Adsorption of methylene blue by biochar prepared using straw mixed with agricultural film

In order to explore the effect of agricultural film doping on the structure and adsorption properties of straw biochar materials, the graphitized biochar of SPS600-B was prepared using waste corn straw mixed with polyethylene agricultural film as raw materials and anhydrous potassium carbonate as modifier. The material was characterized by SEM, TEM, BET, XRD and elemental analysis. The adsorption performance and mechanism for methylene blue(MB) by SPS600-B were investigated. The results showed that SPS600-B was highly graphitized with many non-penetrating pore and carbon microsphere structures on its surface, and the specific surface area was 821.96 m2/g. At 25 ℃ and pH=7, the removal rate of 100 mg/L MB by 0.2 g/L SPS600-B reached 93.2%, and the adsorption capacity was 466.2 mg/g. After 5 cycles of adsorption-desorption recycling, the removal rate of MB could still reach 79.4%. The adsorption mechanism revealed that the adsorption process conformed to the quasi-second-order kinetic model and Langmuir model, which was dominated by chemisorption. The adsorption process was affected by pore adsorption, electrostatic attraction, π-π electron interaction and hydrogen bonding. The adsorption behaviour was a spontaneous adsorption reaction.