木屑生物炭的制备及其对Pb2+的吸附特性研究

以松木（SM）和楠木（NM）木屑为原料，分别在300、450、600℃下制备了6种木屑生物炭，通过扫描电镜、孔径与比表面积分析仪、傅里叶红外光谱仪和热重分析仪对生物炭的理化性质进行了表征，并探讨了金属离子（Na⁺、K⁺、Ca²⁺）和pH值对生物炭吸附Pb²⁺的影响，同时研究了其吸附动力学。研究结果表明：在相同制备条件下，随着热解温度升高，生物炭的比表面积和孔容积增大，其最可几孔径呈下降趋势，楠木生物炭的比表面积（23.2~311.4 m²/g）均大于松木生物炭（17.6~210.6 m²/g）；FT-IR分析表明，热解温度的升高使生物炭芳香化程度增强，有助于生物炭与Pb²⁺形成稳定的结构。楠木生物炭对Pb²⁺吸附量（46.92~77.12 mg/g）高于松木生物炭（34.90~62.79 mg/g）；溶液中的Na⁺和K⁺不利于生物炭对Pb²⁺的吸附，Ca²⁺有利于Pb²⁺的去除。生物炭对Pb²⁺的吸附均符合准二级动力学方程，颗粒内扩散模型分析表明吸附受多种因素共同影响。

Preparation of Biochar from Sawdust and It's Adsorption Property on Pb2+

Using pine(SM) and nanmu(NM) wood sawdust as raw materials, six kinds of wood sawdust biochar were prepared at 300, 450, and 600 ℃, respectively. Scanning electron microscope, aperture and specific surface area analyzer, Fourier infrared spectrometer and thermogravimetric analyzer were used to characterize the physicochemical properties, and the effects of metal ions (Na⁺, K⁺, Ca²⁺) and pH value on Pb²⁺ adsorption by biochar were investigated, and the adsorption kinetics were also studied. The results showed that under the same preparation conditions, with the increase of pyrolysis temperature, the specific surface area and pore volume of biochar increased, and its most probable diameter showed a downward trend. The specific surface areas of nanmu sawdust biochar (23.2-311.4 m²/g) were larger than those of pine biochar (17.6-210.6 m²/g); FT-IR analysis showed that the increase in pyrolysis temperature increased the degree of aromatization of the biochar and helped the biochar and Pb²⁺ form a stable structure. The Pb²⁺ adsorption capacities of nanmu sawdust biochar (46.92-77.12 mg/g) were higher than those of pine wood sawdust biochar (34.89-62.79 mg/g); Na⁺ and K⁺ in solution were not conducive to the adsorption of biochar to Pb²⁺, and Ca²⁺ was beneficial to remove. The adsorption of biochar to Pb²⁺ conformed to the quasi-second-order kinetic equation. The analysis of the intra-particle diffusion model showed that the adsorption was affected by many factors.