摘要
为了提高天然聚合物凝胶的力学性能,并解决粉末状MOF材料在吸附水体中Cu(Ⅱ)方面的局限性,采用ZIF-67和聚乙烯醇/海藻酸钠(PVA/SA)水凝胶,通过原位生长法,设计并制备了MOF和聚合物复合水凝胶材料。通过FTIR、SEM、Brunauer-Emmett-Teller(BET)、XPS和XRD对合成的水凝胶球进行了表征,证实了MOF材料在PVA/SA水凝胶球上的原位生长。采用氮吸附-解吸等温线测量了复合水凝胶的比表面积和孔径,分别为613.72 m^(2)·g^(-1)和2.44 nm。研究了复合水凝胶对水体中Cu(Ⅱ)的吸附特性、热力学和动力学模型以及吸附机制。实验结果表明,Cu(Ⅱ)的最佳吸附pH值为5,最大吸附容量为128.4 mg·g^(-1),分别是普通SA和PVA/SA水凝胶的3.3倍和1.8倍。吸附过程更符合Freundlich等温线模型(相关系数R^(2)=0.96~0.99),吸附动力学更符合拟二阶模型(R^(2)=0.973~0.998)。热力学分析表明,吸附过程是吸热且自发的,温度升高更有利于吸附过程。复合材料的主要吸附机制是络合、阳离子交换和物理吸附。这是由于吸附过程中-OH和-COOH基团的参与以及Ca(Ⅱ)和Cu(Ⅱ)的离子交换作用。循环吸附分析实验表明,PVA/SA@ZIF-67在5次吸附循环后仍能保持90%以上的原始吸附容量。在不同的水样环境中对Cu(Ⅱ)的选择性去除进行了试验。PVA/SA@ZIF-67对Pb(Ⅱ)和Cu(Ⅱ)的吸附性能远远优于Cd(Ⅱ)、Zn(Ⅱ)、Ni(Ⅱ)、Mn(Ⅱ)。
In this study,an effort was made to enhance the mechanical properties of natural polymer gels and address the limitations of powdered MOF materials in the adsorption of Cu(Ⅱ)in water.To this end,a MOF and polymer composite hydrogel material was designed and prepared through the use of ZIF-67 and polyvinyl alcohol/sodium alginate(PVA/SA)hydrogels via a situ grow method.The synthesized hydrogel spheres were characterized by FTIR,SEM,Brunauer-Emmett-Teller(BET),XPS and XRD,confirming the in-situ growth of MOF material on PVA/SA hydrogel spheres.The specific surface area and pore size of the composite hydrogel were measured using nitrogen adsorption-desorption isotherm to reach 613.72 m^(2)·g^(−1)and 2.44 nm,respectively.The adsorption characteristics,thermodynamic and kinetic modelling and adsorption mechanism of Cu(Ⅱ)in water by composite hydrogels were investigated.The experimental results demonstrated that the optimal adsorption pH of Cu(Ⅱ)was 5,with a maximum adsorption capacity of 128.4 mg·g^(−1),which was 3.3 and 1.8 times that of ordinary SA and PVA/SA hydrogels,respectively.The adsorption process was found to be more consistent with the Freundlich isotherm model(Correlation coefficient R^(2)=0.96-0.99),while the adsorption kinetics was more consistent with the pseudo-secondorder model(R^(2)=0.973-0.998).Thermodynamic analysis revealed that the adsorption process was endothermic and spontaneous,and that increasing the temperature is more conducive to the adsorption process.The main adsorption mechanisms of composite materials are complexation,cation exchange and physical adsorption.This is due to the participation of−OH and−COOH groups and the ion exchange of Ca(Ⅱ)and Cu(Ⅱ)in the adsorption process.PVA/SA@ZIF-67 can still maintain more than 90%of its original adsorption capacity after 5 adsorption cycles,as demonstrated by cyclic adsorption analysis experiments.The selective removal of Cu(Ⅱ)was tested in different water sample environments.The adsorption performance of PVA/SA@ZIF-67 for Pb(Ⅱ)and Cu(Ⅱ)is much better than Cd(Ⅱ),Zn(Ⅱ),Ni(Ⅱ)and Mn(Ⅱ).
作者
杨金川
张国俊
付华
YANG Jinchuan;ZHANG Guojun;FU Hua(College of Chemical Engineering,Qinghai University,Xining 860016,China)
出处
《复合材料学报》
北大核心
2025年第7期3963-3973,共11页
Acta Materiae Compositae Sinica
