Preparation Of Attapulgite Composite Material And Its Effect On Purifying Formaldehyde At Room Temperature

In this paper,attapulgite clay from four different producing areas was used to investigate its formaldehyde removal performance at room temperature.Then,the attapulgite clay from Guanshan was purified and calcined(100?300?)to study the effect of calcination temperature on the formaldehyde removal performance of the material.Finally,attapulgite was used as a carrier to support BiOI,and the photocatalytic composites were prepared by calcination at 100?400?,and the effect of formaldehyde removal under visible light was studied.The physicochemical properties of the material and the reaction mechanism of formaldehyde removal were investigated by XRD,BET,XPS and in-situ infrared techniques.The results show that:(1)Among the four kinds of attapulgite clays,the static/dynamic removal effect of formaldehyde of Guanshan attapulgite clay is the best,which is 0.639 mg·g^-1 and 1.436 mg·g^-1.According to the characterization,the number of structural hydroxyl groups,surface hydroxyl groups and the high specific surface area of the material are the main factors affecting the performance of formaldehyde removal.(2)By thermal activation of attapulgite,the material's phase and structure did not change significantly.The static/dynamic removal of formaldehyde by attapulgite after thermal activation at 250?reached the maximum.When the thermal activation temperature reached 300?,the static/dynamic removal of formaldehyde by Pal-300 was less than that by Pal-250.The mechanism of removing formaldehyde by Pal-250 includes both physicochemical adsorption and catalytic oxidation reaction.The formaldehyde adsorbed on the surface of attapulgite can be partially mineralized into methylene dioxymehtylene and formate through the hydroxyl mineralization on the surface of attapulgite at room temperature.Oxygen in the air can generate reactive oxygen species on the surface of attapulgite and further convert methylene dioxygen to formate.(3)through different calcination temperature BiOI/attapulgite,the sample going to in addition to formaldehyde in condition of visible light photocatalytic activity increased first and then,when the calcination temperature is 300?,the composite material surface produce more oxygen vacancy,thus improve the photoproduction electronic(e^-)and holes(h⁺),the separation efficiency and to formaldehyde adsorption activation.The degradation rate of formaldehyde reaches 84.44%,and part of BiOI in the composite material calcined at 400?will be oxidized to Bi₂O₃,which reduces the formaldehyde removal performance of the material and the degradation rate is 70%.