Removal of enrofloxacin residues from aquaculture tailwater by graphitized carbon black

This study explored and evaluated the adsorption capacity of graphitized carbon black (GCB) to remove enrofloxacin (ENR) in an aquaculture environment. GCB was characterized by scanning electron microscope, Fourier transform infrared spectrometer, Raman spectrum and Zeta potential. Additionally, the effects of pH value, adsorption temperature (T), initial concentration of ENR (C₀) and adsorption time (t) on the adsorption of ENR by GCB were determined. Meanwhile, the adsorption thermodynamics and adsorption kinetics of ENR by GCB were explored to reveal its adsorption mechanisms. The results showed that GCB had good adsorption performance to ENR, which can be described by the pseudo-second-order kinetic model and the Freundlich adsorption isotherm model. Under the conditions of <inline-formula><alternatives><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M4"><mml:mi mathvariant="normal">p</mml:mi><mml:mi mathvariant="normal">H</mml:mi></mml:math><inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/CA0670B4-087A-463a-88EB-FC504D1834F3-M004c.jpg"/></alternatives></inline-formula>=7, <inline-formula><alternatives><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M5"><mml:msub><mml:mrow><mml:mi>C</mml:mi></mml:mrow><mml:mrow><mml:mn mathvariant="normal">0</mml:mn></mml:mrow></mml:msub></mml:math><inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/CA0670B4-087A-463a-88EB-FC504D1834F3-M005c.jpg"/></alternatives></inline-formula>=200 mg/L and <inline-formula><alternatives><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M6"><mml:mi>T</mml:mi></mml:math><inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/CA0670B4-087A-463a-88EB-FC504D1834F3-M006c.jpg"/></alternatives></inline-formula>=35 ℃, GCB had the strongest adsorption capacity for ENR in solution, and the maximum adsorption quantity could reach 74.43 mg/g. Furthermore, it was found that GCB demonstrated good adsorption quantity on ENR residues in actual spiked cultural freshwater and spiked cultural seawater, and the unit adsorption quantities were (32.47±0.99) mg/g and (31.84±1.46) mg/g, respectively. In conclusion, GCB has the potential to remove ENR from real aquaculture tailwater.