Methods of evaluating a surfactant may include ultrasonicating a mixture of oil, water, and the surfactant to form at least one of the following: a sub-macroemulsion, a macroemulsion phase or a combination of the aforementioned; separating the sub-macroemulsion from the macroemulsion phase; introducing the sub-macroemulsion into a foam container; performing a first automated phase identification of the sub-macroemulsion; introducing a gas into the sub-macroemulsion to generate a column of foam, where the column of foam has a height in the foam container; performing a second automated phase identification of the sub-macroemulsion; and measuring the height of the column of foam in the foam container. In these methods, the first and second automated phase identifications may be configured to quantify one or more liquid phases and a foam phase in the column.

A method for determining interfacial tension of a hydrocarbon in a brine fluid, the method including injecting a first brine fluid into a test cell, the first brine fluid having an initial ionic composition, injecting a hydrocarbon fluid into the test cell, contacting the hydrocarbon fluid with the first brine fluid, forming a droplet, measuring the interfacial tension of the hydrocarbon fluid in contact with the first brine fluid, at least partially displacing the first brine fluid with an inert gas, measuring a ionic composition salinity of the displaced first brine fluid in an ionic chromatograph, and comparing the measured ionic composition salinity to the initial ionic composition.

A method is provided for determining the surface viscosity of a liquid in which a thread is formed from a drop of the liquid. The thread is lengthened and its minimum radius h.sub.0 is determined at multiple times between the thread formation and thread pinch-off. The minimum radius and associated time values are used to determine a linear relationship of minimum radius and time, with the coefficient of the linear relationship, or the slope X of the line in the linear relationship, corresponding to the surface viscosity μ.sub.s of the liquid according to one of the following equations:

[00001]$\begin{array}{cc}x=\frac{0.0709}{1+5B_{\mathrm{s0}/3h_0}},& \left(1\right)\end{array}$

where B.sub.s0=μ.sub.s/μR in which h.sub.0 is defined as above, R is the dimension of the feature on which the drop is provided and μ is the bulk viscosity of the liquid, or

[00002]$\begin{array}{cc}x=\frac{0.0304}{\mathrm{Oh}\left(1+5b_{\mathrm{s0}/3h_0}\right)},& \left(2\right)\end{array}$

in which Oh=μ/√{square root over (ρRσ)}, where μ and R are as defined above, ρ is the density of the liquid, and σ is the surface tension of the liquid without surfactants.

A method for determining interfacial tension of a hydrocarbon in a brine fluid, the method including injecting a first brine fluid into a test cell, the first brine fluid having an initial ionic composition, injecting a hydrocarbon fluid into the test cell, contacting the hydrocarbon fluid with the first brine fluid, forming a droplet, measuring the interfacial tension of the hydrocarbon fluid in contact with the first brine fluid, at least partially displacing the first brine fluid with an inert gas, measuring a ionic composition salinity of the displaced first brine fluid in an ionic chromatograph, and comparing the measured ionic composition salinity to the initial ionic composition.

The present invention provides devices, systems and methods for installing water potential detectors in plants stems, measuring the water potential in the plants, and evaluating crop irrigation conditions.

A method includes determining a critical micelle concentration (C.sub.cm assumed) of a sample with an unknown concentration (C.sub.s) of a surfactant based on an assumed surfactant concentration (C.sub.assumed) of the sample, providing a benchmark solution with a known concentration of the surfactant, determining an actual critical micelle concentration (C.sub.cm) of the surfactant from the benchmark solution, and calculating the unknown concentration (C.sub.s) of the surfactant in the sample from the following equation: C.sub.s=C.sub.cm/(C.sub.cm assumed/C.sub.assumed).

A method includes determining a critical micelle concentration (C.sub.cm assumed) of a sample with an unknown concentration (C.sub.s) of a surfactant based on an assumed surfactant concentration (C.sub.assumed) of the sample, providing a benchmark solution with a known concentration of the surfactant, determining an actual critical micelle concentration (C.sub.cm) of the surfactant from the benchmark solution, and calculating the unknown concentration (C.sub.s) of the surfactant in the sample from the following equation: C.sub.s=C.sub.cm/(C.sub.cm assumed/C.sub.assumed).

A method for determining interfacial tension of a hydrocarbon in a brine fluid, the method including injecting a first brine fluid into a test cell, the first brine fluid having an initial ionic composition, injecting a hydrocarbon fluid into the test cell, contacting the hydrocarbon fluid with the first brine fluid, forming a droplet, measuring the interfacial tension of the hydrocarbon fluid in contact with the first brine fluid, at least partially displacing the first brine fluid with an inert gas, measuring a ionic composition salinity of the displaced first brine fluid in an ionic chromatograph, and comparing the measured ionic composition salinity to the initial ionic composition.

Methods of evaluating a surfactant may include ultrasonicating a mixture of oil, water, and the surfactant to form at least one of the following: a sub-macroemulsion, a macroemulsion phase or a combination of the aforementioned; separating the sub-macroemulsion from the macroemulsion phase; introducing the sub-macroemulsion into a foam container; performing a first automated phase identification of the sub-macroemulsion; introducing a gas into the sub-macroemulsion to generate a column of foam, where the column of foam has a height in the foam container; performing a second automated phase identification of the sub-macroemulsion; and measuring the height of the column of foam in the foam container. In these methods, the first and second automated phase identifications may be configured to quantify one or more liquid phases and a foam phase in the column.

A method for measuring the critical micelle concentration of a surfactant solution is provided. The method includes preparing surfactant solutions with different concentration of the surfactant, measuring transmittance profiles of the surfactant solutions in a dispersion analyser under centrifugal force, translating changes in the transmittance profiles of the surfactant solutions to a sedimentation velocity, and using a relationship between the sedimentation velocity and the surfactant concentration to determine the critical micelle concentration of the surfactant.