Mixed-Matrix Membrane Adsorbers for the Simultaneous Removal of Different Pharmaceutical Micropollutants from Water

The lack of a complete removal of pharmaceutical contaminants from water by conventional wastewater treatment plants requires additional separation processes. In this work, the ability of mixed-matrix membrane (MMM) adsorbers for the simultaneous removal of pharmaceuticals was investigated using three types of strong anion-exchange particles. Diclofenac (DCF), sulfamethoxazole (SMX), carbamazepine (CBZ), and metoprolol (MTP) were used as model substances because they have medical relevance and different chemical characteristics. Spherical nonporous and porous polymer adsorbent particles were synthesized by emulsion and miniemulsion polymerization, respectively, followed by polymer-analogous functionalization. In addition, a commercially available, ground polymer gel ion-exchange adsorbent was used. Adsorption properties of the anion-exchange particles were determined for individual substances and multicomponent mixtures and analyzed via Freundlich and Langmuir isotherm models. All particles showed an excellent adsorption of DCF, revealing Freundlich constants (KF) up to 278 (mg g-1/mg L-1)n. Furthermore, the use of either nonporous or porous adsorber particles enabled the removal of DCF with high adsorption capacities simultaneously with SMX or CBZ, respectively. MMM adsorbers were prepared by incorporation of the adsorber particles into porous poly(vinylidene fluoride) hollow fiber membranes via wet spinning. Dynamic adsorption measurements using the MMM adsorbers for pharmaceuticals at 5 mg L-1 in tap water revealed adsorption capacities up to 13.7 g m-2 (relative to the membrane filter area) for DCF while SMX was adsorbed simultaneously with a capacity of 0.60 g m-2.