Showing papers in "Bioresources in 2019"

Implications of Apparent Pseudo-Second-Order Adsorption Kinetics onto Cellulosic Materials: A Review

Abstract: The pseudo-second-order (PSO) kinetic model has become among the most popular ways to fit rate data for adsorption of metal ions, dyes, and other compounds from aqueous solution onto cellulose-based materials. This review first considers published evidence regarding the validity of the mechanistic assumptions underlying application of the PSO model to adsorption kinetics. A literal interpretation of the model requires an assumption that different adsorption sites on a solid substrate randomly collide with each other during a rate-limiting mechanistic step. Because of problems revealed by the literature regarding the usual assumptions associated with the PSO model, this review also considers how else to account for good fits of adsorption data to the PSO model. Studies have shown that adsorption behavior that fits the PSO model well often can be explained by diffusion-based mechanisms. Hypothetical data generated using the assumption of pseudo-first-order rate behavior has been shown to fit the PSO model very well. In light of published evidence, adsorption kinetics of cellulosic materials is expected to mainly depend on diffusion-limited processes, as affected by heterogeneous distributions of pore sizes and continual partitioning of solute species between a dissolved state and a fixed state of adsorption.

Lignin recovery from spent alkaline pulping liquors using acidification, membrane separation, and related processing steps : A Review

Abstract: The separation of lignin from the black liquor generated during alkaline pulping is reviewed in this article with an emphasis on chemistry. Based on published accounts, the precipitation of lignin from spent pulping liquor by addition of acids can be understood based on dissociation equilibria of weak acid groups, which affects the solubility behavior of lignin-related chemical species. Solubility issues also govern lignin separation technologies based on ultrafiltration membranes; reduction in membrane permeability is often affected by conditions leading to decreased solubility of lignin decomposition products and the presence of colloidal matter. Advances in understanding of such phenomena have potential to enable higher-value uses of black liquor components, including biorefinery options, alternative ways to recover the chemicals used to cook pulp, and debottlenecking of kraft recovery processes.

Biorefinery Review: Wide-Reaching Products Through Kraft Lignin

Abstract: This review details the structure of lignin and curates information on the characteristics that this polymer must have for each specific use. Lignin is a by-product of the pulp and paper industry and the second most abundant biopolymer after cellulose. Approximately 50 million tons of lignin are produced worldwide annually, of which 98% to 99% is incinerated to produce steam, process energy. Just 1% to 2% of the lignin, derived from the sulfite pulp industry, is used in chemical conversion to produce lignosulfonates. Biorefining is a promising approach to promote the wider use of kraft lignin. However, using kraft lignin to produce high value-added products is a great challenge, due to its complex structure, low reactivity, and low solubility, which are factors that limit the lignin’s large-scale use in biorefineries. Recent studies show that kraft lignin can be used as lignosulfonates and dispersants, technical carbons, transportation fuels, bioplastics, and adhesives, but some technological hurdles must be overcome and several industrial tests must be developed to make these uses viable.

Bio-based Polymers for Sustainable Packaging and Biobarriers: A Critical Review

Abstract: Barrier materials have an important role in various packaging applications, especially considering the requirements associated with protection and shelf life. Most barrier materials used in today’s industry are either manufactured from oil resources or metals. Driven by the increase in environmental awareness, access to oil resources as well as legislation, new and environmentally benign alternatives are at the center stage of scientific and industrial interest. This article covers the use of wood-derived polymers and those produced from microorganisms, which display remarkable barrier properties. Wood-based products have received great attention for their air/oxygen resistance. As far as their properties, microorganism-derived biopolymers are comparable to conventional oil-based thermoplastics, but their cost may still be an issue. Both, wood and microorganism-derived biopolymers are challenged when moisture, grease and oxygen resistance are simultaneously required. Hence, multilayer structures and composites are needed to fulfill the most demanding requirements of packaging materials. Here we offer a review of these topics together with a discussion of their prospects.

Natural Bio-Based Products for Wood Coating and Protection against Degradation: A Review

Abstract: Preservation of wood structures against degradation represents an old, and however, a new challenge. Wood, as a natural hybrid composite material, represents a versatile and widely exploited renewable resource for indoor and outdoor applications. Its constitutive biopolymers are subjected to intense and progressive oxidative degradation processes under environmental conditions of exposure, affecting wood's native durability and generating significant structural and color changes, along with progressive diminution of its resistance against biological agents. One effective way to prevent wood degradation is to apply coating protective layers by chemical modification of the surface. In this context, increasing interest for improving wood coatings behavior under exposure to outdoor applications, when these are able to prevent or limit to a large extent the deleterious effects of environmental factors upon their performance, justifies enhanced research efforts to provide new effective solutions for sustainable wood protection. Recent trends in this area include use of bio-based natural products – extractives, oils, waxes, resins, biopolymers, biological control agents – for which the main classification criterion is represented by the type of protection provided, considering the large available variety of such formulations. The present paper focuses on the most recent literature data with significant assessment of specific topics related to these issues.

Development of Seaweed-based Bamboo Microcrystalline Cellulose Films Intended for Sustainable Food Packaging Applications

Abstract: Seaweed bio-composite films with different proportion of Lemang and Semantan bamboo microcrystalline cellulose (MCC) were fabricated via solvent casting. The seaweed/MCC composite films were flexible, transparent, and slightly yellow. The MCC particles further enhanced mechanical properties and opacity of films. The thermal stability of seaweed films was moderately improved upon addition of bamboo MCC particles. Bamboo MCC was found to be comparable to commercial MCC in reducing the water vapor permeability (WVP), water solubility (WS), and moisture absorption capacity (MSC) of seaweed films. The tensile strength (TS) of seaweed films was increased by 20 to 23% with addition of up to 5% MCC particles. In addition, bamboo MCC efficiently reduced the WVP of seaweed films comparable to commercial MCC particles. The WS of seaweed films was decreased by 10 to 19% with addition of 1% MCC particles loading. Lemang bamboo MCC (SB-MCC) was remarkably reduced the moisture absorption capacity (MAC) of films up to 25% with inclusion of only 1% MCC. Morphological analysis via Scanning Electron Microscopy (SEM) confirmed that there was homogeneous dispersion of MCC particles in the films. MCC particles improved the mechanical, thermal, and optical properties of seaweed films making them more suitable for food packaging applications.

Physicochemical Analysis of Apple and Grape Pomaces

Abstract: This study details a comprehensive analysis of apple and grape pomaces that were generated in the course of juice and wine production, respectively. An extensive physicochemical analysis of these pomaces was performed to determine the elemental composition, ash content, sugar profile, and lignocellulose content. Scanning electron microscopy (SEM) images were taken to examine the morphology of the pomaces. Thermal stability was also examined using thermogravimetric analysis (TGA). Infrared spectroscopy was performed to observe the functional groups on the surfaces of the pomace samples. Grape pomace (GP) had better thermal stability than apple pomace (AP), but washing AP improved its thermal stability. The results from this study provide crucial information for various value-added applications of both apple and grape pomaces, especially for applications which are temperature-dependent. The diversion of these materials from waste back into the economic stream can alleviate their environmental burden and promote sustainable product development.

Fruit Waste Valorization for Biodegradable Biocomposite Applications: A Review

Abstract: Currently, food waste is a major concern for companies, governments, and consumers. One of the largest sources of food waste occurs during industrial processing, where substantial by-products are generated. Fruit processing creates a lot of these by-products, from undesirable or “ugly fruit,” to the skins, seeds, and fleshy parts of the fruits. These by-products compose up to 30% of the initial mass of fruit processed. Millions of tons of fruit wastes are generated globally from spoilage and industrial by-products, so it is essential to find alternative uses for fruit wastes to increase their value. This goal can be accomplished by processing fruit waste into fillers and incorporating them into polymeric materials. This review summarizes recent developments in technologies to incorporate fruit wastes from sources such as grape, apple, olive, banana, coconut, pineapple, and others into polymer matrices to create green composites or films. Various surface treatments of biofillers/fibers are also discussed; these treatments increase the adhesion and applicability of the fillers with various bioplastics. Lastly, a comprehensive review of sustainable and biodegradable biocomposites is presented.

Extraction, Chemical Composition, and Characterization of Potential Lignocellulosic Biomasses and Polymers from Corn Plant Parts

Abstract: Corn is a plant that can be used as a potential source of biomass for various biomaterial applications. Thermoplastic corn starch and corn hull, husk, and stalk fibers were extracted from different corn plant parts. The chemical composition, physical properties, thermal stability, crystallinity index, and surface morphology of the extracted samples were characterized on a powder basis. The corn husk and corn starch revealed an excellent combination of properties. Corn husk provided the highest cellulose content as well as the most favorable surface morphology. Corn starch revealed acceptable amylose content and tolerable thermal stability. The cellulose and starch demonstrated an excellent correlation between the function and structure of biomolecules. Hence, both corn starch and husk have potential for use in many applications of the biomaterial.

Flexural Behavior of Sprayed Lightweight Composite Mortar-original Bamboo Composite Beams: Experimental Study

Abstract: To study the flexural behavior of a composite beam, original single and double bamboo beams (SBBs and DBBs, respectively) and sprayed lightweight composite mortar-original bamboo composite beams (SCBs and DCBs) were designed and subjected to a four-point bending test based on the moisture content of the original bamboo. The failure modes, bearing capacity, and initial flexural rigidity of all of the beams were analyzed. Also, the strengthening effect of the lightweight composite mortar on the flexural behavior was studied. The results showed that a higher moisture content in the bamboo degraded the anti-slip property of the bond interface between the lightweight composite mortar and bamboo. The moisture content of the bamboo should be kept at approximately 20% before spraying. The initial flexural rigidity and bearing capacity of the DBBs were approximately 2.5 times and twice that of the SBBs, respectively. The initial flexural rigidities of the SCBs and DCBs were approximately 3.8 and 5.7 times that of the SBBs and DBBs, respectively. The ultimate load bearing capacity of the composite beams was approximately 1.5 times that of the original bamboo beams. It was shown that the lightweight composite mortar had a remarkable strengthening effect on the flexural behavior of the original bamboo.

Natural Polymers as Alternative Adsorbents and Treatment Agents for Water Remediation

Abstract: This review examines the roles of different natural polymers, composites, and nanoengineered materials that have been studied in the last 10 years for their use in water treatment. As water quality is a global concern, the use of natural and sustainable materials is fundamental to obtain high value products that can remediate water systems without generating other pollution sources or require extra energy inputs or high side costs. Filtration systems often can provide an ideal alternative to conventional water treatment. Herein the attention is focused on polysaccharides, as these can be easily obtained from green processes and can be sourced from what nowadays are considered as agricultural waste. The inherent variety of functional groups that they have provides a better interaction with certain types of pollutants. Thus, biomaterials have been harnessed to generate filtration systems and other water treatment options.

Changes in the Physicochemical Characteristics of Peanut Straw Biochar after Freeze-Thaw and Dry-Wet Aging Treatments of the Biomass

Abstract: Effects of aging after pyrolysis were tested relative to the physicochemical characteristics of peanut straw biochar. Biochar was prepared at pyrolysis temperatures of 350 °C, 500 °C, and 650 °C; then, it was freeze-thawed and dry-wet aged. The physicochemical characteristics of the fresh and aged biochar were analyzed. The results showed that the pyrolysis temperature, ambient temperature, and humidity affected the physicochemical characteristics of the biochar. With the increase of pyrolysis temperature, the yield and surface acidic functional groups of the fresh biochar decreased, whereas the ash content, C content, pH, specific surface area, and mesoporous volume of the fresh biochar increased. The aging treatment increased the acidic functional groups content in the biochar and reduced the aromatic functional groups content, which decreased the pH value of the biochar. The aging treatment increased the specific surface area and pore volume of the biochar, and the effect of freeze-thaw aging was greater than that of dry-wet aging. The aging treatment also destroyed the complete shape of the fresh biochar, and reduced its stability. After the aging treatment, the C content of the biochar decreased, whereas the O content increased, due to oxidation of the biochar.

Review of Electrically Conductive Composites and Films Containing Cellulosic Fibers or Nanocellulose

Abstract: Strategic combinations of cellulosic materials with electrically conductive polymers or nanoconductors offer important potential advantages for technological advances, light-weight inexpensive products, applications of novel form factors, and more eco-friendly alternatives to certain forms of smart packaging and electronics. This review of the literature focuses on how such electrically conductive composite systems work, the roles that cellulosic materials can provide in such structures, processes by which electrically-conductive cellulose-based composites and films can be manufactured, and various potential applications that have been demonstrated. Several advantages of cellulose, such as ease of fabrication, compatibility with conductive agents, and sustainability, allow its integration with conductive agents in making conductive composites. Applications of electrically conducting cellulose-based composites for strain sensors, energy storage, solar cells, electrodes, supercapacitors, and smart packaging are discussed.

Analytical Staining of Cellulosic Materials: A Review

Abstract: Numerous dyes and fluorescent compounds, as reported in the literature, exhibit specificity in the staining of materials associated with lignocellulosic fibers and their chemical components, including cellulose, hemicellulose, and lignin. Such effects long have provided analysts with convenient ways to identify cellulosic fiber types, products of different pulping methods, degrees of mechanical refining, estimates of accessibility to enzymes, and localization of chemical components within microscopic sections of cellulosic material. Analytical staining procedures allow for the facile estimation or quantification using simple methods such as light microscopy or UV-vis spectroscopy. More recent developments related to confocal laser micrometry, using fluorescent probes, has opened new dimensions in staining technology. The present review seeks to answer whether the affinity of certain colored compounds to certain cellulose-related domains can improve our understanding of those stained materials – either in terms of their fine-scale porous structure or their ability to accommodate certain colored compounds having suitable solubility characteristics. It is proposed here that successful staining ought to be viewed as being a three-dimensional phenomenon that depends on both the physical dimensions of the colored compounds and also on functional groups that influence their interactions with different components of lignocellulosic materials. Published information about the mechanisms of staining action as well as characteristics of different stain types is reviewed.

Forest Residues as a Renewable Source of Energy: Elemental Composition and Physical Properties

Abstract: Forest residues are a potentially important source of renewable energy. They are generated as a byproduct of timber harvesting around the world. To optimize the utilization of such biomass, one must know its physical and chemical properties. This paper presents an analysis of comminuted forest residues from Pinus sylvestris L. They were classified into four size fractions for which three density parameters were established pursuant to relevant standards. The mean bulk density of the fractions amounted to 110 to 190 kg/m3, apparent density 725 to 908 kg/m3, and specific density 1111 to 1350 kg/m3. The findings were compared to the results of previous research on other forms of forest biomass. The measured apparent-to-specific density conversion coefficient was β = 0.64. The elementary composition of forest residues measured in this work differed from that of other biomass types described in literature. In terms of carbon, nitrogen, sulfur, oxygen, and ash content, statistical analysis showed that the two compared types of biomass (forest residues and energy wood chips) formed two separate homogeneous groups, while both of these materials constituted one homogeneous group in the case of hydrogen content. The calorific value of the forest residues was 15.78 ± 0.39 MJ/kg.

Activity of Plant Extracts/Essential Oils Against Three Plant Pathogenic Fungi and Mosquito Larvae: GC/MS Analysis of Bioactive Compounds

Abstract: Certain natural products extracted from different parts of medicinal and aromatic plants were examined for their antifungal activity against three plant pathogenic fungi, Fusarium oxysporum, Rhizoctonia solani, and Alternaria solani, and insecticidal activity against mosquito larvae (Culex pipiens). Acetone extract of Tectona grandis showed the highest antifungal activity against R. solani and A. solani with EC50 values of 118 and 294 μg/mL, respectively. The highest larvicidal activity was displayed by the essential oils of Ocimum basilicum and Eucalyptus gomphocephala with LC50 value of 22, and 30 mg/L, respectively. By gas chromatography–mass spectrometry (GC/MS) analysis 3-allylguaiacol (65.8%) and eugenol acetate (46.6%) were the main compounds in Syzygium aromaticum methanolic extract and essential oil, respectively. The main compound in T. grandis acetone extract was cyclohexylpentyl oxalate (8.7%); its water extract contained (E)-4,4-dimethyl-2-pentene (51.1%); E. gomphocephala branch oil contained p-cymene (28.8%); Euphorbia paralias leaf extract contained 1βH-romneine (26.3%); the seed extract contained α-linolenic acid, TMS (15.2%); Punica granatum extract contained furfural (32.1%); and O. basilicum essential oil contained estragole (65.9%). Thus, extracts from the tested plants can be used as natural biofungicides to manage diseases caused by F. oxysporum, R. solani, and A. solani. Additionally, these extracts show potential la rvicide activities against mosquito larvae.

Degradation Mechanisms of Curaua, Hemp, and Sisal Fibers Exposed to Elevated Temperatures

Abstract: The influence of elevated temperatures on mechanical behavior was studied for curaua, hemp, and sisal natural fibers. Tensile tests were performed on fibers heated at 100 °C, 150 °C, and 200 °C for 24 h, and reference samples were maintained without thermal treatment for comparisons. The cross sectional area of the fibers was measured using a scanning electron microscope (SEM), and the image analysis was performed using the open source software Fiji/ImageJ. These data allowed the computation of the tensile stresses and the correlation of the fiber morphology with its macro-mechanical behavior. The thermal degradation behavior of the natural fibers was measured via thermo-gravimetric analysis (TGA) and X-ray diffraction (XRD). The morphological and mechanical characteristics were described and discussed on a microstructural basis. The results showed that the loss of moisture leads to a significant increase in tensile strength before reaching the limits of the degradation range.

Enhanced Amount and Quality of Alginate-like Exopolysaccharides in Aerobic Granular Sludge for the Treatment of Salty Wastewater

Abstract: Osmotic pressure provided by salty wastewaters is an important influencing factor for alginate-like exopolysaccharides (ALE) in aerobic granular sludge (AGS). Therefore, research on the influence of salinity (NaCl 0 R1, 10 g/L R2, 30 g/L R3) on AGS and its ALE formation was conducted. A salinity of 1% induced larger particle size with smooth spheroidal shape and enhanced granular strength in R2. The TOC and ammonia removal were unaffected in both R2 and R3, but the P removal was greatly enhanced. ALE was much enriched at moderate salinity (1% NaCl). The amount of ALE reached 49.8 mg/g VSS at 140 d in R2, which was much higher than in R1 (26.8 mg/g VSS) and R3 (28.9 mg/g VSS), possibly due to the activation of gene algC expression in AGS of R2. ALE also showed the largest GG block fractionation and MW in R2, which indicated the greatest enhancement of mechanical properties. Moreover, enrichment of glucosamine, lipid content, and octadecanamide derivative in ALE of R2 endowed it with medicinal potential, stronger water-barrier property, and reduction of the products’ friction coefficients, respectively. Therefore, AGS based on ALE is a potential technology for treatment of salty wastewater.

Anatomical, Physical, and Mechanical Properties of Thirteen Malaysian Bamboo species

Abstract: The anatomical, physical, and mechanical properties of 13 Malaysian bamboos and the trend of these properties along the bamboo culms’ height were examined. The results showed that these properties varied between the 13 species and they were also affected by the culm height. From the results obtained, the fibre morphology, as well as radial, longitudinal, and tangential shrinkage from green to oven-dry decreased from the basal to the top of the bamboo culm. In contrast, the opposite trend was observed for the density, modulus of rupture, modulus of elasticity, and percentage of the vascular bundle. The potential usage of 13 bamboo species is also considered.

Biosorption of heavy metals by lignocellulosic biomass and chemical analysis

Abstract: Many types of lignocellulosic biomass show effective binding of toxic heavy metals from industrial and environmental effluents. Biosorption is an emerging option for conventional methods to remove heavy metals, some of them with even better efficiencies compared to conventional methods. Raw material for biosorption is typically low-cost and easily available, including agricultural waste or forest residues such as sawdust, bark, or needles. This review concentrates on the accumulation of heavy metals by lignocellulosic biosorbents. Thus far, biosorption has not been economically feasible on a large scale and needs further development for profitability. Industrial-scale wood-based biosorbent applications are especially still lacking. Moreover, due to legislative demands, there is an increasing need for accurate and reliable analytical methods for metal analysis of environmental and industrial effluents. In the future, biosorption processes are likely to become common, and the requirement for environmental monitoring will increase due to ever restricting regulations. This emphasizes not only the need for the development of feasible process solutions, but also a requirement for accurate analytical methods.

Color and Chemical Changes in Teak (Tectona grandis L. f.) and Meranti (Shorea spp.) Wood after Thermal Treatment

Abstract: This paper studied the effect of thermal treatment (160 °C, 180 °C, and 210 °C), based on ThermoWood® principle, on the color and chemical properties of teak (Tectona grandis L. f.) and meranti (Shorea spp.) wood. The color of the wood was determined using the CIE L*a*b* system before and after the thermal treatment and was evaluated according to the total color change. The chemical changes were evaluated by wet chemical methods. The lightness of the wood was most affected during treatment. Meranti wood became darker (46.1%) compared with the teak wood (41.8%). The red-green and yellow-blue coordinates were higher in the teak wood, and their values decreased as the thermal treatment temperature increased in both wood species compared with untreated wood. The color change was higher in the meranti wood, and it increased steadily with increasing temperature. The extractives, cellulose, and lignin percentage contents increased in both wood species; however, the highest treatment temperature of 210 °C decreased the lignin in the meranti wood. The least stable component in both wood species was the hemicellulose. The hemicellulose content in the teak wood decreased by 67.7%, while it decreased by up to 80.5% in the meranti wood.

Comparison of wood and non-wood market pulps for tissue paper application.

Abstract: A comparison among ten market pulps at a laboratory scale using uncreped tissue handsheets was performed to study the performance of wood and non-wood pulps for tissue manufacturing, evaluate what fiber features are desired for a specific tissue property, and determine how non-wood pulps can be used to replace or complement wood pulps in tissue products. A characterization of the fiber morphology and handsheet properties (softness, water absorbency, and strength) was performed at different mechanical refining levels. The results showed that the fiber morphology had a major impact on tissue properties. Market pulps with a combination of long fibers, high coarseness, and low fines content can provide superior bulk and water absorbency. Short fibers with thin cell walls and low fines content can impart superior softness. Bleached bamboo soda pulp can replace hardwood and softwood pulps to provide an excellent combination of water absorbency and strength. Bleached bamboo soda pulp can also replace Northern bleached softwood kraft (NBSK) pulp to impart strength without sacrificing softness. Bleached and semi-bleached wheat straw soda pulps presented a similar combination of softness and strength as Southern bleached hardwood kraft (SBHK) pulp. The wheat straw pulps can be used to replace deinked pulp (DIP) pulp to impart intermediate levels of water absorbency and strength.

Response Surface Optimisation of Enzymatically Hydrolysed and Dilute Acid Pretreated Oil Palm Trunk Bagasse for Succinic Acid Production

Abstract: The exploitation of agroindustrial lignocellulose, such as oil palm trunk bagasse (OPTB), as a raw material in the production of succinic acid (SA) may serve as an effective strategy to propel the bio-based industry. This study aimed to optimise the recovery of fermentable sugar, i.e., glucose, from enzymatic hydrolysis of the dilute acid pretreated OPTB (DA-OPTB). The dilute acid pretreatment used in this study was able to remove 59.5% of hemicellulose and 13.3% of lignin. Response surface methodology (RSM) based on central composite design (CCD) was then applied to investigate four independent variables – enzyme loading (10 to 50 U/g), agitation speed (50 to 250 rpm), reaction time (0 to 96 h), and surfactant concentration (0.025 to 0.125%, v/v). The experimental glucose concentration of 21.7 g/L was in good agreement with the RSM-predicted value of 20.5 g/L. Among the parameters investigated, supplementation of a surfactant during enzymatic hydrolysis was significant in influencing glucose recovery, while the extent of the agitation speed was the least influential. The maximum recovered glucose was estimated at 217 g per kg of raw OPTB, with 7.3 g/L of SA attainable from the fermented DA-OPTB hydrolysate using Actinobacillus succinogenes 130Z. The results demonstrated that OPTB can be practically utilised in the economical production of high value-added SA.

A Comparative Study on the Mechanical, Thermal, and Water Barrier Properties of PLA Nanocomposite Films Prepared with Bacterial Nanocellulose and Cellulose Nanofibrils

Abstract: Mechanical, thermal, and water barrier properties of poly(lactic acid) (PLA) film reinforced with cellulose nanofibrils (CNF) and bacterial nanocellulose (BNC) were studied and compared. The in-situ formation of sodium carbonate (Na2CO3) on the BNC surface may aid in reducing the interchain hydrogen bonding and agglomeration of BNC fibers. At optimum loading, both CNF/PLA and BNC/PLA nanocomposite films exhibited higher tensile strength and Young’s modulus than the neat PLA without sacrificing its toughness. The BNC/PLA nanocomposite films displayed lower water vapor transmission rate (WVTR) as compared to neat PLA and CNF/PLA films at 0.5 and 1.0 wt%. BNC was found to induce imperfect crystal structures and exhibited higher overall crystallinity than neat PLA and CNF/PLA composites at 0.5 wt%. The BNC/PLA showed higher mechanical properties than CNF/PLA nanocomposites. Nanocellulose derived from plants and bacteria could provide promising solutions to develop high performance biobased-nanocomposites film for packaging application.

Effect of Steam Explosion on the Structural Modification of Rice Straw for Enhanced Biodegradation and Biogas Production

Abstract: The goal of this study was to develop an operational steam explosion pretreatment for effective modification of rice straw chemical structure in order to improve its biodegradability and methane yi ...

Acoustic Absorption and Thermal Insulation of Wood Panels: Influence of Porosity

Abstract: The development of materials that offer environmental comfort inside buildings, through adequate thermal and acoustic behavior, has been as relevant as the search for raw materials of renewable origin. In this context, this study produced and characterized panels made with Pinus sp. waste materials, which were treated with a copper chrome boric oxide preservative and a castor-oil based polyurethane resin. The physical and mechanical properties of the panels were evaluated according to the ABNT NBR 14810 standard (2013). The panel porosity was investigated by scanning electron microscopy (SEM) and mercury intrusion porosimetry techniques. The sound absorption was analyzed by a reverberation chamber and thermal conductivity by the modified fractionated column method. Samples with a higher pressing pressure (4 MPa) during the manufacturing presented lower thickness swelling and higher mechanical properties in static bending. Panels made with a lower press pressure (2.5 MPa) resulted in a higher porosity volume (55.7%). The more highly porous panels were more acoustically efficient, with a sound absorption coefficient close to 0.8 at 3.2 kHz, and they had a better thermal conductivity performance.The potential of these panels for application where sound absorption and thermal insulation are prioritized is thus observed.

Techno-Economic Analysis for Manufacturing Cross-Laminated Timber

Abstract: Cross-laminated timber (CLT) is a bio-based building material that enables rapid construction and buildings with low embodied energy. Despite its comparative maturity in European markets, relatively little information regarding process design and economics for the manufacture of cross-laminated timber is available in the literature. Two techno-economic analyses were conducted to quantify the mill-gate cost of cross-laminated timber. The cross-laminated timber manufacturing process was described, and costs were analyzed for two facility scales. Cross-laminated timber produced at the large-scale facility using lumber priced at an average value for the northwest United States has a minimum selling price of $536/m3. Sensitivity analyses were used to define the impact of plant size, asset utilization, lumber price, plant capital cost, material waste, and other variables on minimum selling price. The cost of cross laminated timber rises quickly when a facility is not fully utilized. The second-ranking cost controlling variable is lumber price, while energy prices have minimal influence. The price of cross laminated timber can be optimized by locating a facility near low-cost lumber. The lowest-price region analyzed was the southeast United States using Southern Pine, which reduced the cost of cross laminated timber to $518/m3.

Improving Thermal and Mechanical Properties of Injection Moulded Kenaf Fibre-reinforced Polyhydroxy-butyrate Composites through Fibre Surface Treatment

Abstract: Ecofriendly biodegradable composites were developed to mitigate the impact they have on the environment. Composites made from completely biodegradable materials were prepared using kenaf fibres and polyhydroxybutyrate (PHB). The composites were mixed using a twin screw extruder and injection moulded into dumbbell-shaped specimens. The composites were subjected to thermal analysis via differential scanning calorimetry (DSC) and mechanical testing (tensile and flexural tests). The addition of alkali-treated kenaf fibre reduced the crystallinity of PHB (up to 6% reduction), making it more ductile. The rheological behaviour of PHB was modified with the addition of kenaf fibres. Additionally, the flexural modulus was improved by up to 11% with the addition of kenaf fibres, for both the treated and untreated kenaf fibres. However, it was also observed that to improve fibre matrix adhesion, an alkali treatment alone is insufficient, as shown by the 16% reduction of tensile strength in composites with 20% fibre loading.

Flour Fillers with Urea-Formaldehyde Resin in Plywood

Abstract: Various flours were added as fillers for urea-formaldehyde (UF) resin, and effects on the rheological behavior and the curing properties of the resin were evaluated. The plywood properties such as bonding quality, bending strength, modulus of elasticity, and formaldehyde-release were tested. Five types of flours were used, i.e., rye flour, hemp flour, coconut flour, rice flour, and pumpkin flour. The type of flour had a major influence on the properties of resin mixture such as gel time, solid content, and viscosity. The use of rye and pumpkin flour resulted in a longer gelling time, and the adhesive mixture filled with rice flour did not attain the desired viscosity value needed for the production of plywood. The best mechanical properties and bonding quality were achieved by addition of pumpkin flour. However, the bonding quality of plywood glued with an adhesive filled with every other flour retained good values exceeding 1 N/mm2 as required by the standard EN 314-2 (1993). The use of hemp flour as a filler for UF resin led to a substantial decrease of free formaldehyde content.

Purification and Characterisation of Thermostable α-Amylases from Microbial Sources

Abstract: α-Amylases (E.C 3.2.1.1) hydrolyse starch into smaller moieties such as maltose and glucose by breaking α-1,4-glycosidic linkages. The application of α-amylases in various industries has made the large-scale productions of these enzymes crucial. Thermostable α-amylase that catalyses starch degradation at the temperatures higher than 50 °C is favourable in harsh industrial applications. Due to ease in genetic manipulation and bulk production, this enzyme is most preferably produced by microorganisms. Bacillus sp. and Escherichia coli are commonly used microbial expression hosts for α-amylases (30 to 205 kDa in molecular weight). These amylases can be purified using ultrafiltration, salt precipitation, dialysis, and column chromatography. Recently, affinity column chromatography has shown the most promising result where the recovery rate was 38 to 60% and purification up to 13.2-fold. Microbial thermostable α-amylases have the optimum temperature and pH ranging from 50 °C to 100 °C and 5.0 to 10.5, respectively. These enzymes have high specificity towards potato starch, wheat starch, amylose, and amylopectin. EDTA (1 mM) gave the highest inhibitory effect (79%), but Ca2+ (5 mM) was the most effective co-factor with 155%. This review provides insight regarding thermostable α-amylases obtained from microbial sources for industrial applications.