US-12624218-B1 - Carbon black-based aqueous suspensions with improved stability

US12624218B1US 12624218 B1US12624218 B1US 12624218B1US-12624218-B1

Abstract

A method for enhancing the dispersion stability of carbon black-based aqueous suspensions is provided. The method includes forming a thin sodium dodecyl sulfate (SDS) monolayer on the outer surface of the carbon black materials before the carbon black materials are dispersed in a base fluid. This is done by mixing SDS with dry carbon black powder at a ratio of about 1:0.5 by weight for about 15 minutes, under a controlled environment. After mixing the SDS with dry carbon black powder, the resulting mixture is added to distilled water and dispersed for 45 minutes using a sonicator. Once the dispersion process is completed, the suspension is stored for future use.

Inventors

Naser Alsayegh
Nawaf F. Aljuwayhel
Husain Ashkanani
Yousef Abdullah Altourah

Assignees

KUWAIT UNIVERSITY

Dates

Publication Date: 20260512
Application Date: 20250915

Claims (5)

1 . A method of making a carbon-black based suspension, the method comprising: mixing sodium dodecyl sulfate with dry carbon black powder at a ratio of about 1:0.5 by weight for about 15 minutes, under a controlled environment, to obtain a mixture; and adding the mixture to distilled water and dispersing the mixture within the water using a sonicator to obtain the carbon-black based suspension; wherein the temperature of the controlled environment is between about 20° C. and about 27° C. and the humidity of the controlled environment is between about 30% and about 50%; and wherein the sonicator is a probe sonicator.
2 . The method of claim 1 , wherein mixing sodium dodecyl sulfate with dry carbon black powder comprises hand mixing.
3 . The method of claim 2 , wherein the hand mixing comprises mixing with a mortar and pestle.
4 . A method of making a carbon-black based suspension, the method consisting of: hand mixing sodium dodecyl sulfate with dry carbon black powder at a ratio of about 1:0.5 by weight for about 15 minutes, under a controlled environment, to obtain a mixture; and adding the mixture to distilled water and dispersing the mixture within the water using a sonicator to obtain the carbon-black based suspension; wherein the temperature of the controlled environment is between about 20° C. and about 27° C. and the humidity of the controlled environment is between about 30% and about 50%; and wherein the sonicator is a probe sonicator.
5 . The method of claim 4 , wherein the hand mixing is mixing with a mortar and pestle.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application is a divisional of U.S. patent application Ser. No. 19/206,421, filed on May 13, 2025, the entire contents of which are incorporated herein by reference. FIELD AND BACKGROUND OF THE INVENTION The present disclosure relates to carbon black-based aqueous suspensions, and particularly to methods of improving the stability of carbon black-based aqueous suspensions. DESCRIPTION OF THE PRIOR ART Suspensions are advanced heat transfer fluids engineered by dispersing millimeter-to nanometer-sized particles in conventional base fluids like water, ethylene glycol, or oils. Suspensions containing dispersed micrometer-sized particles in a base fluid are commonly known as ‘Microfluids’. Suspensions containing dispersed nanometer-sized particles in a base fluid are commonly known as ‘Nanofluids’. These innovative liquids have significantly enhanced thermal properties when compared to their conventional counterparts, making them highly effective in various heat transfer applications, such as solar collectors, liquid cooled computers, air conditioning (AC) systems, and the like. Traditionally, there are two main approaches to producing these suspensions. The first technique is known as the one-step (or single-step) method and the second technique is called the two-step method. In the single-step approach, particles are formed and dispersed within a base fluid in a single stage. The advantages of this approach include the production of a suspension having a higher dispersion physical stability; and avoiding the need to transport, store, and utilize a dry powder. The drawbacks of this method include difficulties in removing residual reactants resulting from incomplete reactions, and limitations regarding the specific particles and base fluids that are compatible with a single-step approach. The traditional two-step method uses pre-prepared powders (microparticles or nanoparticles), which are added and dispersed in a non-dissolving base fluid using a mixing device such as an ultrasonicator, a homogenizer, and magnetic stirring. The advantages of this approach are that any type of suspension can be manufactured, the method is relatively easy and can be performed by users with a minimum level of experience, the powders are commercially available on a wide scale, and the method can be adapted for both small- and large-scale production. However, suspensions made using the two-step method generally have lower dispersion physical stability when compared to suspensions made by the one-step method. Thus, methods of improving the stability of carbon black-based aqueous suspensions solving the aforementioned problems are desired. SUMMARY OF THE INVENTION A method for enhancing the dispersion stability of carbon black-based aqueous suspensions is provided. The method includes forming a thin sodium dodecyl sulfate (SDS) monolayer on the outer surface of the carbon black materials before the carbon black materials are dispersed in a base fluid. This is done by mixing SDS with dry carbon black powder at a ratio of about 1:0.5 by weight for about 15 minutes, under a controlled environment. After mixing the SDS with dry carbon black powder, the resulting mixture is added to distilled water and dispersed for 45 minutes using a sonicator. Once the dispersion process is completed, the suspension is stored for future use. In an embodiment, mixing the SDS with dry carbon black powder may comprise hand mixing. In a further embodiment, the hand mixing may comprise using a mortar and pestle. In an embodiment, the temperature of the controlled environment can be set to about 20° C. to about 27° C. and the humidity of the controlled environment can be set to about 30% to about 50%. These and other features of the present subject matter will become readily apparent upon further review of the following specification. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagram depicting the process used to form a SDS monolayer on carbon black particles. FIG. 2 is a graph illustrating an XRD analysis of carbon black (CB), functionalized CB, and CB mixed with SDS. FIG. 3 depicts an FTIR analysis of CB, functionalized CB, and CB mixed with SDS. FIG. 4 depicts a graph of a XPS analysis of CB and functionalized CB. FIGS. 5A-5F depict FE-SEM images showing the morphology of the CB (FIGS. 5A-5B), functionalized CB (FIGS. 5C-5D), and CB mixed with SDS (FIGS. 5E-5F). FIG. 6 depicts a stability analysis of suspension made of the CB, functionalized CB, CB mixed with SDS, and CB mixed with SDS and dispersed in water on Day 1 and on Day 7. FIG. 7 depicts a graph showing particle size analyzer results for suspensions made of CB, functionalized CB, CB mixed with SDS, and CB mixed with SDS and dispersed in water. FIG. 8 depicts a summary of the changes in dispersion stability behavior observed for the suspensions made of CB, functionalized CB, CB mixed with SDS, and CB mixed with SDS and dispersed in water. Similar reference