花生壳生物炭的改性及其吸附Pb2+性能研究

以花生壳为原料热解制备生物炭，并分别采用NaOH和KMnO₄进行改性，经表征发现改性后生物炭微观结构较为疏松、孔径变小、稳定性增强，NaOH改性花生壳生物炭（AB）和KMnO₄改性花生壳活性炭（MnB）的比表面积分别增至花生壳生物炭（B）的3.178倍和5.065倍，以KMnO₄作为改性剂时，锰氧化物成功地固定在生物炭上，B、AB和MnB的零电荷点（pH_PZC）分别为2.193、2.888和2.466。探究改性前后生物炭对Pb²⁺的吸附性能发现：B、AB和MnB吸附Pb²⁺的适宜pH值分别为4.5~6.5、5.5~6.5和5.0~6.5，达到相同Pb²⁺去除率时，生物炭用量MnB 2+的吸附平衡时间较B吸附Pb²⁺的吸附平衡时间（1 080 min）分别缩短了180和480 min。通过吸附动力学模型和等温线模型分析可知，3种生物炭吸附Pb²⁺的过程均受化学吸附控制，吸附速率MnB>AB>B，AB和MnB的最大理论吸附量分别是53.19和80.65 mg/g，分别提高至B的1.38倍和2.10倍。

Modification of Peanut Shell Biochar and Its Adsorption Properties of Pb2+

In this study, peanut shell was used as raw material to produce biochar by pyrolysis, and the product of biochar was modified by NaOH and KMnO₄, respectively. Characterization results showed that the microstructure of the modified biochar was relatively dispersed, the pore size was decreased, and the stability was enhanced. The specific surface area of NaOH modified peanut shell biochar(AB) and KMnO₄ modified peanut shell biochar(MnB) increased up to 3.178 times and 5.065 times than that of peanut shell biochar(B), respectively. When KMnO₄ was used as modifying agent, manganese oxide was successfully fixed on the biochar. The zero point charge (pH_PZC) of B, AB, and MnB were 2.193, 2.888, and 2.466, respectively. The adsorption performance of Pb²⁺ using biochar before and after modification was investigated. It was found that the optimum pH values for the adsorption of Pb²⁺ using B, AB, and MnB were 4.5-6.5, 5.5-6.5 and 5.0-6.5, respectively. When the removal rate of Pb²⁺ was the same, the biochar dosage was MnB < AB < B, and the equilibrium adsorption time of Pb²⁺ using AB and MnB was shortened by 180 and 480 min, respectively. The adsorption kinetics model and isotherm model showed that the Pb²⁺ adsorption process was controlled by chemisorption in three biochars, and the order of adsorption rates was MnB>AB>B. The maximum theoretical adsorption amounts of AB and MnB were 53.19 and 80.65 mg/g, which were 1.38 and 2.10 times than that of B, respectively.