Process for the preparation of water-in-oil and oil-in-water nanoemulsions

Abstract

Process for the preparation of a water-in-oil or oil-in-water nanoemulsion wherein the dispersed phase is distributed in the dispersing phase in the form of droplets having a diameter ranging from 1 to 500 nm, comprising: 1) the preparation of a homogeneous water/oil blend (I) characterized by an interface tension lower than 1 mN/m, comprising water in an amount of 30 to 70% by weight, at least two surface-active agents having a different HLB, selected from non-ionic, anionic, polymeric surface-active agents, said surface-active agents being present in such a quantity as to make the blend homogeneous; 2) the dilution of the blend (I) in a dispersing phase consisting of oil or water with the addition of a surface-active agent, selected from non-ionic, anionic, polymeric surface-active agents, the quantity of the dispersing phase and surface-active agent being such as to obtain a nanoemulsion having a HLB different from that of the blend (I).

Claims

1. A low energy process for the preparation of an oil-in-water nanoemulsion wherein a dispersed phase is distributed in a dispersing phase in the form of droplets having a diameter ranging from 1 to 500 nm, said process consisting of: diluting a homogeneous water/oil blend (I) having an interface tension lower than 1 mN/m and comprising water in an amount of 30 to 70% by weight and at least two surface-active agents having a different HLB, said surface-active agents being selected from the group consisting of non-ionic surface-active agents, anionic surface-active agents, and polymeric surface-active agents, and said surface-active agents being present in said water/oil blend (I) an amount of from 5 to 50% by weight in a dispersing phase consisting of water and a surface-active agent selected from the group consisting of a non-ionic surface-active agent, an anionic surface-active agent, and a polymeric surface-active agent, the quantity of the dispersing phase and the surface-active agent being sufficient to obtain an oil-in-water nanoemulsion having an HLB higher than that of said homogeneous water/oil blend (I), wherein during dilution a spontaneous and instantaneous phase inversion occurs, together with the formation of the nanoemulsion.

2. The process according to claim 1, wherein, in the homogeneous blend (I), the weight ratio between the surface-active agents produces a HLB value higher than 8.

3. The process according to claim 2, wherein the surface-active agents are selected from non-ionic surface-active agents and the weight ratio between the surface-active agents produces a HLB ranging from 10 to 15.

4. The process according to claim 2, wherein the surface-active agents are selected from anionic surface-active agents and the weight ratio between the surface-active agents produces a HLB higher than 20.

5. The process according to claim 2, wherein the weight proportion between the concentration of surface-active agents in the blend and the quantity of water/oil to be dispersed varies from 0.07 to 3.5.

6. The process according to claim 5, wherein the weight proportion between the concentration of surface-active agents in the blend and the quantity of water/oil to be dispersed varies from 0.1 to 2.

7. The process according to claim 1, wherein the surface-active agents having a different HLB are selected from non-ionic and polymeric surface-active agents.

8. The process according to claim 1, wherein the surface-active agents having a different HLB are selected from the group consisting of a first surface-active agent selected from non-ionic lipophilic surface-active agents (type A), a second surface-active agent selected from non-ionic hydrophilic surface-active agents (type B), and a third surface-active agent selected from polymeric surface-active agents (type C), the composition of surface-active agents (A)+(B)+(C) having a HLB ranging from 8 to 16.

9. The process according to claim 8, wherein the composition of surface-active agents (A)+(B)+(C) has a HLB ranging from 10 to 15.

10. The process according to claim 1, wherein the surface-active agents having a different HLB consist of a non-ionic lipophilic surface-active agent of the group of esters of fatty acids with a HLB lower than 11, a non-ionic hydrophilic surface-active agent of the group of alkyl glucosides with a HLB higher than 11 and a non-ionic polymeric surface-active agent with a HLB varying from 4 to 14.

11. The process according to claim 1, wherein the oil-in-water nanoemulsion is prepared by dissolving a hydrophilic surface-active agent in water and slowly adding the homogeneous blend (I) under stirring, said hydrophilic surface-active agent being selected from the group consisting of non-ionic surface-active agents and polymeric surface-active agents.

12. The process according to claim 1, wherein the diluting of the blend (I) is performed at a temperature ranging from 5 C. to 60 C.

13. The process according to claim 1, wherein the quantity of dispersing phase and the surface-active agent is sufficient to obtain a nanoemulsion having an HLB 0.5 units higher with respect to that of homogeneous water/oil blend (I).

14. The process according to claim 13, wherein: homogeneous water/oil blend (I) comprises non-ionic and polymeric surface-active agents, the dispersing phase consists of water and a non-ionic surface-active agent selected from the group consisting of alkyl glucosides, and the quantity of dispersing phase and surface-active agent is sufficient to obtain a nanoemulsion having a HLB at least 0.8-5 units higher than homogeneous water/oil blend (I).

15. The process according to claim 1, wherein the oil for the preparation of the oil-in-water nanoemulsion is selected from the group consisting of linear hydrocarbons, branched hydrocarbons, and complex hydrocarbon blends.

16. The process according to claim 15. wherein the oil is selected from the group consisting of dodecane, diesel, kerosene, soltrol, and mineral spirits.

17. The process according to claim 1, wherein the water for the preparation of the oil-in-water nanoemulsion is selected from the group consisting of demineralised water, saltwater, and water containing additives.

Description

EXAMPLES

(1) In the following examples, the procedures are described for preparing water-in-oil nanoemulsions with increasing quantities of dispersed water.

Example 1

(2) Formulation of the precursor.

(3) The precursor suitable for the formulation of water-in-oil nanoemulsions, in which the oil is dodecane and the dispersed phase is deionised water, can be formulated according to the following procedure.

(4) 0.177 g of Atlox 4914 (Uniqema), 1.563 gr of Span 80 (Fluka) and 3.588 gr. of Glucopone 600 CS UP (Fluka, 50% water solution) are weighed in a single container and dissolved in 8.233 gr. of dodecane. When the dissolution is complete, 6.439 gr. of deionised water are added under vigorous stirring by means of a magnetic stirrer. The precursor is characterized by a HLB value of 10.8 and is indefinitely stable.

Example 2

(5) Formulation of nanoemulsions with 6.8% of water as dispersed phase.

(6) 0.073 gr of Span 80 are dissolved in 8.275 gr of dodecane in order to obtain 10 gr of nanoemulsion. 1.652 gr of precursor, as prepared in example 1, are slowly added under stirring (magnetic stirrer) to this solution. The emulsion obtained has a transparent-translucent appearance, it is characterized by a HLB value of 9.6 and has the following composition: total surface-active agents=3.65% by weight dodecane=89.55% by weight water=6.8% by weight

(7) The nanoemulsion thus formulated has droplets of dispersed phase around 30-40 nm, a polydispersity index lower than 0.1 and it is stable for over a year.

Example 3

(8) Formulation of nanoemulsions with 10% of water as dispersed phase.

(9) 0.096 gr of Span 80 are dissolved in 7.475 gr of dodecane in order to obtain 10 gr of nanoemulsion. 2.429 gr of precursor, as prepared in example 1, are slowly added under stirring (magnetic stirrer) to this solution. The emulsion obtained has a transparent-translucent appearance, it is characterized by a HLB value of 9.7 and has the following composition: total surface-active agents=5.25% by weight dodecane=84.75% by weight water=10% by weight

(10) The nanoemulsion thus formulated has droplets of dispersed phase around 30-50 nm, a polydispersity index lower than 0.15 and is stable for over a year.

Example 4

(11) Formulation of nanoemulsions with 20% of water as dispersed phase.

(12) 0.131 gr of Span 80 are dissolved in 5.010 gr of dodecane in order to obtain 10 gr of nanoemulsion. 4.858 gr of precursor, as prepared in example 1, are slowly added under stirring (magnetic stirrer) to this solution. The emulsion obtained has a transparent-translucent appearance, it is characterized by a HLB value of 10 and has the following composition: total surface-active agents=9.9% by weight dodecane=70.1% by weight water=20% by weight

(13) The nanoemulsion thus formulated has droplets of dispersed phase around 40-60 nm, a polydispersity index lower than 0.2 and it is stable for over six months.

(14) In the following series of examples the procedures are described for preparing water-in-oil nanoemulsions containing additive solutions as dispersed phase, with different concentrations of additives and dispersed phase.

Example 5

(15) Preparation of a precursor containing a 5% by weight solution of a hydrosoluble additive.

(16) The precursor suitable for the formulation of water-in-oil nanoemulsions, in which the oil is dodecane and the dispersed phase is an aqueous solution containing 5% by weight of a scale inhibitor, can be formulated according to the following procedure.

(17) 0.151 gr of Atlox 4914 (Unigema), 1.191 gr of Span 80 (Fluka) and 3.342 gr of Glucopone 600 CS UP (Fluka, 50% solution in water) are weighed in a single container and are dissolved in 8.153 gr of dodecane. When the dissolution is complete, 6.823 gr of a 5% by weight aqueous solution of an scale inhibitor (for example a phosphino-polycarboxylic acid or a sodium phosphono-carboxylate) are added under vigorous stirring on a magnetic stirrer. The blend thus obtained is characterized by a HLB value of 11.35 and is indefinitely stable.

Example 6

(18) Preparation of a precursor containing a 10% weight solution of a hydrosoluble additive.

(19) The precursor suitable for the formulation of water-in-oil nanoemulsions, in which the oil is dodecane and the dispersed phase is an aqueous solution containing 10% by weight of an scale inhibitor, can be formulated according to the following procedure.

(20) 0.151 gr of Atlox 4914 (Unigema), 1.023 gr of Span 80 (Fluka) and 3.676 gr of Glucopone 600 CS UP (Fluka, 50% solution in water) are weighed in a single container and are dissolved in 7.828 gr of dodecane. When the dissolution is complete, 6.656 gr of a 10% weight aqueous solution of an scale inhibitor (for example a phosphino-polycarboxylic acid or a sodium phosphono-carboxylate) are added under vigorous stirring on a magnetic stirrer. The blend thus obtained is characterized by a HLB value of 12 and is indefinitely stable.

Example 7

(21) Preparation of a precursor containing a 15% weight solution of a hydrosoluble additive.

(22) The precursor suitable for the formulation of water-in-oil nanoemulsions, in which the oil is dodecane and the dispersed phase is an aqueous solution containing 15% by weight of a scale inhibitor, can be formulated according to the following procedure.

(23) 0.151 gr of Atlox 4914 (Unigema), 0.869 gr of Span 80 (Fluka) and 3.985 gr of Glucopone 600 CS UP (Fluka, 50% solution in water) are weighed in a single container and are dissolved in 7.519 gr of dodecane. When the dissolution is complete, 6.501 gr of a 15% by weight aqueous solution of a scale inhibitor (for example a phosphino-polycarboxylic acid or a sodium phosphono-carboxylate) are added under vigorous stirring on a magnetic stirrer. The blend thus obtained is characterized by a HLB value of 12.60 and is indefinitely stable.

Example 8

(24) Formulation of nanoemulsions with the addition in aqueous phase of scale inhibitors.

(25) 0.081 gr. of Span 80 are dissolved in 3.094 gr of dodecane, in order to obtain 10 gr of nanoemulsion. 2.826 gr of precursor, as prepared in example 5, are added to this solution, slowly and under stirring (magnetic stirrer). The emulsion obtained has a transparent-translucent appearance, it is characterized by a HLB value of 10.30 and has the following composition: total surface-active agents=8.57% by weight dodecane=71.09% by weight water=19.53% by weight additive=0.83% by weight

(26) The nanoemulsion thus formulated has droplets of dispersed phase around 40-60 nm, a polydispersity index lower than 0.2 and it is stable for over six months.

Example 9

(27) Formulation of nanoemulsions with the addition in aqueous phase of scale inhibitors.

(28) 0.074 gr. of Span 80 are dissolved in 8.3 gr of dodecane, in order to obtain 10 gr of nanoemulsion. 1.6 gr of precursor, as prepared in example 6, are added to this solution, slowly and under stirring (magnetic stirrer). The emulsion obtained has a transparent-translucent appearance, it is characterized by a HLB value of 10.35 and has the following composition: total surface-active agents=3.25% by weight dodecane=89.71 by weight water=6.5% by weight additive=0.55% by weight

(29) The nanoemulsion thus formulated has droplets of dispersed phase around 40-60 nm, a polydispersity index lower than 0.2 and it is stable for over six months.

Example 10

(30) Formulation of nanoemulsions with the addition in aqueous phase of scale inhibitors.

(31) 0.101 gr. of Span 80 are dissolved in 7.5 gr of dodecane, in order to obtain 10 gr of nanoemulsion. 2.4 gr of precursor, as prepared in example 6, are added to this solution, slowly and under stirring (magnetic stirrer). The emulsion obtained has a transparent-translucent appearance, it is characterized by a HLB value of 10.45 and has the following composition: total surface-active agents=4.75% by weight dodecane=84.71% by weight water=9.72% by weight additive=0.83% by weight

(32) The nanoemulsion thus formulated has droplets of dispersed phase around 40-60 nm, a polydispersity index lower than 0.2 and it is stable for over six months.

Example 11

(33) Formulation of nanoemulsions with the addition in aqueous phase of scale inhibitors.

(34) 0.134 gr. of Span 80 are dissolved in 6.3 gr of dodecane, in order to obtain 10 gr of nanoemulsion. 3.5 gr of precursor, as prepared in example 6, are added to this solution, slowly and under stirring (magnetic stirrer). The emulsion obtained has a transparent-translucent appearance, it is characterized by a HLB value of 10.6 and has the following composition: total surface-active agents=6.84% by weight dodecane=77.68% by weight water=14.27% by weight additive=1.21% by weight

(35) The nanoemulsion thus formulated has droplets of dispersed phase around 40-60 nm, a polydispersity index lower than 0.2 and it is stable for over six months.

Example 12

(36) Formulation of nanoemulsions with the addition in aqueous phase of scale inhibitors.

(37) 0.157 gr. of Span 80 are dissolved in 5.134 gr of dodecane, in order to obtain 10 gr of nanoemulsion. 4.709 gr of precursor, as prepared in example 6, are added to this solution, slowly and under stirring (magnetic stirrer). The emulsion obtained has a transparent-translucent appearance, it is characterized by a HLB value of 10.7 and has the following composition: total surface-active agents=8.91% by weight dodecane=70.41% by weight water=19.07% by weight additive=1.62% by weight

(38) The nanoemulsion thus formulated has droplets of dispersed phase around 40-60 nm, a polydispersity index lower than 0.2 and it is stable for over six months.

Example 13

(39) Formulation of nanoemulsions with the addition in aqueous phase of scale inhibitors.

(40) 0.070 gr. of Span 80 are dissolved in 3.105 gr of dodecane, in order to obtain 10 gr of nanoemulsion. 2.826 gr of precursor, as prepared in example 7, are added to this solution, slowly and under stirring (magnetic stirrer). The emulsion obtained has a transparent-translucent appearance, is characterized by a HLB value of 11.54 and has the following composition: total surface-active agents=8.62% by weight dodecane=70.35% by weight water=18.61% by weight additive=2.41% by weight

(41) The nanoemulsion thus formulated has droplets of dispersed phase around 40-60 nm, a polydispersity index lower than 0.2 and it is stable for over six months.

(42) In the following series of examples the procedures are described for preparing water-in-oil nanoemulsions with different types of oil as continuous phase.

Example 14

(43) Formulation of nanoemulsions with the addition in aqueous phase of scale inhibitors, using gas oil, or soltrol or mineral spirits as continuous phase.

(44) Nanoemulsions can be obtained by indifferently using one of the above-mentioned hydrocarbons by applying the following procedure.

(45) 0.085 gr. of Span 80 are dissolved in 3.090 gr of diesel or soltrol or mineral spirits to obtain 6 gr of nanoemulsion. 2.826 gr of precursor, prepared with the same procedure described in example 6, but using gas oil or soltrol or mineral spirits as organic phase, are added to this solution, slowly and under stirring (magnetic stirrer). The emulsion obtained has a transparent-translucent appearance, it is characterized by a HLB value of 10.8 and has the following composition: total surface-active agents=8.7% by weight hydrocarbon=70.6% by weight water=19.1% by weight scale inhibitor=1.6% by weight

(46) The nanoemulsion thus formulated has droplets of dispersed phase around 40-60 nm, a polydispersity index lower than 0.2 and it is stable for over six months.

Example 15

(47) Formulation of nanoemulsions with the addition in aqueous phase of scale inhibitors, using kerosene as continuous phase.

(48) 0.068 gr. of Span 80 are dissolved in 3.106 gr of kerosene to obtain 6 gr of nanoemulsion. 2.826 gr of precursor, prepared with the same procedure described in example 6, but using kerosene as organic phase, are added to this solution, slowly and under stirring (magnetic stirrer). The emulsion obtained has a transparent-translucent appearance, it is characterized by a HLB value of 11.0 and has the following composition: total surface-active agents=8.5% by weight hydrocarbon=70.8% by weight water=19.1% by weight scale inhibitor=1.6% by weight

(49) The nanoemulsion thus formulated has droplets of dispersed phase around 40-60 nm, a polydispersity index lower than 0.2 and it is stable for over six months.

(50) In the following series of examples the procedures are described for preparing water-in-oil nanoemulsions with the addition of additives in both the continuous and dispersed phase.

Example 16

(51) Preparation of the precursor with the addition in aqueous phase of scale inhibitors and in the organic phase of wax/asphaltene inhibitors.

(52) The precursor suitable for the formulation of water-in-oil nanoemulsions, in which oil is a 10% solution by weight of a wax/asphaltene inhibitor (FX 1972 of Ondeo Nalco) in dodecane and the dispersed phase is an aqueous solution containing 10% by weight of a scale inhibitor, can be formulated according to the following procedure.

(53) 0.151 gr of Atlox 4914 (Uniqema), 0.946 gr of Span 80 (Fluka) and 3.831 gr of Glucopone 600 CS UP (Fluka 50% water solution) are weighed in a single container and are dissolved in 7.836 gr. of a solution of wax/asphaltene inhibitor in dodecane. When the dissolution is complete, 6.579 gr. of a 10% by weight water solution of a scale inhibitor (for example polycarboxylic phosphine acid or a sodium phosphono-carboxylate) are added under vigorous stirring on a magnetic stirrer. The blend thus obtained, characterized by a HLB value of 12.30 is indefinitely stable.

Example 17

(54) Formulation of nanoemulsions with the addition in aqueous phase of scale inhibitors and in the organic phase with wax/asphaltene inhibitors.

(55) 0.097 gr of Span 80 are dissolved in 2.549 gr of a 10% by weight solution of wax/asphaltene inhibitor in dodecane in order to obtain 5 gr of nanoemulsion. 2.355 gr of a precursor, as prepared in example 16, are slowly added under stirring (magnetic stirrer) to this solution. The emulsion obtained has a transparent-translucid appearance, it is characterized by a HLB value of 10.75 and has the following composition: total surface-active agents=9.4% by weight dodecane=62.6% by weight water=19.5% by weight additive in aqueous phase (scale inhibitor)=1.6% by weight additive in organic phase (wax inhibitor)=6.9% by weight.

(56) The nanoemulsion thus formulated has droplets of dispersed phase around 30-40 nm, a polydispersity index lower than 0.2 and it is stable for over six months.

Example 18

(57) Formulation of nanoemulsions with the addition in aqueous phase of scale inhibitors and in the organic phase with corrosion inhibitors.

(58) 0.157 gr of Span 80 are dissolved in 5.134 gr of a solution containing 1300 ppm of a corrosion inhibitor (Inicor R200 of Lamberti) in dodecane in order to obtain 10 gr of nanoemulsion. 4.709 gr of a precursor prepared by using additive-free dodecane as organic phase and, as aqueous phase, a 10% solution of a scale inhibitor, as described in example 6, are slowly added under stirring (magnetic stirrer) to this solution. The emulsion obtained has a transparent-translucid appearance, it is characterized by a HLB value of 10.70 and has the following composition: total surface-active agents=8.9% by weight dodecane=70.4% by weight water=19.1% by weight additive in aqueous phase (scale inhibitor)=1.6% by weight additive in organic phase (corrosion inhibitor)=700 ppm.

(59) The nanoemulsion thus formulated has droplets of dispersed phase around 3040 nm, a polydispersity index lower than 0.2 and it is stable for over six months.

(60) In the following series of examples the procedures are described for preparing oil-in-water emulsions.

Example 19

(61) Formulation of the precursor for oil-in-water nanoemulsions.

(62) The precursor suitable for the formulation of oil-in-water nanoemulsions, in which the oil is dodecane and the dispersed phase is deionised water, can be formulated according to the following procedure.

(63) 0.177 g of Atlox 4913 (Uniqema), 1.284 gr of Span 80 (Fluka) and 4.147 gr. of Glucopone 600 CS UP (Fluka, 50% water solution) are weighed in a single container and are dissolved in 8.233 gr. of dodecane. When the dissolution is complete, 6.160 gr. of deionised water are added under vigorous stirring by means of a magnetic stirrer. The precursor is characterized by a HLB value of 12 and is indefinitely stable.

Example 20

(64) Formulation of oil-in-water nanoemulsions with 6.8% of dodecane as dispersed phase.

(65) 0.174 gr of Span 80 are dissolved in 4.8 gr of water. 1.0 gr of a precursor as prepared in example 19, are slowly added under stirring (magnetic stirrer) to this solution. The emulsion obtained has a transparent-translucent appearance, it is characterized by a HLB value of 13.5 and has the following composition: total surface-active agents=4.4% by weight dodecane=6.8% by weight water=88.8% by weight

(66) The nanoemulsion thus formulated has droplets of dispersed phase around 30-40 nm, a polydispersity index lower than 0.2 and it is stable for over six months.

(67) Some comparative examples are provided hereunder which demonstrate that nanoemulsions are not obtained if the procedures claimed in this patent are not followed.

Example 21 (Comparative)

(68) Mixing of the ingredients of the nanoemulsion corresponding to example 4 (20% aqueous phase) without following the procedure indicated in the patent.

(69) 0.043 gr of Atlox 4914 (Uniqema), 0.51 gr of Span 80 (Fluka) and 0.88 gr of Glucopone 600 CS UP (Fluka, 50% water solution) are dissolved in 7 gr of dodecane and 1.57 gr of water are added. A suspension is obtained having the same composition as the nanoemulsion of example 4 and the same HLB=10, but the appearance is opaque and milky and the dispersed phase has droplets having dimensions of over 1 micron.

(70) Composition of the suspension: total surface-active agents=9.9% dodecane=70.1% water=20%

Example 22 (Comparative)

(71) Preparation of a nanoemulsion having a non-optimal final HLB.

(72) The precursor blend having a HLB of 10.8 is prepared as in example 1. The water-in-oil nanoemulsion containing 20% of dispersed phase is formulated however so as to be characterised by a HLB of 9.6 instead of HLB=10, as indicated in example 4. 0.214 gr of Span 80 (Fluka) are dissolved in 4.928 gr of dodecane. 4,858 gr of a precursor blend prepared as in example 1 are slowly added under stirring to the solution thus obtained. A suspension is obtained characterised by a HLB of 9.6 but having an opaque and milky appearance, with the dimensions of the dispersed phase droplets higher than 500 nm.

(73) Suspension composition: total surface-active agents=10.7% dodecane=69.3% water=20%

Example 23 (Comparative)

(74) Preparation of a nanoemulsion by the dilution of a non-homogeneous precursor blend

(75) 0.177 gr of Atlox 4914 (Uniqema), 1.744 gr of Span 80 (Fluka) and 3.226 gr. of Glucopone 600 CS UP (Fluka, 50% water solution) are weighed in a single container and are dissolved in 8.233 gr. of dodecane in order to prepare the precursor blend. When the dissolution is complete, 6.620 gr. of deionised water are added under vigorous stirring by means of a magnetic stirrer. The precursor is characterized by a HLB value of 10.2 and is separated into two phases. 0.033 of Span 80 (Fluka) are dissolved in 5.100 gr of dodecane. 4.900 gr of a precursor mix prepared as described in this example, are slowly added, under stirring to the solution thus obtained.

(76) A suspension is obtained, characterised by a HLB of 10, but having an opaque and milky appearance, with the tendency of depositing into two phases.

(77) Suspension composition: total surface-active agents=9% dodecane=71% water=20%.

Example 24

(78) Example of the preparation of a micro-emulsion with the aim of defining the HLB suitable for the formulation of the nanoemulsion.

(79) In order to obtain a homogeneous micro-emulsion with a HLB of 9.6, containing 7% of aqueous phase, a concentration of surface-active agent of at least 7% is necessary. In particular, 0.763 gr of Span 80 (Fluka), 1.134 gr of Glucopone CS UP (Fluka 50% water solution) and 0.070 gr of Atlox 4914 (Uniqema) are dissolved in 17.2 gr of dodecane and 0.81 gr of water are added, under stirring until a homogeneous product is obtained. A limpid micro-emulsion is thus obtained having a HLB of 9.6 with a composition equal to: total surface-active agents=7% water=7% dodecane=86%
Nanoemulsion applications upstream:

Example 25

(80) Behaviour to temperature:

(81) Nanoemulsions prepared according to the procedure described in example 6, with a weight composition equal to 70.4% of dodecane, 19.1% of water, 8.9% of surface-active agents and 1.6% of scale inhibitor of the group of phosphono-succinic succinic acids, are charged into an autoclave at a pressure of 30 bars and maintained at temperatures of 60 C., 80 C., 100 C. for 8 hours.

(82) The nanoemulsion remains unaltered up to a temperature of 80 C., when it begins to show a slight separation of the aqueous phase. At a temperature of 100 C., the aqueous phase is completely separated, allowing the release of the hydrosoluble additive, which follows the same destiny as the aqueous phase.

Example 26

(83) Behaviour to flushing on a porous medium:

(84) A column having a height of 20 cm and a diameter of 1.9 cm is packed with quartzite having a particle-size greater than 230 mesh and flushed with dodecane at a temperature of 90 C. The initial permeability to dodecane proves to be 55 mD, with a pore volume (PV) equal to 28.9 cm.sup.3.

(85) 180 ml (equal to 6.2 PV) of a nanoemulsion prepared according to the procedure described in example 6, with a composition by weight equal to 70.4% of dodecane, 19.1% of water, 8.9% of surface-active agents and 1.6% of a scale inhibitor of the group of phosphono-succinic acids is flushed in the quartzite column at a flow-rate of 120 mg/h and a temperature of 90 C., maintaining an overpressure of 2.8 bars. Under these conditions, the nanoemulsion separates the aqueous phase containing the scale inhibitor, allowing it to be released and deposited on the quartzite.

(86) At the end, the column is flushed again with dodecane until the complete separation of the nanoemulsion, and the permeability to dodecane is determined again.

(87) During the flushing of the nanoemulsion, the pressure differential (p) undergoes a slight increase, passing from 1.9 to 3.1, due to the greater viscosity of the emulsion with respect to the dodecane, the final permeability to dodecane, however, is not modified with respect to its initial value, confirming that the nanoemulsion is filterable and non-damaging.

(88) At the end of the test, the quartzite contained in the column is discharged and analyzed to evaluate the adsorption of the inhibitor, which proves to be equal to 0.6 mg/g quartzite (4% with respect to the total), typical of scale inhibitors of this group (REF: M. Andrei, A. Malandrino, Petrol. Sci Technol., 2003, 21 (7-8)1295-1315).