Preparation Of Au/MnO_x-loaded Porous Composite Fiber Membrane And Its Catalytic Purification Of Formaldehyd

Formaldehyde(HCHO)is one of the most common indoor volatile organic pollutants.Efficient HCHO elimination technology has been widely concerned.Among different methods of HCHO removal,catalytic oxidation under ambient temperature is an effective method.Recently,the manganese oxide nanoparticles(MnO_xNPs)catalysts loaded on the surface of fibers have been widely studied for removal of HCHO.However,these catalysts face many problems such as of active sites and weak mechanical stability,some NPs could even be lost in the airflow and pollute the environment.Therefore,it is of desirable to find a general method to load MnO_x NPs efficiently and stability while keeping their high activity.In addition,the particle size,dispersion degree and doping of other metals of MnOx nanoparticles are also crucial to their catalytic performance.In this work,designed a novel Au/MnO_x/m PVB porous fiber membrane with a microreactor-like structure by electrospinning.The macropores were uniformly distributed inside the fiber,and Au/MnO_x NPs were loaded on the inner wall of the pores.This structure can minimize the numbers of the covered Au/MnO_x NPs active sites and improve the stability of the Au/MnO_x NPs immobilized on the supports.In addition,the fibers were modified with amino functional groups which could absorb HCHO molecules.As a result,the HCHO concentration can be increased in the microreactor by adsorption,and the activity of the catalyst can be enhanced under the synergistic effect of adsorption and catalysis.The main conclusions are as follows:(1)MnO_x@PMAA and Au/MnO_x@PMAA composite microspheres were prepared by in-situ reduction using PMAA microspheres as templates.The morphology,particle size distribution,chemical composition and crystal structure of the composite microspheres were studied.The results showed that when the molar ratio of Au:Mn:PMAA was 1:8:40,the microspheres had good morphology and the catalyst nanoparticles did not agglomerate.(2)Amino-modified polyvinyl butyral(m PVB)nanofiber membranes were prepared by dehydration condensation and electrospinning,and the optimal spinning parameters of m PVB were studied.Simultaneously,the indoor environment was simulated,and the adsorption performance of as-prepared m PVB fiber membrane on low-concentration HCHO was studied.The results showed that when the APTES content was 30%,the m PVB had the best adsorption performance for formaldehyde,and the adsorption efficiency was 71.3%.(3)MnO_x/m PVB and Au/MnO_x/m PVB porous composite fiber membranes were prepared by blending spinning and template removal,and the morphological characteristics of the composite fiber membranes were studied.At the same time,the catalytic oxidation performance of two kinds of porous fiber membranes on HCHO under different catalyst loading,initial HCHO concentration,humidity and other conditions was studied.The results showed that the Au/MnOx/m PVB porous composite fibers exhibited high efficiency(92.6%)and long-term stability for the oxidative decomposition of 1.0 mg/m~3(i.e.0.8 ppm)HCHO at room temperature.