This study indicated that spent diatomaceous earth
from wine processing could be used as a precursor for
the preparation of porous clay adsorbent. The results
showed that the novel adsorbent (base-activated clay
mineral from spent diatomaceous earth) had a larger
adsorption capacity at a higher pH value over the range
of 3–11 and at lower temperature. The adsorption kinetics
were well described by the pseudo-second-order
model equation. Furthermore, the Freundlich model appeared
to fit the data better than the Langmuir model
for describing the adsorption behavior of paraquat from
an aqueous solution on spent diatomaceous earth and
its activated product.