Preparation And Application Of Ca-MOF/ABS/TPU Composite Based On 3D Printing

Metal-organic framework materials（MOFs）is a new type of porous material with large specific surface area,high porosity,adjustable pore size,easy chemical modification,and diverse structural composition.MOFs have a promising potential application in the field of pollutant adsorption and separation.However,the crystallinity of MOFs causes its form of powders,which greatly limits their practical application.Therefore,consolidating MOFs into a monolithic material and promoting their reusability becomes a critical topic.3D printing technology has become one of the important technologies to realize the deviceization of MOFs due to its device-based and designable characteristics.The work reports a new method to realize the deviceization of MOFs composites based on 3D printing technology.Ca SiO₃ was introduced in ABS/TPU melted blend in a twin-screw extruder,and Ca SiO₃/ABS/TPU filament was extruded on a mini filament system for printing.MOFs were loaded directly on the surface of acetone-etched ABS/TPU/Ca SiO₃ 3D printed skeleton via an in-situ growth method.Various characterizations were used to prove the successful preparation of Ca-MOF/ABS/TPU composites,and the adsorption behavior of methylene blue（MB）dyes and three heavy metal ions(Cu²⁺,Co²⁺and Pb²⁺)was explored.And the adsorption mechanisms were investigated via adsorption kinetics,adsorption isotherm and other models.This work provided a new strategy for the application of MOFs in the environmental field.（1）Firstly,the Ca SiO₃/ABS/TPU composite filaments were prepared by melt blending technology,and the in-situ growth method was carried out to synthesize Ca-MOF/ABS/TPU composites.The influence of Ca SiO3 contents and 3D-printed models for the structure and performance of the composites was explored.Various characterizations for the composites have preformed including SEM,EDS,IR,XRD,TG and BET.The results show that the Ca-MOF was successfully loaded on the surface of the 3D skeletons.The specific surface area of Ca-MOF/ABS/TPU composite（with 40 content of Ca SiO₃）increases by about two times compared with that of ABS/TPU/Ca SiO₃ composite.And the corresponding MB adsorption is increased from 35%to 86%.The adsorption performance of the 3D printing spiral skeleton is better than that of the square,revealing the advantage of the 3D printing for its designable.（2）Secondly,the Ca-MOF/ABS/TPU spiral skeleton was employed to adsorb MB.The adsorption behaviors and influencing factors were studied via the adsorption kinetics,isotherm and thermodynamics.And the adsorption mechanisms were investigated through analyzing the micro-morphologies and crystal structure variation of spiral skeleton before and after adsorption.The results show that Ca-MOF/ABS/TPU spiral skeleton have a relatively stable performance for MB adsorption at p H=3～10.The adsorption is a spontaneous exothermic process,follows pseudo-second-order kinetic model.Multimolecular layer adsorption with uneven adsorption heat on an ordered surface is occurred on the spiral skeleton.The spiral skeleton shows a good reusibility with 70%removal ratio remains at sixth runs.（3）The adsorption performances of Cu²⁺,Co²⁺and Pb²⁺on the Ca-MOF/ABS/TPU spiral skeleton were conducted.The results show that removal rate of Cu²⁺,Co²⁺and Pb²⁺with an initial concentration of 100 mg/L on the spiral skeleton are above 98%.The removal ratio of Pb²⁺on the spiral skeleton remains above 99%when p H between 2 and 6.However,the adsorption performance were impact due to the hydrolysis of metal ions when p H≥6.And the smaller hydrolysis constant of Cu²⁺makes it the most affected.The changes of p H or the introduction of other metal ions decrease the adsorption capacity of Co²⁺on the spiral skeleton.The results of competitive adsorption for heavy metal ions show that the selective adsorption of Ca-MOF/ABS/TPU spiral skeleton for heavy metals is Cu²⁺>Pb²⁺>Co²⁺.Adsorption kinetics results indicating that the adsorption process of spiral skeleton for Cu²⁺and Co²⁺is dominated by chemisorption,while that for Pb²⁺is belonged to physisorption.The results of morphologies and structures change of the spiral skeleton before and after adsorption revealing that the adsorption mechanism of Cu²⁺,Co²⁺and Pb²⁺on the spiral skeleton is belongs to the ion exchanges.