Sorption and diffusion properties of untreated and thermally modified beech wood dust

Jerzy Majka,Tomasz Rogoziński,Wiesław Olek

doi:10.1007/s00226-021-01346-x

Jerzy Majka, Tomasz Rogoziński + Show 1 more

Open Access

https://doi.org/10.1007/s00226-021-01346-x

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Abstract

Dynamic water vapor sorption experiments were carried out using beech wood dust (from untreated and thermally modified wood) of two-particle sizes, (< 25 and 80–250 µm), obtained from abrasive sanding. Sorption isotherms were parameterized with the GAB and GDW models. Dust from thermally modified wood had significantly lower equilibrium moisture content compared to dust from untreated material, due to the reduction in primary sorption sites in treated material. The observed changes were quantified by the coefficients of the GAB and GDW models. Thermal modification and size of wood dust particles had no influence on binding energy of water molecules being linked to the secondary sorption sites. Water diffusivity decreased significantly with increasing moisture content, but only for monolayer sorption. For higher moisture content values, water diffusivity was practically independent of moisture content. These results were found for untreated and thermally modified material as well as for both dust size fractions. The influence of thermal modification on water diffusivity was unclear, which is attributed to the diffusion model, which represents dust particles as spheres and assumes instant hygroscopic equilibrium. Overall, this study indicates that the effectiveness of filtration processes likely depends strongly on sorption and diffusion properties of wood dust only at low moisture contents within the hygroscopic range.

Highlights

Wood dust formed during abrasive sanding and by other means was recognized as a carcinogenic agent as early as 1994 (e.g., Meng et al 2020)
The discreet values of Equilibrium moisture content (EMC) were acquired after approaching the hygroscopic equilibria for prescribed relative humidity (RH) levels at 25 °C
The EMC was influenced by particle size; higher EMC values were obtained for smaller particles of the same material, for both untreated and thermally modified wood dust

Summary

Introduction

Wood dust formed during abrasive sanding and by other means was recognized as a carcinogenic agent as early as 1994 (e.g., Meng et al 2020). Wood dust particles, which are spread around workplaces, can cause numerous other diseases (e.g., Jacobsen et al 2010). Exhaust system components are located outside buildings to reduce the risk of fire Under these conditions, dynamic interactions of wood dust with moist air cause water gain by wood dust when air cools as it is expelled to baghouse dust collectors. Dynamic interactions of wood dust with moist air cause water gain by wood dust when air cools as it is expelled to baghouse dust collectors Under these circumstances, the effectiveness of filtration systems is often reduced by dust cake formation

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