Adsorption of heavy metals by biochar adsorbents can reduce their bioavailability and mobility. However, the effects of the biodegradation processes of raw material before biochar preparation on adsorption remain unclear. This study utilized the degradation products at different stages of the compost to produce biochars and investigated their adsorption property. Compared to the virgin biochar (IBC) prepared from untreated compost, the biochar (EBC and LBC) prepared from the sample collected by the biodegradation process had more robust adsorption properties. Furthermore, the adsorption capacity of biochar (LBC) prepared from the sample collected in the later biodegradation process was approximately 50% higher than that of biochar (EBC) prepared from the sample collected in the early phase. LBC had more oxygen-containing functional groups, more ion exchange sites, and carbonate ions, improving the adsorption capacity by 100% compared with IBC. The BET surface area of LBC was approximately four times higher than that of IBC and 25% more than EBC. Moreover, the dominant adsorption mechanism of LBC is the formation of insoluble Cd-mineral complexes (cadmium carbonate) with the inorganic. The increase in pH also facilitated Cd (II) precipitation. This study highlighted that appropriate biodegradation before biochar preparation from manure mix is an effective and energy-saving method to enhance the ability of biochar to adsorb heavy metals.

生物炭吸附剂吸附重金属会降低其生物利用度和流动性。然而，生物炭制备前原料的生物降解过程对吸附的影响仍不清楚。本研究利用堆肥不同阶段的降解产物生产生物炭，并研究其吸附性能。与由未经处理的堆肥制备的原始生物炭 (IBC) 相比，由生物降解过程收集的样品制备的生物炭（EBC 和 LBC）具有更强的吸附性能。此外，吸附能力从后期生物降解过程中收集的样品制备的生物炭 (LBC) 比从早期阶段收集的样品制备的生物炭 (EBC) 高约 50%。LBC具有更多的含氧官能团、更多的离子交换位点和碳酸根离子，与IBC相比吸附能力提高了100%。LBC 的 BET 表面积大约是 IBC 的四倍，比 EBC 高 25%。此外，LBC 的主要吸附机制是与无机物形成不溶性镉矿物复合物（碳酸镉）。pH 值的增加也促进了 Cd (II) 的沉淀。该研究强调，在从粪便混合物制备生物炭之前进行适当的生物降解是增强生物炭吸附重金属能力的有效且节能的方法。