Igepal CA-720 Research Articles

CO2 adsorption of MSU-2 synthesized by using nonionic polyethyleneoxide (PEO)-based surfactants

Adsorption technology is a well-established technology for CO2 removal. MSU-2 mesoporous silica appears to be very potential adsorbent for efficient CO2 gas adsorption due to its three-dimensional (3D) wormhole framework structures that are highly interconnected which is able to minimize the diffusion resistance of CO2. So far, there is no previous study reported on the CO2 adsorption of MSU-2. Thus, the current study focuses on the investigation on the synthesis of MSU-2 by using different surfactants (Triton X-100, Igepal CA-720 or Tergitol NP-9) and followed by the CO2 adsorption studies on the synthesized MSU-2. The morphology, crystallinity, functional groups, pore characteristics and pore structure of the MSU-2 synthesized were investigated. FESEM images showed that MSU-2 synthesized by using Igepal CA-720 possessed the most uniform and defined microspherical morphology compared to the MSU-2 synthesized by using the other surfactants. Besides, the MSU-2 synthesized by using Igepal CA-720 displayed the highest BET surface area of 938 m2/g and CO2 adsorption capacity of 0.57 mmol/g compared to the other MSU-2 samples. The obtained results showed that Igepal CA-720 is the most suitable surfactant for MSU-2 synthesis compared to the other surfactants in the current study.

Viscosity and Density of Binary Mixtures of Ethanol + Igepal (CO-520, CO-630, CO-720, and CA-720)

Surfactants are widely used for academic and industrial purposes. For this reason, thermodynamic and physical properties of surfactant and cosurfactant mixtures can provide important information about the nature of the molecular interactions present. In this work, volumetric and transport data of surfactant binary mixtures of the ethanol + Igepal series (Igepal CO-520, Igepal CO-630, Igepal CO-720, and Igepal CA-720) were determined experimentally within a range of temperature of T = 293.15–323.15 K, at atmospheric pressure. From these data, the following derivative properties have been calculated: the excess molar volume, viscosity deviation, and coefficient of thermal expansion. All of these mixtures showed that attractive intermolecular forces are dominant.

Biomass and chemical amendments for enhanced phytoremediation of mixed contaminated soils

Pot experiments were conducted to investigate the impact of biomass amendments (biochar, compost and nutrient solution) and chemical amendments (Ethylenediaminetetraacetic acid (EDTA) and Igepal CA-720) on the phytoremediation of soil co-contaminated with organic and metal contaminants by Helianthus annuus (sunflower) and Avena sativa (oat plant). Mixed contaminated soil was prepared by mixing clean soil with naphthalene, phenanthrene, lead (Pb), cadmium (Cd), and chromium (Cr). To study the biomass amendments, soil was amended with biochar, compost, or a nutrient solution. To study chemical amendments, plants raised in contaminated soils were amended with a solution of EDTA, Igepal CA-720 or both. The combination of biomass and chemical amendments were studied by treating composted soil with either EDTA or Igepal CA-720. The results showed that the biochar and compost amendments improved the growth characteristics and biomass of the plants. Growth improvement was best observed for sunflower plants in composted soil. Average maximum plant height of sunflower in contaminated soil was increased by 115% with the addition of compost. Cd and Pb removal was best in the presence of biochar and compost amendments, but Cr removal was unaffected by the use of amendments. The best removal rate was observed for Pb by oat plant in compost amended soil, with average final Pb concentration decreased by 57.8% with the addition of compost to soil. Nutrient solution amendment did not improve the removal of the metal contamination from the soil. The overall growth and biomass were less for plants grown in soil that was treated with chemical amendments. A combination of compost and chemical amendments also did not provide positive results on the plant growth or contaminant dissipation. Polycyclic aromatic hydrocarbon (PAH) degradation improved in the presence of all of the amendments studied. The results suggest that biochar and compost amendments can improve the plant growth characteristics and enhance phytoremediation of mixed contaminated soils.

Surfactant and oxidant enhanced electrokinetic remediation of a PCBs polluted soil

To remediate polychlorinated biphenyls (PCBs) polluted soils is a big challenge due to the high toxicity, persistence and hydrophobicity of PCBs. Traditional remediation techniques such as landfilling, incineration, heat adsorption and biodegradation have their different application conditions, while electrokinetics (EK) is an alternative choice to remediate PCBs polluted soils in low permeable soil. In this study, a PCBs polluted soil sampled from a landfill was selected as a typical soil, and Igepal CA-720 and persulfate were respectively selected as surfactant and oxidant for enhanced EK remediation of this soil. Batch experiments showed that 2% of Igepal CA-720 and 20% of persulfate were the optimum dosage for PCBs extraction and oxidation from the polluted soil. During the EK, Igepal CA-720 and persulfate were added in the anode and cathode reservoirs, respectively, and zero-valent iron was used as the activator of persulfate. The results showed that Igepal CA-720 partially solubilized soil PCBs and caused PCBs migration towards cathode, while persulfate was successfully delivered from cathode towards anode by EK. The highest degradation rate of PCBs was 38.0% in the treatment using Igepal CA-720 and persulfate in the absence of activator, which is ascribed that zero-valent iron, added in the cathode reservoir, consumed most of persulfate and inhibited its transport into the cell.

Enhanced Soil Flushing for Simultaneous Removal of PAHs and Heavy Metals from Industrial Contaminated Soil

Polycyclic aromatic hydrocarbons (PAHs) and heavy metals are environmental concerns and must be removed to acceptable levels. This paper evaluates different flushing agents to enhance the remediation of soil contaminated with PAHs and heavy metals at a former manufactured gas plant site. Four flushing column tests at a constant hydraulic gradient of 1.2 were conducted using four different flushing agents, which included deionized water, chelant (0.2 M EDTA), surfactant (5% Igepal CA-720), and cyclodextrin (10% hydroxypropyl-β-cyclodextrin or HPCD). Additional column tests using Igepal and HPCD at a lower hydraulic gradient of 0.2 were con- ducted to investigate the effects of rate-limited desorption or solubilization of PAHs. The results showed that the EDTA produced the maxi- mum metal removal from the soil compared with deionized water, Igepal, and HPCD under different hydraulic gradient conditions. The 0.2 M EDTA flushing solution removed approximately 25-75% of the toxic heavy metals found in the soil. None of the PAHs were removed from the soil when deionized water and EDTA were the flushing solutions. The PAHs removal efficiencies in the Igepal and HPCD systems decreased as the hydraulic gradient decreased. However, the surfactant-enhanced systems were more efficient in removing PAHs from the soil than the HPCD systems under high- and low-hydraulic gradients. The results also demonstrated that the removal of PAHs in surfactant-enhanced systems depended upon the micelles formation, whereas in the HPCD-enhanced systems, it depended upon the ster- ioselective diffusion of the PAHs to the nonpolar cavity of the HPCD. Overall, this study showed that the contaminant removal in soil flushing systems depends on the flushing solution affinity and selectivity toward the target contaminant and the existing hydraulic gradient condition. DOI: 10.1061/(ASCE)HZ.1944-8376.0000076. © 2011 American Society of Civil Engineers. CE Database subject headings: Soil pollution; Soil treatment; Remediation; Hydrocarbons; Heavy metals. Author keywords: Soil flushing; Remediation; Polycyclic aromatic hydrocarbons; Heavy metals.

Integrated electrokinetic-soil flushing to remove mixed organic and metal contaminants

The integrated use of hydraulic flushing and electrokinetic treatment was investigated for the remediation of silty sand contaminated by both PAHs and heavy metals. The soil was collected from a polluted former manufactured gas plant (MGP). Four bench-scale experiments were conducted to analyze the ability of the combined hydraulic flushing and the electrokinetic treatment for the simultaneous removal of PAHs and heavy metals. Sequential flushing with ethylenediaminetetraacetic acid (EDTA) or Igepal CA-720 were tested with or without the simultaneous application of a low intensity direct electric field (1 VDC cm−1). The best results were obtained with 0.2 M EDTA flushing in two stages (without and with voltage gradient, 1 VDC cm−1), followed by 5% Igepal flushing in two stages (without and with 1 VDC cm−1). Heavy metals were removed mainly during the EDTA flushing, with removal efficiencies of about 60% for Zn, 80% for Pb, and 30% for Cu. During Igepal flushing, no heavy metals were removed, but PAHs were removed, including 40% phenanthrene, 30% pyrene, and 20% benzo[a]pyrene. Overall, this study showed that a carefully designed sequential hydraulic flushing scheme with selected chelant and surfactant is needed for the removal of both heavy metals and PAHs from MGP silty sands. Combining electrokinetics with hydraulic flushing may not necessarily improve contaminant removal from such soils.

Surfactant-enhanced Electrokinetic Remediation of Mixed Contamination in Low Permeability Soil

Thousands of sites are contaminated with both heavy metals and organic compounds and these sites pose a major threat to the environment. Very few technologies, such as soil washing/flushing and stabilization/solidification, are available to remediate these sites; however, all these technologies are ineffective under low permeability and heterogeneous soil conditions. Previous studies have shown that electrokinetic remediation has potential to remove heavy metals and organic compounds when they exist individually in clayey soils. In the present study, the feasibility of using surfactants in electrokinetic remediation was evaluated to remove the PAHs in the presence of heavy metals from clayey soils. Kaolin was selected as a model clayey soil and it was spiked with phenanthrene and nickel at a concentration of 500 mg/kg-dry each to simulate typical mixed contamination. Bench-scale electrokinetic tests were performed using deionized water and two different surfactants, Igepal CA-720 and Tween 80, at 3% and 5% (in weight) each at the anode. These solutions at the anode were circulated and were buffered with 0.01 M NaOH to maintain neutral pH conditions. A periodic voltage gradient of 2 V/cm (with 5 days on and 2 days off cycles) was applied for all the tests. There was a significant migration of phenanthrene towards cathode in all the tests. Among all the extracting solutions used, complete removal of phenanthrene was observed using 5% Igepal CA-720. In case of Tween 80, the low electroosmotic flow limited the delivery of Tween 80 into the soil and therefore, limiting the phenanthrene solubilization and transport. It was observed that solubilization, electroosmotic flow, and concentration of the extracting solution are the critical factors that contribute to the removal of phenanthrene. Nickel electromigrated as cation towards the cathode and precipitated in the soil near the cathode due to high pH in all tests. Overall, nickel migration pattern was not affected by the presence of phenanthrene and the extracting solutions used in this study.

Extractants for the Removal of Mixed Contaminants from Soils

The development of improved and effective remediation technologies for soils contaminated by heavy metals as well as polycyclic aromatic hydrocarbons (PAHs) has emerged as a significant environmental priority. One technology that appears to have considerable promise is the ex-situ soil washing that involves the use of extracting agents such as surfactants, cosolvents, cyclodextrins, chelants, and weak acids. This study investigates the use of various single and sequential flushing schemes using different extracting agents (two surfactants, two cosolvents, two cyclodextrins, two chelants, and phosphoric acid and six organic acids) for the simultaneous removal of PAHs and metals from three different soils. Specifically, this study examines the effectiveness of different extractants on the removal of phenanthrene (representative PAH) and nickel, lead, and zinc (representative heavy metals) from the soils and evaluates the optimum composition of extractants in sequential flushing schemes. Soils used in this study were artificially spiked kaolin soil (a representative clayey soil with negligible organic content), Soil A collected from a former manufactured gas plant (MGP) site dominated by sand and high organic content, and Soil D collected from a different MGP site having high clay and low organic contents. Batch experiments with a single extraction step using surfactants showed that the removal of phenanthrene varied from 4.9% to 52% for kaolin, 40% to 100% for Soil A, and 21% to 72.6% for Soil D. 1M phosphoric acid and 1M citric acid were found to be effective for the removal of the three heavy metals from all soils. Sequential extraction schemes were designed and investigated for the simultaneous removal of phenanthrene and metals from all the soils. Results showed that 5% Tween 80 followed by 1M citric acid or 1M citric acid followed by 5% Igepal CA-720 schemes have potential for the removal of both phenanthrene and nickel from kaolin soil. However, 5% Tween 80 followed by 1M citric acid scheme or 0.2M EDTA followed by 5%Tween 80 scheme showed maximum removal of phenanthrene, lead, and zinc from Soil A and Soil D. Overall this study demonstrates that the removal of both heavy metals and PAHs from soils can be accomplished by developing a sequential flushing scheme based on specific site soil composition.

Comparison of Extractants for Removal of Lead, Zinc, and Phenanthrene from Manufactured Gas Plant Field Soil

Polycyclic aromatic hydrocarbons PAHs and heavy metals found at former manufactured gas plant MGP sites are of major environmental concern. An investigation is made into evaluating the capability of various extractants including surfactants, cosolvents, chelating agents, acids, and cyclodextrins for removing phenanthrene, lead, and zinc from a contaminated MGP soil. The determination of the most promising extracting solutions is critical for the development of effective treatment technologies such as soil washing/flushing and electrokinetic remediation. MGP contaminated soil was silty sand with 11% organic matter containing higher levels of phenanthrene and two heavy metals lead and zinc. Several batch tests were conducted using the soil with different extracting solutions at various concentrations to enhance the removal efficiency and to optimize the concentration of each extractant. The test results showed that both surfactants Igepal CA-720 and Tween 80 at a wide range of concentrations were effective for the removal of phenantherene from the soil. Only selective cosolvents and cyclodextrins n-butylamine and HPCD at higher concentrations were found to be effective in the solubilization of phenanthrene. Selective acids citric acid and phosphoric acid were found to be effective in the removal of heavy metals, while chelating agents EDTA and DTPA resulted in a moderate heavy metal removal. Overall, none of the selected extractants removed both heavy metals and PAHs; therefore, sequential extraction schemes using the selected extractants were investigated. The sequential use of 5% Tween 80 followed by 1 M citric acid was found to remove over 90% phenanthrene and over 70% lead and nickel each from the MGP soil.

PAH removal from Black Sludge from Aluminium Industry by Flotation using Non-ionic Surfactants

The valorization of black sludge is an environmental problem of the aluminium industry because of Polycyclic Aromatic Hydrocarbon (PAH), fluoride and alumina contents. A soil washing operated in a cell flotation with non-ionic surfactants (Brij 35, Igepal CA-720, Triton X-100, Tween 80) at different concentrations has been tested in order to remove the PAH (benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(j)fluoranthene, benzo(k)fluoranthene, fluoranthene) detected in black sludge. The Tween 80 at 0.5% gave the best results with PAH removal rates between 35 and 50%. These percentages remain low due to the presence in large quantity of fine solid particles (45%) in the PAH concentrate produced by the flotation process. The substitution of the cell flotation by a column flotation allowed the reduction of this problem. Thus, the PAH removal rates reached 60%. This removal yield has been obtained with the lowest wash water flow-rate (150 ml min−1) and pulp total solids (10% p p−1) tested.

Electrokinetic Remediation of Contaminated Dredged Sediment

Abstract This paper investigates the feasibility of electrokinetic remediation of contaminated sediment at Indiana Harbor, Indiana. The sediment is a fine-grained material with high moisture content of 78 % and high organic content of 19 % and it is contaminated with a wide range of polycyclic aromatic hydrocarbons (PAHs) and heavy metals. Four bench-scale electrokinetic experiments were conducted at 2.0 VDC/cm of constant voltage gradient using two surfactants (5 % Igepal CA-720 and 3 % Tween 80), a cosolvent (20 % n-butylamine), and a cyclodextrin (10 % HP-β-CD) as flushing solutions for the solubilization/desorption of PAHs. The mobility and removal of heavy metals was also investigated while flushing these solutions. The experimental results show that 20 % n-butylamine and 5 % Igepal 720 systems are effective for the partial solubilization of the PAHs in the sediments; however, both 3 % Tween 80 and 10 % HP-β-CD systems are found to be ineffective for desorption/solubilization of PAHs in the sediment. None of the selected flushing agents is found to be effective for the removal of heavy metals from the contaminated sediment. The low removal of PAHs and heavy metals is attributed to the high organic content and high acid buffering capacity of the sediment.

Enhanced electrokinetic remediation of contaminated manufactured gas plant soil

This paper evaluates different flushing agents to enhance the efficiency of electrokinetic remediation of a manufactured gas plant (MGP) soil contaminated with polycyclic aromatic hydrocarbons (PAHs) and heavy metals. Because of high concentrations, PAHs were of environmental concern and required to be removed to acceptable levels. Four flushing agents, which included two surfactants (3% Tween 80, and 5% Igepal CA-720), one cosolvent (20% n-Butylamine) and one cyclodextrin (10% hydroxypropyl-β-cyclodextrin or HPCD), were examined to enhance the solubilization of PAHs in the soil. Four electrokinetic experiments were conducted at 2.0 VDC/cm voltage gradient and 1.4 hydraulic gradient in order to assess the effectiveness of these flushing solutions for the removal of PAHs. Variables measured during the application of electric potential were electric current, electroosmotic flow, and contaminant removal from the soil. After the completion of each test, the soil was further examined for moisture content, pH, redox potential, electrical conductivity, and residual contaminant distribution. It is found that cosolvent increased the soil pH, while the surfactants and HPCD did not induce substantial change in the soil pH. The current densities fluctuated with time for all tests and remained less than 1 mA/cm 2. The current density for the test conducted with cosolvent was higher as compared to the tests conducted with surfactants and HPCD. Electroosmotic flow was the maximum with the cosolvent, while the lowest flow was observed with Tween 80 surfactant. Overall, Igepal CA-720 surfactant yielded the highest removal efficiency due to partial solubilization of PAHs, causing some PAHs to migrate towards the cathode. Heavy metals are found to be strongly adsorbed/ precipitated and showed negligible migration behavior in all the tests. Based on the contaminant mass remaining in the soil, it is apparent that further optimization of the electrokinetic system is required to improve PAH removal efficiency for the MGP soil.

Nickel Catalysts Supported on MgO/Smectite-Type Nanocomposites for Methane Reforming

AbstractMgO-clay nanocomposites were prepared from a synthetic smectite-type clay, TS, using three different non-ionic surfactants (Igepal CA-720, Brij 30 and Brij 56) and the resulting clay nanocomposites were impregnated with Ni for the methane reforming reaction with carbon dioxide to synthesis gas. A Ni/TS catalyst was also prepared for comparison. The prepared supports and catalysts were characterized by X-ray diffraction, X-ray fluorescence, thermogravimetric analysis and N2 adsorption/desorption isotherms. The thermal stability, pore structure and the surface area strongly influence the catalytic behavior of the catalysts. The methane conversions (at 700°C for 4 h) were 91, 95 and 97% for Ni/TSIGE, Ni/TSBR30 and Ni/TSBR56, respectively, indicating that the surface properties and the catalytic performance of the resulting solids slightly improved as the polyethylene oxide number of the surfactant increased. A reduced conversion (10%) and a rapid deactivation was observed in the Ni/TS catalyst, attributed to its Na content and low thermal stability, which led to sintering and coke deposition.

Surfactant-enhanced electrokinetic remediation of polycyclic aromatic hydrocarbons in heterogeneous subsurface environments

Polycyclic aromatic hydrocarbon (PAH) contamination exists at numerous sites and poses a substantial risk to public health and the environment. Electrokinetic remediation technology has the potential to treat PAH-contaminated soils, but the effect of soil heterogeneities such as layers, lenses, and mixtures of different soils on the electrokinetic process has not been adequately studied. This study evaluates surfactant-enhanced electrokinetic remediation under heterogeneous soil conditions. A series of bench-scale experiments was conducted using two soils (sand and kaolin) spiked with a representative PAH compound (phenanthrene) in a two-dimensional electrokinetic test apparatus under various layered, lens, or mixed soil configurations. In addition, the homogeneous sand and kaolin soils were each tested alone for comparison purposes. All the experiments employed the same nonionic surfactant (5% Igepal CA-720) flushing solution and a low (0.05) hydraulic gradient. The results showed that the surfactant flushing under the low hydraulic gradient alone was sufficient for complete removal of the contaminant from the homogeneous sand profile, whereas the electroosmotic flow generated by the application of a DC 2.0 V/cm electric potential in a periodic mode considerably enhanced the removal efficiency for the homogeneous and heterogeneous soil profiles containing kaolin. The voltage gradient varied spatially and temporally through the soil profiles and affected the electroosmotic flow and contaminant removal. Key words: clays, electrokinetic remediation, electroosmosis, flushing, heterogeneity, polycyclic aromatic hydrocarbons (PAHs), phenanthrene, soils, sorption, solubilization, surfactants.

Effect of different extraction agents on metal and organic contaminant removal from a field soil

This paper presents an evaluation of different extracting solutions for the removal of phenanthrene, lead and zinc from a contaminated soil obtained from a former manufactured gas plant site. The field soil contained 50%–88% sand, 11%–35% fines, 2.7%–3.7% organic matter and high concentrations of phenanthrene (260 mg/kg), lead (50.6 mg/kg) and zinc (84.4 mg/kg). A series of batch extraction experiments were conducted using the field soil with different extracting solutions at various concentrations to investigate the removal efficiency and to optimize the concentration of each extractant. The results showed that removal efficiencies of different flushing systems were significantly influenced by their affinity and selectivity for the contaminants in the soil matrix. Non-ionic surfactants (Igepal CA720 and Tween 80) were found to be effective in removing phenanthrene, but they were ineffective in removing lead and zinc. Chelating agents (ethylenediamine tetra acetic acid, EDTA and diethylene triamine penta acetic acid, DTPA) and selected acids were effective in removing lead and zinc, but they were ineffective for the phenanthrene removal. Co-solvents and cyclodextrins were not effective for removal of any of the contaminants. A sequential use of the 0.2 M EDTA followed by 5% Tween 80 or 5% Tween 80 followed by 1 M citric acid was found to be effective for the removal of lead, zinc, and phenanthrene. Overall, it can be concluded that sequential use of different extracting solutions is required for the removal of both heavy metals and organics from field contaminated silty sand soils.

Direct Synthesis of Hybrid Organic−Inorganic Nanoporous Silica Microspheres. 1. Effect of Temperature and Organosilane Loading on the Nano- and Micro-Structure of Mercaptopropyl-Functionalized MSU Silica

The preparation of a series of organically functionalized wormhole-motif microspherical MSU-X silicas mesostructures was achieved by a direct synthesis process involving the addition of tetraethoxysilane (TEOS) and 3-mercaptopropyltrimethoxysilane (MPTMS) to mildly acidified solutions of a structure-directing nonionic surfactant (Igepal CA-720), followed by fluoride-mediated hydrolysis/cross-linking and surfactant extraction. The influence of organosilane content (MPTMS/TEOS ratio) and synthesis temperature on the framework order, pore structure, and particle size of the resulting mesostructures was investigated. The lattice spacings, pore volumes, and pore diameters were found to systematically increase as a function of increasing synthesis temperature. Although very poorly ordered and microporous when prepared at lower synthesis temperatures, the framework ordering and pore channel diameters of the microspheres dramatically improved when these were synthesized at temperatures above 40−45 °C. Moreover, increasing the synthesis temperature reduced the average particle sizes of the microspheres, although a sudden swelling of the particle sizes was observed in the threshold temperature zone where improved framework order and mesoporosity in the microspheres was evidenced. Incorporation of organic functional groups (MPTMS) inside the structures appeared to have little influence on the structure and morphology of the mesostructures, save for slight lattice and pore diameter contractions upon increasing organosilane group loading. By systematically varying the organosilane content and the synthesis temperature of the microspheres, functional MSU-X materials with accurately fine-tuned pore dimensions and particle diameters could therefore be obtained.

Soil Washing Feasibility at a Manufacturing Gas Plant Site

Bench-scale treatability tests were carried out in order to evaluate performances of “physical” soil washing (particle size classification aimed at “concentrating” contamination in the fine fraction of the soil) and of a surfactant-aided soil-washing process on a brownfield soil, contaminated by high-molecular-weight Polycyclic Aromatic Hydrocarbons (PAHs). In the first case, soil was classified by wet particle separation using water, whereas it was extracted by water + surfactant in the second case. The chemical agent was selected among non-ionic synthetic and anionic biogenic surfactants (Triton X-100, Igepal CA-720, Brij-30, JBR 325), evaluating the kinetics of the desorption process and the extraction efficiency for different time of contact with soil. Surfactant concentration was selected by evaluating the extraction efficiency at the optimal time of contact. A surfactant-aided soil-washing process was tested, where soil was sequentially treated by fresh soil-washing solution (water + surfactant), and soil-washing solution was recycled for other contaminated soil. Transfer efficiency of PAHs and recovery of surfactant solution were evaluated

Fenton Oxidation of Polycyclic Aromatic Hydrocarbons After Surfactant-Enhanced Soil Washing

The feasibility of using a combination of two well-studied technologies - soil washing and Fenton oxidation - to remove polycyclic aromatic hydrocarbons (PAH) from soil and subsequently destroy them in the resulting waste water solution was investigated. Three well-characterized New Jersey soils, representing a wide range of organic carbon content, were artificially contaminated with a mixture of anthracene, phenanthrene, and fluoranthene to simulate PAH-contaminated field soil. Batch laboratory-scale surfactant-enhanced soil washing was used to remove PAH from these soils. Two nonionic octylphenyl ethoxylate-type surfactants - Triton X-100 and Igepal CA-720 - were employed. PAH concentration in wash solution containing 1% surfactant was increased by over an order of magnitude above the level possible with water alone. The resulting solutions were treated with Fenton's reagent (H2O2 plus Fe2+) to destroy PAH in solution. Greater than 99% of PAH parent material was destroyed in the Triton X-100 wash soluti...

Effects of surfactants on extraction of phenanthrene in spiked sand

Problems associated with polynuclear aromatic hydrocarbon (PAH) contaminated site in environmental media have received increasing attention. To resolve such problems, innovative in situ methods are urgently required. This work investigated the feasibility of using surfactants to extract phenanthrene on spiked sand in a batch system. Phenanthrene was spiked into Ottawa sand to simulate contaminated soil. Six surfactants, Brij 30 (BR), Triton X-100 (TR), Tergitol NP-10 (TE), Igepal CA-720 (IG), sodium dodecyl sulfate (SDS) and hexadecyl trimethyl ammonium bromide (HTAB) were used. Adjusting the extraction time, mixing speed and surfactant concentration yielded the optimum extracting conditions. The concentration of phenanthrene was identified with HPLC. Under the experimental conditions, results indicated that those surfactants were highly promising on site remediation since the residual phenanthrene concentration was effectively reduced. The optimum operating conditions were obtained at 30 min, 125 rpm and surfactant concentrations in 4%.

Effect of nonionic surfactants on naphthalene dissolution and biodegradation.

The effect of six nonionic surfactants, Igepal CA-720, Tergitol NPX, Triton X-100, PLE4, PLE10, and PLE23, on the dissolution rate of solid naphthalene was studied in stirred batch reactors. Results showed increased mass-transfer rates with increased surfactant concentrations up to 10 kg m-3. Dissolution experiments were adequatly described by a mechanistic mass-transfer model. Partitioning of naphthalene into the micelles and the diffusion coefficients of the micelles affected the dissolution rate most significantly. Combined dissolution and biodegradation experiments with Triton X-100 or PLE10 with naphthalene showed that the biomass-formation rate of Pseudomonas 8909N (DSM No. 11634) increased concomitantly with the mass-transfer rate under naphthalene-dissolution limited conditions up to surfactant concentrations of 6 kg m-3.