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Penfold J, Thomas RK. Neutron reflection and the thermodynamics of the air-water interface. Phys Chem Chem Phys 2022; 24:8553-8577. [PMID: 35352746 DOI: 10.1039/d2cp00053a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
By means of isotopic substitution, measurements of the neutron reflectivity (NR) from a flat water surface generally give model independent measurements of the amount of a chosen solute at the surface irrespective of whether the layer is a mixture or whether there is any aggregation in the bulk solution. Previously, adsorption at air-water interfaces has been determined by applying the Gibbs equation to surface tension (ST) measurements, which requires assumptions about the composition of the surface and about the activity of the solute in the bulk, which, in turn, means that in practice the surface is assumed to consist of the pure solute or of a mixture of pure solutes, and that the activity of the solute in the bulk solution is known. The use of NR in combination with ST-Gibbs measurements makes it possible to (i) avoid these assumptions and hence understand several patterns of ST behaviour previously considered to be anomalous and (ii) to start to analyse quantitatively the behaviour of mixed surfactants both below and above the critical micelle concentration. These two developments in our understanding of the thermodynamics of the air-water interface are described with recent examples.
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Affiliation(s)
- Jeffrey Penfold
- ISIS Facility, Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxon, UK. .,Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, UK
| | - Robert K Thomas
- Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, UK
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2
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Hu X, Gong H, Liu H, Wang X, Wang W, Liao M, Li Z, Ma K, Li P, Rogers S, Schweins R, Liu X, Padia F, Bell G, Lu JR. Contrasting impacts of mixed nonionic surfactant micelles on plant growth in the delivery of fungicide and herbicide. J Colloid Interface Sci 2022; 618:78-87. [PMID: 35334364 DOI: 10.1016/j.jcis.2022.03.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 02/13/2022] [Accepted: 03/01/2022] [Indexed: 10/18/2022]
Abstract
HYPOTHESIS Nonionic alkyl ethoxylate surfactants are widely used in agrochemicals to facilitate the permeation of systemic herbicides and fungicides across the plant waxy film. Industrial grade surfactants are often highly mixed and how the mixing affects their interactions with pesticides and wax films remains largely unexplored. A better understanding could enable design of mixed nonionic surfactants for herbicides and fungicides to maximize their efficiency and reduce wastage whilst controlling their impact on plant wax films. EXPERIMENT In this study, nonionic surfactants with general structure n-oxyethylene glycol monododecyl ether (C12En) were used to form surfactant mixtures with the same average ethoxylate numbers but different hydrophilic-lipophilic balance (HLB) values. Their mixed micellar systems were then used to solubilize a herbicide diuron (DN) and a fungicide cyprodinil (CP), followed by plant wax solubilization upon contact with wax films. These processes were monitored by 1H NMR and SANS. FINDING Pesticide solubilization made surfactant micelles effectively more hydrophobic but subsequent wax dissolution caused pesticide release and the restoration of the micellar amphiphilicity. Nonionic surfactants with lower HLBs form larger nanoaggregates, show enhanced wettability, and have better ability to solubilize and permeate pesticides across the wax film, but may cause significant damage to plant growth. These observations help explain why herbicides applied on weeds would benefit from surfactants with lower HLB values while fungicides require surfactants with HLBs to balance between delivery efficiency and potential phytotoxicity risks.
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Affiliation(s)
- Xuzhi Hu
- Biological Physics Group, Department of Physics and Astronomy, School of Natural Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Haoning Gong
- Biological Physics Group, Department of Physics and Astronomy, School of Natural Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Huayang Liu
- Biological Physics Group, Department of Physics and Astronomy, School of Natural Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Xi Wang
- Department of Materials, School of Natural Sciences, the University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Weimiao Wang
- Department of Materials, School of Natural Sciences, the University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Mingrui Liao
- Biological Physics Group, Department of Physics and Astronomy, School of Natural Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Zongyi Li
- Biological Physics Group, Department of Physics and Astronomy, School of Natural Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Kun Ma
- STFC ISIS Facility, Rutherford Appleton Laboratory, Didcot, OX11 0QX, UK
| | - Peixun Li
- STFC ISIS Facility, Rutherford Appleton Laboratory, Didcot, OX11 0QX, UK
| | - Sarah Rogers
- STFC ISIS Facility, Rutherford Appleton Laboratory, Didcot, OX11 0QX, UK
| | - Ralf Schweins
- Large Scale Structures Group, Institut Laue-Langevin, CS 20 156, 38042 Grenoble CEDEX 9, France
| | - Xuqing Liu
- Department of Materials, School of Natural Sciences, the University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Faheem Padia
- Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire RG42 6EY, UK
| | - Gordon Bell
- Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire RG42 6EY, UK
| | - Jian R Lu
- Biological Physics Group, Department of Physics and Astronomy, School of Natural Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
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Banerjee B, Paria S. Effect of Electrolytes on Solution and Interfacial Behaviors of Double Chain Cationic-Nonionic Surfactant Mixtures for Hydrophobic Surface Wetting and Oil/Water Emulsion Stability Applications. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:10560-10572. [PMID: 34424690 DOI: 10.1021/acs.langmuir.1c01672] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The solution behaviors of the binary mixture of double chain cationic surfactant didodecyldimethylammonium bromide (DDAB) with nonionic surfactants of varied head groups, EO-9 and EO-40, in the presence and absence of electrolytes were studied and found nonideal behavior. The different physicochemical properties such as Gibb's surface excess (Γ), minimum area per molecule (Amin), and interaction parameters at bulk (βM) and interface (βσ) were calculated. In the presence of nonionic surfactants, lowering of CMC, CVC, and surface tension at these two concentrations of DDAB were observed. The βM and βσ values indicate strong interaction between DDAB and EO-40 mixed system. Further, addition of electrolytes to the mixed systems show increased interaction and change of physicochemical properties because of the combination of electrical and salting out effects.
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Affiliation(s)
- Barnali Banerjee
- Interfaces and Nanomaterials Laboratory, Department of Chemical Engineering, National Institute of Technology, Rourkela-769008, Orissa, India
| | - Santanu Paria
- Interfaces and Nanomaterials Laboratory, Department of Chemical Engineering, National Institute of Technology, Rourkela-769008, Orissa, India
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4
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Penfold J, Thomas RK. Recent developments and applications of the thermodynamics of surfactant mixing. Mol Phys 2019. [DOI: 10.1080/00268976.2019.1649489] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Jeffrey Penfold
- ISIS Facility, Rutherford Appleton Laboratory, STFC, Chilton, Didcot, UK
- Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, UK
| | - Robert K. Thomas
- Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, UK
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5
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Smith C, Lu JR, Thomas RK, Tucker IM, Webster JRP, Campana M. Markov Chain Modeling of Surfactant Critical Micelle Concentration and Surface Composition. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:561-569. [PMID: 30540480 DOI: 10.1021/acs.langmuir.8b03624] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
A Markov chain (MC) model has been used to model the following binary surfactant mixtures: linear alkylbenzenesulfonate (LAS4)/octaethylene glycol monododecyl ether (C12E8) at 10 and 25 °C, LAS6/acidic sophorolipid (AS), C12Betaine/C12Maltoside, sodium lauryl ether sulfate (SLES2)/C12E8, and rhamnolipid (R1)/LAS6. The critical micellar concentration and the composition of the adsorbed layer, for each system, can be modeled using the same monomer reactivity ratio values, g1 and g2. This implies that the interactions between the surfactants in the bulk solution and at the interface are the same, within error. For the LAS4/C12E8 system at 25 °C, the ranges of g1 and g2 values which can model both sets of data are within 0.03-0.05 and 1.55-2.10, respectively; g1 ≪ g2 implies that C12E8 is significantly more surface active than LAS4. The MC model indicates a negative change in the free energy upon mixing for all of the surfactant systems, consistent with the literature. The interfacial mixing behavior of LAS4/SLES2 is inferred from the results of the MC analysis of the LAS4/C12E8 and SLES2/C12E8 systems, which share a common surfactant partner in C12E8, and the prediction is in line with the published data.
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Affiliation(s)
- Charles Smith
- Biological Physics Laboratory, School of Physics and Astronomy , University of Manchester , Schuster Building, Oxford Road , Manchester M13 9PL , U.K
| | - Jian Ren Lu
- Biological Physics Laboratory, School of Physics and Astronomy , University of Manchester , Schuster Building, Oxford Road , Manchester M13 9PL , U.K
| | - Robert K Thomas
- Physical and Theoretical Chemistry Laboratory , University of Oxford , South Parks Road , Oxford OX1 3QZ , U.K
| | - Ian M Tucker
- Unilever Research and Development Port Sunlight Laboratory, Quarry Road East , Bebington , Wirral CH63 3JW , U.K
| | - John R P Webster
- STFC , Rutherford Appleton Laboratory , Chilton, Didcot , Oxfordshire OX11 0QX , U.K
| | - Mario Campana
- STFC , Rutherford Appleton Laboratory , Chilton, Didcot , Oxfordshire OX11 0QX , U.K
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6
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Liley J, Penfold J, Thomas R, Tucker I, Petkov J, Stevenson P, Banat I, Marchant R, Rudden M, Webster J. The performance of surfactant mixtures at low temperatures. J Colloid Interface Sci 2019; 534:64-71. [DOI: 10.1016/j.jcis.2018.08.099] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 08/24/2018] [Accepted: 08/27/2018] [Indexed: 11/17/2022]
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7
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Smith C, Lu JR, Tucker IM, Grainger D, Li P, Webster JRP, Thomas RK. Temperature Resistant Binary SLES/Nonionic Surfactant Mixtures at the Air/Water Interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:9442-9452. [PMID: 30010345 DOI: 10.1021/acs.langmuir.8b01093] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Surface compositions of adsorbed monolayers at the air/water interface, formed from binary surfactant mixtures in equilibrium, have been studied using neutron reflectivity at three discrete temperatures: 10, 25, and 40 °C. The binary compositions studied are sodium lauryl dodecyl ether sulfate (SLES EO3)/C12E n, where n = 6 and 8, at a fixed concentration of 2 mM with and without the addition of 0.1 M NaCl. Without NaCl, the nonionic surfactant dominates at the interface and nonideal mixing behavior is observed. This is modeled using the pseudophase approximation with a quadratic expansion of the free energy of mixing. The addition of 0.1 M NaCl screens the charge interaction between the surfactants and drives the surface composition of each system closer to that of the bulk composition. However, model fits to both the micelles and surface layers suggest that nonideal mixing is still taking place, although it is difficult to establish the extent of nonideality due to the limited data quality. The effect of temperature changes on the surface adsorption and composition of the surfactant mixtures is minimal and within error, with and without NaCl, but the critical micelle concentrations are significantly affected. This indicates the dominant influence of steric hindrances and surfactant charge interactions in determining interfacial behavior for these surfactants, relative to the temperature changes. The study also highlights the delicate effect of a relatively small change in the number of EO groups on mixing behavior.
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Affiliation(s)
- Charles Smith
- Biological Physics Laboratory, School of Physics and Astronomy , University of Manchester , Schuster Building, Brunswick Street , Manchester M13 9PL , U.K
| | - Jian R Lu
- Biological Physics Laboratory, School of Physics and Astronomy , University of Manchester , Schuster Building, Brunswick Street , Manchester M13 9PL , U.K
| | - Ian M Tucker
- Unilever Research and Development Port Sunlight Laboratory , Quarry Road East , Bebington , Wirral CH63 3JW , U.K
| | - David Grainger
- Unilever Research and Development Port Sunlight Laboratory , Quarry Road East , Bebington , Wirral CH63 3JW , U.K
| | - Peixun Li
- Rutherford Appleton Laboratory , STFC , Chilton, Didcot , Oxfordshire OX11 0QX , U.K
| | - John R P Webster
- Rutherford Appleton Laboratory , STFC , Chilton, Didcot , Oxfordshire OX11 0QX , U.K
| | - Robert K Thomas
- Physical and Theoretical Chemistry Laboratory , University of Oxford , South Parks Road , Oxford OX1 3QZ , U.K
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Saavedra Moreno Y, Bournival G, Ata S. Analysis of Bubble Coalescence Dynamics and Postrupture Oscillation of Capillary-Held Bubbles in Water. Ind Eng Chem Res 2017. [DOI: 10.1021/acs.iecr.7b03197] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yesenia Saavedra Moreno
- School of Mining Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Ghislain Bournival
- School of Mining Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Seher Ata
- School of Mining Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia
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9
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Peshkova TV, Minkov IL, Tsekov R, Slavchov RI. Adsorption of Ions at Uncharged Insoluble Monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:8858-8871. [PMID: 27529571 DOI: 10.1021/acs.langmuir.6b02349] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A method is proposed for the experimental determination of the adsorption of inorganic electrolytes at a surface covered with insoluble surfactant monolayer. This task is complicated by the fact that the change of the salt concentration alters both chemical potentials of the electrolyte and the surfactant. Our method resolves the question by combining data for the surface pressure versus area of the monolayer at several salt concentrations with data for the equilibrium spreading pressure of crystals of the surfactant (used to fix a standard state). We applied the method to alcohols spread at the surface of concentrated halide solutions. The measured salt adsorption is positive and has nonmonotonic dependence on the area per surfactant molecule. For the liquid expanded film, depending on the concentration, there is one couple of ions adsorbed per each 3-30 surfactant molecules. We analyzed which ion, the positive or the negative, stands closer to the surface, by measuring the effect of NaCl on the Volta potential of the monolayer. The potentiometric data suggest that Na(+) is specifically adsorbed, while Cl(-) remains in the diffuse layer, i.e., the surface is positively charged. The observed reverse Hofmeister series of the adsorptions of NaF, NaCl, and NaBr suggests the same conclusion holds for all these salts. The force that causes the adsorption of Na(+) seems to be the interaction of the ion with the dipole moment of the monolayer.
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Affiliation(s)
- Tatyana V Peshkova
- Department of Physical Chemistry, Faculty of Chemistry and Pharmacy, Sofia University , 1 J. Bourchier Boulevard, 1164 Sofia, Bulgaria
| | - Ivan L Minkov
- Department of Physical Chemistry, Faculty of Chemistry and Pharmacy, Sofia University , 1 J. Bourchier Boulevard, 1164 Sofia, Bulgaria
- Department of Chemistry, Biochemistry, Physiology, and Pathophysiology, Faculty of Medicine, Sofia University , 1 Koziak Street, 1407 Sofia, Bulgaria
| | - Roumen Tsekov
- Department of Physical Chemistry, Faculty of Chemistry and Pharmacy, Sofia University , 1 J. Bourchier Boulevard, 1164 Sofia, Bulgaria
| | - Radomir I Slavchov
- Department of Physical Chemistry, Faculty of Chemistry and Pharmacy, Sofia University , 1 J. Bourchier Boulevard, 1164 Sofia, Bulgaria
- Department of Chemical Engineering and Biotechnology, Cambridge University , Pembroke Street, New Museums Site, CB2 3RA Cambridge, United Kingdom
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10
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Adsorption at the biocompatible α-pinene–water interface and emulsifying properties of two eco-friendly surfactants. Colloids Surf B Biointerfaces 2014; 122:623-629. [DOI: 10.1016/j.colsurfb.2014.07.041] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 07/24/2014] [Accepted: 07/25/2014] [Indexed: 11/19/2022]
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11
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Trujillo-Cayado L, Ramírez P, Pérez-Mosqueda L, Alfaro M, Muñoz J. Surface and foaming properties of polyoxyethylene glycerol ester surfactants. Colloids Surf A Physicochem Eng Asp 2014. [DOI: 10.1016/j.colsurfa.2014.02.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Sandoval TE, Gárate MP, Olea AF. Aggregation of alcohols ethoxylates (CiEOj) in dibutoxymethane and surface activity at the water/dibutoxymethane interface. Colloids Surf A Physicochem Eng Asp 2014. [DOI: 10.1016/j.colsurfa.2013.09.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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14
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Wood MH, Welbourn RL, Charlton T, Zarbakhsh A, Casford MT, Clarke SM. Hexadecylamine adsorption at the iron oxide-oil interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:13735-13742. [PMID: 24106786 PMCID: PMC3850247 DOI: 10.1021/la4018147] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Revised: 10/03/2013] [Indexed: 05/28/2023]
Abstract
The adsorption behavior of a model additive, hexadecylamine, onto an iron surface from hexadecane oil has been characterized using polarized neutron reflectometry, sum-frequency generation spectroscopy, solution depletion isotherm, and X-ray photoelectron spectroscopy (XPS). The amine showed a strong affinity for the metal surface, forming a dense monolayer at relatively low concentrations; a layer thickness of 16 (±3) Å at low concentrations, increasing to 20 (±3) Å at greater amine concentrations, was determined from the neutron data. These thicknesses suggest that the molecules in the layer are tilted. Adsorption was also indicated by sum-frequency generation spectroscopy and XPS, the latter indicating that the most dominant amine-surface interaction was via electron donation from the nitrogen lone pair to the positively charged iron ions. Sum-frequency generation spectroscopy was used to determine the alkyl chain conformation order and orientation on the surface.
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Affiliation(s)
- Mary H. Wood
- Department
of Chemistry and BP Institute, Cambridge
University, Cambridge CB2 1EW, United Kingdom
| | - Rebecca
J. L. Welbourn
- Department
of Chemistry and BP Institute, Cambridge
University, Cambridge CB2 1EW, United Kingdom
| | - Timothy Charlton
- ISIS, Rutherford Appleton Laboratory, Didcot OX11 0QX, United Kingdom
| | - Ali Zarbakhsh
- School
of Biological and Chemical Science, Queen
Mary University of London, Joseph Priestly Building, Mile End Road, London E1 4NS, United Kingdom
| | - M. T. Casford
- Department
of Chemistry and BP Institute, Cambridge
University, Cambridge CB2 1EW, United Kingdom
| | - Stuart M. Clarke
- Department
of Chemistry and BP Institute, Cambridge
University, Cambridge CB2 1EW, United Kingdom
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The role of NaSCN on the equimolar cationic–anionic surfactant mixtures: Evidence from NMR, surface tension and dynamic light scattering. Colloids Surf A Physicochem Eng Asp 2013. [DOI: 10.1016/j.colsurfa.2012.10.029] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Zhang XL, Penfold J, Thomas RK, Tucker IM, Petkov JT, Bent J, Cox A, Campbell RA. Adsorption behavior of hydrophobin and hydrophobin/surfactant mixtures at the air-water interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:11316-11323. [PMID: 21774529 DOI: 10.1021/la201706p] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The adsorption of the surface-active protein hydrophobin, HFBII, and the competitive adsorption of HFBII with the cationic, anionic, and nonionic surfactants hexadecyltrimethylammonium bromide, CTAB, sodium dodecyl sulfate, SDS, and hexaethylene monododecyl ether, C(12)E(6), has been studied using neutron reflectivity, NR. HFBII adsorbs strongly at the air-water interface to form a dense monolayer ∼30 Å thick, with a mean area per molecule of ∼400 Å(2) and a volume fraction of ∼0.7, for concentrations greater than 0.01 g/L, and the adsorption is independent of the solution pH. In competition with the conventional surfactants CTAB, SDS, and C(12)E(6) at pH 7, the HFBII adsorption totally dominates the surface for surfactant concentrations less than the critical micellar concentration, cmc. Above the cmc of the conventional surfactants, HFBII is displaced by the surfactant (CTAB, SDS, or C(12)E(6)). For C(12)E(6) this displacement is only partial, and some HFBII remains at the surface for concentrations greater than the C(12)E(6) cmc. At low pH (pH 3) the patterns of adsorption for HFBII/SDS and HFBII/C(12)E(6) are different. At concentrations just below the surfactant cmc there is now mixed HFBII/surfactant adsorption for both SDS and C(12)E(6). For the HFBII/SDS mixture the structure of the adsorbed layer is more complex in the region immediately below the SDS cmc, resulting from the HFBII/SDS complex formation at the interface.
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Affiliation(s)
- Xiaoli L Zhang
- Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford, United Kingdom
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Campana M, Teichert A, Clarke S, Steitz R, Webster JRP, Zarbakhsh A. Surfactant adsorption at the metal-oil interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:6085-6090. [PMID: 21506534 DOI: 10.1021/la200670w] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The structure of the adsorbed palmitic acid at the iron oxide/oil interface has been investigated using polarized neutron reflectometry. The palmitic acid was found to be strongly adsorbed at the oxide/oil interface resulting in a monolayer of thickness 16 ± 4 Å for 150 and 500 ppm palmitic acid concentrations (16 ± 5 Å for the 1000 ppm solution). These layer thicknesses suggest tilt for the palmitic acid molecules with respect to the interface. The model also requires a second diffuse layer extending in the bulk oil. The thickness of this diffuse layer was 35 ± 17 Å for the 150 ppm solution and 45 ± 22 Å for 500 and 1000 ppm solution. The composition profiles at the interface suggest a depletion of the oil in the vicinity of the interface as the concentration of palmitic acid increases.
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Affiliation(s)
- Mario Campana
- School of Biological & Chemical Sciences, Queen Mary, University of London, Joseph Priestley Building, Mile End Road, London E1 4NS, United Kingdom
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Ramírez P, Pérez LM, Trujillo LA, Ruiz M, Muñoz J, Miller R. Equilibrium and surface rheology of two polyoxyethylene surfactants (CiEOj) differing in the number of oxyethylene groups. Colloids Surf A Physicochem Eng Asp 2011. [DOI: 10.1016/j.colsurfa.2010.11.074] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Bacteria-mediated PAH degradation in soil and sediment. Appl Microbiol Biotechnol 2011; 89:1357-71. [PMID: 21210104 DOI: 10.1007/s00253-010-3072-7] [Citation(s) in RCA: 108] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2010] [Revised: 12/09/2010] [Accepted: 12/09/2010] [Indexed: 10/18/2022]
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the natural environment and easily accumulate in soil and sediment due to their low solubility and high hydrophobicity, rendering them less available for biological degradation. However, microbial degradation is a promising mechanism which is responsible for the ecological recovery of PAH-contaminated soil and sediment for removing these recalcitrant compounds compared with chemical degradation of PAHs. The goal of this review is to provide an outline of the current knowledge of biodegradation of PAHs in related aspects. Over 102 publications related to PAH biodegradation in soil and sediment are compiled, discussed, and analyzed. This review aims to discuss PAH degradation under various redox potential conditions, the factors affecting the biodegradation rates, degrading bacteria, the relevant genes in molecular monitoring methods, and some recent-year bioremediation field studies. The comprehensive understanding of the bioremediation kinetics and molecular means will be helpful for optimizing and monitoring the process, and overcoming its limitations in practical projects.
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Wakeham D, Niga P, Warr GG, Rutland MW, Atkin R. Nonionic surfactant adsorption at the ethylammonium nitrate surface: a neutron reflectivity and vibrational sum frequency spectroscopy study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:8313-8318. [PMID: 20121047 DOI: 10.1021/la9047243] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The adsorbed layers of polyoxyethylene n-alkyl ether surfactants C(12)E(4), C(14)E(4), and C(16)E(4) at the EAN surface have a headgroup layer that is thin and compact (only approximately 30 vol % EAN). The headgroups do not adopt a preferred orientation and are disordered within the ethylene oxide layer. Alkyl tails contain a significant number of gauche defects indicating a high degree of conformational disorder. The thickness of the tail layer increases with increasing alkyl chain length, while the headgroup layer shows little change. Lowering the C(12)E(4) concentration from 1 to 0.1 wt % decreases the adsorbed amount, and the headgroup layer becomes thinner and less solvated, whereas C(14)E(4) and C(16)E(4) adsorbed layers are unaffected by dilution over the same concentration range. The C(16)E(4) layer thickness increases and area per molecule decreases on warming to 60 degrees C, but the adsorbed layer structures of C(12)E(4) and C(14)E(4) are unchanged. Both effects are attributed to surfactant solubility.
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Affiliation(s)
- Deborah Wakeham
- Centre for Organic Electronics, The University of Newcastle, Callaghan, NSW 2308, Australia
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Valenzuela MÁ, Gárate MP, Olea AF. Surface activity of alcohols ethoxylates at the n-heptane/water interface. Colloids Surf A Physicochem Eng Asp 2007. [DOI: 10.1016/j.colsurfa.2007.04.059] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Anton N, Saulnier P, Béduneau A, Benoit JP. Salting-Out Effect Induced by Temperature Cycling on a Water/Nonionic Surfactant/Oil System. J Phys Chem B 2007; 111:3651-7. [PMID: 17388519 DOI: 10.1021/jp0664768] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This paper presents original effects induced by temperature cycling on the transitional phase inversion of emulsions, stabilized by a nonionic polyethoxylated C18E6 surfactant model. The phase inversion follow-up is performed by electrical conductivity measurements, which involves focusing the study on the shape and location of the emulsion inversion region. In that way, new observations are brought out as a gradual evolution of the emulsion inversion along the cycling process. Two alternative approaches are considered for tackling these results: (i) first, a molecular approach regarding the particular organization and rearrangement of water clusters surrounding the surfactant polymer polar head, and (ii) second, a thermodynamic approach only considering the whole Gibbs free energy of the system. The volumic approaches are transposed, here, to the water/oil interface, and disclose that the phase inversion zone is included in a metastable region, able to stabilize for a given temperature, either metastable O/W emulsions or stable W/O ones. In that way, this study proposes novel and complementary insights into the phenomena governing the emulsion phase inversion.
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Affiliation(s)
- Nicolas Anton
- Inserm U646, Ingénierie de la vectorisation particulaire, Université d'Angers, F-49100 Angers, France
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Nonideal mixing of dodecyltrimethylammonium halides and nonionic surfactant in adsorbed films and micelles. Colloid Polym Sci 2003. [DOI: 10.1007/s00396-003-0931-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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