Preparation Of Modified Sepiolite And Adsorption Behavior To Formaldehyde

In recent years,the problem of indoor air pollution affecting human health has gradually attracted people's attention.Formaldehyde is the main source of indoor pollution.Long-term exposure will cause great harm to human body.The research of formaldehyde removal agent has become a hotspot.Mineral materials with adsorption properties are excellent raw materials for preparing formaldehyde removal agent.Sepiolite,as a low energy consumption and non-combustible environmental protection material,has unique pore structure,large specific surface area and strong adsorption capacity.It is an ideal raw material for formaldehyde removal agent.In this paper,three kinds of modified sepiolite were prepared from a sepiolite in Hunan Province:hydrochloric acid modified sepiolite,aluminium acid modified sepiolite and acid activated-hydrothermal modified sepiolite.Static adsorption experiments were carried out with formaldehyde as adsorbent to study the changes of mineralogical and physicochemical properties of sepiolite before and after modification and the adsorption behavior of modified sepiolite to formaldehyde.By studying the influence of different adsorption temperature,time and concentration on the dynamic adsorption of formaldehyde on sepiolite,the adsorption isotherm,adsorption thermodynamics and adsorption kinetics of Modified Sepiolite for formaldehyde were calculated.Finally,the adsorption isotherm and adsorption site of Sepiolite for formaldehyde gas were simulated by Sorption module in Materials Studio software,and the adsorption isotherm and adsorption site of Sepiolite for formaldehyde were analyzed.Mechanism.The main conclusions are as follows:The hydrochloric acid modified sepiolite with 15%hydrochloric acid had the best static adsorption effect on formaldehyde.The formaldehyde adsorption capacity was1.30 mg/g.The BET specific surface area of modified sepiolite increased from 71.50m~2/g of raw ore to 250.02 m~2/g,and the fibrous sepiolite increased after modification.The specific surface area of sepiolite modified by Aluminate increased to 213.25m~2/g,and the structure of sepiolite was loose and stratified.The modification results in more Si-OH bonds in sepiolite and increases the thermal stability of sepiolite.Adsorption of formaldehyde by modified sepiolite is a single molecular layer adsorption process,which is mainly physical adsorption,spontaneous and exothermic.Quasi-first-order kinetic model can be used to describe the adsorption of formaldehyde by sepiolite,which is a slow process.The diffusion model of sepiolite adsorbing formaldehyde particles shows that the adsorption rate is determined by both internal diffusion and membrane diffusion.By simulating the adsorption behavior of sepiolite to formaldehyde in Sorption module,it was found that all kinds of sepiolite have obvious adsorption effect on formaldehyde.The adsorption capacity of sepiolite modified by H~+is the largest.The adsorption isotherm conforms to Langmuir monolayer adsorption model,and there is no interaction between formaldehyde molecules.From the adsorption energy distribution curve and adsorption site map,it was found that formaldehyde adsorbed in sepiolite has only one adsorption site,that is,near the silicon-oxygen tetrahedron.The closer to the sepiolite structure,the smaller the energy is,the greater the energy is in the center of the channel,and the more easily formaldehyde is adsorbed there.