Biodegradable Surfactants Research Articles

FEASIBILITY OF IN SITU NAPL-CONTAMINATED AQUIFER BIOREMEDIATION BY BIODEGRADABLE NUTRIENT–SURFACTANT MIX

Entrapped non-aqueous liquid phase (NAPL) pollutants (e.g., fuels) constitute one of the biggest current problems in the bioremediation efforts of contaminated soil and aquifers worldwide. On site, in situ surfactant-enhanced bioremediation, in the presence of sufficient nutrients and dissolved oxygen, has the potential of becoming the remediation method of choice in terms of both technological and economical feasibility. This approach was applied in our lab-scale column-based flow system with the aid of which an optimized, below CMC, of biodegradable surfactant-nutrient surfactant mix has been established for the best solubilization/mobilization of NAPL (hexane, toluene, kerosene and their mixtures as “representatives”) in sandy matrix. For kerosene, the highest f values (the enhancement factors) were obtained for the systems containing either the amphoteric cocoamphodiacetate or the anionic linear dodecylbenzene sulfonate (0.1–0.3 g/L) with one or both the nutrient-surfactants L and B (0.05 g/L).

A laboratory study of surfactant flushing of DNAPL in the presence of macroemulsion.

Computed tomography (CT) monitored experiments are conducted in a three-dimensional water-saturated sandpack to evaluate the performance of a biodegradable surfactant (Glucopon-425N) in recovering a residually trapped dense nonaqueous phase liquid (DNAPL) tetrachloroethylene (PCE) from two sandpacks. Effects of flow rate, surfactant concentration, and pore size on the remediation process are evaluated. Axial variation in porosity of a sandpack has significant effect on the residual distribution of DNAPL in the sandpack and its subsequent recovery. DNAPL is recovered in two stages in general: mobilization followed by macroemulsion-solubilization. Mobilized DNAPL is recovered as a free-phase for all the experiments in the 30-mesh sandpack and only limited mobilization was observed in the 50-mesh sandpack. The dominant mechanism of recovery is macroemulsion flow (accounts for 46-86% of solubilized-emulsified PCE) in both the sands which leads to much higher PCE effluent concentration than the solubility limit as determined in batch solubilization studies. The effluent PCE concentration in the later stage depends on surfactant concentration but not on surfactant flow rate or pore size.

Enhanced biodegradation of polycyclic aromatic hydrocarbons using nonionic surfactants in soil slurry

The effect of nonionic surfactants on the solubility and biodegradation of polycyclic aromatic hydrocarbons (PAHs) in the aqueous phase and in the soil slurry phase, as well as the fate of these surfactants, were investigated. The PAH solubility was linearly proportional to the surfactant concentration when above the critical micelle concentration (CMC), and increased as the hydrophile–lipophile balance (HLB) value decreased. Substantial amounts of the sorbed phenanthrene in the soil particles were desorbed by non-ionic surfactants into the liquid phase when the ratio of soil to water was 1:10 (g/ml). Brij 30 was the most biodegradable surfactant tested, showed no substrate inhibition up to a concentration of 1.5 g/l, and was definitely used as a C source by the bacteria. Naphthalene and phenanthrene were completely degraded by phenanthrene-acclimatised cultures within 60 h, but a substantial amount of naphthalene was lost due to volatilization. The limiting step in the soil slurry bioremediation was bioavailability by the micro-organisms for the sand slurry and mass transfer from a solid to aqueous phase in the clay slurry.

Large Scale Synthesis and Properties of the Novel Sucrose Aspartate Surfactants

ABSTRACT Sucrose aspartates were synthesised on kg-scales using a simple, high-yielding one-pot procedure from inexpensive sucrose, fatty amines and maleic anhydride and tested for their physical properties. Mostly being derived from renewable resources, these novel biodegradable surfactants provided favourable application properties.

Treatability Testing of Intrinsic Bioremediation, Biostimulation, And Bioaugmentation of Diesel-oil Contaminated Soil At 5 ° C

Abstract To support the remediation design for a diesel-oil pipeline break near a remote railway river crossing near the British Columbia and Alaska border, a treatability test was designed to assess the in-situ bioremediation potential under four conditions of soil amendments at 5 ° C. The four conditions were:intrinsic bioremediation, where the soil received only water;biostimulation with one application of slow-release fertilizer;bioaugmentation with one application of both fertilizer and a psychrotrophic (cold-adapted), hydrocarbon-degrading bacterial culture; andsurfactant enhanced bioavailability, where the soil received one application of fertilizer and treatment with a biodegradable surfactant solution. Tests were monitored by soil respiration and bacterial enumeration and total extractable hydrocarbon (TEH) content by GC/FID. After 40 days incubation under aerobic conditions, all tests showed significant reduction in diesel range (C7 - C30) THE contamination. The intrinsic control was least effective, but still showed 66% TEH reduction at 5 ° C. The biostimulated soil performed the best, allowing 86% TEH reduction. The bioaugmented soil and surfactant treated soil both allowed about 75% TEH reduction. The study concluded that simple biostimulation with slow-release fertilizers would be the most appropriate bioremediation approach for this site. Introduction A four-inch diameter petroleum pipeline, located adjacent to the rail tracks of the White Pass and Yukon Route Railroad, was broken by heavy equipment working in the area in October 1994. A significant quantity of Arctic diesel fuel leaked and immediate efforts were made to recover most of the product through the summer of 1995. Following site investigation in November 1995, a plume of diesel contamination was delineated in the gravelly cobbles and boulder fill supporting the railway bridge over the East Fork Skagway River. The plume had migrated downward through the fill to bedrock surface. Liquid product at the toe of the slope could discharge with shallow groundwater flow over ground surface into the river. The estimated 500 m3 of residual hydrocarboncontaminated fill supporting the railway bed required remediation to prevent continued contamination of the water passing through the contaminated area. Initial soil chemical and biological data indicated that active natural biodegradation of petroleum hydrocarbons may be occurring at the site, but appears limited by natural nutrient level and the indigenous bacterial population at the site. The gravelly soil near the toe of the slope contains between 1,000 and 5,000 mg/kg of total extractable hydrocarbons (TEH) and has an indigenous heterotrophic bacteria population of between 104 and 106 bacteria/ g of soil. Excavation of the slope and structural fill supporting the operating railway was not feasible; therefore, in-situ remediation options were considered. Because of the generally low volatility of some components of Arctic diesel and the lack of electrical power at the remote site, in-situ bioremediation was considered the most feasible option. To determine the optimal conditions for in-situ bioremediation of this hydrocarbon-contaminated soil, a laboratory-scale treatability study was carried out. Because of the cold climate near the Alaska-British Columbia border, it was imperative that the testing be performed at the expected ambient soil temperature of about 5 to 8 ° C.

Competitive Substrate Biodegradation during Surfactant-Enhanced Remediation

The impact of synthetic surfactants on the aqueous phase biodegradation of benzene, toluene, and p-xylene (BTpX) was studied using two anionic surfactants, sodium dodecyl sulfate (SDS) and sodium dodecyl benzene sulfonate (SDBS), and two nonionic surfactants, POE(20) sorbitan monooleate (T-maz-80) and octylphenolpoly(ethyleneoxy) ethanol (CA-620). Batch biodegradation experiments were performed to evaluate surfactant biodegradability using two different microbial cultures. Of the four surfactants used in this study, SDS and T-maz-80 were readily degraded by a microbial consortium obtained from an activated sludge treatment system, whereas only SDS was degraded by a microbial culture that was acclimated to BTpX. Biodegradation kinetic parameters associated with SDS and T-maz-80 degradation by the activated sludge consortium were estimated using respirometric data in conjunction with a nonlinear parameter estimation technique as μmax = 0.93 h−1, Ks = 96.18 mg/L and μmax = 0.41 h−1, Ks = 31.92 mg/L, respectively. When both BTpX and surfactant were present in the reactor along with BTpX-acclimated microorganisms, two distinct biodegradation patterns were seen. SDS was preferentially utilized inhibiting hydrocarbon biodegradation, whereas the other three surfactants had no impact on BTpX biodegradation. None of the four surfactants were toxic to the microbial cultures used in this study. Readily biodegradable surfactants are not very effective for subsurface remediation applications as they are rapidly consumed, and also because of their potential inhibitory effects on intrinsic hydrocarbon biodegradation. This greatly increases treatment costs as surfactant recovery and reuse are adversely affected.

Sucrose ester microemulsions

Sucrose esters are biodegradable surfactants that can be manufactured in various hydrophilic-lipophilic properties using different fatty acids varying in their lipophilic chain length. These surfactants are used in different industries including pharmaceutical, food processing, detergents, agricultural and others. Few number of works had been done using sucrose esters in microemulsions. In this review we tried to introduce the relevant works that enlighten the behavior of sucrose esters in phase diagrams prepared using different oils and medium chain alcohols. We hope that this review article can be an aid to those researchers interested in microemulsions based on sucrose esters and their applications.

Sucrose Ester Microemulsions

Sucrose esters are biodegradable surfactants that can be manufactured in various hydrophilic-lipophilic properties using different fatty acids varying in their lipophilic chain length. These surfactants are used in different industries including pharmaceutical, food processing, detergents, agricultural and others. Few number of works had been done using sucrose esters in microemulsions. In this review we tried to introduce the relevant works that enlighten the behavior of sucrose esters in phase diagrams prepared using different oils and medium chain alcohols. We hope that this review article can be an aid to those researchers interested in microemulsions based on sucrose esters and their applications.

Removal of Heavy Metals from Contaminated Soil and Sediments Using the Biosurfactant Surfactin

The feasibility of using a biodegradable surfactant, surfactin from Bacillus subtilis, for the removal of heavy metals from a contaminated soil (890 mg/kg zinc, 420 mg/kg copper, 12.6% oil and grease) and sediments (110 mg/kg copper, 3300 mg/kg zinc) was evaluated. Results showed that after one and five batch washings of the soil, 25 and 70% of the copper, 6 and 25% of the zinc, and 5 and 15% of the cadmium could be removed by 0.1% surfactin with 1% NaOH, respectively. From the sediment, 15% of the copper and 6% of the zinc could be removed after a single washing with 0.25% surfactin/1% NaOH. The geochemical speciation of the heavy metals among the exchangeable, oxide, carbonate, organic, and residual fractions was determined by selective sequential extraction procedure. For both matrices, the exchangeable fractions were minimal, while the carbonate and the oxide fractions accounted for over 90% of the zinc present and the organic fraction constituted over 70% of the copper. Results after washing indicated that surfactin with NaOH could remove copper from the organic fraction, zinc from the oxide, and cadmium from the carbonate fractions. The residual fraction remained untouched. These experiments indicate that the sequential extraction studies could be useful in designing soil-washing procedures.

Nanosized hydroxyapatite powders from microemulsions and emulsions stabilized by a biodegradable surfactant

Ultrafine hydroxyapatite powders have been successfully synthesized in inverse microemulsions and emulsions consisting of petroleum ether as the oil phase, 1.0 M CaCl 2 solution as the aqueous phase and biodegradable KB6ZA as the surfactant. The titration of 0.6 M (NH 4 ) 2 HPO 4 aqueous solution into the inverse microemulsion and emulsions containing 25.0 and 35.0 wt% aqueous phase, resulted in hydroxyapatite precursors that were nanometer sized and more or less spherical in morphology. However, they underwent a considerable degree of particle coarsening when calcined at 650 °C for 6 h. A nanocrystalline hydroxyapatite powder, which exhibited a dendritic agglomerate morphology, was synthesized in an oil-in-water emulsion containing 90.0 wt% aqueous phase. It shows an average particle size of 25 nm upon calcination at 650 °C for 6 h, as little particle coarsening and growth in crystallite size were observed at the calcination temperature. The inverse microemulsion- and emulsion-derived hydroxyapatites exhibit a degree of type B carbonate substitution, which cannot be eliminated by calcination in air at 650 °C.

Acute and sublethal effects of a non-ionic surfactant, Genapol OXD-080, on mosquitofish Gambusia holbrooki (Girard).

Application of the biodegradable non-ionic surfactant Genapol OXD-080, a fatty alcohol polyglycol ester, in rice paddies has been considered as a method to mitigate damage caused by the Louisiana red swamp crayfish, Procambarus clarkii, to rice crops. The damages are a consequence of crayfish digging activities. The acute and sublethal effects of Genapol on a non-target key species were examined to assess the potential risk of contaminating the irrigation channels following its application in the rice paddies. Mosquitofish, Gambusia holbrooki, due to its abundance in irrigation channels, and because it is a predator with an intermediate position in the food chain, was selected as the key non-target species. The LC50 value for Genapol to mosquitofish was 2.9 mg l-1, a value 17.2 times lower than the Genapol concentration needed to decrease crayfish digging activity (50 mg l-1). For sublethal tests, three biological parameters were considered in laboratory experiments with mosquitofish: respiratory metabolism, food (energetic) consumption, and clutch survival. A significant decrease in the resting metabolism of mosquitofish was observed, even when Genapol exposure concentrations were very low (e.g., 0.75 mg l-1). Thus, oxygen consumption rates of mosquitofish are strongly affected by to the presence of this surfactant in water. In contrast, mosquitofish food consumption and clutch survival seemed not to be affected by sub-lethal concentrations of Genapol. Yet, sub-lethal effect concentrations for mosquitofish are so much lower than the concentration necessary to decrease significantly crayfish activity, we conclude that there is a reasonable potential risk of damaging local mosquitofish populations if contamination of the irrigation channels with Genapol occurs.

Use of the yeast Hansenula polymorpha ( Pichia angusta) to remove contaminating sugars from ethyl β- d-fructofuranoside produced during sucrose ethanolysis catalysed by invertase

Alkyl glycosides are interesting intermediates for the production of biodegradable surfactants. Synthesis of ethyl β- d-fructofuranoside by invertase-catalysed ethanolysis of sucrose has been extensively reported in literature. However, this procedure yields mixtures of glucose, fructose, sucrose and ethyl β- d-fructofuranoside. Purification of ethyl β- d-fructofuranoside from such mixtures by chromatographic methods is laborious, difficult to scale up and requires organic solvents. The yeast Hansenula polymorpha grows rapidly on glucose, fructose and sucrose. Sucrose hydrolysis in this yeast is catalysed by an intracellular α-glucosidase (‘maltase’); consequently, H. polymorpha should be unable to hydrolyse ethyl β- d-fructofuranoside. Indeed, aerobic cultivation of H. polymorpha on sugar mixtures obtained by invertase-catalysed ethanolysis of sucrose resulted in the complete removal of contaminating sugars, leaving ethyl β- d-fructofuranoside as the sole organic compound in culture supernatants. Pure ethyl β- d-fructofuranoside was recovered from the supernatants by mixed-bed ion exchange chromatography with an 86% yield.

Enzymatic amidification for the synthesis of biodegradable surfactants: Synthesis of N-acylated hydroxylated amines

Glucamide surfactants can be obtained by reacting amino–sugar derivatives with fatty acids in the presence of lipase enzymes in organic media. Reactions are catalyzed with Lipozyme in hexane or with Novozym in 2-methyl-2-butanol as solvents. In hexane, the formation of a salt complex between the fatty acid and N-methyl-glucamine allows the efficient acylation of the amine. Fatty acid conversion is limited to 50% due to salt formation. In 2-methyl-2-butanol, conversion yield of the fatty acid up to 100% can be obtained by removing the water coproduct under reduced pressure. Acido–basic conditions allow the control of the reaction chemoselectivity. This reaction can also be completed using various amines and acyl donors.

Enhancing solubilization of sparingly soluble organic compounds by biosurfactants produced by Nocardia erythropolis

The goal of this research was to produce nontoxic, biodegradable surfactants from Nocardia erythropolis (American Type Culture Collection [ATCC] 4277) and to investigate their potential for enhancing the solubility of sparingly soluble organic compounds (SSOCs). After biosurfactants were harvested from the culture broth, SSOC removal capabilities from aqueous systems by micelles and monomers were determined. Nocardia erythropolis was grown in a 500‐mL batch reactor with n‐hexadecane as the sole carbon source. Surface tension of the mineral salts medium dropped from 64 dyne/cm to 41 dyne/cm within 24 hours after inoculation with an acclimated culture of N. erythropolis, indicating the production of appreciable quantities of surface‐active agents. The lowest surface tension value of 35.2 dyne/cm was reached in 4 days. Maximum production of surfactant was also observed at 4 days. Sparingly soluble organic compounds were partitioned into surfactant micelles that form when the surfactant concentration exceeds the critical micelle concentration. Sparingly soluble organic compound partitioning into micelles increased with decreasing SSOC solubility. The partition constants by micelles were 0.002 0, 0.008 6, and 0.041 2 L/mg for toluene, p‐xylene, and trimethylbenzene, respectively. The partitioning capacity of p‐xylene by the biosurfactants produced from N. erythropolis was an order of magnitude greater than that by the synthetic surfactant sodium dodecylsulfate (SDS).

Removal of Trichloroethylene in Presence and Absence of Surfactant

Because of the increasing use of surfactant, a study on the effect of a surfactant on the degradation of organic compound such as trichloroethylene (TCE), which is often detected in contaminated groundwaters, is needed. The objectives of this study were to determine biokinetic constant of TCE and to investigate the TCE degradation in presence and absence of a biodegradable nonionic surfactant, with phenol-oxidizing microorganisms. In a batch experiment, phenol provided a carbon and energy source to the phenol-oxidizing microorganisms that could produce more requisite enzyme capable of TCE degradation. The pseudo first-order rate constant (k) of TCE was found to be 0.0089 L mg-1 VS-day. More phenol was degraded in the absence of surfactant than in the presence of surfactant. The surfactant was also degraded by the phenol-oxidizing micrrorganisms. In the batch study, the addition of the surfactant (50 mg L-1) neither improved nor significantly hindered the TCE degradation.

Enzymatic Synthesis of Surfactants Via Amide Bonds

Non-ionic biodegradable surfactants can be obtained by reacting amino alditol derivatives with fatty acids in the presence of lipases in organic media. Such surfactants in contrast to ester bonds, containing an amide bond are stable under alkaline conditions. The efficient coupling of N-methyl-glucamine to oleic acid can be catalysed with Lipozyme in hexane or with Novozym in 2-methyl-2-butanol as solvents. In the first case, the acid/base ratio controls both kinetics and chemo-selectivity of the reaction. In the second case, the adoption of acid base conditions allow control of the chemo-selectivity of the reaction. This reaction can also be completed by using triglycerides or fatty acid esters as acyl donors, which opens the way to the valorization of plant oils for surfactant synthesis.

Laboratory evaluation of a biodegradable surfactant for In Situ soil flushing

Laboratory studies were performed to examine the removal of NAPL m‐xylene from porous media using a biodegradable 5% sodium lauroy/sarcosinate surfactant flushing solution (Hamposyl L‐30, Hampshire Chemical Corp., Nashua, NH). Vertical glass columns were packed with 0.6‐mm glass beads or washed sand and contaminated with m‐xylene. Columns were drained by gravity so that the media initially contained three phases: air, water, and m‐xylene. Removal of m‐xylene was primarily by enhanced solubilization. Recovery of 95% of residual m‐xylene from washed sand was obtained with an average of 43.2 pore volumes of surfactant solution, as opposed to an estimated 477 pore volumes required when flushing with water alone. Addition of surfactants caused decreases in interfacial tensions and therefore column dewatering that resulted in decreased flow rates through the unsaturated media. Effluent samples were acidified to induce phase separation via formation of water insoluble sarcosine acid, which was observed as a white waxy solid that contained 95.4% of the effluent m‐xylene in the solid phase. A biodegradable surfactant that, once used, can be separated from the effluent with the organic contaminant immobilized in the solid phase appears to be attractive for soil remediation purposes.

Die Nutzung nachwachsender Rohstoffe: Möglichkeiten und Grenzen

The quest for sustainable development of economically and ecologically attractive technologies is stimulating interest in better utilization of biomass and agricultural materials as renewable resources for chemicals, fuel, and polymers. In comparison to 'biodiesel' fuel, involving high energy consumption in biomass conversion, incineration of biomass, especially of agricultural wastes, represents the preferred route to energy production combined with reduced total carbon dioxide emission. Carbohydrates and plant oils are attractive renewable raw materials for the production of a wide range of chemicals, including pharmaceuticals and novel biodegradable surfactants. Plant cells are being converted into chemical reactors to facilitate exploitation of feedstocks such as fatty acids. Although price/performance ratio typical for commodity plastics are not met, biopolymers are being introduced as components of packaging and lightweight materials, e.g., natural-fiber-reinforced composites for automotive applications. Illustrated by selected examples, this overview highlights prospects and Iimitations of renewable resources and agricultural feedstocks in energy technology and chemical industry.

Environmental chemistry for a surfactant ecotoxicology study supports rapid degradation of C12-alkyl sulfate in a continuous-flow stream Mesocosm

Environmental chemistry is a vital part of ecotoxicology studies conducted in mesocosms. Quantification of exposure can be particularly challenging for biodegradable surfactants in once-through stream mesocosms like the Procter & Gamble Experimental Stream Facility (ESF). In the fall of 1991, a study was conducted with the anionic surfactant C12-alkyl sulfate (C12-AS). Analysis of chemical feed tank concentrates indicated that the in-stream concentrations should be very close to the nominal concentrations (26, 78, 233, 700, 2, 100 μg/L). However, measured concentrations were lower than expected. The concentrations at the head of the streams were 4 to 23% below nominal concentrations and there was an additional 14 to 33% decline in head to tail C12-AS concentrations. Total residence time in the streams is about 4.3 min. Because analytical losses had been minimized using individual sample recovery factors, it was concluded that these losses were due to rapid C12-AS biodegradation. The results of this analytical program are used to define the in-stream C12-AS concentrations to express subsequent community- and ecosystem-level no-observed-effect concentrations. In addition, the environmental chemistry program described will serve as the model for future programs in support of surfactant ecotoxicology studies conducted at the ESF.

A novel flow-through method for toxicity assessments usingCeriodaphnia dubia

Maintenance of chemical concentrations during toxicity tests is essential to determine the intrinsic toxicity of a material. For compounds that are sorptive, rapidly biodegraded, volatile or chemically labile, static and/or static renewal exposure strategies may result in large fluctuations in exposure concentrations over time, particularly for chronic tests. This article describes the development and adequacy of a novel flow-through chronic toxicity test method for the cladoceran Ceriodaphnia dubia, using a rapidly biodegradable surfactant, dodecyl alkyl sulfate (C12AS) as a model compound. Organisms were exposed to C12AS in polystyrene cups fitted with Nitex mesh on two opposing sides. Cups were placed in either plexiglass or glass flow-through channels. Alkyl sulfate solutions were delivered to the troughs via peristaltic pumps at one end and pumped through the individual test chambers in a linear fashion, exiting at the downstream end. Flow-through tests were conducted with both reconstituted and river water. Control mortality and reproduction met current U.S. Environmental Protection Agency criteria (less than 20% mortality and greater than 15 neonates/female). Three advantages of this system are (1) the method provides an advance over current Ceriodaphnia dubia chronic test methods for sorptive and labile compounds, (2) it is compact and portable, and (3) it is useful for other small aquatic organism tests. © 1996 by John Wiley & Sons, Inc.