氧化老化玉米秸秆生物炭吸附镉机理研究

为研究玉米秸秆生物炭在经过模拟自然界老化后对Cd²⁺的吸附响应，本文利用H₂O₂对玉米秸秆生物炭进行氧化老化1、2、3次，利用元素分析仪、扫描电镜、红外光谱及碳谱等分析方法，分析老化前后生物炭对Cd²⁺的吸附及响应机理。结果表明：玉米秸秆生物炭氧化老化过程中形成硅酸盐沉淀；经过H₂O₂老化后H/C、O/C和（O+N）/C的原子比逐渐升高，使得生物炭含氧官能团上升、芳香性减弱、极性增强；老化1次（OYM1）、2次（OYM2）、3次（OYM3）后玉米秸秆生物炭碱性元素逐步被释放，碱性元素较未氧化玉米秸秆生物炭（YM）分别降低了48.23%、95.04%、95.74%；不同处理生物炭对Cd²⁺的最大吸附量表现为： YM（12.42 mg·g^-1） >OYM1（5.98 mg·g^-1） >OYM3（3.88 mg·g^-1） >OYM2（3.61 mg·g^-1），说明老化作用抑制了其对Cd²⁺的吸附。在玉米秸秆生物炭长期利用过程中，生物炭的老化促进无机组分发挥作用，吸附性能减弱，在进行土壤及水污染修复时应合理使用。

Mechanism of cadmium adsorption by oxidative aging corn straw biochar

To study the adsorption response of corn straw biochar to Cd²⁺ after simulated natural aging, corn straw biochar was oxidized and aged for 1, 2, and 3 times using H₂O₂. The adsorption and response mechanism of Cd²⁺ by biochar before and after aging were analyzed using elemental analyzer, scanning electron microscope, infrared spectrum, and carbon spectrum. The results showed that silicate precipitation was formed during the oxidative aging of corn straw biochar. After H₂O₂ aging, the atomic ratios of H/C, O/C, and(O+N)/C gradually increased, resulting in the increase of oxygen-containing functional groups, weakening of aromaticity and enhancement of polarity of biochar. After aging for 1, 2, and 3 times, the alkaline elements of corn straw biochar OYM1, OYM2, and OYM3 were released, and the alkaline elements were reduced by 48.23%, 95.04%, and 95.74%, respectively compared with the unaged corn straw biochar (YM). The maximum adsorption capacity of aged corn straw biochar for Cd²⁺ was in the order as follows:YM(12.42 mg·g^-1) >OYM1(5.98 mg·g^-1) >OYM3(3.88 mg·g^-1) >OYM2(3.61 mg·g^-1), indicating that aging inhibits its adsorption of Cd²⁺. Long-term usage of corn straw biochar may probably promote the role of inorganic components and weaken its adsorption performance; therefore, it should be used reasonably in the remediation of soil and water pollution.