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    • 专利摘要:
    The present invention relates to an enzymatic process for conferring resistance to biotic agents on wood and derivatives thereof. The invention consists of the trapping of a water-soluble protector in the framework formed by kraft lignin on the surface of the wood and derivatives thanks to the action of laccase-type enzymes. It is recommended that the materials to be treated be subjected to a previous stage of conditioning. Subsequently, these are impregnated with a mixture formed by laccase solutions, water-soluble protector and kraft lignin by means of conventional industrial chemical impregnation methods (spraying, brushing, dipping, autoclaving, etc.) to finally dry them. As an advantage, it diminishes the leaching of the protector and the treated final products can be placed in scenarios of high humidification risk with a lower impact for the environment and human health. (Machine-translation by Google Translate, not legally binding)
    公开号:ES2639137A1
    申请号:ES201600325
    申请日:2016-04-25
    公开日:2017-10-25
    发明作者:Mª Del Carmen FERNÁNDEZ COSTAS；María Ángeles SANROMÁN BRAGA；Diego MOLDES MOREIRA
    申请人:Universidade de Vigo；
    IPC主号:
    专利说明:

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    In a particular embodiment, as enzymes to carry out the enzymatic process, enzymes of the type lacases, EC 1, 10, 2, enzymes belonging to the group of blue copper oxidases, capable of initiating a radical reaction in which substrates with redox potentials less than 1V (lignins, mainly in the present invention) will be oxidized with the subsequent reduction of molecular oxygen to water. Since the reactions take place in the aqueous phase, the oxygen itself dissolved in the solution will be responsible for promoting the enzymatic reaction. However, it has been reported that the contribution of external oxygen in reactions mediated by lacases reduces the incubation time (Ortner et al, 2015, Process Biochemistry 50, 1277-1283).
    In a particular embodiment, as water-soluble protectors, aqueous solutions containing metal compounds that can be trapped in the polymeric three-dimensional network of Kraft lignin can be employed. Preferably, aqueous solutions of metal salts that may contain arsenic, copper, zinc, boron or chromium and / or mixtures thereof will be used.
    In a particular embodiment, Kraft lignin from the black liquor obtained as a residue in the Kraft process will be used to trap the water-soluble protector. This liquor is alkaline pH and therefore contains soluble lignins, which can be obtained by precipitation thereof by acidification. The lignins used in the present procedure may have different origins. They can come directly from the industry or have been chemically modified. These are generated in large quantities in the paper industry and their use would thus lead to the revaluation of a waste. In addition, its highly degraded structure and phenolic concentration (Fernández-Costas et al., 2014, Biomass and Bioenergy: 63, 156-166) make it a very appropriate substrate for the application of this procedure.
    Kraft lignin may have a highly variable polymer size depending on its origin and, consequently, also a very variable solubility. Therefore, although it is recommended to work with high concentrations of Kraft lignin to achieve a greater framework that traps metal salts, in many cases, it will be the very solubility of Kraft lignin that marks the maximum possible concentration that can be used here. process.
    The aqueous mixture of the solutions of water-soluble protector, laccase and lignin Kraft is carried out prior to the impregnation step. In this way, the enzymatic reaction begins to act just before the contact with the wood. Once the mixture is added to the wood or derived products to be treated, the three-dimensional framework will begin to develop in which the active principles of the water-soluble protector will be trapped in the polymeric framework of Kraft lignin and, simultaneously, cross-linking will occur with the lignin itself present in the wood. The oxygen itself dissolved in the mixture will be responsible for the development of the reaction, however, as previously mentioned, it could be added externally in order to reduce the impregnation time.
    The impregnation develops at temperatures that cannot exceed 70 ° C, since at higher temperatures, the enzymatic activity of the lacquers will be already severely affected and, consequently, the crosslinking of the Kraft lignin and its binding to the wood.
    The operational conditions of the present procedure are mild and, in addition, compatible with conventional methods of applying chemical treatments of wood, both surface treatments (brushing, spraying, short immersion)
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    b) Previous preparation of the individual solutions of lignin Kraft, water-soluble protector and laccase.
    c) Impregnation of the wood comprising the simultaneous addition of the mixture of the solutions of lignin Kraft, water-soluble protector and laccase.
    d) Drying the impregnated samples.
    As a pre-impregnation step, the solutions of lignin Kraft, water-soluble protector and laccase will be prepared separately.
    The Kraft lignin solution will be prepared in a buffered solution in a pH range of 4-8 and with a concentration that can vary between 1 and 40% of referenced lignin based on dry wood or lignocellulosic starting material.
    In the case of the water-soluble protective solution, solutions containing metal salts that include arsenic, copper, zinc, boron or chromium and / or mixtures thereof will be used. Their concentration will depend on the treated wood, the degree of protection that is desired and the method used for impregnation (surface or deep). However, the treated samples must exceed, once the treatment is finished, the acceptability criteria of the European standard EN-599: 2009 + A1: 2013. In this way, the minimum effective amount of product in g / m2 for surface treatments and in kg / m3 for in-depth treatments would be identified.
    The impregnation takes place at room temperature or temperatures not exceeding 70 ° C and can be carried out by conventional surface modeologies such as brushing, spraying, short immersion; or in depth such as prolonged immersion, hot and cold immersion or autoclave treatments.
    The dose of lacasa varies depending on the type of treatment. In surface treatments such as brushing or spraying, enzymatic activities of 0.1-50 U / mL of reaction medium will be added. On the other hand, in deep treatments of wood and derived products, these will be impregnated immersed in the reaction medium and enzymatic activities of 1-100 U / g of dry wood or lignocellulosic material will be used. One unit of enzymatic activity (U) is defined as the amount of enzyme that oxidizes 1 μmol of 2,2'-azino-bis (3-ethylbenzothiazoline-6-sultanic acid (ABTS) per minute. Enzymatic activity is determined spectrophotometrically monitoring the oxidation of ABTS as a substrate (ε436 = 29300 M-1 cm-1) at pH 7 (phosphate buffer, 0.1 M) The laccase enzyme solution may be the commercial preparation itself, in case less activity is required, or for ease of work, dilutions of the commercial preparation can be worked in. In the latter case it will be necessary to dilute the enzyme in a buffer medium at pH 4-8. The Kraft lignin polymerization enzymatic reaction, as previously mentioned, it can be accelerated by the presence of oxygen, however, an external contribution is not strictly necessary for the present procedure.
    If the application is done by brushing usually requires 3 hands (allowing drying between them) to achieve penetrations similar to the spray. As for the brief immersion, this involves an immersion of the materials to be treated for a period that can last several seconds up to a maximum of 10 minutes. In these surface treatments maximum penetrations of 3 mm in wood are reached, therefore, for greater penetrations, deep treatments will be used. On the other hand, if in-depth treatments are used, impregnation times of at least 10 minutes will be used and that can reach up to 24 hours, depending on the volume of material to be treated and the impregnability of the wood species.
    With the intention of showing the present invention in an illustrative way but in no way limiting, the following practical example of the proposed invention is provided:
    First, the conditioning of the materials is carried out. Wood of Pinus sylvestris and Fagus sylvatica was barked and a section corresponding to the sapwood was selected, which was then dried until it reached a
    10 humidity of 18%. Finally, blocks of dimensions 30 x 10 x 5 mm3 were cut.
    The impregnation process was then carried out following a modified protocol of the European standard EN 113: 1997. The specimens with a humidity below 18% were introduced into the impregnation chamber and a vacuum of 0.7 kPa 15 was applied for 15 min. (Fig. 1.a). Next, the Kraft lignin solution mixture, the water-soluble protector solution and the enzymatic solution with the required concentration are prepared. 20% Kraft lignin solution was mixed with respect to dry wood weight, 25 mM CuCl2 solution and 50 U of enzyme per g of dry wood. The lignin Kraft solution has been maintained at pH 7 using a buffer
    0.1 M phosphate. Then, under vacuum, the above mixture was introduced and the impregnation was carried out for 10 minutes (Fig. 1.b). Finally, the specimens have been allowed to air dry at room temperature and for 24 hours to complete the treatment (Fig. 1.c).
    A batch of the treated samples has undergone accelerated aging according to the
    25 European standard EN-84: 1997 (but with 7 water changes) with the objective of evaluating copper leaching over time. This leaching study will demonstrate the effectiveness of the treatment in fixing the metal salt to the wood. The copper retention obtained in the P. sylvestris specimens for both treatments: enzymatic with Kraft lignin (proposed in the present invention) and conventional, are shown in the
    30 following table:
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    Slightly higher retentions have been found for conventional treatment,
    However, after washing the values are even lower than the treatment with the present procedure. Consequently, in conventional treatment, copper has been leached to a greater extent and has passed into the surrounding aqueous medium. Fig. 2 shows that the P. sylvestris woods treated by the present enzymatic process have, from the outset, a lower leaching of copper with respect to a
    40 conventional treatment with a copper metal salt. As advantages, a decrease in leaching is obtained and, therefore, a lower environmental impact of the treatment together with an increase in the useful life of the treated wood.
    In addition, wood specimens of P. sylvestris and F. sylvatica have been tested against
    45 to the fungal attack of Coniophora puteana and Trametes versicolor, respectively, for weeks and their mass loss has been analyzed to evaluate the efficacy of the treatment. Also, a control of untreated specimens has been carried out to ensure the virulence of the strains. The results obtained are reflected in the following table:
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    5
    The standard deviations have been indicated in brackets. The virulence control exceeds 20%, so the test is acceptable according to EN-113: 1997. Similar values obtained in terms of mass loss for the proposed treatment and aqueous copper treatment show the feasibility of the treatment. proposed and the
    10 bioavailability of copper for the fungus, despite its greater resistance to leachate.
    权利要求:
    Claims (1)
    [1]
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    同族专利:
    公开号 | 公开日
    ES2639137B1|2018-07-30|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US4752509A|1985-04-04|1988-06-21|Rune Simonson|Method for the impregnation of wood|
    WO1998016357A1|1996-10-11|1998-04-23|Novo Nordisk A/S|Process for impregnating solid wood and product obtainable by the process|
    EP1034903A1|1997-11-26|2000-09-13|Showa Denko Kabushiki Kaisha|Method for the treatment of wood with metallic treatment and wood treated by the method|
    WO2015168456A1|2014-05-02|2015-11-05|Arch Wood Protection, Inc.|Wood preservative composition|
    法律状态:
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    优先权:
    申请号 | 申请日 | 专利标题
    ES201600325A|ES2639137B1|2016-04-25|2016-04-25|Enzymatic procedure to confer wood and derived products resistance against agents of biotic origin|ES201600325A| ES2639137B1|2016-04-25|2016-04-25|Enzymatic procedure to confer wood and derived products resistance against agents of biotic origin|
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