Radiata Pine Wood Treated with Copper Nanoparticles: Leaching Analysis and Fungal Degradation

Abstract

Radiata pine is the main wood species used in the Chilean construction industry, but it must be protected due to its low natural durability. Chemical protection of wood by impregnation allows for a more efficient utilization of the forest resources by extending its useful life. The use of nanoparticles in wood protection has garnered great interest during the last decade, due to their unique physicochemical properties, different from those of larger sized materials. In this research, the impregnation of radiata pine wood with copper nanoparticles (CuNP) was studied in terms of retention, penetration, leaching, and its protective effect against wood rot fungi growth according to EN 113, AWPA A3-91, A9-18, and E11-16. Penetration analysis confirmed a uniform distribution across the wood, with total penetration in the impregnated samples with the highest concentration solution of CuNP. Retention values of the impregnated wood increased proportionally with the concentration of nanoparticles evaluated by EDXRF. Leaching analysis showed copper removal during the first hours of the test, with a constant leaching rate up to 144 h. Impregnated wood mass loss (ML) due to exposure to Gloeophyllum trabeum and Rhodonia placenta fungi were significantly reduced regardless of the CuNP concentration or fungi tested, with an ML smaller than 5% and smaller than 14% for leached samples.

Analyses of Impregnation Quality and Mechanical Properties of Radiata Pine Wood Treated with Copper Nanoparticle- and Micronized-Copper-Based Wood Preservatives

“…Copper nanoparticle (CuNP) solutions were provided by NanoProcess SpA company (Antofagasta, Chile). Some of the CuNP's characteristics in solution used in this study were reported in a previous work, such as the average NP size of 24 nm, polydispersity index of 0.375 and Z-potential of −15.0 mV [2].…”

“…However, it should be noted that the risk levels are associated with use of wood (outdoor or indoor use) and the fungicidal and insecticidal effectiveness of preserved wood. Studies of fungal resistance of wood impregnated with CuNP have been reported, where the CuNP effectiveness against certain fungi has been confirmed [2,7,14,15,19]. Recently, Aguayo et al [2] reported that radiata pine wood impregnated with CuNP is effective against brown rot fungi.…”

“…Studies of fungal resistance of wood impregnated with CuNP have been reported, where the CuNP effectiveness against certain fungi has been confirmed [2,7,14,15,19]. Recently, Aguayo et al [2] reported that radiata pine wood impregnated with CuNP is effective against brown rot fungi. For ED XRF retention values between 0.64 kg/m 3 and 1.68 kg/m 3 , the mass loss in the samples inoculated with Gloeophyllum trabeum and Rhodonia placenta was less than 5%.…”

“…Wood occupies a prominent place as a building material due to its attractive properties such as mechanical strength and low thermal expansion compared to other building materials [1]. Most wood species commonly used in construction deteriorate if exposed to conditions that support the growth of wood degrading organisms [2]. This deterioration drastically decreases the strength properties of wood and creates a challenge in controlling and analyzing various factors, including the physical-chemical factors that have a potential impact on the useful life of wood [3].…”

“…The microdistribution of preservatives containing nanoparticles in wood is different from those of common water-borne preservatives because most of these particles are too large to penetrate the microporosity of the cell wall [14]. The use of nanoparticles in wood preservation has been evaluated in different research works, mainly focusing on the fungal degradation, leaching of bioactive compounds [2,7,[15][16][17] and the performance of wood treated with metal nanoparticles in termite bioassays [18,19]. However, there is scarce information about the mechanical properties of nanoparticlestreated wood, being that the physic-mechanical properties of wood provide important information for its classification, as well as quality indicators for its use in construction [20].…”