2.4. Adsorption isotherms
Adsorption isotherms of MTBE onto commercial chloromethy- lated polymer, nonpolar porous polymer, and postcrosslinked polymer were determined by batch tests. Carefully weighed amounts of adsorbents were introduced into 50-ml glass tubes containing 50 ml of MTBE aqueous solution with known initial con- centrations. The tubes were Teflon sealed and placed in a constant temperature incubating shaker, in which adsorption was allowed to last 48 h at 25 ◦ C to reach the adsorption equilibrium. Samples were then taken from the solution for MTBE concentration measurement using an Agilent 6890 gas chromatograph with purge & trap Tek- mar Dohrmann 3100 Sample Concentrator. The adsorption amount of MTBE in the sample was calculated according to the following equation:
qe=(C0−Ce)V (1) M
where qe is the equilibrium adsorption amount (mg g−1 ), C0 is the initial concentration of MTBE solution (mgl−1), Ce is the equilib- rium concentration of MTBE (mg l−1 ), V is the volume of MTBE solution (l), and M is the mass of polymeric adsorbent (g).