Dynamic light scattering from power-law polydisperse fractals: Application of dynamic scaling to humic acid

1996 ◽  
Vol 53 (3) ◽  
pp. 2980-2983 ◽  
Author(s):  
S. Z. Ren ◽  
E. Tombácz ◽  
James A. Rice
Keyword(s):  
Light Scattering ◽  
Humic Acid ◽  
Dynamic Light Scattering ◽  
Power Law ◽  
Dynamic Scaling

scholarly journals Temperature Induced Aggregation and Clouding in Humic Acid Solutions

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Leah Shaffer ◽  
Ray von Wandruszka
Keyword(s):  
Aqueous Solution ◽  
Light Scattering ◽  
Humic Acid ◽  
Dynamic Light Scattering ◽  
Acid Solutions ◽  
Inverse Temperature ◽  
Mechanical Agitation ◽  
Coulombic Repulsion ◽  
Polarity Sensitive ◽  
Induced Aggregation

Humic acids in aqueous solution demonstrate inverse temperature-solubility relationships when solution conditions are manipulated to reduce coulombic repulsion among the humic polyanions. These effects were followed by dynamic light scattering (DLS) measurements of the resulting aggregates, as well as the addition of a polarity sensitive fluorescent probe (pyrene). The humic solutions could be primed for temperature induced clouding by carefully lowering the pH to a point where hydration effects became dominant. The exact value of the cloud point (CP) was a function of both pH and humate concentration. The CPs mostly lay in the range 50–90°C, but DLS showed that temperature induced aggregation proceeded from approximately 30°C onward. Similar effects could be achieved by adding multivalent cations at concentrations below those which cause spontaneous precipitation. The declouding of clouded humate solutions could be affected by lowering the temperature combined with mechanical agitation to disentangle the humic polymers.

Soil humic acid aggregation by dynamic light scattering and laser Doppler electrophoresis

2013 ◽  
Vol 176 (5) ◽  
pp. 674-679 ◽  
Author(s):  
Uroš D. Jovanović ◽  
Mirjana M. Marković ◽  
Svjetlana B. Cupać ◽  
Zorica P. Tomić
Keyword(s):  
Light Scattering ◽  
Humic Acid ◽  
Dynamic Light Scattering ◽  
Laser Doppler ◽  
Soil Humic Acid ◽  
Laser Doppler Electrophoresis

Light-scattering studies of aggregation

1989 ◽  
Vol 423 (1864) ◽  
pp. 89-102 ◽  
Keyword(s):  
Fractal Dimension ◽  
Light Scattering ◽  
Dynamic Light Scattering ◽  
Power Law ◽  
Fractal Geometry ◽  
Linear Growth ◽  
Fractal Dimensions ◽  
Power Law Model ◽  
Aggregate Distribution ◽  
Scattering Measurements

We discuss dynamic and static light-scattering measurements made during slow (reaction-limited) aggregation of model colloids and immune complex forming proteins. Analysis of the results leads to an understanding of the random aggregates formed in terms of a fractal geometry and measurement of the fractal dimension. Differences in the measured fractal dimensions of the model and protein systems are discussed. The aggregation appears to follow ‘Smoluchowski-like’ kinetics as measured by a near linear growth of the low-angle light scattering with time. However, the dynamic light-scattering results support a simple power-law model for the aggregate distribution and allow an estimate of this power law to be made.

Dynamic light scattering from gels in a poor solvent

1978 ◽  
Vol 39 (9) ◽  
pp. 955-960 ◽  
Author(s):  
E. Geissler ◽  
A.M. Hecht
Keyword(s):  
Light Scattering ◽  
Dynamic Light Scattering ◽  
Poor Solvent
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