Study On The Structure And Performance Of Attapulgite-modified PVDF Blended Dehumidification Membran

Membrane dehumidification is widely used due to its high efficiency and operability,but adding moisture-absorbing agent to the membrane dehumidification makes it easy for the moisture-absorbing agent to flow out from the surface of the membrane during use,resulting in the decrease of hygroscopic performance Therefore,in this paper,PVDF was used as the skeleton support structure,attapulgite（ATP）was used as the aqueous solution channel of CaCl₂ hydrolysate and the polymer reinforcement material was also used,and CaCl₂ was used as the main moisture adsorption agent.PVDF dehumidifying membranes modified with attapulgite were prepared by solvent volatilization induced phase separation（SEIPS）.The effects of different ATP and CaCl₂ contents on the structure and properties of the membranes were studied.The membranes were characterized by scanning electron microscopy（SEM）,porosity test,contact angle test,hygroscopicity test,etc.The results showed that with the increase of ATP content,the membrane structure became loose and porous,the structure of ATP fiber rod attached by spherulites increased,and the porosity increased gradually,the highest was 77%.With the increase of CaCl₂ content,the intergranular space increased and the porosity increased.When CaCl₂ increased to30wt%of the polymer,the membrane structure became dense,the adhesion between spherulites occurred,and there was a tendency to change into cellular pores.The moisture management ability showed that the addition of ATP can improve the hydrophilicity of the dehumidification membrane,and the permeability of the membrane was improved,and the moisture adsorption capacity and initial moisture adsorption rate were gradually increased.When ATP was added to 10%of the polymer,the maximum hygroscopicity and hygroscopicity rate were 0.876 g·g^-1 and 0.056 g·g^-1.min^-1.Low content of CaCl₂ was beneficial to improve the hydrophilicity and water vapor infiltration and adsorption of the membrane,while high content of CaCl₂densified the membrane structure,which was not conducive to water vapor infiltration and reduced the hygroscopicity.With the increase of ATP content and CaCl₂ content,the tensile properties of the dehumidification membrane increased.The addition of ATP makes the dehumidification membrane had the function of adsorbing formaldehyde,and the adsorption capacity can reach 73.6 mg·g^-1.In order to further improve the hygroscopic performance of dehumidification membrane and improved the loss of CaCl₂,firstly,magnetic attapulgite（MATP）was prepared by chemical coprecipitation method.The structure and magnetic properties of MATP were characterized by SEM,Fourier infrared spectroscopy,X-ray diffraction,Vibration sample magnetometer,etc.The results showed that Fe₃O₄ nanoparticles were evenly adsorbed on the surface of ATP and exhibited good magnetic properties.Secondly,MATP modified PVDF dehumidification membrane was prepared by magnetic field induction and SEIPS method,and the structure and properties of the membrane were characterized by SEM,porosity test,X-ray element analyzer（EDX）,hygroscopicity test,hydrolytic performance test and anti-biological contamination test.The results showed that PVDF spherulites were concentrated by magnetic field,the porosity of spherulites was increased,the structure of ATP on spherulites was regular orientation,and the hygroscopicity was improved.The hygroscopicity and hygroscopicity were 0.986 g·g^-1 and 0.060 g·g^-1.min^-1,respectively.At the same time,it has good tensile properties.Finally,the hydrolyzing performance of the dehumidification membrane was studied.It was proved that the addition of ATP and magnetic field could slow down the loss of CaCl₂ in the membrane,and the loss rate of CaCl₂ was reduced by about 10%.In addition,the dehumidification membrane with MATP had better resistance to biological contamination,which expanded the application range of dehumidification membrane.