Coagulation of particles

Adsorption on Kaolinite. As for polyacrylamides, adsorption of XCPS on kaolinite is conducted as a function of S/L and the results extrapolated to S/L=0. However, the S/L dependence of XCPS adsorption on kaolinite is considerably less than that for HPAM. This is due to the flat conformation of the adsorbed molecules of semirigid xanthan (25) compared to the more extended conformation of flexible HPAM (27). The absence of loops and tails in the adsorbed XCPS layer thus diminishes the probability of flocculation of particles by polymer bridging. The slight dependence in adsorption on S/L may therefore be attributed to coagulation of particles induced by Ca. ... 

The rate of coagulation of particles in a liquid depends on the frequency of collisions between particles due to their relative motion. When this motion is due to Brownian movement coagulation is termed perikinetic when the relative motion is caused by velocity gradients coagulation is termed orthokinetic. 

Condensation of reaction products or water on particles from (1) or coagulation of particles from (1) 0.08-0.37 0.16 2.05... 

Let us now consider coagulation of particles in the absence of any repulsive barrier. In addition, we assume that, although there are no interparticle forces that contribute to the transport of particles toward each other, there is sufficient attraction between the particles on contact for them to form a permanent bond. As early as 1917, Smoluchowski formulated the equations for the collision rate for particles transported by diffusion alone (Smoluchowski 1917), and we develop the same idea here. 

The accumulation mode (0.1 < d ic < 1pm) particles included in this mode originate from coagulation of particles in the nucleation mode and from condensation of vapors onto existing particles. These particles usually accounts for a substantial part of the aerosol mass and for most of the aerosol surface area (Seinfeld and Pandis, 1998). 

Baxendale, Evans and coworkers reported in 1946 that the polymerization of methyl methacrylate (MMA) in aqueous solution was characterized by homogeneous solution kinetics, i.e. where mutual termination of free radicals occurred, in spite of the fact that the polymer precipitated as a separate phase. Increases in the rates of polymerization upon the addition of the surfactant cetyl trimethyl ammonium bromide (CTAB) were attributed to the retardation of the rate of coagulation of particles, which was manifested in a reduction in the effective rate constant for mutual termination,... 

Gibbs, R.J. (1983) Effect of natural organic coatings on the coagulation of particles. Environ. Sci. Technol., 17, 237-240. 

Wet scrubbing uses liquid droplets to remove fine dust in a gas stream. In all types of wet scrubbing, the basic cleaning mechanism involves the attachment of particles to the droplets. The function of the droplets in scrubbers is similar to that of spherical fibers in filtration. Likewise, the primary collection mechanisms in scrubbing are similar to those in filtration, i.e., inertial impaction, interception, and diffusion [e.g., Fan, 1989]. Secondary collection mechanisms include thermophoresis due to temperature gradients, coagulation of particles due to particle electrification, and particle growth due to liquid condensation. 

The process of sedimentation in which the settling of suspended particles results in a dense compaction, or coagulation, of particles in which liquid is squeezed out. Geologically, significant compaction of clay layers caused by lowering of the water table (dewatering). 

This problem is encountered in the theory of coagulation of particles in sonic fields. 

The rate of coagulation, of particles of mass mp is equal to the net rate of flow of particles of reduced mass mT across the sphere of influence of radius Rs, i.e.,... 

For the case of coagulation of particles of two different sizes, it is possible to follow the same approach as given for the monodisperse case except that d is replaced with + d2)/2 and 2D is replaced with Dt + D2. Then the coagulation coefficient Kl2 becomes... 

The second term of this equation represents the loss of particles in the volume size range v + dv resulting from coagulation of particles of volume v and volume . The term K(v, ) is the combined coagulation coefficient for tljese two particles. Thus this equation gives an expression for the net rate of change of particles whose volumes lie between v and v + dv. Solution of the equation with appropriate initial conditions gives the number of particles of volume v + dv at any time t. 

Ordered coagulation of particles of approximately the same size. For... 

Examination of thick sulfur-extended binder films, mixed with sulfur for 30,45, and 60 sec, showed the presence of some larger sulfur particles. As the particle density on the slide is higher in thick films, this demonstrates that some coagulation of the sulfur particles takes place if the sulfur content is too great, relative to the amount of asphalt (sulfur/ asphalt weight ratio, 0.33). Similar evidence of coagulation of particles was obtained in thick films taken from the laboratory Waring blender dispersion for a similar blend. 

Not always does the lowest particle size provide the best results. The decreased detector response obtained from a particle size < 36 pm relative to < 50 and < 77 pm was ascribed to the increased co-extraction of interferents with the anaiyte for sediments [16] or to the coagulation of particles in the case of plant material [17],... 

Ibid., ii, 222. Boerhaave seems to contradict himself in this instance, for in his chapter on pure fire, he had argued that the effect of fire upon the particles of bodies is the loosening of bodies, rather than the coagulating of particles. 

Aerosol concentrations and size distributions can be investigated remotely using sun-photometry. Characterization of volcanic aerosol is important in smdies of plume chemistry, atmospheric radiation, and the environmental and health impacts of particle emissions. Watson and Oppenheimer (2000, 2001) used a portable sun-photometer to observe tropospheric aerosol emitted by Mt. Etna. They found distinct aerosol optical signatures for the several plumes emitted from Etna s different summit craters, and apparent coagulation of particles as the plume aged. More recently. Porter et al. (2002) have obtained sun-photometer and pulsed lidar data for the plume from Pu u O o vent on Kilauea, Hawaii, from a moving vehicle in order to build profiles of sulfate concentration. 

Figure 4. Residence time of particles in seconds (left axis) and days (right axis) as a function of particle radius. The shaded areas represent estimates of the lifetimes made as follows 1, molecular or ionic clusters C, coagulation of particles P, removal by precipitation F, gravitational settling A, derived from spatial distribution of Aitken particles R, derived from the distribution of small radioactive particles. From Kreidenweis et al. (1999) in Atmospheric Chemistry and Global Change by Brassem et al. 1999 by Oxford University Press, Inc. Used by permission.

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