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Pulp and paper mills represent a major platform for the use of abundant, renewable forest-based biomass as raw material. The pulping processes produce a large amount of black liquor solids, which is currently burnt in a conventional Tomlinson recovery boiler for recovery of energy and inorganic chemicals. This combustion technology can recover chemicals with good efficiency, and steam and power can be produced for the mills. However, Black Liquor Gasification (BLG) can be used to substitute for the combustion process for potential higher energy efficiency, lower greenhouse gas emissions, and more safety. With BLG technology, current pulp and paper mills can be extended into future biorefineries. In this work, a thermodynamic equilibrium model using Gibbs free energy minimization approach and the software FactSage are utilized to analyze the thermodynamic equilibrium constraints of the complex multiple phase reactions and the effects of different operating conditions during black liquor gasification. The modeling results can help better understand the black liquor gasification process and be useful in process modeling and analysis of the future BLG-based biorefinery. [ABSTRACT FROM AUTHOR]

Abstract: Pulp and paper mills represent a major platform to use more effectively an abundant, renewable bio-resource – wood. Modification of the modern day pulp mills into integrated forest biorefineries (IFBR) presents an excellent opportunity to produce, in addition to valuable cellulose fiber, co-products including fuel grade ethanol and additional energy, thus resulting in increased revenue streams and profitability and potentially lower the greenhouse gas emissions. A process model to simulate the integrate forest biorefinery manufacturing pulp and other co-products has been developed. This model has been used to compare three integrated biorefinery scenarios: the conventional Kraft pulping process, the pulp mill-based IFBR with hemicelluloses extraction prior to pulping for ethanol production, and the pulp mill-based IFBR with both pre-extracted hemicelluloses and the short fiber for ethanol production. Based on a fixed feedstock throughput of 2000dryMgwood/day, results show that the pulp mill-based IFBR with both pre-extracted hemicelluloses and the short fiber cellulose converted to ethanol can produce 0.038MMm3 (10.04MMgal) ethanol per year at a minimum ethanol selling price (MESP) of $491/m3 ($1.86/gal). The economic feasibility of IFBR can be further improved by using further improvements in the pre-extraction process, other biomass such as corn stover for producing ethanol, and taking advantage of the economies of scale. [Copyright &y& Elsevier]

Abstract: The effects of five different biomass species and their chemical composition on the overall process efficiency and economic performance considering feedstock availability and feedstock costs to manufacture ethanol from lignocellulose were studied. First is a comparison of ethanol production and excess electricity generated between different biomass species. Results show that, at the same feedstock rate of 2000Mgday−1, aspen wood has larger ethanol production than switchgrass, hybrid poplar and corn stover, while the excess electricity generated is as follows in increasing order: aspen

Abstract: Biorefineries process bioresources such as agriculture or forest biomass to produce energy and a wide variety of precursor chemicals and bio-based materials, similar to the modern petroleum refineries. Industrial platform chemicals such as acetic acid, liquid fuels such as bioethanol and biodegradable plastics such as polyhydroxyalkanoates can be produced from wood and other lignocellulosic biomass. Biorefineries use a variety of separation methods often to produce high value co-products from the various feed streams. In this paper, a critical review of separation methods and technologies related to biorefining including pre-extraction of hemicellulose and other value-added chemicals, detoxification of fermentation hydrolyzates, and ethanol product separation and dehydration is presented. For future biorefineries, extractive distillation with ionic liquids and hyperbranched polymers, adsorption with molecular sieve and bio-based adsorbents, nanofiltration, extractive-fermentation, membrane pervaporation in bioreactors, and vacuum membrane distillation (VMD) hold significant potential and great promise for further investigation, development and application. [Copyright &y& Elsevier]

Paper manufacturing consists of the sequential removal of over 90% of the water from pulp through gravity, vacuum dewatering, pressing and thermal drying. Control of moisture content is important for paper quality and energy economy. Current strategy for the control of moisture content uses a feedback sensor at the end of the process to adjust the dryers. This introduces a long dead-time and causes excessive use of the dryers, which translate to limitations in performance, robustness and inefficient energy usage. In this paper, we investigate a new control approach in which in-process moisture contents are estimated using air-flow as surrogate measurements, and the pressure settings in the vacuum dewatering boxes are adjusted according to the surrogate measurements. A pre-emptive control algorithm is developed which has the ability to decouple and eliminate the effects of the disturbances that occur upstream in the process from the downstream. Robustness analysis and simulation studies suggest that as long as the surrogate measurements are accurate, the proposed control scheme will be robust and accurate. [ABSTRACT FROM AUTHOR]

A mathematical model describing the convective heat and mass transfer during through air drying of paper under commercial air temperature and flow conditions is reported. The model takes into account the heat and mass transfer through the sheet, and the polymeric carrier fabric. Experimental set-up capable of studying through air drying under commercial conditions is also reported. It is shown that the polymeric carrier fabric is dried significantly earlier than the sheet. Even though there is no constant-rate drying period during through air drying, the sheet and fabric temperature does remain constant during majority of the drying. This constant temperature under commercial conditions is lower than the adiabatic saturation temperature corresponding to the inlet air. Sensitivity analysis of through air drying operating parameters indicates that inlet air temperature has the highest effect on the drying rate, followed by the applied differential pressure. Inlet air humidity has the least effect on the drying rate. A mathematical model describing the convective heat and mass transfer during through air drying of paper under commercial air temperature and flow conditions is reported. The model takes into account the heat and mass transfer through the sheet, and the polymeric carrier fabric. Experimental set-up capable of studying through air drying under commercial conditions is also reported. It is shown that the polymeric carrier fabric is dried significantly earlier than the sheet. Even though there is no constant-rate drying period during through air drying, the sheet and fabric temperature does remain constant during majority of the drying. This constant temperature under commercial conditions is lower than the adiabatic saturation temperature corresponding to the inlet air. Sensitivity analysis of through air drying operating parameters indicates that inlet air temperature has the highest effect on the drying rate, followed by the applied differential... [ABSTRACT FROM AUTHOR]

Conventional multi-cylinder drying of paper and board involves a mixture of conductive drying from steam-heated dryer cylinders and convective drying by the flow of heated air over the surface of the paper web in the pockets. Pocket ventilation is a critical component in assisting heat and mass transfer during the drying process but is the primary contributor toward removing evaporated water from the web. Air temperature, velocity, and humidity are critical parameters involved in the convective drying process. This paper covers an experimental study involving the design and development of a small lab-scale setup for convective drying of various grades of paper and board, monitoring multiple parameters like paper temperature, moisture content, air humidity, temperature, and velocity measured in situ as the drying proceeds with continuous and accurate sampling capabilities for all parameters in the sample and the system. Instantaneous drying rates, heat, and mass transfer coefficients were also deduced for every time step till the paper completely dried. Furthermore, the coefficients obtained were also reported in the form of dimensionless correlations, and the results were compared against traditional correlations used in the modeling of paper drying. This data will be useful in process development, modeling, design, and the paper drying process simulation. [ABSTRACT FROM AUTHOR]

Ionic liquids (ILs) including novel superbase-derived ILs and imidazolium-based ILs with the potential to be used as green solvents for biomass utilization should be deeply evaluated with respect to their corrosion ability towards metallic equipment in industrialization. Herein, the corrosion susceptibility of 304SS in [DBUH][CH3CH2OCH2COO] was investigated for the first time and compared with that in common [EMIM][Ac] and [AMIM][Cl] by electrochemical, surface, and theoretical analyses. [DBUH][CH3CH2OCH2COO] exhibited an unprecedentedly excellent corrosion inhibition for 304SS compared to imidazolium-based ILs. This may be due to the presence of electron-donating carboxylate anions and macrocyclic superbase cations, which reacted with metals to form a compact layer and protected metals from damage. [EMIM][Ac] showed a slightly unfavorable corrosion inhibition compared to [DBUH][CH3CH2OCH2COO]. However, the corrosion rate of 304SS was dramatically increased in [AMIM][Cl] by increasing the temperature and water contents, which was reflected by pitting corrosion with plenty of pits (5–10 μm in diameter) on the 304SS surface after a polarization test. By studying the corrosion behaviour of five common steels in [DBUH][CH3CH2OCH2COO] and taking economy into consideration, 304SS with high Rct (26.69 × 105 Ω cm2) and Rp values (1230.8 Ω cm2) was the top priority for industrial equipment materials. According to the possible corrosion mechanism of metals in ILs from the viewpoint of DFT calculations and complex physico-chemical interactions, carboxylate ILs displaying outstandingly low contributions to corrosion particularly involving superbase cations or imidazolium cations and carboxylate anions with electron-donating groups such as –OCH2CH3, –OCH3, and –HC＝CH2 should be designed to mitigate corrosion damage in industrialized operations. [ABSTRACT FROM AUTHOR]

An experimental setup was developed to study the through air–drying characteristics of permeable grades such as tissue and towel under commercially relevant conditions of basis weight, airflow rate, temperature, and humidity conditions. The experimental setup is capable of evaluating the transient fluid flow, heat, and mass transfer characteristics of relatively larger samples (TAPPI standard hand sheets; 0.1524 m) and is capable of studying the effect of local heterogeneity and structure on convective heat and mass transfer. The system is capable of airflow rates of 0.5–10 m/s with corresponding high-speed data collection and acquisition for measuring important variables such as exhaust air humidity. To study the effect of nonuniformity, local temperature and velocity profiles can also be measured using grid of thermocouples and hot wire anemometers. The instantaneous drying rate and airflow characteristics during through air drying was measured and dry permeability, wet permeability, and convective heat and mass transfer characteristics were then calculated. The experimental results were verified by comparing with the results from literature. Typical experimental results were presented to show the effect of sheet basis weight, initial moisture content, and airflow rates on the drying characteristics for two different types of paper samples. [ABSTRACT FROM AUTHOR]

Natural macromolecules have attracted increasing attention due to their biocompatibility, low toxicity, and biodegradability. Pectin is one of the few polysaccharides with biomedical activity, consequently a candidate in biomedical and drug delivery Applications. Rhamnogalacturonan-II, a smaller component in pectin, plays a major role in biomedical activities. The ubiquitous presence of hydroxyl and carboxyl groups in pectin contribute to their hydrophilicity and, hence, to the favorable biocompatibility, low toxicity, and biodegradability. However, pure pectin-based materials present undesirable swelling and corrosion properties. The hydrophilic groups, via coordination, electrophilic addition, esterification, transesterification reactions, can contribute to pectin's physicochemical properties. Here the properties, extraction, and modification of pectin, which are fundamental to biomedical and drug delivery applications, are reviewed. Moreover, the synthesis, properties, and performance of pectin-based hybrid materials, composite materials, and emulsions are elaborated. The comprehensive review presented here can provide valuable information on pectin and its biomedical and drug delivery applications. [ABSTRACT FROM AUTHOR]

The performance of many products such as those made of containerboard or other paperboards is sensitive to moisture. Transient moisture profiles result in heterogeneities in mechanical properties and can often lead to catastrophic failure. Viewed as a composite porous medium the system comprises hygroscopic fibers and void spaces both of which are continuous. Furthermore, both phases conduct moisture by diffusion and for typical paperboards diffusion through the fiber matrix predominates at high moisture contents whereas vapor phase diffusion through the void space is dominant at lower values. Depending upon the external and initial conditions, competition between these two pathways and local sorption interplay and produce interesting effects, which can have significant impact on the mechanical performance of the composite medium. In order to delineate the different effects that can occur, we used a mathematical model for unsteady state diffusion to analyze the case of transient moisture transport through a paperboard exposed to differential humidity conditions on either side. Diffusion is assumed to occur along the thickness direction in the void space and in the fiber space. Local uptake of moisture is represented by the linear driving force approximation. A numerical solution of the mathematical model is sought. The dominant path for moisture transport can undergo a change from the fibers to the void spaces under large humidity differentials. A fiber conduction layer whose thickness develops with time and reaches a constant value at steady state is found. This raises the possibility of moisture response, which could depend on the direction of diffusion for significantly heterogeneous media. Another interesting feature is the development of minima in the moisture flux versus time curves, which are sensitive to the diffusion and local sorption parameters. Tracking such minima can provide a good method to tune the model parameters based on experimental flux data. The role of the interfacial region between the layers can affect the overall resistance and alter moisture content profiles significantly. Since similar ‘two-equation’ models have been proposed for other transport processes such as heat and momentum transfer, these results can have wider applicability. In particular, steady and unsteady profiles and fluxes can be exploited to yield information about the local and global transport coefficients for the heterogeneous medium under consideration. [Copyright &y& Elsevier]

[Display omitted] • Canna-inspired film is prepared by roll-to-roll and evaporation-induced self-assembly. • The first time bestowed with icephobicity to food freshness colorimetric sensing film. • The color changes are perceivable by inexpert and untrained users. • The film can apply for real-time visual monitoring of food freshness. Unsafe food cause serious threat to public health and the economy, exploiting effective food quality assessment strategies has attracted concerns worldwide. Herein, inspired by Canna micro-nano hierarchical structure, a generic, facile, and highly processable roll-to-roll and solvent evaporation-induced self-assembly fabrication method is introduced to fabricate regenerated cellulose based superhydrophobic and icephobic hierarchical colorimetric sensing film for real-time visual monitoring of food freshness. The synergistic effect from macromolecular chains attraction and nanoscaled aggregation renders the colorimetric sensing film with excellent mechanical strength of 105.07 MPa and superhigh shear modulus of 17.28 GPa. Upon applied tension, the vigorous intermolecular interactions make the film extraordinary structure stability. The optimized colorimetric sensing film exhibits microscaled pores for sensing performance and three-dimensional nanoflower morphologies for superhydrophobic (water contact angle of 155.1 °and roll-off angle of 7.8°) and icephobic that delay the freezing time of 40 μL water droplets (45 s to 265 s) and reduce the bonding strength of ice (599.72 kPa to 45.53 kPa). What counts is the first time bestowed with icephobicity to food freshness colorimetric sensing film, which mitigating the interference of the covered ice layer against the colorimetric, and providing a more reasonable monitoring in food freshness. These results benefit for stimulating new design principles of colorimetric sensing films, and also provide promising applications in extremely cold environments. [ABSTRACT FROM AUTHOR]

Highlights • A cost-efficient strategy to enhance enzymatic hydrolysis of poplar was proposed. • Mild NaOH treatment primarily degraded hemicelluloses with limited delignification. • More open cell wall structure and split of microfibrils improved glucose yield. • Block lignin by BSA further enhanced enzymatic hydrolysis with reduced enzyme dosage. Abstract A cost efficient synergistic strategy combining mild alkaline pretreatment (0.5–5% NaOH at 70 °C for 60 min) and bovine serum albumin (BSA) blocking of lignin was evaluated for effective conversion of poplar. The highest glucose yield of 69.2% was obtained for 5% alkaline pretreated sample, which was 4.4 times that of untreated sample. The enhanced enzymatic hydrolysis was attributed to significant hemicelluloses removal with limited delignification. Delignification mainly occurred in secondary wall, leading to more open cell wall structure, thus facilitating better transport of enzyme. Hemicelluloses removal helped split adjacent microfibrils, thus increased the specific sites for cellulase binding. After BSA addition in enzymatic hydrolysis, cellulose conversion further improved to 78.4% with 33% reduction of cellulase dosage due to decreased non-specific adsorption of cellulase on residual lignin. The utilization of synergistic alkaline pretreatment – BSA strategy may improve the overall economics of biomass conversion and successful commercial implementation of biorefineries. [ABSTRACT FROM AUTHOR]

[Display omitted] • The recycle times of [DBUH][CH 3 OCH 2 COO] (10 cycles) was twice of AmimCl. • The thermochemical stability: [DBUH][CH 3 OCH 2 COO] > AmimCl > [DBUH][CH 3 CH 2 OCH 2 COO]. • [DBUH][CH 3 OCH 2 COO] had high energy gap and low tendency of nucleophilic reaction. • High-performance regenerated cellulose was gained from recycled [DBUH][CH 3 OCH 2 COO]. The recyclability of superbase-derived ionic liquids (SILs) as a green and efficient solvent is considered to be an urgent and crucial issue to increase the economic viability of regenerated cellulose (RC) processing. Herein, two novel 1,8-diazabicyclo[5.4.0]undec-7-enium carboxylates ([DBUH][CH 3 OCH 2 COO] and [DBUH][CH 3 CH 2 OCH 2 COO]) were first recovered from the coagulation bath in the cellulose regeneration, as compared to traditional 1-allyl-3-methylimidazaolium chloride (AmimCl). The degradation mechanism of ionic liquids (ILs) in the recovery process and the properties of RC prepared from recycled ILs were analyzed to investigate the solvent availability. The results indicated that the average recovery yields of the three ILs were achieved up to 95–97 % without any further process optimisation. The highest recycle times of [DBUH][CH 3 OCH 2 COO] (10 times) with the outstandingly thermochemical stability was obtained in the recovery process, which was twice of AmimCl (5 cycles). It can be explained that [DBUH][CH 3 OCH 2 COO] exhibited the highest energy gap, the lowest electrophilicity index, and the weakest tendency to nucleophilic reaction with water. Conversely, [DBUH][CH 3 CH 2 OCH 2 COO] was only recovered for 4 cycles because of the active conjugation state between [DBUH]+ and [CH 3 CH 2 OCH 2 COO]−, in especial the strong electron-donating capacity of –OCH 2 CH 3. The C N in [DBUH][CH 3 CH 2 OCH 2 COO] was prone to nucleophilic attack by water to increase the degradation degree. Furthermore, the RC obtained from recycled [DBUH][CH 3 OCH 2 COO] possessed higher crystallinity and thermal stability in comparison with that from recycled AmimCl, which was corresponding to the recyclability of ILs. These findings favor [DBUH][CH 3 OCH 2 COO] as a promising solvent in the scaling up of the cellulose processing and utilization. [ABSTRACT FROM AUTHOR]

Highly efficient breaking lignocellulose cell wall recalcitrance towards biomass valorization still remains a great challenge. In this work, we developed a very effective lignin-first strategy using diols for direct fractionation of light-color lignin, and resulting in enhancement of enzymatic saccharification of cellulose-rich residues. The isolated lignin fraction possessed relatively higher content of β-O-4 linkages (26.6%), purity (>99%) and yield (>50%) and its brightness reached 22.0%ISO, which was 15.3, 13.5 and 1.9 folds higher than Kraft lignin, lignosulfonate and alkali lignin, respectively. In addition, the obtained nearly white-color lignin could be efficiently and directionally depolymerized into syringyl type phenols with high yields (82.0% of total phenols). Enzymatic hydrolysis efficiency of cellulose-rich residues was significantly enhanced up to 84.95% due to the more effective adsorption of cellulase under this diols strategy. Overall, the developed lignin-first strategy showed noteworthy preponderance on overcoming cell wall recalcitrance to achieve the whole lignocellulosic components valorization. [Display omitted] ● Nearly white lignin was fractionated directly by an effective lignin-first strategy. ● The brightness of the obtained lignin was much higher than industrial lignin. ● 1,4-butanediol reacted with carbocation of lignin to form α-etherified structure. ● Cellulose saccharification was significantly enhanced to 84.95% via this strategy. [ABSTRACT FROM AUTHOR]

Background: The natural recalcitrance of lignocellulosic plant cell walls resulting from complex arrangement and distribution of heterogeneous components impedes deconstruction of such cell walls. Dilute acid pretreatment (DAP) is an attractive method to overcome the recalcitrant barriers for rendering enzymatic conversion of polysaccharides. In this study, the internodes of Miscanthus × giganteus, a model bioenergy crop, were subjected to DAP to yield a range of samples with altered cell wall structure and chemistry. The consequent morphological and compositional changes and their possible impact on saccharification efficiency were comprehensively investigated. The use of a series of microscopic and microspectroscopic techniques including fluorescence microscopy (FM), transmission electron microscopy (TEM) and confocal Raman microscopy (CRM)) enabled correlative cell wall structural and chemical information to be obtained. Results: DAP of M. × giganteus resulted in solubilization of arabinoxylan and cross-linking hydroxycinnamic acids in a temperature-dependent manner. The optimized pretreatment (1% H2SO4, 170°C for 30 min) resulted in significant enhancement in the saccharification efficiency (51.20%) of treated samples in 72 h, which amounted to 4.4- fold increase in sugar yield over untreated samples (11.80%). The remarkable improvement could be correlated to a sequence of changes occurring in plant cell walls due to their pretreatment-induced deconstruction, namely, loss in the matrix between neighboring cell walls, selective removal of hemicelluloses, redistribution of phenolic polymers and increased exposure of cellulose. The consequently occurred changes in inner cell wall structure including damaging, increase of porosity and loss of mechanical resistance were also found to enhance enzyme access to cellulose and further sugar yield. Conclusions: DAP is a highly effective process for improving bioconversion of cellulose to glucose by breaking down the rigidity and resistance of cell walls. The combination of the most relevant microscopic and microanalytical techniques employed in this work provided information crucial for evaluating the influence of anatomical and compositional changes on enhanced enzymatic digestibility. [ABSTRACT FROM AUTHOR]

Compression wood represents a unique challenge for biochemical processing of sustainable biomass to produce biofuels and bioproducts on account of its highly lignified tracheids relative to opposite wood. In the current work, differentiating response of Pinus bungeana Zucc. compression wood and opposite wood tracheid walls to dilute acid pretreatment was elucidated by combining chemical and microscopic approaches. Dilute acid pretreatment released greater amount of hemicelluloses from opposite wood (91.0%) than from compression wood (31.2%). The dissolution of hemicelluloses was not uniform and varied across the tracheid wall. In addition, for both compression wood and opposite wood the heterogeneity in lignin distribution was enhanced, probably attributed to the lignin migration and relocalization. The ultrastructural arrangement of the cell wall was also altered with the pretreated opposite wood tracheid wall exposing more apparent cellulose microfibril bundles and less abundant globular structures compared to compression wood. The dilute acid pretreatment demonstrated that the greater recalcitrance of compression wood probably originated from the higher lignin content and the resulting more compact structure of the cell wall. [ABSTRACT FROM AUTHOR]

• The colorimetric sensing films were fabricated with cellulose and naphthoquinone dyes extracted from Arnebia euchroma (AENDs). • The AENDs solution showed a clear colorimetric change from rose red to dark blue at pH range of 5–12. • The films have excellent mechanical and hydrophobic properties. • The color change of the film correlated well with TVBN and total viable count (TVC) content of shrimp and pork during spoilage. During recent years the use of smart colorimetric packaging films for monitoring food freshness has received widespread attention. However, their poor mechanical strength and hydrophilic properties are the major problems hindering the large-scale application. Here, we employed biodegradable cellulose and naphthoquinone dyes extracted from Arnebia euchroma (AENDs) to fabricate a novel colorimetric sensing film with high tensile strength of 227 MPa and hydrophobic properties (water contact angle of 112.2°) for real-time monitoring of the freshness of shrimp and pork. In addition, the effectiveness of the sensing film in detecting the freshness of shrimp and pork under 20 °C, 4 °C and-20 °C conditions was confirmed by measuring the total volatile basic nitrogen (TVBN) and total viable count (TVC). Visual observation confirmed that the sensing film clearly changed from rose-red to purple, then to bluish violet providing a good indication of spoilage, which correlated well with TVBN and TVC content in shrimp and pork measures by standard lab procedures. The colorimetric sensing film developed here would be promising in fabricating high mechanical strength and hydrophobic properties smart labels for visual monitoring the freshness of shrimp and pork. [ABSTRACT FROM AUTHOR]

• RC membranes with high tensile strength and antibacterial property were fabricated. • The grafted membrane had a high mechanical strength of 65.2–93.5 MPa. • The bacteria killing ratio of RC-12% TMSPED membranes reached 99.9%. • Methoxy, amino and alkyl quantity strongly affected antibacterial activity. There is a growing interest in preparing membrane materials particularly with antibacterial surface and high mechanical strength from natural resources. In this work, to fabricate cellulose membrane with high tensile strength and antibacterial property, surface amination of regenerated cellulose (RC) membranes were studied. Four aminosilanes at different concentrations and the effects of alkoxyl quantity, alkoxyl chain length, and aminoalkyl chain length of aminosilanes on membrane performance were explored. The results indicated that all membranes were successfully grafted by aminosilanes with different grafting yield. The grafted RC membranes had high mechanical strength of 65.2–93.5 MPa with high hydrophobicity and thermal stability. Among aminosilanes-varying treatments, RC membranes grafted by 12% of N -[3-(trimethoxysilyl) propyl] ethylenediamine (TMSPED) which had three methoxy groups, the highest amount of amino groups, and the longest chain of aminoalkyl were demonstrated to be the most effective against Gram-positive bacteria. The bacteria killing ratio increased with improving amino content and reached almost 100%. The prepared colorless RC membranes with high tensile strength, high thermal stability, and enhanced antibacterial properties may provide more opportunities for further advancement and applications in active packaging. [ABSTRACT FROM AUTHOR]

• A high-efficiency bifunctional organocatalyst was explored to produce furfural. • The potential catalytic mechanism was first proposed. • The highest furfural yield was 70.19% from xylose under optimized conditions. • 92.19% furfural yield was achieved from tung shell in this catalytic system. A bifunctional solid organocatalyst, sulfamic acid, was evaluated to produce furfural from xylose and different biomass in an environmentally friendly system comprising Gamma-Valerolactone (GVL) and water. The highest yield (70.19%) of furfural was achieved in a 90% solution of GVL in water containing 10 mol% of sulfamic acid at 190 °C for 15 min from xylose. The potential mechanism of sulfamic acid efficiently catalyzing xylose isomerization and dehydration is presented for the first time. It is hypothesized that another sulfamic acid form, the zwitterionic unit (H 3 N+SO 3 −) is crucial in efficiently catalyzing isomerization reaction due to its electron-rich sulfonate being superior in attacking the hydrogen atom on C1 leading to the xylose tautomerization to xylulose, a shorter route to furfural, and finally, the NH 2 SO 3 H with strong acidity also promotes the xylulose dehydration to furfural. The above system was evaluated using various biomass species including corncob, Miscanthus × giganteus , the hull and shell of Camellia oleifera (tea) fruit and Aleurites fordii HemsL. (tung) fruit. Almost all these biomass showed excellent furfural yields (over 70%), with tung shell providing the best yield of 92.19% at 200 °C and reaction time of 30 min. [ABSTRACT FROM AUTHOR]