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Developing Polycation-Clay Sorbents for Efficient Filtration of Diclofenac: Effect of Dissolved Organic Matter and Comparison to Activated Carbon
journal contribution
posted on 2015-08-04, 00:00 authored by Hagay Kohay, Avital Izbitski, Yael G. MishaelThe
presence of nanoconcentrations of persistent pharmaceuticals
in treated wastewater effluent and in surface water has been frequently
reported. A novel organic–inorganic hybrid sorbent based on
adsorbing quarternized poly vinylpyridinium-co-styrene
(QPVPcS) to montmorillonite (MMT) was designed for the removal of
the anionic micropollutants. QPVPcS-clay composites were characterized
by X-ray diffraction, FTIR, thermal gravimetric analysis, Zeta potential
and element analysis. Based on these measurements polymer–clay
micro- and nanostructures, as a function of polymer loading, were
suggested. The affinity of the anionic pharmaceutical, diclofenac
(DCF), to the composite was high and did not decrease dramatically
with an increase of ionic strength, indicating that the interactions
are not only electrostatic. The presence of humic acid (HA) did not
hinder DCF removal by the composite; whereas, its filtration by granulated
activated carbon (GAC) was compromised in the presence of HA. The
kinetics and adsorption at equilibrium of DCF to the composite and
to GAC were measured and modeled by the time dependent Langmuir equation.
The adsorption of DCF to the composite was significantly faster than
to GAC. Accordingly, the filtration of micro- and nanoconcentrations
of DCF by composite columns, in the presence of HA, was more efficient
than by GAC columns.