Rhodamine B Adsorption Efficiency of Biochar Produced Through Co‐Pyrolysis of Municipal Sewage Sludge and Food Waste Mixture Under High‐Temperature Condition

ABSTRACT With the large‐scale construction of wastewater treatment facilities, the production of municipal sewage sludge continues to rise. This sludge contains substantial amounts of toxic and hazardous substances, and improper disposal may lead to secondary environmental pollution. In this study, biochar was prepared by co‐pyrolysis of municipal sewage sludge and food waste as raw materials mixed in various mass ratios. N 2 adsorption and desorption experiments were conducted on the product to determine and analyze its specific surface area and pore structure. Results revealed that the optimal adsorption performance was achieved with a 4:1 mass ratio of sewage sludge to food waste at 800°C (W4 biochar). Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), and energy‐dispersive spectroscopy (EDS) were employed to characterize the prepared biochar. W4 biochar exhibits the optimal specific surface area and pore structure, with its inorganic framework demonstrating excellent chemical inertness. Operational parameters influencing the adsorption effect of W4 biochar on Rhodamine B (RhB), including the dosage, contact time, and pH, were investigated. Adsorption kinetics and adsorption isotherms were studied by analyzing the adsorption effect. Adsorption kinetics of the RhB by biochar was more in line with the pseudo–second order adsorption kinetic equation, and the adsorption process more closely fit the Freundlich adsorption isotherm model. This study demonstrates that the prepared biochar exhibits a high RhB adsorption capacity in the wastewater, and reveals its potential as an effective adsorbent for removing the RhB from printing and dyeing wastewater.