Influence of Biomass Combustion Products on Element Content and Thermal Stability of Latvian Sheep Breed Wool Filter Fibres

Abstract

Sheep wool is natural, easy obtainable, renewable and biodegradable material with a perspective application as a sorbent in filters for purification of industrial emissions from various environmental pollutants. The element content and thermal stability of Latvian dark-headed sheep wool filter fibres was analysed and described before and after exposure to biomass combustion products. Based on the obtained results, it is concluded that the sheep wool filter fibres can sorb various gaseous combustion products, such as carbon monoxide (CO), carbon dioxide (CO₂) and nitrogen oxides (NO_x), however, the sorption processes of these gases are irreversible. The obtained results of total reflection X-ray fluorescence and inductively coupled plasma mass spectrometry suggest that the concentration of heavy metals, such as lead, zinc and iron, significantly increases in the sheep wool filter fibres after exposure to biomass combustion products. In thermogravimetric curves, no significant changes were detected for the sheep wool filter fibres after exposure to combustion products, while in differently thermal analysis curves, the formation of exothermic peak at around 580 °C was observed and could be related to autoignition. Using X-ray diffractometry and scanning electron microscopy coupled with energy dispersive X-ray spectrometry, the solid particles of biomass combustion products were observed on the scaly surface of the sheep wool filter fibres, and these particles mainly consist of potassium chloride, carbon, sulphur and various metal oxides.