Li Zhiwei, Huang Jingxin, Zhang Weizhen, Yu Hao, Wang Yin
State Key Laboratory of Regional and Urban Ecology, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
State Key Laboratory of Advanced Environmental Technology, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
Toxics. 2025 Jul 9;13(7):577. doi: 10.3390/toxics13070577.
Eutrophication driven by nitrogen and phosphorus discharge remains a critical global environmental challenge. This study developed a sustainable strategy for synergistic nutrient removal and recovery by fabricating MgO-coated biochar (Mg-MBC600) through co-pyrolysis of municipal sludge and sunflower stalk (300-700 °C). Systematic investigations revealed temperature-dependent adsorption performance, with optimal nutrient removal achieved at 600 °C pyrolysis. The Mg-MBC600 composite exhibited enhanced physicochemical properties, including a specific surface area of 156.08 m/g and pore volume of 0.1829 cm/g, attributable to magnesium-induced structural modifications. Advanced characterization confirmed the homogeneous dispersion of MgO nanoparticles (~50 nm) across carbon matrices, forming active sites for chemisorption via electron-sharing interactions. The maximum adsorption capacities of Mg-MBC600 for nitrogen and phosphorus reached 84.92 mg/L and 182.27 mg/L, respectively. Adsorption kinetics adhered to the pseudo-second-order model, indicating rate-limiting chemical bonding mechanisms. Equilibrium studies demonstrated hybrid monolayer-multilayer adsorption. Solution pH exerted dual-phase control: acidic conditions (pH 3-5) favored phosphate removal through Mg(PO) precipitation, while neutral-alkaline conditions (pH 7-8) promoted NH adsorption via MgNHPO crystallization. XPS analysis verified that MgO-mediated chemical precipitation and surface complexation dominated nutrient immobilization. This approach establishes a circular economy framework by converting waste biomass into multifunctional adsorbents, simultaneously addressing sludge management challenges and enabling eco-friendly wastewater remediation.
氮磷排放导致的富营养化仍然是一项严峻的全球环境挑战。本研究通过城市污泥和向日葵秸秆在300 - 700°C下共热解制备氧化镁包覆生物炭（Mg - MBC600），开发了一种协同去除和回收营养物质的可持续策略。系统研究揭示了温度依赖性吸附性能，在600°C热解时实现了最佳营养物质去除。Mg - MBC600复合材料表现出增强的物理化学性质，包括比表面积为156.08 m/g和孔体积为0.1829 cm/g，这归因于镁诱导的结构改性。先进表征证实氧化镁纳米颗粒（约50 nm）在碳基质中均匀分散，通过电子共享相互作用形成化学吸附的活性位点。Mg - MBC600对氮和磷的最大吸附容量分别达到84.92 mg/L和182.27 mg/L。吸附动力学符合准二级模型，表明限速化学键合机制。平衡研究表明为混合单层 - 多层吸附。溶液pH发挥双相控制作用：酸性条件（pH 3 - 5）有利于通过Mg(PO)沉淀去除磷酸盐，而中性 - 碱性条件（pH 7 - 8）通过MgNHPO结晶促进NH吸附。XPS分析证实氧化镁介导的化学沉淀和表面络合主导营养物质固定。该方法通过将废弃生物质转化为多功能吸附剂建立了循环经济框架，同时应对污泥管理挑战并实现环保型废水修复。
