Low Solid Loading Research Articles

Effect of sintering temperature on the microstructures and mechanical properties of ZrO2 ceramics fabricated by additive manufacturing

The optimization of the sintering process for ceramic stereolithography-based additive manufacturing is attracting high interest important due to its correlation with the final properties of the fabricated parts. In this work, a photosensitive zirconia suspension with low viscosity and high solid loading (48 vol%) was prepared using surface-modified zirconia ceramic powders, resulting in an improvement in long-term stability. The correlations between the sintering temperature (1400–1520 °C) and mechanical properties were investigated. The results showed that and the as-sintered zirconia parts exhibited a relatively high density of 99.5 ± 0.1 % and three-point flexural strength of 821 ± 65 MPa as well as excellent fracture toughness (4.37 ± 0.22 MPa m1/2) sintering at 1480 °C, which was attributed to the highly homogeneous microstructure without obvious pores or crack. The obtained insights regarding the correlation between sintering temperature, relative density, and flexural strength can provide practical guidance for the future applications of zirconia ceramics.

Hydrothermal carbonisation of mixed agri-food waste: Process optimisation and mechanistic evaluation of hydrochar inorganic chemistry

In this study, low-quality mixed agri-food waste (MAFW) was upgraded into homogenous high-quality solid fuel (i.e., hydrochar) via hydrothermal carbonisation (HTC). Response surface methodology (RSM) and principal component analysis (PCA) were used to study the effect of temperature (190–230 °C), residence time (1–5 h) and solid loading (5–20 %) on hydrochar fuel characteristics and provide mechanistic insights into hydrochar inorganic chemistry. In addition, HTC operating conditions were optimised to maximise hydrochar yield and calorific value and minimise ash content. Results from RSM revealed that reaction temperature and solid loading had most influence on the studied responses. The process optimisation of the HTC of MAFW resulted in hydrochar yield, calorific value and ash content of 52.25 %, 24.56 MJ/kg and 6.20 % (further validated within 3 % error), respectively at optimum operating condition of ⁓212 °C, 5 h and ⁓7.8 % solid loading. Furthermore, analysis by PCA revealed solid loading had a more significant impact on the fate of inorganic elements compared to reaction temperature and residence time. The results also suggests that inorganics are less concentrated in hydrochar at low solid loading and medium reaction severity. Compared to the raw-MAFW, the likelihood of fouling and slagging during combustion was reduced in the hydrochar.

Modeling pressure drop in curvature and reacceleration zones in bends during pneumatic conveying of fine powders

This paper presents the results of ongoing research aimed at modeling the pressure drop in bends during pneumatic conveying of fine powders. Based on the test results of conveying fly ash and two grades of cement through three different radii of curvature of the bends, two different bend diameters, and two different locations of the test bend, a semi-empirical relationship was developed for bend loss with various pressure drop components modeled separately. The newly developed model was used to predict the bend loss for a solid loading ratio in the range of 51–170 (very dense phase). The proposed model exhibited a satisfactory level of prediction accuracy, with relative error percentages of less than 12.2% and 19.6% for the high and low solids loading ratios, respectively.

Advanced Manufacturing of Unique Solid Oxide Fuel Cell Electrode and Electrolyte Microstructures through Aerosol Deposition

Development of various additive manufacturing technologies over the years has given an opportunity for highly customizable and unique structures to be fabricated with applications towards several different industries. For ceramic manufacturing, techniques such as direct ink writing (DIW), stereolithography (SLA), and fused deposition modeling (FDM) have been utilized to construct very complex structures. These technologies have also been developed for use towards solid oxide fuel cells (SOFCs) where they have been utilized to manufacture components greater than 200 µm in thickness. Some components of the SOFC such as the electrodes, electrolyte, and barrier layer are much smaller and consist of thicknesses from 1 µm to 50 µm. Along with the reduced thickness, the electrodes of a SOFC are often comprised of a composite material where the previously mentioned technologies struggle with achieving both the required high resolution and compositional change needed to manufacture these specific components. This project’s goal is to develop an additive manufacturing technique that suits both requirements for manufacturing the electrodes, electrolyte, and barrier layer of a SOFC.The technology that has been developed to complete the manufacturing of highly customizable electrodes along with the electrolyte and barrier layer is Aerosol Deposition. The Aerosol Deposition system contains several different elements that lead to consistently tailored microstructures for the various 3-D printed parts including the use of syringe pumps, an ultrasonic atomizing nozzle from Sonaer Ultrasonics, an infrared heater, and a flexible automation system. The ultrasonic atomizing nozzle is used to convert a stream of liquid into a fine mist via mechanical vibrations. The liquid that is supplied to our ultrasonic atomizing nozzle is low solids loading solvent-based suspension containing approximately 1 - 5 vol% of solids and polymer pore formers. Suspensions are supplied to the nozzle by mechanical pressure provided from a programmable syringe pump. This technology accompanied with a flexible automation system gives the potential for highly customizable and repeatable microstructures that can aid in evaluating variables associated with the different components of the SOFC.Development of the additive manufacturing system to fabricate the anode functional layer, electrolyte, barrier layer, and cathode active and current collector layers through an automated process have been studied. For the electrodes, a microstructure that contains approximately 30% - 40% porosity is suitable to enhance the electrochemical performance of the electrode. Sintering temperatures for the electrodes typically range from 1000 °C to 1300 °C which can typically densify the microstructure and restrict the amount of porosity present. To implement porosity within the microstructure poly(methyl methacrylate) was incorporated into electrode suspensions due to their ability to diffuse out of the electrode microstructure at temperatures of ~450 °C. The electrical and mechanical properties of the separate components have been characterized accordingly utilizing electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). Acknowledgements: This work was performed in support of the US Department of Energy’s Solid Oxide Fuel Cell Program. The authors would like to acknowledge the WVU Shared Research Facilities (SRF) and thank Dr. Thomas Kalapos from Leidos Research Support Team for his assistance.

High-Efficient Production of Cellulosic Ethanol from Corn Fiber Based on the Suitable C5/C6 Co-Fermentation Saccharomyces cerevisiae Strain

As a potential alternative to fossil-based fuels, cellulosic ethanol has attracted much attention due to its great benefit to energy sustainability and environmental friendliness. However, at present, the industrial competitiveness of cellulosic ethanol production is still insufficient compared with fossil-based fuels because of the higher costs. Expanding the range of lignocellulosic biomass may be a promising measure to promote the economical production of cellulosic ethanol. Corn fiber, a byproduct from the corn deep-processing, is an attractive feedstock for cellulosic ethanol production because of its rich carbohydrate content (generally exceeding 65% of dry weight), almost no transportation cost, and low lignin content allow it to be easily handled. This study first optimized the hydrolysis conditions, including the pretreatment and enzymolysis process based on dilute sulfuric acid, to achieve a high sugar yield. Then, the corn fiber hydrolysates obtained under different hydrolysis conditions were suitably fermented by different C5/C6 co-fermentation Saccharomyces cerevisiae, indicating that the hydrolysate at high solid loading (20%) needs to detoxification to a certain extent but not low solid loading (10%) to achieve high ethanol yield. Finally, the fermentation of the 20% solid loading hydrolysates with resin detoxification was performed in a 50 L bioreactor, achieving the sugar (glucose and xylose) metabolic rate of 2.24 g L −1 h −1 and ethanol yield of 92% of the theoretical value, which are the highest reported levels to date. This study provided a potential process route for cellulosic ethanol production from corn fiber from the perspective of the suitability between the upstream hydrolysis process and the downstream fermentation strain.

Preparation of granulated powders via freeze drying at different levels of slurry solid loading and comparison of their powder bed quality in roller-compaction-assisted binder jetting

Granulation can improve the flowability of nanopowder and the density of resultant parts printed by binder jetting. Forward-rotating roller compaction has the potential for further improving the density. In this study, for the first time, powder recoating tests of different granulated alumina powders were conducted on a commercially available binder jetting printer equipped with a forward-rotating roller compaction system. Freeze drying was used to prepare the granulated powder. Four different granulated powders were prepared from slurries with different levels of solid loading: 2, 5, 10, and 15 vol%, respectively. Powder bed quality, including defects on powder bed surface and maximum powder bed density without defects, was compared among the granulated powders. When the compaction ratio was too high, granulated powders with low solid loading levels of 2 and 5 vol% showed much fewer compaction-induced defects (including surface ridges and edge ridges) on powder bed surface than those with high solid loading levels of 10 and 15 vol%. As the solid loading level increased from 2 to 15 vol%, the maximum powder bed density without defects decreased from 19.5% to 16.0%. This study showed that a granulated powder prepared from a low level of slurry solid loading could reduce the compaction-induced defects on powder bed surface and enhance the powder bed density in roller-compaction-assisted binder jetting.

Hydrodynamic study of the operating window of a stator-rotor vortex chamber reactor

The gas-solid vortex reactor is promising for process intensification while the huge gas consumption and relatively low solids loading can be a hurdle for some industrial applications. Therefore, an improved design, the stator-rotor vortex chamber (STARVOC) has been proposed. To construct the operating window, five materials with sizes of 300–1000 μm and densities of 700–2330 kg/m3 are tested at varying rotational speeds from 300 to 600 RPM and superficial gas flow rates from 0 to 2.3 m/s. A quantitative assessment of the bed's axial uniformity is conducted and a minimum rotational speed is determined. A semi-empirical correlation is developed for the terminal velocity of particles, enabling obtaining maximum solids loading and identifying maximum rotational speed. It is found that the operating window can be divided into six zones and the appropriate zone for uniform fluidization is identified. This framework provides operational guidelines for STARVOC implementation in drying and reactive applications.

Improving lactic acid yield of hemicellulose from garden garbage through pretreatment of a high solid loading coupled with semi-hydrolysis using low enzyme loading

Byproduct (acetate and ethanol) generation and carbon catabolite repression are two critical impediments to lactic acid production from the hemicellulose of lignocellulosic biomass. To reduce byproduct generations, acid pretreatment with high solid loading (solid–liquid ratio 1:7) of garden garbage was conducted. The byproduct yield was only 0.30 g/g during in the subsequent lactic acid fermentation from acid pretreatment liquid and 40.8% lower than that of low solid loading (0.48 g/g). Furthermore, semi-hydrolysis with low enzyme loading (10 FPU/g garden garbage cellulase) was conducted to regulate and reduce glucose concentration in the hydrolysate, thereby relieving carbon catabolite repression. During the lactic acid fermentation process, the xylose conversion rate was restored from 48.2% (glucose-oriented hydrolysis) to 85.7%, eventually achieving a 0.49 g/g lactic acid yield of hemicellulose. Additionally, RNA-seq revealed that semi-hydrolysis with low enzyme loading down-regulated the expression of ptsH and ccpA, thereby relieving carbon catabolite repression.

Pore structure regulation of hierarchically porous TiO2 ceramics derived from printable foams

Titanium dioxide (TiO2) is widely used as pollutants degradation material because of the effective photocatalytic capacity, while broad applications are limited due to their traditional forms for application involving as-received powders or coating on carrier. Herein, a novel method for hierarchically porous TiO2 ceramics with designable pores has been put forward, that is direct ink writing of printable particle-stabilized foams. The uneven particle distribution or low solid loading caused weak areas of particle self-assembly on pore wall during foaming, leading to fracture to form interconnected pore structure once grain growth happened during following sintering process. Both open and closed pore structure could be well controlled by adjusting powder composition, sintering temperature and solid loading. The prepared porous TiO2 ceramics possess homogeneous pores, high porosity of 81.76%, bulk density of 0.78 g/cm3 and compressive strength of 11.8 MPa, which can be readily exploited in filter component, catalyst supports, biological scaffolds, especially those with sophisticated shape.

酸化スズナノ粒子サスペンションを用いたマイクロスケールのパターニング

This review focuses on our results on the fabrication of large-area patterning of tin oxide suspensions by the “micromolding in capillary” (MIMIC) method, one of the soft lithography techniques. Usually, suspensions with high solid loadings have been experimented, but since the filling mechanism of the MIMIC method is capillary action, the viscosity increases during the process, resulting in a smaller patterning area. We have confirmed that a low solids ethanol suspension of tin oxide nanoparticle can be used to achieve large-area patterning, forming a stripe pattern with a thickness of almost 1/3 the depth of the mold channel, resulting in a dense structure. Confirming the patterning mechanism, we found that controlling solvent evaporation during the process was very effective. It is expected that this MIMIC process for low solids loading suspensions of nanoparticles will be widely deployed for other types of ceramic suspensions.

Microstructural evolution and tribological behavior of suspension plasma sprayed CuO as high-temperature lubricious coatings

Suspension plasma spraying (SPS) was used to produce three different CuO coatings by varying spray distance and solid loading within the suspension. The low spray distance (30 mm) and high solid loading (20 wt%) in the suspension resulted in the deposition of dense coatings as compared to other spray conditions (i.e., a distance of 40 mm and solid loading of 10 wt%). The tribological performance of the dense coating was investigated at 25 °C and 300 °C under dry sliding conditions. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman analysis were used to characterize the coating, and corresponding wear tracks to determine the wear mechanisms. The results showed that the friction coefficient of the CuO coating decreased from 0.7 at 25 °C to 0.46 at 300 °C. Similarly, the wear rate at 300 °C decreased by 50% compared to the wear rate at 25 °C. Ex-situ analysis showed an increased oxygen content on the worn surfaces at 300 °C and the formation of a smooth uniform tribofilm. At 25 °C, a thicker transfer film was observed on the counterface, which leads to a different velocity accommodation mode and, thus, relatively high friction.

Strength of additively manufactured alumina with different debinding and sintering heat treatments

AbstractLithography‐based ceramic manufacturing (LCM) utilizes slurries with low solids loading, which makes pressureless sintering to full density especially difficult. A further compounding issue in sintering to full density and establishing structure–property–processing relationships for LCM alumina is the fact that the current literature lacks consensus on heat treatments to achieve full densities. Treatment specifics that are recorded are frequently ambiguous and insufficiently detailed. In this work, temperatures and times for debinding and sintering schedules were varied to characterize the influence of heat treatment parameters on density, microstructure, and flexural strength of high‐purity, LCM‐formed alumina. Removing the bisque‐fire from debinding and fine‐tuning sintering parameters produced parts with full densities, high flexural strengths, and Weibull moduli that match or exceed the values documented in a round robin study of traditionally processed alumina.

Negative additive manufacturing of Al2O3-Al cermet material by fused deposition and Direct Ink Writing

Although additive manufacturing is an attractive alternative for the manufacturing of complex ceramic geometries, the manufactured parts have low mechanical properties due to low solid loading, high porosity, and geometrical distortions. Introducing ductile metal particles into the brittle ceramic matrix is an effective technique to enhance the geometrical accuracy and mechanical properties of the printed part. In the current research, the Direct Ink Writing technique is used to fabricate alumina-based matrix composite reinforced with Al particles by negative additive manufacturing. A homogenous cermet mixture in the form of Al 2 O 3 -Al with various Al compositions (5 vol.%, 10 vol.%, 15 vol.%, and 20. vol.%) was achieved by high-energy ball milling. A slurry was prepared by mixing the milled powder with the carboxymethyl cellulose binder and sodium silicate in the deionized water. Rheological measurements of all the slurries were carried out to investigate the shear-thinning behavior of the pastes. The slurry was cast into the polylactic acid mold as the mold was built up layer by layer simultaneously using a Mitsubishi robotic manipulator. The printed parts were dried, demolded by dissolving in Dichloromethane (DCM) solution, and sintered at 1400°C for 6 hours. X-ray diffraction results revealed two distinguished phases (ceramic and metal) in the finished part. It is possible to formulate printable alumina-aluminum cermet slurries with solid content as high as 50 vol.% and 97% density. It was found that by the inclusion of metallic Al phase, the micro-hardness reduces as compared to monolithic alumina ceramic.

The role of binding modules in enzymatic poly(ethylene terephthalate) hydrolysis at high-solids loadings

In nature, enzymes that deconstruct biological polymers, such as cellulose and chitin, often exhibit multi-domain architectures, comprising a catalytic domain and a non-catalytic binding module; the latter serves to increase the enzyme concentration at the substrate surface. This multi-domain architecture has been shown to improve the hydrolysis of poly(ethylene terephthalate) (PET) using engineered cutinase enzymes. Here, we examine the role of accessory binding modules at industrially relevant PET solids loadings necessary for cost-effective enzymatic recycling. Using a thermostable variant of leaf compost cutinase (LCC), we produced synthetic fusion constructs of LCC with five type A carbohydrate-binding modules (CBMs). At solids loadings below 10 wt %, the CBMs improve aromatic monomer yield from PET, but above this threshold, conversion extents up to 97% are reached with no added benefits from the presence of CBM fusions. This suggests that fusion constructs with the herein studied CBMs are not necessary for industrial enzymatic PET recycling. • A new variant of LCC exhibits higher thermostability and greater PET turnover • Specific CBMs stimulate PET hydrolysis at low-solids loading • The advantage of these CBMs is lost at industrially relevant high-solids loading Closed-loop recycling and open-loop upcycling of waste plastics represent a suite of critical technologies to address the plastic-waste pollution crisis. Enzymatic deconstruction of the synthetic polyester poly(ethylene terephthalate) (PET) is among the several options available for chemical recycling of this common plastic. While early demonstrations of enzymatic PET recycling have shown feasibility, the technology is not yet cost competitive with production of virgin petroleum-derived PET. This study analyzes an enzyme engineering approach that takes a lesson from nature to improve the catalytic efficiency of PET-hydrolyzing enzymes and evaluates the impact of this strategy under reaction conditions that simulate a key industrial feature of enzymatic PET recycling. The implications of this study can help focus the resources available to the field on solutions that can enable rapid deployment of viable technologies to realistically address plastics pollution. Enzymatic recycling of PET offers a promising solution to the global plastic problem. Research into accessory domains to enhance PET turnover has so far not been tested at high PET solids loadings. Here, we show that carbohydrate-binding domains do not offer any benefit at high PET solids loadings that are relevant to industrial-scale biorecycling.

Understanding the effects of low enzyme dosage and high solid loading on the enzyme inhibition and strategies to improve hydrolysis yields of pilot scale pretreated rice straw

The commercial viability of 2G bioethanol production is dependent on cost-effective and efficient enzymatic hydrolysis of biomass at low enzyme and high dry solid loadings. In the present study, rice straw was subjected to a dilute acid pretreatment in a continuous pilot plant (250 kg/day).It was observed that, the glucan conversion yields were reduced by 26% at high solid loading (20% w/w) with low enzyme dosage of 3 FPU/g w/w of in-house developed enzyme (MRJ16). Thus, multiple approaches were investigated to enhance the glucan conversion yields, a) fed batch approach (splitting biomass or enzyme dosage during process), b) additives supplementation (surfactants, metal ions, non-enzymatic proteins and activated charcoal) and c) enzyme blending with accessory enzymes. Results showed that, the 3-stage fed-batch approach enhanced the hydrolysis yield by 12% in comparison to 14.3% increase with the selected surfactant (0.5% w/w Ecosurf). The selected metal salt (NiCl2, 1 mM) increased the glucan conversion by 13.2%, while, the non-enzymatic proteins (5% w/w yeast hydrolysate and yeast extract) improved the yields to 14.8% and 14.4%, respectively. The activated charcoal at a concentration of 0.5% w/w enhanced the hydrolysis yields by 14.4%. Further, 15.1% increase in sugar yield was obtained by supplementing the in-house produced enzyme (MRJ16) with xylanase from Thermomyces lanuginosus and BGL from Penicillium janthinellum EMS-UV-8. Finally, a unique optimized strategy was developed on the basis of selected approaches and parameters which demonstrated 24.7% higher saccharification in comparison to control. To the best of our knowledge, this is the only study available in literature where; a wide range of strategies were studies on a single feedstock (i.e. rice straw) pretreated at pilot-scale and determine its effect for improved enzymatic hydrolysis. Furthermore, developed process helps us to save (almost 2X) expensive enzyme to achieve same level of glucan conversion (∼62.0%) to make the overall process cost effective by using cheap and easily available additives. The current study also provided an in-depth understanding of enzyme inhibition at low enzyme dosages and high solid loadings in an industrially relevant scenario.

Enhancing the Regression Rate of Hydroxyl-Terminated-Polybutadiene-Based Mixed Hybrid Rockets

This study has identified potential hydroxyl-terminated-polybutadiene (HTPB) based fuel compositions that provide a high-density specific impulse but do not burn like a solid propellant. Due to low solid loading in these fuel compositions, precuring the HTPB and isophorone diisocyanate mixture is necessary to get uniform density and composition across the length of the grain. Nearly 7 h of precuring gave the best results in terms of uniformity of the propellant composition. This study also discusses the effect of available burn rate modifiers for ammonium perchlorate and a type of aluminium on the enhancement of regression rate in mixed hybrid rockets. Finally, the hybrid propellants developed had an oxidizer mass flux index close to 0.5, which is desirable.

Additive‐Free, Gelled Nanoinks as a 3D Printing Toolbox for Hierarchically Structured Bulk Aerogels

AbstractAerogels are highly porous solids that maintain the properties of individual nanomaterials at a macroscopic scale. However, the inability to fabricate hierarchical architectures limits technological implementation in energy storage, gas‐sorption, or catalysis. A 3D‐printing methodology for additive‐free TiO2 nanoparticle‐based aerogels is presented with full control of the nano‐, micro‐, and macroscopic length‐scales. To compensate for ink's low solid loading of 4.0 vol% and to enable subsequent processing into aerogels via supercritical drying, the printing is done in a liquid bath of alkaline pH. The 3D‐printing protocol retains a high specific surface area of 539 m2 g–1 and a mesopore diameter of 20 nm of conventionally casted aerogels while offering an unparalleled designability on the micrometer scale. To illustrate the new geometric freedom of 3D‐printed aerogels, the microstructure of a strongly light‐absorbing, photothermal Au‐nanorod/TiO2 aerogel is defined. To date, photothermal nanomaterials are mainly applied in the form of unstructured films where scalability is limited by light attenuation. Microstructures in 3D enhance light penetration by a factor of four and facilitate spatially defined heating on a macroscopic scale. The process can be generalized for a broad material library and allows to design inks with specific functionality, thus making aerogels adaptable for their target application.

Declining carbohydrate solubilization with increasing solids loading during fermentation of cellulosic feedstocks by Clostridium thermocellum: documentation\xa0and diagnostic tests

BackgroundFor economically viable 2nd generation biofuels, processing of high solid lignocellulosic substrate concentrations is a necessity. The cellulolytic thermophilic anaerobe Clostridium thermocellum is one of the most effective biocatalysts for solubilization of carbohydrate harbored in lignocellulose. This study aims to document the solubilization performance of Clostridium thermocellum at increasing solids concentrations for two lignocellulosic feedstocks, corn stover and switchgrass, and explore potential effectors of solubilization performance.ResultsMonocultures of Clostridium thermocellum demonstrated high levels of carbohydrate solubilization for both unpretreated corn stover and switchgrass. However, fractional carbohydrate solubilization decreases with increasing solid loadings. Fermentation of model insoluble substrate (cellulose) in the presence of high solids lignocellulosic spent broth is temporarily affected but not model soluble substrate (cellobiose) fermentations. Mid-fermentation addition of cells (C. thermocellum) or model substrates did not significantly enhance overall corn stover solubilization loaded at 80 g/L, however cultures utilized the model substrates in the presence of high concentrations of corn stover. An increase in corn stover solubilization was observed when water was added, effectively diluting the solids concentration mid-fermentation. Introduction of a hemicellulose-utilizing coculture partner, Thermoanaerobacterium thermosaccharolyticum, increased the fractional carbohydrate solubilization at both high and low solid loadings. Residual solubilized carbohydrates diminished significantly in the presence of T. thermosaccharolyticum compared to monocultures of C. thermocellum, yet a small fraction of solubilized oligosaccharides of both C5 and C6 sugars remained unutilized.ConclusionDiminishing fractional carbohydrate solubilization with increasing substrate loading was observed for C. thermocellum-mediated solubilization and fermentation of unpretreated lignocellulose feedstocks. Results of experiments involving spent broth addition do not support a major role for inhibitors present in the liquid phase. Mid-fermentation addition experiments confirm that C. thermocellum and its enzymes remain capable of converting model substrates during the middle of high solids lignocellulose fermentation. An increase in fractional carbohydrate solubilization was made possible by (1) mid-fermentation solid loading dilutions and (2) coculturing C. thermocellum with T. thermosaccharolyticum, which ferments solubilized hemicellulose. Incomplete utilization of solubilized carbohydrates suggests that a small fraction of the carbohydrates is unaffected by the extracellular carbohydrate-active enzymes present in the culture.

Green mechano-chemical processing of lignocellulosic biomass for lignin recovery

Lignin extraction from biomass is heavily dependent on chemical processes that are harmful to the environment and the quality of the recovered lignin. Ionic liquid solvents are some of the latest solutions in green processing; however, their implementation for lignin recovery is limited by their high cost, typically high loadings requirements, and long processing times. To overcome these issues, in this study, high loadings of mixed hardwood flour (MHF) were processed with 1-butyl-3-methylimidazolium chloride (BmimCl) in a batch mixer. The rheological behaviour of the biomass and ionic liquid mixture was studied. The mixture had a high complex viscosity (approx. 107 Pa s) at low shear rates and displayed pronounced shear thinning behavior at 50 wt% MHF loading. A 22 factorial design was also implemented to study the effects of MHF solid loading amount and residence time on lignin extraction yield. A maximum yield of 36.6% was obtained at the maximum solid loading amount and residence time (50 wt% and 45 min, respectively). The extracted lignin samples were also characterized in comparison with commercial Kraft lignin and lignosulfonate. The novelty of this study is the successful lignin extraction at high solid loadings and shorter residence times compared to previous biomass pre-treatments with ionic liquids that employs low solid loading and long processing times.

Understanding the Effects of Low Enzyme Dosage and High Solid Loading on the Enzyme Inhibition and Strategies to Improve Hydrolysis Yields of Pilot Scale Pretreated Rice Straw

Understanding the Effects of Low Enzyme Dosage and High Solid Loading on the Enzyme Inhibition and Strategies to Improve Hydrolysis Yields of Pilot Scale Pretreated Rice Straw