Forces between fully hydroxalated silica surfaces were measured using an atomic force microscope. The measurements were conducted in Nanopure water and in solutions containing various organic solutes such as methanol, ethanol, trifluoroethanol (TFE), and pyridine. The results obtained in Nanopure water showed a strong short-range repulsive force at distances below 15 nm. This non-DLVO force can...

Protein coated particles present an anomalous colloidal stability at high ionic strength when the classical theory (DLVO) predicts aggregation. This observed deviation from DLVO behaviour appears for electrolyte concentrations above some critical bulk value. As we have suggested in previous publications the existence of an additional short-range repulsive 'hydration force' due to specific hydra...

The notion of »non-equilibrium surface forces« is advanced for the application in a number of cases of colloid stability and transport phenomena. The idealized concept of full equilibrium in the double layer, as used in the DLVO theory is shown to be too simple to describe the stability of a colloid particle not in equilibrium with the surround ing medium. Cases are described where surface forc...

In the midst of the second world war, Derjaguin and Landau in Russia and Verwey and Overbeek in The Netherlands arrived independently at a theory to explain the kinetic stability of colloidal dispersions. The celebrated DLVO theory combined two types of forceslong-ranged electrostatic repulsion and short-ranged van der Waals attractionto predict the rates at which nanoand microparticles aggre...

The role of extracellular macromolecules on Escherichia coli O157:H7 transport and retention was investigated in saturated porous media. To compare the relative transport and retention of E. coli cells that are macromolecule rich and deficient, macromolecules were partially cleaved using a proteolytic enzyme. Characterization of bacterial cell surfaces, cell aggregation, and experiments in a pa...

Abstract—Surface characteristics of Bacillus megaterium strain were investigated; zeta potential, FTIR and contact angle were measured. Surface energy components including Lifshitz-van der Waals, Hamaker constant, and acid/base components (Lewis acid/Lewis base) were calculated from the contact angle data. The results showed that the microbial cells were negatively charged over all pH regions w...

The adhesion kinetics of Burkholderia cepacia G4g and ENV435g have been investigated in a radial stagnation point flow (RSPF) system under well-controlled hydrodynamics and solution chemistry. The sensitivity of adhesion behavior to nutrient condition was also examined. Supplementary cell characterization techniques were conducted to evaluate the viability, hydrophobicity, electrophoretic mobil...

The goal of this paper is to focus on the effect of fluid flow, solution chemistry and surface morphology of fibrous media (in terms of roughness and charge heterogeneity) on colloid removal. A theoretical framework on the role of flow velocity on particle deposition to cylindrical substrate is presented. Existing theories related to particle attachment onto cylindrical substrates and on the ef...

The nature of the physical interactions between Escherichia coli JM109 and a model surface (silicon nitride) was investigated in water via atomic force microscopy (AFM). AFM force measurements on bacteria can represent the combined effects of van der Waals and electrostatic forces, hydrogen bonding, steric interactions, and perhaps ligand-receptor type bonds. It can be difficult to decouple the...