RESUMO
Rapid synthesis of carbon-based magnetic materials derived from cobalt and iron metal-organic frameworks (MOFs), ZIF-67, and MIL-100(Fe), by microwave-assisted method, followed by carbonization under a N2 atmosphere is described in this study. The carbon-derived MOFs (CDMs) were evaluated for the removal of the emerging pollutants sulfadiazine (SDZ) and flumequine (FLU) used as veterinary drugs. The study aimed to link the adsorption behavior with their surface properties and elemental composition. C-ZIF-67 and C-MIL-100(Fe) showed hierarchical porous structures with specific surface areas of 295.6 and 163.4 m2 g-1, respectively. The Raman spectra of the CDMs show the characteristic D and G bands associated with defect-rich carbon and sp2 graphitic carbon, respectively. The CDMs exhibit cobalt species (Co3O4, CoO, and Co) in C-ZIF-67 and iron species (Fe2O3, Fe3O4, and Fe) in C-MIL-100 (Fe) which are related to the magnetic behavior of CDMs. C-ZIF-67 and C-MIL-100 (Fe) had saturation magnetization values of 22.9 and 53.7 emu g-1, respectively, allowing easy solid-liquid separation using a magnet. SDZ and FLU removal rates on CDMs follow pseudo-second-order kinetics, and adsorption isotherms fit the Langmuir model based on regression coefficient values. Adsorption thermodynamics calculations showed that the adsorption of SDZ and FLU by CDMs was a thermodynamically favorable process. Therefore, these properties of C-ZIF-67 and C-MIL-100 (Fe) and their regeneration ability facilitate their use as adsorbents for emerging pollutants.
Assuntos
Estruturas Metalorgânicas , Drogas Veterinárias , Poluentes Químicos da Água , Estruturas Metalorgânicas/química , Ferro/química , Poluentes Químicos da Água/análise , Carbono , Adsorção , Água/químicaRESUMO
In this study, the residual pods of the forest species Erythrina speciosa were carbonized with ZnCl2 to obtain porous activated carbon and investigated for the adsorptive removal of the drug paracetamol (PCM) from water. The PCM adsorption onto activated carbon is favored at acidic solution pH. The isothermal studies confirmed that increasing the temperature from 298 to 328 K decreased the adsorption capacity from 65 mg g-1 to 50.4 mg g-1 (C0 = 175 mg L-1). The Freundlich model showed a better fit of the equilibrium isotherms. Thermodynamic studies confirmed the exothermic nature (ΔH0 = -39.1066 kJ mol-1). Kinetic data indicates that the external mass transfer occurs in the first minutes followed by the surface diffusion, considering that the linear driving force model described the experimental data. The application of the material in the treatment of a simulated effluent with natural conditions was promising, presenting a removal of 76.45%. Therefore, it can be concluded that the application of residual pods of the forest species Erythrina speciosa carbonized with ZnCl2 is highly efficient in the removal of the drug paracetamol and also in mixtures containing other pharmaceutical substances.
Assuntos
COVID-19 , Erythrina , Poluentes Químicos da Água , Carvão Vegetal/química , Poluentes Químicos da Água/química , Adsorção , Acetaminofen , Cinética , Analgésicos , Concentração de Íons de HidrogênioRESUMO
Schizolobium parahyba species can be found in all of South America, producing several residues that can be a major opportunity to develop activated carbon. This work presents the investigation regarding the development of a high specific surface activated carbon (981.55 m2 g-1) and its application in the adsorption of ketoprofen from the aqueous media. The ketoprofen molecules were better adhered to the adsorbent surface under acidic conditions (pH = 2), being the ideal adsorbent dosage determined as 0.7 g L-1, resulting in satisfactory values. It was found that the system reached equilibrium in 200 to 250 min depending on the initial concentration studied, achieving an adsorption capacity of 229 mg g-1. The general order was the most suitable model for describing the experimental data, with an R2 ≥ 0.9985 and MSR ≤ 63.40 (mg g-1)2. The equilibrium adsorption found that the temperature increases the adsorption capacity, achieving 447.35 mg g-1 at 328 K. Besides that, the Tóth model was the most suitable for describing the isotherms R2 ≥ 0.9990 and MSR ≤ 25.67 (mg g-1)2, indicating a heterogeneous adsorbent. The thermodynamic values found that the adsorption of ketoprofen is spontaneous (average ΔG0 of - 32.79 kJ mol-1) and endothermic (ΔH0 10.44 kJ mol-1). The treatment of simulated effluent with the developed adsorbent was efficient, removing 90% of ketoprofen, ibuprofen, and salts. It was found that the adsorbent is reaming its adsorption capacity up to the 5th cycle, progressively decreasing the adsorption capacity until the adsorption does not occur past the 12th cycle. Overall, the results demonstrated that the activated carbon from residual biomass of the Schizolobium parahyba species could be an excellent alternative in obtaining an effective adsorbent to treat wastewater-containing drugs.