Pigeon Pea Stalk Research Articles

Optimized thermal pretreatment for lignocellulosic biomass of pigeon pea stalks to augment quality and quantity of biogas production

By applying heat to the feedstock during the thermal treatment of biomass for the production of biogas, the organic material's biodegradability can be greatly increased. Biogas production is a huge research area for alternate energy production technology. Increased biodegradability, improved methane yield, pathogen, and weed seed destruction, and overall process efficiency are all benefits of this type of pretreatment. It is a useful pretreatment technique for maximizing the production of biogas because it can decrease inhibitory compounds, and increase the digestibility of biomass. This work focused on increasing the efficiency of biogas production from lignocellulosic biomass of pigeon pea stalks by a novel thermal pretreatment. The pigeon pea stalk is initially imposed to physical pretreatment (PT) by an automatic hammer mill which is considered as a base for comparing performance. Thermal pretreatment was carried out for one hour, and two hours durations at different temperatures like 100 °C, 125 °C, 150 °C, 175 °C, and 200 °C. Compared to physically pretreated pigeon pea stalks, 200ᴼC thermal pretreated pigeon pea stalks for two hours have produced 88.41 % higher biogas, 16.14 % increase of cellulose, 19.9 % higher volatile solid removal, and 3.94 % lesser lignin. The enhanced chemical characteristics were ensured by analyzing the chemical composition variations through the FTIR, XRD, and SEM images. So, this is recommended for enhanced biogas production.

Assessment of agro-residues as biochar feedstock: Cotton stalk, soybean straw, and pigeon pea stalk

Assessment of agro-residues as biochar feedstock: Cotton stalk, soybean straw, and pigeon pea stalk

Utilizing Waste Cotton/Pigeon Pea Stalk Fibers Composites for Enhanced Sound Absorption and Insulation in Automotive Interiors

ABSTRACT This study investigates the synthesis and characterization of composite materials, pigeon pea stem, and cotton fibers blended in different ratios such as 100/0, 70/30, 60/40, 50/50, 30/70, and 0/100. These composite materials were produced using a compression molding technique. According to ASTM standards, the acoustics, thermal conductivity, and physical characteristics of the composite samples were tested to assess their qualities. The impedance tube method detailed in ASTM E1050 was used to determine the sound absorption coefficients (SAC) for acoustics. The SAC values were measured at six frequencies such as 125, 250, 500, 1000, 2000, and 4000 Hz. The results showed that composite samples made from waste cotton and pigeon pea demonstrated sound absorption values of greater than 80%. Superior sound insulation and absorption, moisture absorption, fiber properties have also been demonstrated by waste composites. Especially, the waste cotton/pea stalk waste fiber composites achieved over 75% sound absorption, while the waste 28% composites performed well in terms of sound absorption, moisture absorption, and fiber properties. Even in humid conditions, the composite samples constructed from used cotton and pigeon pea stalks demonstrated good moisture resistance without reducing their insulating qualities. Soundproofing barriers are composite layers of foam or pigeon pea/cotton.

Comparative techno-economic and life cycle assessments of single and intercropped-mixed feedstocks-based biorefineries for profitable and cleaner production of energy

The role of intercropped mixed feedstocks (IMF) in advancing biorefineries is rarely studied. However, as opposed to conventional single feedstocks (SF) from monocropping systems (MCS), IMFs could potentially enhance the economic profitability of biorefineries by reducing the cost of feedstock transportation and overall operations due to high feedstock yield/ha and fewer inputs e.g., diesel. In addition, IMFs could improve environmental performance by minimizing emissions associated with feedstock farming inputs (e.g., fertilizer), transportation (e.g., diesel, and tear & wear), and overall operational requirements. Furthermore, intercropping systems (ICS) could mitigate feedstock yield uncertainties and ensure stable feedstock supply because legumes (e.g., pigeon peas) are drought-resistant and inhibit pests & diseases when intercropped with maize. Nonetheless, the actual benefits of IMFs must be quantified. Therefore, techno-economic and life cycle assessments were done, using the Malawian economic context, to evaluate IMFs of maize stover (MS) and pigeon pea stalks and leaves (PPSL) for ethanol, electricity, and biogas production in varying biorefinery capacities of 156 000 and 2184 000 mt/y. Four scenarios were investigated; MS from MCS (S1), MS from ICS (S2), MS and PPSL from ICS (S3), where PPSL was dedicated for combined heat & power (CHP), and MS and PPSL from ICS where MS was dedicated to CHP (S4). The biorefinery systems were simulated in Aspen Plus ® to obtain mass and energy balances (MEB) which were used in assessing economic performance via biorefinery gate feedstock cost (BGFC), net present value (NPV), and minimum product selling price (MPSP). BGFC was evaluated by aggregating the cost of buying feedstocks, labor, milling, baling, and transportation. Transportation cost was computed via summation of the cost of fuel, driving labor, depreciation, and maintenance influenced by transportation distance and feedstock yield/ha. MEBs were also used as input and output data in SimaPro software to estimate emissions in terms of fossil resource depletion (FRD), global warming potential (GWP), terrestrial acidification (TA), and freshwater eutrophication (FWE). The IMFs improve biorefineries' economic performance by reducing feedstock logistical cost and MPSP, and environmental performance by reducing FRD, GWP, TA, and FWE. For example, BGFC, MPSP & FRD for IMF's S3 were $228 million/t, $2.28/L & 135 kg oil eq/mt, respectively, compared to $258 million/t, $2.37/L, and 146 kg oil eq/mt respectively for MSF's S1 at 2184 000 mt/y. Thus, IMF improved BGFC, MPSP, and FRD by 12, 5, and 8%, respectively. Therefore, utilization of the IMFs can boost the economic and environmental performances of biorefineries.

ANN approach for the prediction of pyrolytic behaviour of pigeon pea stalk and insight into thermo-kinetics of pseudo components using RSM

Artificial neural network (ANN) is the widely used technique for prediction and modeling of complex processes. In this study, ANN was applied for predicting the complex pyrolysis behaviour by employing critical process parameters like heating rate (°C/min) and temperature (°C). Two anticipated variables in input layer were used to predict the derivative weight loss (%/°C) by propagating in twelve neurons. The model's reliability and adequacy were validated by the best training performance data recorded at 36 training epochs with an MSE value of 2.34 × 10−5. In order to estimate the thermo-kinetics of the Pigeon pea stalks (PPS), thermogravimetric analysis was done at four heating rates (10–40 °C/min). The TG-spectra were resolved into their pseudo components using deconvolution technique. The activation energy and pre-exponential factor were estimated by Friedman isoconversional method. In continuation, response surface method (RSM) was employed to explore the effect of process parameter on thermodynamic parameters ΔG, ΔH, and ΔS. The recorded statistical values illustrated the adequacy and robustness of the fitted model with anticipated variables. Pyrolytic reaction order was also determined for each pseudo components through master plot method.

Innovative bio-pyrolytic method for efficient biochar production from maize and pigeonpea stalks and their characterization

Agricultural residues in excess of livestock fodder are garnering global attention and stern concerns owing to their accountable share in environmental hazards due to the lack of effective disposal mechanisms and indiscriminate burning. Recycling these residues for biochar production using pyrolysis is a cost-effective and locally feasible technique which offers a twin-prong solution addressing both climate and soil health issues. This research work compares a portable kiln prototype that is affordable and easy to use, with a muffle furnace at three distinct pyrolytic temperatures (400 °C, 500 °C, and 600 °C) to produce biochar from the stalks of maize and pigeonpea. The biochar properties were characterized using Electron Microscopy-Electron Dispersive X-ray (SEM-EDX), X-ray Diffraction (XRD), Fourier Transmission Infrared Spectroscopy (FTIR), and Thermogravimetric Analysis (TGA). The findings indicate significant variations in biochar properties based on raw material source, pyrolytic method, and varied temperatures. Higher pyrolysis temperatures were found to reduce the amorphous organic phase and alter the ultrastructure of biochar, as evidenced by XRD analysis. SEM imaging showed macropores in oval and round shapes with crystalline deposits. The carbon content, as per EDX, decreased with increasing temperature, aligning with changes in functional groups. Edinburgh's stability test revealed that kiln biochar has more stable carbon content compared to biochar produced using muffle furnace and the stable carbon increased with the rise in temperature. A comparative analysis demonstrated that biochar quality at 400–500 °C in a muffle furnace was on par with that produced in the portable kiln at 400 °C. Therefore, considering the kiln's portability, efficiency, cost-effectiveness, and scalability, it is a promising decentralized method for biochar production, offering a cutting-edge solution for agricultural waste management and soil carbon enhancement.

Harnessing the potential of pigeonpea and maize feedstock biochar for carbon sequestration, energy generation, and environmental sustainability

Crop residues in agriculture pose disposal challenges and contribute to air pollution when burned. This study aims to use pigeonpea and maize stalks to produce biochar at different pyrolysis temperatures. Biochar can serve in carbon sequestration, as a soil amendment, and as an alternative fuel source. Pyrolysis was conducted at 400, 500, and 600 °C to examine the effects on physicochemical properties, fuel, and energy related properties. Increase in temperatures resulted in decrease of biochar yield, volatile matter, and O/C and H/C atomic ratios, while ash content and essential nutrients increased. Yield was observed to be higher in pigeonpea stalks derived biochar compared to maize stalks derived biochar at same pyrolysis temperatures. The yields of pigeonpea stalks derived biochar at 400 °C, 500 °C, and 600 °C are 34, 33 and 29%, respectively, and the yields of maize biomass-derived biochar at 400 °C, 500 °C, and 600 °C are 29, 28, and 26%, respectively. The organic carbon content is found to be higher in the biochar samples prepared at 600 °C, i.e., 10.44%, and 10.39% for pigeonpea and maize-derived biochar, respectively. The essential elements of biochar were increased with an increase in pyrolysis temperature except nitrogen which is conversely related to temperature. The biochar obtained through pyrolysis at 400 °C demonstrated superior characteristics compared to biochar produced at other temperatures. It exhibited a higher biochar yield, with approximately 84.60% for pigeonpea and 64.85% for maize fixed carbon content. Additionally, the energy retention efficiency was higher, reaching 67.33% for pigeonpea and 42.70% for maize-derived biochar at a pyrolysis temperature of 400 °C. The fixed carbon recovery efficiency was also notable at around 200.44% for PPS and 142.37% for maize biochar which is higher compared to biochar produced at other temperatures. Furthermore, the higher heating value (HHV) was approximately 30.75 MJ kg−1 for both the biochars, indicating their suitability as alternative solid fuels. A significant CO2 reduction potential of 84 CO2 eq kg−1 and 55 CO2 eq kg−1 was observed for pigeonpea and maize biochar, respectively. Hence, biochar is a promising and effective option for carbon sequestration, offering environmental benefits.Graphical

Stepped pyrolysis: A novel approach for enhanced adsorbency and carbon in Pigeon pea stalk char

This article introduces a novel technique, stepped pyrolysis, for thermal degradation of biomass. The differential thermogram (DTG) of pigeon pea stalk was deconvoluted into their intrinsic bioconstituents and these deconvoluted peaks were used to decide the different stages or steps to finalize the thermal protocol to be executed for stepped pyrolysis. The stepped pyrolysis and traditional pyrolysis of pigeon pea stalk were conducted and the characterisation of outputs was done. The obtained result for the char produced by the stepped pyrolysis method showed a reduction of 5% in the volatile matter and an increment of 5% in fixed carbon content, over the product of traditional pyrolysis. The stepped pyrolysis increased the iodine number by 17% while reducing the methylene blue values by 31% as compared to the traditional pyrolysis. A significant reduction in activation energy by 21% for FWO, 18% for KAS, and 26% for Starink methods were recorded for stepped, over traditional pyrolysis. The pyrolysis reaction mechanism of stepped and traditional pyrolysis methods followed the second-order (F2) and two-dimensional diffusion model (D2). The stepped pyrolysis method produced a better quality product with more micropores and carbon-rich char than the traditional method.

Ni-supported pigeon pea stalk biochar as a catalyst for ex situ tar cracking in biomass gasification

Ni-supported pigeon pea stalk biochar as a catalyst for ex situ tar cracking in biomass gasification

Comparative Analysis of Pigeonpea Stalk Biochar Characteristics and Energy Use under Different Biochar Production Methods

The disposal of crop residues from agricultural fields is often seen as a burden due to the difficulties involved. However, this study aims to turn pigeonpea stalks into biochar, which can serve as a fuel substitute and soil amendment to sequester carbon. Different pyrolysis methods were employed to investigate the variations in yield, physicochemical characteristics, and higher heating value (HHV) of biochar produced from pigeonpea stalks. The biochar produced using a muffle furnace exhibited higher fixed carbon and ash content. These characteristics make it beneficial for restoring degraded agricultural soils by enhancing carbon sequestration. In addition, the muffle furnace biochar demonstrated a total potential carbon ranging from 262.8 to 264.3 g of carbon per kilogram of biochar, along with a CO2 reduction potential ranging from 77.17 to 79.68 CO2 eq per kg. Both the European Biochar Certificate and the International Biochar Initiative confirmed the agronomic abilities of the biochar and its compliance with the highest quality standards for soil carbon sequestration, with 0.11 H/C and 0.7 O/C ratios. Furthermore, biochar produced by muffle furnace from pigeonpea stalks exhibited superior fixed carbon recovery efficiency (181.66 to 184.62%), densification (5.86 to 6.83%), energy density (1.77 to 2.06%), energy retention efficiency (54.80 to 56.64%), fuel ratio (18.95 to 22.38%), and HHV (30.66 to 32.56 MJ kg−1). Additionally, it had lower H/C and O/C ratios, suggesting its potential as an alternative solid fuel. The results of the characterization of biochar with scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) revealed that the biochar samples prepared with both the methods had carbonyl (C=O), C=C, and aromatic C-H functional groups; however, the biochar prepared in the muffle furnace had more porosity. In summary, this study highlights the potential of using pigeonpea stalks to produce biochar, which can be utilized as a renewable fuel substitute and soil amendment to sequester carbon. The biochar derived from the muffle furnace exhibited desirable physicochemical characteristics, high carbon content, and excellent energy properties, making it a promising option for various applications.

Pyrolysis of torrefied crop residue: Optimization using response surface methodology and benefits of bio-char in co-combustion with coal

The present study includes optimizing process parameters using response surface methodology (RSM) for the pyrolysis of torrefied pigeon pea stalk to maximize its bio-oil yield. Substantial improvements have been observed in terms of calorific value (29–34% increase), water content (29–33% decrease), and oxygen content (9–12% decrease) for the bio-oil obtained from the pyrolysis of torrefied biomass compared to raw biomass. The results obtained in the present study indicate that the torrefaction of raw biomass could increase the effectiveness of hydrodeoxygenation (HDO) significantly. Hence, it could help achieve desired properties even in a single stage HDO compared to two stages HDO, leading to substantial cost reduction. Furthermore, bio-char from torrefied biomass has a better fuel ratio (FR), less particulate emission, and higher fuel value index (FVI) compared to bio-char from raw biomass and shows better compatibility with bituminous coal in co-combustion. Also, as much as 13.4% and 41.7% reduction in required fuel feed rate and ash production rate have been observed for 60% blending of bio-char with bituminous coal. The yield of pyrolytic gas decreased; however, on the qualitative front, the concentration of CH4 and H2 increased with CO2 being decreased significantly.

Biopolymeric transitions under pyrolytic thermal degradation of Pigeon pea stalk

In this article, thermogravimetric analysis (TGA) is used to explore biopolymeric transitions in Pigeon pea stalks (PPS) at various heating rates (10, 20, 30 and 40 °C/min). The appeared transitions of TG-signals were analyzed in depth and discussed critically in terms of biopolymeric changes occurring within the major bioconstituents of PPS due to the influence of different heating rates. The intersection points of the deconvoluted conversion rate spectrum were taken as the stage transition points from one biopolymeric region to another. The stage transition points for hemicellulose to cellulose were at 328 °C and from cellulose to lignin at 356 °C, respectively, at a heating rate of 10 °C/min. This article is presenting the stage transition points first time and highlights the procedure of obtaining them using the conversion rate spectrum. The kinetics of individual bioconstituents of the PPS was also thoroughly investigated. The average activation energy was highest for hemicellulose 283–287 kJ/mol, followed by cellulose (134–137 kJ/mol) and lignin (30–41 kJ/mol). The pyrolysis of PPS followed the multistage reaction mechanism (F1 and A4) based on the Z-master plot technique.

Sustainable waste cotton and pigeon pea stalk fibers composite materials for acoustics and thermal properties

This study focuses on the development and characterization of pigeon pea stalk/cotton fibers mixed with a blend ratio of 50/50, 70/30, 30/70, 60/40, 100/0 waste cotton and 0/100 waste pea stalk composites are equipped with a compression molding system. The entire composite samples are tested for acoustics, thermal and physical parameters as per the American Society for Testing and Materials standard (ASTM). The sound absorption coefficients (SAC) were measured according to ASTME1050 by an impedance tube method, and the SAC over six frequencies 125, 250, 500, 1000, 2000, and 4000 Hz were calculated. The result revealed that the composite samples that are prepared from cotton/pigeon pea waste have confirmed more than 80% of the SAC and the waste composites provided the best insulation, sound absorption, moisture absorption, and fiber properties. The effect exposed that composites materials arranged from cotton/pea stalk waste fiber have established further than 75% by the sound immersion measure and the waste 28% composites handed the fashionable Appropriation, sound immersion, humidity immersion, and fiber materials. The waste cotton/pigeon pea stalk composite samples have satisfactory moisture resistance at high humidity situations without disturbing the insulation properties.

Overriding Investigation on Strengthening of Thermal Stability of Torrefied Pigeon Pea Stalk and Kinetic Compensation

This article aims to evaluate the pyrolytic behavior of torrefied biomass in order to resolve the logistic issue of the biomaterial and utilize it during idle time. In order to that, the thermal treatment of the raw pigeon pea stalk was done up to 250℃ in a reactor in an inert environment. The obtained solid biomaterial was subjected to the thermogravimetric analysis for four various heating rates (10, 20, 30, and 40℃/min) to investigate the changes occurring in thermal behaviour and kinetic parameters over the raw material. The deconvolution analysis of the thermogravimetric signals leads the study to an overriding investigation on thermal stability of the intrinsic bioconstituent. In addition, the kinetic triplet and thermodynamic parameters were estimated by employing the ICTAC recommended Ozawa-Flynn-Wall isoconversional method. The computed average activation energy level of the torrefied biomaterial (229 kJ/mol) was registered significantly higher than the raw pigeon pea stalk (139 kJ/mol). Also, the changes registered in thermodynamic parameters such as ΔG, ΔH and ΔS give a beneficial sign on the thermal stability of the existing bioconstituents. Torrefaction of the pigeon pea stalk enhances the kinetics and thermodynamic balancing of the biomaterial. The thermally established biomaterial can be stored for a longer period and it can utilize as the bioenergy generating feedstock during idle periods.

Development and Characterization of Pigeon Pea Stalk Fiber Reinforced Polylactic Acid Sustainable Composites

ABSTRACT This study focuses on the development and characterization of pigeon pea stalk fiber (PSF) reinforced (10, 20, 30, and 40 wt.%) polylactic acid (PLA) sustainable composites. In particular, the tensile, compression, flexural, impact, shear strength, and hardness characteristics were studied as mechanical properties, while other characterizations included dynamic mechanical analysis, density, water absorption, crystallinity index, and morphology studies were also examined to get a more comprehensive understanding of these green composites. From the results of mechanical properties, the optimal particle loading was up to 30 wt.%, and these properties compare well with other green composites. They could be used as an alternative to natural fiber-based composites for secondary load-bearing applications in various sectors like indoor, packaging, furniture, automobile interiors, etc. The addition of PSFs (30 wt.%) into the PLA matrix increased the storage modulus by 28%. A significant improvement in crystallinity was also found in these green composites. In addition, all composites up to 30 wt.% PSFs exhibited good resistance to water absorption and had a maximum water intake of 5.25%. Morphological studies revealed good adhesion and distribution of PSFs in the PLA matrix.

Effect of Air Velocity, Type and Size of Biomass on Performance of Downdraft Gasifier

Investigation on thermal gasification of different biomass materials viz., Pigeon pea stalk (Cajanus cajan),Cotton stalk (Gossypium hirsutum) and Vilaytee babool (Prosopis juliflora) in a downdraft gasifier (1 Kw capacity) was conducted to study the effect of air velocity, type and particle size of biomass. The influenceof three different particle sizes viz. 25-50, 50-75, 75-100 mm, at three different air velocities viz., 2.4, 7.4 and12.4 m s-1 on biomass consumption rate, gas flow rate and gasification yield was investigated. With theincrease in particle size, the reduction in biomass consumption rate was observed, whereas the increase inair velocity increased the biomass consumption rate. Similar trend was observed in gas flow rate andgasification yield respectively. Under the experiment conditions, the biomass consumption rate, gas flowrate and gasification yield of selected biomass material varied in the range of 3.80 to 7.76 kg h-1, 6.13 to 14.40Nm3 h-1 and 1.40 to 2.30 Nm3 kg-1, respectively. The experimental results showed that the gasificationperformance was better for Vilaytee babool (Prosopis juliflora) biomass with 25-50 mm size at 7.4 m s-1 airvelocity.

How do biochar size fractions and organic fertilizers interactively influence nitrous oxide emission from a tropical vertisol?

AbstractBackgroundNitrous oxide (N2O) emission from agriculture is increasing alarmingly due to intensive application of inorganic and organic fertilizers. Recently, biochar has been identified as a promising additive to improve agriculture by enhancing soil function and mitigate greenhouse gas emission. However, it is unclear how biochar of different size fractions influences N2O emission from agricultural soil.AimsThe current experiment aims to understand how the size of biochar (BC) and organic fertilizers interactively influence N2O emission from a tropical vertisol.MethodsBC was prepared using pigeon pea (Cajanus cajan) stalks and further processed to obtain two size fractions (<0.25 mm or 0.25–2.00 mm). Organic fertilizers (vermicompost [VC], poultry manure [PM], or farmyard manure [FYM]) and BC were added to soil to evaluate N2O emission potential. BC was added to soil at 10% (w/w), whereas the organic fertilizers were added at 80 kg N ha–1. Emission of CO2 and the abundance of 16S rRNA and amoA gene copies were estimated after incubation period. The interactive effect of BC size fractions and organic fertilizers were statistically evaluated.ResultsBoth BC and organic fertilizers stimulated N2O emission in soil. BC of larger size stimulated N2O emission (µg N2O produced g–1 soil day–1) more than smaller size. Of the three organic fertilizers, PM resulted highest N2O (0.380) emission followed by FYM (0.240) and VC (0.210). BC (0.25 mm) + PM produced least N2O. Abundance of heterotrophic bacterial 16S rRNA gene copies and ammonia‐oxidizing bacterial (AOB) amoA gene copies were highest in PM + BC and lowest in control. Significant relation (p < 0.0001) existed among N2O emission, CO2 emission, and microbial abundance.ConclusionsBC of small size fraction along with organic fertilizers can be an effective strategy to mitigate N2O emission from tropical vertisol.

INFLUENCE OF PROCESS PARAMETERS ON CELLULASE PRODUCTION BY Trichoderma viride (MTCC 800) EMPLOYING SOLID STATE FERMENTATION

In this study, the effect of physico-chemical parameters on the production of cellulase from Trichoderma viride (MTCC 800) were examined using five different agricultural residues namely banana peel, groundnut shell, corn cob, sugarcane bagasse, and pigeonpea stalk. The process parameters examined were pretreatment method, supplementation media, initial media pH, incubation period, temperature, and leaching agent. Among the parameters studied, maximum cellulase production was obtained on all the substrates treated with 1 N H2SO4 supplemented with Mandel’s medium of pH 5.5-6 after 6-8 days of incubation at 30-36°C and 0.05 M phosphate buffer (pH 7.0) as a leaching agent.

Experimental investigation on three-body abrasive wear behaviour of novel natural cellulosic pigeon pea stalk fibre reinforced epoxy biocomposites

The current research explores the possibility of reinforcing massively available, less utilised, low-cost agro-residue fibres in an epoxy matrix to create a new tribo-material. This study focuses on determining the three-body abrasive wear behaviour (volume loss and specific wear rate (SWR)) of natural cellulosic pigeon pea (PP) stalk fibre reinforced epoxy composites. Further, abrasive wear characteristics of untreated and treated E/PP20 (20 wt.% PP stalk fibre-reinforced epoxy) composites were analysed using Taguchi and ANOVA techniques. Untreated and treated biocomposite specimens were developed using the hand lay-up (open mould) technique. At 11.77 N, 23.54 N, and 47 N loads, the SWR of untreated E/PP20 composite was reduced by almost 5.03%, 3.68%, and 22.30% compared to epoxy specimens. Results of the untreated E/PP20 composite showed that the applied load was the main contributing parameter (54.72%), followed by sliding distance (21.82%) and sliding speed (15.31%). Results of the treated E/PP20 composite showed that the applied load was the main contributing parameter (48.96%), followed by sliding speed (26.24%) and sliding distance (20.78%). The regression model predicted the SWR with a pooled error ranging from 2.37% to −17.77% for untreated composite and 9.87% to −11.49% for treated composite, respectively. The alkali-treated E/PP20 composite exhibited better abrasive resistance than the untreated E/PP20 composite. Scanning electron microscopy images of the treated composites showed good fibre adhesion with the matrix. In addition, the surface of the treated composite showed no fibre pullout or ploughing compared to that of the untreated composite. Surface topography revealed the formation of more craters on the surfaces of the untreated composites and small-sized dispersed craters on the treated composites.

Characterization of Biochar Derived from Crop Residues for Soil Amendment, Carbon Sequestration and Energy Use

The crop residues generated in agricultural fields are mostly considered a burden due to their disposal issues. This study attempts to effectively use pigeon pea stalk (PPS) for biochar production, a promising source as a soil amendment for carbon sequestration and alternative fuel source. PPS was pyrolyzed at different loads and reaction times to optimize the kiln temperature (350–400 °C and 450–500 °C) and changes in physicochemical properties, higher heating value (HHV) and yield were assessed. The results indicated that biochar yield, volatile matter, bulk density, O/C and H/C atomic ratios decreased, whereas fixed carbon, ash content and total porosity increased with increasing kiln temperature across all loads. Biochar produced at 450–500 °C (18 kg load kiln−1) had higher total carbon, nitrogen, phosphorous, recovered total carbon and total nitrogen, total potential carbon and CO2 reduction potential. Biochar produced at 350–400 °C had the maximum cation exchange capability (43.0 cmol kg−1). Biochar has estimated O/C and H/C atomic ratios of 0.07–0.15 and 0.35–0.50, respectively. Biochar exhibited good agronomic characteristics and fulfilled key quality criteria of H/C < 0.7 and O/C < 0.4 for soil carbon sequestration, as described by the European Biochar Certificate and the International Biochar Initiative. The estimated mean residence time and the mass fraction of carbon that would remain after 100 years were consistently greater than 1000 years and 80%, respectively. The biochar produced at 450–500 °C (at 18.0 kg kiln−1) from PPS had higher fixed carbon (65.3%), energy density (1.51), energetic retention efficiency (53%), fuel ratio (4.88), and HHV (25.01 MJ kg−1), as well as lower H/C and O/C ratios, implying that it is suitable for use as an alternative solid fuel.