Polymer flocculation
technology has a very broad application in
the flocculation industry of oil sand tailings at present. Nevertheless,
the most commonly used commercial polyacrylamide flocculant has problems
of low flocculation efficiency and secondary pollution. In this paper,
we proposed an organic–inorganic composite flocculant with
self-degrading properties for the flocculation treatment of oil sand
tailings, which was prepared by a photocatalytic surface initiation
technique. Further, the functional groups of the materials before
and after polymerization composites were characterized by infrared
spectrum to explore the polymerization mechanism, the structure was
observed by transmission electron microscope, and the molecular weight
of polyacrylamide was measured by gel permeation chromatography. Then,
the flocculation performance was characterized by the flocculation
experiment (tested with simulated oil sand tailings). Subsequently,
the flocculation mechanism was explored by testing the zeta potential
of the organic–inorganic composites and analyzing images of
sediment observed by transmission electron microscope and atomic force
microscope. Finally, the test of self-degradation performance was
carried out under illumination. On the basis of the above experiments,
the following conclusions were obtained. First, the structural characterization
results indicate the polymerization mechanism is that, under the condition
of light, the surface of the inorganic photocatalyst generates free
radicals to initiate the radical polymerization of the monomers, so
that the monomers successfully grow on the surface of the inorganic
particles into a comb structure. And then, the flocculation experiment
shows that reduced graphene oxide/titanium dioxide-polyacrylamide
(2:40) has the best flocculation effect, of which the supernatant
transmittance is 21.4 higher and the sedimentation ratio is 8.9% higher
than those of the commercial polyacrylamide. The reason for its excellent
flocculation performance is that the zeta potential of the organic–inorganic
composite increases, reducing repulsion of particles and flocculant
molecules; simultaneously, the formed comb structure is beneficial
to the expansion of the polymer chain and increases the contact area,
thereby improving the flocculation effect. Ultimately, the degradation
results indicate that the new organic–inorganic composite had
good degradation effect, with the degradation rate up to 75.9% within
4 h. Therefore, this work has made great contributions to solving
the oil sand tailings pollution field.
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