Classifications

• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D17/00—Detergent materials or soaps characterised by their shape or physical properties
  • C11D17/0008—Detergent materials or soaps characterised by their shape or physical properties aqueous liquid non soap compositions
  • C11D17/0017—Multi-phase liquid compositions
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D17/00—Detergent materials or soaps characterised by their shape or physical properties
  • C11D17/0008—Detergent materials or soaps characterised by their shape or physical properties aqueous liquid non soap compositions
  • C11D17/0013—Liquid compositions with insoluble particles in suspension
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D3/00—Other compounding ingredients of detergent compositions covered in group C11D1/00
  • C11D3/39—Organic or inorganic per-compounds
  • C11D3/3947—Liquid compositions
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D3/00—Other compounding ingredients of detergent compositions covered in group C11D1/00
  • C11D3/395—Bleaching agents
  • C11D3/3956—Liquid compositions

Definitions

• This invention relates to cleaning compositions and cleaning methods, employing water-in-oil emulsions.
• bleaches e.g. sodium hypochlorite bleaches
• the bleaches are able to act upon stains and can cause the chemical disruption (oxidation) of the stain and / or its decolouration, and thus masking of the stain.
• Bleaches also provide an anti-microbial action. Bleach performance is dependent upon several factors including the type and concentration of the bleach used. One crucial factor is that of temperature. Many bleach / bleach pre-cursors only reach the required level of activity at or above a certain elevated temperature.
• bleach activators In order to reduce this temperature and thus make the bleaches more convenient to use whilst saving unnecessary energy bleach activators are employed. These bleach activators interact with the bleach / bleach pre-cursor, forming new bleaching species, which are more active at lower temperature.
• bleach activators with bleaches
• cleaning powders and compressed particulate tablets can be produced which contain both bleach and bleach activator in solid form.
• the bleach and bleach activators are segregated with the composition as a further aid to prevent premature reaction .
• a cleaning composition comprising a water-in-oil emulsion, having a plurality of independent aqueous phases, wherein an aqueous phase comprises a bleaching agent.
• the cleaning composition may be rapidly dispersed, e.g. into a wash liquor. This is increasingly important as wash cycles are becoming shorter / using less water for ecological reasons.
• the composition comprises two independent aqueous phases .
• the composition comprises a bleach activator.
• the bleach activator may be present in an aqueous phase or in an oil phase.
• the bleach activator is segregated from the bleaching agent.
• the bleaching agent is segregated from other detersive agents that react detrimentally with bleaching agents, e.g. enzymes, dyes, fragrances.
• the bleach activator is possibly in particulate form.
• the bleach activator is in particulate form generally it has a particle size of 0.0001 to 2mm, e.g. such as 1mm.
• the bleach activator is selected from tetraacetylethylendiamine (TAED) , acetylated triazine derivatives, in particular 1, 5-Diacetyl-2 , 4-dioxohexahydro- 1, 3, 5-triazine ( DADHT ) , acetylated glycoluriles , in particular Tetraacetylglycolurile (TAGU) , acylimides, in particular n-nonanoylsuccinimide (NOSI) , acetylated phenolsulfonates , in particular n-nonanoyloxi or n- lauroyloxibenzolsulfonate (NOBS and/or PRAISE) , acetylated phenol carbonic acids, in particular nonanoyloxi or decanoyloxibenzoesaeure (NOBA and/or DOBA) , carbonic acid anhydrides, acetylated sugar derivatives,
• Bleaching catalysts may be present.
• Preferred examples include complexes of manganese, iron, cobalt, ruthenium, molybdenum, titanium or vanadium.
• manganese salts are in the oxidation state +2 or +3 preferentially, for example manganese halides, whereby the chloride is preferential.
• manganese sulfate, manganese salts of organic acids such as manganese acetates, acetylacetonate, oxalates as well as manganese nitrates are suitable.
• Metal complex with macromolecular ligands may be used such asl, 4, 7-Trimethyl-l, 4, 7-triazacyclononane (me-TACN) , 1,4,7- Triazacyclononane (TACN) , 1, 5, 9-Trimethyl-l , 5, 9- triazacyclododecane (me-TACD) , 2-Methyl-l , , 7 trimethyl- 1, 4, 7-triazacyclononane (MeMeTACN) and/or 2-Methyl-l , 4 , 7 triazacyclononane (Me/TACN) or ligands such as 1,2-bis (4,7- Dimethyl 1 , 4 , 7-triazacyclonono-i-yl ) ethane (Me4-DTNE) .
• Me-TACN 4, 7-Trimethyl-l, 4, 7-triazacyclononane
• TACN 1,4,7- Triazacyclononane
• Me-TACD 2-Met
• the bleaching agent is usually a source of active oxygen, e.g. urea / hydrogen peroxide.
• the bleaching agent may be based on alternative chemistry, e.g. chlorine based bleaching agents, such as hypochlorite bleaches.
• bleaching agents such as phthalimido-peroxy-hexanoic- acid (PAP) per-salts such as; perborate, percarbonate, persulphate; are substantially insoluble in water (e.g. having a solubility of less than 0.6g/litre of demineralised water at 25°C.
• PAP phthalimido-peroxy-hexanoic- acid
• the bleaching agent is suspended in an aqueous phase or in an oil phase.
• a cleaning composition comprising a water-in-oil emulsion, having a plurality of independent aqueous phases, wherein a substantially water insoluble bleaching agent is suspended in an aqueous phase or an oil phase.
• the bleaching agent is in particulate form generally it has a particle size of 0.0001 to 2mm, e.g. such as 1mm.
• the concentration of the hydrogen peroxide is typically from 0.1 to 50%, e.g. 15%.
• the aqueous phases comprises at least 40% by weight of the composition, preferably at least 50% by weight, more preferably at least 60%, more preferably at least 70% and most preferably at least 75% by weight of the composition .
• the oil phase preferably comprises at least 1%, more preferably at least 3%, more preferably at least 5%, and most preferably at least 7% by weight of the composition.
• the oil phase preferably comprises less than 45%, more preferably 35%, and most preferably less than 30% by weight of the composition.
• the oil phase comprises about 25% by weight of the composition.
• the oil phase may be based on widely diverse groups of oils, including natural oils, and mixtures thereof.
• oils suitable for forming the oil phase of the emulsion.
• the oil phase comprises a mineral oil / hydrocarbon such as a paraffin / kerosene.
• compositions of the invention have substantially no transport between the oil and water phases.
• the composition of the present invention preferably further comprises up to 10% by weight of a surfactant, preferably up to 8%, more preferably up to 5%, preferably up to 3%, and most preferably up to 2% by weight of the total composition. It is postulated that the surfactant forms a micelle type barrier around the water particles present in the emulsion.
• the composition comprises at least 0.01% by weight surfactant, preferably at least 0.05%, more preferably at least 0.1% and most preferably at least 0.2% by weight.
• the cleaning composition desirably includes at least one surfactant selected from anionic, cationic, non-ionic or amphoteric ( zwitterionic) surfactants.
• at least one surfactant selected from anionic, cationic, non-ionic or amphoteric ( zwitterionic) surfactants.
• Especially preferred surfactants are those formed by the reaction of succinic acid I or succinic anhydride II, with a polyol, a polyamine or a hydroxylamine .
• R is a hydrocarbon group having from about 12 to about 200 carbon atoms, preferably 12 to about 100 carbon atoms, more preferably 12 to 50 and most preferably 18 to 30 carbon atoms.
• the hydrocarbon group R in the above formulae may be derived from an alpha-olefin or an alpha-olefin fraction.
• the alpha-olefins include 1-dodecene, 1-tridecene, 1- tetradecene, 1-pentadecene , 1-hexadecene, 1-heptadecene , 1- octadecene, 1-eicosene, 1-tricontene, and the like.
• the alpha olefin factions that are useful include Ci 5 -i a alpha- olefins, Ci 2 -i6 alpha-olefins, C 14 -ie alpha-olefins , Ci 4 -ie alpha-olef ins , Ci6-i8 alpha-olefins, C 18 -24 alpha-olefins , C18-30 alpha-olefins , and the like. Mixtures of two or more of any of the foregoing alpha-olefins or alpha-olefin fractions may be used.
• R in the above formulae is a hydrocarbon group derived from an olefin oligomer or polymer.
• the olefin oligomer or polymer may be derived from an olefin monomer of 2 to about 10 carbon atoms, and in one embodiment about 3 to about 6 carbon atoms, and in one embodiment about 4 carbon atoms.
• the monomers include ethylene; propylene; 1-butane; 2-butane; isobutene; 1-pentene; 1- heptene; 1-octane; 1-nonene; 1-decene; 2-pentene; or a mixture of two or more thereof.
• R in the above formulae is a polyisobutene group.
• the polyisobutene group may be made by the polymerization of a C 4 refinery stream having a butene content of about 35 to about 75% by weight and an isobutene content of about 30 to about 60% by weight.
• R in the above formulae is a polyisobutene group derived from a polyisobutene having a high methylvinylidene isomer content, that is, at least about 50% and in one embodiment at least about 70% methylvinylidenes .
• Suitable high methylvinylidenes polyisobutenes include those prepared using boron trifluoride catalysts.
• Suitable polyols include: ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, dibutylene glycol, tributylene glycol, 1-2-butanedoil, 2 , 3-dimethyl- 2, 3-butanediol, 2 , 3-butanediol , 2 , 3-hexanediol , 1,2- cyclohexanediol, pentaerythritol, dipentaerythritol, 1,7- heptanediol, 2 , 4-heptanediol , 1, 2 , 3-hexanetriol, 1,2,5- hexantriol, 2, 3, 4-hexantriol, 1, 2, 3-butanetriol, 1,2,4- butanetriol, 2,2,6, 6-tetrakis- (hydroxymethyl) cyclohexanol, 1, 10-decan
• Suitable polyamines may be aliphatic, cycloaliphatic, heterocyclic or aromatic. Examples include alkylene polyamines and heterocyclic polyamines. Suitable alkylene polyamines include ethylene polyamines, butylene polyamines, propylene polyamines, pentylene polyamines, etc. The higher homologues are related to heterocyclic amines such as piperazines and N-amino alkyl- substituted piperazines are also included.
• polyamines include ethylene diamine, triethylene tetramine, tris- ( 2-aminoethyl ) amine, propylene diamine, trimethylene diamine, tripropylene tetramine, tetraethylene pentamine, hexaethylene heptamine, pentaethylene hexamine or a mixture of two or more thereof.
• the polyamine may also be selected from the heterocyclic polyamines, for example aziridines, azetidines, azolidines, tetra- and dihydropyridines , pyrroles, indoles, piperidines, imidazoles, di- and tetra-hydroimidazoles, piperazines, isoindoles, purines, morpholines, thiomorphines , N- aminoalkylmorpholines , N-aminoalkylthiomorpholines, N- aminoalkylpiperazines , ⁇ , ⁇ ' -diaminoalkylpiperazines , azepines, azocines, azonnes and tetra-, di- and perhydro derivatives of each of the above and mixtures thereof.
• heterocyclic polyamines for example aziridines, azetidines, azolidines, tetra- and dihydropyridines , pyrroles, in
• Useful heterocyclic amines are the saturated 5- and 6- membered heterocyclic amines containing only nitrogen, oxygen and/or sulfur in the hetero ring, especially the piperidines, piperazines, thiomorpholines , morpholines, and pyrrolidines.
• Suitable compounds include piperidine, aminoalkyl-substituted piperidines, piperazine, aminoalkyl- substituted piperazines, morpholine, aminoalkyl-substituted morpholines, pyrrolidine, and N-aminoalkyl-substituted pyrrolidines such as N-aminopropylmopholine, N- aminoethylpiperazine, and N, N' -diaminoethylpiperazine .
• Suitable hydroxyamines may be a primary, secondary or tertiary amine.
• the hydroxyamine may be an N- (hydroxyl ) - substituted alkyl amine, a hydroxyl-substituted polyalkoxy analogue thereof, or a mixture of such compounds .
• the hydroxylamine suitably contains from about 1 to about 40 carbon atoms, preferably 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms.
• Primary, secondary and tertiary hydroxyamines may represented by the following formulae:
• each R is independently an alkyl group of one to about eight carbon atoms or hydroxyl-substituted alkyl group of about two to about 18 carbon atoms. Typically each R is a lower alkyl group of up to seven carbon atoms.
• the group -R' -OH in such formulae represents the hydroxyl-substituted hydrocarbon group.
• R' can be an acrylic, alicyclic or aromatic group.
• R' is an acyclic straight or branched alkylene group such as an ethylene, 1 , 2-propylene, 1, 2-butylene, 1 , 2-octadecylene , etc, group.
• R groups When two R groups are present in the same molecule they can be joined by a direct carbon-to-carbon bond or through a heteroatom (e.g., oxygen, nitrogen or sulfur) to form a 5-, 6-, -7 or 8- members ring structure.
• heterocyclic amines include N- (hydroxyl lower alkyl)- morpholines, thiomorpholines , piperidines, oxazolidines, thiazolidines and the like.
• the hydroxyamines may be either N- (hydroxy-substituted hydrocarbyl ) amines . These may be hydroxyl-substituted poly) alkoxy) analogues of the above-described hydroxy amines (these analogues also include hydroxyl-substituted oxyalkylene analogues). Such N- (hydroxyl-substituted hydrocarbon) amines may be conveniently prepared by reaction of epoxides with afore-described amines.
• alkoxylated alkylene polyamines e.g. N, - (diethanol ) - ethylene diamine
• alkoxylated alkylene polyamines e.g. N, - (diethanol ) - ethylene diamine
• alkoxylated alkylene polyamines include N- (2-hydroxyethyl) ethylene diamine, N,N-bis(2- hydroxyethyl ) -ethylene-diamine, 1- (2-hydroxyethyl) piperazine, mono (hydroxypropyl) -substituted diethylene triamine, di (hydroxypropyl ) -substituted tetraethylene pentamine, N- ( 3-hydroxybutyl ) tetramethylene diamine, etc. Higher homologues are also useful.
• N- (hydroxyl-substituted hydrocarbyl) amines examples include mono-, di-, and triethanolamine, diethylethanolamine, di ( 3-hydroxylpropyl ) amine, N-(3- hydroxybutyl) amine, N- ( 4-hydroxybutyl ) amine, N-,N-di-(2- hydroxypropyl ) amine, N- ( 2-hydroxylethyl ) morpholine and its thio analogue, N- (2-hydroxyethyl ) cyclohexylamine, N-3- hydroxyl cyclopentyl amine, o-, m- and p-aminophenol , N- (hydroxylethyl) piperazine, N, N' -di (hydroxylethyl ) piperazine, and the like.
• hydroxyamines are the hydroxy-substituted primary amines described in US Patent 3,576,743 by the general formula
• R a -NH 2 wherein R a is a monovalent organic group containing at least one alcoholic hydroxy group.
• hydroxy-substituted primary amines include 2-amino-l-butanol, 2-amino-2-methyl-l-propanol , p- (beta-hydroxyethyl) -aniline, 2-amino-l-propanol, 3-amino-l- propanol, 2-amino-2-methyl-l , 3-propanediol, 2-amino-2-ethyl- 1, 3-propanediol , N- (betahydroxypropyl) -N' - (beta-aminoethyl ) - piperazine, tris- (hydroxymethyl ) aminoethane (also known as trismethylolaminomethane) , 2-amino-l-butanol, ethanolamine, beta- (beta-hydroxyethoxy) -ethylamine, glucamine, glucosamine, 4-amino-3-hydroxy-3-methyl-l-
• Hydroxyalkyl alkylene polyamines having one or more hydroxyalkyl substituents on the nitrogen atoms are also useful .
• Examples include N- (2-hydroxyethyl) ethylene diamine, N, N-bis ( 2-hydroxyethyl ) ethylene diamine, 1-
• sorbital trioleate which has an HLB value of 1.8
• octylphenol-l- ethyleneancy which has an HLB value of 4.0
• span 80 sorbital monocleate which has an HLB value of 4.3.
• surfactants not particularly described above may also be used. Those having an HLB value of less than 10 are preferred. Such surfactants are described in McCutcheon' s Detergents and Emulsifiers, North American Edition, 1982; Kirk-Othmer, Encyclopaedia of Chemical Technology, 3rd Ed., Vol. 22, pp 346-387.
• the particles of TAED may be coated / may have been brought into contact with a surfactant to aid the dispersion of the TAED particles in the oil phase.
• Preferred dispersants are certain nonionic surfactants which act by steric hindrance and are active only at the protectant solid/organic liquid interface and do not act as emulsifying agents.
• Such dispersants are suitably made up of:- (a) a polymeric chain having a strong affinity for the liquid, and
• (b) a group which will absorb strongly to the solid.
• dispersants are those of the Hypermer and Atlox lines, available from the ICI group of companies, including Hypermer PS1, Hypermer PS2, Hypermer PS3, Atlox LP1, Atlox LP2 , Atlox LP4, Atlox LP5, Atlox LP6, and Atlox 4912 and Agrimer polymers such as Agrimer AL-216 and AL-220, available from GAF.
• the oil and or water phase of the composition may contain other detergent actives such as enzymes, builders, perfumes, optical brighteners, soil suspending agents, dye transfer inhibition agents.
• a method of preparation of a composition comprising a water-in-oil emulsion, having a plurality of independent aqueous phases, comprising the formation of a plurality of independent water-in-oil emulsions and mixing same together under low shear conditions.
• a cleaning composition comprising a water- in-oil emulsion, having a plurality of independent aqueous phases, wherein an aqueous phase comprises a bleaching agent in a cleaning operation.
• the use is preferably for cleaning hard surfaces e.g. in a dishwashing or kitchen / bathroom / toilet / sanitary ware cleaning operation.
• the use may be associated with a washing machine and be for mechanical laundry and / or dishwashing.
• the use may also be for hand washing e.g. manual laundry.
• Emulsogen OG consists of oleyl hydrophobic chains bonded to polyglcerol and has an average molecular structure of 2 oleyl chains bonded to 2 glycerol units and so is denoted here with the abbreviation 0 2 G 2 .
• the average structure was determined from the manufacturer' s (Clariant) information on the average number of glycerol units per molecule and the measured saponification number to derive the number of oleyl chains.
• Anfomul 2887 an alkanolamine derivative of polyisobutene lactone, is a surfactant which is commonly used to stabilise emulsion explosive HIPEs 16 and was supplied by Croda.
• Additional reagents including urea (Fisher Chemicals, >99%) , acetic acid (Fisher, >99%) , potassium iodide (Sigma, >99%), sodium thiosulphate (Sigma, 99.99%), starch indicator (Sigma), ferroin (Sigma, 0.1 wt% solution), cerium sulphate (Reidel de Haen, >98%), sulphuric acid (Fisher, 98%) and chloroform (Fisher, >99%) were all used as received.
• each high internal phase emulsion was prepared by adding the required volumes of aqueous phase, stabiliser, then oil phase to a 25 x 75 mm (diameter x height) glass tube.
• the samples were emulsified by either vigorous handshaking for 30 seconds or by using a simple overhead paddle stirrer with a single plastic-coated metal stirrer blade of 20 x 30 mm operating at approximately 100 RPM for 1 minute .
• Mean drop diameters were measured by optical microscopy.
• a small volume of the emulsion was extracted from the middle of the emulsion by pipette and diluted into a large volume of the oil used as the continuous phase.
• Diluted samples were held in a 25 x 75 mm cavity microscope slides with a single cavity of 16 mm diameter and 0.2 mm depth which was covered with a cover slip.
• Micrographs of this diluted emulsion were obtained using a Leica DME transmission microscope equipped with a Leica DFC 290 camera. The entire sample field was scanned before acquisition of a micrograph to ensure the final image was representative of the total emulsion drop size distribution which was determined by measuring the diameters of all the drops appearing in a single micrograph (typically 50 to 100 drops) using Leica LAS image analysis software. All parent emulsion drop size distributions were monomodal with polydispersit ies (equal to the standard deviation divided by the mean) of approximately 50%.
• mean drop radii refer to the number average.
• mean drop radii were measured for the "parent" HIPEs containing either the transferring or indicator species and the mixed HIPE containing both species immediately after preparation. The evolution of the drop size in the mixed HIPE over time was also measured.
• Values of the partition coefficient of hydrogen peroxide between water and dodecane under different conditions were determined using one of two methods.
• first, low sensitivity method equal volumes of aqueous hydrogen peroxide and dodecane were equilibrated with gentle stirring for 48 hours. 1 mL of the equilibrated dodecane phase was mixed with 5 mL of 50:50 glacial acetic acid/chloroform and 10 mL of aqueous KI solution (excess) . The iodine liberated was titrated with aqueous sodium thiosulphate solution with starch as indicator 26 . For the initial peroxide concentrations used here, partition coefficients greater than 5 x 10 "4 could be determined by this method.
• a typical experiment to determine the time over which aqueous reagents are maintained in separate water drop compartments of a HIPE was performed as follows.
• a first HIPE (HIPE1) is prepared containing a concentration c A i of an aqueous reagent A, volume fraction of oil ⁇ 0 ⁇ with mean water drops radius rj..
• the concentration c A i is expressed as moles of A per unit volume of water, not the overall emulsion volume.
• a second HIPE containing c B2 of a different aqueous reagent B and volume fraction of oil ⁇ ⁇ 2 with mean water drops radius r 2 .
• FIG. 1 The situation of the mixed HIPE containing similar numbers of A and B water drops held at fixed but random relative locations by the weak gel nature of the HIPE is shown schematically in Figure 1.
• a and B initially located in separate droplets can meet and react together by combination of water drop coalescence and dissolution in and diffusion across the surfactant-coated oil films separating the water drops.
• the oil films separating the droplets may or may not contain excess surfactant in the form of aggregated species including either inverse microemulsion droplets or lyotropic liquid crystalline phases 5 .
• the presence of such surfactant aggregates may solubilise transporting A molecules in the oil and hence cause facilitated transport of A across the oil films.
• a further complication can arise from the fact that, in addition to the mass transport of the species A, it is expected that mass transport of water between the emulsion drops will also occur due to osmotic pressure differences between the two droplet types.
• the experimental systems can be manipulated to suppress contributions arising from water drop coalescence, facilitated mass transport by surfactant aggregates present in the oil films and water mass transport.
• t* is determined solely by a process in which the uncharged species A partitions into, and diffuses across the oil films separating the drops. It is assumed here that the adsorbed surfactant films coating the oil films play no significant role in controlling the rate of permeation of A between droplets.
• the permeation in the mixed HIPE structure is equivalent to a system comprising an aqueous donor compartment initially containing species A at concentration CM separated from an aqueous receiving compartment (containing zero A initially) by a liquid oil membrane of thickness h.
• the area of the oil film A (per unit total volume of the emulsion) is approximately half that of the area of the water drops. Neglecting the distortion of the drops from sphericity gives an approximate expression for A.
• the rate- determining step is the diffusion process across the oil film.
• the processes of entry and exit of transferring molecules into and out of the oil film are both relatively fast.
• this indicator reaction produces a loss of the brownish/pink colour of the permanganate to the white appearance of the HIPE in the absence of added indicator.
• the stoichiometry factor S is 2.5 for this reaction. Measurements of t * were performed by mixing equal volumes of HIPE1 containing 0.75 volume fraction of aqueous phase containing various concentrations of hydrogen peroxide and HIPE2 containing 0.75 volume fraction of aqueous phase containing 0.1 mM KMnC indicator. Both HIPE1 and HIPE2 and the final mixed HIPE contained 0.25 volume fraction of dodecane as oil continuous phase and were stabilised using 1 wt% of Anfomul 2887 surfactant.
• this surfactant concentration was carefully selected to be the minimum required such that no emulsion drop growth was observed over 2 days, i.e. longer than the timescale of the t * measurements.
• this choice of surfactant concentration is expected to minimise possible peroxide mass transport due to drop coalescence and facilitated transport across the oil films by excess surfactant present in the form of reversed micelles or other aggregates present in the oil.
• D dodecane
• K ow partition coefficient for hydrogen peroxide between water and dodecane.
• D was estimated using a literature value of D w for pentane in water at 25°C of 1.06 x 1CT 9 m 2 s "1 27 and assuming that D scales as (molar volume) -0'4 , where the scaling exponent was taken to be intermediate between -1/3 (spherical molecules) and -1/2 (random coil chains) .
• the value of K ow for hydrogen peroxide between pure water and dodecane was measured for a range of aqueous peroxide concentrations using the high sensitivity, back-extraction method described in the experimental section.
• the results, shown in Figure 2 show that K ow is approximately independent of the peroxide concentration (i.e. non-ideality effects are not significant) and is 1.1 x 10 "7 .
• This value of K ow is 3-4 orders of magnitude lower than literature values for hydrogen peroxide partitioning between water can various moderately polar oils such as esters, alcohols and ethers 29"
• K ow has the value corresponding to no excess surfactant present in the oil and that K ow in the presence of 2 M urea but at zero surfactant is reduced by the same factor (5 fold) as measured in the presence of surfactant (Table 1) .
• the mean drop radius r was 33 ⁇ for all the peroxide concentrations which corresponds to an approximate mean oil film thickness (equation 2) of 7.3 um.
• the mean drop radius varies from 9.8 (at low peroxide cone.) to 21 (at high peroxide cone. ) which correspond to oil film thicknesses ranging from 2.2 to 4.7 ⁇ .
• the measured values of t * and their variation with peroxide concentration and urea addition show reasonable agreement with the approximate values calculated using equation 5. Equalising the urea concentrations in both the donor and received droplets (expected to minimise water transport rates due to osmotic pressure differences) does not produce a large change in trapping time.
• FIG. 4 shows the variation of t* with Anfomul 2887 surfactant concentration for HIPEs containing hydrogen peroxide as transporting species, potassium permanaganate as indicator which also contain 2 M urea in the donor droplets.
• t * passes through a maximum which occurs at a surfactant concentration of around 1 wt% for the different peroxide concentrations.
• the mean emulsion drop radii were measured for these systems, both immediately after preparation and after incubation for 27 hours.
• the lower plot of Figure 4 shows the mean drop radius data for the emulsions containing 5 mM hydrogen peroxide.
• the initial mean drop radius decreases progressively with increasing surfactant concentration.
• Significant drop growth by coalescence occurs over 27 hours for emulsions containing less than 1 wt% surfactant whereas no drop growth is observed for higher surfactant concentrations.
• the drop radius plots for the other peroxide concentrations behave similarly.
• the reduction in t* with increasing surfactant concentration (above that corresponding to the maximum in t*) may be due to a mass transport contribution from facilitated transport.
• increased surfactant concentration also leads to a reduction in mean drop radius which, as seen by inspection of equation 5, will also contribute to a reduction in t * in this surfactant concentration range.
• the peroxide trapping times in these HIPEs stabilised by the surfactant 0 2 G 2 are similar to those in HIPEs stabilised by Anfomul 2887 (see Figure 3) .
• the mass transfer rates of the ionic species HCl and NaCIO across the oil films are of a similar order of magnitude to the rates for the uncharged species hydrogen peroxide. If, as is commonly assumed, the partitioning of ionic species between water and oil is negligible, then it is expected that ionic species should remain trapped indefinitely.
• K ow for HCl and NaCIO between water and dodecane are of a similar order of magnitude to that for hydrogen peroxide (10 "7 ).
• the limited partition coefficient data available for ionic solutes distributing between water and apolar oils suggests that this conclusion is indeed valid.
• K ow for HCl partitioning between benzene and water is 8 x 10 " 6 for an aqueous concentration of 0.34 M 31 .
• K ow for CsCl partitioning between toluene and water is 1 x 10-6 20 .
• HIPEs were generally found to be significantly lower than for corresponding systems with dodecane as oil.
• the explanation for this effect could be that K ow is increased for PDMS as but it was observed that the water-in-PDMS emulsion drops were mutually adhesive, i.e. flocculated. Droplet adhesion is expected to produce oils films which are thinner than predicted by equation 2 and hence this effect is likely to contribute to shorter trapping times.
• FIG. 1 Schematic of a mixed water-in-oil HIPE consisting of water droplets containing the transferring species (white) , indicator species (coloured red before reaction and white after reaction) separated by films of the oil continuous phase (green) .
• the inset shows a blow-up of an oil film (mean thickness h) separating white and red droplets. Sufficient mass transfer across the oil films to produce the red-to-white indicator colour change occurs in the measured trapping time t* and produces an overall colour change of the HIPE.
• Figure 2 Variation of partition coefficient of hydrogen peroxide between water and dodecane with aqueous phase peroxide concentration.
• Figure 3 Comparison of measured and calculated values of trapping time t* for the transfer of hydrogen peroxide between water drops in water-in-dodecane HIPEs containing 0.25 volume fraction of dodecane and stabilised by 1 wt% of Anfomul 2887 surfactant.

Landscapes

• Chemical & Material Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Wood Science & Technology (AREA)
• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Detergent Compositions (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=45470592

Family Applications (1)

Country Status (2)

Family Cites Families (7)

• 2011
  • 2011-12-22 EP EP11807721.3A patent/EP2655590A2/de not_active Withdrawn
  • 2011-12-22 WO PCT/GB2011/052553 patent/WO2012085577A2/en active Application Filing

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events