Study on the Adsorption Performance of Tannery Sludge Biochar Towards Methylene Blue from Wastewater

Tannery sludge was used as raw material to prepare the biochar (TSBC) by traditional pyrolysis method under a nitrogen atmosphere, and the adsorption performance and mechanism of TSBC were studied using methylene blue (MB) as model pollutant. The results indicated that the properties reached the maximum at 500 ℃. The specific surface area and average pore diameter of TSBC₅₀₀ were 40.98 m²/g and 9.21 nm, respectively, and a large number of oxygen-containing functional groups such as -OH and -COOH were formed on the surface. Compared with the TSBC obtained under other pyrolysis temperatures, TSBC₅₀₀ showed the superior removal efficiency of MB (92.3%), and the maximum adsorption capacity reached up to 76.34 mg/g. Besides, the adsorption process of MB was in accordance with a pseudo-second-order kinetics and the Langmuir isotherm well. Combined with FTIR analysis, the adsorption mechanism of TSBC₅₀₀ on MB was mainly dependent on the electrostatic attraction, hydrogen-bond interaction, ion exchange, π-π EDA.