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Fixation, leachability, and decay resistance of wood treated with some commercial extracts and wood preservative salts
International Biodeterioration & Biodegradation 63 (2009) 135–141
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Fixation, leachability, and decay resistance of wood treated with some commercial extracts and wood preservative salts Selim Sen*, Cihat Tascioglu, Kamile Tırak ¨ zce University, Forestry Faculty, 81620 Du ¨ zce, Turkey Du
a r t i c l e i n f o
a b s t r a c t
Article history: Received 11 April 2007 Received in revised form 25 July 2008 Accepted 26 July 2008 Available online 23 September 2008
Beech (Fagus orientalis) and Scots pine (Pinus sylvestris) wood blocks were treated with some commercial extracts as well as water-based wood preservative salts at various concentrations to increase retention and fixation. The penetration, fixation, and antifungal properties of different treatment solutions were compared with statistical analysis. Retention levels of solutions were generally higher for Scots pine wood than beech wood. The highest retention levels were seen in wood treated with sumac leaf extract and oak valonia extract. Leaching tests indicated that both wood types treated with sumac extracts showed higher retention levels than wood treated with the other fruit and bark extract solutions. Adding 1% water-based wood preservative salts to valonia and sumac leaf extracts increased the retention levels. Concentrations of more than 1% did not contribute to retention either individually or with salt additions. Three percent and higher concentrations of wood-preserving salts accelerated and increased the amount of leaching. The results showed that the extract alone was resistant to leaching. Mycological tests showed that all extractives were significantly effective against wood decay. Ó 2008 Elsevier Ltd. All rights reserved.
Keywords: Plant extracts Antifungal Wood treatment Retention Fixation
1. Introduction Human health and environmental concerns have restricted the use of traditional wood preservatives; therefore, much effort has concentrated on finding nontoxic and eco-friendly alternatives (S¸en, 2001; S¸en et al., 2002a). For example, ongoing studies are investigating the use of tannins for nontoxic wood preservatives. The word ‘‘tannin’’ has been used loosely to define two different classes of chemical compounds of mainly phenolic nature: hydrolysable and condensed tannins (Pizzi, 1998). Tannins occur naturally in the bark, fruit, and leaves of plants at various concentrations (Hus¸, 1969). Herbal extracts that have antifungal and insecticide properties (Dıg˘rak et al., 1998; Dıg˘rak et al., 2001) present fixation problems for treated wood. Some methods have proven effective for decreasing the extent of tannin leaching from treated wood (Thevenon et al., 1997; Pizzi and Baecker, 1996). When treating porous wood, the most important property is the preservative viscosity. Reduced viscosity increases liquid retention and therefore the penetration of the treatment solution. However, porous wood acts as a filter by preventing the absorption of large, low-density molecules, which can nullify the effect of increased viscosity (Nicholas, 1973).
* Corresponding author. Tel.: þ903805421137 (3301); þ905057512213 (mobile); fax: þ903805421136. E-mail address: [email protected] (S. Sen). 0964-8305/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.ibiod.2008.07.007
Wood is a porous material and in many respects acts like a filter to liquids flowing through it. Due to the extremely small pore size, in most cases wood can be regarded as an ultra-filter. Thus, it is predicted that wood treatment solutions that contain particulate matter will plug the pores during the impregnation process (Nicholas, 1973). For this reason, it is difficult for the extractives to penetrate into the wood structure (Tırak, 2006). Commercial extracts from valonia oak, sumac leaves, and gallnut powder have been used as raw materials in the Turkish leather industry for many years because of their rich tannin content. Dıg˘rak et al. (1998, 2001) found that some commercial extracts used in the leather industry have positive antimicrobial, antifungal, and insecticidal activities. S¸en (2001) conducted field and laboratory tests of the effectiveness of valonia oak, gallnut powder, and Pinus brutia bark extracts in 1%, 3%, 5%, 7%, and 10% solutions as antifungal agents on spruce, fir, beech, and alder wood blocks. He found that these plant extracts have high antifungal activity, but showed poor fixation in outdoor and laboratory tests. However, concentrations of 4% of commercial plant extracts showed antifungal activity against white-rot (Pleurotus ostreatus) and brown-rot fungi (Phanerochaete chrysosporium) (S¸en et al., 2002a). In addition, extracts at concentrations of 4% showed insecticidal activity against larvae of Rhagium inquisitor (S¸en et al., 2002b). In this study, we investigated plant extracts from leaves of Sicilian sumac (Rhus coriaria L.), valonia oak (Quercus macrolepis KyQ.aegilops L.), and bark of Turkish pine (Pinus brutia Ten.), which
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Table 1 Extract solutions and their pH used in the treatments Valex solutions
pH
Sumex solutions
pH
Pinex solutions
pH
4% 4% 1% 3% 1% 3% 1% 3% 1% 3% 1% 1% 1% 1%
3.75
4% 4% 1% 3% 1% 3% 1% 3% 1% 3% 1% 1% 1% 1%
4.26
4% 4% 1% 3% 1% 3% 1% 3% 1% 3% 1% 1% 1% 1%
3.48
Valex Valex þ Boric acid Boric acid Borax Borax Al2(SO4)3 Al2(SO4)3 CuSO4 CuSO4 Ba þ 1% Bx Ba þ 1% Al2(SO4)3 Bx þ 1% Al2(SO4)3 Ba þ 1% CuSO4
3.14 2.63 5.09 7.28 2.27 2.14 2.58 2.28 4.41 2.61 3.22 2.74
Sumex Sumex þ Boric acid Boric acid Borax Borax Al2(SO4)3 Al2(SO4)3 CuSO4 CuSO4 Ba þ 1% Bx Ba þ 1% Al2(SO4)3 Bx þ 1% Al2(SO4)3 Ba þ 1% CuSO4
4.00 3.76 5.80 7.83 3.13 2.95 3.41 3.12 5.06 2.97 3.52 3.26
Pinex Pinex þ Boric acid Boric acid Borax Borax Al2(SO4)3 Al2(SO4)3 CuSO4 CuSO4 Ba þ 1% Bx Ba þ 1% Al2(SO4)3 Bx þ 1% Al2(SO4)3 Ba þ 1% CuSO4
3.40 3.28 8.30 8.96 3.08 3.11 2.87 2.92 7.46 3.10 4.30 3.02
Al2(SO4)3 – aluminum Sulfate; CuSO4 – copper sulfate.
have been used in the Turkish leather industry for centuries. These plants are abundant, natural sources of tannins. To improve the wood protection effectiveness of extracts, they should be absorbed well into the material, and this process is defined as fixation. Here we investigated the retention, fixation, and fungal resistance of Scots pine and beech wood treated with plant extracts and a combination of boric acid, borax, aluminum sulfate, and copper sulfate. We also attempted to improve the fixation ability of plant extracts using water-based wood preservatives.
solution from the wood surface, and weighed (to the nearest 0.01 g) to determine the retention of each solution. Retention was calculated using the following formula: R ¼
GC 10 kg=m3 V
R ¼
GC ðg; based on oven dry weightÞ 100
2.1. Preparation of test specimens
After calculating retention, samples were weighed and then dried at 103 C.
Table 3 Retention levels of S. pine and Beech wood samples treated with solutions Solutions and concentrations
1
%4 Extract
We used the classic reverse current method to produce the valonia extract (valex), sumac leaf extract (sumex), and pine bark extract (pinex) from Turkey (Tırak, 2006). Bark, leaves, and fruit were broken into small pieces using a grinder. The pieces were then extracted in hot water at 85 5 C for 2 h. Density was determined using a hydrometer, and the extract solution was prepared at 4% concentration. The solution types used were as follows: 4% extract, 4% extract þ 1% salt, 4% extract þ 3% salt, and 4% extract þ 1% salt 1 þ1% salt 2. The names and concentrations of the extracts and salts are provided in Table 1.
2
%4
3
%4
4
%4
5
%4
6
%4
7
%4
8
%4
9
%4
Wood samples were treated using a full-cell pressure process at 1 bar vacuum (30 min) with 8 bar pressure (60 min), followed by 15 min at atmospheric pressure. Treated blocks were air-dried for 7 days to ensure fixation of the chemicals within the test specimens. Untreated blocks were used as controls. Following impregnation, wood samples were removed from the treatment solution, wiped lightly to remove
10 %4 Table 2 Evaluation system for measuring the extent of fungal attacks (TS ENV 839/2006) Value State and appearance 0 1 2
No visible fungal attack or decay Mycelium penetrates into the cross-section of the wood sample Mycelium penetrates 1/5th of the way through the cross-section of wood sample
Wood Retentions samples (kg/m3)
(%)
Valex Sumex Pinex Valex Sumex Pinex
2.2. Preparation of treatment solutions
2.3. Treatment method
T2 T1 100ð%Þ T1
G ¼ (T2 T1): Grams of treatment solution absorbed by the block (initial weight of block subtracted from the initial weight plus the treatment solution absorbed) C: Grams of preservative solutions in 100 g of the treatment solution V: Volume of block in cubic centimeters T2: Sample of weight after treatment T1: Sample of weight before treatment.
2. Materials and methods
Scots pine (Pinus sylvestris) and beech (Fagus orientalis) wood specimens were cut into 50 20 15-mm blocks. All specimens were oven-dried at 103 2 C for 48 h before and after treatment. The plant extracts were obtained from a variety of regions in Anatolia. Valex was obtained from valonia oak (Quercus macrolepis Ky.) produced at the Salihli AR-TU Chemistry Plant. Brutia pine bark powder was obtained from Pinus brutia grown in the Mersin region, and sumac leaf powder was obtained from Rhus coriariae grown in Kahramanmaras. Solutions containing 1% and 3% boric acid (Ba), borax (Bx), aluminum sulfate [Al2(SO4)3], or copper sulfate (CuSO4), and 4% plant extract solutions were prepared. These salt solutions and single extracts were then infiltrated into beech (Fagus orientalis) and Scots pine (P. sylvestris) wood blocks. The tannin contents of the plant extracts used in this study were 34% (cortex Pinus brutia bark), 64% (sumac leaf powder), and 68% (valonia oak powder) (Tırak, 2006).
R ¼
11 %4 12 %4 13 %4
Pine Beech Extract þ %1Ba Pine Beech Extract þ %1 Bx Pine Beech Extract þ %1 AlS Pine Beech Extract þ 1CuS Pine Beech Ext þ %3 Ba Pine Beech Extract þ %3 Bx Pine Beech Extract þ %3 AlS Pine Beech Extract þ %3 CuS Pine Beech Ext þ %1 Ba þ %1 Bx Pine Beech Ext þ %1 Ba þ %1 AlS Pine Beech Ext þ %1 Bx þ %1 AlS Pine Beech Ext þ %1 Ba þ %1 CuS Pine Beech
25 21 46 37 52 40 33 32 36 31 28 28 28 25 19 21 19 19 31 28 26 31 22 23 21 34
40 33 52 46 63 43 29 34 30 25 30 27 30 23 24 29 27 23 29 22 27 28 24 25 22 30
41 13 15 21 11 19 41 27 14 13 18 15 20 13 21 16 19 9 23 21 17 19 16 17 15 21
145 79 238 123 274 134 163 101 183 103 104 63 100 53 68 48 66 40 131 67 112 79 97 60 101 71
240 126 269 150 327 140 140 103 151 85 109 59 109 47 87 64 92 46 120 50 113 69 103 64 105 64
233 45 78 70 58 58 204 87 71 44 65 33 73 26 76 37 64 20 96 48 70 48 68 45 70 45
Ba – boric acid Bx – borax; AlS – aluminum sulfate Al2(SO4)3; CuS – copper sulfate CuSO4.
S. Sen et al. / International Biodeterioration & Biodegradation 63 (2009) 135–141
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Table 4 ANOVA showing retention and fixation values for Scots pine and beech wood samples after treatment with extracts alone and with salts (based on oven dry weight, g) Solutions and concentrations
Sum of squares
Degree of free
Mean square
F
Sig
0.004 0.017 0.002 0.004 0.007 0.021 0.004 0.003 0.009 0.006 0.005 0.008 0.006
39.32 8.163 27.29 9.707 25.84 25.37 3.829 6.680 29.99 68.85 1.445 1.942 29.01
0.000 0.000 0.000 0.000 0.000 0.000 0.020 0.002 0.000 0.000 0.251 0.146 0.000
0.183 0.031 0.030 0.046 0.072 0.161 0.017 0.023 0.100 0.061 0.017 0.008 0.037
0.003 0.001 0.001 0.002 0.001 0.006 0.001 0.002 0.003 0.010 0.002 0.001 0.004
72.89 37.67 31.21 20.23 53.67 26.79 15.58 15.09 34.47 6.019 7.262 7.941 8.582
0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.003 0.001 0.001 0.000
11 15 15 15 47 15 15 15 47 15 15 15 47
0.010 0.012 0.000 0.002 0.006 0.002 0.008 0.010 0.006 0.000 0.012 0.008 0.008
0.000 0.001 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000
19.87 21.61 1.111 5.026 19.09 13.10 25.00 69.94 27.86 – 38.27 44.95 53.42
0.000 0.000 0.383 0.017 0.000 0.000 0.000 0.000 0.000 – 0.000 0.000 0.000
11 15 15 15 47 15 15 15 47 15 15 15 47
0.006 0.005 0.000 0.006 0.005 0.000 0.008 0.001 0.003 0.000 0.001 0.006 0.002
0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000
16.93 32.83 0.231 25.55 35.84 2.800 79.84 12.61 23.94 1.571 18.77 68.27 47.35
0.001 0.000 0.873 0.000 0.000 0.085 0.000 0.001 0.000 0.248 0.000 0.000 0.000
BG
WG
Total
BG
WG
Total
BG
WG
0.305 0.413 0.132 0.105 2.106 1.565 0.041 0.053 3.092 1.197 0.021 0.049 2.237
0.082 0.472 0.045 0.101 0.618 0.576 0.099 0.074 0.782 0.162 0.139 0.236 0.585
0.387 0.884 0.177 0.206 2.725 2.140 0.140 0.127 3.874 1.359 0.160 0.285 2.822
2 3 3 3 12 3 3 3 12 3 3 3 12
21 28 28 28 91 28 28 28 91 28 28 28 91
23 31 31 31 103 31 31 31 103 31 31 31 103
0.153 0.138 0.044 0.035 0.176 0.522 0.014 0.018 0.258 0.399 0.007 0.016 0.186
0.367 0.093 0.089 0.137 0.865 0.483 0.050 0.068 1.197 0.183 0.051 0.023 0.450
0.053 0.023 0.027 0.063 0.122 0.168 0.030 0.042 0.263 0.284 0.065 0.027 0.398
0.419 0.116 0.116 0.201 0.987 0.651 0.080 0.110 1.460 0.467 0.116 0.051 0.847
2 3 3 3 12 3 3 3 12 3 3 3 12
21 28 28 28 91 28 28 28 91 28 28 28 91
23 31 31 31 103 31 31 31 103 31 31 31 103
0.019 0.036 0.000 0.005 0.064 0.006 0.025 0.029 0.065 0.000 0.035 0.023 0.093
0.004 0.007 0.000 0.004 0.011 0.002 0.004 0.002 0.008 0.000 0.004 0.002 0.006
0.024 0.043 0.001 0.009 0.075 0.008 0.029 0.031 0.073 0.000 0.039 0.025 0.099
2 3 3 3 11 3 3 3 11 3 3 3 11
9 12 12 12 36 12 12 12 36 12 12 12 36
0.012 0.015 0.000 0.017 0.052 0.001 0.025 0.004 0.032 0.000 0.003 0.018 0.027
0.003 0.002 0.000 0.003 0.005 0.002 0.001 0.001 0.004 0.000 0.001 0.001 0.002
0.015 0.016 0.000 0.020 0.057 0.003 0.026 0.005 0.037 0.000 0.004 0.019 0.029
2 3 3 3 11 3 3 3 11 3 3 3 11
9 12 12 12 36 12 12 12 36 12 12 12 36
Retentions Scots pine wood samples Extracts Pinex 1% salt addition 3% salt addition 1% þ 1% salt add All valex solut. Sumex 1% salt addition 3% salt addition 1% þ 1% salt add All sumex solut. Valex 1% salt addition 3% salt addition 1% þ 1% salt add All pinex solut. Beech wood samples Extracts Pinex 1% salt addition 3% salt addition 1% þ 1% salt add All valex solut. Sumex 1% salt addition 3% salt addition 1% þ 1% salt add All sumex solut. Valex 1% salt addition 3% salt addition 1% þ 1% salt add All pinex solut. Fixation Scots pine wood samples Extracts Pinex 1% salt addition 3% salt addition 1% þ 1% salt add All valex solut. Sumex 1% salt addition 3% salt addition 1% þ 1% salt add All sumex solut. Valex 1% salt addition 3% salt addition 1% þ 1% salt add All pinex solut. Beech wood samples Extracts Pinex 1% salt addition 3% salt addition 1% þ 1% salt add All valex solut. Sumex 1% salt addition 3% salt addition 1% þ 1% salt add All sumex solut. Valex 1% salt addition 3% salt addition 1% þ %1 salt add All of pinex sol. BG: between groups, WG: within groups. 2.4. Leaching test The leaching test was conducted on four samples of eight impregnated and four samples of eight untreated control wood blocks. Leaching samples were placed into 600 ml of distilled water for 24 h. This procedure was then repeated with fresh water for 14 days. The leached samples were collected after water replacement and dried at 103 C for 48 h (AWPA Standards, E11-97, 1999). All leached and unleached samples were exposed to fungal test.
fungi, Trametes versicolor (Mad-697), and Scots pine samples were exposed to brown-rot fungi, Gloeophyllum trabeum (Mad-617-R), according to TS 5563 EN 113/1996. All specimens were incubated for 12 weeks at 25 C and then brushed and dried at 103 C. Evaluation of fungal performance was carried out by visual inspection. Mycelium penetration depth was measured using a compass according to TS ENV 839/2006. Table 2 shows the evaluation standards used for measuring the extent of decay caused by fungal attack.
2.5. Wood-decay test
2.6. Statistical analysis
Four unleached and four leached treated specimens and their respective untreated controls were exposed to fungal attack after leached tests. Beech wood was exposed in petri dishes containing agar medium inoculated with white-rot
Retention and leaching and weight loss values were evaluated using a computerized SPSS 13.0 statistical program and tested with Univarite, followed by a Duncan test with a 95% confidence interval.
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S. Sen et al. / International Biodeterioration & Biodegradation 63 (2009) 135–141 Table 6 Duncan test results of the groups concerned with retentions and fixations
Fig. 1. The average retentions of extractives in Scots pine and Beech wood samples.
3. Results 3.1. Retention results Retention levels of treated Scots pine and Beech wood are shown in Table 3 as kilograms per cubic meter and percentages. The highest retention of the solutions was observed in the Scots pine wood samples. The retention rate of plant extract solutions was the highest in sumac leaves (Sumex) and valonia oak (Valex). Pinus brutia bark extract (Pinex) had the lowest retention. When the extracts were used alone (i.e., without salts), retention increased to 66% for Valex, 114% for Sumex, and 188% for Pinex. A 1% Ba or 1% Bx plus Valex or Sumex extract further increased the retention. However, Ba and Bo had a negative effect with Pinex extract. With aluminum sulfate and Valex, the increase in retention was limited, and there was a decrease in wood treated with Sumex and aluminum sulfate. The highest retention increase was obtained with Pinex and 1% aluminum sulfate. Other mineral salts gave different retention increases of between 20 and 80%. In general, 1%
Factor
Treatment
Retentions
Groups
Fixations
Species
Scotch pine Beech
0.408 0.376
a* b
– –
Solution groups
Valex Sumex Pinex
0.436 0.467 0.272
b a c
0.0324 0.0428 0.0316
a b a
Solutions
%4 %4 %4 %4 %4 %4 %4 %4 %4 %4 %4 %4 %4
0.428 0.535 0.561 0.488 0.362 0.372 0.351 0.316 0.291 0.371 0.357 0.308 0.354
c a a b d d d e e d d e d
0.1338 0.0192 0.0188 0.0508 0.0146 0.0492 0.0079 0.0300 0.0038 0.0458 0.0608 0.0258 0.0025
k e e h d h c g c h i f c
Ext Ext þ %1 Ext þ %1 Ext þ %1 Ext þ %1 Ext þ %3 Ext þ %3 Ext þ %3 Ext þ %3 Ext þ %1 Ext þ %1 Ext þ %1 Ext þ %1
Ba Bx Al. Sulp. Cu. Sulp. Ba Bx Al. Sulp. Cu. Sulp. Ba þ %1 Bx Ba þ %1 AlS Bx þ %1 AlS Ba þ %1 CuS
Groups
‘*’ means within each factor and column followed same letter are not significantly different (a ¼ 0.05). Based on oven dry weight.
Bo, 1% Ba, 1% Al2(SO4)3, or 1% CuSO4 added to Valex and Sumex (but not Pinex) extract had a positive effect on retention. A one-way ANOVA for retention and fixation in Scots pine and beech wood samples is shown in Table 4. The results show that retention did not vary significantly in Sumex and Pinex solutions with added 3% Ba, 3% Bx, 3% Al2(SO4)3, or 3% CuSO4 in Scots pine wood. However, differences in fixation were not significant between the solution groups containing 1% or 3% salts in Scots pine wood. In addition, there were no significant differences in fixation between Valex solutions with 3% added salts, Sumex solution with 1% added salts, and Pinex solutions with 1% added salts in beech wood samples. The results of fixation and retention in other solutions with added salts were significant. The average retention results are shown in Fig. 1. Higher retention was found for Valex and Sumex solutions in Scots pine and beech wood blocks. All three extracts also had higher retention in Scots pine. Two-way and three-way interactions for retention and fixation in terms of tree species, extract, and treatment solutions were
Table 5 Analyses of variances (ANOVA) for the effects of tree species, extractive species and preservative solutions on variables (retention, fixation) (p < 0.001) Variable
Source
Retention
Tree species Extractives Solutions Tree species þ extractives Tree species þ solutions Extractives þ solutions Tree species þ extractives þ solutions
Mean square
F
Sign
0.166 4.533 4.241 0.022 0.976 3.558 1.113
1 2 12 2 12 24 24
0.166 2.266 0.353 0.011 0.081 0.148 0.046
32.662 446.151 69.578 2.144 16.010 29.185 9.131
0.000 0.000 0.000 0.118 0.000 0.000 0.000
2.763 17.396
544 621
0.005 –
– –
– –
Tree species Extractives Solutions Tree species þ extractives Tree species þ solutions Extractives þ solutions Tree spec. þ extracts þ solutions
0.011 0.008 0.355 0.006 0.064 0.169 0.033
1 2 12 2 12 24 24
0.011 0.004 0.030 0.003 0.005 0.007 0.001
61.170 22.027 161.437 16.821 29.136 38.385 7.585
0.000 0.000 0.000 0.000 0.000 0.000 0.000
Error Corrected total
0.043 0.689
234 311
0.000 –
– –
– –
Error Corrected total Fixation
Dependent variable: based on oven dry weight.
Sum of squares
Degree of free
S. Sen et al. / International Biodeterioration & Biodegradation 63 (2009) 135–141
139
Table 8 Weight losses (%) due to fungus-induced decay No. Solutions
Valex S. Pine L
1 2 3 4 5 6 7 8 9 10 11 12 13
%4 Extractive %4 Extractive þ %1 Ba %4 Extractive þ %1 Bx %4 Extractive þ %1 Al. Sulp. %4 Extractive þ %1 Cu. Sulp. %4 Extractive þ %3 Ba %4 Extractive þ %3 Bx %4 Extractive þ %3 Al. Sulp. %4 Extractive þ %3 Cu. Sulp. %4 Extractive þ %1 Ba þ %1 Bx %4 Extractive þ %1 Ba þ %1 Al. Sulp. %4 Extractive þ %1 Bx þ %1 Al. Sulp. %4 Extractive þ %1 Ba þ %1 Cu. Sulp. Control samples (no treatment)
Sumex
Pinex
Beech S.Pine Beech S. Pine
U L
U L
U L
16 5 31 4 18 6 11 4 16 2 15 8 9 3 18 3 10 6 11 6 24 7 31 8 36 2 7 2 28 3 14 12 15 13 12 2 15 4 17 3 9 4 25 2 16 14 18 2 27 1 34 1 25 0 18 4 16 3 17 2 34 3 15 3 13 8 23 4 18 2 18 6 35 1 26 2 34 1 37 31 38 32 33 25
29 14 16 26 29 15 16 15 25 15 16 15 36 32
Beech
U L
U L
13 7 9 14 1 3 4 13 0 3 8 2 0 32
11 8 9 10 4 6 9 17 1 8 12 4 1 21
23 36 13 21 18 27 19 26 16 16 18 29 35 27
U
25 8 16 5 15 8 16 6 29 2 13 5 20 3 15 2 27 0 13 3 33 1 14 3 34 1 29 24
L: leached; U: unleached.
Fig. 2. (a) The average retention of solutions in Scots pine and Beech wood samples; (b) the average retentions of solutions in terms of extract used.
investigated with SPSS 13.0 with univariate analysis (Table 5). We used a completely randomized design (CRD) with eight replications for retentions as net weight of salt, and four replications for fixation. The interactions of tree species, solution, and concentration with retention were significant at the 95% confidence level. Twoway interactions with tree species–concentration and solution– concentration were significant, whereas interactions between tree species and solution were not. The three-way interaction of tree species–solution–concentration was significant at the 95% confidence level. All one-way and two-way interactions were significant at the same confidence level for tree species, solutions, and concentration in the fixation tests. There was a positive effect of a concentration of 1% adding salts to plant extracts in terms of wood protection. Results of a Duncan test showed that when the salt concentration increased, protection also increased (Table 6). However, there were no significant effects of the impregnated solutions with high and low salt concentrations in leached wood samples in terms of fungal decay. Fig. 2a shows retention by tree species. Fig. 2b shows retention in terms of solutions used. The interaction results of extracts alone and together with salts show that Valex and Sumex with 1% Bo were the most effective in wood. Retention was higher in Scots pine, a softwood species, than in beech. In addition, retention increased when plant extracts were
Table 7 Evaluation of mycelium penetration in Scots pine wood inoculated with G. trabeum and in beech wood inoculated with T. versicolor. No.
Solutions
Valex
Sumex
S. Pine 1 2 3 4 5 6 7 8 9 10 11 12 13
%4 Extractive %4 Extractive þ %1 Ba %4 Extractive þ %1 Bx %4 Extractive þ %1 Al. Sulp. %4 Extractive þ %1 Cu. Sulp. %4 Extractive þ %3 Ba %4 Extractive þ %3 Bx %4 Extractive þ %3 Al. Sulp. %4 Extractive þ %3 Cu. Sulp. %4 Extractive þ %1 Ba þ %1 Bx %4 Extractive þ %1 Ba þ %1 Al. Sulp. %4 Extractive þ %1 Bx þ %1 Al. Sulp. %4 Extractive þ %1 Ba þ %1 Cu. Sulp. Control Samples (without treatment)
L: leached U: unleached.
L 2 1 1 1 2 1 1 2 2 1 2 2 2 2
Beech U 1 0 0 1 0 1 1 0 0 0 0 0 0 2
L 2 1 1 2 1 1 1 1 2 1 1 2 1 2
Pinex
S. Pine U 0 0 0 1 0 1 0 1 0 0 0 0 0 2
L 2 1 1 2 2 1 1 1 2 1 2 2 2 2
Beech U 0 0 0 1 0 0 0 0 0 0 0 1 0 2
L 2 1 1 2 2 1 1 1 2 1 1 1 2 2
S. Pine U 1 0 1 1 0 0 0 1 0 0 0 0 0 2
L 2 1 1 2 1 2 1 2 1 1 1 2 2 2
Beech U 1 0 0 1 0 0 0 1 0 0 0 0 0 2
L 2 1 1 2 2 1 1 1 2 1 2 1 2 2
U 1 0 0 1 0 0 0 0 0 0 0 0 0 2
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S. Sen et al. / International Biodeterioration & Biodegradation 63 (2009) 135–141
Duncan tests for all fixation results were made after determining the oven dry weight of the leached wood blocks. Solutions 13, 9, and 7 had the lowest fixation levels and were included in the same group. Solutions 5, 2, and 3 were included in a different group. Solutions 10, 6, and 4 had the highest fixation levels and so were included in another group. The fixation levels of Valex in Scots pine and beech woods were the same after the leaching test (Fig. 3). The fixation levels of Sumex and Pinex solutions were lower in beech wood than in Scots pine. Fig. 4 shows that the weight losses of leached wood samples were higher than those in unleached wood specimens. The weight losses in all wood samples exposed to fungal tests showed that the inherent toxic compounds of wood blocks were less than those of the leaching extracts and salts. There was no fungal damage in unleached wood blocks treated with plant extracts and mineral salts, which have high antifungal activity against wood-decay fungi (Table 8).
4. Conclusion
Fig. 3. Average fixation of extracts in leached Scots pine and Beech wood samples (g).
mixed with 1% Bx, 1% Ba, or 1% aluminum sulfate. The highest retention was observed with Sumex and Valex solutions containing 1% Bx and 1% Ba salts. The lowest retention was found with Pinex solution. Adding more than 1% salt did not affect retention. 3.2. Leaching and decay test results Leached and unleached wood samples were examined by two different methods after a 3-month fungal decay test. Macroscopic examination of the penetration of fungal mycelium (according to standard TS ENV 839/2006) was done on the surface and in the core of wood blocks (Table 7). Evaluation of mycelium penetration was made by measuring the extent of fungal attack in samples in petri dishes. When salts were added to the extracts, penetration by the fungal mycelia decreased. Fungal mycelium penetration was deeper in leached wood samples than in unleached samples. In addition, weight loss of wood samples treated with salts and extracts occurred in leached samples but was minimal in unleached samples (Table 7).
In this study, the retention and fixation of plant extracts differed when the extracts were used for wood treatment alone or together with salts. Adding 1% boric acid or borax had a positive effect on retention of valonia oak and sumac leaf extracts, but not Pinus brutia bark extracts. The addition of 3% mineral salts had a negative effect on fixation of all three extracts. Therefore, adding 1% salt to extracts is enough to yield a positive effect. Aluminum sulfate with Pinus brutia bark extracts had a positive effect in Scots pine wood blocks. The use of combined salt solutions from 1% to 3% had a negative effect on retention and fixation. An increase in salt addition of more than 1% caused more leaching of extracts from wood samples, giving them poor protection against fungal attack. There are two main reasons for the differing retention and fixation in Scots pine and beech samples. First, the extracts and salts move separately and are not bound to each other. Second, the plant extracts have a lower specific gravity compared to the metal salts, although the latter dissolved well in hot water. The penetration of extracts into wood is very difficult because of its porous structure. The extracts accumulate on the wood surface and leach easily. It is necessary to obtain permanent high retention and fixation with these plant extracts by using natural materials and
Fig. 4. Average loss of weight in leached and unleached wood samples.
S. Sen et al. / International Biodeterioration & Biodegradation 63 (2009) 135–141
combinations that chemically bond with the extracts and easily penetrate into the wood structure.
References AWPA Standards, E1197, 1999. Standard method of determining the leachability of water-borne wood preservatives. _ Dıg˘rak, M., Ilçim, A., Alma, M.H., S¸en, S., 1998. Antibacterial and antifungal effects of various commercial plant extracts. Pharmaceutical Biology 36, 1–5. _ Dıg˘rak, M., Ilçim, A., Alma, M.H., 2001. Antibacterial and antifungal activities of Turkish medicinal plants. Pharmaceutical Biology 39, 346–350. Hus¸, S., 1969. Forest products chemistry. Istanbul University. Pubic No. 1451. Kurtulmus¸ Press, Istanbul. p.195. Nicholas, D.D., 1973. Wood deterioration and its prevention by preservative treatments. In: Preservatives and preservative systems, vol. II. Syracuse University, New York, ISBN 0-8156-5037-X. 299–343. Pizzi, A., Baecker, A., 1996. A new boron fixation mechanism for environment friendly wood preservatives. No. 6. Holzforschung Vol. 50, 507–510.
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Pizzi, A., 1998. Wood/bark extracts as adhesives and preservatives. In: Bruce, A., Palfreyman, J.W. (Eds.), Forest Products Biotechnology. Taylor & Francis Ltd., Padstow, UK, ISBN 0-7484-0415-5 Chapter 11. S¸en, S., 2001. Determination of wood preservative activities of plant phenolics. Ph.D. Thesis. Zonguldak Karaelmas University. Graduate school of natural and applied sciences. Department of Forestry Industrial Engineering, Bartın, p. 300. S¸en, S., Hafızog˘lu, H., Dıg˘rak, M., 2002a. Investigation of wood preservative activities of plant extracts and tannins as fungicide. KSU Journal of Science and Engineering 5, 99–110. S¸en, S., Hafızog˘lu, H., Kanat, M., 2002b. Investigation of wood preservative activities of plant extracts and tannins as insecticide. KSU Journal of Science and Engineering 5, 111–119. Thevenon, M.F., Pizzi, A., Haluk, J.P., 1997. Non-toxic albumin and soja protein borates as ground-contact wood preservatives. Holz als Roh-und Werkstoff 55, 293–296. Tırak, K., 2006. Increasing Fixation Properties of Plant Extractives and tannins which have natural wood preservation properties. Master Thesis. AIBU Department of Forest Industry Engineering, p. 170. TS ENV 839/2006. Turkish standards. Wood preservatives – determination of the preventive efficacy against wood destroying Basidiomycete fungi. TS 5563 EN 113/1996. Turkish Standards. Wood preservatives-Determination of the toxic values against wood destroying Basidiomycetes cultured on an agar medium.
Contents lists available at ScienceDirect
International Biodeterioration & Biodegradation journal homepage: www.elsevier.com/locate/ibiod
Fixation, leachability, and decay resistance of wood treated with some commercial extracts and wood preservative salts Selim Sen*, Cihat Tascioglu, Kamile Tırak ¨ zce University, Forestry Faculty, 81620 Du ¨ zce, Turkey Du
a r t i c l e i n f o
a b s t r a c t
Article history: Received 11 April 2007 Received in revised form 25 July 2008 Accepted 26 July 2008 Available online 23 September 2008
Beech (Fagus orientalis) and Scots pine (Pinus sylvestris) wood blocks were treated with some commercial extracts as well as water-based wood preservative salts at various concentrations to increase retention and fixation. The penetration, fixation, and antifungal properties of different treatment solutions were compared with statistical analysis. Retention levels of solutions were generally higher for Scots pine wood than beech wood. The highest retention levels were seen in wood treated with sumac leaf extract and oak valonia extract. Leaching tests indicated that both wood types treated with sumac extracts showed higher retention levels than wood treated with the other fruit and bark extract solutions. Adding 1% water-based wood preservative salts to valonia and sumac leaf extracts increased the retention levels. Concentrations of more than 1% did not contribute to retention either individually or with salt additions. Three percent and higher concentrations of wood-preserving salts accelerated and increased the amount of leaching. The results showed that the extract alone was resistant to leaching. Mycological tests showed that all extractives were significantly effective against wood decay. Ó 2008 Elsevier Ltd. All rights reserved.
Keywords: Plant extracts Antifungal Wood treatment Retention Fixation
1. Introduction Human health and environmental concerns have restricted the use of traditional wood preservatives; therefore, much effort has concentrated on finding nontoxic and eco-friendly alternatives (S¸en, 2001; S¸en et al., 2002a). For example, ongoing studies are investigating the use of tannins for nontoxic wood preservatives. The word ‘‘tannin’’ has been used loosely to define two different classes of chemical compounds of mainly phenolic nature: hydrolysable and condensed tannins (Pizzi, 1998). Tannins occur naturally in the bark, fruit, and leaves of plants at various concentrations (Hus¸, 1969). Herbal extracts that have antifungal and insecticide properties (Dıg˘rak et al., 1998; Dıg˘rak et al., 2001) present fixation problems for treated wood. Some methods have proven effective for decreasing the extent of tannin leaching from treated wood (Thevenon et al., 1997; Pizzi and Baecker, 1996). When treating porous wood, the most important property is the preservative viscosity. Reduced viscosity increases liquid retention and therefore the penetration of the treatment solution. However, porous wood acts as a filter by preventing the absorption of large, low-density molecules, which can nullify the effect of increased viscosity (Nicholas, 1973).
* Corresponding author. Tel.: þ903805421137 (3301); þ905057512213 (mobile); fax: þ903805421136. E-mail address: [email protected] (S. Sen). 0964-8305/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.ibiod.2008.07.007
Wood is a porous material and in many respects acts like a filter to liquids flowing through it. Due to the extremely small pore size, in most cases wood can be regarded as an ultra-filter. Thus, it is predicted that wood treatment solutions that contain particulate matter will plug the pores during the impregnation process (Nicholas, 1973). For this reason, it is difficult for the extractives to penetrate into the wood structure (Tırak, 2006). Commercial extracts from valonia oak, sumac leaves, and gallnut powder have been used as raw materials in the Turkish leather industry for many years because of their rich tannin content. Dıg˘rak et al. (1998, 2001) found that some commercial extracts used in the leather industry have positive antimicrobial, antifungal, and insecticidal activities. S¸en (2001) conducted field and laboratory tests of the effectiveness of valonia oak, gallnut powder, and Pinus brutia bark extracts in 1%, 3%, 5%, 7%, and 10% solutions as antifungal agents on spruce, fir, beech, and alder wood blocks. He found that these plant extracts have high antifungal activity, but showed poor fixation in outdoor and laboratory tests. However, concentrations of 4% of commercial plant extracts showed antifungal activity against white-rot (Pleurotus ostreatus) and brown-rot fungi (Phanerochaete chrysosporium) (S¸en et al., 2002a). In addition, extracts at concentrations of 4% showed insecticidal activity against larvae of Rhagium inquisitor (S¸en et al., 2002b). In this study, we investigated plant extracts from leaves of Sicilian sumac (Rhus coriaria L.), valonia oak (Quercus macrolepis KyQ.aegilops L.), and bark of Turkish pine (Pinus brutia Ten.), which
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S. Sen et al. / International Biodeterioration & Biodegradation 63 (2009) 135–141
Table 1 Extract solutions and their pH used in the treatments Valex solutions
pH
Sumex solutions
pH
Pinex solutions
pH
4% 4% 1% 3% 1% 3% 1% 3% 1% 3% 1% 1% 1% 1%
3.75
4% 4% 1% 3% 1% 3% 1% 3% 1% 3% 1% 1% 1% 1%
4.26
4% 4% 1% 3% 1% 3% 1% 3% 1% 3% 1% 1% 1% 1%
3.48
Valex Valex þ Boric acid Boric acid Borax Borax Al2(SO4)3 Al2(SO4)3 CuSO4 CuSO4 Ba þ 1% Bx Ba þ 1% Al2(SO4)3 Bx þ 1% Al2(SO4)3 Ba þ 1% CuSO4
3.14 2.63 5.09 7.28 2.27 2.14 2.58 2.28 4.41 2.61 3.22 2.74
Sumex Sumex þ Boric acid Boric acid Borax Borax Al2(SO4)3 Al2(SO4)3 CuSO4 CuSO4 Ba þ 1% Bx Ba þ 1% Al2(SO4)3 Bx þ 1% Al2(SO4)3 Ba þ 1% CuSO4
4.00 3.76 5.80 7.83 3.13 2.95 3.41 3.12 5.06 2.97 3.52 3.26
Pinex Pinex þ Boric acid Boric acid Borax Borax Al2(SO4)3 Al2(SO4)3 CuSO4 CuSO4 Ba þ 1% Bx Ba þ 1% Al2(SO4)3 Bx þ 1% Al2(SO4)3 Ba þ 1% CuSO4
3.40 3.28 8.30 8.96 3.08 3.11 2.87 2.92 7.46 3.10 4.30 3.02
Al2(SO4)3 – aluminum Sulfate; CuSO4 – copper sulfate.
have been used in the Turkish leather industry for centuries. These plants are abundant, natural sources of tannins. To improve the wood protection effectiveness of extracts, they should be absorbed well into the material, and this process is defined as fixation. Here we investigated the retention, fixation, and fungal resistance of Scots pine and beech wood treated with plant extracts and a combination of boric acid, borax, aluminum sulfate, and copper sulfate. We also attempted to improve the fixation ability of plant extracts using water-based wood preservatives.
solution from the wood surface, and weighed (to the nearest 0.01 g) to determine the retention of each solution. Retention was calculated using the following formula: R ¼
GC 10 kg=m3 V
R ¼
GC ðg; based on oven dry weightÞ 100
2.1. Preparation of test specimens
After calculating retention, samples were weighed and then dried at 103 C.
Table 3 Retention levels of S. pine and Beech wood samples treated with solutions Solutions and concentrations
1
%4 Extract
We used the classic reverse current method to produce the valonia extract (valex), sumac leaf extract (sumex), and pine bark extract (pinex) from Turkey (Tırak, 2006). Bark, leaves, and fruit were broken into small pieces using a grinder. The pieces were then extracted in hot water at 85 5 C for 2 h. Density was determined using a hydrometer, and the extract solution was prepared at 4% concentration. The solution types used were as follows: 4% extract, 4% extract þ 1% salt, 4% extract þ 3% salt, and 4% extract þ 1% salt 1 þ1% salt 2. The names and concentrations of the extracts and salts are provided in Table 1.
2
%4
3
%4
4
%4
5
%4
6
%4
7
%4
8
%4
9
%4
Wood samples were treated using a full-cell pressure process at 1 bar vacuum (30 min) with 8 bar pressure (60 min), followed by 15 min at atmospheric pressure. Treated blocks were air-dried for 7 days to ensure fixation of the chemicals within the test specimens. Untreated blocks were used as controls. Following impregnation, wood samples were removed from the treatment solution, wiped lightly to remove
10 %4 Table 2 Evaluation system for measuring the extent of fungal attacks (TS ENV 839/2006) Value State and appearance 0 1 2
No visible fungal attack or decay Mycelium penetrates into the cross-section of the wood sample Mycelium penetrates 1/5th of the way through the cross-section of wood sample
Wood Retentions samples (kg/m3)
(%)
Valex Sumex Pinex Valex Sumex Pinex
2.2. Preparation of treatment solutions
2.3. Treatment method
T2 T1 100ð%Þ T1
G ¼ (T2 T1): Grams of treatment solution absorbed by the block (initial weight of block subtracted from the initial weight plus the treatment solution absorbed) C: Grams of preservative solutions in 100 g of the treatment solution V: Volume of block in cubic centimeters T2: Sample of weight after treatment T1: Sample of weight before treatment.
2. Materials and methods
Scots pine (Pinus sylvestris) and beech (Fagus orientalis) wood specimens were cut into 50 20 15-mm blocks. All specimens were oven-dried at 103 2 C for 48 h before and after treatment. The plant extracts were obtained from a variety of regions in Anatolia. Valex was obtained from valonia oak (Quercus macrolepis Ky.) produced at the Salihli AR-TU Chemistry Plant. Brutia pine bark powder was obtained from Pinus brutia grown in the Mersin region, and sumac leaf powder was obtained from Rhus coriariae grown in Kahramanmaras. Solutions containing 1% and 3% boric acid (Ba), borax (Bx), aluminum sulfate [Al2(SO4)3], or copper sulfate (CuSO4), and 4% plant extract solutions were prepared. These salt solutions and single extracts were then infiltrated into beech (Fagus orientalis) and Scots pine (P. sylvestris) wood blocks. The tannin contents of the plant extracts used in this study were 34% (cortex Pinus brutia bark), 64% (sumac leaf powder), and 68% (valonia oak powder) (Tırak, 2006).
R ¼
11 %4 12 %4 13 %4
Pine Beech Extract þ %1Ba Pine Beech Extract þ %1 Bx Pine Beech Extract þ %1 AlS Pine Beech Extract þ 1CuS Pine Beech Ext þ %3 Ba Pine Beech Extract þ %3 Bx Pine Beech Extract þ %3 AlS Pine Beech Extract þ %3 CuS Pine Beech Ext þ %1 Ba þ %1 Bx Pine Beech Ext þ %1 Ba þ %1 AlS Pine Beech Ext þ %1 Bx þ %1 AlS Pine Beech Ext þ %1 Ba þ %1 CuS Pine Beech
25 21 46 37 52 40 33 32 36 31 28 28 28 25 19 21 19 19 31 28 26 31 22 23 21 34
40 33 52 46 63 43 29 34 30 25 30 27 30 23 24 29 27 23 29 22 27 28 24 25 22 30
41 13 15 21 11 19 41 27 14 13 18 15 20 13 21 16 19 9 23 21 17 19 16 17 15 21
145 79 238 123 274 134 163 101 183 103 104 63 100 53 68 48 66 40 131 67 112 79 97 60 101 71
240 126 269 150 327 140 140 103 151 85 109 59 109 47 87 64 92 46 120 50 113 69 103 64 105 64
233 45 78 70 58 58 204 87 71 44 65 33 73 26 76 37 64 20 96 48 70 48 68 45 70 45
Ba – boric acid Bx – borax; AlS – aluminum sulfate Al2(SO4)3; CuS – copper sulfate CuSO4.
S. Sen et al. / International Biodeterioration & Biodegradation 63 (2009) 135–141
137
Table 4 ANOVA showing retention and fixation values for Scots pine and beech wood samples after treatment with extracts alone and with salts (based on oven dry weight, g) Solutions and concentrations
Sum of squares
Degree of free
Mean square
F
Sig
0.004 0.017 0.002 0.004 0.007 0.021 0.004 0.003 0.009 0.006 0.005 0.008 0.006
39.32 8.163 27.29 9.707 25.84 25.37 3.829 6.680 29.99 68.85 1.445 1.942 29.01
0.000 0.000 0.000 0.000 0.000 0.000 0.020 0.002 0.000 0.000 0.251 0.146 0.000
0.183 0.031 0.030 0.046 0.072 0.161 0.017 0.023 0.100 0.061 0.017 0.008 0.037
0.003 0.001 0.001 0.002 0.001 0.006 0.001 0.002 0.003 0.010 0.002 0.001 0.004
72.89 37.67 31.21 20.23 53.67 26.79 15.58 15.09 34.47 6.019 7.262 7.941 8.582
0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.003 0.001 0.001 0.000
11 15 15 15 47 15 15 15 47 15 15 15 47
0.010 0.012 0.000 0.002 0.006 0.002 0.008 0.010 0.006 0.000 0.012 0.008 0.008
0.000 0.001 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000
19.87 21.61 1.111 5.026 19.09 13.10 25.00 69.94 27.86 – 38.27 44.95 53.42
0.000 0.000 0.383 0.017 0.000 0.000 0.000 0.000 0.000 – 0.000 0.000 0.000
11 15 15 15 47 15 15 15 47 15 15 15 47
0.006 0.005 0.000 0.006 0.005 0.000 0.008 0.001 0.003 0.000 0.001 0.006 0.002
0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000
16.93 32.83 0.231 25.55 35.84 2.800 79.84 12.61 23.94 1.571 18.77 68.27 47.35
0.001 0.000 0.873 0.000 0.000 0.085 0.000 0.001 0.000 0.248 0.000 0.000 0.000
BG
WG
Total
BG
WG
Total
BG
WG
0.305 0.413 0.132 0.105 2.106 1.565 0.041 0.053 3.092 1.197 0.021 0.049 2.237
0.082 0.472 0.045 0.101 0.618 0.576 0.099 0.074 0.782 0.162 0.139 0.236 0.585
0.387 0.884 0.177 0.206 2.725 2.140 0.140 0.127 3.874 1.359 0.160 0.285 2.822
2 3 3 3 12 3 3 3 12 3 3 3 12
21 28 28 28 91 28 28 28 91 28 28 28 91
23 31 31 31 103 31 31 31 103 31 31 31 103
0.153 0.138 0.044 0.035 0.176 0.522 0.014 0.018 0.258 0.399 0.007 0.016 0.186
0.367 0.093 0.089 0.137 0.865 0.483 0.050 0.068 1.197 0.183 0.051 0.023 0.450
0.053 0.023 0.027 0.063 0.122 0.168 0.030 0.042 0.263 0.284 0.065 0.027 0.398
0.419 0.116 0.116 0.201 0.987 0.651 0.080 0.110 1.460 0.467 0.116 0.051 0.847
2 3 3 3 12 3 3 3 12 3 3 3 12
21 28 28 28 91 28 28 28 91 28 28 28 91
23 31 31 31 103 31 31 31 103 31 31 31 103
0.019 0.036 0.000 0.005 0.064 0.006 0.025 0.029 0.065 0.000 0.035 0.023 0.093
0.004 0.007 0.000 0.004 0.011 0.002 0.004 0.002 0.008 0.000 0.004 0.002 0.006
0.024 0.043 0.001 0.009 0.075 0.008 0.029 0.031 0.073 0.000 0.039 0.025 0.099
2 3 3 3 11 3 3 3 11 3 3 3 11
9 12 12 12 36 12 12 12 36 12 12 12 36
0.012 0.015 0.000 0.017 0.052 0.001 0.025 0.004 0.032 0.000 0.003 0.018 0.027
0.003 0.002 0.000 0.003 0.005 0.002 0.001 0.001 0.004 0.000 0.001 0.001 0.002
0.015 0.016 0.000 0.020 0.057 0.003 0.026 0.005 0.037 0.000 0.004 0.019 0.029
2 3 3 3 11 3 3 3 11 3 3 3 11
9 12 12 12 36 12 12 12 36 12 12 12 36
Retentions Scots pine wood samples Extracts Pinex 1% salt addition 3% salt addition 1% þ 1% salt add All valex solut. Sumex 1% salt addition 3% salt addition 1% þ 1% salt add All sumex solut. Valex 1% salt addition 3% salt addition 1% þ 1% salt add All pinex solut. Beech wood samples Extracts Pinex 1% salt addition 3% salt addition 1% þ 1% salt add All valex solut. Sumex 1% salt addition 3% salt addition 1% þ 1% salt add All sumex solut. Valex 1% salt addition 3% salt addition 1% þ 1% salt add All pinex solut. Fixation Scots pine wood samples Extracts Pinex 1% salt addition 3% salt addition 1% þ 1% salt add All valex solut. Sumex 1% salt addition 3% salt addition 1% þ 1% salt add All sumex solut. Valex 1% salt addition 3% salt addition 1% þ 1% salt add All pinex solut. Beech wood samples Extracts Pinex 1% salt addition 3% salt addition 1% þ 1% salt add All valex solut. Sumex 1% salt addition 3% salt addition 1% þ 1% salt add All sumex solut. Valex 1% salt addition 3% salt addition 1% þ %1 salt add All of pinex sol. BG: between groups, WG: within groups. 2.4. Leaching test The leaching test was conducted on four samples of eight impregnated and four samples of eight untreated control wood blocks. Leaching samples were placed into 600 ml of distilled water for 24 h. This procedure was then repeated with fresh water for 14 days. The leached samples were collected after water replacement and dried at 103 C for 48 h (AWPA Standards, E11-97, 1999). All leached and unleached samples were exposed to fungal test.
fungi, Trametes versicolor (Mad-697), and Scots pine samples were exposed to brown-rot fungi, Gloeophyllum trabeum (Mad-617-R), according to TS 5563 EN 113/1996. All specimens were incubated for 12 weeks at 25 C and then brushed and dried at 103 C. Evaluation of fungal performance was carried out by visual inspection. Mycelium penetration depth was measured using a compass according to TS ENV 839/2006. Table 2 shows the evaluation standards used for measuring the extent of decay caused by fungal attack.
2.5. Wood-decay test
2.6. Statistical analysis
Four unleached and four leached treated specimens and their respective untreated controls were exposed to fungal attack after leached tests. Beech wood was exposed in petri dishes containing agar medium inoculated with white-rot
Retention and leaching and weight loss values were evaluated using a computerized SPSS 13.0 statistical program and tested with Univarite, followed by a Duncan test with a 95% confidence interval.
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S. Sen et al. / International Biodeterioration & Biodegradation 63 (2009) 135–141 Table 6 Duncan test results of the groups concerned with retentions and fixations
Fig. 1. The average retentions of extractives in Scots pine and Beech wood samples.
3. Results 3.1. Retention results Retention levels of treated Scots pine and Beech wood are shown in Table 3 as kilograms per cubic meter and percentages. The highest retention of the solutions was observed in the Scots pine wood samples. The retention rate of plant extract solutions was the highest in sumac leaves (Sumex) and valonia oak (Valex). Pinus brutia bark extract (Pinex) had the lowest retention. When the extracts were used alone (i.e., without salts), retention increased to 66% for Valex, 114% for Sumex, and 188% for Pinex. A 1% Ba or 1% Bx plus Valex or Sumex extract further increased the retention. However, Ba and Bo had a negative effect with Pinex extract. With aluminum sulfate and Valex, the increase in retention was limited, and there was a decrease in wood treated with Sumex and aluminum sulfate. The highest retention increase was obtained with Pinex and 1% aluminum sulfate. Other mineral salts gave different retention increases of between 20 and 80%. In general, 1%
Factor
Treatment
Retentions
Groups
Fixations
Species
Scotch pine Beech
0.408 0.376
a* b
– –
Solution groups
Valex Sumex Pinex
0.436 0.467 0.272
b a c
0.0324 0.0428 0.0316
a b a
Solutions
%4 %4 %4 %4 %4 %4 %4 %4 %4 %4 %4 %4 %4
0.428 0.535 0.561 0.488 0.362 0.372 0.351 0.316 0.291 0.371 0.357 0.308 0.354
c a a b d d d e e d d e d
0.1338 0.0192 0.0188 0.0508 0.0146 0.0492 0.0079 0.0300 0.0038 0.0458 0.0608 0.0258 0.0025
k e e h d h c g c h i f c
Ext Ext þ %1 Ext þ %1 Ext þ %1 Ext þ %1 Ext þ %3 Ext þ %3 Ext þ %3 Ext þ %3 Ext þ %1 Ext þ %1 Ext þ %1 Ext þ %1
Ba Bx Al. Sulp. Cu. Sulp. Ba Bx Al. Sulp. Cu. Sulp. Ba þ %1 Bx Ba þ %1 AlS Bx þ %1 AlS Ba þ %1 CuS
Groups
‘*’ means within each factor and column followed same letter are not significantly different (a ¼ 0.05). Based on oven dry weight.
Bo, 1% Ba, 1% Al2(SO4)3, or 1% CuSO4 added to Valex and Sumex (but not Pinex) extract had a positive effect on retention. A one-way ANOVA for retention and fixation in Scots pine and beech wood samples is shown in Table 4. The results show that retention did not vary significantly in Sumex and Pinex solutions with added 3% Ba, 3% Bx, 3% Al2(SO4)3, or 3% CuSO4 in Scots pine wood. However, differences in fixation were not significant between the solution groups containing 1% or 3% salts in Scots pine wood. In addition, there were no significant differences in fixation between Valex solutions with 3% added salts, Sumex solution with 1% added salts, and Pinex solutions with 1% added salts in beech wood samples. The results of fixation and retention in other solutions with added salts were significant. The average retention results are shown in Fig. 1. Higher retention was found for Valex and Sumex solutions in Scots pine and beech wood blocks. All three extracts also had higher retention in Scots pine. Two-way and three-way interactions for retention and fixation in terms of tree species, extract, and treatment solutions were
Table 5 Analyses of variances (ANOVA) for the effects of tree species, extractive species and preservative solutions on variables (retention, fixation) (p < 0.001) Variable
Source
Retention
Tree species Extractives Solutions Tree species þ extractives Tree species þ solutions Extractives þ solutions Tree species þ extractives þ solutions
Mean square
F
Sign
0.166 4.533 4.241 0.022 0.976 3.558 1.113
1 2 12 2 12 24 24
0.166 2.266 0.353 0.011 0.081 0.148 0.046
32.662 446.151 69.578 2.144 16.010 29.185 9.131
0.000 0.000 0.000 0.118 0.000 0.000 0.000
2.763 17.396
544 621
0.005 –
– –
– –
Tree species Extractives Solutions Tree species þ extractives Tree species þ solutions Extractives þ solutions Tree spec. þ extracts þ solutions
0.011 0.008 0.355 0.006 0.064 0.169 0.033
1 2 12 2 12 24 24
0.011 0.004 0.030 0.003 0.005 0.007 0.001
61.170 22.027 161.437 16.821 29.136 38.385 7.585
0.000 0.000 0.000 0.000 0.000 0.000 0.000
Error Corrected total
0.043 0.689
234 311
0.000 –
– –
– –
Error Corrected total Fixation
Dependent variable: based on oven dry weight.
Sum of squares
Degree of free
S. Sen et al. / International Biodeterioration & Biodegradation 63 (2009) 135–141
139
Table 8 Weight losses (%) due to fungus-induced decay No. Solutions
Valex S. Pine L
1 2 3 4 5 6 7 8 9 10 11 12 13
%4 Extractive %4 Extractive þ %1 Ba %4 Extractive þ %1 Bx %4 Extractive þ %1 Al. Sulp. %4 Extractive þ %1 Cu. Sulp. %4 Extractive þ %3 Ba %4 Extractive þ %3 Bx %4 Extractive þ %3 Al. Sulp. %4 Extractive þ %3 Cu. Sulp. %4 Extractive þ %1 Ba þ %1 Bx %4 Extractive þ %1 Ba þ %1 Al. Sulp. %4 Extractive þ %1 Bx þ %1 Al. Sulp. %4 Extractive þ %1 Ba þ %1 Cu. Sulp. Control samples (no treatment)
Sumex
Pinex
Beech S.Pine Beech S. Pine
U L
U L
U L
16 5 31 4 18 6 11 4 16 2 15 8 9 3 18 3 10 6 11 6 24 7 31 8 36 2 7 2 28 3 14 12 15 13 12 2 15 4 17 3 9 4 25 2 16 14 18 2 27 1 34 1 25 0 18 4 16 3 17 2 34 3 15 3 13 8 23 4 18 2 18 6 35 1 26 2 34 1 37 31 38 32 33 25
29 14 16 26 29 15 16 15 25 15 16 15 36 32
Beech
U L
U L
13 7 9 14 1 3 4 13 0 3 8 2 0 32
11 8 9 10 4 6 9 17 1 8 12 4 1 21
23 36 13 21 18 27 19 26 16 16 18 29 35 27
U
25 8 16 5 15 8 16 6 29 2 13 5 20 3 15 2 27 0 13 3 33 1 14 3 34 1 29 24
L: leached; U: unleached.
Fig. 2. (a) The average retention of solutions in Scots pine and Beech wood samples; (b) the average retentions of solutions in terms of extract used.
investigated with SPSS 13.0 with univariate analysis (Table 5). We used a completely randomized design (CRD) with eight replications for retentions as net weight of salt, and four replications for fixation. The interactions of tree species, solution, and concentration with retention were significant at the 95% confidence level. Twoway interactions with tree species–concentration and solution– concentration were significant, whereas interactions between tree species and solution were not. The three-way interaction of tree species–solution–concentration was significant at the 95% confidence level. All one-way and two-way interactions were significant at the same confidence level for tree species, solutions, and concentration in the fixation tests. There was a positive effect of a concentration of 1% adding salts to plant extracts in terms of wood protection. Results of a Duncan test showed that when the salt concentration increased, protection also increased (Table 6). However, there were no significant effects of the impregnated solutions with high and low salt concentrations in leached wood samples in terms of fungal decay. Fig. 2a shows retention by tree species. Fig. 2b shows retention in terms of solutions used. The interaction results of extracts alone and together with salts show that Valex and Sumex with 1% Bo were the most effective in wood. Retention was higher in Scots pine, a softwood species, than in beech. In addition, retention increased when plant extracts were
Table 7 Evaluation of mycelium penetration in Scots pine wood inoculated with G. trabeum and in beech wood inoculated with T. versicolor. No.
Solutions
Valex
Sumex
S. Pine 1 2 3 4 5 6 7 8 9 10 11 12 13
%4 Extractive %4 Extractive þ %1 Ba %4 Extractive þ %1 Bx %4 Extractive þ %1 Al. Sulp. %4 Extractive þ %1 Cu. Sulp. %4 Extractive þ %3 Ba %4 Extractive þ %3 Bx %4 Extractive þ %3 Al. Sulp. %4 Extractive þ %3 Cu. Sulp. %4 Extractive þ %1 Ba þ %1 Bx %4 Extractive þ %1 Ba þ %1 Al. Sulp. %4 Extractive þ %1 Bx þ %1 Al. Sulp. %4 Extractive þ %1 Ba þ %1 Cu. Sulp. Control Samples (without treatment)
L: leached U: unleached.
L 2 1 1 1 2 1 1 2 2 1 2 2 2 2
Beech U 1 0 0 1 0 1 1 0 0 0 0 0 0 2
L 2 1 1 2 1 1 1 1 2 1 1 2 1 2
Pinex
S. Pine U 0 0 0 1 0 1 0 1 0 0 0 0 0 2
L 2 1 1 2 2 1 1 1 2 1 2 2 2 2
Beech U 0 0 0 1 0 0 0 0 0 0 0 1 0 2
L 2 1 1 2 2 1 1 1 2 1 1 1 2 2
S. Pine U 1 0 1 1 0 0 0 1 0 0 0 0 0 2
L 2 1 1 2 1 2 1 2 1 1 1 2 2 2
Beech U 1 0 0 1 0 0 0 1 0 0 0 0 0 2
L 2 1 1 2 2 1 1 1 2 1 2 1 2 2
U 1 0 0 1 0 0 0 0 0 0 0 0 0 2
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Duncan tests for all fixation results were made after determining the oven dry weight of the leached wood blocks. Solutions 13, 9, and 7 had the lowest fixation levels and were included in the same group. Solutions 5, 2, and 3 were included in a different group. Solutions 10, 6, and 4 had the highest fixation levels and so were included in another group. The fixation levels of Valex in Scots pine and beech woods were the same after the leaching test (Fig. 3). The fixation levels of Sumex and Pinex solutions were lower in beech wood than in Scots pine. Fig. 4 shows that the weight losses of leached wood samples were higher than those in unleached wood specimens. The weight losses in all wood samples exposed to fungal tests showed that the inherent toxic compounds of wood blocks were less than those of the leaching extracts and salts. There was no fungal damage in unleached wood blocks treated with plant extracts and mineral salts, which have high antifungal activity against wood-decay fungi (Table 8).
4. Conclusion
Fig. 3. Average fixation of extracts in leached Scots pine and Beech wood samples (g).
mixed with 1% Bx, 1% Ba, or 1% aluminum sulfate. The highest retention was observed with Sumex and Valex solutions containing 1% Bx and 1% Ba salts. The lowest retention was found with Pinex solution. Adding more than 1% salt did not affect retention. 3.2. Leaching and decay test results Leached and unleached wood samples were examined by two different methods after a 3-month fungal decay test. Macroscopic examination of the penetration of fungal mycelium (according to standard TS ENV 839/2006) was done on the surface and in the core of wood blocks (Table 7). Evaluation of mycelium penetration was made by measuring the extent of fungal attack in samples in petri dishes. When salts were added to the extracts, penetration by the fungal mycelia decreased. Fungal mycelium penetration was deeper in leached wood samples than in unleached samples. In addition, weight loss of wood samples treated with salts and extracts occurred in leached samples but was minimal in unleached samples (Table 7).
In this study, the retention and fixation of plant extracts differed when the extracts were used for wood treatment alone or together with salts. Adding 1% boric acid or borax had a positive effect on retention of valonia oak and sumac leaf extracts, but not Pinus brutia bark extracts. The addition of 3% mineral salts had a negative effect on fixation of all three extracts. Therefore, adding 1% salt to extracts is enough to yield a positive effect. Aluminum sulfate with Pinus brutia bark extracts had a positive effect in Scots pine wood blocks. The use of combined salt solutions from 1% to 3% had a negative effect on retention and fixation. An increase in salt addition of more than 1% caused more leaching of extracts from wood samples, giving them poor protection against fungal attack. There are two main reasons for the differing retention and fixation in Scots pine and beech samples. First, the extracts and salts move separately and are not bound to each other. Second, the plant extracts have a lower specific gravity compared to the metal salts, although the latter dissolved well in hot water. The penetration of extracts into wood is very difficult because of its porous structure. The extracts accumulate on the wood surface and leach easily. It is necessary to obtain permanent high retention and fixation with these plant extracts by using natural materials and
Fig. 4. Average loss of weight in leached and unleached wood samples.
S. Sen et al. / International Biodeterioration & Biodegradation 63 (2009) 135–141
combinations that chemically bond with the extracts and easily penetrate into the wood structure.
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