Adsorption Characteristics of Water Ciprofloxacin on Co‐Pyrolysis Biochar Derived from Rubber and Ginkgo Biloba Leaves

Abstract

Taking rubber and ginkgo biloba leaves as raw materials (the mass ratio is 5 : 2), this study prepared biochar by co‐pyrolysis at 700–900 °C and explored its adsorption performance on the emerging water pollutant ciprofloxacin. The pyrolysis behaviors of rubber, ginkgo biloba leaves, and their mixture were investigated using a thermogravimetric analyzer. The microstructure and physicochemical properties of the co‐pyrolysis biochar prepared in this study were probed through scanning electron microscopy (SEM), Brunauer‐Emmett‐Teller (BET) and element analysis. Meanwhile, the internal mechanism of prepared co‐pyrolysis biochar adsorbing ciprofloxacin was investigated using adsorption kinetics models and isotherm adsorption models. The results show that there is a synergistic effect between rubber and ginkgo biloba leaves during the co‐pyrolysis process. Due to the addition of ginkgo biloba leaves, the maximum mass loss rate of rubber reduces from −5.80 %/min to −4.98 %/min, the corresponding pyrolysis temperature decreases from 335.11 °C to 319.57 °C, and the calculated thermogravimetric analysis (TG) and differential thermogram (DTG) curves after mixing the two raw materials deviate from the experimental curves. As the pyrolysis temperature increases from 700 °C to 900 °C, the yields of biochars decrease from 28.62 % to 19.21 %, while the specific surface area significantly increases (337.5042 m2/g). The processes of co‐pyrolysis biochars prepared at different temperatures absorbing ciprofloxacin conform to the pseudo‐second‐order model (R2=0.9847, 0.9404 and 0.9772, respectively). The Langmuir‐Freundlich model describes the isotherm adsorption behaviors of co‐pyrolysis biochars prepared at different temperatures on ciprofloxacin excellently (R2=0.9976, 0.9995 and 0.9993). The co‐pyrolysis biochar prepared at 900 °C has the highest adsorption capacity for ciprofloxacin, 306.6 mg/g. This study provides an essential reference for the application of co‐pyrolysis biochar of low‐cost and environment‐friendly in the removal of water pollutants.