Potential of chitosan and activated carbon biocomposites for removing enrofloxacin and oxytetracycline from water

Enrofloxacin (ENRO) and oxytetracycline (OTC) are two antibiotics, which are difficult to remove by conventional water treatment methods. The characteristics of the biocomposites suggest that they could represent an alternative for the removal of this type of substances through adsorption processes. The current study aimed to determine and compare the potential of biocomposites formed with chitosan and different concentrations of activated carbon (AC) with a particle size of 500 nm, prepared from agave bagasse, to remove enrofloxacin and oxytetracycline solved in water. The effectiveness of the addition of different concentrations of AC (0, 0.5, 2 and 5% w/v) to chitosan was evaluated by morphological analysis using scanning electron microscopy (SEM). The detection of the characteristic functional groups carried out by Fourier transform infrared spectroscopy (FTIR) indicated that the nanoparticles of AC were attached in the chitosan biocomposite, and stable chemical crosslinking was formed during the polymerization process. The removal test of ENRO (10 mg/mL) and OTC (10 mg/mL) in a water was performed by a gradient method of high-performance liquid chromatography (HPLC). The results showed that the addition of AC to chitosan formed a biocomposite with maximum capacity to remove 59.3% of OTC (contact time 2 h at 100 rpm, 4 g biocomposite/L solution, pH 6-7, 30 ºC), and a maximum removal of 50.3% of ENRO (contact time 2 h at 100 rpm, 4 g biocomposite/L solution, pH 6, 30 ºC). Biocomposites formed by chitosan and agave activated carbon can support the development of tools for the removal of recalcitrant antibiotics from water bodies.