es304075j_si_001.pdf (863.6 kB)
Role of Collector Alternating Charged Patches on Transport of Cryptosporidium parvum Oocysts in a Patchwise Charged Heterogeneous Micromodel
journal contribution
posted on 2013-03-19, 00:00 authored by Yuanyuan Liu, Changyong Zhang, Dehong Hu, Mark S. Kuhlenschmidt, Theresa B. Kuhlenschmidt, Steven E. Mylon, Rong Kong, Rohit Bhargava, Thanh H. NguyenThe
role of collector surface charge heterogeneity on transport
of Cryptosporidium parvum oocyst and carboxylate
microsphere in 2-dimensional micromodels was studied. The cylindrical
silica collectors within the micromodels were coated with 0, 10, 20,
50, and 100% Fe2O3 patches. The experimental
values of average removal efficiencies (η) of the Fe2O3 patches and on the entire collectors were determined.
In the presence of significant (>3500 kT) Derjaguin–Landau–Verwey–Overbeek
(DLVO) energy barrier between the microspheres and the silica collectors
at pH 5.8 and 8.1, η determined for Fe2O3 patches on the heterogeneous collectors were significantly less
(p < 0.05, t test) than those
obtained for collectors coated entirely with Fe2O3. However, η calculated for Fe2O3 patches
for microspheres at pH 4.4 and for oocysts at pH 5.8 and 8.1, where
the DLVO energy barrier was relatively small (ca. 200–360 kT),
were significantly greater (p < 0.05, t test) than those for the collectors coated entirely with
Fe2O3. The dependence of η for Fe2O3 patches on the DLVO energy barrier indicated
the importance of periodic favorable and unfavorable electrostatic
interactions between colloids and collectors with alternating Fe2O3 and silica patches. Differences between experimentally
determined overall η for charged heterogeneous collectors and
those predicted by a patchwise geochemical heterogeneous model were
observed. These differences can be explained by the model’s
lack of consideration for the spatial distribution of charge heterogeneity
on the collector surface.