Characterization of Activated Carbon Fiber by Microwave Heating and the Adsorption of Tetracycline Antibiotics

Abstract

In this research, activated carbon fiber heated by microwave (WACF) under nitrogen (N₂) atmosphere adsorption of tetracycline antibiotics (TCs) was analyzed. WACF was obtained under the microwave radiation temperature of 600°C and the radiation time of 15 min. The properties of WACF were characterized by a scanning electron microscope (SEM), N₂ adsorption/desorption isotherms, and X-ray diffraction (XRD) compared with activated carbon fibers (ACF) without any treatment. WACF had lower surface area (1008 m²/g) but higher external surface area (429 m²/g) than ACF (surface area: 1153 m²/g; external surface area: 308 m²/g). Meanwhile, the adsorption efficiencies of TCs (including tetracycline hydrochloride (TC) and oxytetracycline hydrochloride (OTC)) on WACF were both increased by about 4 times. These results indicated that mesoporosity amplification of WACF played a crucial role in the adsorption capacity of the two TCs. The kinetics and equilibrium data were agreed well with the pseudo-second-order kinetics model (R² > 0.99) and Langmuir isotherm model (R² > 0.98), respectively. It suggested that the adsorption process was dominated by chemisorption. Batch experiments showed the maximum adsorption capacities for both adsorbates were 339 and 331 mg/g respectively at pH 2.

Keywords:

• activated carbon fiber
• adsorption
• microwave
• tetracycline antibiotics