Apricot Shell Research Articles

Synthesis of SiC nanowires from retired wind turbine blades and their microwave-absorbing property

Retired wind turbine blades (RWTBs) mainly consist of glass fibers and resins, which have abundant of carbon and silicon resources. This study synthesized SiC nanowires (SiC NWs) by using the RWTBs for the first time. The RWTBs were grinded into powders and pyrolyzed at 600 °C for 2 h, the pyrolysis solid residues (P-RWTBs) mixed with apricot shell char (ASC) and silicon powder in a stoichiometric ratio (C/Si=4), and then the mixture calcined at 1550 °C for 4 h in an argon atmosphere. XRD, FTIR and XPS results indicating that SiC NWs had been successfully synthesized. SEM and TEM micrographs show that the produced SiC NWs exhibit a worm-like shape, with diameters of 50–100 nm, and interweave into a 3D network body. The minimum reflection loss (RLmin) of the SiC NWs 3D network body reached -18.17 dB at the thickness of 4.8 mm, which meet the requirements of microwave-absorbing materials. Its good microwave-absorption property is due to the various loss types of the electromagnetic waves that caused by the special structure. This study provides a new approach for high-value utilization of the RWTBs, which is of great significance in realizing the "green retirement" of glass fiber reinforced polymers.

Investigation on the oil permeation–adsorption–diffusion combined action mechanism of the adsorbed layer for flexible oil storage in waters

A novel method entitled flexible oil storage in waters is proposed, aiming to address the limitations of current oil storage systems and enhance the country's oil storage capacity. However, oil contamination severely restricts its applicability. To ensure the environmental sustainability of the method, the adsorbed layer is added outside the oil bladder, and the study investigates the material and the action mechanism of the adsorbed layer for flexible oil storage in waters. The results show that, with long breakthrough time and low oil concentration as criteria, the reed straw biochar is more suitable as the adsorbed layer filling material compared to the coconut shell and the apricot shell biochar and the fluorinated ethylene propylene copolymer is more suitable as the adsorbed layer membrane material compared to polyvinyl chloride. The adsorbed layer action mechanism involves multiple interactions, including permeation, adsorption, accumulation, and diffusion. They are coupled and together influence the adsorption effect. The empirical formula for the adsorbed layer's lifespan is derived, which helps in designing the adsorbed layer to satisfy specific lifespan requirements. This study provides theoretical and engineering guidance for the application of flexible oil storage in waters, contributing to the development of oil storage techniques.

Experimental study on hydrogen production from heavy tar in biomass gasification furnace catalyzed by carbon-based catalysts

High boiling point heavy tar compounds such as pyrene and naphthalene are key factors causing corrosion and blockage in the pipelines of biomass thermal utilization equipment, and catalytic reforming represents an effective means to address heavy tar issues. Biomass carbon, characterized by its cost-effectiveness, high efficiency, and environmental friendliness, is envisioned as a catalyst carrier with extensive application prospects. In this study, the tar produced by a biomass fixed-bed gasifier was investigated, with an initial analysis of the pyrolysis process and definition of its different stages conducted. It was discovered that the condensation and secondary cracking stages are the predominant phases for the formation of heavy tars, including polycyclic aromatic hydrocarbons (PAHs). Carbon-based carriers were prepared using apricot shell as the raw material, and biomass carbon-based catalysts were synthesized via impregnation methods. The heavy tar extracted from the original tar through distillation was utilized in the hydrogen production tests of steam catalytic reforming with biomass carbon-based catalysts. The investigation into the impact of temperature, steam-to-tar mass ratio (S/T), and tar-to-catalyst mass ratio (T/C) on the catalytic reforming of tar has been conducted. In considering a variety of parameters, including hydrogen production rate, tar conversion rate, and the volume of hydrogen generated, it was found that under the conditions of 800 °C, S/T = 3, and T/C = 2, the Ni/C catalyst yielded the highest amount of hydrogen (91.52 g H2/kg tar) with a tar conversion rate of 93.30 %. The Ni-Co/C composite catalyst exhibited stronger catalytic activity and superior deactivation resistance compared to the monometallic catalysts. For the latter, steam regeneration methods effectively restored the catalytic activity of the carbon-based catalysts, enhancing the hydrogen yield rates of Ni/C and Co/C catalysts by 2.74 and 1.55 times respectively.

Determination of Mechanical Properties of Fruit Shell Powders Reinforced Wood Plastic Composite (WPC) Materials and Case Study for I-Type Snap-Fit Model

High quality material production has been among the work of many researchers in recent years. These materials, which are obtained mostly by the production of composite materials, enable the production of lighter, more durable and less costly products. Increasing environmental pollution in recent years, protection of natural resources and ensuring recycling have increased the importance of wood plastic composite material production. In this study, wood plastic composite material was obtained by using ABS (Acrylonitrile butadiene styrene) plastic material and six different fruit shell powders (walnut, pistachio, peanut, almond, hazelnut and apricot shell). The mechanical properties of the obtained composite material were determined and its effect on the I type snap-fits was analyzed in ANSYS software. When the resulting composite material's mechanical properties were tested, it was found that the density and tensile strength decreased while the Vicat softening point value and melt flow rate increased. In the analysis performed using the ANSYS software, it was found that the composite I type snap-fit design of the same size can resist 12.6% N less force when the material is subjected to its maximum values when it achieves the elongation at break value.

Grafted natural melanin κ-carrageenan hydrogel bead adsorbents: New strategy for bioremediation of cationic dye contamination in aqueous solutions

Pollution of water resources has become a global environmental problem, and the massive discharge of high-color printing and dyeing wastewater has caused serious harm to the natural environment. In this work, we have used repeated alkali solubilization and acid precipitation for an agricultural and forestry by-product, bilberry kernel shells, to obtain Mountain apricot shell Melanin (Mas-Mel), which can be used for the adsorption of cationic dyes. By graft copolymerization with a natural sugar-based polymer, κ-carrageenan (κCA), in a mild manner, we have prepared the adsorbent, Mountain apricot shell Melanin /κ-carrageenan (Mas-Mel/κCA) hydrogel beads, which were physically and chemically analyzed using a variety of spectroscopic and microscopic techniques. The optimum conditions for methylene blue (MB) adsorption and malachite green (MG) on Mas-Mel/κCA hydrogel were: contact time 150 min, adsorbent dose 60 mg, pH 6–7. The results of the adsorption tests followed the Pseudo-second order kinetics (R2 = 0.97 and 0.95), and the maximum adsorption capacity of MB and MG based on the Langmuir isotherm model was 48.63 mg/g and 37.84 mg/g, respectively. In addition, the prepared hydrogel beads still exhibited a high reusability and removal rate (∼50 %) after three consecutive 400-minute cyclic adsorption-resolution cycles. Our results may provide a new strategy for the development of green bio-based adsorbent materials and industrial dye wastewater treatment.

Synthesis, Design and Evaluation of Innovative Combined Nano-Catalysts Supported on Activated Carbon Prepared from Apricot Shells

Abstract: Clean fuel oil is crucial for a healthy environment and modern life. Therefore, removing sulfur-containing compounds is an effective issue using various techniques for desulfurization. In this study, the oxidation desulfurization (ODS) process was utilized with respect to the prepared new activated carbon (AC) made from apricot shells (AS) loaded by two combined active metals (Nickel-Cobalt-Manganese (NCM) and Nickel-Cobalt-Manganese-Molybdenum (NCMM)). Several characteristics related to the catalysts prepared (mainly SBET, pore volume, FTIR, TGA, SEM, EDX and XRD) have been investigated to analyze the produced nanocatalysts. The new nanocatalysts (NCM/AC and NCMM/AC) were generated by using the impregnation wetness incipient (IWI) method and evaluated for their ability to remove sulfur compounds from whole-cut fuel (from 29-345 °C) based on the air as an oxidant within batch reactor under the following conditions: air flow rate = 2 lit/min, reaction temperature = 90 °C, and reaction time of 60 min for both catalysts. It was found that Nano catalyst NCMM/AC performed better overall in removing sulfur components (57.29 %) than Nano catalyst NCM/AC (44.75 %), and excellent properties have been observed.

Design of Highly Efficient Nickel-Cobalt-Manganese-Molybdenum (NCMM) Nano-Catalysts Supported on Activated Carbon for Desulfurization Process

To maintain a healthy environment and way of life in the modern world, clean fuel must be produced. It is important to totally and successfully remove sulfur-containing harmful compounds from fuel oil in order to comply with the new sulfur legislation. Numerous methods have been proposed in the literature for desulfurizing fuel oil. In this study, activated carbon (AC), which is regarded as a significant porous material, is derived from agro-wastes such as apricot shells (AS) and is loaded with different combinations of active metals. Nickel–Cobalt–Manganese (NCM) over AC is firstly prepared and evaluated experimentally. Then, several concentrations of Molybdenum (1%, 2% and 3%) are separately added to NCM to generate three novel composite mesoporous nano-catalysts (NCMM_1, NCMM_2 and NCMM_3). Several tests have been carried out to determine the catalysts’ properties, such as BETsurface area, pore volume, FTIR, TGA and SEM, XRF and XRD. These catalysts are then used in the batch oxidative desulfurization process to remove sulfur compounds from wide cut oil (from IBP to 345 °C). The pilot plant conditions were as follows: air flow rate = 120 L/h, reaction temperature = 363 K and reaction time of 1 h for all catalysts. Remarkable characteristics have been noticed, and it was discovered that the nano-catalyst NCMM_2 performed better in terms of degree of sulfur removal compared to other nano-catalysts.

Enhanced Cr(VI) Adsorption from Water by Reactivation Treatment of Apricot Shell Activated Carbon

The pore structure of apricot shell activated carbon was changed by reactivation treatment. The influence of reactivation treatment of activated carbon on the adsorption of hexavalent chromium [Cr(VI)] from water was investigated under different conditions. The results show that the reactivation treatment enriches the pore structure of activated carbon and increases the pore size. When pH is under 4, the reactivation treatment of activated carbon does not cause a significant difference in the adsorption amount of Cr(VI) compared with untreated activated carbon. However, it is obviously contribute to Cr(VI) adsorption solution when pH is more than 4. In the same adsorption temperature, adsorption time, solution pH, and ratio of activated carbon to Cr(VI), reactivated activated carbon shows higher Cr(VI) adsorption capacity in aqueous solution than the untreated activated carbon, and maximum Cr(VI) removal rate of the reactivated activated carbon reaches 99.83%.

Preparation of biomass-waste-derived carbon dots from apricot shell for highly sensitive and selective detection of ascorbic acid

• Low-cost synthesis of CDs was firstly achieved with biomass-waste apricot shell • The CDs showed good fluorescent response towards AA in the Fe 3+ -CDs system • A fluorescent sensor for AA was successfully fabricated based on CDs • The AA sensor is applicable for sensitive detection of H 2 O 2 in real samples An ascorbic acid (AA) fluorescence sensor was built using biomass-waste-derived carbon dots (CDs). The CDs were prepared using apricot shell biomass, which serves as an abundant starting source. The prepared CDs displayed good dispersion, uniform particle size, high photostability, and a greenish-yellow luminescence. The experimental results confirmed the greenish-yellow fluorescence was selectively quenched by Fe 3+ and then recovered selectively upon adding AA to the Fe 3+ -CD system, exhibiting an off-on phenomenon. The recovered fluorescence intensity was linear with AA concentration. The linear range is 1-100 μM and detection limit is 40 nM. Analysis of a real sample was also carried out to determine the AA content in human urine. The proposed strategy allowed efficient use of discarded apricot shells that have good economic, environmental, and medical benefits.

Metabolomics Data Revealed Metabolite Changes during Endocarp Lignification in Kernel-Using Apricot

To understand the metabolite dynamics and genetic regulatory mechanism of apricot shell, a typical endocarp, before and after lignification are unknown, we investigated the metabolite differences of the endocarp of ‘Youyi,’ a popular kernel-using apricot cultivar, using ultra-performance liquid chromatography tandem mass spectrometry strategy. The endocarp thickness increased rapidly from 8 to 37 days after flowering (DAF) and lignin deposition began at 37 DAF. In total, 626 non-volatile metabolites were obtained from the endocarp tissues before (33 DAF) and after (41 and 45 DAF) lignification. The relative sugar and organic acid contents decreased continuously and those of L-phenylalanine and L-tyrosine increased after lignification. In the non-lignified endocarp, the phenylpropanoid metabolites were mainly in the form of p-coumaric acid, ferulic acid, neochlorogenic acid, dicumarol, coniferin, and some lignans. After lignification, the metabolites were mainly in the form of glycoside lignin or lactone coumarins, and the relative contents of L-asarinin and forsythin increased. The results of transcriptome confirmed the upregulation of genes related to lignin biosynthesis, including β-glucosidase and coniferyl-alcohol glucosyltransferase and laccases, accelerated lignification. This study provides insights into the formation of lignified endocarp in a kernel-using apricot and clarifies the role of monolignin transport and oxidative polymerization.

Comparative study on pyrolysis kinetics of agroforestry biomass based on distributed activation energy model method

Pyrolysis behavior and kinetics of three typical agroforestry biomasses including apricot shell, wheat straw and poplar sawdust were investigated by thermogravimetric mass spectrometry (TG-MS). The results show that the differences of the main components make the three biomasses exhibit different characteristics in the main reaction range (200–450 °C). It is found that the average activation energy of apricot shell, straw and sawdust is 188.22, 220.77, and 175.87 kJ/mol, respectively based on the typical isoconversional methods. The average activation energy of each component in biomass was calculated by the distributed activation energy model (DAEM) method, indicating that there is a fourth component with high average activation energy in biomass (297.44 kJ/mol for apricot shell, 284.35 kJ/mol for straw and 309.96 kJ/mol for sawdust). The activation energy of hemicellulose and cellulose shows an increasing order of straw < apricot shell < sawdust. The two kinds of kinetics methods are complementary to each other. The overall calculation results by the isoconversional method are close to those by the single-component distributed activation energy model method, but the isoconversional method is simpler; while the distributed activation energy model method can be used to obtain the kinetic parameters of different components of raw materials, which makes up for the deficiency of the isoconversional method. A combined use of the two methods can form a more comprehensive understanding of the pyrolysis reaction.

Preparation and Characterization of Apricot Kernel Shell Biochar and Its Adsorption Mechanism for Atrazine

In this study, the preparation of apricot kernel shell biochar by a hydrothermal method and its adsorption mechanism for atrazine was studied by scanning electron microscopy (SEM) and infrared spectrum (FTIR) analytical techniques. The results show that the biochar prepared from the apricot kernel shell has an evenly distributed, nonaggregated carbon microsphere structure and contains a large number of oxygen-containing groups. The higher the preparation temperature is, the more functional groups exist and the better the potential adsorption performance is. The adsorption kinetics of atrazine on apricot kernel shell biochar were fitted with a quasi-second-order kinetic equation (R2 ≥ 0.995, p &lt; 0.05). The isothermal adsorption data were in accordance with the Freundlich model (R2 ≥ 0.911, p &lt; 0.05). The adsorption of atrazine on apricot kernel shell biochar includes two processes: surface adsorption and diffusion. The adsorption capacity of apricot kernel shell biochar for atrazine increases with increasing preparation temperature and decreases with increasing pH and Ca2+ concentration. The adsorption mechanism includes hydrogen bonding and hydrophobic interactions. Therefore, biochar prepared from apricot shells, an agricultural waste, exhibits good adsorption performance for atrazine and has a good application prospect in addressing agricultural non-point source pollution, especially in pesticide residue pollution control.

Sorption mechanisms of diethyl phthalate by nutshell biochar derived at different pyrolysis temperature

The sorption properties of diethyl phthalate (DEP) by four series of biochar samples produced from apricot shell, coconut shell, peanut shell and walnut shell at 300–800 ℃ were investigated. The morphology, physical structure and chemical composition of biochar were characterized by SEM, N2 and CO2 adsorption-desorption isotherms, elemental analysis, 13C NMR, FTIR and TGA, showing that with the increase of pyrolysis temperature, the yield and polarity of biochar decreased, while the aromaticity increased. All the sorption isotherms were fitted by Freundlich model and exhibited highly nonlinear with n ranging from 0.16 to 0.55. Compared with higher-temperature biochar (HBCs, 500–700 ℃), the lower-temperature biochar (LBCs, ≤ 400 ℃) had stronger sorption intensity in each series due to specific interaction (e.g. hydrogen bonding) between the polar functional groups in LBCs (ASBs, WSBs and PSBs) and DEP molecules. Differently, the sorption interactions between HBCs and DEP were mainly driven by the surface adsorption at the energy sites and the 800 ℃-derived biochars with high specific surface area (415.13–454.17 m2/g) were the strongest in the same series. Peanut shell derived-biochar with higher Koc (Ce=0.1Sw) values of 358–3670 L/kg had excellent sorption performance, suggesting its promising potential for remediation of DEP in the environment. CapsuleThe underlying sorption mechanisms of diethyl phthalate (DEP) by four series of nutshell biochar derived at different pyrolysis temperature (300–800 ℃) were investigated.

Sustainable synthesis of apricot shell-derived hierarchical porous carbon for supercapacitors: A novel mild one-step synthesis process

Development for sustainability and renewable energy storage equipment with energy-efficient and environmentally-friendly characteristics being the overwhelming imperative problem that needs to be addressed. Here, apricot shells were used to prepare apricot shell-derived porous carbons (APCs) with hierarchical structures by employing a mild one-step method, viz. a CaCO3/K2C2O4 salt activator at 700 ℃. Pore structures for APCs can be regulated by the weight ratio of CaCO3 to K2C2O4. Significantly, the mild one-step preparation of APCs bypasses high temperatures (> 700 ℃), strong acids or alkalis, and supercritical drying or freeze-drying. The resultant optimal porous carbon APC-1 had a large specific surface area of 2348.96 m2/g and a low ratio (36.15%) of micropore volume (Vmicro) to total pore volume (Vtotal). Besides, APC-1 achieved a high specific capacitance of 300.41 F/g at 1 A/g in the three-electrode configuration and good capacitance retention of 85.88% at 10 A/g. Particularly, APC-1 displayed a high energy density of 29.54 Wh kg−1 upon 2800.83 W kg−1 in the two-electrode cell and excellent cycling stability of 91.56% capacitance retention after 10,000 cycles at 10 A/g. The present investigation gives a mild one-step approach to obtain biomass-derived porous carbons for high-performance supercapacitors.

Removal of Calcium over Apricot Shell Derived Activated Carbon: Kinetic and thermodynamic study

The apricot shells (AS) derived activated carbon (AC) was employed in removing the water hardness ions (calcium) from synthetic hard water. The ZnCl2 activation route was implemented in synthesizing the AC from the AS. The typical AC sample was diagnosed for its morphology by the FESEM technique, elemental analysis using EDX technique, influential surface groups by FTIR spectroscopy, and crystallinity by the XRD. This AC sample was then applied to eliminate the calcium ion (Ca+2) from synthetic hard water by investigating factors affecting the Ca+2 removal efficiency, like the solution pH, Ca+2initial concentration, AC dosage, temperature, and contact time. The outcomes revealed that Ca+2 removal by the so-synthesized AC is pH, temperature, and time-dependent. The best Ca+2 removal % reached 80.12 %, while the best adsorption capacity was 70.42 mg/g. The Langmuir adsorption isotherm and the pseudo-second-order kinetic model demonstrated were best described Ca+2 removal by the AC. The enthalpy and Gibbs free energy functions indicated that Ca+2adsorption is endothermic and spontaneous. Thus, the consequences assured that the ASs derived AC can be exploited as an effective adsorbent to remove Ca+2from the solution.

Preparation of porous biochar and its application in supercapacitors

In this study, economical porous biochar was prepared from an apricot shell and used as an electrode material for a supercapacitor, showing excellent capacitance, cycling stability and rate performance.

Creep characteristics and constitutive model of bio-based concrete in aqueous environment

Bio-based materials generally have high porosity, which are prone to biodegradation during the long-term application, especially in a humid environment. To better understand the impact of the aqueous environment on creep performance of bio-based concrete, the effects of the loading method (single-stage and multi-stage), axial force (50 kN, 100 kN, 150 kN), and water pressure (1 MPa, 2 MPa, 3 MPa) on the long-term creep characteristics of bio-based apricot shell concrete are investigated in this study, with a creep duration of up to 1051 h. The results show that water pressure has a significant effect on the creep properties of apricot shell concrete. The creep strain and creep rate of apricot shell concrete gradually decrease with the increase of water pressure, which attributes to the water confining pressure that restrains the propagation of micro-cracks and consequently reduces the creep strain. Moreover, the creep strain and creep rate of apricot shell concrete increase with the increase of axial force. The creep behavior of bio-based apricot shell concrete in low load level is well described by a proposed Burgers piecewise creep model, which is recommended to express the long-term creep behavior of bio-based apricot shell concrete in the aqueous environment.

Valorization of lignin: Application of lignin-derived activated carbon in capacitors and investigation of its textural properties and electrochemical performance

This work provides an idea for the efficient and harmless utilization of lignin and further evaluates the textural properties of lignin-derived activated carbon/specific capacitance relationship. The yield of apricot shell lignin (ASL) was 30.42%. H3PO4/KOH was used to assist the preparation of ASL-derived activated carbons (AACs) for capacitors. The AAC prepared at a ratio of H3PO4 weight to ASL weight of 3 (AAC-P-3) had a specific surface area of 1475.16 m2/g. Similarly, the AAC obtained at a ratio of KOH weight to ASL weight of 2 (AAC-K-2) owned a specific surface area of 2136.56 m2/g. At 0.50 A/g, the specific capacitance of AAC-P-3 and AAC-K-2 was 169.14 F/g and 236.00 F/g, respectively. The average value of the correlation coefficients (AR2) between specific surface area and specific capacitance was highest, i.e., 0.983, followed by the AR2 (0.978) between Vmicro/Vmeso and specific capacitance, the AR2 (0.975) between pore-wall thickness and specific capacitance. Consequently, when using a current density range of 0.50–10.00 A/g and a three-electrode configuration with a 6 M KOH electrolyte, the specific capacitance of AACs depends not only on the specific surface area but also on the Vmicro/Vmeso, pore-wall thickness, and Vmicro.

Upgrading biochar by co-pyrolysis of heavy bio-oil and apricot shell using response surface methodology

In this study, heavy bio-oil (HB) and apricot shell (AS) were used as raw materials to produce biochar by co-pyrolysis in a tube furnace. Three operational factors were assessed, namely pyrolysis temperature (400–700 °C), residence time (5–20 min) and percentage of HB (0–100%), with the effects on the yield and properties of biochar comprehensively investigated using a response surface methodology. Results showed that the mass yield, fixed carbon content, carbon content, and high heating value (HHV) of co-pyrolysis biochar (550 °C, 12.5 min, and an AS/HB mass ratio of 1:1) were 29.33%, 81.84%, 82.91%, and 32.97 MJ/kg, respectively. The experimental values for the co-pyrolysis biochar were 1.52%, 5.30%, 1.82%, and 1.12 MJ/kg higher than their corresponding theoretical values, respectively. However, the oxygen content of co-pyrolysis biochar was 1.71% lower than the theoretical value. Meanwhile, the C/H ratio of biochar improved with increasing pyrolysis temperature, residence time and percentage of HB, indicating higher biochar aromaticity. The evolution of surface functional groups indicated that an increase in pyrolysis temperature and residence time reduced the intensity of CO and C–O absorption peaks, while an increase in the percentage of HB enhanced the intensity of the C–O absorption peak of biochar. In general, compared to the pyrolysis of HB and AS alone, co-pyrolysis of HB and AS exerted a synergistic impact, improving the mass yield and fuel quality of biochar. Finally, the relationships between properties (mass yield, element content, proximate analysis parameters, and HHV) and the three varied factors were established, providing guidance for effective upgrading of biochar by co-pyrolysis of HB and biomass.

Effects of Torrefaction on the Lignin of Apricot Shells and Its Catalytic Conversion to Aromatics.

Using apricot shell lignin as a raw material, the effects of torrefaction temperatures (160, 200, 240, and 280 °C) on the properties of torrefied products were studied, and the catalytic pyrolysis experiments of the torrefied lignin under the HZSM-5 catalyst were carried out. The results showed that the oxygen content in lignin was greatly reduced and the higher heating values (HHV) gradually increased, the absorption peak of oxygen-containing functional groups gradually became weaker, and the content of the β-O-4 bond gradually decreased. At 280 °C, the C/O ratio reaches the maximum value of 2.17, and the calorific value increases to 24.22 MJ/kg. The removed oxygen element is converted into oxygen-containing components in the gas (mainly CO2 and H2O) and liquid products (mainly guaiacol phenol). After catalytic pyrolysis of torrefied lignin, it was found that with the increase of torrefaction temperature, the relative content of aromatics increased first and then decreased slightly; the aromatics reached the maximum value of 60.63% at 240 °C; acids decreased significantly; ketones, aldehydes, and furans changed little; and torrefaction played a positive role in the conversion of lignin to aromatics.