铁盐活化污泥生物炭对水中磷的吸附效能与机理

Adsorption Efficiency and Mechanisms of Phosphorus Removal from Water Using Iron Salt-activated Sludge Biochar

污泥热解生物炭是市政污泥资源化利用的方式之一,其在污水处理中的应用备受关注。碱性条件下,采用亚铁离子和铁离子对预处理后污泥在N_(2)氛围下热解炭化,制备出磁性污泥生物炭(MSB),探讨MSB样品吸附水中磷的效能与机理。结果表明,热解温度为MSB磷吸附效能的关键控制因素,250℃下制备MSB样品(MSB250)的磷吸附效果最佳,平衡吸附量为4.6 mg/g。偏酸性条件有利于MSB250的磷吸附,pH低于3会导致样品的铁泄漏,最佳吸附反应条件是pH为4、温度为25℃。MSB250的吸附等温线符合Freundlich方程,吸附热力学分析表明,磷在MSB250上的吸附过程是自发、吸热的,MSB250的表面活性官能团与磷酸根基于路易斯酸碱作用生成络合物,可推断MSB250去除磷的主要机理为静电吸引。

Sludge pyrolysis biochar represents a significant method for the resource utilization of municipal sludge,and its application in wastewater treatment has garnered considerable attention.Magnetic sludge biochar(MSB)was synthesized through the pyrolysis and carbonization of pretreated sludge with ferrous and ferric ions in a nitrogen atmosphere under alkaline conditions.The adsorption efficiency and mechanisms of MSB samples for phosphorus removal from water were systematically investigated.The pyrolysis temperature was a critical parameter influencing the phosphorus adsorption efficiency of MSB.Among the samples,MSB prepared at 250℃(MSB250)exhibited the highest phosphorus adsorption performance,with an equilibrium adsorption capacity of 4.6 mg/g.Acidic conditions were conducive to the adsorption of phosphorus by MSB250,with a pH below 3 resulting in iron leaching from the sample.The optimal conditions for the adsorption were a pH of 4 and a temperature of 25℃.The adsorption isotherm of MSB250 aligned with the Freundlich equation.Thermodynamic analysis of the adsorption process indicated that phosphorus adsorption onto MSB250 was both spontaneous and endothermic.Furthermore,the surface-active functional groups on MSB250 interacted with phosphoric acid to form a complex through Lewis acid?base interactions.It was concluded that the predominant mechanism for phosphorus removal by MSB250 involved electrostatic attraction.