Effect of the surface functionalization of a waste-derived activated carbon on pharmaceuticals' adsorption from water

Abstract

The functionalization of a paper mill sludge-based activated carbon (AC) was addressed in this work for the first time. Four different procedures have been accomplished in order to introduce amine functional groups (AC-NH2 and AC-APTES), thiol functional groups (AC-MPTMS), and a covalent organic polymer (AC-COP) onto the AC surface. The materials were characterized showing that the functionalization was succeeded, with a reduction of the specific surface area (SBET), except for AC-MPTMS. The produced ACs were tested for the removal of six pharmaceuticals - carbamazepine (CBZ), lorazepam (LOR), sulfamethoxazole (SMX), piroxicam (PIR), paroxetine (PAR), and venlafaxine (VEN) - from different matrices (ultrapure water, ultrapure water with pH adjusted to 7.6, and effluent from a municipal wastewater treatment plant (WWTP)). The results indicated textural parameters, SBET, micropore area and micropore volume, as the main factors influencing the adsorption, except for AC-NH2 which showed a great specificity for PAR and VEN. Also, AC-MPTMS presented a high removal percentage of the antibiotic SMX in wastewater. Overall, AC-MPTMS and AC-APTES provided, respectively, the best and the poorest adsorptive performance. Although the functionalization did not result in the enhancement of pharmaceuticals’ adsorption as compared with the parent AC, the selectivity for some pharmaceuticals was highly improved.