ABSTRACT
Due to its wide use in anticonvulsant pharmacotherapy, phenobarbital (PHEN) is an aquatic contaminant with a high prevalence in the environment. In this adsorption study, chitosan and chitosan-based magnetic adsorbents containing different amounts of incorporated magnetite (CS, CS·Fe3O4 1:1, CS·Fe3O4 1:5, and CS·Fe3O4 1:10) were used for phenobarbital removal. The magnetic adsorbents were synthesized by co-precipitation method and characterized through FTIR, XRD, MEV, and VSM analysis. In PHEN adsorption, the equilibrium and adsorption kinetic were better adjusted by the Sips and pseudo-second-order model, respectively. Among the four nanoadsorbents used, the maximum phenobarbital adsorption capacity was 94.60 mg g-1 using 25 mg of CS·Fe3O4 1:5, with a concentration of PHEN (50 mg L-1), pH 7.0 at room temperature. The parameters of pH, adsorbent dosage, ionic strength, and thermodynamic study were tested for the adsorbent with the highest performance (CS·Fe3O4 1:5). The nanoadsorbent demonstrates efficiency in the removal of the contaminant for diverse adsorption cycles. Finally, the protocol employing magnetic adsorbents dispenses the subsequent steps of filtration and centrifugation.
Subject(s)
Chitosan , Water Pollutants, Chemical , Water Purification , Chitosan/chemistry , Ferrosoferric Oxide/chemistry , Hydrogen-Ion Concentration , Thermodynamics , Adsorption , Water/chemistry , Kinetics , Water Pollutants, Chemical/chemistry , Water Purification/methods , PhenobarbitalABSTRACT
Herein, tetracycline adsorption employing magnetic chitosan (CS·Fe3O4) as the adsorbent is reported. The magnetic adsorbent was synthesized by the co-precipitation method and characterized through FTIR, XRD, SEM, and VSM analyses. The experimental data showed that the highest maximum adsorption capacity was reached at pH 7.0 (211.21 mg g-1). The efficiency of the magnetic adsorbent in tetracycline removal was dependent on the pH, initial concentration of adsorbate, and the adsorbent dosage. Additionally, the ionic strength showed a significant effect on the process. The equilibrium and kinetics studies demonstrate that Sips and Elovich models showed the best adjustment for experimental data, suggesting that the adsorption occurs in a heterogeneous surface and predominantly by chemical mechanisms. The experimental results suggest that tetracycline adsorption is mainly governed by the hydrogen bonds and cation-π interactions due to its pH dependence as well as the enhancement in the removal efficiency with the magnetite incorporation on the chitosan surface, respectively. Thermodynamic parameters indicate a spontaneous and exothermic process. Finally, magnetic chitosan proves to be efficient in TC removal even after several adsorption/desorption cycles.
