where qe is the equilibrium adsorption capacity (mg g−1 ), Ce is the equilibrium MTBE concentration (mg l−1 ), and KD (l g−1 ) is the par- tition coefficient, respectively.
The isotherm parameters obtained are summarized in Table 3. The adsorption behaviors of MTBE onto the postcrosslinked poly- mer are different from those of the chloromethylated polymer and nonpolar porous polymer. The kinetic diameter of MTBE is reported to be 0.62nm [37]. Li et al. studied the adsorption of aqueous MTBE onto activated carbon fibers (ACFs) and proposed that the adsorption capacity of ACFs for MTBE was correlated to the pore volume of micropores with pore widths of 0.8–1.1nm, which was corresponding to 1.3–1.8 times as wide as the kinetic diameter of MTBE molecule [9]. N2 adsorption results showed that the chloromethylated polymer contained a small BET surface area of 35.8 m2 g−1 without any micropore volume detected. In addi- tion, the average pore width of the chloromethylated polymer is 16.7 nm, approximately 25 times larger than the kinetic diameter of MTBE. This suggests that the chloromethylated polymer is not an appropriate adsorbent for MTBE, evidenced by the fact that MTBE adsorption capacity was markedly lower compared to the other two polymers. In contrast, the postcrosslinking reaction led to the generation of a micropore-dominant structure as well as signifi- cantly increased specific surface area. Note that micropore width of the postcrosslinked polymer is concentrated in the range from 1 to 2 nm. This clearly points out that MTBE molecules can be feasibly adsorbed in the micropores of the postcrosslinked polymer, which is in good agreement with the adsorption data.
The nonpolar porous polymer has the micropore volume of 0.28 cm3 g−1 and surface area of 656.4 m2 g−1 , which is comparable to the postcrosslinked polymer. Nevertheless, the former showed markedly lower adsorption capability towards MTBE compared to the latter, implying the uptake of aqueous MTBE is not only domi- nated by the surface area and micropore volumes. In general, MTBE is considered as a hydrophilic compound with high water solu-