改性生物炭对水体中氮和磷共去除:改性方法和吸附机制

Co-removal of Nitrogen and Phosphate from Water by Modified Biochar:Modification Methods and Adsorption Mechanisms

水体中氮和磷的共去除和资源化利用一直是研究的热点,生物炭应用为其提供了新的选择。综述了改性生物炭对氮和磷的共去除,重点聚焦在改性方法和吸附机制。生物炭改性方法主要为矿物质的负载,具体可分为镁改性、铁改性、双金属改性、其它矿物质改性等。改性目的是增加生物炭的比表面积和孔隙结构;强化静电作用;加强离子交换能力;增强配合能力;促进沉淀作用,特别是促进鸟粪石结晶反应,回收资源。改性生物炭对氮和磷共去除的机制涉及:更高比表面积和发达孔隙结构提供更多的吸附点位;表面电性和氮磷之间的静电作用;矿物质组分与氮磷之间的离子交换作用;多种官能团能与氮磷产生配合作用;矿物组分能与氨氮和磷酸盐发生沉淀作用,特别是鸟粪石化学沉淀。未来的研究方向是:创新生物炭的改性方法;借助先进的手段揭示共去除的微观机制;回收氮磷制备缓释肥;改性生物炭在实际水体中的应用。

Co-removal and resource utilization of nitrogen and phosphate in water had become a research hotspot,and biochar applications provided a new options.In this study,the co-removal of nitrogen and phosphate by modified biochar was summarized,focusing on the modification methods and adsorption mechanisms.The modification methods of biochar were mainly focused on the loading of minerals,including magnesium modification,iron modification,bimetallic modification,and other mineral modification methods.The purposes of modification were increasing the specific surface area and pore structure of biochar;enhancing electrostatic action;strengthening ion exchange capacity;enhancing complexation ability;promoting precipitation,especially promoting struvite crystallization reaction to recycle resources.The co-removal mechanism of nitrogen and phosphorus from modified biochar involves:its higher specific surface area and developed pore structure which provides more adsorption sites;its surface electricity causing electrostatic interaction;its mineral components leading to ion exchange;many functional groups bringing complexation;its mineral components producing precipitates,especially struvite chemical precipitation.The future research directions are:innovating the modification methods of biochar;uncovering the microscopic mechanisms of co-removal using advanced techniques;recycling of nitrogen and phosphate to prepare slow release fertilizer;application of modified biochar in actual water.