Wood pulp based filters for removal of sub-micrometer aerosol particles

This paper describes a method for producing air filters from wood pulp to capture sub-micrometer aerosol particles. The filters were produced from softwood and hardwood kraft pulp by wet beating to attain high surface fibrillation and subsequent partial freeze drying to retain surface fibrillation into the dry state. Filters produced by this method were evaluated for efficiency as a function of particle size, as well as pressure drop, at the upper and middle range of face velocity for respirator filters (12 and 6 cm/s). It was found that pressure losses and capture efficiencies of nebulized NaCl particles were close to those typical of N95 commercial respirator filters. In addition to these promising filtration characteristics, the wood-pulp filters offer advantages in being produced from a renewable resource and in disposability by incineration as a carbon-neutral fuel.