Residue Yield Research Articles

Long-term conservation agriculture increases nitrogen use efficiency by crops, land equivalent ratio and soil carbon stock in a subtropical rice-based cropping system

Conservation Agriculture (CA) is still a relatively new approach for intensively cultivated (3 crops yr -1 ) rice-based cropping systems that produce high crop yield and amounts of residues annually. With the recent development of transplanting of rice into tilled strips on non-puddled soil, CA could become feasible for rice-based cropping patterns. However, the effect of increased retention of crop residues on crop response to nitrogen (N) fertilization rate in strip tilled systems with the transplanted rice and other crops grown in the annual rotation is yet to be determined. For nine years, we have examined the effects of soil disturbance levels - strip tillage (ST) and conventional tillage (CT), two residue retention levels –15% residue by height (low residue, LR) and 30% residue (high residue, HR) and five N rates (60%, 80%, 100%, 120%, and 140% of the recommended N fertilizer doses (RFD)) for a rice-wheat-mungbean cropping sequence. The 100% RFD was 75, 100 and 20 kg N ha -1 for rice, wheat, and mungbean, respectively. Rice yields were comparable between the two tillage systems for up to year-6, wheat for up to year-3 but mungbean yield markedly increased in ST from year-1; however, the land equivalent ratio increased from year-1, principally because of higher mungbean yield. Introduction of ST increased land equivalent ratio by 26% relative to CT, N use efficiency and partial factor productivity. Nitrogen fertilizer demand for maximum yield in ST was increased by about 10% for rice and 5% for mungbean but decreased by 5% for wheat. Although fertilizer N demand had increased in ST system due to higher yield than CT, the N requirement declined by50–90% when the same yield goal is considered for ST as for CT. The soil organic carbon stock (0–15 cm) after 8 years increased from 21.5 to 30.5 t ha -1 due to the effect of ST plus high crop residue retention. Annual gross margin increased by 57% in ST over CT practice and 26% in HR over LR retention. In conclusion, after 9 years practicing CA with increased residue retention under strip tillage, the crops had higher N use efficiency, grain yield, land equivalent ratio and annual gross margin in the rice-wheat-mungbean cropping system while the N fertilizer requirement increased minimally. • Strip tillage (ST) with residue retention increased crop profitability. • Adoption of ST practice increased N use efficiency. • The ST practice required about 10% more N but produced higher rice crop yield. • Strip tillage plus residue retention increased SOC stock by 9 t ha -1 over 8 years.

Molecular Characteristics of Jimusaer Shale Oil from Xinjiang, China.

Increasing attention is currently obtained by the exploitation and utilization of unconventional energy sources globally. Jimusaer shale oil (JSO) was prepared by dry distillation from oil shale in Jimusaer, Xinjiang, China. Using n-heptane and toluene as solvents, saturate (SA), aromatic (AR), resin (RE), and asphaltene (AS) samples were produced from JSO. Samples were subsequently analyzed by elemental analysis (EA), thermogravimetric analysis (TG-DTG), infrared analysis (FT-IR), high-performance gel chromatography (GPC), and nuclear magnetic resonance (1H-NMR and 13C-NMR). In terms of basic properties, element content, classification of combustible minerals, and refining performance, JSO, which has a high H/C value, low carbon residue yield, low metal content, and excellent refining-processing performance, is considered a high-quality shale oil compared with the shale oil produced in other areas. The refining performance of JSO is even comparable with petroleum. According to column chromatography, the contents of SA, AR, RE, and AS in JSO are 54.32, 18.86, 25.81, and 1.01%, respectively. The results of FT-IR and NMR (1H-NMR and 13C-NMR) demonstrated that the chain alkane or aromatic cycloalkyl substituents of SA, AR, and RE decrease sequentially, while the number of aromatic rings and cycloalkane rings and the degree of condensation increase sequentially. These results indicate that the chain alkanes with a small number of cycloalkanes are the main component of SA. The AR and RE contain more thick-ring aromatic hydrocarbons. According to GPC, the molecular weight (Mn) of JSO is 845 g·mol–1, and those of SA, AR, and RE are 702, 1107, and 2218 g·mol–1, respectively. The estimated molecular formulas (Maf) of JSO, SA, AR, and RE, which were calculated based on the combined results of GPC and EA, are C57.91H115.60O1.38N0.79S0.04, C48.02H101.79O0.69N0.85S0.03, C76.96H137.16O1.08N1.87S0.09, and C156.24H247.75O1.46N4.42S0.32.

Enhanced fire-proofing performance and crystallizability of bio-based poly(L-lactic acid): Dual functions of a Schiff base-containing synergistic flame retardant

Poly(L-lactic acid) (PLA) is a kind of important bio-macromolecule which can be prepared via fermentation of starch of maize and sweet potato. Flammability and extremely poor crystallizability limited its wide application. In this work, a novel Schiff base derivate (CP) was synthesized and, combined with ammonium polyphosphate (APP) as a synergistic flame retardant and nucleating agent to investigate its effects on LOI, UL-94 rating, thermal stability, combustion behavior and crystallizability of PLA. With loading of 5%CP/10%APP, PLA showed a significantly enhanced LOI and passed V-0 fire-safety rating with self-extinguish effect. PLA/5%CP/10%APP presented the lowest pHRR, THR and TSR, and highest char residue yield, FPI and FRI in cone calorimetry test, indicating an excellent flame retardancy effect, enhanced fire safety and longer escaping time in the fire. A continuous, compact and thick char layer structure formed as a protective barrier in combustion process, to enhance heat-insulating and oxygen resistance property, thermal stability and smoke-suppressing capacity of PLA. Flame retardancy mechanism was proposed and discussed based on comprehensive and in-depth characterization techniques. Also, 5%CP/10%APP presented a good nucleation effect to enormously increase crystallizability and shorten crystallization time of PLA.

A vanillin‐derived flame retardant based on 2‐aminopyrimidine for enhanced flame retardancy and mechanical properties of epoxy resin

AbstractIn order to give epoxy resin good flame retardance, a novel bio‐based flame retardant based on 2‐aminopyrimidine (referred to as VAD) was synthesized from renewable vanillin as one of the starting materials. Its structure was confirmed by NMR and mass spectra. The epoxy resins containing VAD were prepared by utilizing 4,4‐diaminodiphenylmethane (DDM) as a co‐curing agent, and their flame‐retardant, mechanical and thermal properties and corresponding mechanisms were studied. VAD accelerated the cross‐linking reaction of DDM and E51 (diglycidyl ether of bisphenol A). 12.5 wt% VAD made the epoxy resin achieve UL‐94 V‐0 rating and its limited oxygen index (LOI) value increase from 22.4% to 32.3%. The cone calorimetric testing results revealed the decline in the values of total heat release (THR) and peak of heat release rate (pk‐HRR) and the obvious enhancement of residue yield. A certain amount of VAD enhanced the flame inhibition, charring and barrier effects, resulting in good flame retardance of the epoxy resin. Furthermore, the tensile strength, flexural strength and flexural modulus of the epoxy resin with 12.5 wt% loading of VAD were 6.5%, 14.9%, 15.2% higher than those of EP, indicating the strengthening effect of VAD. This work guarantees VAD to be a promising flame retardant for enhancing the fire retardancy of epoxy resin without compromising its mechanical properties.

Improving the Heat and Ablation Resistance of Silicone Rubber Composites by Incorporating Hollow Microspheres.

For thermal protection materials (TPMs) which are used to protect space vehicles from extreme thermomechanical environments, the thermal conductivity of the original material and the char layer that has formed during ablation plays a significant role in determining the ablation performance. In order to investigate this, in this study, we introduced glass hollow microspheres (GHMs), phenolic hollow microspheres (PHMs), and acrylonitrile-methyl methacrylate copolymer hollow microspheres (AMHMs) into silicone rubber (SR), and the ablation performance of these composites was systematically studied. The thermogravimetric results showed that the residue yield of the SR composites was increased with the incorporation of the hollow microspheres. Compared to the SR composites without the hollow microspheres, the residue weight values under 800 °C (R800) of the SR composites with the 30 parts of fumed silica per hundred of the SR (phr) addition of GHMs, PHMs, and AMHMs were increased from 10.11% to 21.70%, 18.31%, and 20.83%, respectively. The ablation tests showed that the addition of the AMHMs enhanced the ablation performance of the SR composites because the linear ablation rates and the backplane temperature were clearly decreased when compared to the SR composites without the hollow microspheres. This work provides an effective and potential method for preparing thermal protection materials with an improved ablation performance.

Co-pyrolysis of paper mill sludge and textile dyeing sludge with high calorific value solid waste: Pyrolysis kinetics, products distribution, and pollutants transformation

Paper mill sludge (PMS) and printing and textile dyeing sludge (TDS) are two typical industrial sludge with high calcium content, high ash content and low calorific value. To attain effective removal of industrial solid waste, in this study, PMS and TDS are first pyrolyzed independently to study their thermochemical behavior. Results show that 600 °C is the optimal pyrolysis temperature for both PMS and TDS from the perspective of organics degradation. However, the yield and quality of pyrolysis oil and gas are still at low level due to the characteristics of high ash content and low organic content, which is not suitable for fuel recovery. Two kinds of organic solid wastes with high calorific value, duckweed (DW) and waste tire (WT), are co-pyrolyzed with PMS and TDS, which can effectively reduce activation energy and increase the yield of liquid and gas products. The most prominent is P1D1 pyrolysis gas, the production of CH4 and C2-C3 increased from 10.80 L/kg and 3.89 L/kg to 20.16 L/kg and 15.58 L/kg respectively, and the high calorific value also increased to 230.93 kJ/kg. The quality of pyrolysis liquid has been improved significantly as the declined N and O-heteroatom content (especially for P1D1 and T1W1) due to the inhibition effect of co-pyrolysis on the N/O migration into pyrolytic liquid. The solid residue from the co-pyrolysis of PMS and DW contains rich N-functional groups and can promote the conversion of pyridinic-N and pyrrolic-N to quaternary-N. Compared with independent pyrolysis, co-pyrolysis can promote the degradation of harmful organic matter in sludge. The addition of DW and WT co-pyrolysis reduced the solid residue yield of PMS by 19.9 wt% and 14.9 wt% (13.4 wt% and 10.5 wt% for TDS). This work provides inspiration for further understanding the safe disposal of PMS and TDS by pyrolysis.

Estimating maize harvest index and nitrogen concentrations in grain and residue using globally available data

Reliable estimates of crop nitrogen (N) uptake and offtake are critical in estimating N balances, N use efficiencies and potential losses to the environment. Calculation of crop N uptake and offtake requires estimates of yield of crop product (e.g. grain or beans) and crop residues (e.g. straw or stover) and the N concentration of both components. Yields of crop products are often reasonably well known, but those of crop residues are not. While the harvest index (HI) can be used to interpolate the quantity of crop residue from available data on crop product yields, harvest indices are known to vary across locations, as do N concentrations of residues and crop products. The increasing availability of crop data and advanced statistical and machine learning methods present us with an opportunity to move towards more locally relevant estimates of crop harvest index and N concentrations using more readily available data. The aim of this study was to investigate whether improved estimates of maize crop HI and N concentrations of crop products and crop residues can be based on crop data available at the global scale, such as crop yield, fertilizer application rates and estimates of yield potential. Experiments from 1487 different locations conducted across 31 countries were used to test various prediction models. Predictions from mixed-effects models and random forest machine learning models provided reasonable levels of prediction accuracy (R 2 of between 0.33 and 0.68), with the random forest method having greater accuracy. Although the mixed-effects prediction models had lower prediction accuracy than random forest, they did provide better interpretability. Selection of which method to use will depend on the objective of the user. Here, the random forest and mixed-effects methods were applied to N in maize, but could equally be applied to other crops and other nutrients, if data becomes available. This will enable obtaining more locally relevant estimates of crop nutrient offtake to improve estimates of nutrient balances and nutrient use efficiency at national, regional or global levels, as part of strategies towards more sustainable nutrient management. • Predictions of crop nitrogen (N) removal at national to sub-national scales will improve global nutrient budgeting. • Maize harvest index (HI), crop product N concentration (CPN) and crop residue N concentrations (CRN) were analyzed. • Predictor variables included crop product yield, fertilizer nitrogen application rates and yield potential. • Random forest (RF) models had greater prediction accuracy of HI, CPN and CRN compared with mixed-effects (ME) models. • Both methods could predict HI, CPN and CRN, but ME models were easier to interpret and extrapolate than RF models.

Elucidation of the interaction effects of cellulose, hemicellulose and lignin during degradative solvent extraction of lignocellulosic biomass

The degradative solvent extraction (DSE) method has been recently developed to deoxygenate and upgrade lignocellulosic biomass wastes into high-quality extracts with a variety of value-added applications. Lignocellulosic biomass is mainly composed of cellulose, hemicellulose and lignin, and the interaction of the three components during the DSE process still remains unclear and needs to be elucidated. Therefore, in this study, the synthetic component mixtures (cellulose/hemicellulose (CH), cellulose/lignin (CL) and hemicellulose/lignin (HL)) were firstly prepared with the model compounds (cellulose, hemicellulose and lignin), and the conversion characteristics of the component mixtures and the superposition of individual component during the DSE process under the same operating conditions were compared to reveal the interaction effect between the three components. The extract yields of cellulose, hemicellulose and lignin were 44.16%, 27.4% and 18.25% respectively, indicating that cellulose contributed mostly to the formation of the extract (the target product) compared with hemicellulose and lignin. Significant interactions were observed for cellulose/lignin and hemicellulose/lignin mixtures, while the interaction effect between cellulose and hemicellulose was relatively small. The interaction intensity between cellulose, hemicellulose and lignin was in the order of HL > CL > CH. The interaction between cellulose/lignin and hemicellulose/lignin promoted the thermal degradation of lignin. Specifically, the interaction between the hemicellulose and lignin mixture reduced the yield of residue by 9.26%. The interaction mechanism between the three components was discussed and revealed based on the detailed characterization of the DSE products. The interaction between the three components could facilitate the production of gaseous products (mainly CO2), indicating that the interaction between the three components significantly promoted the decarboxylation reaction. The interaction between two of the three components all inhibited the aromatization reaction and reduced the aromaticity of the extracts. During the DSE process of cellulose/lignin or hemicellulose/lignin mixtures, the small-molecular free radicals generated by the decomposition of cellulose or hemicellulose could occupy the active sites on lignin fragments, leading to the significant inhibition of the condensation reactions between different lignin fragments. These interactions leaded to the decrease of the extract yields and residue yields during the DSE process of cellulose/lignin or hemicellulose/lignin mixtures.

Effect of chemical dispersion on distribution of distillates cuts in various crude oil samples

The present paper reports on the distillation behavior of the neat and surfactants dispersed crude oils monitored through boiling point curves/ASTM curves. The surfactants used were cetyltrimethylammonium bromide (CTAB) as cationic, sodium dodecyl sulfate (SDS) as anionic, and Triton-X as neutral amphiphiles. Three crude oils including light (denoted as RCP-I), middle (denoted as RCN-II) and heavy oils (denoted as RCA-III) were studied using atmospheric pressure distillation. The distillation curves (the boiling temperature versus cumulative volume fraction distilled), at 10% (v/v) intervals, were constructed from the obtained results. The results revealed an increased volatility of the crudes in the presence of the surfactants and the samples yielded lighter products (gasoline and diesel range) when provided with surfactants. The dispersion of the RCA-III with SDS significantly increased the yield of light fraction to 58% and the yield of the residue decreased to 6%. The CTAB was effective in RCN-II crude which increased the yield of light fraction to 49%, and decreased the residue yield to 7%. The Triton X-100 also proved to be more effective in RCN-II crude and gave 48 and 6% yields of light and residue fractions, respectively.

Mechanically robust and flame-retarded EPDM composites with high loading of Mg(OH)2 based on reversible crosslinking network from Diels-Alder reactions

Crosslinked EPDM/magnesium hydroxide (MH) composites are commercially materials, but the crosslinked EPDM/MH composites with high MH loading reported so far are difficult to achieve good flame retardant and mechanical properties at same time. In this paper, a thermoreversible crosslinking network based on Diels-Alder reaction between furan/acrylic acid and the Mg2+-carboxyl coordination between MH/carboxylic acid group was constructed in flame retardant EPDM composites containing high loading of MH. The composites were prepared via two steps, first, the EPDM-g-MAH was modified with furfurylamine to obtain furan functionalized EPDM(EPDM-g-FA), then a series of EPDM-g-FA/MH composites were prepared by blending EPDM-g-FA, MH and acrylic acid (AC) via two-roll milling and hot pressing process. It was revealed that the introduction of AC could not only promote the formation of thermoreversible crosslinking network, but also the coordination between MH/carboxylic acid group significantly restricts the MH agglomeration and improved the compatibility between MH and polymer matrix. Moreover, AC could act as a synergistic flame retardant, compared with AC-free composite (AC-0), the tensile strength of the composite containing 10 phr AC (AC-10) was increased from 10.5 to 13.9 MPa, and the Young's modulus increased from 41.8 MPa to 46.8 MPa. The LOI of the composite containing 15 phr AC (AC-15) was increased from 29.8 to 33.3%, and the char residue yield at 700 °C of AC-15 increased from 36.2 to 39.9% compared to AC-0, meanwhile the char residues of AC-15 was more compact and continuous. All samples with AC loading showed higher thermal stability and activation energy of degradation. More importantly, the EPDM-g-FA/MH composites with thermoreversibly crosslinking showed good reprocessability.

Conversion of polyethylene terephthalate waste in the presence of cobalt compound into highly-porous metal-carbon nanocomposite (c-PET-Co)

A method for conversion of polyethylene terephthalate (PET) waste into cobalt-carbon nanocomposites is proposed. The main feature of the procedure is the simultaneous formation of highly porous PET-derived carbon support and cobalt nanoparticles. Pyrolysis of a joint precursor obtained by mixing the three main components (PET, cobalt nitrate and KOH) in dimethyl sulfoxide results in the formation of a metal-carbon nanocomposite. The effect of the amount of KOH introduced on the structural properties of nanocomposites has been studied. It was shown that the weight ratio of PET:KOH affects both the porous characteristics of the material and the size of the cobalt nanoparticles. Also, the amount of alkali affects the yield of nanocomposite, both the yield of carbon residue, increasing it from 11.6 to 20.7 wt%, and the content of metal in the composite, which was in the range of 18.5–28.4 wt%.

Carbon dioxide-mediated thermochemical conversion of banner waste using cobalt oxide catalyst as a strategy for plastic waste treatment

In this study, the effects of CO2 thermochemical agent and a metal oxide catalyst (Co3O4) on thermochemical banner waste conversion were explored. The results revealed that compared to the non-catalytic conversion of banner waste under N2 environment, the conversion under CO2 yielded more non-condensable gases owing to an enhanced thermal cracking of volatiles. In addition, the CO and CH4 yields at >700 °C in CO2 increased considerably owing to the reverse water–gas shift reaction and CO2 methanation. The CO2 agent reduced the yields of condensables (e.g., benzoic acids, phthalic acids, esters, biphenyls, fluorenes) and decomposition residue (e.g., char and wax), which could be attributed to the enhancement of the thermal cracking of volatiles evolved during the banner waste conversion by CO2 and the C–H and O–H bonds present in the feedstock. In addition, the Co3O4 catalyst promoted the decarboxylation reaction under N2 environment, whereas it promoted the methanation and reverse water–gas shift reaction under CO2. This indicates that compared to the non-catalytic CO2-assisted banner waste conversion, the use of CO2 for the conversion of banner waste in the presence of Co3O4 significantly increased the yields of CH4 and CO. Furthermore, Co3O4 promoted the thermal cracking of polyester bond, thus decreasing the yields of long-chain chemical compounds. In addition, the simultaneous use of Co3O4 catalyst and CO2 agent minimized the formation of char and wax. For all cases (N2 versus CO2, non-catalytic versus catalytic), an increase in temperature enhanced the total permanent gas yield and decreased the yields of condensables, char, and wax. The findings of this study revealed the importance of the synergistic use of Co3O4 catalyst and CO2 agent for the plastic waste upcycling, such as banner waste.

Process flowsheet for extraction of Fe, Al, Ti, Sc, and Ga values from red mud

A comprehensive process flowsheet is investigated to recover metallic values from red mud with high-purity products such as alumina, silica, ferrous oxalate, titania, and Sc-Ga containing purified solution. The carbonated red mud leached in 1 M hydrochloric acid at 50 °C for 1 h dissolves 44.5% Al and 51% Si, followed by 2 M oxalic acid leaching at 90 °C for 2.5 h yielding 61% Fe and 46–48% Sc and Ga dissolution. High-purity ferrous oxalate product is retrieved from the leach solution, and the Sc and Ga ions report to the solution. Titanium enriched residue is baked with 1 mL/g sulfuric acid at 300 °C for 1 h, forming TiOSO4, Fe2(SO4)3, and Al2(SO4)3 phases, followed by water leaching. 64.5% Ti and ∼ 27% Fe dissolution is attained, and solution contains Fe (7.47 g/L), Ti (3.09 g/L), Al (2.44 g/L), Si (0.17 g/L), Sc (2 mg/L), and Ga (3 mg/L) ions. Thermal hydrolysis of solution recovers titania precipitate (96.9% purity), and the solution after hydrolysis contains Fe, Sc, and Ga values. The overall metal extraction (84% Fe, 79% Ti, 92% Al, 78% Sc, 89 % Ga) in the proposed flowsheet is higher compared to direct acid baking process (51% Fe, 65% Ti, 89% Al, 51% Sc, 48 % Ga). Products recovered include high-purity silica (4.8 wt%), alumina (9.3 wt%), Fe(II) oxalate (20.7 wt%), titania (8.9 wt%), and a final residue yield of 12.6 wt%. Microwave exposure at 2 kW for 7 min improves the dissolution of the Sc (84%) and Ti (85.5%). H2 reduction at 450 °C, 30 min converted hematite to magnetite and increased Fe dissolution to 90%. Red mud's mineralogical and composition modification by magnetic separation, reduction, and microwave exposure were ineffective to improve selective dissolution.

Lignin removal improves xylooligosaccharides production from poplar by acetic acid hydrolysis

Organic acid hydrolysis is a potential method for xylooligosaccharides (XOS) production from lignocelluloses. However, the effect of lignin content on XOS production using organic acid hydrolysis remains unclear. In this work, the effect of delignification on XOS production from poplar by acetic acid (AC) hydrolysis was investigated. Hydrogen peroxide-acetic acid (HPAC) pretreatment catalyzed by 0–200 mM H2SO4 (HPAC0–HPAC200) removed 21.6–86.5% of lignin in poplar. HPAC pretreatment increased the xylan accessibility to AC solution, thus increasing the xylan removal during AC hydrolysis. An appropriate delignification (61.7%) resulted in the highest XOS yield of 37.4% by AC hydrolysis, increased by 29.9% compared to the optimal XOS yield (28.8%) from raw poplar. After alkaline post-incubation, the glucose yield of poplar residue rose from 57.1% to 78.6%. This work developed a delignification process to efficiently improve XOS and monosaccharides production from poplar.

Upgrading of polyethylene to hydrocarbon fuels over the Fe-modified Pt/Al2O3 catalysts at a mild condition without external H2

Upcycling of waste plastic is an emerging topic in environmental chemical and process engineering. In this work, we investigated the pyrolysis of polyethylene (PE) over Fe-modified Pt/Al2O3 catalysts in the absence of external H2 to produce hydrocarbon fuels at a mild condition (330℃). The critical interest is to achieve the mild conversion of PE by using the bimetallic catalyst to generate in-situ H instead of external H2 for hydrogenolysis. Results show that a slight impregnation of Fe on Pt/Al2O3 (Fe/Pt = 0.25) can improve the oil yield and light oil selectivity as well as promote the formation of aromatics and alkenes in oil after PE pyrolysis in a batch reactor. Multiple active sites including Pt, Fe and Lewis acid site of Al2O3 work systematically to drive the tandem catalysis without H2. The Pt plays the major role in PE pyrolysis via hydrogenolysis assisted by in-situ generated H, but shows the mutual inhibition with the acid site of Al2O3 that is contributive to PE cracking via a traditional carbocation chemistry. Fe modification on Pt/Al2O3 plays multiple roles in catalysis: promotes cyclization reaction, benefits the hydrogenolysis activity of Pt by providing active H during aromatic formation, and decreases catalyst acidity to reduce gas production. However, an over-impregnation of Fe (Fe/Pt = 1) partially covers the Pt sites, resulting in the decrease of fuel oil production but an increase in residue yield due to the deactivation of Pt sites. The post-reaction catalyst can be almost completely regenerated after combustion and reduction.

Production of bio‐polyurethane (BPU) foams from greenhouse/agricultural wastes, and their biodegradability

AbstractThe exploration of effective utilization of greenhouse wastes is challenging. This paper demonstrates a hydrothermal treatment approach involving the co‐liquefaction of greenhouse wastes with agricultural residue in a mixed solvent of water and ethanol in the presence of a base catalyst, to convert greenhouse wastes and corn stalk into bio‐oil/bio‐polyol at a very high yield of 57.2%, accompanied by a very low yield of solid residue. This bio‐oil (hydroxyl number: 305 mg KOH/g) was successfully used as bio‐polyol to substitute up to 50% petroleum‐based polyol for the preparation of bio‐polyurethane (BPU) foams. The biodegradability of the BPU foams was also studied by incubation with Dyella sp. for a period of 8 weeks. The weight loss, Fourier‐transform infrared (FTIR) spectra, thermogravimetric analysis (TGA) results, and scanning electron microscopy (SEM) images of foam samples were collected and analyzed. The BPU foams exhibited much better biodegradability than the petroleum‐based polyurethane (PU) foam. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd

Study on Selective Preparation of Phenolic Products from Lignin over Ru–Ni Bimetallic Catalysts Supported on Modified HY Zeolite

The catalytic depolymerization of organic solvent lignin with the prepared catalyst 2.5Ru–10Ni/Al-HY was investigated in a high-pressure reactor. Effects of different catalysts, temperature, time, recyclability for catalyst, and solvents on the catalytic performance were explored. The optimal reaction conditions were reaction time 5 h and temperature 280 °C in ethanol solvent. As a result, the highest yield of phenolic monomers was 20.2 wt %, the yield of solid residue was only 4.8 wt %, and the gas products were CH4, C2H6, and CO mainly. With the increase of cycle times, the catalyst had no obvious deactivation, indicating a unique cycle stability. Through NMR characterization of lignin and depolymerization products, it was found that the signals of the original structures (A, B, and C) in lignin disappeared after reaction. According to the analysis of the reaction path, the depolymerization of lignin mainly included the depolymerization of lignin into reaction intermediates and the formation of phenolic compounds by breaking chemical bonds. This research showed a method for preparing phenolic products by the molecular sieve catalyzed depolymerization of lignin.

Gasification characteristics of a simulated waste under separate and mixed atmospheres of steam and CO2

Downdraft gasifier is attractive for small-scale solid waste treatment, but the gasification characteristics are worthy of deep research. In this study, a two-stage continuous feeding apparatus was developed to examine the effect of moisture content of the mixed feedstock on co-gasification. Furthermore, considering the effect of CO2 from flue gas, the gasification experiments were carried out when CO2 participated in the gasification alone or in a mixed atmosphere of CO2 and steam. The pyrolysis residue plays an essential role in the gasification with steam, which can improve the syngas yield, especially the H2 yield reaches 0.345 m3/kg when steam and feedstock mass ratio (S/F) is 0.8. CO2 is inferior to steam in promoting H2 formation. But when CO2 and feedstock mass ratio (C/F) rises from 0.74 to 1.48, the gas yield increases from 60.52% to 77.15%, and the yields of tar and residue cut down correspondingly. CO2 is still an alternative gasifying agent, which can partially substitute steam in the gasification process. However, when CO2 coexists with a small amount of steam (S/F = 0.4), introducing excessive CO2 (C/F = 1.48) will intensify the competition between steam and CO2.

Pyrolysis Behaviors and Residue Properties of Iron-Rich Rolling Sludge from Steel Smelting.

Iron-rich rolling sludge (FeRS) represents a kind of typical solid waste produced in the iron and steel industry, containing a certain amount of oil and large amounts of iron-dominant minerals. Pyrolysis under anaerobic environment can effectively eliminate organics at high temperatures without oxidation of Fe. This paper firstly investigated comprehensively the pyrolysis characteristics of FeRS. The degradation of organics in FeRS mainly occurred before 400 °C. The activation energy for pyrolysis of FeRS was extremely low, ca. 5.44 kJ/mol. The effects of pyrolytic temperature, atmosphere, heating rate, and stirring on pyrolysis characteristics were conducted. Commonly, the yield of solid residues maintained around 85 wt.%, with approximately 13 wt.% oil and 2 wt.% gas. Due to the low yield of oil and gas, their further utilization remains difficult despite CO2 introduction which could upgrade their quality. The solid residues after pyrolysis exhibited porous properties with co-existence of micropores and mesopores. Combined with the high content of zero-valent iron, magnetic property, hydrophobic characteristic, and low density, the solid residues could be further utilized for water pollution control and soil remediation. Moreover, the solid residues were suitable for sintering to recover valuable iron resources. However, the solid residues also contained certain heavy metals, such as Cd, Cr, Cu, Ni, Pb, and Zn, which might cause secondary pollution during their utilization. In particular, the toxic Cr possessed high content, which should be treated with detoxification and removal. This paper provides fundamental information for pyrolysis of FeRS and utilization of solid residues.

Filling the Protein Gap in Ghana: The Role of Soy

The study assessed the nutrient value and desirability of eight improved soybean varieties, for use in soymilk, tofu and as an ingredient to enhance staple foods. The soymilk, tofu, and soybean residue (okara) yields were determined across all varieties. The okara was subsequently used in composite with cassava, as a recipe refinement of gari, a popular cassava-based ready-to-eat food. Multiple composite ratios were compared against a control of 100% cassava gari; 80% cassava: 20% okara, 70% cassava: 30% okara, and 50% cassava: 50% okara. The soymilk and tofu from the various varieties and okara enriched-gari were also evaluated for proximate and sensory qualities (n = 50) using standard protocols. No differences (p > 0.05) existed among soybean varieties in terms of soymilk (p = 0.55; 13.0–14.1 L), tofu (p = 0.05; 0.12–0.15 kg/L) or okara (p = 0.08; 3.17–3.97 kg) yields. The proximate parameters evaluated for soymilk did not vary significantly (p > 0.05) among varieties. However, for total solids (3.33–7.93°Brix; p < 0.01) there were significant differences. Generally, there was an increasing trend in the crude protein, moisture, crude fat and total ash contents for the okara-enriched gari as the okara inclusion increased from 20 to 50%. Thus, the crude protein content of the 50% okara-enriched gari, the formulation with the highest okara incorporation was almost 11-times higher than the 100% cassava gari. The swelling capacity of the okara-enriched gari ranged from 3.29–5.47 and for water holding capacity 439.7–482.1%. The okara-enriched gari was equally preferred by consumers, except for colour which consumers were mostly indifferent towards. The 50%-okara enriched gari composite was compared equally with 100% cassava gari control. The sensory data showed that the “Favour” soybean variety was desirable for soymilk production while Salintuya 1 was desirable for tofu production. Recipe refinements using the desired varieties and compositing okara with cassava may help fill the protein gap among the vulnerable group in Ghana by improving the protein quality of ready-to-eat foods such as gari.