colloid is focused on here. In the absence of added salt, the cac can be over an order of magnitude less than the CMC, as can be surfactant leakage with added polymer. The added salt reduces the surfactant leakage in the micellar solution due to CMC reduction in the presence of electrolyte. In the surfactant–polymer mixture, the surfactant leakage is dramatically affected by salinity.

Phase behaviors, fuel properties, and combustion characteristics of alcohol-vegetable oil-diesel microemulsion fuels

ABSTRACT Biofuels are being considered as alternatives to fossil-based fuels due to depletion of petroleum-based reserves and pollutant emission concerns. Vegetable oils and bioalcohols have proven to be viable alternative fuels both with and without engine modification. However, high viscosity and low energy content are long-term operational problems with vegetable oils and bioalcohols, respectively. Therefore, vegetable oil-based microemulsification is being evaluated as a method to reduce the high viscosity of vegetable oils and enhance the miscibility of alcohol and oil phases. Studies have shown that microemulsification with different alcohols lead to varying fuel properties depending on their structure. The overall goal of this study was to formulate microemulsion fuels with single and mixed alcohol systems by determining the effects of water content, alcohol branching structure and carbon chain length on phase behaviors, fuel properties, and emission characteristics. It was found that microemulsion fuels using certain alcohols displayed favorable stability, properties, and emission characteristics. Flames of fuels with linear short-chain-length alcohols had larger near-burner blue regions and lower CO and soot emissions indicating the occurrence of more complete combustion. In addition to alcohol effects, the effect of vegetable oils, surfactants, and additives on emission characteristics were insightful in pursuit of appropriate microemulsion fuels as cleaner burning alternatives to both No.2 diesel and canola biodiesel.

Pilot Scale Study of Vegetable Oil Extraction by Surfactant-Assisted Aqueous Extraction Process

A number of aqueous extraction processes (AEP) have been studied as substitutes for hexane in oilseed extraction. In our previous batch-scale work, we have shown that the aqueous surfactant-based method could effectively extract up to 95% peanut and canola oils at 25°C. The goal of this work is to perform a semi-continuous pilot-scale study of the aqueous surfactant-based method for peanut and canola oil extraction. Two extraction strategies were evaluated including (1) a single extraction stage by aqueous surfactant solution and (2) two extraction stages, consisting of one aqueous surfactant wash and one de-ionized water wash. At optimum conditions, 90.6% and 88.1% oil extraction efficiencies of peanut and canola oil, respectively, were achieved in a single-stage extraction, while 94.5% and 92.6% were achieved in the two-stage extraction. At the highest solid/liquid centrifuge speed, the moisture level in the extracted meal was 48%. At the optimum liquid/liquid centrifuge condition, more than 90% of the oil was recovered as free oil from the extracted-oil and surfactant-wash mixture and 39–44% of the oil was recovered from the extracted oil and DI wash mixture. Total free oil recovered after the two-stage extraction was 87.1% and 85.6% for peanut and canola, respectively.

Colloid‐Enhanced Ultrafiltration of Chlorophenols in Wastewater: Part V. Simultaneous Removal of a Chlorophenol and a Metal Ion

Abstract Polyelectrolyte micellar‐enhanced ultrafiltration (PE‐MEUF) is a separation process to remove target solutes from water using a mixture of a surfactant and an oppositely charged polyelectrolyte as a colloid. An organic solute and a metal cation can simultaneously associate with the colloid, which is subsequently ultrafiltered from solution. An organic solute solubilizes in the surfactant micelle‐like aggregates whereas an inorganic cation binds onto the oppositely charged polyion chains. The solution is then passed through the membrane having pore sizes small enough to block the passage of the surfactant‐polymer aggregates. In this work, PE‐MEUF has been applied to mixtures containing dichlorophenol (DCP) and magnesium ion (Mg2+), using cetylpyridinium chloride (CPC) and sodium poly(styrenesulfonate) (PSS) mixtures. It was observed that the presence of Mg2+ does not affect DCP rejection. The [CPC] to [PSS] ratio and colloid concentration have a significant effect on both DCP and Mg2+ rejections. Increased ionic strength from added salt increases the gel point (colloid concentration at which flux is zero). The viscosity of the colloid solution is inversely related to the gel point.