Preparation Of Formaldehyde Capture Agent Loaded Halloysite And Its Application In Formaldehyde Removal Coatings

With the development of the modern interior decoration industry and people's attention to the environmental health,the demand of environmental friendly material for interior decoration is increasing,However,the common adhesive used in bamboo and wood decorative material might degrade and release formaldehyde during long term use due to its own instability.Formaldehyde removal coating with complex properties of physical adsorption and chemical fixation have better performance in reducing formaldehyde indoor release.Therefore,this study attempts to apply halloysite nanotubes(H)to the field of formaldehyde removal.Loading three formaldehyde removal agents(Ethyleneurea,2-Pyrrolidinone,Thiourea)were loaded into halloysite lumen to prepare a composite formaldehyde removal material.So formaldehyde could be physically absorbed due to its large specific surface area,and chemical fixated with its loaded formaldehyde removal agents.Thereby preparing a composite type formaldehyde removal material.The main research are urea intercalation halloysite process,formaldehyde capture agent loading process and formaldehyde removal coating preparation process.Besides,the effect and mechanism of effect and mechanism of liquid phase formaldehyde removal,gas phase formaldehyde removal effect,and functional aldehyde removal coatings are studied.This study explores the application of loading into halloysite nanotubes and preparing formaldehyde removal coating,provides a new way to develop formaldehyde removing coatings for the development of bamboo and wood decorative materials.The main results are listed as follows:(1)Urea intercalation of halloysite and loading of formaldehyde removal agentsFour methods including magnetic stirring,reflux heating,ball milling and ultrasonic treatment were used to study the intercalation process of urea in halloysite.The urea intercalation effect of the HU-MS process is the best,with a intercalation rate of 68.28% and the layer space of the halloysite increased from 0.723 nm to 1.074 nm.Scanning electron microscopy showed that only the magnetic stirring method did not cause mechanical damage to the microstructure of the halloysite nanotubes.Four methods including magnetic stirring,reflux heating,vacume loaded and ultrasonic treatment were used to load formaldehyde removal thiourea(T)in urea-modified halloysite.The TG results showed that the vacuum load(HUT-VL)is better.A superior loading content of thiourea(21.87%)is obtained with the concentration of thiourea 1 mol/L However,when the concentration of thiourea is is doubled to 2 mol/L,loading content of thiourea only increased by 5.54%.As a result,the optimized process of urea intercalation and agent loading is first through vacume then loaded with the concentration of 1 mol/L.(2)Comparison of nanocomposites loaded with different formaldehyde removal agents and their formaldehyde removal abilities in liquid phaseThree kinds of formaldehyde removal agents(T,P,E)are loaded by vacuum method to prepared HUT,HUE and HUP.The TG results showed that the loading content are significantly improved by the urea intercalation.The loading content were 0.29 mol/100 g(HUT),0.44 mol/100 g(HUE),and 0.32 mol/100 g(HUP),The BET measurement showed that the specific surface area and pore volume decreased due to the formaldehyde removal agents filled the halloysite.The optimal formaldehyde-removing efficiency of HUT,HUE and HUP in the liquid were 424.73 mg/mol,768.7 mg/mol and 55.0 mg/mol respectively.With a lower addition amount of nanocomposites,the nanocomposites had better dispersion and high formaldehyde-removing efficiency.The maximum formaldehyde-removing efficiency of HUT,HUE and HUP were 65 %,60 % and 22 % respectively.Data analysis revealed that the liquid adsorption models of HUE and HUT fitted to the Freundlich model which indicated that nanocomposites could promote the absorption of formaldehyde.The dynamic adsorption model were fitted the second-order dynamic model which indicated that the nanocomposites could chemical.(3)Evaluation of formaldehyde-removing efficiency and coating performance of formaldehyde removal coatingsThe addition of nano-compsites willwill decrease the gloss degree of the coating and appear matte color.The contact Angle test results showed that the addition of nanocomposite will slightly reduce the initial contact angle of water.At the same time,The adhesion of coating were also slightly reduced,while the hardness of the coating was increased with the addition of nanocomposites.The results showed that amount brush has little effect on the effect of formaldehyde-removing and the amount of addition has a great influence on the effect of formaldehyde-removing.Within the 24 hour formaldehyde-removing test,when the amount of addition is 6 %,the rate of formaldehyde-removing is 64 %.The optimized coating condition is 30 g/m2 with the additive amount of 6% to obtain a better formaldehyde removal performance..