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DLVO Approach to the Flocculability of a Photosynthetic H2-Producing Bacterium, Rhodopseudomonas acidophila
journal contribution
posted on 2007-07-01, 00:00 authored by Xiao-Meng Liu, Guo-Ping Sheng, Han-Qing YuThe DLVO theory was used to explore the flocculation
characteristics of a H2-producing photosynthetic bacterium,
Rhodopseudomonas acidophila. The relationship between
the surface characteristics of this strain and its flocculability
was evaluated. Its flocculability was governed by both
electrolyte concentration and pH, and the appropriate
electrolyte concentration and pH were found to be 0.1 M
NaCl solution and pH 7.0, respectively. In addition, the
extracellular polymeric substances produced by R. acidophila
were observed to have a significant effect on its
flocculation. The effective Hamaker constant between R.
acidophila and water was only 2.27 × 10-23 J, suggesting
that the contribution of van der Waals interaction energy
to the total interaction energy could be neglected. As a
result, the bacterial particles could not overcome the total
energy barrier to flocculate effectively. Otherwise,
because the repulsive total interfacial free energy between
the bacterial cells and water was positive, the cell
particles of R. acidophila repelled each other, resulting in
a great stability of the cell suspensions.