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Cellulose nanocrystals (CNCs) are biobased materials with many desirable properties such as high aspect ratio, mechanical strength, crystalline nature, and biodegradability. This study developed a commercial-scale process model of CNC production from wood pulp using sulfuric acid treatment and evaluated its techno-economic and environmental performance with and without acid recovery. The results indicated that CNC produced with acid recovery process was financially more profitable with higher project net present values than without acid recovery process but required higher capital which resulted in a longer payback period and lower return on invested capital. The estimated minimum selling prices of CNC produced with and without acid recovery were $4.69/kg and $4.89/kg, respectively. The global warming (GW) impacts of 1 kg CNC production with and without acid recovery were 11.39 and 11.18 kgCO 2 eq, respectively, showing that higher steam use and consequently more fossil fuels were needed in the acid recovery process., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

A two-stage reaction system was developed to synthesize butyl levulinate (BL), a derivative chemical of levulinic acid, from agricultural residue (rice straw). A single reactor was employed during the first processing stage for the conversion of rice straw cellulose to levulinic acid (LA) in a novel co-solvent system consisting of dilute phosphoric acid and tetrahydrofuran. The highest yield of 10.8% wt. LA concentration (i.e., ∼42% of theoretical LA yield) with intermediate residuals concentration of 1.5% wt. glucose and 0.5% wt. 5-hydroxymethylfurfural (5-HMF) on dry weight basis of biomass was obtained at modest reaction conditions. During subsequent esterification reaction, approximately 7.8% wt. BL yield (at 89% conversion yield) was achieved from the solvent extracted precipitate containing majorly LA and residual 5-HMF in the presence of 0.5M sulfuric acid using n-butanol. Based on comparative esterification results obtained using commercial chemicals (LA and 5-HMF), apparently 5-HMF exhibited ∼8% wt. BL yield through direct synthesis in the presence of sulfuric acid using n-butanol under the same specified reaction conditions. Alongside, effectiveness of co-solvent treatment on rice straw for potential fermentable sugar release (glucose) was investigated by subjecting the respective post-reaction solid residues to enzymatic digestion using cellulase and yielded highest of 11% wt. per wt. solids (27% wt. glucose conversion efficiency), amongst solid residues underwent different processing conditions., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Model compounds and recalcitrant biomass were studied to elucidate the mechanism of ambient-temperature acid pretreatment of cellulosic biomass for bio-ethanol production. Pure cellulose, a pure hemicellulose and alfalfa stems were pretreated with sulfuric acid under ambient temperature with varied acid loading and time. Changes in water-soluble carbohydrates (WSCs) and chemical components of substrates were determined, and ethanol production via simultaneous saccharification and fermentation (SSF) was studied. The results showed significant amount of WSCs formed, and the WSCs increased with increasing acid loading and pretreatment time. The ethanol yields from pure cellulose were primarily affected by the added ash. Acid loading showed significant positive effect on ethanol production from alfalfa stems, whereas pretreatment time showed much weaker positive effect. However, non-significant amounts of WSCs were removed by washing of dried substrates. It was hypothesized to be because the WSCs adsorbed onto bulk substrates during the freeze-drying step, as supported by experimental results., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

This study describes a multi-wavelength spectroscopic method for the determination of carboxyl group content of nanocellulose. Methylene blue (MB) was used as a color indicator, which can bind to the carboxyl groups in nanocellulose to form a R-COOMB complex with a binding ratio of 1:1, although the spectrums of MB and R-COOMB at 500–750 nm are overlapped, and solid impurities could cause spectral interference. To solve these issues, a multi-wavelength spectroscopic measurement on a MB and nanocellulose mixture solution technique and mathematical model were developed, allowing the content of carboxyl groups in nanocellulose to be quantified. The results showed that the method has good measurement precision and accuracy as compared with those measured by a reference method. The method is simple and requires only a small sample size for testing and thus makes it suitable for nanocellulose related research and applications. [ABSTRACT FROM AUTHOR]

Nanocellulose is conventionally produced from woody biomass including wood, crops and forest/agricultural residues, by top-down methods. Due to biomass recalcitrance, pretreatment, with a subsequent bleaching process, is mandatory to break down the resistance of the composite for nanocellulose extraction. In the present study, gamma-valerolactone (GVL) pulping without further bleaching/purification was used for producing cellulose nanomaterials from wood. GVL pulp and bleached kraft pulp from Aspen were comparatively studied as starting materials for (2,2,6,6-tetramethylpiperidin-1-yl)oxidanyl (TEMPO) cellulose nanofibril (TCNF) preparation. The TEMPO oxidation process and properties of the as-prepared TCNF solutions and films were studied to investigate the advantages of GVL pulp for TCNF production. There was no difference between nanocellulose prepared from GVL pulp and that from bleached kraft pulp. But, with the GVL pulping process, no subsequent bleaching process was required while the properties of the as-prepared nanocellulose were preserved. [ABSTRACT FROM AUTHOR]

Dairy manure containing partially digested plant cells is an inexpensive bioenergy feedstock. The carbohydrates and lignin that remain after digestion are typically processed in an anaerobic digester to produce biomethane, but due to the remaining material's recalcitrance, the process has a low conversion efficiency. To improve the conversion of this lignocellulosic material, chemical, thermal, or biological pretreatments can be considered. This study compared several chemical pretreatments including dilute acid, sulfite, and alkali pretreatments for dairy manure as a bioenergy feedstock and analyzed their impact on biomethane production. The comparative study showed that a hot alkali pretreatment (180 °C, 30 min) can improve the methane production of dairy manure by 50%, which is more effective than dilute acid (6.8%), sulfite (26.3%), and cold or ambient alkali (19.8 to 32.8%) pretreatments. However, the ambient alkali pretreatment (23 °C, 12 h) was calculated to be more economically feasible because of the net energy production. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]