Effect of Sodium Ion on Synthetic Water-stable Aggregates1
- Andrew P. Mazurak2
Particles of diameter <0.15µ were separated from Hesperia sandy loam (micaceous soil) and electrodialyzed. Proper quantities of 0.1 N NaOH were added to the electrodialzed suspensions so that the symmetry-concentrations, S, of Na+ were 0.0625, 0.125, 0.25, 0.50, 1.0, and 2.0. Each suspension was dried to induce aggregation. The dry synthetic aggregates were then analyzed for their water-stability by shaking them in water for 2-, 20-, 200-, and 2,000-minutes. After each shaking period a size distribution of aggregates was obtained.
The cumulative weight percentage curves for aggregates with Na+ showed two distinct types of size distribution. Those for aggregates formed with electrodialyzed particles and with Na+ of 0.25-S and less showed a sigmoid type of size distribution, while those for aggregates formed with Na+ of 0.50-, 1.0-, and 2.0-S showed a bimodal type. The aggregates formed with electrodialyzed particles were more stable in water than any of the aggregates with Na+. The order of water-stability of aggregates for each of the four shaking periods, as shown by the geometric mean diameters, was: electrodialyzed particles > 0.0625-S Na+ > 0.125-S Na+ > 0.25-S Na+ > 0.50-S Na+ > 1.0-S Na+ > 2.0-S Na+.
The effect of Na+ on the values of geometric mean diameter of water-stable aggregates was not a linear function, but rather some power function.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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