Colloid Systems

In the article the equations of a kinetics of coagulation of disperse systems and theory of a solvate layer of colloidal particles are given. 1. KINETIC EQUATION of COAGULATION The particles of colloids and suspensions in relation to molecules are macroobjects, and in matching with customary macroobjects have the microscopic sizes, i.e. take an intermediate standing in scale hierarchy. At the same time they have the particular properties, usage which one is important for a biology and technology. All living organisms as a matter of fact represent colloid systems. I shall remind, as the colloid particle (or larger particle of suspension), shown on a figure 1 is arranged. On a figure 1: 1 colloid particle, 2 – potentialdefining ions, adsorbed on a surface of a particle, 3 solvate layer of oriented dipoles (molecules of water) thick several hundreds molecules, 4 sliding surface in a disperse medium, 5 counterions. At a Brownian motion of a particle, if it is not enough of counterions, they have no time compensate electric charge of potentialdefining ions, therefore particle has some electric potential ς (zeta-potential). The zeta-potential stipulates stability to sticking (coagulation) of colloid particles. If in a disperse medium there will be a sufficient amount of counterions, ς potential is reduced and there is a coagulation. The colloid particles stick together among themselves, but the electric charge them thus practically does not vary, because of what they can not form uniform large aggregate. Therefore in the kinetic equation Smoluhovsky it is necessary to allow for equilibrium calculating concentration of aggregates C∞. The value C∞ is bound, on the one hand, to a coulomb repulsion of particles component aggregate, on the other hand, this value depends on an adhesive strength of particles in aggregate, which one depends on a state of a solvate layer. Accepting, on Smoluhovsky, the second order for a kinetics of sticking of particles taking into account of equilibrium calculating concentration, it is possible to record: ( ) dC K C C dτ ∞ − = − (1), where C current concentration of particles, 1/cm. The solution of the equation (1) it is possible to present as follows: 1