玉米芯基和羊粪基生物炭对亚甲基蓝的吸附特性

Adsorption Properties of Methylene Blue by Biochars Derived from Corn Cob and Sheep Manure

在600℃热解温度下制备玉米芯基生物炭(CCB_(600))和羊粪基生物炭(SMB_(600)),对比分析了他们的理化性质,并通过序批实验探讨了其对亚甲基蓝(MB)的吸附特性。结果表明,SMB_(600)的比表面积、总孔容、平均孔径分别是CCB_(600)的7.71、4.62、2.3倍,且具有更高的芳香性和极性。在初始MB的质量浓度为50 mg/L、p H为11,CCB_(600)、SMB_(600)投加量分别为0.5、0.3 g/L时,吸附在210 min左右达到平衡,对MB的去除率分别为93.57%、95.24%。采用准2级动力学模型和Freundlich模型能更准确地描述MB在2种生物炭上的吸附行为,吸附速率由液膜扩散、表面吸附和颗粒内扩散等共同控制。2种生物炭对MB的吸附均属于自发、吸热、熵增的过程,主要通过物理作用进行吸附。氢键和π-π键作用在MB的吸附过程中起到重要作用。SMB_(600)的吸附性能明显优于CCB_(600),更适合作为水中MB的吸附剂。

Corn cob biochar （CCB600） and sheep manure biochar （SMB600） were prepared at 600℃ pyrolysis temperature, and the physicochemical properties of CCB600 and SMB600 were compared and analyzed, and their adsorption properties of methylene blue （MB） were investigated by batch experiments. The results showed that, The specific surface area, total pore volume and average pore diameter of SMB600 were 7.71, 4.62 and 2.3 times of CCB600 respectively. Besides, SMB600 had higher aromaticity and polarity than CCB600. When the initial mass concentration of MB was 50 mg/L, pH was 11, and the dosage of CCB600 and SMB600 was 0.5 and 0.3 g/L respectively, the adsorption reached a balance at about 210 min, and MB removal rate was 93.57% and 95.24% respectively. The pseudo-second-order kinetic model and Freundlich isotherm model could describe the adsorption behavior of MB on biochars more accurately. The adsorption rate was controlled by liquid film diffusion, surface adsorption and intraparticle diffusion. The adsorption of MB on these two biochars was a spontaneous and endothermic process with entropy production, and the adsorption mainly depended on physical interaction. Hydrogen bonds and π- π bonds played an important role in MB adsorption. The adsorption capacity of SMB600 was better than that of CCB600, it was more suitable to be used as an ideal adsorbent for MB in aqueous solution.