resumo
Pharmaceuticals are able to evade conventional wastewater treatments and therefore, are recurrently found in the environment with proven potential to cause harm to human and wildlife. Adsorption onto activated carbon (AC) is a promising complement. However, AC production from non-renewable resources and its difficult afteruse recuperation are prohibitive. Hence, a waste-based magnetic activated carbon (MAC) was produced from paper mill sludge, via an ex-situ synthesis, for the adsorptive removal of carbamazepine (CBZ), sulfamethoxazole (SMX) and ibuprofen (IBU) from ultrapure water and wastewater. The MAC was obtained through the promotion of electrostatic interactions between magnetic and activated carbon particles in a water suspension at controlled pH between the points of zero charge of both surfaces. The optimized condition (MACX3) presented remarkable properties regarding specific surface area (SBET=795 m2 g-1) and saturation magnetization (MS=19 emu g-1). Kinetic and equilibrium adsorption studies were performed under batch conditions. Adsorption equilibrium was reached in up to 30 min for all pharmaceuticals in both matrices, proving the low dependence on the adsorbate and the broad applicability of MACX3 in pharmaceutical adsorption. Regarding equilibrium experiments, high Langmuir maximum adsorption capacities (qm) were achieved in ultrapure water (up to 711 +/- 40 mu mol g-1). Equilibrium studies in wastewater revealed a decay in qm when compared to ultrapure water: 28% for CBZ (468 +/- 20 mu mol g-1 (111 +/- 5 mg g-1)), 78% for SMX (145 +/- 10 mu mol g-1 (37 +/- 3 mg g-1)) and 62% for IBU (273 +/- 8 mu mol g-1 (56 +/- 2 mg g-1)), attributed to the wastewater pH, which dictates the speciation of the pharma-ceuticals and controls electrostatic interactions between pharmaceuticals and MAC, and to competition effects by organic matter. It was demonstrated the promising applicability of a waste-based ex-situ MAC, rapidly retriev-able from water, as an alternative tertiary wastewater treatment for pharmaceuticals removal.
palavras-chave
EMERGING CONTAMINANTS; AQUEOUS-SOLUTION; PILOT-SCALE; REMOVAL; SURFACE; NANOPARTICLES; ADSORBENTS; IBUPROFEN; SULFAMETHOXAZOLE; MICROPOLLUTANTS
categoria
Engineering; Environmental Sciences & Ecology
autores
Pereira, D; Gil, MV; Esteves, VI; Silva, NJO; Otero, M; Calisto, V
nossos autores
Nuno João Silva
Investigador Principalagradecimentos
This work is a contribution to the project WasteMAC (POCI-01-0145-FEDER-028598) funded by FCT - Fundacao para a Ciencia e a Tecnologia, I.P., through national funds, and the co-funding by the FEDER, within the PT2020 Partnership Agreement and Compete 2020. The authors acknowledge financial support to CESAM by FCT/MCTES (UIDP/50017/2020+UIDB/50017/2020+LA/P/0094/2020), through national funds. Diogo Pereira thanks to FCT for his PhD grant (2020.05389. BD). Maria V. Gil acknowledges support from a Ramon y Cajal grant (RYC-2017-21937) of the Spanish Government and the Spanish State Research Agency, co-financed by the European Social Fund (ESF). Margarida Esteves and workers of Aveiro's WWTP ('Aguas do Centro Litoral, Portugal) are gratefully acknowledged for assistance on the effluent sampling.