关键词: 甲醛;水泥基材料;吸附;扩散;双仓法

Abstract: Cement-based coatings with different thickness were prepared by adding heavy calcium carbonate , talc and rubber powder into white cement . The adsorption and diffusion behavior of formaldehyde in the coatings were experimentally studied by dual chamber method .Meanwhile , the phase, structure and surface groups of coating material were characterizated by X-ray diffraction (XRD), scanning electron microscopy ( SEM ) , mercury intrusion porosimetry ( MIP ) and nitrogen adsorption instrument .The process and mechanism of adsorption diffusion were discussed as well .The results show that the diffusion behavior of formaldehyde exists in the coatings with a diffusion critical depth of 3 mm, and the diffusion amount has a trend of linearly decreased with thickness .Moreover the formaldehyde can be adsorbed by the cement-based coatings , and the adsorption amount of formaldehyde in the coatings is changed accord with a first order increment exponential function with time and coating thickness .It can be founded from the testing results that the coating is porous .The total porosity of the coating is 36.5％, and the pore size is in the range of 3.6 nm to 212.7 μm with the meso-/macroporous structure.The porous structure of the coating is the main reason for its adsorption and diffusion ability .The absorption and diffusion of formaldehyde can be affected by the adsorption on mineral surface and the transition diffusion .

Key words: formaldehyde;cement-based material;adsorption;diffusion;dual chamber