Please notice that my e-mail address has changed. Preferred one is at CHE.UAH.EDU
Office: EB 131 ++++ Phone : (256) 824-7313 ++++ FAX: (256) 824-6839
To find out about my research group, please go to the Faculty Research and point and click on my name.
B.S., Universidad Nacional del Litoral, Santa Fe, Argentina (1965)
M.S., University of California at Davis (1968)
Ph.d., University of California at Davis (1970)
Correspondent Fellow, National Research Council of Argentina
Correspondent Member, National Academy of Engineering of Argentina
Fellow of the American Institute of Chemical Engineers
SACNAS is a national scientific society that seeks to encourage underrepresented minority students at all levels to develop interest in science, mathematics and engineering and, ultimately, to pursue graduate education in the sciences. The E-mentoring Program is a yearlong partnership between a teacher and a scientist that involves email approximately once a week. The teams work together depending on their mutual interests; however, typical interactions involve questions about each others' work, successful strategies for teaching content and specific questions regarding how to engage students in understanding a topic with which the scientist is well-versed. Finally, to help focus the interactions, the partners develop a final project together (often a curriculum unit or set of lessons) that will be shared at an annual conference
Contact Line Dynamics and Langmuir-Blodgett Thin Film Deposition.
Thin organic films have become one of the fastest growing applied areas of chemical engineering. Applications of ordered thin films are, among others, nonlinear optic devices, bio-sensors, and bio-resistant/bio-compatible protective coatings. One of the oldest methods for manufacturing thin organized monolayers is the Langmuir-Blodgett technique.
Despite of its many advantages, the Langmuir-Blodgett technique has not made a large impact in the organized thin-film area because of the apparent inability to control the process and hydrodynamic variables needed for reliable thin film deposition. Most of the problems associated with the Langmuir-Blodgett technique can be traced back to the complex dynamics of the gas-liquid-solid moving contact line. Recent experimental and theoretical advances on the dynamics of moving contact lines can be used to understand the fundamentals of L-B film deposition
This research focus on two aspects that will improve understanding of the mechanics of LB depositions and enhance the applicability of this technique to industrial scale operation:
This research is done in collaboration with the group of Leeds University (UK) directed by Professor Michael Savage. The strength of this research is the team approach that is being used to analyze the experimental and theoretical aspects of this problem. This research will answer important practical questions and will provide a physical model for reliable operation of the LB technique. The physical model will improve understanding of experimental data and pave the way for developing faster industrial-scale methods to manufacture ordered thin films. This research will impact the fabrication of biologically compatible materials, and extremely sensitive chemical-detecting or bio-detecting devices.
Flow Patterns Associated to the Steady Movement of a Solid/Liquid/Fluid Contact Line, by M. Savelski, W. B. Kolb, S. Shetty, and R. L. Cerro. J. Colloid & Interfase Sci., 176, 117-127, 1995.
Moving Contact Lines and Langmuir-Blodgett Deposition, by R. L. Cerro. Presented at the AIChE Annual Meeting, Dallas, 1999.
AMIDIQ, Mexican Academy for Education and Research in Chemical Engineering, Ixtapa, Mexico, May 1-5, 2001: Intermolecular forces and flow near a three-phase contact line, by J. Fuentes, M. Savage and R. L. Cerro.Abstract of Paper AMIDIQ 2001
AIChE Annual Meeting, Reno, NV, November 4-9, 2001. Effect of intermolecular forces on flow patterns near a moving contact line. Session 182: General Papers in Fluid Mechanics. J. Fuentes and R. L. Cerro.
Moving Contact Lines and LangmuirBlodgett Film Deposition by R. L. Cerro. J. Colloid and Interface Science, vol 257, 276-283, (2003). Reprint of article JCIS 2003
Moving Contact Lines and Langmuir-Blodgett Film Depositions: Windows of Coatability, by M. E. Diaz Martin, J. Fuentes and R. L. Cerro Presented at 11th ISCST Symposium, Minneapolis, MN September 2002.Extended Abstract, Minneapolis 2002
Transition from Split Streamlines to Dip-Coating During Langmuir-Blodgett Film Deposition, by M. E. Diaz Martin and R. L. Cerro. Thin Solid Films, vol. 460, pp 274-278, 2004
Flow Patterns and Interfacial Velocities Near a Moving Contact Line, by J. Fuentes and R. L. Cerro. Experiments in Fluids, vol 38, pp 503-510, 2005
The Effects of Deposition Velocity and pH on the Order and Structure of Cadmium Arachidate Langmuir-Blodgett Films, by E. Diaz Martin, B. Johnson, K. Chittur and R. L. Cerro. Langmuir, vol. 21, pp 61-616, 2005
On the Effect of Molecular Forces on Moving Contact Lines, by J. Fuentes, M. Savage and R. L. Cerro. To be submitted Journal of Fluid Mechanics, (2004). Preprint of article Journal of Fluid Mechanics 2004
ON THE EFFECT OF SUBPHASE pH AND COUNTERIONS ON TRANSFER RATIOS AND DYNAMIC CONTACT ANGLES DURING DEPOSITION OF MULTIPLE LANGMUIR-BLODGETT MONOLAYERS , by E. Diaz Martin and R. L. Cerro. Thin Solid Films, vol. 485, pp. 224-229, 2005p> Flow Bifurcation during Removal of a Solid from a Liquid Pool. AIChE Annual Meeting, San Francisco, CA. 2003, by E. Diaz Martin and R. L. Cerro. To be submitted Journal of Colloid and Interface Science, (2004). Preprint of article Journal of Colloid and Interface Science 2004
Surface Potentials and Ionization Equilibrium in Y-type Deposition of Multiple Langmuir-Blodgett Films: I. Effect of pH and Counterions, by E. Diaz Martin and R. L. Cerro. JCIS, vol. 285, pp 686-693, 2005
Surface Potentials and Ionization Equilibrium in Y-type Deposition of Multiple Langmuir-Blodgett Films: II. Theoretical Model, by E. Diaz Martin, F. J. Montes and R. L. Cerro. To be submitted Journal of Colloid and Interface Science , (2004). JCIS, vol 285, pp 694-702 2005
Development of a Continuous Langmuir-Blodgett Trough.
Extending the frontiers of computer and communication technology depends on fabricating complex structures with increasingly small feature size with rapid conversion between optical and electronic forms of information. Organic materials continue to play a significant role in fabricating both optical and electronic devices, but the demand for higher device density and interconnections mandates continued research on thin film organic and polymeric materials. Such films are used directly for transferring high resolution patterns to create integrated circuits (microchips), as protective coatings, and as pathways for optical circuits. In biotechnology, thin organic films play an important role as bio-compatible coatings and biosensors.
The objective of this research is to develop a practical method for the deposition of ultra-thin, ordered layers and to explore the immediate application of these coatings on the fabrication of VLSI chips, the production of biosensors and bio-compatible coatings, and as optically active materials. Central to this research is the demonstration of a continuous Langmuir-Blodgett (LB) trough based on hydrodynamic compression of an insoluble monolayer, allowing the fabrication of ordered, multi-layered, stress-free coatings that will be tested for a variety of properties and applications. Subsequently we also plan to investigate novel nonlinear optical geometries using LB films to maximize second harmonic generation. This research program will generate valuable data in the fabrication of ultra-thin films and has a strong probability for technology transfer and continued industrial support.
The deposition of multiple organic monolayers is important to the lithographic process used in the fabrication of VLSI chips, the development of biosensors and in a variety of optical applications including non-linear optical devices. The LB technique is considered by many investigators as the best technique for making such ordered films on solid substrates. There are few practical applications of multi-layered, ordered organic films due to the difficulty of preparing such ordered films quickly and reliably. Current LB troughs are inherently limited by the need for intermittent compression and alignment of the monolayer at liquid-air interfaces by moving mechanical barriers followed by the transfer of the monolayer to solid substrates. Continuous compression devices have been proposed but none has been developed for industrial applications.
A continuous trough will be developed where the compression of a floating insoluble monolayer will be achieved by hydrodynamic shear at the liquid surface. Preliminary results indicate the feasibility of hydrodynamic compression and continuous transfer to a rotating, partially submerged drum. To insure the practical industrial applications of this development, the continuous trough must include the ability to control, in-situ, the properties of the insoluble monolayers obtained by hydrodynamic compression. This project represents an important extension of a comprehensive effort undertaken by The University of Alabama in Huntsville to develop applications in optoelectronics technology. This research will deliver a totally new approach to building ultra thin coatings, combining the proven outstanding properties usually found in LB films with the ability to manufacture films at an economically feasible pace. Completion of this research will open a large number of technological applications for LB films.
Application of Affinity Chromatography and Immobilized Metal Affinity Chromatography to Novel Techniques such as Web-Chromatography and Simulated moving Bed Chromatography .
The technique of affinity chromatography is one of the chromatographic methods chosen because it has the greatest resolving power and the ability for large scale production of any of the protein separation methods. Among the affinity techniques, this research explores Immobilized Metal Affinity Chromatography (IMAC), which has a mechanism based on the reversible interaction between specific amino acid chains and immobilized metal ions. IMAC, a technique growing in popularity, shares some of the characteristics of high affinity, high specific immune-affinity chromatography and the wider spectrum of less specific adsorption techniques, such as ion-exchange chromatography. IMAC is superior to other chromatographic methods in terms of ligand stability, production capacity, and cost, without loss of biological activity due to non-specific adsorption to the affinity matrix. IMAC can be operated under mild conditions to avoid denaturation and there is little immunogenic contamination when compared to immuno-affinity chromatography.
This research is focused on two novel solid-fluid contacting methods and on a specific separation problem. The contacting methods are (i) simulated moving bed chromatography (SMB), and (ii) a continuous counter-current method based on thin films denoted web chromatography. These separation methods will be applied to standard test separations and, as a major development task, to the purification of the enzyme, superoxide dismutase (SOD), from blood plasma. To take advantage of counter-current continuous operations one must develop a clear understanding of the role of adsorption equilibrium, adsorption rates, and mass transfer rates in the overall adsorption process. This research will lay the groundwork for separation techniques to be applied in modular form for the large scale separation of proteins needed for use in pharmaceuticals and fine biochemicals
This research also includes an academic collaboration with the Department of Chemical and Textile Engineering of the Universidad de Salamanca in Spain. Collaborative efforts are already under way on many experimental and theoretical aspects of this research. The group at UAH has unique expertise on interfacial flows, colloid and interfacial chemistry, Langmuir-Blodgett depositions, chromatography, and IR analysis. Professors Cerro and Chittur, the PI and Co-PI of this proposal, are currently studying the effect of moving contact lines on Langmuir-Blodgett depositions. Professor Chittur, the Co-PI of this proposal is a recognized expert in FTIR techniques used to characterize ordered thin films on solid surfaces. Professor Chittur is also the Director of the multidisciplinary PhD program in Biotechnology. Professor Hayes, the second Co-PI of this proposal is a recognized expert in protein recovery using water-in-oil microemulsions, and with biocatalysis in nonaqueous media. The group at Salamanca has invaluable experience with affinity chromatography. Professor Miguel Galan is recognized worldwide for his contributions in biotechnology and catalysis and has been working for many years on affinity chromatography separations. Professor Francisco J. Montes' research focuses on the use of enzymes for the racemic resolution of amino acids. A doctoral graduate from Salamanca, Dr. Eva Martin del Valle is currently at UAH in charge of implementing substrate activations, activation tests, and standard tests for measurement of protein concentration and activity. The two teams are already working closely together and sharing techniques and experimental insights. The grant we are seeking from NSF will consolidate these industrial and academic partnerships in a synergistic manner to accelerate achievement of results.
On the use of ceramic monoliths as stationary phase in affinity chromatography by E. Martin del Valle, M. A. Galan Serrano and R. L. Cerro. Biotechnology Progress, vol 19, 921-927, (2003). Reprint of article Biotechnology Progress 2003
Modeling of monolith-supported affinity chromatography by F. J. Montes, E. Martin del Valle, M. A. Galan Serrano and R. L. Cerro. Biotechnology Progress, Article in Print, (2004). Reprint of article Biotechnology Progress 2004
Applied Research in the Manufacture of Catalytic Converters
This is a project sponsored by the Alabama Research Institute and Engelhard, Corp. The main areas of research are the following: 1) Characterization of Alumina-Base Metal Oxide Suspensions; 2) Fundamental Analysis of New Coating Processes; 3) Fundamentals of Flow Inside Square Capillaries.
The second area, Analysis of New Coating Processes, uses a recently developed unifying theory to understand the fundamentals of coating processes. The emphasis of this research is on new coating processes. The latest work was done during 1995-96 and was the foundation to develop technology for the coating of metallic monoliths. Coating metals with alumina slurries is a totally different process than coating ceramic monoliths. We have now some very interesting insights and an expertise that would allow us to coat metals of any shape and use them as catalysts support.
Coating of Metallic Monoliths
This project is part of a continued research effort between the University of Alabama in Huntsville and Engelhard Corporation. The first phase of this project started in October 1998 sponsored with grant 1ARI99 07 granted by the Alabama Research Institute.
The second phase of this project, is focused on the optimization of coating processes for the manufacture of catalytic converters using metallic monoliths. The use of metallic monoliths has increased substantially during the past five years. The use of metallic supports has practical advantages and is more appropriate for meeting new, more stringent pollution-control requirements. Metallic monoliths have a much shorter start-up time, smaller backup pressure, and better shock resistance than their ceramic counterparts. Auto manufacturers seem to favor metallic monoliths because they are easier to mount on car frames.
Coating of metallic monoliths is done with slurries that have physical properties almost identical to the slurries used on coating of ceramic monoliths. Most slurries were designed for catalytic performance rather that coatability and little has been done to change the nature of slurries, to compensate for the change in substrate
Important variables in coating metallic monoliths are slurry rheology, metal surface preparation, interfacial tension, and dynamic contact angles. These properties can be conditioned by chemical and thermal pre-treatment of the metal surfaces.
The Measurement of Square Channel Velocity Profiles Using a Microcomputer-based Image Analysis System, by C. Camp, B. Kolb, K. Sublette, and R. L. Cerro. Experiments in Fluids 10 , 87-92, (1990).
Coating the Inside of a Capillary of Square Cross Section, by W. Blake Kolb and R. L. Cerro. Chem. Engng. Science 46 , 2181, (1991).
The Motion of Long Bubbles in Tubes of Square Cross Section, by W. Blake Kolb and R. L. Cerro. Physics of Fluids A:Fluid Dynamics , 5 , 1549, (1993).
Film Flow in the Space Between a Circular Bubble and a Square Tube, by W. Blake Kolb and R. L. Cerro. J. Colloid and Interf. Science , 159 , 302, (1993).
The Coating of Monolithic Structures for the Manufacture of Catalytic Converters, by W. B. Kolb, A. Papadimitrious, D. Leavitt, J. Summers, and R. L. Cerro. Chem. Engng. Progress , February 1993.
Liquid Filament Rise in Corners of Square Capillaries: A Novel Method for the Measurement of Small Contact Angles, by A. Lopez de Ramos and R. L. Cerro. Chem. Engng. Science , 49 , 2395, (1994).
Surface Tension from Pendant Drop Curvature, by A. Lopez de Ramos, R. Redner, and R. L. Cerro. Langmuir , 9 , 3691, (1994).
The effect of interfacial properties on performance of packing materials is not well understood. Wetting and interfacial effects have not been fully addressed in the design literature. Understanding the mechanics of wetting and liquid spreading and the role of interfacial properties on the distribution of liquid in packed beds will have important consequences in the design of gas-liquid contactors.
Experiments are conducted on flat surfaces with varying degrees of inclination in order to obtain a detailed description of the hydrodynamic parameters controlling liquid spreading on perfectly wetting systems. This analysis is being extended to surfaces with macro-structures similar to the corrugations found in ordered packings and to the spreading and steady flow of perfectly wetting fluids and partially wetting fluids over surfaces with micro-structure. The micro-structure of the surfaces used in these experiments is similar to the micro-structures found in ordered packing materials.
Flow patterns are visualized using high-spped video recording. The centerpiece of this experimental setup is a high-speed imaging system Kodak Ektapro EM 1200. This is a state-of-the-art high-speed video system with a capability of up to 1,000 frames/second, full frame, and up to 12,000 frames/second, split frame. A triggered stroboscopic flash can be used as a light source with light bursts lasting a millionth of a second such as to essentially freeze images in every frame. All images are stored in RAM with no moving parts, and the images are easily stored in tape using a convential VCR or in a personal computer through digital interface.
The experimental setup for flow visualizations has three major components: 1) flow control and measurement devices; 2)optical tables with mechanical and optical accessories for building flow experiments; and 3)two independent, computer-based, image analysis systems and a two-component Laser-Doppler Velocimeter. There are two computer-based image analysis systems. One of the image analysis systems is based on a 80286-16 MHz computer, and the other is on an 80486-33 MHz computer. Both systems have a TARGA-16 board, a large, high-resolution TV monitor, and versatile VCR recorders. There are three charge-coupled device (CCD) cameras; an all-purpose camera, a monochrome high-resolution camera, and a high-speed color camera.
Experimental Characterization of Viscous Flows over Complez Surfaces, by L. Zhao and R. L. Cerro. Int. J. of Multiphase Flows , 18 , 495, (1992).
Flow Patterns Associated with the Steady Movement of a Solid/Liquid/Fluid Contact Line, by M. J. Savelski, S. A. Shetty, W. B. Kolb, and R. L. Cerro. J. Colloid Interface Sci. , 176 , 117, (1995)
Spreading of Liquid Point Sources over Inclined Solid Surfaces, by S. Shetty and Ramon L. Cerro. I&EC Research , 34 , 4078, (1995).
Fundamental Correlations for the Computation of Design Parameters for Ordered Packings, by S. Shetty and Ramon L. Cerro. I&EC Research , 36 , 771, (1997).
Spreading of a Liquid Point Source over Ordered Packings, by S. Shetty and Ramon L. Cerro. I&EC Research, 36 ,626 (1997).
. This work is centered on the use of ceramic monoliths as catalyst support to carry on gas-liquid catalyzed reactions. The novelty of this approach consists of feeding the monolith with a froth generated with in the reactor. This method, unlike feeding methods used by other researchers, can be used to feed industrial-size reactors. Once the froth is introduced inside the capillary cells of the ceramic monolith, a bubble-train flow is formed by a sequence of bubbles and small liquid slugs. This setup presents a large gas-liquid and liquid-solid interfacial area and enhances mass transfer between the phases.
In order for the monolith froth reactor to provide the highest possible reaction rate, it is important that mass transfer limitations be minimized. One of the purposes of this research is to investigate the effects of mass transfer inside an ideal monolith channel. a single capillary reactor was developed to create the ideal channel and conduct a series of mass transfer experiments. The partial oxidation of ethanol over a palladium catalyst was used as a model reaction through which mass tranfer can be observed.
Mass Transfer and Chemical Reaction in a Monolithic Foam Reactor, by J. Papa, M. A. Abraham, and R. L. Cerro. Proceedings of the2nd Intern. Congress on Energy, Environmental, and Technological Innovation , 3 , 57, (1992).
The Monolith Froth Reactor: Development of a Novel Three-Phase Catalytic Reactor, by R. Cerro, L.L. Crynes, and M.A. Abraham. AIChE J. , 41 , 337, 1995.
Bubble-Train Flow in Capillaries of Circular and Square Cross Section, by C. Thulasidas, M. A. Abraham, and R. L. Cerro. Chem. Engng. Science , 50 , 183, (1995).
Residence Time Distribution in Three-Phase Monolithic Reactor, by R. H. Patrick, T. Klindera, L. L. Crynes, Ramon L. Cerro and M. A. Abraham. AIChE J. , 41 , 649, 1995.
The Monolith Froth Reactor: Residence Time Modelling and Analysis, by T. C. Thulasidas, Ramon L. Cerro, and M. A. Abraham. Trans. IChemE , 73 , 314, 1995.
How do bubbles enter a capillary?, by de Tezanos Pinto, M., M. A. Abraham, and R. L. Cerro. Chem. Eng. Sci., 52 , 1685, 1997.
Flow Patterns in Liquid Slugs during Bubble-Train Flow Inside Capillaries, by Thulasidas, C., M. A. Abraham, and Ramon L. Cerro Chem. Eng. Sci. , 52 , 2947, 1997.
Influence of Flow Properties on the Performance of the Monolith Froth Reactor for Catalytic Wet Oxidation of Acetic Acid, by A. Klinghoffer, R. L. Cerro, and M. A. Abraham. I&EC Research, 37, 1203-10, 1998.
Catalytic Wet Oxidation of Acetic Acid using Platinum on Alumina Monolith Catalyst, by A. Klinghoffer, R. L. Cerro, and M. A. Abraham. Catalysis Today, 40, 59-72, 1998.
Axial Dispersion in Bubble-Train Flow Inside Capillaries, with C. Thulasidas and M. A. Abraham. Chemical Eng. Sci., 54, 61-76, 1999
Pressure Drop in Monolith Reactors, with P. Woehl. Catalysis Today, 69, 171-174, 2001.
The search for artificial methods for the augmentation of heat transfer rates across heat transfer surfaces has been an area of active research and development work for more than 30 years. The main objective of this research is understanding the fundamentals of flow and heat transfer from internally and externally finned surfaces. The emphasis of this research is on the development of technology and its use for special industrial applications.
A two-component Laser-Doppler Velocimeter from TSI with a 300mW laser is used to determine flow patterns and turbulent spectra around the finned surfaces. The LDV is fiber-optic-based with variable focal length and variable measurement region size. It includes a two-component IFA 650 signal analysis system, an 83mm two-component fiber-optical probe, a ColorBurst Transmitting- Receiving system, and FIND, data analysis software capable of determining velocity and vorticity fields.
Newly developed liquid-crystal technology is used for the visualization of temperature fields around the finned surfaces. Liquid crystals change color at different temperatures. By using a precise amount of heat we are able to have a color/temperature distribution on the surface of the fins and ribs and then use this information to compute local heat transfer coefficients. This technique has given us a very valuable insight on the way fins and ribs work as heat transfer enhancers.
Heat Transfer Performance of Fintubes with Solid versus Serrated Fins, with S. Shetty, H. Mitchell, M de Tezanos Pinto, and F. Papa. Avances en Ingenieria Quimica, 8, 16-23, 1998 (Actually published in 1999).
This research started as a collaboration with the group of the Universidad de Salamanca, leadered by Dr. Miguel A. Galan . Currently, there is a post-doctoral fellow from Salamanca at The University of Tulsa, Dr. Francisco Javier Montes. This research ties very nicely with our research on ordered packings and perforated trays. The idea is to develop a fundamental understanding of how bubbles are formed and how mass transfer occurs during bubble formation. This knowledge is very important to control the concentration of Oxygen in certain types of fermentation reactors
Mass Transfer and Agitation from Bubbles in Fermentation Reactors, by M. A. Galan, F. J. Montes, and R. L. Cerro. Presented at AIChE Annual Meeting 1997. AIChE 1997
Mass Transfer from Oscillating Bubbles in Bioreactors, with F. J. Montes and M. A. Galan, Special issue of ISCRE-15/Chem. Eng. Sci., 54, 3127-3136 1999.
Oscillation Modes and Velocity Profiles near Oscillating Bubbles, by M. A. Galan, F. J. Montes, and R. L. Cerro. Presentation at AIChE Annual Meeting 1998. AIChE 1998
Comparison of theoretical and experimental characteristics of oscillating bubbles, with F. J. Montes and M. A. Galan, Special issue of I&EC Research in honor of Professor W. Schowalter, I&EC Research, 41, 6235-6245, (2002).EMail: email@example.com