Study On Preparation Of Modified Sepiolite And Adsorption Properties Of Formaldehyde

The indoor formaldehyde pollution problem is a very serious environmental problem.Traditional formaldehyde treatment includes thermal catalytic oxidation,photocatalytic oxidation and other methods.These methods have high cost,high energy consumption and no practical application significance.Therefore,the development of green,environmently friendly and efficient formaldehyde adsorbents is of great significance.In this paper,we prepare 3-aminopropyltriethoxysilane modified sepiolite（APS/Sep）and p-aminobenzoic acid modified sepiolite（PABA/Sep）successfully.APS/Sep and PABA/Sep have much higher formaldehyde adsorption performance than raw sepiolite.In this paper,3-aminopropyltriethoxysilanr was supported on the surface of sepiolite by heating and refluxing successfully.Among them,the best reflux temp erature is 110℃,the best reflux time is 24h and the best loading of 3-aminopro pyltriethoxysilane is 0.4g/g.At the initial formaldehyde concentration of 10mg/m³,the amount of adsorbent is 5g,the adsorption of formaldehyde by APS/Sep basically reaches equilibrium at 8h and the removal rate of formaldehyde can reach 96.36%.The maximum unit formaldehyde adsorption amount of APS/Sep prepared in this paper is 413.2ug/g.According to the calculation of adsorption kinetics and adsorption thermodynamics,the adsorption of formaldehyde by APS/Sep conforms to the quasi-second-order kinetics model and Langmuir model.In this paper,p-aminobenzoic acid was loaded on the sepiolite surface by agitation and dipping successfully.The optimal agitation and dipping time is 10h,the optimal agitation temperature is 20℃ and the optimal p-aminobenzoic acid loading is 0.3g/g.At an initial formaldehyde concentration of 30mg/m³ and an adsorbent dosage of 5g,the adsorption of formaldehyde by PABA/Sep basically reached equilibrium at 6h hours and the formaldehyde removal rate reaches 98.05%.The maximum unit formaldehyde adsorption amount of PABA/Sep prepared in this paper is 937.1ug/g.According to the calculation of adsorption kinetics and adsorption thermodynamics,theadsorption of formaldehyde conforms to the quasi-second-order kinetics model and the Langmuir model.The adsorption of formaldehyde on the surface of APS/Sep and PABA/Sep is controlled by the chemical active sites,which belongs to the monolayer adsorption with uniform active sites and is a spontaneous endothermic process.According to SEM、TEM、BET、XRD、FTIR and other characterizations,the specific surface area of sepiolite has been reduced to a certain extent due to the loading of 3-aminopropyltriethoxysilane and p-aminobenzoic acid.Through Fourier infrared spectroscopy（FTIR）analysis,it can be seen that in the FTIR spectrum of APS/Sep,the-OH vibration peaks at 3340cm^-1 and 1638cm^-1 disappear,which shows that the introduction of 3-aminopropyltriethoxy silane breaks the original-OH bond in sepiolite and forms new vibration peaks at 2850cm^-1 and3700cm^-1,which shows that the 3-aminopropyltriethoxysilane modified sepiolite was successfully prepared.After p-aminobenzoic acid was loaded,the vibration peak intensity at 1030cm^-1 and 3440cm^-1 decreased,which indicated that p-aminobenzoic acid changed the structure of sepiolite to a certain extent,and thenew vibration peaks appeared at 1200cm^-1,1310cm^-1,1440cm^-1and 1570cm^-1,in dicate that p-aminobenzoic acid was successfully loaded on the sepiolite surface.