Reaction Limited Aggregation RLA

To produce such aggregates, a solution of hematite was prepared (with a well ultrasonified colloid sol), the solution chemistry adjusted to the desired values and salt added. This solution was left to aggregate overnight in a 2 L container and stirred at 270 rpm. Most experiments were carried out at pH 3 at various KCl concentrations. 

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Let us illustrate first how different (idealized) aggregation processes may result in different structures. There is extensive literature on diffusion-limited aggregation (DLA) (for a comprehensive review, see Meakin, 1988). Three methods of simulation are common (standard) diffusion-limited aggregation (DLA), reaction-limited aggregation (RLA), and linear trajectory aggregation (LTA). DLA structures are generated by placing a seed particle in the middle of a lattice. Other particles are placed in the lattice... 

The total volume fraction, 7 ( ), as a function of time for both reaction limited aggregation (RLA) and diffusion limited aggregation (DLA)... 

For very large stability ratios, where only a tiny fraction of collisions between particles result in a stable bond, the process is termed reaction limited aggregation (RLA). 

Diffusion-limited aggregation (DLA) is often referred to as a fast process because the above model predicts the maximum aggregation rate. Reaction-limited aggregation (RLA) rates are slower than predicted by the DLA model. The effect of the slow attachment reaction rate on the aggregation rate is expressed as a stability ratio (W) and is defined as the ratio of the Smoluchowski rate constant (ks) to the observed rate constant (ko). 

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