Paper pulp-based adsorbents for the removal of pharmaceuticals from wastewater: A novel approach towards diversification

Highlights: • Raw and bleached paper pulps were used to generate carbon adsorbents. • Carbons were characterized and used to remove 2 pharmaceuticals from water. • Activation with K₂CO₃ or H₃PO₄ provided highly porous materials (S_BET up to 965 m² g⁻¹). • H₃PO₄-activated carbons were efficient adsorbents both in ultra-pure and wastewater. In this work, two pulps, bleached (BP) and raw pulp (RP), derived from the paper production process, were used as precursors of non-activated and activated carbons (ACs). In the case of non-ACs, the production involved either pyrolysis or pyrolysis followed by acid washing. For ACs production, the pulps were impregnated with K₂CO₃ or H₃PO₄, and then pyrolysed and acid washed. After production, the materials were physically and chemically characterized. Then, batch adsorption tests on the removal of two pharmaceuticals (the anti-epileptic carbamazepine (CBZ) and the antibiotic sulfamethoxazole (SMX)) from ultra-pure water and from Waste Water Treatment Plant (WWTP) effluents were performed. In ultra-pure water, non-ACs were not able to adsorb CBZ or SMX while ACs showed good adsorption capacities. In WWTP effluents, although ACs satisfactorily adsorbed CBZ and SMX, they showed lower adsorption capacities for the latter. Tests with WWTP effluents revealed that the best adsorption capacities were achieved by carbons produced from BP and activated with H₃PO₄: 92 ± 19 mg g⁻¹ for CBZ and 13.0 ± 0.6 mg g⁻¹ for SMX. These results indicate the potential of paper pulps as precursors for ACs that can be applied in wastewater treatment.