Structure formation during precipitation reaction in gels new liesegang patterns

Article abstract of DOI:10.1002/bbpc.19981021132

The paper reports on an investigation carried out into one- to three-dimensional Liesegang systems (test tub: arrangement) composed of different concentrations of lead nitrate in Agar gel wilh either potassium iodide or potassium dichromate as the precipitation reagent. A rich variety of different structure formulions, including screw formations of the weakly soluble reaction product is documented. Measurements of the progression of the precipitation front show a dependence of the diffusion path on time that which deviates from the Einstein-Smoiuchowski root mean square displacement. The measured exponent n of the displacement xⁿ=f(t) is discussed in detail and interpreted as the dynamic dimension d_w of the diffusion through the fractal medium of the gel, the backhone dimension of which couid be estimated. A cellular automaton model is used to describe the DLA cluster formation of the precipitate as well as the geometrical shape of the Liesegang patterns. WTLEY-VCH Verlag GmbH, 1998.