Lignocellulosic Resources Research Articles

Characterizations and application potentials of the hemicelluloses in waste oil-tea camellia fruit shells from Southern China

Oil-tea camellia fruit shell (CFS) is a considerable waste lignocellulosic resource. The current treatment of these wastes are composting and burning. Burning may pose a threat to air and since CFS contains 5–14% saponins, the composting may lead to water foaming and toxicity. CFS contains a large amount of hemicelluloses, which has the potential to be extracted and valorized. The chemical structures of CFS hemicelluloses have not been extensively analyzed, which limits their application. In this study, hemicelluloses were extracted by dimethyl sulfoxide and alkali solution from eight species of CFS in Southern China. The detailed compositional and structural characteristics of the separated hemicellulose components were studied. The content of hemicelluloses in CFS ranges from 40% to 55%. The hemicelluloses consist of l-rhamnose, L-arabinose, L-fucose, D-xylose, D-mannose, D-glucose, D-galactose and D-glucuronic acid units, among which xylose is the major component. The existence of the sugars that are rare in lignocellulosic materials, i.e. fucose and rhamnose, are confirmed as the minor components. From 2D NMR analysis, the major chemical structures/types of CFS hemicelluloses are found to be L-arabinose-4-O-methyl-α-D-glucuronic acid-D-xylose and galacto-glucomannan. The application potentials of the CFS hemicelluloses in fine chemicals were evaluated.

Enhanced Mechanical Properties of Polyvinyl Chloride-Based Wood-Plastic Composites With Pretreated Corn Stalk.

Wood–plastic composites (WPCs) are a type of environmentally friendly materials widely used in daily life. This paper selected low-value biomass, corn stalk (CS), as the lignocellulosic resource for polyvinyl chloride (PVC)-based WPCs. To depict the relationship between lignocellulosic composition (cellulose, hemicellulose, and lignin) and mechanical performance of WPCs, pretreatments have been optimized to selective removal of lignin using an alkaline-EtOH stewing process and selective removal of hemicellulose using an acid stewing process. The αC sample, in which both lignin and hemicellulose were removed, shows the highest degree of crystallinity (72.60%) as estimated from X-ray diffraction analysis results and fibrous morphology with the highest aspect ratio as seen in scanning electron microscopy images. Compared with PVC/CS, PVC/αC gives a substantial increase in tensile strength and modulus by 37.21 and 21.66% and flexural strength and modulus by 29.98 and 34.88%, respectively. These improvements lie in the reinforcing effect of a fibrous structure and the improved interfacial compatibility as proven by scanning electron microscopy and dynamic mechanical analyzer results. Considering the extracted lignin and hemicellulose can be further developed to valuable biochemicals, the pretreatment to CS adds value to both WPC materials and biorefinery products.

Thermo-Chemical Conversion of Microwave Selectively Pre-Treated Biomass Blends

Possibilities of more efficient use of regional lignocellulosic resources (wood, wheat straw, peat) of different origin for an environmentally friendly energy production using selectively MW pre-treated blends of commercial wood or wheat straw pellets with raw peat pellets are studied. A hypothesis is proposed and tested that selective MW pre-treatment of wood or wheat straw pellets at the frequency 2.45 GHz and blending of MW pre-treated pellets with raw peat pellets can be used to enhance and control the thermo-chemical conversion of biomass blends. To test this hypothesis, a combined experimental study and mathematical modelling of the processes were performed. The thermo-chemical conversion of selectively activated blends was experimentally studied using a batch-size pilot device, which consists of a biomass gasifier and a combustor. To evaluate the effect of selective MW pre-treatment of biomass pellets on the thermo-chemical conversion of pre-treated blends, measurements of the kinetics of weight loss, yield of combustible volatiles, flame temperature, heat output of the device, and composition of emissions were made at different MW pre-treatment regimes of wheat straw and wood pellets and different mass fractions of pre-treated pellets in biomass blends. The developed novel 2D numerical model of thermo-chemical conversion of MW pre-treated straw confirmed that the pre-treatment of wheat straw pellets increases the generated heat and significantly affects the temperature distribution in the flame/bed zones. It was confirmed that MW pre-treatment leads to a faster thermal decomposition of biomass pellets, synergistically activating the non-treated parts of blends. The overall improved yield of combustible volatiles and their complete combustion provide a surplus of heat production by limiting the formation of GHG emissions, which allows promoting MW pre-treated biomass of different origin as efficient regional bioenergy resources for energy production.

Emerging trends and nanotechnology advances for sustainable biogas production from lignocellulosic waste biomass: A critical review

Biogas production is the most important requirement for substituting fossil fuel in an eco-friendly manner. Though several routes of renewable energy sources are available, biogas generation occupies an irreplaceable position due to huge lignocellulosic biomass availability. Hence, researchers worldwide are attempting on a large scale to develop low-cost and sustainable biogas production for use in transportation, electricity and heat generation. Studies have identified various lignocellulosic resources as raw materials for biogas production. In this context, the nanotechnological intervention and emerging strategies for sustainable biogas production have greater potential to meet the requirements in terms of cost and environmental safety. Biogas generation in oxygen-free digesting processes can be boosted by utilizing customized nanoparticles to dose ions. To maximize biogas generation, it is possible to use unstable nanoparticles, but they can be tailored to provide the ions in a regulated manner. Anaerobic conditions are ideal for nanoparticles dissolution and supply to anaerobic microbes responsible for the organic material breakdown, which is a job that is well-suited to them. However, there exists a large gap in providing up-to-date information on emerging nanotechnology research in biogas generation from enormous uncommitted lignocellulosic resources. To fulfill the lacuna, the present review critically elucidates the existing methods, nanotechnological intervention, emerging and advanced trends in biogas production to benefit society.

PHYSICAL, CHEMICAL AND MORPHOLOGICAL CHARACTERISTICS OF BAMBOO SPECIES GUADUA TRINII AND GUADUA ANGUSTIFOLIA AND THEIR POTENTIAL TO PRODUCE HIGH-VALUE PRODUCTS

High-value products can be obtained from non-traditional lignocellulosic resources, such as bamboo, taking full advantage of these materials through efficient, low-cost and low-pollution fractionation processes. This work aims to analyze the physical, chemical, and morphological differences between two bamboo species as a rapidly growing resource of great regional interest – Guadua trinii and Guadua angustifolia. Both samples were characterized in terms of basic density, morphological characteristics, and chemical composition. This work shows that G. trinii has a significantly denser woody structure, with a uniform density at the sampled culm height. The internal structure consists of a parenchyma matrix and vascular bundles composed of parenchyma cells and fiber bundles. G. angustifolia has significantly longer fibers. Chemical characterization showed differences between the carbohydrate and lignin contents. The results of this work are critical to know the potential of both bamboo species as a source of high-value products in the bamboo biorefinery framework.

Ammonia Fiber Expansion Combined with White Rot Fungi to Treat Lignocellulose for Cultivation of Mushrooms.

In order to improve the degradation efficiency of lignocellulose while increasing the yield of mushrooms, white rot fungi treatment (Pleurotus ostreatus, Pleurotus eryngii, and Pleurotus geesteranus) combined with ammonia fiber expansion was proposed as a method for treating lignocellulose (Pennisetum sinese, salix chips, and pine chips) for mushroom cultivation. Compared with treatment using either ammonia fiber expansion or white rot fungus, the combined treatment significantly improved lignocellulose degradation rate by 10–20% and reduced the time required significantly. Among them, P. geesteranus was the most effective bacterium for the combined treatment of lignocellulose. Ammonia fiber expansion-treated lignocellulose contributed to mycelial growth and increased the activity of three lignin hydrolase enzymes (laccase, manganese peroxidase, and lignin peroxidase) and mushroom yield. The mushroom yield was increased by 44.6%. The combined treatment method proposed in our study improves lignocellulose resource utilization and is therefore useful in the treatment of agricultural solid organic waste.

Bacterial xylan utilization regulons: systems for coupling depolymerization of methylglucuronoxylans with assimilation and metabolism.

Bioconversion of lignocellulosic resources offers an economically promising path to renewable energy. Technological challenges to achieving bioconversion include the development of cost-effective processes that render the cellulose and hemicellulose components of these resources to fermentable hexoses and pentoses. Natural bioprocessing of the hemicellulose fraction of lignocellulosic biomass requires depolymerization of methylglucuronoxylans. This requires secretion of endoxylanases that release xylooligosaccharides and aldouronates. Physiological, biochemical, and genetic studies with selected bacteria support a process in which a cell-anchored multimodular GH10 endoxylanase catalyzes release of the hydrolysis products, aldotetrauronate, xylotriose, and xylobiose, which are directly assimilated and metabolized. Gene clusters encoding intracellular enzymes, including α-glucuronidase, endoxylanase, β-xylosidase, ABC transporter proteins, and transcriptional regulators, are coordinately responsive to substrate induction or repression. The rapid rates of glucuronoxylan utilization and microbial growth, along with the absence of detectable products of depolymerization in the medium, indicate that assimilation and depolymerization are coupled processes. Genomic comparisons provide evidence that such systems occur in xylanolytic species in several genera, including Clostridium, Geobacillus, Paenibacillus, and Thermotoga. These systems offer promise, either in their native configurations or through gene transfer to other organisms, to develop biocatalysts for efficient production of fuels and chemicals from the hemicellulose fractions of lignocellulosic resources.

Structural properties and hydrolysability of recycled poplar residues (Populus L.): Effects of two-step acetic acid and sodium sulphite pre-treatment

Poplar trees rapidly yield wood and are therefore suitable as a biofuel feedstock; however, the quality of poplar is modest, and the profitability of poplar cultivation depends on the efficiency of the harvesting process. This study offers a simple and sustainable technique to harvest lignocellulosic resources from poplar for bioethanol production. The proposed two-step pretreatment method increased the surface lignin content and decreased the surface polysaccharide content. The cellulose content increased to 54.9% and the xylan content decreased to 6.7% at 5% AC. The cellulose yield of poplar residues (Populus L.) reached 65.5% by this two-step acetic acid (AC) and sodium sulphite (SS) treatment method. Two-step pretreatment using 5% AC and 4% SS obtained a recovery of nearly 80% of the total available fermentable sugar. The surface characterization showed a higher porosity in treated samples, which improved their hydrolysability. This method decreased the amount of lignin in plant biomass, making it applicable for further wood resource recovery or waste recycling for biorefinery purposes at very low costs.

Investigating the characteristics of cactus seeds by-product and their use as a new filler in phenol formaldehyde wood adhesive

The current study investigates the properties of cactus waste seeds (CWS) unexplored by-product as partial replacement of phenol formaldehyde (PF) adhesives in comparison to previously used olive stones (OS) for the production of wood composites. The chemical composition, structure, and thermal properties of CWS were studied for the first time to evaluate their suitability for incorporation into PF resins. The bonding strength, wood failure, and rheological properties of the formulated adhesives were investigated as well as the mechanical properties of the plywoods panels. The results showed that CWS could be considered as a new lignocellulosic resource, showing a higher amount of cellulose content (27%) compared to OS (15%). The crystallinity and thermal stability were higher in CWS, which was expected to improve the performance of the formulated adhesives positively. Moreover, the resins containing 10% and 15% of CWS and OS, respectively, showed comparable bonding strength and wood failure to that of a control PF resin. While plywood bonded with 10% of CWS:PF resin showed better mechanical performance in dry, cold, and 8h boiling water conditions than other adhesives, formaldehyde emission levels of bonded panels with both formulations were lower than those of a control PF. • Cactus waste seeds (CWS) were used to partially substitute PF-resins. • The chemical compositions of CWS are rich in lignin (37%) and cellulose (27%). • Crystallinity and thermal stability of CWS were higher compared to olive stones (OS). • PF-resin filled with CWS and OS showed good mechanical and rheological properties. • The optimal adhesives were practical for plywood application.

Production of β‐glucosidase by Aspergillus niger CDBB‐H‐175 on submerged fermentation

AbstractThe production of high‐activity β‐glucosidase at low cost is essential to increase the efficiency of cellulose hydrolysis, necessary for the economically feasible production of biofuels from the conversion of renewable lignocellulosic resources, specifically agricultural waste. In this work, the Aspergillus niger CDBB‐H‐175 strain was used for the production of extracellular β‐glucosidase. In the first stage of this work, the production of β‐glucosidase was carried out in a shake flask, using different carbon sources in order to evaluate the effect of the substrate on enzyme activity; in this way, it was determined that the best substrate is maltose, obtaining 2954 U/ml of β‐glucosidase activity at 31 days of culture. In the second stage, a laboratory‐scale study was done using two discontinuous bioreactor systems for submerged fermentation, stirred tank and airlift, using maltose, sucrose, and glucose as a carbon source. The results showed that β‐glucosidase with the highest enzymatic activity (3122 U/ml at 192 h of fermentation) was produced at uncontrolled pH conditions in an airlift bioreactor with maltose. In a third stage, using an airlift bioreactor with maltose, an orthogonal experimental design L4 with three factors was applied: pH, aeration, and maltose concentration. The aeration was of utmost importance to guarantee a better enzymatic expression, and acidification of the culture medium during the fermentation process was another necessary condition for a greater enzymatic production.

Production of ethyl levulinate fuel bioadditive from 5-hydroxymethylfurfural over sulfonic acid functionalized biochar catalysts

In this work, a series of novel -SO3H functionalized biochar materials were prepared and investigated for the first time as catalysts for the production of fuel additive ethyl levulinate (EL) from biomass-derived 5-hydroxymethylfurfural (HMF). The employed biochar was directly produced from vineyard pruning wastes by a simple hydrothermal treatment using water in subcritical conditions followed by 3 different one-step sulfonation processes. The effects of sulfonating agent, reaction temperature, reaction time and alcohol solvent were examined. Full HMF conversion together with outstanding EL yields (over 84%) were achieved at 130 °C and after 6 h over the biochar functionalized with the organosilane 2-(4-chlorosulphonylphenyl)ethyltrimetoxysilane (BioC-S3). Catalyst characterization suggested that the high acid strength (0.983 mmol H+·g−1) derived from the anchoring of arylsulfonic groups were responsible for the promotion of acid-driven etherification and ethanolysis steps. The BioC-S3 catalyst can be recycled without a significant loss of catalytic activity, indicating the stability of – SO3H organosilane group structure in the porous biochar. The obtained results offer a competitive alternative for the production of fuel additives, such as alkyl levulinates, using low-cost and easy-to-prepare biochar-based catalysts, all from lignocellulose resources, as an example to support a future exploitation of a potential biorefinery.

α-Cellulose-based films: effect of sodium lignosulfonate (SLS) incorporation on physicochemical and antibacterial performance

A homogeneous α-cellulose film was prepared by a regeneration method from ZnCl2/CaCl2/cellulose mixed system and was further combined with sodium lignosulfonate (SLS) via crosslinking through intermolecular hydrogen bonds and “bridge linkages”. The physicochemical and antibacterial performance of prepared films were investigated and results showed that the modified film exhibited stronger tensile strength, higher thermal stability, lower hydrophilic effect, better UV shielding as compared with the original one, and especially, better antibacterial ability derived from the presence of phenolic hydroxyl and sulfonate groups in SLS. This study proposed a simple and sustainable method for fabricating a multifunctional and environmentally friendly composite film using two main lignocellulose resources as raw materials.

Perspectives for Greening European Fossil-Fuel Infrastructures Through Use of Biomass: The Case of Liquid Biofuels Based on Lignocellulosic Resources

Given the importance of climate change it is vital to find a transition away from fossil fuels. The transition will include electrification of several sectors, for example road transport, but considering the strong dependency on carbon-based fuels and associated infrastructures, it is reasonable to assume that biomass-based hydrocarbon will play a key role to smoothen the transition away from fossil fuels. This study provides an analysis of direct and indirect technological options for liquid biofuels based on lignocellulosic resources in the context of greening European fossil-fuel infrastructures. Direct options are those which result in integration of biogenic feedstock in a fossil-based process and then co-processing in a downstream conventional unit or substituting a conventional part of the production chain of a liquid fuel by a bio-based one. Indirect options are those which pave the way for ramping-up biomass supply chain in the form of infrastructure and market. Examples of direct options in the focus of this study are biomass gasification for production of intermediates and biomass pyrolysis substituting fossil feedstock. Examples of indirect options are co-firing biomass in coal-fired power plants and integrating biomass gasification plants with district heating (DH) networks. Such options are important for establishing biomass supply chains and markets. This study also assesses the potential of biomass use in other industrial sectors not directly related with fossil-based fuel or energy production, such as the pulp and paper industry and the iron and steel industry. In this context, opportunities and barriers for both direct and indirect greening options are discussed, focusing mainly on technological and logistic aspects. It is highlighted that fossil-fuel infrastructures can act as drivers for the development of advanced biofuels production as they can reduce the initial risks, in terms of cost and technological maturity, offering the opportunity to increase gradually the demand for biomass, and develop the logistic infrastructure. It is, however, important to make sure that such biofuel production processes are part of a long-term strategy, which needs incentives to overcome current barriers and eventually phase out fossil infrastructures.

A strong, biodegradable and recyclable lignocellulosic bioplastic

Renewable and biodegradable materials derived from biomass are attractive candidates to replace non-biodegradable petrochemical plastics. However, the mechanical performance and wet stability of biomass are generally insufficient for practical applications. Herein, we report a facile in situ lignin regeneration strategy to synthesize a high-performance bioplastic from lignocellulosic resources (for example, wood). In this process, the porous matrix of natural wood is deconstructed to form a homogeneous cellulose–lignin slurry that features nanoscale entanglement and hydrogen bonding between the regenerated lignin and cellulose micro/nanofibrils. The resulting lignocellulosic bioplastic shows high mechanical strength, excellent water stability, ultraviolet-light resistance and improved thermal stability. Furthermore, the lignocellulosic bioplastic has a lower environmental impact as it can be easily recycled or safely biodegraded in the natural environment. This in situ lignin regeneration strategy involving only green and recyclable chemicals provides a promising route to producing strong, biodegradable and sustainable lignocellulosic bioplastic as a promising alternative to petrochemical plastics. There is growing interest in the development of biodegradable plastics from renewable resources. Here the authors report an in situ process involving only green chemicals to deconstruct natural wood, forming lignocellulosic bioplastics that are mechanically strong, stable against water and sustainable.

A Comparative Study of Maize and Miscanthus Regarding Cell-Wall Composition and Stem Anatomy for Conversion into Bioethanol and Polymer Composites

Due to an increasing demand for environmentally sustainable products, miscanthus and maize stover represent interesting lignocellulosic resources for conversion into biofuels and biomaterials. The overall purpose was to compare miscanthus and maize regarding cell-wall composition and stem anatomy for conversion into bioethanol and polymer composites using partial least squares regressions. For each of the two crops, six contrasted genotypes were cultivated in complete block design, and harvested. Internodes below the main cob for maize, and on the first aboveground internode for miscanthus, were analyzed for biochemistry and anatomy. Their digestibility was predicted using crop-specific near infrared calibrations, and the mechanical properties were evaluated in stem-based composites. On average, the internode cross-section of miscanthus anatomy was characterized by a thick rind (26.2%) and few but dense pith-bundles (3.5 nb/mm2), while cell-wall constituted 95.2% of the dry matter with high lignin (243.2 mg/g) and cellulose concentrations (439.7 mg/g). Maize internode-anatomy showed large cross-sections (397.5 mm2), pith with the presence of numerous bundles and non-lignified-pith fractions (22.3% of the section). Its cell-wall biochemistry displayed high concentrations of hemicelluloses, galactose, arabinose, xylose, and ferulic acid. Cell-wall, lignin, and cellulose concentrations were positively correlated with rind-fraction and pith-bundle-density, which explained strong mechanical properties as shown in miscanthus. Hemicelluloses, galactose, arabinose, and ferulic acid concentrations were positively correlated with pith fraction and stem cross-section, revealing high digestibility as shown in maize. This underlines interesting traits for further comparative genetic studies, as maize represents a good model for digestibility and miscanthus for composites.

Utilization of tea oil camellia (Camellia oleifera Abel.) shells as alternative raw materials for manufacturing particleboard

Tea oil camellia (Camellia oleifera Abel.) is a unique oil crop belongs to the genus Camellia of the Theaceae family with more than 4.4 million hectares in China to produce more than 2.4 million-ton fruit in 2019. There are about 1.8 million-ton by-products of tea oil camellia shell (TCOS). In view of the huge amount of TCOS produced, it is a severe concern to utilize the TCOS on a large scale instead of discarding it to cause various forms of environmental pollution and problems. Herein, we investigated the feasibility of using TCOS as a new lignocellulose resource instead of wood for particleboard production. The effective variables, including adhesive content, hot-pressing parameters (temperature, time, and pressure), and the ratio of shell particles to wood particles, were systematically investigated. Results showed the suitability of TOCS as a raw material for the particleboard industry. Accordingly, using 50 % of TOCS particles and 50 % commercial wood particles in the mat with 8% pMDI adhesive exhibited modulus of rupture (MOR) value of 13.4 N/mm2, modulus of elasticity (MOE) of 1840 N/mm2, and internal bonding strength (IB) of 1.22 N/mm2, qualified EN standard for particleboard type P2 (dry conditions), and its thickness swelling (TS) of 17 % met the minimum requirement of EN 312 for particleboard type P3.

Comparative Technical Process and Product Assessment of Catalytic and Thermal Pyrolysis of Lignocellulosic Biomass

Availability of sustainable transportation fuels in future hinges on the use of lignocellulosic resources for production of biofuels. The process of biomass pyrolysis can be used to convert solid biomass resources into liquid fuels. In this study, laboratory experiments and process simulations were combined to gain insight into the technical performance of catalytic and thermal pyrolysis processes. Waste pinewood was used as a feedstock for the processes. The pyrolysis took place at 500 °C and employs three different catalysts, in the case of the catalytic processes. A process model was developed with Aspen Plus and a wide range of representative components of bio-oil were used to model the properties of the bio-oil blend. The results of the process model calculations show that catalytic pyrolysis process produces bio-oil of superior quality. Different technical process scenarios were explored based on the properties of the bio-oil after separation of water-soluble components, with the intention of producing a blendable or stand-alone product. It was found that—depending on the bio-oil requirements—sufficient hydrogen can be made available from the aqueous fraction to further treat the organic fraction to the desired extent. The resulting organic fractions are suitable candidates for blending with conventional fuels. The analysis results are used to provide guidance for catalyst development.

Oil palm trunk biomass pretreatment with oxalic acid and its effect on enzymatic digestibility and fermentability

Abstract Oil palm trunk biomass (OPTB) is a promising lignocellulosic resource for bioconversion due to its abundant availability, low cost and high carbohydrates content. In the present work, oxalic acid was used to pretreat OPTB under different pretreatment conditions. We maintained the same pretreatment severity value by manipulating the reaction time over a range of oxalic acid concentrations. The impact of oxalic acid pretreatment was evaluated in terms of xylose recovery, enzymatic digestibility as well as fermentability of Actinobacillus succinogenes 130Z for the production of industrially valuable succinic acid. Our findings demonstrated that oxalic acid at 4% (w/v) concentration showed superior effectiveness in solubilising hemicellulose from OPTB, achieving 60.3% xylose recovery. During enzymatic hydrolysis, again, the OPTB pretreated with 4% (w/v) oxalic acid exhibited the highest enzymatic digestibility of 63.4% yielding 39.1 g of sugar per 100 g OPTB. However, it was found that high concentration of oxalic acid (3–4%, w/v) inhibited A. succinogenes 130Z fermentation. The results reported herein suggest that the pretreatment using low oxalic acid (1%, w/v), though requiring longer reaction time, is preferable for an improved succinic acid production from OPTB.

A novel core-shell Fe@Co nanoparticles uniformly modified graphite felt cathode (Fe@Co/GF) for efficient bio-electro-Fenton degradation of phenolic compounds

In this study, a core-shell Fe@Co nanoparticles uniformly modified graphite felt (Fe@Co/GF) was fabricated as the cathode by one-pot self-assembly strategy for the degradation of vanillic acid (VA), syringic acid (SA), and 4-hydroxybenzoic acid (HBA) in the Bio-Electro-Fenton (BEF) system. The Fe@Co/GF cathode showed dual advantages with excellent electrochemical performance and catalytic reactivity not only due to the high electron transfer efficiency but also the synergistic redox cycles between Fe and Co species, both of which significantly enhanced the in situ generation of H2O2 and hydroxyl radicals (OH) to 152.40 μmol/L and 138.48 μmol/L, respectively. In this case, the degradation rates of VA, SA, and HBA reached 100, 94.32, and 100%, respectively, within 22 h. Representatively, VA was degraded and ultimately mineralized via demethylation, decarboxylation and ring-opening reactions. This work provided a promising approach for eliminating typical recalcitrant organic pollutants generated by the pre-treatment of lignocellulose resources.

Natural durability of the Iranian domestic bamboo (Phyllostachys vivax) against fungal decay and its chemical protection with propiconazole

Bamboo culms are unique building materials for various kinds of structures. A wider acceptance of bamboo for structural uses, however, is often hindered by its propensity to biological degradation. The preservation of bamboo structures against biological hazards is an important requirement for utilizing this valuable lignocellulose resource. In this research, first, the chemical composition of bamboo tissue and its extractives, natural durability and the process of bamboo decay were investigated using two species of white rot fungi, i.e. Trametes versicolor and Xylaria polymorpha, two brown rot fungi, i.e. Coniophora puteana and Oligoporus placenta, and the soft rot fungus, Xylaria longipes. The samples were subjected to 4, 8, 12, and 16 weeks of exposure to fungi according to EN 113, and their weight loss (WL) and moisture content (MC) were studied. Secondly, aqueous suspension of 1% propiconazole was used as a fungicide to protect bamboo against different rotting fungi. The bamboo species Phyllostachys vivax was highly vulnerable to soft and white rots but showed a relatively higher durability against brown-rot fungi. However, it was not durable enough to be used without preservation and its biological resistance improved after treatment. Surprisingly, WL of bamboos decreased after leaching procedure, which could be related to the extraction of non-structural carbohydrates during leaching with water. A light microscopic study showed that different fungi preferably degrade different cells; white and soft rots mostly invaded ground parenchyma, while in brown rots, deterioration of phloem cells was more severe. In brief, bamboo needs to be treated before indoor and outdoor applications, and propiconazole as a cheap and environmentally friendly preservative can safely protect it against different fungal decay.