Influence of prolonged exposure of wood to water on wood structure and biochar properties

The structural changes of birch and pinewood under the influence of prolonged exposure to water were studied. It has been shown that prolonged aqueous treatment of birch increases the degree of crystallinity of cellulose. On the contrary, similar treatment of pinewood leads to its decrease. The specific role of hydroxyl groups of cellulose in the interaction of wood with water has been revealed. It has been noted that the O/H ratio for wood correlates to the hydrophilicity and crystallinity of cellulose. The possibility of producing porous products from different species of wood after prolonged soaking in water has been shown. The carbonization of the samples up to 800 °C leads to significant growth of the specific surface area of carbon product from 10–20 to 200–400 m2/g. It is assumed that a soft change of wood structure under the influence of water leads to the formation of weakly bound low molecular weight fragments, which are converted into volatile products for carbonization, and the formation of porous carbon product.