Owing to the significant technological implications of nanoscale colloidal suspensions (nanofluids), it is necessary to develop suitable techniques to characterize the nanostructured aggregates in suspension. In the present work, a fractal dimension approach is applied to characterize the agglomerate structure using image analysis by scanning electron microscope photographs of the nanoparticle aggregates. Aqueous suspensions of aluminum oxide nanoparticles (nanofluids) are used for the study. A simple and direct method of projected image manipulation has been used to calculate the aggregate fractal dimensions in colloidal nanofluid. The fractal dimension provides quantitative information about important morphological features of the aggregate structure. A functional relationship is established between the two-dimensional fractal dimension (df2) and the three-dimensional fractal dimension (df3). The present study demonstrates that the optical image analysis technique can be effectively used for fractal dimension analysis of colloidal nanoparticle aggregates.
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