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为了研究老化作用对生物炭性质及其对重金属Cd吸附的影响,将浮萍生物炭(LM)分别进行了高温老化(high temperature aging),冻融循环老化(freeze-thaw cyclesaging)和自然老化(spontaneous aging),通过SEM-EDS、FTIR和吸附实验探究可能存在的机理。结果显示,冻融循环老化和高温老化会使生物炭表面O/C比分别增加至56.98%和90.14%,自然老化比较缓慢,对生物炭O/C比影响不大。高温老化使生物炭表面羟基转化为羧基,为羧基化过程;冻融循环老化会使生物炭表面羟基增加,其他官能团基本不变;自然老化条件下,生物炭表面官能团无明显变化。老化作用增强了生物炭对Cd的吸附,冻融循环、高温、自然老化使最大平衡吸附量分别增加了32.67%,83.17%,15.97%。研究表明生物炭的老化会使生物炭本身性质发生变化,但这一变化有利于生物炭对重金属的吸附,生物炭在环境中具有较好的稳定性。
In order to study the effect of aging on biochar properties and its effect on heavy metal Cd adsorption, duckweed biochar (LM) was subjected to high temperature aging, freeze-thaw cyclesaging and natural aging spontaneous aging), probing the possible mechanism through SEM-EDS, FTIR and adsorption experiments. The results showed that the freeze-thaw cycles and high temperature aging could increase the surface O / C ratio of biochar to 56.98% and 90.14%, respectively. Natural aging was relatively slow and had little effect on O / C ratio of biochar. The high temperature aging changed the hydroxyl groups on the surface of biochar into carboxyl groups, which was the carboxylation process. The freeze-thaw cycles would increase the hydroxyl groups on the surface of biochar while the other functional groups would not change. Under natural aging conditions, the surface functional groups of biochar did not change obviously. Aging increased biosorption of Cd, freeze-thaw cycles, high temperature, natural aging so that the maximum equilibrium adsorption capacity increased by 32.67%, 83.17%, 15.97%. Research shows that the aging of biochar will change the nature of biochar itself, but this change is conducive to biochar adsorption of heavy metals, biochar has good stability in the environment.