Chemical analysis

The dosage of biochar and Fe-BC were both 2.0 g/L, the concentration of mass Cu²⁺ was set to 20 mg/L, using a certain concentration of HNO₃ and NaOH to adjust the pH of the solution to about 5.5, the oscillation speed was 150 r/min, and the operating temperature was 25 °C. The samples were taken at 0, 5, 10, 20, 30, 60, 90, 120, 180, 240, 300, 360 and 480 min successively. After the adsorption experiment was completed, the conical bottle was removed, left for 30 min, and then filtered with a 0.45 μm filter membrane. The filtrate was put into the sample bottle to determine the concentration of heavy metal ions in the solution. The adsorption kinetics were fitted using the experimental results of reaction time.

The dosage of biochar and Fe-BC were both 2.0 g/L, the level of heavy metal ions was set as 10, 20, 50, 100, 200, 500, 800 and 1000 mg/L, and use a certain concentration of HNO₃ and NaOH to adjust the pH of the solution to about 5.5. The oscillation speed is 150 r/min, the operating temperature is 298 K, and the oscillation is 300 min. After the adsorption experiment was completed, the conical bottle was removed, left for 30 min, and then filtered with a 0.45 μm filter membrane. The filtrate was put into the sample bottle to determine the heavy metal ion concentration present in the solution.