Venkatakrishnan, N. (1975) Studies on periodic precipitation systems in aqueous media. PhD thesis, Madurai-Kamaraj University.

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The phenomenon of the formation of periodic precipitate structure has attracted the attention of several research workers. The usual method of obtaining such structures is to diffuse the external electrolyte into the gel impregnated with internal electrolyte. In this thesis the phenomenon is explained based on diffusion mechanism and the following logarithmic relationship. Log (Xn-Xn-1) = A + α Xn In the present studies six different systems, viz. lead arsenite, lead arsenate, lead carbonate, lead fluoride in aqueous agar agar gel and zinc carbonate and lead carbonate in aqueous polyvinyl alcohol gel. Data obtained for the spacings between the rings has been plotted as log (Xn-Xn-1) against Xn. The curves obtained are straight lines proving the validity of the equation for all the systems. The influence of concentrations of external and internal electrolytes on the spacing of rings is another aspected predicted by the equation. From the general equation; (Xn-Xn-1) = (P(S/CoCo1)) eαXn The distance between the consecutive rings should be inversely proportional to the concentration of extend and internal electrolyte. Detailed studies were also made on the factors influencing the spacings in periodic precipitation with special reference to the effects of anions, acids, gel concentration, addition of glycerol, mixed gels, temperature, electric potential etc. All the above mentioned factors influence the ring spacings by increasing or decreasing the rate of diffusion of ions. The logarithmic relationship is also verified in all these cases. The correctness of the mathematical theory of the formation of periodic precipitation based on diffusion mechanism is proved from the various experimental studies

Item Type: Thesis (PhD)
Uncontrolled Keywords: Periodic precipitation systems
Subjects: Electrodics and Electrocatalysis
Electrochemical Power Sources
Depositing User: Dr. N Meyyappan
Date Deposited: 13 Jun 2012 05:31
Last Modified: 13 Jun 2012 05:31

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