Fractal dimension of humic acids

✍ Scribed by R. Österberg; K. Mortensen

• Publisher: Springer
• Year: 1992
• Tongue: English
• Weight: 472 KB
• Volume: 21
• Category: Article
• ISSN: 1432-1017
• DOI: 10.1007/bf00196759

✦ Synopsis

Small-angle neutron scattering experiments have been made on solutions of humic acid aggregates with an acidity corresponding to pH 5.0 and at 0.1 M ionic strength. We observe power-law decay of the intensity over one decade of the scattering vector, Q, indicating that the aggregates are fractal. We explain the normalized intensity in the entire Q-range by assuming that the humic acid particles can be described by building units of a radial size, < 25 ~, aggregated into clusters with an average radius of 400-500 ~. For humic acids obtained from two different sources, we determine the fractal dimension, D = 2.3 4-0.1. For small values of Q, the measured data of one of the samples extend into the Guinier range giving an average radius of gyration of 320 + 20 ~.