Wet Jet Research Articles

Mannan-rich Holocellulose nanofibers mechanically isolated from spent coffee grounds: Structure and properties

Spent coffee grounds (SCGs) contain abundant polysaccharides consisting of mannose (29 %), galactose (11 %), and glucose (11 %) and are a promising source of holocellulose nanofibers (HCNFs). In this study, the mannan-rich HCNFs were isolated from the SCG holocellulose in the yield of 52 % SCGs using an ultrahigh-pressure wet jet mill. The HCNF was refined by passing the suspension through a high-pressure homogenizer with a 95 μm nozzle 1–15 times. The 5-pass HCNFs were 2.4 nm wide and 0.7 μm long with 143 viscosity-average degrees of polymerization and contained mannan I crystals (5–10 nm in size) on cellulose microfibrils. The delignification process in water at 75 °C based on the Wise method allowed recrystallization of mannan on a cellulose microfibril substrate. The once-freeze-dried HCNFs had 30–50 nm widths and were not fully nanofibrillated in water when shaking the HCNF/water suspensions but exhibited comparable viscosities to those prepared by mechanical milling. The SCGs-derived HCNFs have a high potential for application in the food industry.

Bayesian Optimization of Environmentally Sustainable Graphene Inks Produced by Wet Jet Milling.

Liquid phase exfoliation (LPE) of graphene is a potentially scalable method to produce conductive graphene inks for printed electronic applications. Among LPE methods, wet jet milling (WJM) is an emerging approach that uses high-speed, turbulent flow to exfoliate graphene nanoplatelets from graphite in a continuous flow manner. Unlike prior WJM work based on toxic, high-boiling-point solvents such as n-methyl-2-pyrollidone (NMP), this study uses the environmentally friendly solvent ethanol and the polymer stabilizer ethyl cellulose (EC). Bayesian optimization and iterative batch sampling are employed to guide the exploration of the experimental phase space (namely, concentrations of graphite and EC in ethanol) in order to identify the Pareto frontier that simultaneously optimizes three performance criteria (graphene yield, conversion rate, and film conductivity). This data-driven strategy identifies vastly different optimal WJM conditions compared to literature precedent, including an optimal loading of 15wt% graphite in ethanol compared to 1wt% graphite in NMP. These WJM conditions provide superlative graphene production rates of 3.2ghr-1 with the resulting graphene nanoplatelets being suitable for screen-printed micro-supercapacitors. Finally, life cycle assessment reveals that ethanol-based WJM graphene exfoliation presents distinct environmental sustainability advantages for greenhouse gas emissions, fossil fuel consumption, and toxicity.

Enzymatic Characterization of Unused Biomass Degradation Using the Clostridium cellulovorans Cellulosome.

The cellulolytic system of Clostridium cellulovorans mainly consisting of a cellulosome that synergistically collaborates with non-complexed enzymes was investigated using cellulosic biomass. The cellulosomes were isolated from the culture supernatants with shredded paper, rice straw and sugarcane bagasse using crystalline cellulose. Enzyme solutions, including the cellulosome fractions, were analyzed by SDS-PAGE and Western blot using an anti-CbpA antibody. As a result, C. cellulovorans was able to completely degrade shredded paper for 9 days and to be continuously cultivated by the addition of new culture medium containing shredded paper, indicating, through TLC analysis, that its degradative products were glucose and cellobiose. Regarding the rice straw and sugarcane bagasse, while the degradative activity of rice straw was most active using the cellulosome in the culture supernatant of rice straw medium, that of sugarcane bagasse was most active using the cellulosome from the supernatant of cellobiose medium. Based on these results, no alcohols were found when C. acetobutylicum was cultivated in the absence of C. cellulovorans as it cannot degrade the cellulose. While 1.5 mM of ethanol was produced with C. cellulovorans cultivation, both n-butanol (1.67 mM) and ethanol (1.89 mM) were detected with the cocultivation of C. cellulovorans and C. acetobutylicum. Regarding the enzymatic activity evaluation against rice straw and sugarcane bagasse, the rice straw cellulosome fraction was the most active when compared against rice straw. Furthermore, since we attempted to choose reaction conditions more efficiently for the degradation of sugarcane bagasse, a wet jet milling device together with L-cysteine as a reducing agent was used. As a result, we found that the degradation activity was almost twice as high with 10 mM L-cysteine compared with without it. These results will provide new insights for biomass utilization.

Dispersion process of highly crystalline single-walled carbon nanotubes focusing on their chemical stability

The purpose of this study is to develop a planar field electron emission source that can be driven stably for a long time with low energy consumption and output power control to realize field-emission–cathodoluminescence (CL) devices with excellent energy efficiency. This was achieved driven by the motivation that the use of CLs with excellent quantum efficiency can create new values for society by realizing energy-saving lighting. We attempted to prepare dispersion coatings of highly crystalline single-walled carbon nanotubes (hc-SWCNTs) with guaranteed chemical stability by an industrial dispersion process. The change in chemical stability owing to the adoption of the dispersion process was traced by quantifying the shape of the thermogravimetric analysis (TGA) curve, and the process suitable for the dispersion of hc-SWCNTs was investigated. As a result, it was shown that the wet jet mill dispersion process could be combined to achieve dispersion with slightly deteriorated chemical stability. This was achieved by reducing the milling effect of foreign matter and by controlling the shear force and the number of shear cycles applied to the dispersion.

Asian monsoon projection with a new large-scale monsoon definition

This paper focuses on Asian monsoon projection with CMIP5 multi-model outputs. A large-scale monsoon herewith is defined as a vector field of vertically integrated moisture flux from the surface to 500 hPa. Results demonstrate that the model ensemble mean underestimated the summer monsoon and overestimated slightly the winter monsoon over South Asia in both CMIP5 historical climate simulation and the monsoon projection for 2006–2015. The major of the bias is the model climate drift (MCD), which is removed in the monsoon projection for 2016–2045 under scenarios RCP4.5 for reducing the uncertainty. The projection shows that two increased moisture flows northward appeared across the Equator of Indian Ocean, the first is nearby Somalia coast toward northwestern part of South Asia, leading to excess rainfall in where the wet jet could reach, and the second starts from the equatorial Sect. (80°E–100°E) toward northeastern Bay of Bengal, leading to more rainfall spreading over the northwestern coast of Indochina Peninsula. In addition, a westward monsoon flow is intensified over the Peninsula leading to local climate moisture transport belt shifted onto South China Sea, which would reduce moisture transport toward Southwest China on one hand, and transport more moisture onto the southeast coast of the China mainland. The anomalous monsoon would result in a dry climate in Northwest China and wet climate in the coast belt during summer monsoon season for the period. Besides, the Asian winter monsoon would be seemingly intensified slightly over South Asia, which would bring a dry winter climate to Indian subcontinent, Northwest China, but would be more rainfall in southeast part of Arabian Peninsula with global climate warming.

Chitin extracted from various biomass sources: It's not the same

This study demonstrates the use of ionic liquids to successfully extract chitin from different biomass sources and the utilization of the resulting chitins to prepare monofilament fibers. Chitin was extracted from five different biomass sources (processed and raw shrimp shell, crab and lobster shell, and fly larvae) using the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]). While processed and raw shrimp shell yielded chitin of high purity in quantitative yield, crab and lobster shell resulted in lower yields of chitin. Fly larva provided chitin severely contaminated with proteins. Each extracted chitin was re-dissolved in the same IL and dry wet jet spun into monofilament fibers to determine any trends in mechanical properties vs. biomass source. The concentration needed to spin fibers was not consistent and had to be adjusted individually for each type of chitin obtained. Chitin from raw shrimp shell produced the strongest fibers, while the chitin from the crab and lobster produced weaker fibers, although, the latter were twice as elastic. The use of fly larvae led to the weakest and least elastic fibers.

Experimental study on temperature drop during roller quenching process of large-section ultra-heavy steel plate.

Large-section ultra-heavy steel plates feature low cooling rate of central part during quenching process, as well as great differences in texture and performance along thickness direction. Wet jet impingement quenching test apparatus and multi-channel temperature recorder were developed to explore the temperature drop characteristics and its influential factors of ultra-heavy steel plate. The temperature drop curves of plates with different thickness (160, 220, and 300 mm) and weight (23-43 tons) were recorded during the quenching process, accompanied with the exploration on distribution rules of temperature gradient, heat flux density and cooling rate along thickness direction under different water volumes (9000-9400 m3/h) and pressures (0.4-0.8 MPa), upon which the three-dimensional inverse heat conduction model, surface heat transfer coefficient model and thermophysical parameter model were established using finite element and optimization methods. The overall results indicate the symmetric heat transfer between the upper and lower plate surfaces can be realized, when the water flow ratios of the upper and lower surfaces were 1:1.25 and 1:1.4 under pressures of 0.8 MPa and 0.4 MPa, respectively. The "temperature return" phenomenon was accompanied with changing heat flux density of wall surface of 220 mm- and 300 mm-thick plates. The lowest cooling rate along thickness direction appeared at 1/4 thickness position for the 160 mm- and 220 mm- thick plates during quenching, which was attributable to the synergy between heat flux density and temperature gradient. This work may pave a way for improving the cooling rate and quenching uniformity of ultra-heavy steel plates along thickness direction.

Synthesis of layered silicon-graphene hetero-structures by wet jet milling for high capacity anodes in Li-ion batteries

While silicon-based negative electrode materials have been extensively studied, to develop high capacity lithium-ion batteries (LIBs), implementing a large-scale production method that can be easily transferred to industry, has been a crucial challenge. Here, a scalable wet-jet milling method was developed to prepare a silicon-graphene hybrid material to be used as negative electrode in LIBs. This synthesized composite, when used as an anode in lithium cells, demonstrated high Li ion storage capacity, long cycling stability and high-rate capability. In particular, the electrode exhibited a reversible discharge capacity exceeding 1763 mAh g−1 after 450 cycles with a capacity retention of 98% and a coulombic efficiency of 99.85% (with a current density of 358 mA g−1). This significantly supersedes the performance of a Si-dominant electrode structures. The capacity fade rate after 450 cycles was only 0.005% per cycle in the 0.05–1 V range. This superior electrochemical performance is ascribed to the highly layered, silicon-graphene porous structure, as investigated via focused ion beam in conjunction with scanning electron microscopy tomography. The hybrid electrode could retain 89% of its porosity (under a current density of 358 mA g−1) after 200 cycles compared with only 35% in a Si-dominant electrode. Moreover, this morphology can not only accommodate the large volume strains from active silicon particles, but also maintains robust electrical connectivity. This confers faster transportation of electrons and ions with significant permeation of electrolyte within the electrode. Physicochemical characterisations were performed to further correlate the electrochemical performance with the microstructural dynamics. The excellent performance of the hybrid material along with the scalability of the synthesizing process is a step forward to realize high capacity/energy density LIBs for multiple device applications.

Simultaneous attainment of particle dispersion and surface modification of Al2O3nanoparticles via wet–jet milling

The good dispersion and chemical modification of alumina (Al2O3) nanoparticles as filler were simultaneously performed by a wet–jet milling (WJM) process to disperse the nanoparticles effectively in the polymeric composite. The grafting densities of Al2O3nanoparticles silane–coupling modified by WJM increased from 0.73 to 1.84 molecules/nm2in hexyltriethoxysilane, and from 0.65 to 1.09 molecules/nm2in 3–glycidoxypropyltriethoxysilane. Furthermore, the Al2O3nanoparticles were dispersed to the primary particle size. In addition, the mechanical properties of the Al2O3/epoxy composite prepared by the in–situ mixing process were higher than those prepared by conventional dry mixing process. As results, the mechanical properties of the Al2O3/epoxy composite could be improved by optimizing the dispersion, chemical modification of the nanoparticles and mixing process of nanoparticles and polymer.

High-Sulfur-Content Graphene-Based Composite through Ethanol Evaporation for High-Energy Lithium-Sulfur Battery.

Lithium-sulfur batteries are the most promising candidates for next-generation energy storage devices owing to their high theoretical specific capacity of 1675 mAh g-1 and high theoretical energy density of approximately 3500 Wh kg-1 . However, the lack of cathode active materials with appropriate electrical conductivities and stability coupled with an inexpensive and industrially compatible production process has so far hindered the development of practical devices. Here, a facile preparation pathway is reported for the production of a sulfur-carbon composite active material by drying a mixture of highly conductive few-layer graphene (FLG) flakes (produced by exploiting an innovative wet jet milling process with a yield of ≈100 % and production capability of ≈23.5 g h-1 ) with elemental sulfur, using ethanol as an environmentally friendly solvent. The designed sulfur-FLG composite shows excellent electrochemical results. The assembled lithium-sulfur battery exhibits a stable rate capability up to a current rate of 2C, a coulombic efficiency approaching 100 % for 300 cycles at the current rate of C/4 (420 mA g-1 ), and a long cycle life up to 500 cycles delivering around 600 mAh g-1 at 2C (3350 mA g-1 ).

Composite Fibers From Cellulose Solutions with Additives of Bis (Trimethylsilyl) Acetylene and Alkoxysilanes: Rheology, Structure and Properties

Solid–state dissolution in N–methylmorpholine N–oxide was used to obtain solutions of mixtures derived from cellulose and various organosilicon additives, namely, tetraethoxysilane, vinyltriethoxysilane, and bis (trimethylsilyl)acetylene. Optical study of the phase composition and morphology of these solutions showed that they are two–phase emulsions with a rather broad size distribution of particles of the dispersed phase. The nature of the flow of the mixed systems in continuous and dynamic deformation when the rheological behavior is monotypic depends to a certain extent on the nature of the organosilicon additive. Dry wet–jet spinning was used to obtain composite fibers. The structure and morphology of these fibers were studied as well as their mechanical and thermal properties. Analysis of the x–ray patterns diffractograms of the cellulose and composite fibers showed that the introduction of organosilicon additives into the cellulose matrix leads to less structural ordering of the cellulose. The mechanical characteristics of the composite fibers show some decrease in the strength and deformation characteristics with an increase in the elastic modulus in comparison with the cellulose fibers. Heat treatment of the cellulose and composite fibers up to 1000°C revealed a significant increase in the mass of carbon residue, whose amount depends on the type of additive.

High‐Throughput Dimensional Evaluation of Hexagonal Boron Nitride 2D Nanomaterials

AbstractExfoliation of layered materials is a key to obtaining high‐performance 2D nanomaterials. Rapid and inexpensive exfoliation methods of the layered materials have been proposed recently. Along with the development, high‐throughput dimensional evaluation methods for the 2D nanomaterials are required as well. A novel method of dimensional evaluation for 2D nanomaterials is evolved. That can be characterized by utilization of synchrotron X‐ray powder diffraction. A bulky amount of hexagonal boron nitride (h‐BN) particles in solvents via wet jet milling is exfoliated and h‐BN 2D nanomaterials in plenty is obtained. Employing the resultant h‐BN 2D nanomaterials as measurement specimens, validity of the dimensional evaluation method is verified. With the powerful characterization method at hand, it is expected that optimization of various exfoliation processes will flourish in the near term.

Antifungal Composite Fibers Based on Cellulose and Betulin

Composite fibers and films based on cellulose and betulin were spun for the first time from solutions in N-methylmorpholine-N-oxide using the dry–wet jet method. The rheological properties of the composite solutions did not reveal any fundamental difference from those of the cellulose solutions. Introduction of betulin into the cellulose matrix (up to 10%) led to a decrease in the mechanical properties of the obtained fibers. The structure of the composite fibers was analyzed using SEM and X-ray diffraction methods. It was shown that the introduction of an additive into the cellulose matrix led to a decrease in the structural ordering of the cellulose. Comparative studies of the antibacterial activity of the composite films on Escherichia coli (E. coli) were carried out. The antifungal activity of the composite films was estimated using the strain of the O-97 Trichoderma viride Pers ex Fr (Gause Institute of New Antibiotics, Moscow, Russia).

The influence of support structures on cell immobilization and acetone–butanol–ethanol (ABE) fermentation performance

Cell immobilization is an efficient technique for achieving high-cell density; it has been shown to benefit acetone–butanol–ethanol (ABE) fermentation. In this study, the biodegradable material, poly(3-hydroxybutyrate) (PHB), was fabricated into plate-like structures by solvent casting (SC) and into fibrous structures by wet jet (WJ) and electrospinning (ES). The BET data showed that the specific surface areas of PHBSC, PHBWJ, and PHBES were 0.17, 18.30, and 22.45m2/g, respectively. Butanol yields of 0.25±0.04, 0.28±0.01, and 0.20±0.01g-butanol/g-glucose were obtained for PHBSC, PHBWJ, and PHBES during batch ABE fermentation. OD600 of fermentation broths that contain PHBSC, PHBWJ, and PHBES can be used to evaluate the immobilization ability. It was found that while OD600 of fermentation broths without an immobilization material was 12.0±1.6, OD600 of fermentation broths containing PHBWJ was 4.3±0.3, which was the best for the three PHB materials tested. In summary, a high specific surface area with a pore size up to several hundred microns is recommended. The robustness and stability of PHB as an immobilization material for ABE fermentation was clearly confirmed.

Enyzyme-Immobilized Electrode Prepared Using Cellulose Nanofiber

Various procedures have been proposed for the preparation of enzyme-immobilized electrode, such as covalent attachment, cross-linking, hydrogel entrapment, polymer film entrapment, and the combination of two or more methods.Cellulose is a linear polysaccharide of glucose, which have significant high strength and stability due to strong intra- and inter-molecular hydrogen bonds within and among individual chains. Cellulose nanofiber (CNF) dispersion solution can be obtained by stripping down water insoluble cellulose fibers using procedures such as wet jet milling. In this study, CNF was applied for the immobilization of enzyme by entrapping it within CNF matrix. Glucose oxidase (GOx) was employed as the enzyme, and GOx-CNF immobilized electrodes were fabricated by simple repetitious drops of cellulose solution containing GOx on the surface of an electrode. The obtained electrode provided a glucose sensor with significantly high response speed and good linear relationship between glucose concentration and response current. Introduction of CNF films on GOx-CNF film successfully reduced the release of GOx from enzyme-immobilized electrode and glucose sensor with good long term stability was obtained.

Fabrication of Amperometric Glucose Sensor Using Glucose Oxidase-Cellulose Nanofiber Aqueous Solution.

Cellulose nanofiber aqueous solution, which remained virtually transparent for more than one week, was prepared by using the clear upper layer of diluted cellulose nanofiber solution produced by wet jet milling. Glucose oxidase (GOx) was easily dissolved in this solution and GOx-immobilized electrode was easily fabricated by simple repetitious drops of GOx-cellulose solution on the surface of a platinum-iridium electrode. Glucose sensor properties of the obtained electrodes were examined in phosphate buffer solution of pH 7.4 at 40°C. The obtained electrode provided a glucose sensor response with significantly high response speed and good linear relationship between glucose concentration and response current. After an initial decrease of response sensitivity for a few days, relatively constant sensitivity was obtained for about 20 days. Nevertheless, the influence of electroactive compounds such as ascorbic acid, uric acid and acetoaminophen were not negletable.

Influence of kneading time on network formation and electrical properties of wet jet milling treated and untreated SWCNT reinforced polyamide 6 nanocomposites by impedance spectroscopy

Kneading time effect on electrical properties of SWCNT reinforced polyamide 6 (SWCNT/PA6) nanocomposites was investigated in detail by impedance spectroscopy. In-situ polymerization method was applied for sample preparation. As received (AR) and wet jet milling (WJM) method treated SWCNTs were both used as two kinds of fillers. IS results indicated that the electrical conductivity in both AR-SWCNT/PA6 and WJM-SWCNT/PA6 nanocomposites can get an improvement under suitable kneading treatment, but with longer kneading time, the dielectric property would be enhanced. Moreover, IS results showed that WJM-SWCNT/PA6 nanocomposites had a higher electrical conductivity (6.5 × 10−2 S/m) than AR-SWCNT/PA6 nanocomposites (1.9 × 10−2 S/m), which has been attributed to be from different network distribution state of AR-SWCNTs and WJM-SWCNTs. This study indicates that electrical and dielectric properties of CNT based polymer nanocomposites can be effectively controlled by adjusting kneading time, and lower percolation threshold could be potentially achieved by suitable kneading time and morphology treatment of CNTs.

Preparation of Glucose Oxidase-Immobilized Electrodes Using Cellulose Aqueous Solution

Nearly transparent cellulose aqueous solution was prepared using the clear layer of diluted cellulose dispersion solution produced by wet jet milling. Glucose oxidase (GOx) was immobilized on platinum-iridium electrode by applying certain amount of cellulose aqueous solution containing GOx and dried for at least two days in room temperature. The obtained GOx-immobilized electrodes provided good response current up to 22.4 mM. Good linear relationship between glucose concentration and response current was observed. Correlation coefficient of 0.994 was obtained ranging from 0 to 11 mM on the electrode prepared using 500 mg/L cellulose and 250 mg/L GOx mixture solution. The sensor response was significantly fast and steady state current was obtained within one second. The stability of GOx-immobilized electrode response was measured for 30 days. After initial decrease of response current for the first few days, relatively constant responses were obtained for twenty days.

カーボンナノチューブやセルロースナノ ファイバーの湿式分散・解繊技術

The water jet is a method widely used for the washing and deburring, cutting, milling of various parts. Star Burst System (SBS) developed by Sugino Machine Limited is atomization machine that uses a water jet. SBS is capable to pressurize slurry containing raw material up to 245 MPa. Slurries are ejected from two opposed nozzles and collide in the chamber. Raw material in the slurry is atomized and becomes very small. In this paper, the results of wet jet treatment by SBS for carbon nanotube and cellulose are introduced. Carbon nanotube treated by water jet was homogeneously dispersed in water, and median size was about 2 orders of magnitude smaller than untreated sample. Cellulose treated alike was gel-like form, and became nanofiber having diameters ranging from 20 to 50 nm.

Experimental Investigation of Abrasive Jet Polishing on the Free-Form Machined Surfaces of SKD61 Mold Steel Using SiC Particles

This study performs an experimental investigation into the wet abrasive jet polishing (AJP) of three different SKD61 specimens, namely, a linear microgroove, a linear microchannel, and a curved microchannel. It is shown that when the polishing process is performed using #3000SiC particles, the surface roughness (Rmax) of the SKD61 microgroove is reduced from 2.32 µm to 0.40 µm within 30 min. Furthermore, when using #1000SiC particles and a vacuum suction pressure of 60 cmHg (0.82 kg/cm2), the surface roughness of the linear microchannel is reduced from 3.45 µm to 0.43 µm within 60 min, while that of the curved microchannel is reduced from 3.58 µm to 0.45 µm. Overall, the experimental results show that the wet AJP method provides a quick and efficient means of removing the milling traces from SKD61 mold steel components to leave a mirror-like polished surface.