Conclusions
OSP feasibility for water treatment was investigated on batch
and column scales. The OSP exhibited an MB-removal capacity
of ∼2.0mg/g under the equilibrium condition by good fitting
of the Langmuir model. Kinetically the removal followed the
pseudo-first-order reaction, and the MB adsorption onto OSP
was spontaneous. In continuous column tests, two modes,
namely OSP-layer deposition and OSP-entrapped agarose gel
packing, showed different removal mechanisms and capacities.
Furthermore, carbon nanodots-entrapped OSP–agarose
gel showed a colorimetrical gradient at different concentrations
of Mn2+ and Fe3+ ions. As a result, Mn2+ exhibited
a tan brown, but Fe3+ nonetheless became pale brown
after interaction of the carbon nanodots in the OSP–agarose
gel. Although the use of OSP–agarose gel showed better
MB-removal efficiency with multi-functionalities, agarose
recycling is additionally warranted. Both OSP and OSP–MB
have a bacteria-biocompatible matrix. Thus, for advanced
water treatment applications, approaches entailing the incorporation
of unique metal oxides into OSP can be suggested for
the killing of pathogen bacteria.