Toxic hazard of leachates from furfurylated wood: comparison between two different aquatic organisms.

Environmental concern regarding the use of toxic preservatives such as chromated copper arsenate (CCA) has been put forward. In the European Union, United States, and Japan, CCA has been phased out for residential and water-contact applications. Ecotoxicological studies of wood treated with conventional preservatives were carried out in the late 1990s, and it was concluded that the main impact is to water and aquatic organisms. Today, alternatives to conventional preservation methods, marketed as "environmentally friendly" or "nontoxic," are emerging. Examples of such alternatives are modified wood, e.g., thermally modified, furfurylated, and acetylated wood. To date, not enough hazard characterization has been performed. In the present study, the Microtox assay with the marine bacterium Vibrio fischeri and the Daphtox procedure with the crustacean Daphnia magna were used as screening methods in an effect assessment. Both organisms were exposed to water leachates from furfurylated wood using two different leaching procedures. The results indicate that Microtox is more sensitive to the toxic components from furfurylated wood than Daphtox. Furthermore, the toxicity of treated Pinus radiata was higher than that of treated Pinus sylvestris. The toxicity did not diminish over the test period, as is the case for preservative-treated wood. The present study found that treatment conditions can influence the toxicity considerably, so toxicity studies should be included in the development of new treatment process. The present study also shows that using an intermediate vacuum-drying step, leading to a more efficient curing/polymerization, results in slightly less hydrophobic oligomers in the product, such that the leachates become less toxic to bacteria.

Structural characterization and mechanical properties of wet-processed fibreboard based on chemo-thermomechanical pulp, furanic resin and cellulose nanocrystals.

Fibreboards are made of lignocellulosic fibres and synthetic adhesive which connect them. These synthetic adhesives, while relatively low-cost, are usually non-biodegradable and may cause health and environmental issues. Therefore, in recent years, there has been an increased demand for replacing these adhesives with bio-derived adhesives. The present study aims to develop fibreboards from chemo-thermomechanical pulp (CTMP) and a furanic resin based on prepolymers of furfuryl alcohol via wet-processing. To improve the bonding properties, maleic acid, aluminium sulphate, and cellulose nanocrystals (CNCs) were added. The resulting fibreboards were evaluated for their structural features and mechanical properties. The bending strength was improved when CNCs were added into the fibre's suspension, and the morphology indicated a more compact structure. The combination of the CTMP with CNC and Biorez resulted in the same mechanical behaviours as those noted for CTMP alone, the best performance being observed for the boards in which Al2(SO4)3 was added. Infrared spectroscopy and X-ray diffraction also proved the presence of cellulose nanocrystals and resin in the boards by increased specific bands intensity and crystallinity index, respectively.

Toxic hazard and chemical analysis of leachates from furfurylated wood.

The furfurylation process is an extensively investigated wood modification process. Furfuryl alcohol molecules penetrate into the wood cell wall and polymerize in situ. This results in a permanent swelling of the wood cell walls. It is unclear whether or not chemical bonds exist between the furfuryl alcohol polymer and the wood. In the present study, five different wood species were used, both hardwoods and softwoods. They were treated with three different furfurylation procedures and leached according to three different leaching methods. The present study shows that, in general, the leachates from furfurylated wood have low toxicity. It also shows that the choice of leaching method is decisive for the outcome of the toxicity results. Earlier studies have shown that leachates from wood treated with furfuryl alcohol prepolymers have higher toxicity to Vibrio fischeri than leachates from wood treated with furfuryl alcohol monomers. This is probably attributable to differences in leaching of chemical compounds. The present study shows that this difference in the toxicity most likely cannot be attributed to maleic acid, furan, furfural, furfuryl alcohol, or 2-furoic acid. However, the difference might be caused by the two substances 5-hydroxymethylfurfural and 2,5-furandimethanol. The present study found no difference in the amount of leached furfuryl alcohol between leachates from furfurylated softwood and furfurylated hardwood species. Earlier studies have indicated differences in grafting of furfuryl alcohol to lignin. However, nothing was found in the present study that could support this. The leachates of furfurylated wood still need to be