**In Memoriam, Prof. Julio Casado**

*by Mysara E. Mohyaldinn, Anas M. Hassan and Mohammed A. Ayoub* Microemulsions are self-assembled colloidal aggregates formed by a dispersed phase and a continuous phase stabilized by a surfactant. These aggregates may or may not require the presence of a fourth component known as a cosurfactant.

> These systems are of great interest from a chemical point of view because they facilitate the simultaneous presence of a hydrophobic environment and a hydrophilic environment, with which they have an important solubilizing capacity, distributing the solutes between the water, the organic phase, or in surfactant film depending on their physicochemical characteristics. For this reason, they have abundant and interesting applications in different fields such as solubilization or extraction. Likewise, depending on their biocompatibility, they can be used as vehicles for active principles and drugs, improving their adsorption and therefore their efficacy from a pharmacological point of view.

Therefore, and throughout this book, we will see important applications of microemulsions as chemical nanoreactors. In the first place, they can behave as microheterogeneous catalysts, where one can observe both an important catalysis, an effect of increasing the concentration of reagents in one of the domains of the system, and a perfect inhibition, due to the physical separation of the reactants when solubilized in different phases of the system. Thus, in the literature there are a large number of examples where microemulsions have been used as reaction media in chemical, photochemical, and enzymatic processes. Even microemulsions have been used as an alternative system to phase transfer catalysts.

In addition, the diameter of the microdroplets that form the dispersed phase can be modulated, so that the nanoreactor can be scalable. In this sense, microemulsions can be used to control the growth of nanocrystals or the diameter of nanoparticles.

We must not forget the fact that they can be used to modulate mechanisms oriented to stereoselective synthesis.

Last, but not least, it is necessary to underline a final characteristic: their ability to simulate complex biological structures. This makes microemulsions a valuable tool for biomimetic chemistry. Thus, microemulsions have been used as models of biological membranes or as models of water trapped in restricted media.

Leaving aside the chemistry, at the same time that the adventure of editing this book began, on July 2, 2018, Professor Julio Casado died in Salamanca. For this reason, I want to use this prologue to pay tribute. Don Julio Casado-Linarejos was born in Palencia in 1939 and received his PhD in Chemistry from the University of Valladolid in 1965. After the defense of his doctoral thesis, he joined as a postdoctoral researcher with Professor Bak at the University of Copenhagen, establishing on his return the first microwave laboratory in Spain.

**II**

**Section 3**

and Well Stimulation

Technological Applications **111**

**Chapter 7 113**

Application of Emulsions and Microemulsions in Enhanced Oil Recovery

In 1973, at only 34 years of age, he was appointed Professor at the University of Santiago de Compostela (Galicia), where he formed a research group on chemical kinetics that has trained a large part of chemistry teachers in the university district of Galicia, constituting a school to which I have the honor of belonging as one of his disciples. Within this research group, the chemistry of nitroso compounds was studied in a very detailed way, both in aqueous and non-aqueous media. From these studies, and under the direction of Professor Leis and Professor Elena Peña, we addressed the study of the chemistry of these compounds in microheterogeneous media. In Santiago de Compostela he was also Vice-Rector of the University and Director of the Institute of Educational Sciences. Later, he moved to the University of Salamanca where he finished his research career, first as a professor and then as emeritus, and not without leaving an important imprint among the Galician physical chemists.

In his curriculum, it should be noted that he received the Medal of the Real Spanish Society of Chemistry and the Prize of Investigation Aldrich Chemistry. He was named Doctor Honoris Causa by the University of Vigo, where I had the honor of being his godfather. In addition, I occupy the direction of the Spanish National Agency of Evaluation and Prospective.

 This old Castilian by birth, but Galician by adoption, was, above all, a citizen of the world, who not only taught us chemistry but also to be better people. He was a man who always related with sympathy to people regardless of their social status or political ideology, and who always knew how to see goodness in the human being; he left a deep impression on all those who had the good fortune to know him.

**V**

His deep culture turned him into a true Renaissance man who devoted his life to

**Juan C. Mejuto**

Spain

University of Vigo,

Physical Chemistry Department,

teaching science with rigor and, above all, with love.

*Sit tibi terra levis*

His deep culture turned him into a true Renaissance man who devoted his life to teaching science with rigor and, above all, with love.

*Sit tibi terra levis*

**Juan C. Mejuto** Physical Chemistry Department, University of Vigo, Spain

**IV**

physical chemists.

Agency of Evaluation and Prospective.

In 1973, at only 34 years of age, he was appointed Professor at the University of Santiago de Compostela (Galicia), where he formed a research group on chemical kinetics that has trained a large part of chemistry teachers in the university district of Galicia, constituting a school to which I have the honor of belonging as one of his disciples. Within this research group, the chemistry of nitroso compounds was studied in a very detailed way, both in aqueous and non-aqueous media. From these studies, and under the direction of Professor Leis and Professor Elena Peña, we addressed the study of the chemistry of these compounds in microheterogeneous media. In Santiago de Compostela he was also Vice-Rector of the University and Director of the Institute of Educational Sciences. Later, he moved to the University of Salamanca where he finished his research career, first as a professor and then as emeritus, and not without leaving an important imprint among the Galician

In his curriculum, it should be noted that he received the Medal of the Real Spanish Society of Chemistry and the Prize of Investigation Aldrich Chemistry. He was named Doctor Honoris Causa by the University of Vigo, where I had the honor of being his godfather. In addition, I occupy the direction of the Spanish National

This old Castilian by birth, but Galician by adoption, was, above all, a citizen of the world, who not only taught us chemistry but also to be better people. He was a man who always related with sympathy to people regardless of their social status or political ideology, and who always knew how to see goodness in the human being; he left a deep impression on all those who had the good fortune to know him.

Section 1

Chemical Kinetics and

Microheterogeneous Catalysis

1

Section 1
