In the recent past few years, antibiotics have raised a significant concern from the research community, due mainly to the antibiotic resistance generated by metabolites and the continuous release of these drugs to the environment. Adsorption, since it is a non-destructive tertiary technology, has been revealed as one of the most advantageous technique in wastewater treatment processes. Commercial activated carbons usually show high affinity to hundreds of organic and inorganic compounds, since the use of commercial materials is associated to high operation and regeneration costs. So, the preparation of activated carbons from crude glycerol, an abundant feedstock of the biodiesel production, consists of an interesting research focus.
The aim of this study is to explore several glycerol-based carbon materials synthesized by partial carbonization in concentrated sulfuric acid solution and further thermal activation for the removal of the antibiotics flumequine (FLQ) and tetracycline (TCN) from water.
This study is focused on the synthesis and application of glycerol-based carbon materials (GBCM200,
GBCM300 and GBCM350) as adsorbents for the removal of the antibiotic compounds flumequine and tetracycline
from aqueous solution. The synthesis enrolled the partial carbonization of a glycerol-sulfuric acid
mixture, followed by thermal treatments under inert conditions and further thermal activation under
oxidative atmosphere. The textural properties were investigated through N2 adsorption–desorption
isotherms, and the presence of oxygenated groups was discussed based on zeta potential and Fourier
transform infrared (FTIR) data. The kinetic data revealed that the equilibrium time for flumequine
adsorption was achieved within 96 h, while for tetracycline, it was reached after 120 h. Several kinetic
models, i.e., pseudo-first order, pseudo-second order, fractional power, Elovich and Weber–Morris
models, were applied, finding that the pseudo-second order model was the most suitable for the fitting
of the experimental kinetic data. The estimated surface diffusion coefficient values, Ds, of 3.88 and
5.06 10 14 m2 s 1, suggests that the pore diffusion is the rate limiting step of the adsorption process.
Finally, as it is based on SSE values, Sips model well-fitted the experimental FLQ and TCN adsorption isotherm
data, followed by Freundlich equation. The maximum adsorption capacities for flumequine and
tetracycline was of 41.5 and 58.2 mg g 1 by GBCM350 activated carbon.
