Colloid mobilization and transport in groundwater

In this review, initial microbial adhesive interactions are divided into adhesion to substratum surfaces, coaggregation between microbial pairs and co-adhesion between sessile and planktonic microorganisms of different strains or species. The physico-chemical mechanisms underlying the adhesive interactions are described and a critical review is given of currently employed methods to study microbial adhesive interactions, with an emphasis on the use of the parallel plate flow chamber. Subsequently, for each of the three microbial adhesive interactions distinguished, the role of Lifshitz-van der Waals, acid-base and electrostatic interactions is described based on existing literature.

Physico-chemistry of initial microbial adhesive interactions – its mechanisms and methods for study

Mechanism of Cationic Surfactant Adsorption at the Solid-aqueous Interface

Kinetics of localized adsorption of colloid particles

Kinetics of polymer adsorption in stagnation point flow.

An experimental technique has been developed to study the deposition of colloidal particles under well controlled hydrodynamic conditions. The deposition process is observed under a microscope and recorded on video tape for further analysis. Fluid flow conditions in the experimental set-up were determined by numerical solution of the Navier-Stokes equations. Mass transfer equations were solved numerically (taking into account hydrodynamic, gravitational, electric double layer, and dispersion forces) for the stagnation point region. Also, some analytical solutions are presented. Deposition has been studied of 0.5μm polystyrene latex particles on cover glass slides used as collectors. From an analysis of the shape of the coating density vs. time curves and independently from the distribution of the particles on collector surfaces, it was found that one particle is able to block an area of about 20 to 30 times its geometrical cross-section. The initial flux of particles to the collector for a given salt concentration was found to depend strongly on the method of cleaning the collector surface. In general the flux and the escape of particles to and from the collector surface are sensitive to the interaction energy at small separations. The direct method of observing particle deposition and detachment could lead to important insights into the nature of particle-wall interactions at near contact.

A direct method for studying particle deposition onto solid surfaces

The kinetics of coating of solid walls (collectors) by colloidal particles has been studied theoretically and experimentally taking into account the influence of (i) the time dependence of the escape rate (aging), (ii) the already deposited particles (blocking or masking effects), and (iii) the coagulation of the colloidal particles prior to deposition. A detailed discussion is presented of the escape velocity due to the thermal motion of the particles and of the influence of hydrodynamic forces, especially under turbulent flow conditions. It is shown that particle detachment, masking, and coagulation cause deviation from the linear relationship between coating density and time. Experimental data obtained from a direct visual observation of the deposition process are interpreted on the basis of the presented theory.

T Da̧broś

Papers

A direct method for studying particle deposition onto solid surfaces

Kinetics of coating by colloidal particles

Surface collisions in a viscous fluid

NoteFlexible bonds between latex particles and solid surfaces

On the effects of blocking and particle detachment on coating kinetics