镧铁负载给水厂污泥复合材料对水中磷酸盐的吸附性能及机理

Performance and mechanism of phosphorus adsorption by lanthanum/iron-loaded drinking water treatment residues

采用沉淀法制备了镧铁负载给水厂污泥(DWTR)复合材料(LaFe-DWTR),对其微观形貌和理化性质进行了表征,考察了LaFe-DWTR对水中PO_(4)^(3-)-P的吸附等温线和吸附动力学,探讨了吸附剂投加量、pH和共存离子对PO_(4)^(3-)-P吸附效果的影响,并揭示了可能的吸附机理。结果表明:相比DWTR,镧和铁负载的DWTR比表面积和孔体积明显增加;当LaFe-DWTR投加量为2.0 g·L^(−1),PO_(4)^(3-)-P初始质量浓度为50 mg·L^(−1)时,LaFe-DWTR对的吸附等温线符合Sips模型,吸附动力学符合准二级动力学模型,说明吸附过程主要受化学吸附和颗粒内扩散控制;LaFe-DWTR在pH 2.0~11.0内对PO_(4)^(3-)-P的去除率均在90%以上,共存离子对LaFe-DWTR吸附的影响较小;LaFe-DWTR吸附的主要机理是配体交换。

In this study,a precipitation method was used to prepare lanthanum/iron-loaded drinking water treatment residues(LaFe-DWTR)composite material.Its micro-morphology and physicochemical properties were characterized,and the adsorption isotherms and kinetics of LaFe-DWTR towards PO_(4)^(3-)-P in water,as well as the effects of dosage,pH and coexisting ions on PO_(4)^(3-)-P adsorption effect,were investigated.Furthermore,the corresponding adsorption mechanism between LaFe-DWTR and was identified.The results showed that lanthanum/iron loading led to a significant increase of the specific surface area and pore volume of DWTR.At LaFe-DWTR dosage of 2.0 g·L^(−1) and initial concentration of 50 mg·L^(−1),the adsorption isotherm and kinetics could be well fitted by sips model and pseudo-second-order kinetic model,respectively.The adsorption process was mainly dominated by chemical adsorption and intra-particle diffusion.At pH 2.0~11.0,over 90% PO_(4)^(3-)-P in water could be removed by LaFe-DWTR.The coexisting ions had slight effect on adsorption.Ligand exchange was the main adsorption mechanism between LaFe-DWTR and PO_(4)^(3-)-P.