Microporous organic polymers for efficient removal of sulfamethoxazole from aqueous solutions

Widespread use of pharmaceuticals, especially antibiotics is causing serious contamination of both surface and underground water. In this study, four different microporous organic polymers (MOP): microporous triazine polymer (MCTP), carbonyl-incorporated aromatic polymer (CBAP), CBAP-functionalized with ethylenediamine (CBAP-EDA), and CBAP-functionalized with sulfonic acid (CBAP-SO3H) were synthesized and tested for adsorptive removal of the common antibiotic sulfamethoxazole (SMX) from aqueous solutions. MCTP with the largest BET surface area (1406 m(2)/g) attained equilibrium in 1 h and showed the highest SMX adsorption capacities (ca. 483 mg/g), significantly better than that of a commercial activated carbon (AC, 259 mg/g) with the sequence of AC < CBAP-EDA < CBAP < CBAP-SO3H < MCTP. The pseudo-second-order model validated the adsorption kinetics while the Langmuir isotherm model gave the best fit for the experimental isotherm data involving MCTP. The effect of the solution pH on adsorption revealed that MCTP performs better in acidic than in basic media. pi-pi stacking interaction between SMX and MCTP was used to explain the adsorption behavior. Easy recyclability and reusability of MCTP were also demonstrated, and higher than 95% adsorption capacity after the 4th runs was possible after ethanol or acetone washing applied for adsorbent regeneration.