Adsorption Thermodynamics and Kinetics of Nanomaterials at Interfaces

Abstract

Investigations on the adsorption dynamics or interactions of nanomaterials at interfaces have enabled applying nanotechnologies in current industrial systems effectively. In this work, enhanced oil recovery (EOR) and impacts of nanoparticles on environment are energy-related and environmental-related systems investigated respectively. Amphiphilic materials were investigated at liquid-liquid and liquid-solid interfaces in the EOR system. Dynamics of asphalt recovery using surfactant floods was studied using quartz crystal microbalance with dissipation (QCM-D) and a promising mobility control approach that could replace current methods was proposed.

The kinetic model of asphalt (heavy oil) recovery via surfactant flooding is related to a fast removal process of large microemulsions and a slow removal process of loaded micelles at interfaces of the asphalt film and the surfactant solution. Effective type of surfactant and the concentration range of surfactant flooding useful for the asphalt recovery were also found.

One novel system was developed based on the complexation and supramolecular assembly of amino-amide type amphiphiles and maleic acid to change viscosity of aqueous displacement fluids for mobility control in EOR. It was shown that the addition of only 2 wt. % of adaptable amphiphiles/maleic acid into water increased the viscosity of water by 4.5x10^5 times. This superior viscosity behavior was ascribed to the formation and entanglements of layered cylindrical supramolecular assemblies having diameters of several hundred nanometers. Furthermore, the viscosity of the amphiphile solution could be changed in a reversible manner by changing pH with no obvious degradation. Sand column displacement experiments were carried out with different process variables for future pilot applications.

Polymeric nanomedicines were studied at liquid-solid interfaces in the environmental-related system. Deposition trends of various polymeric nanomedicines were investigated in environmental related media for wastewater control in hospitals or pharmaceutical manufacturers. Adsorption dynamics and transportation behaviors through porous media were studied considering the effect of surface chemistries of polymeric nanomedicines. The mobility of negatively charged nanoparticles is strongly dependent on the amount and types of salts in solutions. With the presence of calcium ions, even at low ionic strengths (i.e. 10mM), induced adsorption appeared on silica surfaces and strongly limited the mobility of polymeric nanomedicines.