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Torrefaction is a pretreatment method that converts biomass to a fuel-like substance that can replace coal for sustainable power generation. In this work, a thermodynamic-based process simulation model was developed to simulate the gasification of empty fruit bunch (EFB), with torrefaction as pretreatment, to determine the optimum conditions; equivalence ratio, reactor temperature, torrefaction medium concentration, steam-to-biomass (S/B) ratio and system configuration were studied to determine their influence on hydrogen concentration, higher heating value (HHV), syngas ratio and cold gas efficiency (CGE). The highest hydrogen yield was obtained at an S/B ratio of 1.3 at 800 °C, with a syngas ratio of 2.5 and a CGE of 84%. Concentration of torrefaction medium showed no effect on hydrogen concentration due to the simplicity of the model used, but work is in progress in this direction. Therefore, steam gasification is more suitable than air gasification in hydrogen production. • A process model for biomass torrefaction and gasification was developed. • Introduction of steam into gasifier increased H 2 concentration by 10.1%. • The H 2 /CO ratio was higher with lower gasifier temperature, lower equivalence ratio and higher steam/biomass ratio. • Optimum conditions for hydrogen production have been identified. [ABSTRACT FROM AUTHOR]

To reveal the effect of torrefaction pretreatment on pyrolysis and gasification reactivity of biomass, corn cob was first subjected to torrefaction pretreatment in a fixed-bed reactor at various reaction temperatures. The pyrolysis reactivity, kinetics, and gasification reactivity of torrefied corn cob were systematically assessed by various methods, proving that torrefaction pretreatment has a substantial influence on the physicochemical properties of corn cobs. The O/C and H/C molar ratios of corn cobs considerably drop with the increasing torrefaction temperature, and their higher heat-ing value (HHV) and energy density rise as well. It is found that torrefaction improves the pyrolysis reactivity of corn cobs because hemicellulose degradation is more severe than cellulose degradation during torrefaction, resulting in an increase in the percentage of cellulose in torrefied corn cobs. However, the severe depolymerization, polycondensation, and carbonization reaction during torre-faction of corn cobs at 280–300 °C can lead to a significant decline in the pyrolysis reactivity of corn cobs. Torrefaction pretreatment increases the pyrolysis activation energy of corn cobs, in addition to decreasing the char gasification reactivity of corn cob. The average char gasification reactivity of corn cobs drops when torrefaction severity increases. The passivation of active sites on the char surface may cause condensation and carbonation reactions of corn cobs during torrefaction. These findings provide new sights into the reasonable design of efficient torrefaction methods for appli-cation prior to pyrolysis and gasification of biomass. [ABSTRACT FROM AUTHOR]

Motivated by green building applications (bio-composite and insulation materials), thermogravimetric and kinetic analysis is applied to investigate the thermal degradation of cleaned hemp fibers (F), obtained after water retting and mechanical decortication of dioecious plant stalks, and technical fiber (TF), obtained after field retting of monoecious plant stalks. Celluloses (microcrystalline PH105 cellulose and cotton linter cellulose) are used for comparison. F and TF dynamic curves are well described by a four-step scheme. The dominant one concerns pseudo-cellulose decomposition with the release of 70 and 54 mass% volatile matter, respectively. The corresponding activation energies are in the range of typical cellulose values (223 and 211 KJ mol−1). Fiber pretreatments (water washing, mild torrefaction, mercerization) modify the pseudo-cellulose content (release of 73–80 mass% volatile matter) and properties, as testified by the higher activation energies (229–248 kJ mol−1) of the decomposition process. The decortication method also contributes remarkably to the characteristics of the fiber cellulose. [ABSTRACT FROM AUTHOR]

• A promising approach to co-management of FA and TC was explored. • A new acidic index was proposed to evaluate the effective acidity of TCs. • TC dissolved and dispersed locally aggregated Ca minerals as in-situ catalysts. • Highly-dispersed Ca improved many-fold reactivity and syngas yield of the FATCs. • TCs played an apparent desulfurization role during the blending of FA and TCs. This study explored a promising approach to the co-management of torrefaction condensates (TCs) from biomass and carbon-rich fly ash (FA) derived from an industrial fluidized-bed coal gasifier. TC was a low-quality liquid product consisting mostly of water and a small amount of organic acids and other oxygenated organics. FA was the ultra-fine particulates with high carbon content (40–70%) and some extreme characteristics such as ultra-low volatiles, low reactivity, and high ignition temperature. The blending of FA and TC induced most of the organic components in TC to be chemically or physically adsorbed by FA, accounting for 3–13 wt% of the resultant mixtures of FA and TC (FATCs) and 11–33 wt% of the TCs. The acidic components in TC dissolved locally aggregated Ca minerals in FA, resulting in more evenly dispersed Ca on the surface of FA as an in-situ catalyst. As a result, FATCs exhibited a many-fold improvement in CO 2 gasification reactivity compared to FA. And the syngas evolution rate of FATC gasification in steam-oxygen atmosphere was also remarkably elevated. In addition to the promoting effect on gasification, the combustion performance of FATCs was also greatly improved. Specifically, the ignition and burnout temperatures of FATCs were 46.5–68.5 °C and 12.4–31.7 °C lower than those of raw FA, respectively. The lower activation energy also demonstrated the higher reactivity of FATC gasification and combustion. [ABSTRACT FROM AUTHOR]

This review deals with the simulation and optimization of the dry- and wet-torrefaction processes of lignocellulosic biomass. The torrefaction pretreatment regards the production of enhanced biofuels and other materials. Dry torrefaction is a mild pyrolytic treatment method under an oxidative or non-oxidative atmosphere and can improve lignocellulosic biomass solid residue heating properties by reducing its oxygen content. Wet torrefaction usually uses pure water in an autoclave and is also known as hydrothermal carbonization, hydrothermal torrefaction, hot water extraction, autohydrolysis, hydrothermolysis, hot compressed water treatment, water hydrolysis, aqueous fractionation, aqueous liquefaction or solvolysis/aquasolv, or pressure cooking. In the case of treatment with acid aquatic solutions, wet torrefaction is called acid-catalyzed wet torrefaction. Wet torrefaction produces fermentable monosaccharides and oligosaccharides as well as solid residue with enhanced higher heating value. The simulation and optimization of dry- and wet-torrefaction processes are usually achieved using kinetic/thermodynamic/thermochemical models, severity factors, response surface methodology models, artificial neural networks, multilayer perceptron neural networks, multivariate adaptive regression splines, mixed integer linear programming, Taguchi experimental design, particle swarm optimization, a model-free isoconversional approach, dynamic simulation modeling, and commercial simulation software. Simulation of the torrefaction process facilitates the optimization of the pretreatment conditions. [ABSTRACT FROM AUTHOR]

Torrefaction is known to reduce the logistical costs of biomass. Torrefied biomass' prospects as feedstock for fermentation to liquid biofuel are largely unknown. This study investigated the interactions of torrefaction and alkaline pretreatment of wheat straw on glucose yields from enzymatic hydrolysis, including treatment order and the potential for pH to play a role in the process. Across a range of torrefaction severities with temperatures of 200 °C, 220 °C, and 240 °C and durations of 20, 40, and 60 min, torrefaction had a negative impact on glucose yield of wheat straw with or without alkaline pretreatment and regardless of the order of alkaline pretreatment. Alkaline pretreatment after torrefaction results in higher glucose yield than alkaline pretreatment before torrefaction, or by torrefaction alone. Hence, there is the prospect for adding logistical benefits of torrefaction to the bioethanol system if alkaline pretreatment is coupled with torrefaction. Decreasing trend in pH with increase in torrefaction severities was observed for trials without buffer, indicating chemical changes causing the decrease in pH might be associated with the reduction in yield. [ABSTRACT FROM AUTHOR]

Accumulation of chicken manure with litter (sawdust or fragmented straw) that is produced in large quantities at poultry farms (in producing 1 kg of poultry, 1–3 kg of manure with litter is obtained) poses a serious problem for the environment. Poultry farms are among the largest consumers of electricity, which can be generated by combusting manure with litter, also jointly with coal, in bubbling or circulating fluidized bed furnaces. For making the combustion more efficient and environmentally friendly (reducing carbon oxide emissions) the manure wetness and the content of volatiles in it should be decreased, and its heating value should be increased. To this end, manure with litter can be subjected, prior to its combustion, to pretreatment using the hydrothermal carbonization or torrefaction method. The article presents a comparison of the results obtained from studies of methods for processing a mixture of chicken manure and sawdust into biofuel in superheated steam. Chicken manure and its mixture with sawdust in the ratios 1 : 1, 1 : 2, and 2 : 1 were subjected to thermochemical treatment. Hydrothermal carbonization was carried out in a batch laboratory autoclave at a temperature of 220°С for 1 and 4 h. Biomass torrefaction was carried out in a fluidized bed reactor with the bed formed by biochar particles that were preliminarily obtained in superheated steam at temperatures of 300 and 350°С. It has been found that by applying the hydrothermal carbonization method, the carbon content in manure with litter can be increased from 42 to 63%, and the higher heating value from 16.7 to 17.8 MJ/kg. In turn, by applying the method of fluidized bed torrefaction in superheated steam, these indicators can be increased to 75% and 18.8 MJ/kg, respectively. The hydrothermal carbonization and torrefaction processes require significant energy expenditures. For making both processes more economically efficient, the possibility of extracting, from the spent water (or condensate), 5-hydroxymethylfurfural, which is regarded as a key reagent, a so-called platform chemical, for producing various practically important substances, including polymers, pharmaceutical drugs, solvents, and fuels, is being researched. It has been determined that the content of 5-hydroxymethylfurfural in these aqueous media makes 0.02–0.80 g/dm3 and depends on the biomass thermochemical treatment method and temperature at which the process was performed. [ABSTRACT FROM AUTHOR]

In this study, three locally available biomasses, namely miscanthus, hops, sewage sludge, and additionally, their mixtures, were subjected to the torrefaction process to improve their fuel properties. The torrefaction process was conducted at 250–350 °C and 10–60 min in a nitrogen (N2) environment. The torrefaction temperature and time were studied to evaluate the selected biomass materials; furthermore, heating values, mass and energy yields, enhancement factors, torrefaction severity indexes (TSI), and energy-mass co-benefit indexes (EMCI) were calculated. In addition, thermogravimetric (TGA) and Fourier transform infrared analyses (FTIR) were performed to characterize raw and torrefied biomass under the most stringent conditions (350 °C and 60 min). The results showed that with increasing torrefaction temperature and duration, mass and energy yields decreased, and heating values (HHVs) increased for all studied biomasses. The results of the TSI and EMCI indexes showed that the optimum torrefaction conditions were as follows: 260 °C and 10 min for pure miscanthus and hops, whilst this could not be confirmed for the sewage sludge. Furthermore, the combination of sewage sludge and the above-mentioned types of lignocellulosic biomass exhibited better fuel properties than sewage sludge alone. [ABSTRACT FROM AUTHOR]

The carbon dioxide (CO2) torrefaction of oil palm empty fruit bunch (OPEFB) pellets was investigated at various temperatures from 250 to 300 °C and residence times from 15 to 60 minutes. The objective was to investigate the effects of CO2 torrefaction on the yield and characteristics of the torrefied products. The optimal conditions for maximum mass yield (MY) of CO2 torrefaction were also examined by response surface methodology (RSM) using full factorial design. Results revealed that temperature and time significantly influenced the mass (MY), liquid (LY) and gas (GY) yields. The MY and energy yield (EY) decreased with increasing severity of torrefaction, whereas the LY, GY, energy density (DE) and higher heating value (HHV) increased during the process. Characterisation revealed substantial improvements in the microstructure, pH, hydrophobicity and grindability of the torrefied pellets compared with the raw pellets. The thermal ignition and degradation characteristics of the OPEFB pellets were also significantly transformed after torrefaction. The liquid torrefaction products contained an acidic, turbid and pungent mixture of water and organic compounds. RSM optimisation revealed the optimal conditions: temperature of 275 °C and residence time of 35 minutes with the predicted MY of 50.54%, mass loss of ML = 49.46% and HHV = 24.47 MJ/kg. The findings revealed that CO2 torrefaction is a practical approach to clean energy recovery. [ABSTRACT FROM AUTHOR]

Torrefaction is a thermal treatment method used to achieve solid-phase biofuel. Raw biomass generally have low heating value and high moisture content; thus, these characteristics should be enhanced before using it as a fuel. In this study, herbaceous biomass kenaf was torrefied at 220, 260, 300, and 340 °C under nitrogen atmosphere for 30 min to investigate the effect of temperature on its properties. The properties of torrefied kenaf were classified into two groups: physical properties such as mass and energy yields, moisture content, and proximate analysis and chemical properties such as functional groups and chemical compositions of sugars and lignin. The mass and energy yield of torrefied kenaf decreased as the reaction temperature increased. In addition, an increase in carbon content and a rapid decrease in oxygen content were observed in torrefied kenaf, which indicated the degradation of compounds such as hemicellulose and cellulose. Elemental analysis, proximate analysis, thermal analysis, Fourier transform infrared spectroscopy, and chemical composition analysis were performed to further investigate the characteristics of torrefied kenaf. [ABSTRACT FROM AUTHOR]

This review aims to show the significance of the use of secondary carbon bio-carriers for iron and steel production. The term 'secondary carbon bio-carriers' in this review paper refers to biomass, torrefied biomass, biochar, charcoal, or biocoke. The main focus is on torrefied biomass, which can act as a carbon source for partial or complete replacement of fossil fuel in various metallurgical processes. The material requirements for the use of secondary carbon bio-carriers in different metallurgical processes are systematized, and pathways for the use of secondary carbon bio-carriers in four main routes of steel production are described; namely, blast furnace/basic oxygen furnace (BF/BOF), melting of scrap in electric arc furnace (scrap/EAF), direct reduced iron/electric arc furnace (DRI/EAF), and smelting reduction/basic oxygen furnace (SR/BOF). In addition, there is also a focus on the use of secondary carbon bio-carriers in a submerged arc furnace (SAF) for ferroalloy production. The issue of using secondary carbon bio-carriers is specific and individual, depending on the chosen process. However, the most promising ways to use secondary carbon bio-carriers are determined in scrap/EAF, DRI/EAF, SR/BOF, and SAF. Finally, the main priority of future research is the establishment of optimal parameters, material quantities, and qualities for using secondary carbon bio-carriers in metallurgical processes. [ABSTRACT FROM AUTHOR]

This study focuses on the physical and combustion indices of briquettes produced from thermally treated cornhusk (CH) and sawdust (SD) through torrefaction. The raw and torrefied feedstocks were combined at different blending ratios and then preconditioned with 10% moisture content. The highest value of density, shatter index, and compressive strength was obtained at 90/10 (CH/SD) ratio. The calorific value and fixed carbon of the torrefied briquettes increased between 37.56–42.42% and 42.90–49.75% over the raw briquettes while the volatile matter decreased by 26.88–38.57%. Moreover, the combustion indices show the briquettes from these feedstock blends are suitable to replace coal. Briquettes from torrefied cornhusk and sawdust could serve as an alternative fuel for domestic and industrial heating applications in Nigeria.

The heating performance of empty fruit bunch pellets (EFBPs) has been limited by its low energy density, high moisture, and ash content. Hence, microwave co-torrefaction (MCT) was performed with microwave heating unto waste oil mixed EFBP to produce high-energy biofuel. However, the non-homogeneous electromagnetic fields distribution in the microwave cavity results in an uneven heating behavior, producing the hot and cold spots. Hence, MCT coupled with helical lift was examined for its potential to improve heat distribution. The effect of temperature and types of waste oil on the proximate analysis and surface properties were studied. In comparison to the conventional torrefaction using a furnace (>30 min), MCT provided rapid heating (50–80°C·min−1) and a shorter process time (10 min). The use of helical lift with 2-dimensional movement – rotational (24 rpm·min−1) and vertical motion (5 cm·min−1) simultaneously, distributed microwave radiation uniformly for rapid heating. The proximate analysis demonstrated that the ash content was reduced from 8 to 3 wt%, and the highest fuel ratio of 2.0 was achieved. Additionally, the highly porous structure of EFBP biochar can act as an activated carbon precursor. MCT coupled with helical lift represents a promising approach to prevent hot spots during microwave heating.

In this study, wood sawdust as waste residue from wood processing mills was pretreated using torrefaction to improve fuel properties and densified to facilitate transportation. Sawdust was torrefied in a fixed bed reactor using inside temperatures (IT) of 230, 260 and 290 °C for 15, 30 and 45 min, residence time. Due to the low calorific value of the treatments, the outside temperature (OT) of the fixed bed reactor was used instead for a fixed duration of 45 min, which resulted in an increase in energy value by 40% for the most severe conditions. The mechanical strength of the pellets was enhanced by adding 20% binder (steam-treated spruce sawdust) to biochar, which improved the pellet tensile strength by 50%. Liquid by-products from the torrefaction process contained furfural and acetic acid, which can be separated for commercial uses. Thermochemical analysis showed better fuel properties of OT torrefied samples such as high fixed carbon (52%), low volatiles (41%) and lower oxygen contents (27%) compared to IT torrefied samples (18, 77 and 43%, respectively). Low moisture uptake of torrefied pellets compared to raw pellets, along with other attributes such as renewability, make them competent substitutes to fossil-based energy carriers such as coal.

• Torrefaction enhances biomass properties, aiding fluidized bed reactor performance. • Biomass proportions in bed mixtures don't affect minimum fluidization velocity. • Hazelnut shells and olive pits torrefied at 280 °C show improved fluidization. Torrefaction has emerged as a promising technology for optimizing the efficiency of thermochemical processes. However, many challenges still need to be addressed regarding its integration with other processes, such as gasification. This work investigates the potential of torrefaction to transform the properties of biomass mixtures, improving operations in fluidized bed reactors. Experimentally, hazelnut shells and olive pit mixtures were torrefied at 280 °C for 45 min to analyze how torrefaction affected the minimum fluidization velocity as a bulk density function. The results were compared to other biomasses from the literature. Our findings show that torrefaction can stabilize minimum fluidization velocity at 0,45 m/s for mixtures of biomasses with bulk densities below 700 kg/m3 and particle size range (T) of 1,7 < T < 2,36 × 10−3 m. These findings collectively emphasize the potential of torrefaction as an effective technology for utilizing agro-industrial residues in energy generation processes not only for the improvement of conversion efficiency but also for operation stability. [ABSTRACT FROM AUTHOR]

Crustacean waste has great potential as fossil fuel substitution and efficient desulfurization to reduce pollutant emissions, but high moisture and poor quality restrict broad-scale utilization. This study used microwave radiation on crayfish shell to investigate the combustion characteristics and desulfurization effect in different atmospheres/pulse microwave cycle. Meanwhile, the structure evolution mechanism and molecular reaction pathways were revealed. The results show that crayfish shell derived fuel has a pleasurable combustion performance and sulfur fixation ability after microwave radiation in flue gas. The heat release of derived fuel increased by 29.9 % after five microwave cycle in flue gas, and activation energy decreased by 3.7 %. By contrast, the heat release increased by 17.4 % after five microwave cycle in inert gas, and activation energy increased by 39.3 %. Subsequently, the effect of microwave cycle times in flue gas on crayfish shell combustion and desulfurization performance was studied. The results show that the heat release of derived fuel gradually increases with microwave cycle. After seven microwave cycle, the derived fuel heat release and SO 2 removal efficiency increased by 34.9 % and 44.4 %, respectively. The results establish the foundation for expanding the utilization pathway of crustacean waste and realizing the low-carbon energy transition. [Display omitted] • Prepared crayfish shell derived fuel use microwave radiation in flue and inert gas. • The effect mechanism of pore structure on combustion performance was elucidated. • Proposed the two reaction pathways of functional groups under microwave radiation. • Microwave radiation in flue gas increased exotherm by 35 % and reduced SO 2 by 44 %. • Crayfish shell derived fuel sync realized the fuel substitution and SO 2 reduction. [ABSTRACT FROM AUTHOR]

[Display omitted] • Using additives can increase economic viability, making biochar production more competitive. • Additives can increase biomass reactivity, conversion rate, and higher biochar yields. • Additives can act as catalysts, facilitating the torrefaction process at lower temperatures, leading to energy savings during torrefaction. • Additives can contribute to increasing carbon retention and enhancing biochar stabilization. • Additives can be used to modify the physical and chemical properties of biochar and tailor it for specific applications. Over the past few years, considerable attention has been devoted to enhancing the torrefaction process, exploring diverse additives to improve either the process itself or the characteristics of torrefaction products. This review examines the recent advancements in torrefaction processes conducted by different research groups for these purposes. A critical evaluation involving the usage of liquid- and solid-based additives in the torrefaction process can have diverse effects depending on the specific condition implied during the torrefaction process (e.g., biomass feedstock, process conditions, and desired outcomes). Therefore, various testing and evaluation procedures should be performed to determine the optimal type and quantity of additives for a specific torrefaction application. The influence of various additives on the torrefied products of different torrefaction processes is summarized in this review. In particular, the additives are systematically categorized, and the effects of the additives on the properties of the respective torrefaction products are also discussed. [ABSTRACT FROM AUTHOR]

This work is focused on the determination of differences in the composition of the surface and bulk of thermally treated Miscanthus rhizomes. The biomass samples were processed in a wide temperature range from 200 to 700°C. The surface of formed biochars was studied with the use of time-of-flight secondary ion mass spectrometry. The obtained results were compared with other analytical methods, such as: thermogravimetry, proximate and ultimate analysis, Fourier transform infrared spectroscopy, etc. The performed studies revealed more intense decomposition of lignocellulose on the surface than in the bulk of treated Miscanthus rhizomes, especially at low temperature range (200–300°C), which was related to the diffusion limitations of intermediates of thermal processing of biomass migrating towards the surface. On the other hand, a decomposition of the surface layers of the studied material finished at lower temperature, while the remaining lignocellulose could still react in the bulk. Generally, the obtained results may be helpful in selecting thermal treatment conditions that allow obtaining optimal surface properties of the created biochar and increasing the scope of its potential applications. • different composition of surface and subsurface layers of formed biochar. • decomposition of the surface layers of the studied biomass ends at about 500°C. • lignocellulose in the bulk still reacts at higher temperature. • thermal treatment facilitates mobility of metals in the biochar structure. • ToF-SIMS allows for comprehensive analysis of thermally treated biomass surface. [ABSTRACT FROM AUTHOR]

Combustible construction solid wastes (CCDW) and paper sludge (PMS) are important components of combustible solid waste (CSW), which are also important ingredient in waste-to-energy system. Torrefaction experiments of CCDW, PMS and their blends in equal proportion (C50S50) were conducted in a tubular furnace reactor at torrefaction temperature (T) of 200–400 °C for 30 min. The fuel properties and migration of heavy metals and Cl of torrefied CCDW, PMS and C50S50 were investigated based on proximate analysis, ultimate analysis, caloric value determination, and the measurement of heavy metals and Cl in solid, liquid and gaseous products. Combustion characteristics of CCDW, PMS, C50S50 and their torrefied solid products were evaluated by TG-FTIR analyzer. The obtained results indicated that torrefaction can improve fuel performance of CCDW, PMS and C50S50. The fixed carbon, higher heating value (HHV) of torrefied solid products increased and volatile matter decreased gradually while T < 250 °C; however, the HHV and energy yield of blended torrefied solid products obviously decreased while T > 250 °C. The combustible index (C n) and burnout index (S) of blended torrefied products at 250 °C were the largest, achieving 111.26 × 10−6 and 0.49 × 10−6. Torrefaction can effectively remove Zn, Hg, As in CCDW, PMS and C50S50. More than 50 % of Cl was released from torrefied C50S50 when T > 300 °C. High torrefaction temperature (T > 300 °C) can remove more heavy metals and Cl, but it has an adverse effect on fuel properties of torrefied products, so the suggested torrefaction temperature is 250 °C. [ABSTRACT FROM AUTHOR]

Tetracycline mycelial residue (TMR), a byproduct derived from the tetracycline fermentation process, is rich in organic matter, making it a promising resource. However, the presence of residual tetracycline and antibiotic resistance genes (ARGs) limits its potential for resource utilization. In this study, torrefaction was employed for the harmless treatment of low-moisture TMR, and the optimized condition was 200.0 °C for 30.0 min. Under this condition, 97.2% of tetracycline (TC) in TMR could be efficiently removed, with more organic matter reserved for resource utilization. The plausible degradation pathway was proposed, involving the formation of lactone structure and anhydro-tetracycline (ATC) during TC degradation, followed by a series of reactions among main functional groups, including concerted reactions, retro-Diels-Alder (RDA), cleavage reactions, and rearrangement. Furthermore, the antibacterial efficacy of degradation products from TC has significantly diminished, and the structure of ARGs and bacteria was disrupted during the torrefaction of TMR. After the treated TMR was amended into the soil as fertilizer, the dissemination of ARGs could also be effectively controlled. Therefore, torrefaction could be recommended as a promising harmless treatment for the resource utilization of low-moisture TMR. [Display omitted] • 97.2% of tetracycline in TMR was removed through torrefaction (200.0 °C, 30.0 min). • The products (200.0 °C, 30.0 min) showed no significant inhibition on the target bacteria. • The antibiotic resistance genes (ARGs) in TMR could be greatly removed. • No significant spread of ARGs was observed in the soil amended with treated TMR. [ABSTRACT FROM AUTHOR]

[Display omitted] • Volatile-char interactions between three components during torrefaction are studied. • Only hemicellulose volatile and cellulose char interaction exists at 250 °C. • Interaction causes significant depolymerisation and amorphization of cellulose. • Cellulose decomposes to dehydrated sugars and aromatic compounds. • A volatile-char interaction mechanism model based three components is developed. Volatile-char interaction is an important phenomenon in biomass thermal conversion process, which significantly contributes to the decomposition, deoxygenation and upgrading of biomass. However, the deep insight into volatile-char interaction mechanisms between hemicellulose, cellulose and lignin is currently unclear. In this work, above mechanism was studied through systematic single-/bi-component torrefactions and the follow-up char analysis. Results demonstrate that only hemicellulose volatile and cellulose char interaction exists during torrefaction at 250 °C, causing over 19.9 wt% of mass loss and 27.3 wt% of O removal for cellulose. This volatile-char interaction causes significant depolymerization and amorphization of cellulose by hydrolysis, acid hydrolysis and esterification reactions. The depolymerized and amorphous cellulose partly thermally decomposes to dehydrated sugars and aromatic compounds through dehydroxylation and aromatization reactions. A volatile-char interaction mechanism model is thus developed. This work provides theoretical insight into biomass thermal conversion and provides basis for the development of new thermochemical method. [ABSTRACT FROM AUTHOR]

Forest residues have been gaining interest as a source of renewable fuels due to their availability and the risks they represent for increasing forest fires. A major drawback for their removal and processing is the cost of transportation, which can be overcome through densification procedures, e.g., torrefaction. To optimize the torrefaction parameters, Cistus ladanifer residues from the Portuguese forest were torrefied for 30 min in a lab-scale reactor at 250 and 350 °C. The quality of the torrefied material was assessed, and its energy and mass yields were determined through thermal analysis. The changes in morphological structure occurring during torrefaction were analysed through scanning electron microscopy. When compared to the original biomass, the charcoal obtained at 350 °C had a substantial increase in energy density accompanied by a significant mass reduction. Increasing the mass in the reactor had a positive effect on the energy yield. For the highest mass tested, a mass reduction of around 30% was obtained and a char with no loss in energy content (with a cumulative heat flow (CHF) of 9.0 MJ/kg compared to 5.8 MJ/kg of the original biomass). Modelling of the reactor allowed the analysis of the heat profile required for torrefaction.

Abundant availability of lignocellulosic biomass (LCB) coupled with diverse pretreatment methods have made it a promising option for energy production. However, it faces several challenges, some of which can be overcome by integrating pretreatment processes. The present study aims to optimize the integration of two different pretreatment methods—torrefaction (to reduce moisture content and fractionate biomass) and alkaline pretreatment of wood waste (to delignify biomass)—and utilize it for bioethanol production. Pretreatment performance was evaluated based on delignification, biomass hydrolysis, and bioethanol production. Initially, torrefaction was performed in a continuous reactor at a temperature range of 225–300 °C, followed by optimization of the critical parameters of alkaline pretreatment of torrefied wood waste (TWW), that is, the temperature, reaction time, solid–liquid ratio, and alkali concentration. Subsequently, the chemical and carbohydrate compositions of raw wood waste (RWW) and TWW were studied, followed by enzymatic hydrolysis and bioethanol fermentation. Integrated pretreatment positively impacted the cellulose and glucose contents of raw and torrefied biomass at lower temperatures. The enzymatic hydrolysis of TWW treated with alkali produced higher levels of glucose and bioethanol than (stand-alone) TWW. These results can be used as a basis for choosing the most suitable pretreatment for enhanced biomass conversion.

This study characterizes and compares the physicochemical parameters of three types of biomass: giant miscanthus, wheat straw, and white willow. An analysis of the chlorine content in the biomass was determined using a 5E-FL2350 fluorine and chlorine analyzer. In addition, energy parameters characterizing the biomass were determined, such as the content of ash and volatile matter in the tested materials, using the LECO TGA 701 thermogravimetric analyzer. The carbon and hydrogen contents were tested using the LECO TruSpec CHN elementary organic analyzer. The calorific value was determined using the LECO AC 500 isoperibolic calorimeter. Based on the research results, it was concluded that the use of the biomass torrefaction process improves its energy parameters. In the long term, this will affect the maintenance of the technical and operational efficiency of devices, installations, and power boilers compared to the co-combustion of fresh biomass. The greatest differences in results were recorded in the case of chlorine content. Carrying out detailed tests on the material immediately after its harvest showed that the content of this element was about 70% higher than in the case of torrefied raw material. The presence of chlorine in alternative fuels is responsible for the formation of chloride corrosion. Its content can be up to five times higher compared to conventional energy sources. The degree of risk of chloride corrosion of the selected elements of devices and installations is assessed on the basis of the so-called “chlorine corrosion index”.

Torrefaction of biomass is one of the most promising pretreatment methods for deriving biofuels from biomass via thermochemical conversion processes. In this work, the changes in physicochemical properties and morphology features of the torrefied corn stalk, the changes in physicochemical properties and morphology features of the torrefied corn stalk were investigated. The results of this study showed that the elemental content and proximate analysis of the torrefied corn stalk significantly changed compared with those of the raw corn stalk. In particular, at 300 °C, the volatile content decreased to 41.79%, while the fixed carbon content and higher heating value increased to 42.22% and 21.31 MJ/kg, respectively. The H/C and O/C molar ratios of torrefied corn stalk at the 300 °C were drastically reduced to 0.99 and 0.27, respectively, which are similar to those of conventional coals in China. Numerous cracks and pores were observed in the sample surface of torrefied corn stalk at the torrefaction temperature range of 275 °C–300 °C, which could facilitate the potential application of the sample in the adsorption process and promote the release of gas products in pyrolysis. In the pyrolysis phase, the liquid products of the torrefied corn stalk decreased, but the H2/CO ratio and the lower heating value of the torrefied corn stalk increased compared with those of the raw corn stalk. This work paves a new strategy for the investigation of the effect of torrefaction on the physiochemical characteristics and pyrolysis of the corn stalk, highlighting the application potential in the conversion of biomass.

The torrefaction process is widely used in the energy field, but the characteristics of the torrefied wood also have positive effects on the production of wood plastic composites. In this study, short-rotation shrub willow was torrefied at 225 and 300 °C and incorporated into polypropylene composites filled with changing levels of weight percent (wt%) of non-torrefied and torrefied (5, 15, 25, and 40 wt%) wood. Nine different formulations were extruded for mechanical, thermal, and water absorption properties. The tensile properties of composites were not affected by any level of torrefaction, while higher flexure properties were in favor of lower wt% of torrefied wood. The slowest rate of thermal degradation was confirmed for the highest wt% of torrefied wood with a torrefaction temperature of 300 °C. In contrast, the presence of torrefied wood in composites did not show a difference in crystallization or melting temperatures. The most noticeable contribution of torrefaction temperature and wt% was found for water-absorbing properties, where the higher torrefaction temperature and largest wt% of torrefied wood in the composite resulted in decreased water uptake.

The main objective of this review is to present the latest research results regarding the importance of the torrefaction process for different biomass materials in the last 12-year period. Despite the fact that the potential of renewable energy sources has been analyzed, research regarding that of energy derived from waste biomass still remains in the infancy state. Torrefaction is known to be one of the most effective methods for enhancing the energy efficiency of biomass. Among different types of torrefactions, the focus in this study is mostly on dry torrefaction. The influential factors, like temperature and residence time, and physico-chemical properties of torrefied products, and the prospective of torrefaction due to its reduced impact on environment, are discussed in-depth. This review provides valuable insights into the torrefaction process, which is conducive to upgrading biomass for achieving net zero carbon emissions, as it has been stated in several works that torrefied biomass can be used instead of coal.

The over-reliance on fossil fuels as a primary source of energy is partly responsible for the increase in carbon dioxide (CO2), depletion of the ozone layer, and general environmental pollution. In this study, torrefaction of Albizia zygia wood-calcium hydrogen phosphate (CaHPO4) catalyst blends was carried out in a tubular furnace to examine the impacts of temperature, time, and particle size on higher heating value (HHV) and energy yield (EY). Albizia zygia wood was obtained at an industrial sawmill junkyard nearby Kwara State University, dried, crushed, and sieved into 1 - 3 mm particle size. Optimal Combined Design (OCD) was employed for the design, modelling, and optimization of HHV and EY under the ranges of selected temperature (200 - 300°C), residence time (15 - 30 min), and particle size (1 - 3 mm) in an inert environment tubular furnace. The results of the analysis indicated that the temperature of 245°C, time of 22 min, and size of the particle 3 mm yielded a maximum HHV of 19.59 MJ/Kg and EY of 76.37% respectively. Also, the addition of catalyst (CaHPO4) at 10% reduced the ash content but enhanced the fixed carbon content of the biochar. The mathematical models for the HHV and EY for the torrefaction using the OCD imply an excellent fit with R2 of 0.92 and 0.96, respectively. The prediction accuracy indicates that OCD can be deployed for the accurate prediction of HHV and EY in torrified biomass.

The objective of this study is to examine the potential product yields and energy recovery of maize cobs (MC) through carbon dioxide-assisted torrefaction using thermogravimetric analysis (TGA). The CO2-assisted torrefaction of MC was performed from 240 °C to 300 °C (Δ 30 °C) for the residence time of 30 minutes based on the selected non-isothermal/isothermal heating program of the TGA. Furthermore, the physicochemical, microstructure and mineral characteristics of MC were examined. The results showed that the CO2-torrefaction of MC resulted in a mass loss (ML) ranging from 18.45% to 55.17%, which resulted in the mass yield (MY) ranging from 81.55% to 44.83%. The HHV of the solid product was in the range from 22.55 MJ/kg to 26 MJ/kg, which indicates the CO2-torrefaction process enhanced the energy content of MC by 40% – 60%. In conclusion, the findings showed that the CO2 torrefaction is a practical, sustainable, and cost-effective approach for the valorization of MC into a clean solid biofuel for enhanced energy recovery.

Thermochemical processes, which include pyrolysis, torrefaction, gasification, combustion, and hydrothermal conversions, are perceived to be more efficient in converting waste biomass to energy and value-added products than biochemical processes. From the chemical point of view, thermochemical processes are highly complex and sensitive to numerous physicochemical properties, thus making reactor and process modeling more challenging. Nevertheless, the successful commercialization of these processes is contingent upon optimized reactor and process designs, which can be effectively achieved via modeling and simulation. Models of various scales with numerous simplifying assumptions have been developed for specific applications of thermochemical conversion of waste biomass. However, there is a research gap that needs to be explored to elaborate the scale of applicability, limitations, accuracy, validity, and special features of each model. This review study investigates all above mentioned important aspects and features of the existing models for all established industrial thermochemical conversion processes with emphasis on waste biomass, thus addressing the research gap mentioned above and presenting commercial-scale applicability in terms of reactor designing, process control and optimization, and potential ways to upgrade existing models for higher accuracy.

Bio-oils produced from torrefaction or pyrolysis of biomass constitute an under-utilized product that generally requires complicated processing. The high acidity and water content pose storage and transportation issues, and the complex nature of the organic species makes utilization as a chemical feedstock troublesome. Most methodologies to separate and upgrade bio-oils involve multiple distinct steps and solvent-based extractions, complicating the process and adding cost. In this work, we demonstrate a simple one-step solution using ammonia to separate the aqueous and organic phases of a model bio-oil. This process produces an aqueous phase that contains ammonium species that could be utilized as a fertilizer and an organic phase that can be used as an additive for transportation fuels or could be burned to produce electricity.

In this study, the combustion characteristics and kinetics of various mixtures of both raw and torrefied rose pulp and red pine sawdust with each other and with Elbistan lignite were investigated in the context of lignocellulosic biomasses' potential use as fuel. Ignition temperatures, peak temperatures, burnout temperatures, and comprehensive combustion indexes of the fuel mixtures were found to rise with the torrefaction process. This finding indicates that the fuel/combustion performance of the waste biomass can be improved by the torrefaction process. Moreover, the combustion behavior of rose processing waste and pine sawdust has been significantly improved by adding lignite to the samples to be torrefied. Average activation energies of raw pine sawdust, rose processing waste, and Elbistan lignite were found to be 178, 187, and 91 kJ mol–1, respectively. However, the activation energies of both raw samples and their mixtures with lignite as well as each other decreased with the torrefaction process. Furthermore, a synergistic effect was also observed during the combustion of the mixtures of both raw and torrefied biomass with Elbistan lignite. [ABSTRACT FROM AUTHOR]

Torrefaction in partially oxidative atmospheres is a non-traditional approach to the thermal pre-treatment of biomass. Despite the potential benefits arising from this compared to traditional torrefaction undertaken under costly inert atmospheres, the literature lacks data on the combustion and kinetic analyses of densified biomass torrefied under partially oxidative conditions comparable to those of (reusing) combustion flue gases. This paper, therefore, investigates the effects of partially oxidative atmosphere on the chemical functionality, combustion kinetics and thermodynamics of densified (Australian) woody biomass. Torrefaction was conducted at 250, 275, 300 °C for 30min under both inert and partially oxidative atmosphere (O 2 : 5 vol%, N 2 balance). The kinetic parameters were derived from iso-conversional method over the entire conversion range. Results show that solid biofuel torrefied under partially oxidative atmospheres has superior chemical functionality (e.g., less oxygenates and higher thermal stability), but comparable physical properties to inert atmospheres. In addition, improved thermodynamic features and lower combustion activation energy for partially oxidative torrefied biomass was observed. Overall, the results suggest that the use of partially oxidative atmospheres for torrefaction not only produce a high quality solid biofuel but can also improve process efficiency by using waste heat and flue gases from other combustion processes to thermally pre-treat biomass. [ABSTRACT FROM AUTHOR]

Torrefaction is a promising pretreatment technology for valorizing biomass and upgrading pyrolysis products. This study sets out an original procedure consisting of subjecting the biomass to torrefaction before fast pyrolysis to increased value-added compounds based on agricultural waste biomasses production. This study uses a combined biomass treatment consisting of torrefaction (280–320 °C) and subsequent fast pyrolysis (500 °C) using the same reactor. Under different torrefaction temperatures and residence times, olive pomace (OP) and almond shell (AS) have been evaluated. The study demonstrated OP rather than AS was thermally unstable. The highest total yield of carboxylic acids (mainly acetic acid) was obtained by means of torrefaction at 280 °C with a residence time of 20 s for OP, and at 300 °C and 20 s for AS. Higher torrefaction temperature and residence time promoted phenolic compounds production for OP. However, OP had a higher lignin content and inherent metals that promoted a catalytic reaction during the procedure. The highest yield (47.7%) was obtained using torrefaction at 320 °C with a residence time of 240 s. Overall, the torrefaction of biomass combined with fast pyrolysis constituted a very simple and efficient strategy for valorizing the conversion of agricultural waste biomass into value-added chemicals. [ABSTRACT FROM AUTHOR]

The impact of torrefaction, alkaline pretreatment, and their combination on enzymatic hydrolysis was explored in terms of their effect on glucose yield from wheat straw. Samples were ground and torrefied at varying degrees of process severity, subjected to enzymatic hydrolysis, and analyzed for glucose yield. While glucose yield from raw biomass averaged 190.1 mg per g of dry raw biomass, the yield from torrefied samples was lower, ranging from 0.0 to 63.8 mg g-1, depending on the duration and temperature of the torrefaction process. Alkaline pretreatment increased the glucose yield of raw biomass to an average of 354.9 mg g-1. The highest glucose yield of 359.1 mg glucose g-1 was achieved for samples that were pretreated with a 1% NaOH solution. Alkaline pretreatment after torrefaction but prior to hydrolysis results in glucose yields ranging from 1.2 to 318.2 mg g-1, which are higher than the yields from torrefied-only samples but lower than those of raw, alkaline pretreated samples. When measured on a “per torrefied g” basis, yields of torrefied, alkaline pretreated samples approach those of raw biomass. These results indicate that there may be potential to use torrefaction and hydrolysis together when combined with an alkaline solution pretreatment. [ABSTRACT FROM AUTHOR]

The article describes the investigation of the torrefaction process of four samples of biomass (brewer's grains, sewage sludge, distillery stillage, and coffee grounds) in a fluidized bed in an environment of superheated steam at a temperature of 300°C and in a flue gas environment (oxidative torrefaction) at a temperature of 250°C. It has been established that the torrefaction of brewer's grains, distillery stillage and coffee grounds produces biochar with a higher carbon content and a higher calorific value than that of the raw biomass. In addition, it has been found that the best raw material for producing biochar among the studied biomass samples is coffee grounds; brewer's grains is somewhat inferior to it. It is not advisable to use sewage sludge and distillery stillage as raw materials for biochar production. [ABSTRACT FROM AUTHOR]

Microwave simulation is significant in identifying a reactor design allowing the biomass to be heated and processed evenly. This study integrated the radio frequency and transient heat transfer modules to simulate the microwave distribution and investigated the performance of microwave heating in the cavity. The simulation results were compared with the experimental findings using the finite element analysis software of COMSOL MULTIPHYSICS to predict the temperature profile and electric field of microwave in the biomass (empty fruit bunch pellets). The higher temperature distribution was observed at the bottom and centre section of the empty fruit bunch pellet bed in the reactor, showing the uniqueness of microwave heating. According to the simulation results, the temperature profile obtained through the specific cavity geometry and dielectric properties agreed with the experimental temperature profile. The simulated temperature profile demonstrated a logarithmic increase of 120 °C/min at the first 50 s followed by 50 °C/min until 350 s. The experimental temperature profile showed three different heating rates before reaching 300 °C, including 78.3 °C/min (50-120 °C), 30.6 °C/min (121-250 °C), and 105 °C/min (250-300 °C). The results of this study might contribute to the improvement of microwave heating in biomass torrefaction. [ABSTRACT FROM AUTHOR]

Biomass can be considered an alternative to coal in the production of heat and electricity. Many types of biomass are waste from agriculture and the food industry. This waste is cheap, readily available, and replenished annually. However, most agricultural and food industry wastes (sugar cane pulp, olive and sunflower oil production wastes, straw, etc.) have ash with a low melting point. This leads to a rapid growth of ash deposits on the heating surfaces of boilers; as a result, the actual efficiency of boilers in which waste from agriculture and the food industry is burned is 45–50%. Known biomass pre-treatment technologies that allow for the fuel characteristics of biowaste. For example, leaching of biowaste in water at a temperature of 80–240 °C makes it possible to drastically reduce the content of alkali metal compounds in the ash, the presence of which reduces the melting point of the ash. However, this biomass pre-treatment technology is complex and requires additional costs for drying the treated biomass. We proposed to use torrefaction for pre-treatment of biomass, which makes it possible to increase the heat of combustion of biomass, increase the hydrophobicity of biomass, and reduce the cost of grinding it. However, we are not aware of studies that have studied the effect of torrefaction on the chemical composition of ash from the point of view of solving the problem of preventing the formation of agglomerates and reducing the growth rate of ash deposits on the convective heating surfaces of boilers. In this paper, the characteristics of sunflower husk subjected to torrefaction in an environment of superheated steam at a temperature of 300 °C and in an environment of gaseous products at a temperature of 250 °C are studied. All experiments were conducted using fluidized bed technology. The resulting biochar has a calorific value of 14.8–23% higher than the initial husk. To assess the behavior of sunflower husk ash, predictive coefficients were calculated. Torrefaction of sunflower husks does not exclude the possibility of slagging of the furnace but reduces the likelihood of slagging by 2.31–7.27 times. According to calculations, the torrefaction of sunflower husks reduces the likelihood of ash deposits on the convective heating surfaces of the boiler by 2.1–12.2 times. According to its fuel characteristics, the husk, after torrefaction in an environment of superheated steam, approaches wood waste, i.e., can be burned separately without additives or mixtures with other fuels with refractory ash. [ABSTRACT FROM AUTHOR]

In the work presented, effective methods of biomass processing for its reuse in the framework of the circular economy were determined. Based on various sources, a definition of biomass was obtained. The review covers preliminary operations, i.e., screening and grinding, as well as the methods of pressure and non-pressure agglomeration of plant and animal biomass, as well as the process of torrefaction of plant biomass. The analysis of the literature indicates various process and technological solutions for biomass processing, as well as provides numerous examples of the use of biomass in combination with other types of industrial waste and mineral additives. The activities undertaken as part of the work are consistent with the assumptions of the European Green Deal and are carried out in order to improve the management of waste streams (green productivity) and to increase the amount of recovered energy produced. [ABSTRACT FROM AUTHOR]

To maximise the use of biomass for energy purposes, there are various options for converting biomass to biofuels through thermochemical conversion processes, one of which is torrefaction. Higher utilisation of waste from the aspiration cleaning of grains, such as wheat or maize, could be one of the means through which the dependence on fossil fuels could be reduced in the spirit of a circular economy. In this study, the effect of torrefaction on fuel properties of agricultural residues was investigated. The tested materials were waste by-products from the aspiration cleaning of maize grains and waste from wheat. The materials were treated by torrefaction under a nitrogen atmosphere (225 °C, 250 °C, and 275 °C), over a residence time of 30 min. During the treatment, weight loss was monitored as a function of time. Proximate and elemental composition, as well as calorific values, were analysed before and after torrefaction. Torrefaction has a positive effect on the properties of the fuels in the samples studied, as shown by the results. The carbon content increased the most between temperatures of 250 °C and 275 °C, i.e., by 11.7% wt. in waste from maize. The oxygen content in the maize waste samples decreased by 38.99% wt. after torrefaction, and in wheat waste, it decreased by 37.20% wt. compared to the original. The net calorific value increased with increasing temperatures of process and reached a value of 23.56 MJ·kg−1 at a peak temperature of 275 °C in by-products from maize. To express the influence of the treatments on combustion behaviour, stoichiometric combustion calculations were performed. Differences of up to 20% in stoichiometric combustion parameters were found between the two types of waste. A similar case was found for fuel consumption, where a difference of 19% was achieved for torrefaction at a temperature of 275 °C, which fundamentally differentiated these fuels. [ABSTRACT FROM AUTHOR]

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The biorefinery concept is growing rapidly for bio-based production of fuels and products, and steam explosion is by far the most applied pre-treatment technology allowing the delignification of lignocellulosic biomass. Within the bioethanol production process, pyrolysis of lignin-rich residue (LRR), for producing char to be used in a wide variety of applications, presents a viable way to recover materials and energy, helping to improve the sustainability of the whole production chain. In the present study, it is shown that yields, elemental composition and porosity characteristics of LLR-char are significantly different from those of char produced from alkali lignin. Both products yields and char composition were more similar to the typical values of woody and herbaceous biomasses. The chemical characterization of the chars' organic matrices as well as the content of the main inorganic species suggest the opportunity to perform pyrolysis at low temperatures for producing high yields of chars suitable to be used as carbon sink or soil fertilizers. The BET values of the chars obtained at final temperatures in the range 500–700 °C seem to be promising for char-application processes involving surface phenomena (e.g., adsorption, catalyst support), thus encouraging further analyses of char-surface chemistry. [ABSTRACT FROM AUTHOR]

Solid biofuels produced from torrefaction have improved coal-like properties in comparison to raw biofuels, yet ensuring uniform product quality is still a challenge. In this study, downstream torrefaction of wood pellets was performed at temperatures between 200 and 270 °C in a rotary kiln reactor to understand the effect of torrefaction temperature on product quality. The torrefied solid biofuel was compared with dedicated fuel properties defined in ISO/TS 17225-8:2016-12. Based on the results, the optimal temperature for downstream torrefaction was found at temperatures of 230 and 250 °C. Above this temperature, the effect of bulk density superimposes not only the increased net calorific value but also values for mechanical durability, amount of fines, and bulk density of the solid biofuel, which were below the thresholds of the fuel standard. Moreover, increasing process temperatures caused higher heavy metal concentrations in torrefied pellets. The composition of condensable and non-condensable fractions of the torr-gas substantially increased between temperatures of 230 and 250 °C and remained on a similar level at higher temperatures. Thus, the utilization of torr-gas for energy recovery purposes and as a precursor for the recovery of valuable chemicals should be balanced with the quality of the solid biofuel in the aforementioned range of torrefaction temperatures to enable the utilization of torrefaction products at further steps. [ABSTRACT FROM AUTHOR]

Raw and torrefied rice hulls (RRH and TRH) were incorporated into polyhydroxybutyrate (PHB) as fillers using extrusion and injection molding to produce biomass-polymer composites. Filler and composite materials were characterized by particle size analysis, thermomechanical analysis, thermogravimetric analysis, differential scanning calorimetry, FTIR analysis, CHNSO analysis, and mechanical testing. Heat distortion temperature of the RRH composites were 16–22 °C higher than TRH composites. The RRH composite samples showed a 50–60% increase in flexural modulus and 5% increase in stress at yield compared to PHB, while TRH composite samples showed nearly equal flexural modulus and a 24% decrease in stress at yield. The improved mechanical properties of the RRH composites in comparison to TRH composites were due to better particle-matrix adhesion. FTIR analysis showed RRH particles contained more surface functional groups containing oxygen than TRH particles, indicating that RRHs should be more compatible with the polar PHB plastic. SEM images showed space between filler and plastic in TRH composites and better wetted filler particles in the RRH composites. [ABSTRACT FROM AUTHOR]