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• Phosphorus in rice straw mainly exists in OP and NAIP, and K as WSK. • By high temperature pyrolysis, more HCl-P was converted from OP and NaOH-P. • The volatilization was mainly at 200–500 °C for P and 500–900 °C for K. • The most suitable for use as P and K fertilizer was the 600 °C biochar. Biochar is an excellent soil amendment, but its fertilizer effect on the soil is often overlooked. In this study, a series of experiments were conducted to investigate the form changes of P (phosphorus) and K (potassium) in rice straw biochar at different pyrolysis temperatures and explore its fertilizer effect characteristics. The results showed that in the rice straw, P was mainly in the form of OP (organophosphorus) and NaOH-P (NaOH extractable phosphorus), and K as WSK (water-soluble potassium). For biochars, the various forms of P at 100–200 °C and K at 100–300 °C were basically unchanged; OP in rice straw biochar decreased gradually from 200 °C to 800 °C; at 200–1000 °C, NaOH-P in biochar gradually decreased, with 9.1 % of P (wt%) at 1000 °C; HCl-P (HCl extractable phosphorus) with more bioavailable, which was mainly converted from NaOH-P and OP, increased gradually from 6.8 % to 50.9 % for P (wt%) at 200–1000 °C. At 100–500 °C, the change of TK (total potassium) was slight; from 500 °C to 900 °C, WSK decreased from 84.7 % to 23.2 % for K (wt%); at 700–1100 °C, the ASK (acid-soluble K) was relatively high, with K (wt%) of 10.6–11.6 %. The volatilization was mainly at 200–500 °C for P and 500–900 °C for K, which volatilization rates were 5.6–30.3 % and 6.3–58.9 %, respectively. Moreover, HCl-P increased from 0.167 mg/g for the raw straw to 4.554 mg/g for the 1000 °C biochar and TK from 3.632 mg/g for the rice straw to 20.91 mg/g for the 600 °C biochar. It can be concluded that the biochars at 400–700 °C were suitable for use as a slow-release P fertilizer and K fertilizer. This work provides a strong basis for using a rice straw biochar at different temperatures as a P and K fertilizer. Capsule: By pyrolysis, the rice straw biochar contains more HCl-P and TK, and can be used as slow-release P fertilizer and K fertilizer. [ABSTRACT FROM AUTHOR]

[Display omitted] • Direct transforming raw straw to electricity and H 2 using yeast C. slooffiae JSUX1. • The MFCs delivered a power density of 28.56 mW/m2 and H 2 of 4.9 L/m3. • The enzymes secreted by the yeast JSUX1 consumed raw straw to electricity. • Humic acids derived from raw straw consumption served as electron mediators for MFCs. Lignocellulosic waste is one of the most abundant renewable energy sources. However, pretreatment or complex microbial consortia are usually required for the biological transformation into energy products. This study demonstrates the direct transformation of raw rice straw biomass into electricity and hydrogen without any pretreatment by employing a single yeast strain, Cystobasidium slooffiae JSUX1, in microbial fuel cells (MFCs). The yeast-MFCs exhibit a maximum power density of 28.56 ± 2.54 mW/m2 with simultaneous production of hydrogen gas (4.9 ± 0.52 L/m3) from raw straw. Further analysis reveals that enzymes secreted by the yeast strain degraded rice straw into sugars or organic acids, serving as fuel for electricity and hydrogen production. In addition, humic acid (HA) and Fe-HA derived from biomass consumption serve as electron mediators for extracellular electron transfer (EET) in MFCs. This study demonstrates the power of the yeast strain for renewable energy recovery from straw, diversifying the toolbox for the lignocellulose industry. [ABSTRACT FROM AUTHOR]

• Cu modified activated carbon (AC) and HZSM-5 (Cu/AC, Cu/HZSM-5) were prepared. • Microwave catalytic co-pyrolysis of Chlorella vulgaris and rice straw was studied. • Cu modified catalysts promoted bio-oil yield and reduced bio-gas yield. • 4 wt% Cu/HZSM-5 (10 % addition) obtained the highest hydrocarbon yield in bio-oil. • The highest bio-oil yield (32.13 %) was obtained at 1 wt% Cu/AC (10 % addition). The weight loss characteristics, production distribution, and quality of bio-oil could be improved through catalytic co-pyrolysis of rice straw (RS) and Chlorella vulgaris (CV) under modified catalysts. Therefore, modified catalysts Cu/AC (activated carbon) and Cu/HZSM-5 were proposed. In this study, the effects of Cu/AC and Cu/HZSM-5 as modified catalysts on the microwave catalytic co-pyrolysis (CV : RS = 7:3) at different Cu loadings (1 wt%, 4 wt%, 7 wt%) and additive amounts (5 %, 10 %, 20 %, 30 %) were investigated. The results revealed that Cu/AC and Cu/HZSM-5 positively influenced bio-oil production and selectivity of hydrocarbons, but also prolonged the reaction time. At 10 % addition, 1 wt% Cu/AC exhibited the highest average weight loss rate (R a) and the highest production of bio-oil (31.13 %). For Cu/HZSM-5, the highest production of bio-oil (28.37 %) was obtained with 7 wt% Cu/HZSM-5. Remarkably, the hydrocarbon content (57.22 %) in the bio-oil obtained from 4 wt% Cu/HZSM-5 was the highest among all groups. [ABSTRACT FROM AUTHOR]

• Constructed dynamic model simulates biomass degradation and microbial metabolism. • Model adapts kinetic parameters to temperature, humidity, and moisture changes. • New GA-PSO algorithm developed for efficient model parameter tuning. • Tremier model accurately predicts cellulose-rich, lignin-low biomass degradation. • CTMI and SRTM models excel in predicting microbial growth. In modern bioenergy, the long-term storage of substantial quantities of biomass is necessary. A critical issue arises from the potential self-heating of biomass piles initialized by exothermic microbial activities, which could result in spontaneous ignition. To address this concern, we develop a comprehensive dynamic model to accurately simulate biomass degradation and microbial metabolism. The model encompasses four key processes: the conversion of a slowly-biodegradable fraction into an easily-biodegradable fraction (R1); the breakdown of the easily-biodegradable fraction (R2), consuming O 2 , boosting microbial populations and releasing metabolites like CO 2 and H 2 O; the decay of microbes into a non-biodegradable fraction (R3); and the biomass moisture migration (R4). In the context of R1, two biomass degradation modes (Tremier and Haug) are considered, while R2 is characterized using four microbial growth kinetics models (square-root-type model, polynomial model, generalized linear model, Cardinal temperature model with inflection). These models can adapt to varying temperature and moisture levels, affecting microbial growth rates. By combining different R1 and R2 pathways, eight modelling pathways are established, and their parameters are derived using genetic algorithm and particle swarm optimization techniques, with the aim of minimizing disparities between experimental outcomes and model predictions. The model's performances are evaluated through several metrics such as CO 2 evolution rate, biomass dry matter loss, cumulative respiration, and overall prediction accuracy. The evaluation indicates that the Tremier model more accurately predicts biomass degradation across six types of biomass, and the Cardinal temperature model with inflection and square-root-type model offer superior predictions for microbial growth dynamics, especially for biomass types rich in cellulose and low in lignin content, e.g., wheat straw, corn stalk, rice straw and soybean hull. Our model dynamically refines the kinetic parameters for biomass decomposition and microbial metabolism based on changes in ambient temperature, humidity, and biomass moisture content over time. This feature enables real-time prediction of the decomposition state of biomass throughout extended storage periods. Furthermore, by incorporating an appropriate metabolic heat production model for the biomass, along with heat and mass transfer equations, our model can predict the internal temperature distribution within a biomass pile. This capability serves as a valuable tool for ensuring the safe storage of biomass, providing a robust means of managing the risks associated with biomass self-heating and self-ignition. [ABSTRACT FROM AUTHOR]

• Catalytic upgrading of bio-oil was conducted over metal oxide-modified Y zeolite. • The upgraded bio-oil by Fe/Y, Mg/Y and Zn/Y was rich in aromatics and phenols. • Ni/Y catalyst exhibited good selectivity to phenol and cresol. Pyrolysis as one of the most utilizations of biomass has aroused the increasing attention, however, the key is to upgrade biomass pyrolysis volatiles and enrich the high-valued chemicals in bio-oil. In this paper, different metal oxide-modified Y zeolites, including Fe/Y, Co/Y, Ni/Y, Mg/Y and Zn/Y, were prepared by wet impregnation and employed in catalytic upgrading of pyrolytic volatiles from rice straw (RS) and poplar sawdust (PS). Results showed that the modification by metal oxides led to the decrease of surface area and the changes in the acidity of zeolites. Higher yields of gas and water were obtained over metal oxide-modified zeolites at the expense of the bio-oil yields. More strong acid sites of the Ni/Y and Zn/Y catalysts promoted the generation of H 2. Fe/Y catalyst showed good selectivity to aromatics in bio-oil owing to high mesoporous volume and strong deoxidization capacity. The highest aromatic hydrocarbons content (63.0%) was obtained over Fe/Y in RS bio-oil. The formation of phenol and cresol was promoted with increasing the ratio of Lewis/Brönsted acid. Under the action of Ni/Y with the highest Lewis/Brönsted ratio, the phenol content in bio-oil from RS and PS pyrolysis was enhanced to 11.8% and 25.3%, respectively. The Fe/Y catalyst had good upgrading performance during three reaction-regeneration cycles. In addition, the possible reaction mechanism of biomass pyrolysis volatiles over metal oxide-modified Y zeolites was proposed. This work will provide a guide for the composition regulation of bio-oil from biomass pyrolysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • Established the relationship between molecular properties and electrode performance. • Biomass is used to realize the value of energy storage. • The carbon source unsaturation is obtained from the double bond equivalent diagram. Porous carbon materials have been considered a kind of promising materials for supercapacitors due to high specific surface area and excellent electronic conductivity. Soluble portions (SPs) acquired from thermal dissolution of carbon-based raw materials have been used as the carbon source for hierarchical porous carbons (HPC). In this work, mixtures of rice straw and coal at different mass ratios were selected as the raw materials for co-thermal dissolution to obtain SP X. The variation of soluble proportions and subsequent impacts on the electrochemical properties of HPC X were investigated. During thermal dissolution, the addition of rice straw increased the content of nitrogen-containing compounds in SP X. Therefore, the specific capacitance of HPC 1/4 is 355 F/g. The specific capacitance of activated carbon material without rice straw is only 299 F/g. The relationship between the molecular characteristics of carbon source and the performance of supercapacitors has been determined. In addition to oxygen-containing compounds, the presence of nitrogen-containing compounds can also lead to a higher electrochemical property for porous carbon materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • Quick measurement method of three components was established based on PT-TGA. • The method can be applicated with high heating rates up to 300 °C/min. • The time for three-component content measuring test can be as short as 3 min. • Maximum deviation of relative contents of three components was less than 3.32%. Cellulose, hemicellulose, and lignin are the major components of lignocellulosic biomass, and fast and accurate measurement of the three components' content is beneficial for the efficient application of biomass. However, the current chemical dissolution and titration method was tedious and time-consuming. In this study, a quick determination method of three components in biomass was developed for determining their contents based on a photo-thermal thermo-gravimetric analyzer (PT-TGA). Cellulose was modeled using a single F1 model, while hemicellulose and lignin were fitted with two consecutive processes according to their pyrolysis characteristic with F2 and F1 models. Using the kinetic parameters obtained from the fast pyrolysis of cellulose, hemicellulose and lignin on the PT-TGA, the contents of the three components in biomass samples were calculated by fitting the DTG curves with different peaks. Under the heating rate of 300 °C /min, the relative content deviation of the three components of rice straw was less than 2.00 % with the measurement time within 3 min. Furthermore, coconut shell and pine were used to verify that the maximum difference determined by the kinetic fitting method and the chemical method was only 3.32 %, demonstrating that the method could reliably and rapidly measure the contents of the three components in lignocellulosic biomass. This study provided a fast and effective method for determining the relative content of biomass components. [ABSTRACT FROM AUTHOR]

[Display omitted] • Rice straw (RS) was used to produce biohydrogen and nano-silica. • Organosolv-NaOH and sulfuric acid-NaOH treatments improve silica recovery and purity. • The influence of prepared nano-silica was evaluated on the dark fermentation of RS. • The pretreated rice straw with lower silica contents produces higher biohydrogen. • 63.8 mL H 2 /g rice straw was obtained in the presence of nano-silica particles. Rice straw stands as a highly sustainable agricultural residue enriched in silica and carbohydrates. This study delves into the potential of rice straw, focusing on the impact of green-synthesized nano-silica particles on biohydrogen fermentation using Enterobacter aerogenes. Rice straw was subjected to three different leading pretreatments, i.e., organsolv, sulfuric acid, and sodium hydroxide, to decimate the lignocellulosic structure. In addition to these, sodium hydroxide was employed as a secondary pretreatment for the organosolv- and sulfuric acid-pretreated straw. Three distinct nano-silica particles were extracted from the liquor of alkali pretreatments and examined using XRD, XRF, FE-SEM, and DLS analysis. The solid fractions of pretreatment were enzymatically hydrolyzed and subjected to dark fermentation, achieving the maximum biohydrogen yield of 156.9 ± 2.0 mL per g total solids (TS) from the organosolv-sodium hydroxide pretreated straw. Further improvement of biohydrogen yield to 178.3 ± 4.2 mL per g TS was obtained by adding 200 ppm of nano-silica particles isolated from one-step sodium hydroxide pretreatment. Analyzing the metabolic products exhibited that nano-silica particles modified the metabolic pathway, leading to an increase in acetic acid production and a decrease in ethanol production. It was concluded that nano-silica particles isolated from untreated and treated rice straws have the potential to boost biohydrogen generation. However, the degree of improvement was dependent on the composition and structure of the nanoparticles. [ABSTRACT FROM AUTHOR]

[Display omitted] • CSTR with GAC is an effective strategy for Clostridium spp. immobilization. • High butanol productivity of 2.07 g L−1 h−1 from RS hydrolysate. • GS plus two PV cycles at mild conditions concentrated butanol up to 291 g L−1. • Discontinuous downstream plus distillation reduced the energy use to 20.6 MJ kg−1. This study assessed the performance of two continuous stirred tank reactors (CSTRs) to immobilize Clostridium acetobutylicum DSM 792 and Clostridium beijerinckii DSM 6422 on granular activated carbon. Dilution rates (D) from 0.05 to 0.60 h−1 were tested using a sugar mixture to mimic rice straw hydrolysate. Immobilization was shown to be a highly effective technique for processing high flows without cell washout. Both CSTRs demonstrated significantly higher butanol productivity than their free-cell counterparts, achieving the remarkable value of 2.29 g L−1 h−1 with C. beijerinckii at D = 0.60 h−1. Rice straw hydrolysate was fed to the high-rate CSTR, reaching a butanol productivity of 2.07 g L−1 h−1 at D = 0.30 h−1. A novel downstream configuration of ex situ gas stripping followed by two pervaporation cycles operated under rough vacuum was explored in discontinuous mode, that reduced the energy demand by 63 % of conventional distillation methods. This configuration holds great promise for the advance of the lignocellulosic biorefinery process. [ABSTRACT FROM AUTHOR]

• Inocula improved methane production in a straw anaerobic fermentation system. • Inoculation increased the abundance and diversity of bacterial community and archaeal community in the early and middle stages and the early stage of fermentation. • Inoculation altered the metabolic pathway of archaea from low-efficiency acetotrophic methanogenesis to high-efficiency hydrogenotrophic methanogenesis in the early stage.. Field experiments have shown that the mixed anaerobic digestion of straw with livestock and poultry manure can improve the efficiency of biogas production. We hypothesize that inoculation with livestock and poultry manure increase the efficiency of methane production by improving the diversity and structure of microbial community in the field anaerobic digestion system. In this study, an experimental system was established to simulate the microbial community of the mixed anaerobic digestion system in the field. The methane production and taxonomic composition of bacterial and archaeal communities in the rice straw anaerobic digestion systems were determined. We aim to reveal the effects of the inocula on the diversity and composition of bacterial and archaeal communities and the mechanism underlying the impact on biogas production in the field. The following results were obtained. (1) Inoculation significantly improved the efficiency of methane production in anaerobic digestion, and the best performance was achieved with treatment A (cleared biogas slurry), which obtained methane production that were 39.59 %, 106.85 %, and 123.00 % higher than in treatment B (pig manure extract), C (cleared biogas slurry + pig manure extract), and the control, respectively. (2) The inocula increased the abundance and diversity of bacterial communities in the early and middle stages and archaeal communities in the early stage. (3) The inocula also had a significant impact on bacterial and archaeal community composition in the early and middle stages. The inocula increased the relative abundance of Aquamicrobium_A , Proteiniphilum , and Cryptobacteroides but reduced the relative abundance of Macellibacteroides , Acinetobacter , and Phocaeicola. The dominant genus of archaeal community was altered from Methanosarcina to Methanocorpusculum. (4) It is concluded that inoculation significantly increase methane production as the inocula improve the abundance and diversity of bacteria and archaea of anaerobic digestion systems in the early and middle stages of digestion, as well as improve the structure and metabolic pathway of archaeal communities. [ABSTRACT FROM AUTHOR]

[Display omitted] • Digested manure yielded 7.07-fold more biogas and 401.33-fold more methane from rice straw. • The AD system containing raw manure and rice straw collapsed and produced negligible methane. • The digested manure showed better buffering capacity compared to raw manure. • 116 common microbes in digested manure at the beginning and raw manure at the end of digestion. • Hydrogenotrophic methanogens were more abundant compared to acetoclastic methanogens. The application of anaerobic digestion (AD) for the management of rice straw (RS) provides a way to generate bioenergy to tackle greenhouse gas emissions caused by conventional burning and tilling of straw back into the fields. The existing research often neglects inoculum selectivity and microbial community roles in AD. This study demonstrates the superiority of the microbial community from digested manure (ADS) over raw manure (CD) in producing biogas from rice straw. Notably, the microbial community of digested manure progressively resembled that of raw cow dung after 45 days of anaerobic digestion showing 116 common bacterial genera in comparison to just 9 at the beginning of the experiment. The dominant bacterial genus observed was Clostridiales , with its abundance rising from 9.86% to 38.40% in ADS and declining from 38.16% to 7.53% in CD from day 0 and day 45. This was succeeded by a rise in Prevotella and a reduction in Pseudomonas as the days advanced. Methanobrevibacter was the dominant genus of hydrogenotrophic archaea whose abundance increased from 8.20% to 64.25% in ADS and decreased from 61.41% to 8.98% in CD. Reactors inoculated with ADS outperformed those inoculated with raw CD by producing 7.07 times higher biogas. Additionally, the study highlights the influence of microbial dynamics on volatile fatty acid accumulation, and buffering capacity of the AD system. The significance of this research lies in enhanced microbial activity and digestion rate, reduced start-up time, and adaptation to feedstock resulting in higher biogas production. [ABSTRACT FROM AUTHOR]

[Display omitted] • The g-C3N4 is synthesized via thermal polycondensation using melamine as the precursor for pre-treating rice straw. • The photocatalytic oxidation effectively removes the silica (72%) content present in the rice straw. • The methane yield is increased to 61% after a pretreatment duration of 6 h. The growing importance of biofuels as a sustainable alternative to fossil fuels necessitates exploring effective utilization of abundant resources like rice straw, which currently contributes to environmental pollution through inefficient burning. This research focuses on harnessing the potential of g-C3N4 photocatalytic pretreatment to enhance rice straw's structure and improve biogas production. Detailed analysis employing FESEM, EDX, XRD, and FTIR techniques revealed substantial structural changes. Silica content decreased from 22.84 % in untreated rice straw to 18.05 % and 6.39 % after 3 and 6 h of treatment, respectively, while carbon content increased from 28.05 % to 38.54 % and 48.02 % during the same treatment durations. Significantly, methane production experienced a remarkable increase from 198.21 to 512.14 mL/g VS after 6 h of treatment, and the cellulose concentration in the biomass exhibited a substantial rise of 39 % compared to untreated samples. These findings underscore the efficacy of g-C3N4 photocatalysis in facilitating rice straw hydrolysis for biogas production, showcasing its potential to transform agricultural waste into sustainable biofuels. [ABSTRACT FROM AUTHOR]

• Ash fusibility and flow velocity decreased with increased residual carbon. • Three percent residual carbon obviously affected the fusibility and flow velocity of ash. • A carbothermic reaction occurred in rice straw ash containing residual carbon. • The residual carbon in ash reduced the migration of SiO 2 to low melting silicate. Residual carbon is a non-negligible component in biomass gasification slag and is seen as a factor related to the flowability of slag. One purpose of this study was to explore the relationship between residual carbon and rice straw ash fusibility via an ash fusibility temperatures (AFT) test in an argon (Ar) atmosphere. A visual measurement method for slag flow velocity was also established to further reveal slag flow properties. Furthermore, to illustrate the reaction mechanism of residual carbon with mineral components in ash, the surface morphology and chemical components of ash prepared at high temperatures were examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD), and the effects of residual carbon on rice straw ash fusibility characteristics were quantitatively calculated by thermodynamic equilibrium calculations. The experimental results showed that the increase in residual carbon mass fraction in ash increased ash fusibility temperatures and reduced slag flow velocity. The characterization and thermodynamic calculations indicated that in the ash fusion process, the rod-like structure containing carbon in ash disappeared, and the surface became compact due to the carbothermic reaction with SiO 2 with continuously rising temperatures. Then, the unreacted residual carbon and SiC could be completely covered by molten slag due to the further increase in the liquid phase caused by the melting CaMgSiO 4 and CaMgSi 2 O 6. The residual carbon in ash inhibited the formation of K 2 Si 4 O 9 , which further resulted in reduction of SiO 2 migration to low melting silicate. [ABSTRACT FROM AUTHOR]

• Three types of solution with different severities were used to wash rice straw. • One sharp peak was in DTG curves for Raw-RS, but two peaks for HCl-RS and APBO-RS. • Evolution of evolved gases (H 2 O, CH 4 , CO, CO 2 , and C O stretching) was analyzed. • APBO pretreatment showed the highest activation energy for rice straw pyrolysis. • The relative content of levoglucosan was increased because of the removing of AAEMs. Washing pretreatment is a promising method for upgrading biomass by removing alkali metal and alkaline earth metals (AAEMs). In this study, three types of solution with different pretreatment severities (i.e., water (H 2 O), dilute hydrochloric acid (HCl) solution, and aqueous phase bio-oil (APBO)) were used to study the effects of the washing pretreatment on the pyrolysis behaviors and kinetics of rice straw. The pyrolysis experiments of raw and pretreated rice straw (Raw-RS, H 2 O-RS, HCl-RS, and APBO-RS) were carried out using TG-FTIR and Py-GC/MS. Results show that among the three types of washing pretreatment methods, the APBO washing pretreatment has the highest removal efficiency of AAEMs: 99.7% of K, 91.7% of Na, 96.6% of Mg, and 95.2% of Ca. According to TG-FTIR results, only one sharp mass loss peak was present in the DTG curves of Raw-RS and H 2 O-RS, whereas two mass loss peaks (one sharp peak and one shoulder peak) were observed in HCl-RS and APBO-RS. The evolution pattern of the volatile compounds (H 2 O, CH 4 , CO, CO 2 , and C O stretching) was thoroughly investigated, and the absorbance intensity of these components increased with the washing pretreatment of APBO and HCl. The APBO washing pretreatment had the highest activation energy in the conversion rate of 0.2–0.75, followed by HCl and H 2 O washing pretreatment. According to the Py-GC/MS results, the washing pretreatment reduced the relative contents of acids, ketones, furans, and phenols in bio-oil, whereas removing of AAEMs increased the relative contents of anhydrosugars (mainly levoglucosan). Among the three types of washing pretreatments, the APBO washing pretreatment had the most remarkable influence on the property of bio-oil, and this indicates that the APBO washing pretreatment is a promising method for upgrading biomass and its pyrolytic product. [ABSTRACT FROM AUTHOR]

Abstract To investigate the conversion of nitrogen bound in biomass fuel (abbreviated to fuel-N) during biomass pyrolysis, wheat straw (WS), rice straw (RS), spent coffee grounds (SCG) and palm kernel cake (PKC) were isothermally pyrolyzed in a horizontal tube reactor at the temperature range of 500–900 °C. The concentrations of light gaseous nitrogen containing species (gas-N) were measured online by a Fourier transform infrared (FTIR) spectroscopy gas analyzer, and the corresponding conversion rates were calculated. Results indicated that the conversion of fuel-N to gas-N as well as the evolution of N-functionalities in the portion of fuel-N that maintained in the char (char-N) were consistent regardless of the original N-functionalities in biomass samples. The conversion of fuel-N was found to be highly reliant on the temperature and fuel-N content. 17–47% of the fuel-N was finally retained in the char during pyrolysis. Therefore, the evolution of the N-functionalities from fuel-N to char-N was analyzed by X-ray photoelectron spectroscopy (XPS). Amide-N (N-A) was confirmed to be the dominant N-functionality in the raw biomass samples, and a small amount of pyrrolic-N (N-5), pyridinic-N (N-6) and quaternary-N (N-Q) were also identified. After pyrolysis, N-A was completely vanished in the char. However, only a very small fraction of N-A was decomposed into NH 3 while most of it was preferentially converted to other gas-N (HCN, HNCO and NO) and N-5/N-6. For N-5/N-6, most of them preferred to retain in the char. As the temperature increased, a small amount of N-5/N-6 was converted to more stable N-Q and N-oxides (N-X) structures. Contrary to expected, N-A was also the main contributor to the formation of HCN, while the contribution from N-5/N-6 was less important. Finally, the conversion mechanism of fuel-N was concluded. [ABSTRACT FROM AUTHOR]

Highlights • Impact of biomass particle size on glucan conversion was studied. • Maximum glucan conversion was obtained for 10 mm particle size. • Increasing the enzyme dosages results in 14% higher glucan conversion. • In the current set of parameters 10 mm particle size was found to be optimum. • Lower LOI and higher S/G ratio leading to higher overall sugar recovery. Abstract Rice straw has a great potential for ethanol production due to its richness in polysaccharides and abundant availability, however, for efficient utilization of these polysaccharides, size reduction is a prerequisite step. Therefore, biomass particle size plays a vital role for cellulosic ethanol commercialization. In this study, the effects of rice straw particle size on dilute acid pretreatment efficiency and enzymatic hydrolysis are investigated. Different sizes; 5, 10 and 20 mm were subjected to dilute acid pretreatment in a continuous pilot scale system with a horizontal screw feeder reactor followed by enzymatic hydrolysis at varying solids (10 and 15%) and enzyme dosages (5 and 10 FPU/g of pretreated residue). The glucan hydrolysis for 5, 10 and 20 mm are 65.6, 80.0 and 60.0% using 5 FPU and 79.5, 93.4 and 72.8% using 10 FPU/g pretreated residue respectively at 10% loading, whereas, at 15% it is significantly lower in respective experiment. Overall sugar recovery with 10 mm is 63.8 and 72.9% with 5 and 10 FPU respectively. RS with 10 mm biomass particle size at both solid loadings and enzyme dosages resulted in much higher enzymatic hydrolysis than others and in turn the overall sugar recovery and this was found to be due to the variation in the degradation products and pseudolignin contents in the pretreated biomass. The insight into the structural intricacies of biomass after pretreatment are studied using FT-IR and SEM revealing significant changes in biomass properties responsible for improved sugar recovery. [ABSTRACT FROM AUTHOR]

Abstract Char-N is the part of the nitrogen bound in the fuel (fuel-N) that remained in the char matrix during biomass pyrolysis, which is the initial of combustion. Therefore, char-N is responsible for the emission of NOx and N 2 O during combustion. In this study, biomass char was produced by pyrolysis of rice straw (RS) and pine sawdust (PS) under Ar atmosphere at 500–900 °C. The N-functionalities and the surface area of the chars were characterized by X-ray photoelectron spectroscopy and Brunauer–Emmett–Teller analysis, respectively. Then, combustion experiments of biomass char were conducted in Ar/O 2 to explore the conversion of char-N and the proportion of fuel-N released as char-NO (char-NO/fuel-N). Besides, biomass char was additionally combusted in N 2 /O 2 as comparison. Results showed that NO was the dominant N-containing product and little N 2 O was found. NO 2 was not observed. Both NO and N 2 O were formed by direct oxidation of char-N. No obvious difference was observed during char combustion in N 2 /O 2 and Ar/O 2 environments. With the increase in temperature, the NO concentration generally increased whereas the reverse was observed for char-NO/fuel-N. The concentration of NO clearly increased as the O 2 percentage increased, while NO/char-N and char-NO/fuel-N were not obviously affected. The heating time showed negligible influence on char-N conversion. The increase in the char mass led to dramatically decrease in the conversion of char-N and char-NO/fuel-N. However, no clear correlation could be revealed between the char-N conversion and the evolution of N-functionalities as well the surface area of the char. [ABSTRACT FROM AUTHOR]

Highlights • Sequential leaching and wet torrefaction were carried out to improve the fuel properties. • Ash content in EFB was removed effectively by the leaching process. • Most potassium and chloride were removed by leaching and wet torrefaction. • The hydrophobicity of the biomass was enhanced by sequential leaching and wet torrefaction. Abstract In this study, sequential leaching (60 °C, 5 min) and wet torrefaction (200 °C, 5 min) of biomass were carried out to improve the fuel properties of waste biomass, made up of empty fruit bunches (EFB), rice straws (RS), or sugarcane bagasses (SB). Most of the hemicellulose was removed during wet torrefaction. The ash removal efficiency by sequential leaching and wet torrefaction differed depending on the biomass. After leaching and wet torrefaction, the ash removal efficiency of the EFB was the highest (67.99%). Most of the potassium and chloride in the biomass were removed. In particular, the removal efficiencies for the EFB were the highest (98.62% and 99.27%, respectively). The heating values increased by 4.42% in the EFB, 4.68% in the RS, and 5.30% in the SB. Pellet production was successfully carried out with the leaching and wet-torrefied biomass (EFB). The hydrophobicity of the pellets was considerably higher than that of the raw material. [ABSTRACT FROM AUTHOR]

[Display omitted] • Kitchen food waste was co-pyrolyzed with rice straw for biochar production. • Uncatalyzed feedstocks produced biochar having poor fuel properties. • Blending and addition of catalysts improved the gross calorific value of biochar. • Co-pyrolysis under ZnCl 2 is suitable for upgrading fuel properties of biochar. In this research, microwave co-pyrolysis of kitchen food waste and rice straw under no susceptor, biochar susceptor, and ZnCl 2 susceptor was undertaken to investigate the synergistic effects on biochar properties for energy application. The results showed that co-pyrolysis and the addition of susceptors significantly positively affected the thermochemical, fuel, thermal, and surface properties of biochar. Regardless of the susceptor conditions, blending kitchen food waste with rice straw effectively decreased the biochar yield (up to 2.14% and 6% for biochar and ZnCl 2 susceptors, respectively) and abundance of –OH functional groups, but improved the chars' thermal stability and surface area. Biochar produced at a ratio of 1:1 under ZnCl 2 exhibited acceptably low ash content coupled with high higher heating value (20.550 MJ/kg), high energy yield (55.944%), and high fuel ratio (≤5.267) thereby demonstrating excellent fuel properties. These findings highlight the exceptional potential of co-pyrolytic biochar as a sustainable and eco-friendly energy source. [ABSTRACT FROM AUTHOR]

• First-time demonstration of aerobic granulation technology for bioethanol production. • Yeast aerobic granules were developed in 4–6 days. • Activated charcoal, silica, and concrete aggregate column-based detoxification of rice straw hydrolysate. • Continuous bioethanol production was achieved for more than 60 days. For the first time application of aerobic granulation technology has been demonstrated for bioethanol production. A reactor was fabricated for ethanol production from rice straw hydrolysate (RSH) using Saccharomyces cerevisiae aerobic granules. The yeast granules were developed within 4–6 days by alternate aerobic mixing phase and settling phase without airflow of 8 h and 4 h, respectively. These yeast granules were found to produce ethanol (34.42 g/L) from pure glucose (80 g/L). A column filter was designed using activated charcoal, silica, cotton, and concrete aggregate to eliminate toxic impurities from RSH. Compared to unfiltered RSH, the filtered one was found to be more effective in ethanol production. A maximum of 16.18 g/L ethanol was produced from filtered RSH containing 10 g/L reducing sugar supplemented with pure glucose (40 g/L). It was possible to continuously run the process for more than 60 days. This study for the first time demonstrates continuous bioethanol production for an extended period by repeated use of yeast in the form of novel aerobic granules. This new concept has the potential to improve bioethanol production efficiencies of existing biorefineries. [ABSTRACT FROM AUTHOR]

Graphical abstract Schematic representation of optimization of process variable for co-digestion of rice straw and hydrilla verticillata. Highlights • Anaerobic co-digestion of rice straw with hydrilla verticillata enhanced the methane yield. • CCD-RSM design was used to optimize the methane yield. • Maximum methane yield was obtained under interactive effect of C/N ration and F/M ratio. • The optimum condition for maximum methane yield was documented. Abstract Anaerobic co-digestion is a realistic approach to concurrently manage agriculture residue and harness renewable energy. To achieve the anaerobic degradation requirements and to recompense the nitrogen deficiency of rice straw, it should be digested with another nitrogen-rich co-substrate to advance its characteristics. This study exhibits the necessity of co-digestion to improve physicochemical and biochemical progression compared to mono-digestion. The individual effect of carbon/nitrogen (C/N) ratio, food/microorganisms (F/M) ratio and pH, in addition to their interaction effects on methane yield (mL CH 4 /g-VS added) were explored in this study. A central composite design – response surface methodology was used for defining the experimental design for anaerobic co-digestion of rice straw and hydrilla verticillata. Results of this study showed significant interaction of C/N ratio and F/M ratio, and individual response parameters on methane yields. The optimum condition for anaerobic co-digestion (C/N ratio 29.7, F/M ratio 2.15 and pH 7.34) showed methane yield of 287.6 mL CH 4 /g-VS added , 1.84 fold (156.32 mL CH 4 /g-VS added) higher than mono-digestion (control). Model validation proved the high adequacy of the model and methane yield is good output response variable for co-digestion study and it is necessary to optimize the transient variation in C/N ratio, F/M ratio and pH. [ABSTRACT FROM AUTHOR]

The ash fusion process of Jincheng anthracite ash, rice straw ash and coal-biomass ashes with different rice straw ash addition ratios during co-gasification under CO 2 atmosphere was elucidated by the ash fusion test, chemical analyses, optical heating stage microscopy (OHSM), X-ray diffraction and scanning electron microscopy equipped with energy-dispersive X-ray analyzer. Results showed that the initial sintering and initial melting temperatures of coal-biomass ashes observed by OHSM decreased with the addition of rice straw ash. The deformation temperatures determined by the ash fusion test were close to the initial melting temperatures. The biomass ash addition to coal ash introduced excessive amounts of alkaline compounds in the ash mixtures that led to lower initial temperatures of liquid phase formation. The ash fusion behavior of coal-biomass ashes with a rice straw ash addition ≤3 wt% was similar to that of coal ash and fits to the “softening-melting” ash fusion mechanism. In contrast, the ash fusion behavior of coal-biomass ashes with a greater addition of rice straw ash (>3 wt%) experienced dramatic changes at lower temperature and fits to the ‘‘melting-dissolution’’ ash fusion mechanism. [ABSTRACT FROM AUTHOR]

[Display omitted] • The effect of residual carbon recovered from CGFS on rice straw HTC was explored. • The presence of residual carbon can decontaminate hydrothermal wastewater. • Residual carbon can induce small organic molecules to condense into hydrochar. • The abundant pores of residual carbon can adsorb alkali metals in the aqueous phase. • The combustion reactivity of residual carbon is improved after HTC with rice straw. The large-scale resource utilization of coal gasification fine slag (CGFS) and the decontamination of wastewater through the hydrothermal carbonization (HTC) process of biomass are crucial for the production of clean fuels. In this study, the residual carbon in CGFS was recovered by froth flotation, and the HTC of rice straw was carried out with different addition amounts of residual carbon and hydrothermal temperatures. The physicochemical structure and fuel properties of hydrochar as well as water quality indicators of hydrothermal wastewater were carefully explored. The results showed that the combustion reactivity of residual carbon was significantly improved, implying an obvious synergistic effect after inducing HTC of rice straw. In addition, the wastewater produced by rice straw HTC was dark brown and contained high concentration of complex organic substances. The addition of residual carbon significantly improved the water quality of hydrothermal wastewater by removing organic matter. The abundant pore structure of the residual carbon can adsorb the organic molecules in the aqueous phase and induce their polymerization and conversion into hydrochar, thereby reducing the concentration of organic compounds in the wastewater and improving the water quality. At the same time, it can also adsorb potassium metal ion dissolved in the aqueous phase by rice straw. Hydrochar formed on the surface of residual carbon has lower aromatic condensation degree and more carbon defects, which can provide more reaction sites. In addition, the alkali metal adsorbed on residual carbon has a catalytic effect. All the above factors contribute to the synergistic effect of combustion reaction. [ABSTRACT FROM AUTHOR]

[Display omitted] • (Co-)pyrolysis prcesses are modeled and optimized using SuperPro designer software. • Lowest capital cost is estimated for rice straw plant and highest of co-feed plant. • Highest OPEX for tire plant (M $77.185) due to hgihest procurement and utility cost. • Co-feed plant is most viable due to highest revenue generation from oil and power. • Selling price of oil and feedstock procurement cost are most sensitive parameters. In this study, three pyrolysis and co-pyrolysis plants processing rice straw (RS) and scrap rubber tire (SRT) to produce oil and power (i.e., electricity) at 30 t/hr capacity are simulated using SuperPro Designer software. The objective of the study is to comparatively evaluate the techno-economic performance of hypothetical (co-)pyrolysis plants at commercial scale. The RS production is estimated in 36 districts of Punjab, Pakistan through GIS mapping and the location and capacity of the plants are selected accordingly. The RS plant has the lowest capital and annual operating costs of $53.70 million and $43.70 million, respectively however, it is not economically feasible under current conditions due to its low quantity and quality of the produced oil. The base cases of SRT and co-feed (RS and SRT) plants are found to be viable with capital costs of $66.90 million and $68.30 million, and annual operating costs of $77.20 million and $70.30 million respectively. The co-pyrolysis plant produces the highest oil (main product) yield of 74 kilotons annually and power of 4801 KWe with the lowest unit production cost of $950/tonne. Consequently, the co-pyrolysis plant offers the highest economic performance with $35.55 million of net present value (NPV) estimated at a discount rate of 15% over 20 years of plant life. The payback period (PBT), internal rate of return (IRR) and gross margin (GM) are 5.08 years, 34.67% and 21.35% respectively. Sensitivity analysis suggests that the NPV is sensitive to the oil selling price, feedstock cost, and capital investment for all plants. Moreover, economy of scale analysis quantified the effects of different processing capacities on the economic metrics such as NPV, PBT, capital cost, and operating cost. [ABSTRACT FROM AUTHOR]

The improvement of organonitrogen compounds (ONCs) in methanol-soluble portions (MSPs) obtained from supercritical methanolysis of raw and pretreated rice straw (RS) with Trichoderma sp. AH was investigated. According to detailed analysis with positive-ion ESI FT-ICR MS and GC/MS, the molecular masses (MMs) of ONCs in MSPs of raw and pretreated RS range from 100 to 500 u and dominate from 300 to 450 u . The relative abundance of ONCs with MMs from 300 to 350 u in MSP of pretreated RS is higher than those in MSP of raw RS. Most of detected ONCs in MSPs of raw and pretreated RS are N 2 O n (n = 1–9) species with double bond equivalent values of 2–25 and carbon atom numbers of 4–35. The most abundant ONCs in MSP of pretreated RS are N 2 O 4 , while those in MSP of raw RS are N 2 O 5 . These results facilitate understanding the effect of pretreatment with Trichoderma sp. AH on the conversion and specificity of ONCs in methanolysis of RS and the application of MSP on production of transportation fuel. [ABSTRACT FROM AUTHOR]

To study the transformation of organic structure and mineral matter in coal-biomass mixtures during co-gasification, the anthracite and rice straw addition with different ratios were isothermally gasified at 1100 °C under CO 2 atmosphere in a fixed bed reactor. The phase-mineral composition, morphology and organic structure of solid residues produced at different gasification time were analyzed by X-ray diffraction, scanning electron microscopy coupled with energy dispersive spectrometer, Raman spectroscopy and other methods. Results revealed that the organic structure was changed in char as it became less ordered with the addition of biomass. The bulk concentrations of K and Na and their bearing minerals and phases in char increased with the addition of biomass during gasification process. The transformation of mineral matter played a significant role in promoting the coal gasification. [ABSTRACT FROM AUTHOR]

• Dynamic K migration and transformation characteristics during biochar combustion were studied. • Effect of O 2 concentrations on K migration and transformation path was investigated. • Correlation between K migration/transformation and char combustion reactivity was discussed. For agricultural biomass combustion, K migration and transformation is a key factor affecting boiler operation and reaction characteristics. In this study, dynamic K migration and transformation characteristics during rice straw char combustion process under different O 2 concentrations were studied using chemical fractionation analysis (CFA), X-ray diffraction (XRD) and scanning electron microscopy coupled with energy dispersive X-ray (SEM-EDX). Furthermore, the correlation between K migration/transformation and char combustion reactivity was discussed. The results showed that most of K in rice straw char was H 2 O-soluble K. And the main forms of H 2 O-soluble K and insoluble K are KCl and KAlSi 3 O 8 , respectively. As reaction proceeded, the contents of H 2 O-soluble K and insoluble K decreased but those of NH 4 Ac-soluble K and HCl-soluble K increased. Most of the released K is H 2 O-soluble K. H 2 O-soluble K would be transformed into NH 4 Ac-soluble K and HCl-soluble K, and some insoluble K would be transformed into H 2 O-soluble K. The increase of O 2 concentration would stimulate the transformation of H 2 O-soluble K into NH 4 Ac-soluble K, HCl-soluble K and released K. However, the reaction to form K-aluminosilicate was hardly found during the combustion process at 400 ℃. Ultimately, it is found that H 2 O-soluble K is the key occurrence form K affecting the combustion characteristics of rice straw char. [ABSTRACT FROM AUTHOR]

[Display omitted] • Biochar-activated peroxydisulfate system is used for the first time to oxidize NO from flue gas. • NO is mainly removed by the produced free radicals such as ·OH and SO 4 −·. • ·OH is identified as the first important free radical for oxidizing NO. • SO 4 −· is determined to be the second important free radical for oxidizing NO. • The maximum NO removal efficiency is up to 95.2%. Biochar-activated peroxydisulfate oxidation technology has received more and more attention due to its low metal ion leakage rate and low solid waste post-treatment requirement. In this paper, rice straw biochar-activated peroxydisulfate oxidation technology is used for the first time to oxidize nitric oxide (NO) from flue gas through inducing free radicals. The mechanism of NO oxidation removal is mainly explored. The main factors affecting NO removal, removal products and free radicals are also systematically studied. Results show that the main product of NO oxidation removal is NO 3 − and no extra by-product is formed. · OH is identified as the first important free radical for oxidizing NO, while SO 4 − · is determined to be the second important free radical for oxidizing NO. Peroxydisulfate oxidation only plays a minor supplementary role in NO removal. Increasing rice straw biochar mass concentration and operation temperature promote NO removal. Increasing NO concentration and solution pH value are found to be harmful to NO removal. Increasing peroxydisulfate concentration first increases and then decreases NO removal efficiency. Under optimized process parameters, the maximum NO removal efficiency reaches 95.2%. [ABSTRACT FROM AUTHOR]

[Display omitted] • Six PILs were studied in rice straw pretreatment followed by enzymatic hydrolysis. • Acetate PILs were best candidates than hydrogen sulfate PILs. • [MEOA][OAc] showed the highest delignification and enzymatic hydrolysis yield. • Sugar and butanol production were maintained up to five reuses of [MEOA][OAc] • The use of [MEOA][OAc] could be a good pathway to unseat conventional pretreatments. Biomass pretreatment with protic ionic liquids (PILs) has been proved as an economically attractive method to enhance saccharification yield. This work evaluated the use of six PILs -based on acetate and hydrogen sulfate anions - using water as cosolvent for processing a high solid loading of rice straw (RS). Among the investigated PILs, the most promising results were obtained by 2-hydroxyethylammonium acetate [MEOA][OAc] containing 20 %w/w water, achieving 87.3 % of glucose and 68.6 % of xylose yield, respectively, and 98.3 % of delignification at 150 °C for 2 h with 15 %w/w solid loading. Five recovery and reuse cycles were successfully performed with [MEOA][OAc], obtaining a delignification degree of 69.5 % after the fifth reuse. Process viability was evaluated by enzymatic hydrolysis followed by acetone-butanol-ethanol (ABE) fermentation using Clostridium beijerinckii. Similar saccharification yields (89.9 ± 6.8 % glucose and 71.5 ± 4.7 % xylose) and butanol production (7.3 ± 0.1 g/L, 81.7 ± 1.7 g butanol per kg of RS) were achieved for fresh and recycled [MEOA][OAc], demonstrating the feasibility of PIL reuse. This study showed the potential of [MEOA][OAc] as a cost-effective pretreatment agent for rice straw valorization into an advanced biofuel such as butanol. [ABSTRACT FROM AUTHOR]

Pyrolysis experiments in a fixed-bed reactor at 800–1200 °C were carried out to compare the release and transformation behavior of Cl between raw and torrefied rice straw. The impact of torrefaction pretreatment on total release of Cl during rice straw high temperature pyrolysis has also been assessed. The influence factors, including volatile matter, particle structure, surface elements enrichment and occurrence forms of Cl, which are different between raw and torrefied rice straw, have been studied. The results show that Cl release ratios of torrefied rice straw at 250 and 300 °C are lower than that of raw rice straw during pyrolysis at 800–1200 °C. At 900–1200 °C, release ratio of Cl of torrefied rice straw decreases with the torrefaction severity. Torrefaction pretreatment at 250 and 300 °C inhibits the total release of Cl during rice straw pyrolysis at 1000–1200 °C. Enrichment of Cl on surface for torrefied rice straw accelerates the release of Cl. The removed volatiles during torrefaction would reduce the release of Cl during pyrolysis, and generated organochlorine (or C Cl) during torrefaction has the same inhibiting effect on the release of Cl. Surface morphology and specific surface area of pyrolysis char are different between raw and torrefied rice straw. Less specific surface area for pyrolysis char of torrefied rice straw at 250 and 300 °C would restrict the release of Cl. [ABSTRACT FROM AUTHOR]

The processes of pyrolysis and combustion of rice straw will be carried out in a spouted bed reactor. Both thermo-chemical processes were simulated in the first stage by multi-rate linear non-isothermal thermogravimetric (TGA) experiments using Ar and O 2 as carrier gas respectively. The results obtained from the TGA measurements, the kinetic methodology based on the combination of the iso-conversional methods Friedman, Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose, Vyazovkin and the use of Master Plots assessed by Perez-Maqueda criterion have permitted to describe mathematically both thermo-chemical reactions. Lower operational temperatures and higher kinetic parameters ( Ea , n , A ) were required to carry out combustion reactions respect to those for pyrolysis. These results will be the initial parameters that will define both thermo-chemical processes in a spouted bed reactor. [ABSTRACT FROM AUTHOR]

In this work, Trichoderma reesei Aq-5b and Trichoderma viride NSW-XM, capable of excreting lignin-degrading enzymes and cellulase were used to create a mixed culture system to hydrolyze rice straw in situ . The results showed that Aq-5b and NSW-XM were able to co-grow and produce complementary lignin degrading enzymes, namely laccase and lignin peroxidase. The two microorganisms were able to produce 22.74 g/L of reducing sugar in the optimal condition. For fermentation of the hydrolysates produced, Saccharomyces cerevisiae and Candida tropicalis NSW-NW were co-immobilized in polymer beads composed of sodium alginate, polyvinyl alcohol, and silicon dioxide (SA–PVA–SiO 2 ). The beads remained intact after 4 cycles of use and provided satisfactory protection for the yeasts and a suitable microenvironment for ethanol fermentation, greatly improved the efficiency of ethanol production, shortened the fermentation cycle and achieved yeasts recycling for continuous or batch-fed fermentation. The productivity of ethanol reached up to 2.17 g/(L h). [ABSTRACT FROM AUTHOR]

This study investigates the release and migration of potassium (K) and chlorine (Cl) in micro-spatial distribution during rice straw pyrolysis in a lab-scale reactor at temperatures from 300 °C to 900 °C. The K and Cl enrichment region and the morphology of K- and Cl-rich particles in rice straw and char obtained after pyrolysis was clearly revealed for the first time in this field of research. Scanning Electron Microscope/Energy-Dispersive Spectrometry (SEM/EDS) was used to analyze the morphology and distribution of inorganic matters in raw rice straw and water-washed rice straw, as well as the char obtained from raw rice straw pyrolysis, both upon the epidermis (outside surface) and the ground tissue (internal surface). X-ray Diffraction (XRD) was used to analyze the inorganic matters in the obtained char. The particles dispersedly distributed on the cell walls in the ground tissue were proven to be inorganic salt, rich in K and Cl. The ground tissue rather than the epidermis is the main part that decomposes and loses weight during pyrolysis. K and Cl diffuse from the ground tissue to the epidermis and they might be partly restricted to the epidermis during rice straw pyrolysis. The release of K and Cl is determined by both the mobility of K and Cl and the resistance along the diffusion way inside rice straw. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cu+-cysteine/Cu2+-cysteine complex is formed by adding Cu2+ into cysteine-rich medium. • Cu+-cysteine/Cu2+-cysteine complex enhances the activity of ctf AB. • Cu+-cysteine/Cu2+-cysteine complex catalyze cysteine oxidation and NADH regeneration. • The upgraded ctf AB and NADH/NAD+ improve butanol production. Butanol production from rice straw via Acetone-Butanol-Ethanol (ABE) fermentation has been considered a sustainable and cost-effective approach to cope with energy crisis and environmental issues. However, a number of factors, particularly low butanol production and energy-intensive separation, impede its industrial application. In this study, Cu2+, Zn2+, Fe2+, and Ni2+ were individually induced into the ABE fermentation system of Clostridium beijerinckii NCIMB 8052 with butyric acid and sugars both from rice straw as co-substrates to increase the specific butanol yield. The results demonstrated that the additional 0.20 g/L Cu2+ (i.e. 1.25 mmol/L) significantly increased SBY and butanol/acetone to 0.194 ± 0.006 g/g rice straw and 3.90 ± 0.21, respectively, compared to those of 0.126 ± 0.004 g/g rice straw and 2.61 ± 0.17 in control system. The improved butanol production was attributed to the formation of Cu2+-cysteine/Cu+-cysteine complex, which enhanced the adsorption of butyrate from rice straw by upgrading the activity of key enzyme (ctf AB) and NADH/NAD+. The study provides a reinforcement strategy for efficient lignocellulosic butanol production. [ABSTRACT FROM AUTHOR]

A parametric analysis of two gasification processes (i.e., steam–air and steam–CO 2 ) of rice straw feedstock is performed using a thermodynamic model-based approach developed in Aspen plus. The possibility of one step H 2 /CO ratio adjustment in a gasifier at thermal self-sufficient condition is observed. The effects of changes in the ratio of gasifying agent on the syngas yield, H 2 /CO ratio, total energy consumption and cold gas efficiency of the system at different gasifying temperatures in the range of 500–1000 °C are investigated. The syngas yield of both gasification processes significantly increases at low temperature until it reaches a maximum value and is stable at temperatures higher than 700 °C. However, the steam–CO 2 system offers higher syngas productivity and a lower H 2 /CO ratio. The total energy consumption of the system is also investigated, and the steam–air system consumes less energy and the thermal self-sufficient conditions are revealed, whereas the steam–CO 2 system shows the inverse effect. Based on the thermal self-sufficient condition for syngas production, the operating conditions offering the highest syngas yield of 42% of with Fischer–Tropsch specification can be obtained at a gasifying temperature of 700 °C and steam- and air-to-biomass ratios of 0.57 and 1.17, respectively. At these conditions, the cold gas efficiency of 38% is achieved. [ABSTRACT FROM AUTHOR]

In this paper, effects of ash-forming temperature on recycling property of bottom ashes obtained from combustion of rice straw and rice husk were investigated. Ash solubility and element solubility were chosen for representing recycling property and they were determined based on the measurement of element content using X-ray Fluorescence Spectrometer (XRF). Results show that water solubilities of both bottom ashes decrease with increasing ash-forming temperature and the water solubility of rice straw ash is higher than that of rice husk ash. Investigations also reveal that the easily soluble elements are K, Cl, S, Na in rice straw ash and K, S in rice husk ash. While the solubilities of K and Na decrease with the increasing ash-forming temperature, the solubilities of S and Cl are independent upon this temperature. Difference between the two ashes indicates that the recycling property of ashes from different parts of the same crop varies considerably. [ABSTRACT FROM AUTHOR]

Highlights: [•] H2 gas produced from the pyrolysis of rice straw is measured at different powers. [•] H2, CO2 and CO are the main gas products in the pyrolysis of rice straw. [•] The optimum concentration of the hydrogen production is 56.08% at a power of 1000W. [ABSTRACT FROM AUTHOR]

The increase in kitchen waste (KW) generation and irresponsible rice straw (RS) disposal has accentuated problems regarding environmental pollution and resource wasting. Although anaerobic co-digestion has been shown to be a more efficient strategy for bioenergy production than single digestion, there is still significant resistance to its application and diffusion owing to RS collection and many related factors in practice. Therefore, this study proposes a cooperative scheme for the cross-regional problem involving authorities and disposal plants. Subsequently, a bi-level multi-objective programming is developed to express the complexity of conflicts relationship in a multi-hierarchical problem and to achieve economic development, environmental protection and societal satisfaction in the bioenergy optimization process. A practical case study is then investigated to demonstrate the applicability of methodology in co-digestion deployment and resource recovery improvement, whereby scenario analyses are conducted by adjusting associated parameters. The practical application observed that (1) RS purchase was positively correlated with carbon reduction and social satisfaction targets, while excessive pursuit of social satisfaction resulted in a rebounding of carbon emissions; (2) the most popular mix ratios in disposal plants were 4:1 and 3:1, but they favor the latter when RS is readily available in sufficient quantities. Finally, some targeted suggestions are proposed for all stakeholders, which are expected to be a reference for potential users in other areas. • Anaerobic co-digestion is an efficient technology to convert kitchen waste into fuel. • Rice straw collection was made easier through the cooperative scheme. • Equilibrium optimization between economy, environment, and society is achieved. • A bi-level model is a preferable option to resolve multi-stakeholder conflicts. • Biogas production efficiency is not the sole determinant of optimum mixing ratio. [ABSTRACT FROM AUTHOR]

Highlights: [•] The natural rice straw was hydrolyzed to glucose and then glucose was hydrogenated in one pot. [•] The hydrogen was self-generated by in situ ethanol steam reforming. [•] The avoidance of high pressure hydrogen made the process more feasible and practical. [Copyright &y& Elsevier]

Highlights: [•] Reactivity evolution of rice straw char during char–NO reaction were studied. [•] Surface area development cannot account for evolution of original rice straw char. [•] Minerals transformation plays an important role on char reactivity evolution. [•] Relationship between reactivity and minerals concentration was given. [ABSTRACT FROM AUTHOR]

Abstract: Fast depletion of fossil fuels with high fluctuating market prices has made the hunt for alternate resources for the production of transportation fuels mandatory. Our approach is to utilize rice straw as feedstock for the production of alcoholic biofuels. In this paper, we have compared the effect of various pretreatment processes on rice straw, viz. physical (steam under pressure) and chemical (acid) and enzymatic treatments as a precursor to ABE fermentation for production of biobutanol. Glucose analysis was done by quantification of glucose content spectrophotometrically via Glucose assay kit. The rice straw hydrolyzate produced through pretreatment was allowed to undergo anaerobic fermentation, using C. acetobutylicum MTCC 481. The yield and productivity of ABE solvents (acetone, butanol and ethanol) was calculated using HPLC. The ABE yield produced using hydrolyzate obtained through enzyme assisted acid hydrolysis, viz. acetone: 0.11, butanol: 0.861, ethanol: 0.05, was found to be the best among all experiments. [Copyright &y& Elsevier]

Highlights: [•] ABE production from rice straw was significantly improved by alkali and acid pretreatments. [•] After pretreatments, over 67% of glucan and 17% of xylan were recovered. [•] After pretreatment, more than 163g glucose was produced from each kg of rice straw. [•] More than 44g butanol and 17g acetone were produced from each kg of rice straw. [Copyright &y& Elsevier]

Abstract: Co-liquefactions of a Chinese Shenfu sub-bituminous coal (SFSBC) and rice straw (RS) over four different coal liquefaction catalysts were carried out and the co-liquefied product preasphaltene (PA) was characterized by elemental analysis, FTIR and gel permeation chromatograms (GPC) measurements. It was found that the four catalysts gave different catalytic activities in the liquefaction of SFSBC and RS alone. Co Mo/Al2O3 and /ZrO2 promoted the oil formation for RS liquefaction due to their solid acidic property, but FeS+S gave the highest catalytic activity for the liquefaction of SFSBC among the four catalysts used in this study. There existed a positive synergistic effect in the co-liquefaction of SFSBC and RS, and the main synergistic interaction was reflected by the promoted formation of oil and PA. The catalytic activities of the four catalysts in the co-liquefaction were quite different from their catalytic activities in the individual liquefaction of SFSBC and RS. FeS gave the lowest catalytic activity for the coal liquefaction alone among the four catalysts, but had the highest promotion to the synergistic effect in the total yield of liquefaction products in the co-liquefaction of SFSBC and RS. /ZrO2 diminished this synergistic effect for the co-liquefaction of SFSBC and RS due to its solid acidic property. It was found that the four catalysts used have higher catalytic activity for the PA, which is from coal liquefaction and converting this part of PA into AS and oil fraction. The average molecular weights of PAs from /ZrO2 and Co Mo/Al2O3 catalysts were lower than those of PAs from FeS and FeS+S catalysts, suggesting that the catalytic hydrogenation activities of /ZrO2 and Co Mo/Al2O3 are higher than those of FeS and FeS+S catalysts. [Copyright &y& Elsevier]

Abstract: Newly isolated Sistotrema brinkmannii and Agaricus arvensis were co-cultured using rice straw (20g/L) as a carbon source and yeast extract (10g/L) as a nitrogen source to produce high levels of cellobiohydrolase (12.6U/mL), β-glucosidase (21U/mL), and endoglucanase (16.4U/mL). The filter paper activity (FPU) of the mixed fungal culture was enhanced (1.61FPU/mL) compared to that of S. brinkmannii (0.3FPU/mL) or A. arvensis (0.5FPU/mL) monoculture. Enzyme loading, substrate concentration, pH, and temperature were optimized by response surface methodology (RSM) to improve the saccharification yield of alkali-pretreated plant biomasses. The highest enzymatic hydrolysis (76.7%) was obtained from Pinus densiflora under the following conditions: crude enzyme loading 22.5FPU/g-substrate, substrate 3.75%, temperature 35°C, and pH 5. The enzymatic hydrolyzate of pretreated P. densiflora was used for ethanol production using Saccharomyces cerevisiae, Pichia stipitis, and a co-culture of both the strains. The co-culture of S. cerevisiae and P. stipitis produced 23% more ethanol than that produced by S. cerevisiae alone and 38% more ethanol than that produced by P. stipitis alone. This study shows the potential of exploiting a microbial consortium for the cost-effective production of cellulases for bioethanol processes. [Copyright &y& Elsevier]

Abstract: Flow property of particles is one key factor in influencing the co-utilization of biomass and coal in an entrained flow gasifier. In this paper, the flow properties of the blended particles of rice straw and coal were systematically studied. The results showed that Hausner ratio cannot indicate flow ability of the blends because of the particle segregation during shaking. Both the tangent of the angle of internal friction and α (the mean value of the angle of internal friction and angle of repose) of the blends display a linear increase with the mass fraction of rice straw, and their increments are almost the same. Moreover, the influence of particle shape of rice straw particles on both two kinds of angles was also found by introducing an orientation revision parameter, and the detailed expressions were also obtained. [Copyright &y& Elsevier]

Abstract: Pyrolysis of raw rice straw (RS), water-washed rice straw (WRS) and acid-washed rice straw (ARS) was conducted on a fixed bed reactor. A standard detergent method was used to determine the fiber constituents including neutral detergent solute (NDS), hemicellulose, cellulose and lignin in RS, WRS, ARS and their chars. Results showed that water washing removed most alkali metals (K and Na) from RS, and acid washing removed almost all alkali and alkali earth metals (K, Na, Ca and Mg); meanwhile, either washing eluted a portion of NDS but nearly unaffected hemicellulose, cellulose and lignin in RS. Attempts were made to assess the intermingled influences of the internal alkali and alkali earth metals (AAEMs) and the varied organic matter on the pyrolysis behaviors. It was revealed that the AAEMs inherent in RS had multiple impacts on the product distribution, the decomposition characteristics of fiber constituents, and the compositions of all gaseous, liquid, and char products. [Copyright &y& Elsevier]