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Hemicellulose is an important component of the plant cell wall which vary in structure and composition between plant species. The research of hemicellulose structures is primarily focused on fast-growing plants during xylogenesis, with slow-growing and rare trees receiving the least attention. Here, hemicellulose structure of the rare species Castanopsis hystrix during xylogenesis was analyzed. Acetyl methyl glucuronide xylan was the most common type of hemicellulose in C. hystrix, with a unique tetrasaccharide structure at the reducing end. Hemicellulose type, structure, molecular weight, thermal stability, biosynthesis and acetyl substitution content and pattern remained stable during the xylogenesis in C. hystrix, which could be attributed to its slow growth. The stable polymer type, low side chain modification and high acetyl substitution of hemicellulose throughout the stems are among the reasons for the hardness and corrosion resistance properties of C. hystrix wood. Genetic modification can be used to improve these properties.

The acetylation of xylan has a great influence on the physiology of plants and the properties of lignified tissues. However, the effect of acetylation on the crystallization of xylans is still unclear. In this study, homogeneous acetylation of deacetylated β-(1–4)-d-xylans to different degree of substitution (DS) was carried out. Two precipitation methods, i.e. ethanol and water, were used to precipitate acetylated xylans. With the assistance of perpropionylation and HMBC NMR spectra, the DS of acetylation was accurately determined. The crystallization properties of acetylated xylans at different DS were evaluated by X-ray diffraction. For ethanol precipitated acetylated xylans, it is amorphous at all DS except at DS = 2 showing diffraction peaks of xylan diacetate crystal. For water precipitated acetylated xylans, it shows diffraction peaks of xylan hydrate crystal between DS 0 and DS 0.6, while the appearance of xylan diacetate crystal peaks starts at DS 1.96. The forming of xylan diacetate crystal is very abrupt with the changes of DS.

Cotton fiber is favored by people because of its good moisture absorption, heat preservation, soft feel, comfortable wearing and other excellent performance. In recent years, due to the destruction of the ozone layer, the intensity of ultraviolet radiation at ground level has increased. Cotton fiber will degrade under long time ultraviolet irradiation, which limits the outdoor application of cotton fiber. In this study, titanium dioxide (TiO

Four carboxylic acids with different acidities and chemical structures were applied to produce carboxylic cellulose nanocrystals (CNCs) with the assistance of ultrasonication. The effects of acid c...

Hemicelluloses account for 15–30 % of the lignocellulosic biomass and are considered as abundant renewable biopolymers. They are the major byproducts from pulping and other biorefinery industries, but are highly underutilized and usually burned as low value fuel. In this study, glucuronoxylan recovered from dissolving pulp mill were used to produce a high-quality bio-based emulsifier. Octylamine, dodecylamine and hexadecylamine were used to modify oxidized glucuronoxylan in order to improve the amphipathic properties of glucuronoxylan. Alkyl aminated glucuronoxylan emulsions showed smaller droplet size, higher emulsion activity and lower zeta potential compared to that of unmodified glucuronoxylan emulsions. With the increasing of alkyl contents, the emulsifying properties were improved. However, when the contents of alkyl groups increased beyond a certain value, the emulsifying properties were not changed significantly. Furthermore, the alkyl chain length also had a positive impact on emulsifying properties of alkylamine aminated glucuronoxylans. These results suggest that alkyl aminated glucuronoxylans have the potential to substitute for petroleum-based emulsifiers in many applications.

Environmentally friendly cellulose/GO/TiO2 hydrogel photocatalyst has been successfully fabricated via a green, simple, and one-step method and evaluated as the photocatalyst and adsorbent for the removal of methylene blue (MB). The XRD and FTIR analysis suggested the strong interaction among cellulose, GO and TiO2, resulting from the formation of hydrogen bonds. Due to the unique porous structure of cellulose hydrogel and introduction of GO, the cellulose/GO/TiO2 hydrogel showed superior (degradation ratio ∼ 93%) and reproducible (no significant change during the ten consecutive cycles) performance in the removal of MB under UV light. Consequently, the prepared cellulose/GO/TiO2 hydrogel can be applied as an eco-friendly, high-performance, reproducible, and stable photocatalyst and adsorbent for the removal of MB. This green hydrogel is a promising candidate for dye wastewater treatment. Moreover, this work is expected to extend the scope of bio-templated synthesis of other nanomaterials for various applications.

Xylan is a highly abundant plant-based biopolymer. Original xylans in plants are in an amorphous state, but deacetylated and low-branched xylan can form a crystalline structure with water molecules. The utilizations of xylan have been limited to bulk applications either with inconsistency and uncertainty or with extensive chemical derivatization due to the insufficient studies on its crystallization. The applications of xylan could be greatly broadened in advanced green materials if xylan crystals are effectively utilized. In this paper, we show a completely green production of nano-sized xylan crystals and propose their application in forming Pickering emulsions. The branches of xylan were regulated during the separation step to controllably induce the formation of xylan hydrate crystals. Xylan hydrate nanocrystals (XNCs) with a uniform size were successfully produced solely by a mild ultrasonic treatment. XNCs can be adsorbed onto oil–water interfaces at a high density to form highly stable Pickering emulsions. The emulsifying properties of XNCs were comparable to some synthetic emulsifiers and better than some other common biopolymer nanocrystals, demonstrating that XNCs have great potential in industrial emulsification.

Xylans play an important role in dispersing and lubricating cellulose fibrils in lignocellulosic plant cell walls. However, the effect of acetylation on the dispersing and emulsifying properties of xylan is still unclear. In this study, we show that the natural degree of acetylation is vital to ensure xylan an excellent water solubility and emulsifying ability. Alkali extracted xylans were artificially acetylated to degree of substitution (DS

Using originally isolated xylan-type hemicelluloses for material application suffers from poor mechanical properties including low tensile strength and brittleness. The subsequent chemical modifications of hemicelluloses are facing the problems of high costs and toxic chemicals. Consequently, this study tried to investigate the factors affecting the film-forming properties of the originally isolated xylan-hemicelluloses and promoting their material properties from the extraction step. Two different extraction methods, a one-step alkali or alkaline peroxide solution method and a two-step alkali extraction-delignification method were used to extract the hemicellulose with different chemical structures from sugarcane bagasse. For the two-step alkali extraction-delignification method, hemicelluloses were first extracted by alkali solution and then delignified by dioxane/water, hydrogen peroxide solution or sodium hypochlorite solution. The lignin contents of all the extracted hemicelluloses ranged from 1.6%–9.5%, of which the lowest value was obtained through delignification by sodium hypochlorite. The number average molecular weight ranged from 8200 to 26800, while the xylan/arabinan ratio ranged from 5.0 to 9.1. The hemicelluloses were characterized and processed into films. Tensile strength of films could be considerably improved up to ˜52% when using sodium hypochlorite solution as the delignification agents and the lignin content was greatly reduced for the hemicellulose fraction. Statistical models were generated between film mechanical properties and hemicellulose structural characteristics. The models predicted that hemicellulose with higher molecular weight, more linear structure and lower lignin content would result in better mechanical properties.

Both value-added utilization of low-rank renewable feedstocks to prepare catalytic materials and selective transformation of bioderived aldehydes are very attractive topics. Herein, lignosulfonate, a waste by-product from the paper industry, was simply assembled with ZrCl4 under non-toxic hydrothermal conditions for scalable preparation of Zr-containing polyphenolic biopolymer catalysts (Zr LS). Systematic characterizations indicated that the strong coordination between Zr4+ and phenolic hydroxyl groups in lignosulfonate led to the formation of strong Lewis acid-base couple sites (Zr4+−O2−) and porous inorganic-organic framework structure (mesopores centered at 6.1 nm), while the inherent sulfonic groups in lignosulphonate could serve as Bronsted acidic sites. The cooperative role of these versatile acid−base sites in Zr LS afforded excellent catalytic performance for Meerwein-Ponndorf-Verley (MPV) reaction of a broad range of bioderived platform chemicals under mild conditions (80 °C), especially of furfural (FF) to furfuryl alcohol (FA), in quantitative yields (96%) with high FA formation rate of 9600 μmol g−1 h−1 and TOF of 4.37 h−1. Kinetic studies revealed that the activation energy of the MPV reduction of FF was as low as 52.25 kJ/mol, accounting for the high reaction rate. Isotopic labelling experiments demonstrated direct hydrogen transfer from the α-C of 2-PrOH to the α-C of FF on acid-base sites was the rate-determining step. Moreover, Zr LS showed good recyclability for at least seven reaction cycles.

Glucuronoxylans, a low-value byproduct from pulping, biomass pretreatment and other biomass processing industries, have been considered to be potentially used as emulsifiers. However, the poor amphipathic property of glucuronoxylans limits their application as emulsifiers. To improve the amphipathic property of glucuronoxylans and develop high quality natural-based/green emulsifiers, glucuronoxylans were chemically modified by alkenyl succinic anhydrides to produce a novel emulsifer. The effects of degree of substitution (DS) and alkenyl chain length on the emulsifying properties of long-chain succinic anhydride modified glucuronoxylans were investigated. Dodecenyl succinic anhydride–glucuronoxylans (DDSA–glucuronoxylans) emulsions showed much smaller droplet size, lower zeta potential, higher emulsifying activity and better emulsion stability compared to that of glucuronoxylans emulsion. When DS increased from 0.014 to 0.09, the emulsifying properties of DDSA–glucuronoxylans were improved. However, when DS increased beyond 0.09, the emulsifying properties were not changed significantly. Furthermore, the alkenyl chain length also has a positive impact on emulsifying properties of long-chain succinic anhydride modified glucuronoxylans. These results suggested that long-chain succinic anhydride modified glucuronoxylans had a potential to be used as emulsifiers, while the DS and chain length should be kept at a proper value.

Noble metal nanoparticles (MNPs) and proper structural supporting materials can be fabricated into a sheet like catalytic composite, which is called dip-catalyst. Dip-catalyst is accentuated by its highly convenient deployment, easy separation and great recyclability. Polymeric film- or paper-based dip-catalyis has problems of low catalytic efficiency and MNP leaching or aggregation. Bacterial cellulose (BC) with its naturally nano-porous surface structure can efficiently support and stabilize the MNPs. Further compositing with plant fibers, the economy, catalytic efficiency and mechanical stiffness of the dip-catalyst may be greatly improved. However, the aqueous phase recyclability of the cellulosic fiber-based dip-catalyst is still limited, impairing its broad application. In this study, polyethylenimine (PEI) was used to crosslink BC-fiber and fiber–fiber within the BC-fiber matrix to improve the wet strength of the dip-catalyst. In detail, plant fibers were composited with the Au NP-embedded BC to fabricate a dip-catalyst through the paper handsheet making method. During the process, PEI was added as a wet-strength agent. The catalytic activity of this dip-catalyst was evaluated on the reduction of 4-nitrophenol in water by using NaBH4. Adding 1% PEI reduced the turnover frequency of 10% Au-BC sheet from 131.9 to 53.7 h−1, but greatly improved its recyclability and reusability. After reused for 30 times, reaction rate and yield was well maintained without impaired for the Au-BC catalytic sheets with PEI additions. This study promotes much broader applications for the BC-fiber dip-catalyst in chemical reactions.

Acid hydrolysis using concentrated mineral acids is currently the most applied method to prepare nanocellulose, specifically cellulose nanocrystals (CNCs). However, the method exhibits several critical defects, namely it is hazardous to the environment and human body, causes corrosion to the process equipment and the overdegradation of raw cellulose material, is high cost, and so on. Moreover, chemical modification to the functional groups of the CNC products is usually needed for further applications, also leading to extra costs. In this work, an innocuous weak acid (citric acid) was applied to prepare cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) from bleached bagasse pulp accompanied by simultaneous modifications of the functional groups on their molecular interface. It was discovered that with the small aid of ultrasonication at the appropriate preparation stage, citric acid could overcome the difficulties of hydrolyzing cellulose caused by its weak acidity, and CNCs were successfully produced with good nanoscales and high yield. CNCs with a diameter of 20–30 nm and length of 250–450 nm and CNFs with a diameter of 30–60 nm and length of 500–1000 nm were achieved. Up to 32.2% of the original bagasse pulp was converted to CNCs via citric acid hydrolysis with the assistance of ultrasonication, compared to only about 10.6% of the CNC yield without ultrasonication under the same hydrolysis conditions. At least one carboxylic group of the citric acid was simultaneously introduced to the cellulose via esterification during acid hydrolysis to form carboxylic CNCs and CNFs, which is important for further functionalization. Contents of carboxylic acid groups up to 0.65 mmol g−1 for CNCs and 0.30 mmol g−1 for CNFs were obtained, which endowed the CNCs and CNFs with highly stable dispersibility. Over 90% of the citric acid could be easily recovered through a rotary evaporator. The carboxylic CNCs and CNFs presented in this work offer commercial success and lower toxic risks, which means they have the potential to find applications as environmentally friendly, sustainable, and new bio-based nanomaterials in high-tech fields, such as biomaterials.

Hemicellulose, one of the most abundant biopolymers next to cellulose, has been considered as a potential substitute to synthetic polymers. Film casting from water is the most basic route for material applications of xylan. However, depending on plant sources and separation methods, xylans do not always form films and the related mechanism is unclear, which significantly hinders their material applications. We extensively characterized various fractions of bagasse xylan to understand the molecular features promoting the film formation. The side groups of xylans or impurities contributed to the prevention of excessive aggregation or crystallization of xylan molecules, leading to the film-forming capacity. However, once the film is formed, the side groups do not seem to be necessarily contributing to the mechanical resistance.

Environmentally friendly cellulose/GO/TiO

Paper-based electrodes are of special interest for the industry due to their degradability, low cost, ion accessibility, and flexibility. However, the poor dispersibility and stability of loading conductive fillers, for example, carbon nanotubes (CNTs), limit their applications. In this study, bacterial cellulose (BC) was embedded within the cellulosic fiber matrix to prepare a paper substrate with a dual fiber matrix structure. BC with its unique nanoporous surface structure assisted the adsorbing, dispersing, and stabilizing of CNTs; cellulosic fibers reduced the cost, enhanced the ion accessibility, and improved the rigidity of the material. The prepared paper electrodes exhibited a high conductivity up to 5.9 × 10

Super adsorbents exhibit great potential to remove pollutants from media or store considerable amounts of water, which may undermine the pressure triggered by environmental pollution and shortage of water resources. Super adsorbents made from biopolymers have been an attractive topic because of biodegradability, renewability and outstanding adsorption capacity. Hemicelluloses are a type of biopolymers very abundant in agricultural, forestry and pulping industrial wastes. Hemicellulose-based bio-adsorbents are thriving because the inherent chemical structures and physical properties of hemicelluloses make themselves easy to be processed into matrix materials applicable in super adsorbents. This review summarizes recent studies in hemicellulose-based bio-adsorbents, i.e. hydrogels and active carbons, from the perspectives of types, applications, fabrication methods, the elements affecting the adsorption performance and the kinetics of adsorption process, which thus helps to further improve the properties of hemicellulose-based bio-adsorbents and to promote the industrial production and utilization of hemicelluloses and hemicellulose-based bio-adsorbents.

Arabinoxylan (AX) was extracted from sugarcane bagasse and modified through crosslinking with glutaraldehyde (GA). The effects of crosslinking degree on the rheological and coating properties of glutaraldehyde crosslinked arabinoxylan (GAX) were investigated. To better evaluate the degree of crosslinking, the crosslink index was used to represent the degree of crosslinking for the GAX in this study. The viscosity of the GAX solution increased when the degree of crosslinking increased, and the solution demonstrated non-Newtonian flow behavior. A high degree of crosslinking was detrimental to the film and coating properties of the GAX. At an optimum degree of crosslinking, the tensile strength of the GAX films increased by approximately 170% and 60% compared with that of the AX and GAX with the highest degree of crosslinking, respectively; the tensile strength of the GAX-coated paper increased by approximately 15% compared with that of the GAX with the highest degree of crosslinking. When calcium carbonate was mixed with the paper coating adhesives, the GAX showed comparable coating properties to that of polyvinyl alcohol, demonstrating its potential to substitute petroleum-based paper coating adhesives.

Enzymatic pretreatment has shown great potential in making the disintegration of cellulosic fibers to fibrils cost-effectively and environmental-friendly. In this study, an extensive commercial endoglucanase was used to pretreat cellulosic fibers for fibrillation. The pretreatment time and the enzyme dosage were optimized using response surface methodology. A 100% fiber recovery was obtained at endoglucanase usage of 9.0 mg/g (substrate) and pretreatment time of less than 3.0 h. A highly fibrillated and fractured surface of pretreated fibers was observed after 0.5 h of pretreatment compared to native fibers. Meanwhile, the progressive deconstruction of cellulosic fibers was occurred with the enzymatic pretreatment time increasing. The degree of deconstruction of fibers was evidenced by changes of the fiber microstructure, such as the inter-/intra-molecular H-bonds, the β-1,4-glucosidic linkages, crystallinity and crystallite size. These discoveries provide new insights into a more efficient and economic pretreatment methods for the disintegration of fibrils from cellulosic fibers.

Bacterial cellulose (BC) with its ultrafine nano-reticular structure may provide great support and distribution to metal nanoparticles. In this study, polyethylenimine was introduced into dialdehyde BC to improve the binding stability between BC and palladium (Pd) nanoparticles. The Pd nanoparticle-embedded BC (Pd-BC) was further composited with plant fibers to fabricate a paper-like “dip-catalyst” through a paper handsheet making method. This catalyst has structural features including the fact that PEI-BC provides a great distribution and binding stability to Pd particles, while plant fibers as a supporting component may reduce the cost of fabrication, provide mechanical strength, and improve the contact between the reactants and Pd particles due to their porosity. The dip-catalyst or catalyst sheet was employed in the Suzuki–Miyaura reaction, providing a high reaction rate, a yield of nearly 100% and a high turnover frequency (TOF). It demonstrated an easy reusability and an extensive recycling capability with the same catalyst sheet being used 26 times and still having a yield of nearly 90%. This catalyst sheet produced from sustainable materials is expected to play an important role in organic synthesis.

Deacetylated xylan molecules with a low degree of branching can form crystals with water molecules, namely xylan hydrate crystals (XHC), leading to a low water solubility but other unique properties of xylan. However, cutting-edge applications of XHC have never been explored. Surface modified carboxymethylated xylan hydrate crystals (CmXhc) with great amphiphilic and rheological properties were produced through appropriate control of degree of substitution. Nanoscale CmXhc was successfully produced through ultrasonic treatments. Nanoscale CmXhc showed an ability to disperse multi-walled carbon nanotubes (MWCNT) in water with a recorded high CNT concentration of 40 mg/mL and a high dispersion efficiency of 91.7%. The CmXhc can also act as an anchoring agent to bind CNT to paper surfaces making the high concentration dispersion as a conductive paper coating or printing ink. The CmXhc-dispersed MWCNT coated paper demonstrated a high conductivity, specific capacity and capacitance stability, although subject to tuning for improvements, serving as a potential paper-based electrode for supercapacitors.

Cassava is one of the three major potato crops due to the high starch content in its tubers. Unlike most current studies on the utilization of cassava tubers, our research is mainly focused on the stem of cassava plant. Through nuclear magnetic resonance (NMR), fourier transform infrared spectrometer (FTIR) and other methods, we found that cassava stalk hemicellulose consists of β-1,4 glycosidic bond-linked xylan backbone with a tetrasaccharide reducing end and decorated with methylated glucuronic acid, acetyl groups and a high degree of arabinose substitutions. Hemicellulose content gradually increased from the upper to the lower parts of the stem. The apical part of cassava stalk contained more branched and heterogeneous glycans than the middle and basal parts, and the molecular weight of hemicellulose increased from top to bottom. Our findings will be helpful in understanding of structural variations of cassava hemicellulose during xylogenesis, as well as in better utilization of cassava plant waste in industry.

To protect forest resources and increase the value of agro-industrial residues, it would be helpful to produce paper-based materials from non-woody or recycled fiber resources. This study investigated the reinforcement mechanism of bacterial cellulose (BC) on paper sheets made from different sources including softwood, hardwood, sugarcane bagasse, bamboo, wheat straw, and recycled fiber, which represent a selection of high quality, medium quality, and low quality fibers. The results showed that by maintaining BC addition at a low level of 0.5–1.5% (total paper dry weight), the paper sheets made from high and medium quality fibers have the maximum tensile index improvement, with 5–25%. The tensile index of low quality fiber including wheat straw pulp and recycled fiber pulp increased slightly and gradually with the level of BC addition; at 5% BC addition, the tensile indexes increased by 9 and 40%, respectively. To investigate the BC reinforcement mechanism, different fiber characteristics, SEM images of BC reinforced paper, BC retention rate on paper, and the effects of dispersant addition were evaluated. It was found that high BC addition or retention rate in paper sheets do not necessarily result in good BC reinforcement effects but that proper dispersion of BC is important.

Bacterial cellulose (BC) was used to reinforce paper sheets made from non-woody fibers, e.g. sugarcane bagasse. BC produced from static and agitated fermentation methods was mixed with bleached sugarcane bagasse pulp (BSBP) to produce composite paper sheets. BC from static culture had a higher degree of polymerization, crystallinity, and crystallite width. Adding BC at a low ratio (

Hybrid poplars (Populus nigra L. × Populus maximowiczii A.) were genetically modified through antisense insertion of the 4-coumarate:coenzyme A ligase (4CL) gene. Compositional changes in response to this genetic change were measured in the field after 2 and 3 years of growth. The stem samples were treated with either green liquor or dilute acid pretreatments, representing alkaline and acid pretreatments. The enzymatic saccharification of the untreated and pretreated transgenic poplars were evaluated. After transgenic species were transplanted into the environment, they showed reduced recalcitrance to chemicals (i.e., pretreatments) and enzymes despite their lignin content and S/V ratio being comparable to those of the wild types. Compared to the field-grown poplars, the sugar yield increased up to 103% for untreated transgenic samples and increased 22% for acid- and green liquor-pretreated transgenic samples. This shows that field-grown transgenic hybrid poplars with modified lignin biosynthesis have imp...

This study investigated the impact of cellulose polymorphs on cellulose nanocrystals (CNCs) preparation. Cellulose samples with different types of polymorphs (cellulose I, cellulose II, and cellulose III) were prepared. Subsequently, CNCs were obtained from the above cellulose samples by sulfuric acid hydrolysis. The initial cellulose and CNCs were characterized by X-ray diffraction (XRD), thermo gravimetric analysis (TGA), scanning electronic microscopy (SEM) and particle size distribution (PSD). A comparative study showed that the properties of CNCs were closely related to the polymorphs of initial cellulose. The original polymorphs of cellulose I and cellulose II were retained, while that of cellulose III was converted back to cellulose I during the sulfuric acid hydrolysis process of CNCs preparation. For cellulose I and cellulose II, the crystallinity of both corresponding CNCs continuously increased with the increase of sulfuric acid concentration, until reaching a maximum at approximately 84.0%, while the crystallinity of CNCs obtained from cellulose III was slightly affected by sulfuric acid concentration. The yields of CNCs obtained from cellulose II and cellulose III with 61 wt% H2SO4 were extremely high, reaching 46.8% and 43.4%, respectively. Smaller CNCs particles with short-length were obtained by sulfuric acid hydrolysis of cellulose II. In addition, the properties (yield, dimension and thermal degradation behavior) of CNCs obtained from cellulose III were more susceptible to the acid concentration compared with those of CNCs obtained from cellulose I.

This study investigated the possibilities of making valuable products from corn ethanol byproducts and providing the beverage industries more variety of high quality emulsifiers other than gum arabic. An arabinoxylan-protein gum (APG) was extracted from distillers' grains (DG), a low-value corn ethanol byproduct, and modified through acylation with succinic anhydride. The effects of pH and degree of substitution (DS) on the emulsifying properties of succinylated APG, referred to as SAPG, were investigated. Emulsion particle size and stability of APG and gum arabic were comparable at pH 3.5–6.5. Succinylation could enhance the emulsifying properties of APG. Compared to gum arabic, at pH 5, SAPG had much smaller particle size and better stability than gum arabic. The results suggested that SAPG, compared to gum arabic, could be a comparable emulsifier at low pH values and a better emulsifier at neutral pH values.

Cladophora, a fresh-water green macroalgae, has unique cellulose properties and thus may be promising for production of cellulose nanofibrils (CNFs). Cellulose was extracted from Cladophora glomerata and subjected to microfluidization with or without enzymatic hydrolysis pretreatment to produce CNFs. Increasing microfluidization passes produced smaller algal CNFs with more uniform sizes and lower crystallinity. Combining microfluidization with an enzymatic hydrolysis pretreatment, the algal CNFs’ crystallinity decreased further, but the diameter distribution showed little change. The algal CNFs were compared to CNFs produced from bleached eucalyptus pulp (BEP), with the algal CNFs having significantly higher crystallinity, smaller diameter and better thermal stability. The XRD spectra of algal and BEP CNFs were simulated by Mercury 3.0 software. The results indicated that BEP CNFs are mainly cellulose Iβ with a random orientation, while algal CNFs are likely a hybrid of cellulose Iα with preferred orientations along the [100] and [010] axes with a March–Dollase factor of 0.65.

Coatings contribute to about 10% of the overall cost of paper production of which, the binder is the highest cost component in the formulation. In addition to costs, the binders that are currently being used are synthesized from fossil fuel feedstock raising concerns towards the sustainability of paper coatings. Furthermore, papers coated with waxes, polyolefins and other synthetic materials are difficult to recycle or compost. These challenges inherent with synthetic binders can be addressed by using renewable, plant based binders. This research focused on an abundant and underutilized source of hemicellulose based binders (DG gum) that can be extracted from distiller's dried grains. The extracted binder was compared with polyvinyl alcohol (PVA) in a coating formulation consisting of 10:1 CaCO3 to binder formulation coated on light weight paper. Cobb test, dry and wet tensile tests, optical properties (brightness, color, opacity), water vapor transmission rate (WVTR) analysis were performed to compare the hemicellulose based binder with PVA. The results indicate water absorptivity reduction by 25% for both DG gum and PVA coatings from the base paper value. Dry tensile index was lower with higher coating weights for both coatings with similar performance. The performance on WVTR analysis for both coatings was also comparable. No significant differences in optical properties after coating were observed from that of the base paper. These results suggest that hemicellulose based binder extracted from distiller's grains has the potential to replace synthetic binders in paper coating formulations.

Cellulose synthase A genes (CesAs) are responsible for cellulose biosynthesis in plant cell walls. In this study, functions of secondary wall cellulose synthases PtrCesA4, PtrCesA7-A/B and PtrCesA8-A/B were characterized during wood formation in Populus trichocarpa (Torr. & Gray). CesA RNAi knockdown transgenic plants exhibited stunted growth, narrow leaves, early necrosis, reduced stature, collapsed vessels, thinner fiber cell walls and extended fiber lumen diameters. In the RNAi knockdown transgenics, stems exhibited reduced mechanical strength, with reduced modulus of rupture (MOR) and modulus of elasticity (MOE). The reduced mechanical strength may be due to thinner fiber cell walls. Vessels in the xylem of the transgenics were collapsed, indicating that water transport in xylem may be affected and thus causing early necrosis in leaves. A dramatic decrease in cellulose content was observed in the RNAi knockdown transgenics. Compared with wildtype, the cellulose content was significantly decreased in the PtrCesA4, PtrCesA7 and PtrCesA8 RNAi knockdown transgenics. As a result, lignin and xylem contents were proportionally increased. The wood composition changes were confirmed by solid-state NMR, two-dimensional solution-state NMR and sum-frequency-generation vibration (SFG) analyses. Both solid-state nuclear magnetic resonance (NMR) and SFG analyses demonstrated that knockdown of PtrCesAs did not affect cellulose crystallinity index. Our results provided the evidence for the involvement of PtrCesA4, PtrCesA7-A/B and PtrCesA8-A/B in secondary cell wall formation in wood and demonstrated the pleiotropic effects of their perturbations on wood formation.

The impact of field-grown transgenic trees on wood characteristics and enzymatic saccharification was evaluated. Genes 4CL and CAld5H were down regulated or overexpressed to modify the lignin content or structure (S/V ratio) on black cottonwood (Populus trichocarpa Nisqually-1). These transgenic trees were grown in the real environment and evaluated after 2 and 3 years. The results exhibited that the lignin content for most of the transgenic black cottonwoods increased compared to their initial lignin content when grown inside the greenhouse. The lignin contents approached those of the wild types. Acid and green-liquor pretreatments were applied to the transgenic wood saw dust samples. Cellulase mediated saccharifications were then conducted for the pretreated and untreated samples. Sugar yield and carbohydrate saccharification efficiency of the enzymatic saccharification for most of the transgenic trees were observed to be higher than those of the wild types even though their lignin contents became similar.

Bacterial cellulose (BC) is a green biopolymer suitable for heavy metal ion removal from aqueous solution due to its nano-porous microstructure. Polyethyleneimine-bacterial cellulose (PEI-BC) was prepared by reductive amination of dialdehyde BC with polyethyleneimine. The capacity of PEI-BC in Cu(II) and Pb(II) adsorption from aqueous solution was investigated. The adsorption kinetics could be well expressed by pseudo-second-order model and the adsorption isotherm data were well fitted with Freundlich model. Adsorption processes of Cu(II) and Pb(II) by PEI-BC reached equilibrium very rapid in 30 and 60min, respectively. The maximum adsorption capacity of PEI-BC on Cu(II) and Pb(II) was found to be 148 and 141mg/g, respectively, which was higher than that of unmodified BC and other modified BC reported. PEI-BC also showed good reusability in the adsorption of Cu(II) and Pb(II). This study demonstrates that polyethyleneimine modification makes BC a potential bioadsorbent for heavy metal ion removal in waste water.