Influence of exposure time, wood species and dimension on the remaining copper and chromium content in CC-treated wood after field and laboratory leaching tests

Abstract

Most studies on preservative depletion from treated wood are performed with small samples on a laboratory scale. Although these studies provided repeatable and constant test parameters, the results have little applicability to real conditions. Therefore, a series of laboratory tests were carried out according to CEN/TS 15119 part 1 and part 2 by means of EN 252 and non-standard sized Scots pine sapwood as well as spruce stakes. The stakes were impregnated by vacuum pressure with chromium (Cr)-copper(Cu)-containing wood preservative. For comparison, a set of 18 stakes per test parameter was installed at a test site (in ground use), whereby, every 4 months, three stakes from each series were removed for analysis. Both the time depending losses of metal as well as the remaining element contents were determined for samples exposed under lab conditions, whereas distribution and remaining element contents were measured for samples exposed in the field. The obtained data were evaluated regarding factors influencing the metal leaching, such as exposure time, wood species, or dimension. The results showed that wood species had a significant effect on the Cu depletion, while it had less influence on the Cr loss. Cr and Cu distribution in the standard and non-standard sized pine sapwood significantly changed as compared to spruce. In addition, comparison of the laboratory and field test results indicated that metal depletion is greater in field exposure compared to both laboratory tests.

Influence of wood sample size and species on the leaching of chromium and copper using different lab tests

“…It is known that during fixation reactions with wood, chromium reacts strongly with lignin (Eadi and Wallace 1962) while copper binds to with cellulose materials (Flomina 1967). The low amount of chromium depletion was also observed in numerous laboratory and field studies (Archer et al 1994, Evans et al 1994, Lebow 1996, Cooper and Ung 1997, Melcher and Wegen 2000, Garcia-Valcarcel et al 2004, Lebow 2014, Temiz et al 2014, Bahmani et al 2015a, Bahmani et al 2015b. Higher loss of copper might be explained by the fact that pine sapwood is better penetrated by the negative charged chromates than by the positive copper ions as was shown by Jüngel et al (1998).…”

Influence of Copper and Biopolymer/Saqez Resin on the Properties of Poplar Wood

“…Predominant hygroscopicity, resulting from the presence of the abundant hydroxyl groups in wood, renders it susceptible to fungal infestation. Wood and wood-based products often need treatments with preservatives to increase durability and achieve the desired service life [3][4][5][6]. One effective method to improve the bio-resistance features of wood and wood-based products is the utilization of natural substances, such as plant essential oils and resins [7,8].…”