The
effects of the chemical structure, surface properties, and
micropore of modified black carbon samples (BCs) on the sorption mechanism
of hydrophobic organic contaminants (HOCs) are discussed. Activated
and oxidized BCs were produced from a shale kerogen at 250–500
°C by chemical activation regents (KOH and ZnCl2)
and then by oxidative regents (H2O2 and NaClO).
The surface properties (water contact angel, Boehm titration, and
cation exchange capacity, CEC), structural properties (advanced solid-state 13C NMR), micropore properties (CO2 adsorption),
mesopore properties (N2 adsorption), and sorption and desorption
properties of phenanthrene were obtained. The results showed that
ZnCl2-activated BCs had higher basic surface groups, CEC
values, aromatic carbon contents, micropore volumes, and adsorption
volumes but exhibited lower acidic surface groups than the KOH-activated
BCs did. Micropore modeling and sorption irreversibility indicated
that the micropore filling was the main sorption mechanism of phenanthrene.
In addition, ZnCl2 activated and NaClO oxidized BCs showed
a nice regression equation between adsorption volumes and micropore
volumes (CO2–V
0) as
follows: Q
0
′ = 0.495V
0 + 6.28(R
2 = 0.98, p < 0.001). Moreover, the contents of nonprotonated aromatic carbon,
micropore volumes, and micropore sizes are the critical factors to
micropore filling mechanism of phenanthrene on BCs. The size of fused
aromatic rings was estimated from the recoupled 1H–13C dipolar dephasing, and the BC structural models at temperatures
ranging from 300 to 500 were proposed. This finding improves our understanding
of the sorption mechanism of HOCs from the perspectives of chemical
structure and micropore properties.