lower solute concentrations; Fig. 1a and d) and the appearance of
the cooperative-like uptake (Fig. 1c and e) seem to be induced by
the added OM. These changes could be associated with the presence
of flexible aliphatic components and oil residues in the
OMW that may more readily swell and accommodate sorbed
organic compounds. The possibility that sorbate-induced changes
in a soil–sorbent matrix might be a reason for sorption cooperativity
is supported by the above-mentioned observation of strong desorption
hysteresis for all of the sorbate–soil systems where it was
tested. This indicates a resistance of the organic compounds to
being released from a sorbed state to aqueous solutions. The
biodegradation of simazine and diuron in the batch sorption experiments
carried out at the presence of a biocide (see Section 2) is not
expected. Also, based on examining the controls containing a
solute (without a sorbent) and NaN3 (at the presence of 0.01 M
CaCl2), no reactions between sodium azide and organic solutes
were anticipated. In addition, the desorption resistance was
observed for two compounds belonging to essentially different
chemical classes, i.e., triazines and ureas, with different chemical
reactivity, that typically do not undergo biotic and abiotic degradation
for time periods much longer than that of the current experiment
(TOXNET-HSDB, 2015). Therefore, ‘‘an irreversible swelling’’
(Braida et al., 2003) of soil components by sorbed simazine and
diuron could contribute to desorption resistance and cooperative
sorption uptake.
4. Conclusions
lower solute concentrations; Fig. 1a and d) and the appearance ofthe cooperative-like uptake (Fig. 1c and e) seem to be induced bythe added OM. These changes could be associated with the presenceof flexible aliphatic components and oil residues in theOMW that may more readily swell and accommodate sorbedorganic compounds. The possibility that sorbate-induced changesin a soil–sorbent matrix might be a reason for sorption cooperativityis supported by the above-mentioned observation of strong desorptionhysteresis for all of the sorbate–soil systems where it wastested. This indicates a resistance of the organic compounds tobeing released from a sorbed state to aqueous solutions. Thebiodegradation of simazine and diuron in the batch sorption experimentscarried out at the presence of a biocide (see Section 2) is notexpected. Also, based on examining the controls containing asolute (without a sorbent) and NaN3 (at the presence of 0.01 MCaCl2), no reactions between sodium azide and organic soluteswere anticipated. In addition, the desorption resistance wasobserved for two compounds belonging to essentially differentchemical classes, i.e., triazines and ureas, with different chemicalreactivity, that typically do not undergo biotic and abiotic degradationfor time periods much longer than that of the current experiment(TOXNET-HSDB, 2015). Therefore, ‘‘an irreversible swelling’’(Braida et al., 2003) of soil components by sorbed simazine and
diuron could contribute to desorption resistance and cooperative
sorption uptake.
4. Conclusions
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