Preparation and characterization of charcoal from feathers and its application in trimethoprim adsorption

Feathers were utilized to prepare charcoal which could be used for the adsorption of the antibiotic trimethoprim (TMP). The physicochemical properties of the feather-derived charcoal were determined. The feather-derived charcoal had a surface area of 805.4 m(2)/g and a well-developed microporous structure. The contents of acidic and basic functional groups on feather-derived charcoal were 1.36 and 1.76 mmol/g, respectively, and pH(pzc) = 7.52. We studied the influences of adsorbent dose, initial TMP concentration, agitation time, temperature, pH, and ionic strength on the adsorption. The desorption properties of TMP-sorbed feather-derived charcoal were also tested. The adsorption kinetics accorded with the pseudosecond-order kinetic equation, and the overall rate of adsorption was mainly controlled by intra-particle diffusion. The adsorption isotherms for the TMP-feather-derived charcoal system are explained better by the Freundlich isotherm at lower temperature (293 K) while the Langmuir isotherm gave a better fit at higher temperature (313 K). It is considered that a combination of hydrophobic interactions and ion exchange as well as electrostatic interaction was the adsorption mechanisms.