A light-weight granular mixed-quartz sand (denoted as L-GQS) combined with stirring-assisted
bubble column reactor was firstly applied in catalytic ozonation of atrazine. The
L-GQS, with a density of 2.36 g cm-3 and average diameter of ca. of 4 mm, was readily
churned up and uniformly distributed within the solution in the reactor. The introduction
of L-GQS was found to exhibit enhanced catalytic ozonation of atrazine, with the increase
in degradation rate and the dissolved organic carbon (DOC) removal being more than
2-fold for the catalytic process (L-GQS dosage = 5 g L-1, [atrazine]0 = 50 μM, [O3] = 25 mg L-1,
gas flow = 0.2 L min-1, at pH 7.0 and 293 K). The L-GQS settled at the bottom of the
reactor after experimentation, allowing its easy separation from the solution. A complete
characterization of the material (XRD, XPS, FTIR, FE-SEM/EDS, BET and pHpzc) revealed
that L-GQS consisted of α-quartz, β-cristobalite, anorthoclase and small amount of
iron oxy-hydroxides. Hydroxyl groups, Bronsted acid sites and Lewis acid sites on
the surface of L-GQS all contributed to the atrazine adsorption, ozone decomposition
and ·OH generation. The L-GQS catalyzed ozonation exhibited superior atrazine degradation
and mineralization rates in a wide range of pH (3.0-9.0) and reaction temperatures
(278 K-293 K). Also, an enhancement of DOC abatement was observed both in presence
of natural organic matter isolates and natural water matrices (river water) when L-GQS
was used. Finally, the degradation mechanism was proposed, based on the intermediates
and by-products formation analyzed by LC-QTOF-MS/MS and ionic chromatography. Our
results indicate that the L-GQS combined with stirring-assisted bubble column reactor
could be utilized as an enhancement of ozone-based advanced oxidation processes.