School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
Sci Total Environ. 2022 Jul 20;831:154845. doi: 10.1016/j.scitotenv.2022.154845. Epub 2022 Mar 28.
As a porous and carbon material, biochar is focused on respectively in sequestrating carbon and stabilizing metals in soil, while few studies attempted to design biochar for simultaneously achieving these two targets. This study proposed to produce phosphorus-composite biochar for synchronously enhancing carbon sequestration and heavy metals immobilization. Two phosphorus materials from tailings, Ca(HPO) and Ca(PO)(OH), were selected as modifier to load into biomass prior to pyrolysis. Results showed that incorporating P not only increased pyrolytic C retention in biochar by 36.1-50.1%, but also obtained biochar with higher stability by chemically formation of COP, C-PO and C-PO. After 90-day incubation with soil, more C was sequestrated in the P-biochar amended soil (59.6-67.0%) than those pristine biochar (43.2-46.6%). Highly soluble Ca(HPO) was more efficient than Ca(PO)(OH) in this regard. Meanwhile, these P-composite biochar exhibited more Pb/Cd immobilization (31.3-92.3%) compared with the pristine biochar (9.5-47.2%), which was mainly due to the formation of stable precipitates Pb(PO)Cl and Cd(PO), especially for Ca(PO)(OH) modification. Additionally, P-composite biochar "intelligently" altered soil microbial community, i.e., they suppressed Actinobacteria proliferation, which is correlated to carbon degradation, while promoted Proteobacteria growth, facilitating phosphate dissolution for ready reaction with heavy metals to form precipitate, benefiting the Pb and Cd immobilization. A dual functions biochar was engineered via simply loading phosphorous prior to pyrolysis and simultaneously enhanced carbon sequestration and heavy metal immobilization.
作为一种多孔碳质材料，生物炭主要集中在固碳和稳定土壤中的金属方面，而很少有研究尝试设计生物炭以同时实现这两个目标。本研究提出制备磷复合生物炭，以同时提高碳固存和重金属固定。选择两种来自尾矿的磷材料，Ca(HPO)和 Ca(PO)(OH)，作为改性剂，在热解前负载到生物质中。结果表明，引入 P 不仅可以使生物炭中热解 C 的保留量增加 36.1-50.1%，而且通过 COP、C-PO 和 C-PO 的化学形成获得了稳定性更高的生物炭。与原始生物炭相比（43.2-46.6%），在 90 天的土壤培养后，添加 P 生物炭的土壤中固存了更多的 C（59.6-67.0%）。在这方面，高可溶性 Ca(HPO)比 Ca(PO)(OH)更有效。同时，与原始生物炭相比（9.5-47.2%），这些 P 复合生物炭表现出更高的 Pb/Cd 固定化率（31.3-92.3%），这主要是由于形成了稳定的沉淀 Pb(PO)Cl 和 Cd(PO)，特别是 Ca(PO)(OH)改性。此外，P 复合生物炭“智能”地改变了土壤微生物群落，即抑制了与碳降解相关的放线菌的增殖，同时促进了有利于磷酸盐溶解的变形菌的生长，以便与重金属形成沉淀，有利于 Pb 和 Cd 的固定化。通过在热解前简单地负载磷来设计双功能生物炭，同时提高了碳固存和重金属固定化。
