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Using Kraft Black Liquor as a Wood Preservative
Available online at www.sciencedirect.com
ScienceDirect Procedia - Social and Behavioral Sciences 195 (2015) 2177 – 2180
World Conference on Technology, Innovation and Entrepreneurship
Using Kraft Black Liquor as A Wood Preservative Sefa Durmaza,*, Emir Erisirb, Umit C. Yildiza, O. Caglar Kurtulusab a
Deparment of Forest Industry Engineering, Karadeniz Technical University, Trabzon-61080, Turkey Department of Pulp and Paper Technology, Karadeniz Technical University, Trabzon-61080, Turkey ab Deparment of Forest Industry Engineering, Kastamonu University, Kastamonu-37200, Turkey
b
Abstract Under appropriate conditions, wood is degraded easily due to the diversity of biological agents. One way to protect wood from these agents is to impregnate the wood with chemicals. However, increasing environmental pressure has caused a restriction on the use of toxic chemicals. In recent years, researchers have been looking for environmentally friendly preservative chemicals, modification and impregnation methods to develop wood properties such as the durability, water absorption, and dimensional stability. In this study, the remaining Kraft black liquor was employed to Scots pine sapwood (Pinus slyvestris L.) specimens as a wood preservative to enhance the wood durability against biological agents. The black liquor used in this study was obtained from the pre-hydrolysis Kraft pulping process. Various concentrations were used for black liquor; 2.5%, 5%, and 7.5% respectively. The test specimens were impregnated in a small scale impregnation container using a vacuum of 650 mm/Hg for 30 mins. Both test and control wood samples were tested for resistance to brown rot fungus; Coniophora puteana and Poria placenta. Six weeks of exposure to brown rot fungus, C. puteana and P. placenta, resulted in noteworthy weight loss of control samples compared to test samples. After six weeks of exposure to both fungi, the weight loss of control samples were more than 25%, while the weight loss of test samples were less than 3%. The most effective results were obtained at 5% concentration. These results indicate that black liquor enhances the durability of Scots pine sapwood. It can be stated that the carbohydrate degradation products, resin and fatty acids, extractives, and the inorganic materials in the black liquor used in the process showed inhibiting fungal activity. © byby Elsevier Ltd.Ltd. This is an open access article under the CC BY-NC-ND license © 2015 2015The TheAuthors. Authors.Published Published Elsevier (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of Istanbul University. Peer-review under responsibility of Istanbul Univeristy. Keywords: Coniophora puteana, Kraft black liquor, Poria placenta, Scots pine, wood protection
* Corresponding author. Tel.: +9-462-377-1536; fax: +9-462-325-7499. E-mail address: [email protected]
1877-0428 © 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of Istanbul Univeristy. doi:10.1016/j.sbspro.2015.06.291
2178
Sefa Durmaz et al. / Procedia - Social and Behavioral Sciences 195 (2015) 2177 – 2180
1. Introduction Wood is still one of the most significant materials found in the natural habitat abundantly. Due to increasing environmental pressure, petroleum-derived materials are being abandoned; therefore the demand for wood is rising. However, under appropriate conditions, wood is easily degraded by the diversity of biological organisms including fungi, insects, bacteria, and mould (Schmidt, 2006). To protect the wood from these organisms, it has to be treated with preservatives (Mai et al (2004). Copper is a fundamental element for higher forms of plant and living cells, because it is involved in a lot of physiological processes such as photosynthesis (Alaoui-Sossé et al., 2004; Vanassche and Clijsters, 1990). However, the excess amount of copper creates a toxic effect as it is used as an algaecide, bactericide, fungicide, insecticide, and moldicide (Freeman and McIntyre, 2008). The use of copper-based preservatives increased during the 1970s and 1980s. One of the most effective chemicals among the copper-based preservatives is copper, chrome, and arsenic (CCA). Beside this, pesticide manufacturers phased out the treatment of CCA for residential usage and in children’s' play areas due to the toxic chemicals it contains. Following this, the CCA usage has been limited since December 31, 2003 (EPA, 13.02.15). To provide effective protection to the wood, new preservative chemicals, modifications and impregnation methods have been developed. Preservatives containing organic material could be easily detoxified naturally (Onuorah, 2000). Extractives in plants such as alkaloids, lectins, phenols, polypeptides and terponoids can be used for different applications (Singh and Singh, 2011). Bark, heartwood of durable species, fruits, seeds, and fungal extracts have been investigated to evaluate their natural preservatives (Yang, 2009; Tascioglu et al., 2013; Kartal et al., 2006; Mohan et al., 2008). Within the chemical wood pulping process; Kraft process, which cooking liquor is made up of mainly sodium hydroxide and sodium sulfide with a cooking pH of 13.5, is the most practiced process all over the world (Gierer, 1980; Berglin and Berntsson, 1998). Generally in Kraft pulping, softwoods are preferred in order to produce unbleached wood pulp. In the pulping process, the lignin can easily be dissolved to remove wood fibers without any mechanical forces. Hemicelluloses, lignin, extractives, and the inorganic materials used in the process compose of black liquor which is the waste product of the wood pulping process (Sjöström, 1983). Lignin and carbohydrate products in the Kraft black liquor is generally utilized as fuel for energy production (Berglin and Berntsson, 1998). The objective of the present study is to investigate the utility of black liquor as a wood preservative. It is renowned that the black liquor is used to supply energy for the production of Kraft pulp. In spite of many studies regarding the role of black liquor in the energy production, the utility of this waste product as a wood preservative is largely unexplored. When compared to copper-based preservatives, it can be stated that there is no toxic effect against the environment due to no heavy metal containing properties. To clarify the effect on wood, Scots pine sapwood was subjected to brown-rot fungus; both Coniophora puteana and Poria placenta. Following the biological rotting test, its effect was evaluated according to the weight loss of test and control samples. 2. Materials and Methods 2.1 Wood Material Scots pine wood (Pinus sylvestris L.) samples were used for both Kraft process and decay resistance testing. While sapwood portions of Scots pine wood were used for the decay resistance, both sapwood and heartwood samples were used for the Kraft process. Wood samples with minor modifications, 30×15×2 mm 3, were cut from sapwood portions of Scots pine for the decay resistance test. 2.2 Impregnation Process Scots pine sapwood samples treated with Kraft black liquor at different concentrations (2.5, 5.0, and 7.5%).
Sefa Durmaz et al. / Procedia - Social and Behavioral Sciences 195 (2015) 2177 – 2180
2179
Impregnation was implemented in a small scale impregnation container using a vacuum of 650 mm/Hg for 30 mins followed by atmospheric pressure for 15 mins. Afterwards samples were conditioned at 20 oC and 65 % RH for 3 weeks. Retention of black liquor was calculated with Eq. 1: R= [(GxC) /V] x10 g/cm3
(1)
Where R is retention, G is the difference between sample weight before and after the impregnation, C is concentration of black liquor (%), and V is volume of samples. 2.3 Decay Resistance Test Untreated and treated wood samples were exposed to two different brown-rot fungi according to EN 113 standards. Brown-rot fungi, Coniophera puteana (Schumach.) P. Karst. (Mad-515) and Postia placenta (Fr.) Lars.& Lomb. (Mad-698-R) were used in this experiment. Both fungi were grown on 4,8% malt extract agar (MEA) medium. The media was steam sterilized at 120 oC for 20 mins before it was poured into each petri dish. After inoculation, petri dishes were kept at 23±2 oC and 65±5 % relative humidity until fungi completely covered the dishes. Following the test, the control samples’ oven-dried weights were determined. Each of them steam sterilized at 120 oC for 20mins. Eight controlled and treated samples were exposed to fungal testing. After the six weeks of exposure to both fungi, the weight loss of both control and treated samples was calculated from the dry weight before and after the treatment. 3. Result and Discussion 3.1 Retention Different concentrations of black liquor retentions were calculated on the uptake of liquid on treated wood samples, given in Table 1. As concentration increased, the retention amount also increased, parallel to liquid concentrations. Table 1 Retentions of different black liquor concentrations (gr/cm3) Concentrations %
Retentions
2.5
0.13
5
0.25
7.5
0.6
3.2 Mass losses Mass losses caused by C. puteana and P. placenta on wood samples treated with black liquor at 3 different concentration levels are shown in Table 2. The mass losses of untreated control samples exposed to C. puteana, and P. placenta were 29.5, and 26.3, respectively. When the mass losses of test and control specimens were investigated, C. puteana induced much higher mass loss. This indicates that C. puteana is more aggressive compared to the P. placenta fungi. When the concentration was increased, mass losses did not reduce. Wood protection is not always provided with the highest level retentions of preservatives (Palantini and Susco, 2004). Above 5% concentration, the black liquor showed an opposite effect against brown-rot fungus. The lowest mass loss was determined at 5% concentration.
2180
Sefa Durmaz et al. / Procedia - Social and Behavioral Sciences 195 (2015) 2177 – 2180 Table 2 Mass loss of samples Black Liquor
Coniophora
Concentration
puteana %
Poria placenta %
2.5%
0.6
0.4
5%
0.35
0.15
7.5%
2,9
2.2
Control
29.5
26.3
According to previous studies, Scots pine wood black liquor composes of lignin, hydroxyl carboxylic acids, acetic acid, formic acid, turpentine, resin and/or fatty acids, as well as miscellaneous products (Sjöström, 1983). It is thought that this mixture shows an inhibition against both brown-rot fungi. It can be stated that black liquor enhances the biological durability of Scots pine sapwood. 4. Conclusions The aim of this study is to develop an alternative preservative against copper-based chemicals. Black liquor is composed of several components formed by the degradation of wood. According to wood decay testing, mass loss of test and control samples showed that black liquor inhibits fungal activity and improves durability against these brown-rot fungi. In our next study, large scale timbers will be impregnated with black liquor. Following this its mechanical and physical properties will be investigated. References Alaoui-Sossé, B., Genet, P., Vinit-Dunand, F., Toussaint, M-L., Epron, D., Badot, P-M. (2004). Effect of copper on growth in cucumber plants (Cucumis sativus) and its relationships with carbohydrate accumulation and changes in ion contents. Plant Science, 166(5), 8-1213 Berglin, N., Berntsson, T. (1998). CHP in the pulp industry using black liquor gasification: thermodynamic analysis. Appl Therm Eng. 18(11), 61-947. Freeman, MH., McIntyre, CR. (2008). A comprehensive review of copper-based wood preservatives. Forest Prod J., 58(11), 6-27. Gierer, J. (1980). Chemical aspects of Kraft pulping. Wood Science and Technology.14(4), 241-66. Kartal, SN., Hwang, W-J., Imamura, Y. Sekine, Y. (2006). Effect of essential oil compounds and plant extracts on decay and termite resistance of wood. Holz als Roh- und Werkstoff, 64(6), 61-455 Mai, C., Kues, U., Militz, H. (2004). Biotechnology in the wood industry. Applied microbiology and biotechnology, 63(5), 94-477. Mohan, D., Shi, J., Nicholas, DD., Pittman, CU., Jr., Steele, PH., Cooper, JE. (2008). Fungicidal values of bio-oils and their lignin-rich fractions obtained from wood/bark fast pyrolysis. Chemosphere. 71(3), 65-456. Onuorah, EO. (2000). The wood preservative potentials of heartwood extracts of Milicia excelsa and Erythrophleum suaveolens. Bioresource Technology. 75(2), 3-171. Palantini, S., Susco, D., (2004). A new wood preservative based on heated oil treatment combined with triazole fungicides developed for aboveground conditions, International Biodeterioration & Biodegradation, 54, 337-342. Schmidt, O. (2006). Wood and Tree Fungi: Biology, Damage, Protection, and Use,7th ed., Springer, Berlin Sjöström, E. (1983). Wood Chemistry Fundamentals and Applications. Elsevier. Singh, T., Singh, AP. (2011). A review on natural products as wood protectant. Wood Science and Technology, 46(5), 70-851. Tascioglu, C., Yalcin, M., Sen, S., Akcay, C. (2013). Antifungal properties of some plant extracts used as wood preservatives. International Biodeterioration & Biodegradation, 85, 8-23. Vanassche, F., Clijsters, H. (1990). Effects of Metals on Enzyme-Activity in Plants. Plant Cell Environ, 13(3), 195-206. Yang, DQ. (2009). Potential utilization of plant and fungal extracts for wood protection. Forest Prod J., 59(4), 97-103. URL-1. http://www.epa.gov/oppad001/reregistration/cca/alternativestocca.htm . (13.02.2015).
ScienceDirect Procedia - Social and Behavioral Sciences 195 (2015) 2177 – 2180
World Conference on Technology, Innovation and Entrepreneurship
Using Kraft Black Liquor as A Wood Preservative Sefa Durmaza,*, Emir Erisirb, Umit C. Yildiza, O. Caglar Kurtulusab a
Deparment of Forest Industry Engineering, Karadeniz Technical University, Trabzon-61080, Turkey Department of Pulp and Paper Technology, Karadeniz Technical University, Trabzon-61080, Turkey ab Deparment of Forest Industry Engineering, Kastamonu University, Kastamonu-37200, Turkey
b
Abstract Under appropriate conditions, wood is degraded easily due to the diversity of biological agents. One way to protect wood from these agents is to impregnate the wood with chemicals. However, increasing environmental pressure has caused a restriction on the use of toxic chemicals. In recent years, researchers have been looking for environmentally friendly preservative chemicals, modification and impregnation methods to develop wood properties such as the durability, water absorption, and dimensional stability. In this study, the remaining Kraft black liquor was employed to Scots pine sapwood (Pinus slyvestris L.) specimens as a wood preservative to enhance the wood durability against biological agents. The black liquor used in this study was obtained from the pre-hydrolysis Kraft pulping process. Various concentrations were used for black liquor; 2.5%, 5%, and 7.5% respectively. The test specimens were impregnated in a small scale impregnation container using a vacuum of 650 mm/Hg for 30 mins. Both test and control wood samples were tested for resistance to brown rot fungus; Coniophora puteana and Poria placenta. Six weeks of exposure to brown rot fungus, C. puteana and P. placenta, resulted in noteworthy weight loss of control samples compared to test samples. After six weeks of exposure to both fungi, the weight loss of control samples were more than 25%, while the weight loss of test samples were less than 3%. The most effective results were obtained at 5% concentration. These results indicate that black liquor enhances the durability of Scots pine sapwood. It can be stated that the carbohydrate degradation products, resin and fatty acids, extractives, and the inorganic materials in the black liquor used in the process showed inhibiting fungal activity. © byby Elsevier Ltd.Ltd. This is an open access article under the CC BY-NC-ND license © 2015 2015The TheAuthors. Authors.Published Published Elsevier (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of Istanbul University. Peer-review under responsibility of Istanbul Univeristy. Keywords: Coniophora puteana, Kraft black liquor, Poria placenta, Scots pine, wood protection
* Corresponding author. Tel.: +9-462-377-1536; fax: +9-462-325-7499. E-mail address: [email protected]
1877-0428 © 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of Istanbul Univeristy. doi:10.1016/j.sbspro.2015.06.291
2178
Sefa Durmaz et al. / Procedia - Social and Behavioral Sciences 195 (2015) 2177 – 2180
1. Introduction Wood is still one of the most significant materials found in the natural habitat abundantly. Due to increasing environmental pressure, petroleum-derived materials are being abandoned; therefore the demand for wood is rising. However, under appropriate conditions, wood is easily degraded by the diversity of biological organisms including fungi, insects, bacteria, and mould (Schmidt, 2006). To protect the wood from these organisms, it has to be treated with preservatives (Mai et al (2004). Copper is a fundamental element for higher forms of plant and living cells, because it is involved in a lot of physiological processes such as photosynthesis (Alaoui-Sossé et al., 2004; Vanassche and Clijsters, 1990). However, the excess amount of copper creates a toxic effect as it is used as an algaecide, bactericide, fungicide, insecticide, and moldicide (Freeman and McIntyre, 2008). The use of copper-based preservatives increased during the 1970s and 1980s. One of the most effective chemicals among the copper-based preservatives is copper, chrome, and arsenic (CCA). Beside this, pesticide manufacturers phased out the treatment of CCA for residential usage and in children’s' play areas due to the toxic chemicals it contains. Following this, the CCA usage has been limited since December 31, 2003 (EPA, 13.02.15). To provide effective protection to the wood, new preservative chemicals, modifications and impregnation methods have been developed. Preservatives containing organic material could be easily detoxified naturally (Onuorah, 2000). Extractives in plants such as alkaloids, lectins, phenols, polypeptides and terponoids can be used for different applications (Singh and Singh, 2011). Bark, heartwood of durable species, fruits, seeds, and fungal extracts have been investigated to evaluate their natural preservatives (Yang, 2009; Tascioglu et al., 2013; Kartal et al., 2006; Mohan et al., 2008). Within the chemical wood pulping process; Kraft process, which cooking liquor is made up of mainly sodium hydroxide and sodium sulfide with a cooking pH of 13.5, is the most practiced process all over the world (Gierer, 1980; Berglin and Berntsson, 1998). Generally in Kraft pulping, softwoods are preferred in order to produce unbleached wood pulp. In the pulping process, the lignin can easily be dissolved to remove wood fibers without any mechanical forces. Hemicelluloses, lignin, extractives, and the inorganic materials used in the process compose of black liquor which is the waste product of the wood pulping process (Sjöström, 1983). Lignin and carbohydrate products in the Kraft black liquor is generally utilized as fuel for energy production (Berglin and Berntsson, 1998). The objective of the present study is to investigate the utility of black liquor as a wood preservative. It is renowned that the black liquor is used to supply energy for the production of Kraft pulp. In spite of many studies regarding the role of black liquor in the energy production, the utility of this waste product as a wood preservative is largely unexplored. When compared to copper-based preservatives, it can be stated that there is no toxic effect against the environment due to no heavy metal containing properties. To clarify the effect on wood, Scots pine sapwood was subjected to brown-rot fungus; both Coniophora puteana and Poria placenta. Following the biological rotting test, its effect was evaluated according to the weight loss of test and control samples. 2. Materials and Methods 2.1 Wood Material Scots pine wood (Pinus sylvestris L.) samples were used for both Kraft process and decay resistance testing. While sapwood portions of Scots pine wood were used for the decay resistance, both sapwood and heartwood samples were used for the Kraft process. Wood samples with minor modifications, 30×15×2 mm 3, were cut from sapwood portions of Scots pine for the decay resistance test. 2.2 Impregnation Process Scots pine sapwood samples treated with Kraft black liquor at different concentrations (2.5, 5.0, and 7.5%).
Sefa Durmaz et al. / Procedia - Social and Behavioral Sciences 195 (2015) 2177 – 2180
2179
Impregnation was implemented in a small scale impregnation container using a vacuum of 650 mm/Hg for 30 mins followed by atmospheric pressure for 15 mins. Afterwards samples were conditioned at 20 oC and 65 % RH for 3 weeks. Retention of black liquor was calculated with Eq. 1: R= [(GxC) /V] x10 g/cm3
(1)
Where R is retention, G is the difference between sample weight before and after the impregnation, C is concentration of black liquor (%), and V is volume of samples. 2.3 Decay Resistance Test Untreated and treated wood samples were exposed to two different brown-rot fungi according to EN 113 standards. Brown-rot fungi, Coniophera puteana (Schumach.) P. Karst. (Mad-515) and Postia placenta (Fr.) Lars.& Lomb. (Mad-698-R) were used in this experiment. Both fungi were grown on 4,8% malt extract agar (MEA) medium. The media was steam sterilized at 120 oC for 20 mins before it was poured into each petri dish. After inoculation, petri dishes were kept at 23±2 oC and 65±5 % relative humidity until fungi completely covered the dishes. Following the test, the control samples’ oven-dried weights were determined. Each of them steam sterilized at 120 oC for 20mins. Eight controlled and treated samples were exposed to fungal testing. After the six weeks of exposure to both fungi, the weight loss of both control and treated samples was calculated from the dry weight before and after the treatment. 3. Result and Discussion 3.1 Retention Different concentrations of black liquor retentions were calculated on the uptake of liquid on treated wood samples, given in Table 1. As concentration increased, the retention amount also increased, parallel to liquid concentrations. Table 1 Retentions of different black liquor concentrations (gr/cm3) Concentrations %
Retentions
2.5
0.13
5
0.25
7.5
0.6
3.2 Mass losses Mass losses caused by C. puteana and P. placenta on wood samples treated with black liquor at 3 different concentration levels are shown in Table 2. The mass losses of untreated control samples exposed to C. puteana, and P. placenta were 29.5, and 26.3, respectively. When the mass losses of test and control specimens were investigated, C. puteana induced much higher mass loss. This indicates that C. puteana is more aggressive compared to the P. placenta fungi. When the concentration was increased, mass losses did not reduce. Wood protection is not always provided with the highest level retentions of preservatives (Palantini and Susco, 2004). Above 5% concentration, the black liquor showed an opposite effect against brown-rot fungus. The lowest mass loss was determined at 5% concentration.
2180
Sefa Durmaz et al. / Procedia - Social and Behavioral Sciences 195 (2015) 2177 – 2180 Table 2 Mass loss of samples Black Liquor
Coniophora
Concentration
puteana %
Poria placenta %
2.5%
0.6
0.4
5%
0.35
0.15
7.5%
2,9
2.2
Control
29.5
26.3
According to previous studies, Scots pine wood black liquor composes of lignin, hydroxyl carboxylic acids, acetic acid, formic acid, turpentine, resin and/or fatty acids, as well as miscellaneous products (Sjöström, 1983). It is thought that this mixture shows an inhibition against both brown-rot fungi. It can be stated that black liquor enhances the biological durability of Scots pine sapwood. 4. Conclusions The aim of this study is to develop an alternative preservative against copper-based chemicals. Black liquor is composed of several components formed by the degradation of wood. According to wood decay testing, mass loss of test and control samples showed that black liquor inhibits fungal activity and improves durability against these brown-rot fungi. In our next study, large scale timbers will be impregnated with black liquor. Following this its mechanical and physical properties will be investigated. References Alaoui-Sossé, B., Genet, P., Vinit-Dunand, F., Toussaint, M-L., Epron, D., Badot, P-M. (2004). Effect of copper on growth in cucumber plants (Cucumis sativus) and its relationships with carbohydrate accumulation and changes in ion contents. Plant Science, 166(5), 8-1213 Berglin, N., Berntsson, T. (1998). CHP in the pulp industry using black liquor gasification: thermodynamic analysis. Appl Therm Eng. 18(11), 61-947. Freeman, MH., McIntyre, CR. (2008). A comprehensive review of copper-based wood preservatives. Forest Prod J., 58(11), 6-27. Gierer, J. (1980). Chemical aspects of Kraft pulping. Wood Science and Technology.14(4), 241-66. Kartal, SN., Hwang, W-J., Imamura, Y. Sekine, Y. (2006). Effect of essential oil compounds and plant extracts on decay and termite resistance of wood. Holz als Roh- und Werkstoff, 64(6), 61-455 Mai, C., Kues, U., Militz, H. (2004). Biotechnology in the wood industry. Applied microbiology and biotechnology, 63(5), 94-477. Mohan, D., Shi, J., Nicholas, DD., Pittman, CU., Jr., Steele, PH., Cooper, JE. (2008). Fungicidal values of bio-oils and their lignin-rich fractions obtained from wood/bark fast pyrolysis. Chemosphere. 71(3), 65-456. Onuorah, EO. (2000). The wood preservative potentials of heartwood extracts of Milicia excelsa and Erythrophleum suaveolens. Bioresource Technology. 75(2), 3-171. Palantini, S., Susco, D., (2004). A new wood preservative based on heated oil treatment combined with triazole fungicides developed for aboveground conditions, International Biodeterioration & Biodegradation, 54, 337-342. Schmidt, O. (2006). Wood and Tree Fungi: Biology, Damage, Protection, and Use,7th ed., Springer, Berlin Sjöström, E. (1983). Wood Chemistry Fundamentals and Applications. Elsevier. Singh, T., Singh, AP. (2011). A review on natural products as wood protectant. Wood Science and Technology, 46(5), 70-851. Tascioglu, C., Yalcin, M., Sen, S., Akcay, C. (2013). Antifungal properties of some plant extracts used as wood preservatives. International Biodeterioration & Biodegradation, 85, 8-23. Vanassche, F., Clijsters, H. (1990). Effects of Metals on Enzyme-Activity in Plants. Plant Cell Environ, 13(3), 195-206. Yang, DQ. (2009). Potential utilization of plant and fungal extracts for wood protection. Forest Prod J., 59(4), 97-103. URL-1. http://www.epa.gov/oppad001/reregistration/cca/alternativestocca.htm . (13.02.2015).