Agricultural Waste Biomass Research Articles

Enhancing Sustainable Production of Biodiesel from Xanthoceras sorbifolia Bunge Oil Using Bio-Based Heterogeneous Catalyst

The swift exhaustion of natural oil reserves and worsening environmental issues have prompted the quest for an economical method to produce biofuels. The superiority of heterogeneous catalysis promotes the development of bio-based catalysts. Carbon materials prepared from agricultural and forestry biomass waste have good application prospects in catalysis. In the present study, Xanthoceras sorbifolia shell waste was used as the raw material, Xanthoceras sorbifolia Bunge Carbon (XC) was used as the catalyst carrier, and K2CO3 was used as the activator to prepare a heterogeneous catalyst (KXC). The heterogeneous catalyst was characterized by scanning electron microscopy-energy dispersion X-ray spectroscopy (SEM-EDS), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and Brunauer–Emmett–Teller (BET) and X-ray photoelectron spectroscopy (XPS) analysis techniques to evaluate its chemical composition, structure, and physical morphology. EDS and XPS revealed the presence of K metal, which provided an alkaline site for the transesterification reaction to produce biodiesel. The biodiesel yield was observed by gas chromatography−mass spectrometry (GCMS). Under the reaction conditions of a methanol-to-oil molar ratio of 12:1, a reaction time of 90 min, a temperature of 65 °C, and a catalyst loading of 4 wt.% using 25KXC-600-4, the yield of biodiesel can reach 95.13 ± 0.82%. After being repeated five times, the yield was still 58.11 ± 3.80%. The catalyst has no waste generation, and has the characteristics of simple preparation and environmental friendliness, which make it a green heterogeneous catalyst for biodiesel production.

Effect of Biomass Burnings on Population Exposure and Health Impact at the End of 2019 Dry Season in Southeast Asia

At the end of the dry season, from early March to early April each year, extensive agricultural biomass waste burnings occur throughout insular mainland Southeast Asia. During this biomass-burning period, smoke aerosols blanketed the whole region and were transported and dispersed by predominant westerly and southwesterly winds to southern China, Taiwan, and as far southern Japan and the Philippines. The extensive and intense burnings coincided with some wildfires in the forests due to high temperatures, making the region one of the global hot spots of biomass fires. In this study, we focus on the effect of pollutants emitted from biomass burnings in March 2019 at the height of the burning period on the exposed population and their health impact. The Weather Research Forecast-Chemistry (WRF-Chem) model was used to predict the PM2.5 concentration over the simulating domain, and health impacts were then assessed on the exposed population in the four countries of Southeast Asia, namely Thailand, Laos, Cambodia, and Vietnam. Using the health impact based on log-linear concentration-response function and Integrated Exposure Response (IER), the results show that at the peak period of the burnings from 13 to 20 March 2019, Thailand experienced the highest impact, with an estimated 2170 premature deaths. Laos, Vietnam, and Cambodia followed, with estimated mortalities of 277, 565, and 315 deaths, respectively. However, when considering the impact per head of population, Laos exhibited the highest impact, followed by Thailand, Cambodia, and Vietnam. The results highlight the significant health impact of agricultural waste burnings in Southeast Asia at the end of the dry season. Hence, policymakers should take these into account to design measures to reduce the negative impact of widespread burnings on the exposed population in the region.

Processing wheat straw into a near-infrared light selective transmission film

This research focuses on the development of near-infrared light selective transmission film (NIR-LSTF) utilizing wheat straw biomass, extracting lignocellulose and lignin through the acetic acid method. Employing a hydrogel-based approach, lignin was encapsulated and underwent self-assembly both within and atop the hydrogel, enabling initial integration with cellulose. Hot pressing facilitated the thorough amalgamation of lignin into the cellulose matrix, enhancing the NIR-LSTF's resistance to environmental wear and creating a dense structure that minimizes light loss and reflection, thus outperforming traditional materials in optical efficiency and functionality. Moreover, the presence of lignin imparts the material with unique selective absorption characteristics, effectively blocking nearly all ultraviolet light and visible light (approximately 100 % at 610 nm and 78 % at 780 nm), while maintaining a high transmittance rate (∼90 %) in the near-infrared spectrum. This property underscores the films' significant potential in applications demanding near-infrared transparency. The efficacy of NIR-LSTF in the realms of infrared surveillance and privacy protection was assessed, yielding favorable experimental outcomes. This study paves a new pathway for the valorization of agricultural waste biomass within the near-infrared optical domain.

Transformation of Agriculture Waste Biomass to Sustainable and Slow Release Fertilizers: Waste to Wealth

Transformation of Agriculture Waste Biomass to Sustainable and Slow Release Fertilizers: Waste to Wealth

A Comprehensive Review of Lab-Scale Studies on Removing Hexavalent Chromium from Aqueous Solutions by Using Unmodified and Modified Waste Biomass as Adsorbents.

Anthropogenic activities and increasing human population has led to one of the major global problems of heavy metal contamination in ecosystems and to the generation of a huge amount of waste material biomass. Hexavalent chromium [Cr(VI)] is the major contaminant introduced by various industrial effluents and activities into the ecosystem. Cr(VI) is a known mutagen and carcinogen with numerous detrimental effects on the health of humans, plants, and animals, jeopardizing the balance of ecosystems. Therefore, the remediation of such a hazardous toxic metal pollutant from the environment is necessary. Various physical and chemical methods are available for the sequestration of toxic metals. However, adsorption is recognized as a more efficient technology for Cr(VI) remediation. Adsorption by utilizing waste material biomass as adsorbents is a sustainable approach in remediating hazardous pollutants, thus serving the dual purpose of remediating Cr(VI) and exploiting waste material biomass in an eco- friendly manner. Agricultural biomass, industrial residues, forest residues, and food waste are the primary waste material biomass that could be employed, with different strategies, for the efficient sequestration of toxic Cr(VI). This review focuses on the use of diverse waste biomass, such as industrial and agricultural by-products, for the effective remediation of Cr(VI) from aqueous solutions. The review also focuses on the operational conditions that improve Cr(VI) remediation, describes the efficacy of various biomass materials and modifications, and assesses the general sustainability of these approaches to reducing Cr(VI) pollution.

A pilot study on a 30 t/h biomass gasification-combustion plant

As a renewable energy with zero carbon emission, the utilization of biomass has attracted widely studied. One of the most effective methods is to gasify the biomass into high-quality gas fuel. In the recent years, the majority of research on biomass gasification is conducted in the laboratory. However, it lacks the research in engineering application scale. In this work, a biomass gasification-combustion plant was designed and built to provide the industrial steam with a rate of 30 t/h for a food industrial park. The agricultural and forestry waste biomass was gasified in a gasifier, and then the product gas combusted in a boiler to supply the steam. The characteristics of the product gas from the gasifier were studied. The corrosion and pollutants in the combustion process were investigated. In the gasification process, the main components of the product gas are CO, H2 and CH4. CO and H2 account for 29.55 vol%-30.56 vol% and 11.65 vol%-15.35 vol%, respectively. The calorific value of the product gas is 5.88–6.29 MJ/m3. The tar concentration is 110.58–155.07 g/Nm3. At the outlet of the boiler, the concentration of the filterable particulate matter is 300.25 mg/Nm3, and the particle size is concentrated at 1.00–2.50 μm. The concentration of the condensable particulate matter (CPM) is 157.14 mg/Nm3, and the proportion of water-soluble ions in CPM is 86.36 wt%. The concentration of Cl−, SO42-, NH4+ and Na+ in CPM is relatively high, with the values of 28.83 mg/Nm3, 10.29 mg/Nm3, 7.46 mg/Nm3, and 5.06 mg/Nm3, respectively. During the half-year running, the ash deposition and corrosion were detected in the boiler heating surface and the economizer. The ash deposit in the boiler is mainly composed of the sulfate and silicate, such as CaSO4, Zn2SO4, Na2SO4 and K3Na(SO4)2. The ash deposit in the economizer is primarily composed of the sulfate and a small amount of alkali metal chloride. The flue gas reaches the emission requirement after passing through the pollution control devices and can be discharged into the atmosphere.

Porous carbon derived from center part of the corn cob for high-performance symmetrical supercapacitors

The central part of agricultural waste biomass corn cob was used as carbon precursor and KHCO3 as activating agent, and porous carbon materials were prepared by one-step carbonization method. The effect of KHCO3 on the structure and properties of porous carbon was studied. The results show that KHCO3 has an etching effect on porous carbon, and the greater the amount of KHCO3, the stronger the etching effect. The obtained biomass porous carbon material has abundant pores, reasonable pore size distribution and high specific surface area, which is conducive to ion transfer and charge storage. In addition, the heteroatom self-doping of porous carbon can improve surface hydrophilicity and generate additional pseudocapacitance, thereby improving its electrochemical properties. Electrochemical characterization shows that the porous carbon has a specific capacitor of up to 323 F g−1. The assembled symmetric supercapacitor (SSC) has an energy density of 20 Wh kg−1 at a power density of 350 W kg−1. This low-cost, high-performance electrode material has potential applications in high-power supercapacitors.

Reduction and Reuse of Forestry and Agricultural Bio-Waste through Innovative Green Utilization Approaches: A Review

Biomass waste, which is biodegradable and vastly underutilized, is generated in huge quantities worldwide. Forestry and agricultural biomass wastes are notable for their wide availability, high yield, biodegradability, and recyclability. The accumulation of these wastes not only occupies valuable land but causes serious environmental pollution, which can ultimately harm human health. Therefore, leveraging scientific technology to convert forestry and agricultural bio-waste into bioenergy and other valuable products is crucial. In this paper, common forestry and agricultural bio-waste such as straw, rice husks, livestock manure, tree branches, sawdust, and bioenergy (bioethanol, biogas, biodiesel, biohydrogen) were selected as keywords, with the theme of green and efficient utilization. This paper provides a comprehensive review of the sources of biomass waste, existing recycling technologies, and the potential of forestry and agricultural bio-waste as material additives and for conversion to biomass energy and other derivatives, along with future recycling prospects.

Enhancing herbicide adsorption in low-fertility soil using sugarcane biochar: Insights from Imazapic dynamics

Biochar amendment has emerged as a potential solution for preventing, remediating, and mitigating agricultural compound pollution. This groundbreaking technique not only improves crucial soil properties like porosity, water retention capacity, cation exchange capacity, and pH, but also intricately impacts the interaction and retention mechanisms of polluting molecules. In this study, we investigate the dynamic of the herbicide Imazapic when subjected to applying pyrolyzed biochars, specifically at temperatures of 300 and 500 °C, within the context of a low-fertility soil characterized as dystrophic Yellow Ultisol (YUd) in a sugarcane cultivation area in Igarassu-PE, Brazil. The biochars were produced from sugarcane bagasse by pyrolysis process in a muffle furnace. In laboratory conditions, with saturated soil columns under steady-state, analyses of the mechanisms involved in interaction and transport and determining hydrodispersive parameters for Imazapic were performed by the two-site nonequilibrium transport model using the CXTFIT 2.0 program. Samples of YUd soil amended with biochar pyrolyzed at 300 °C presented a negligible interaction with Imazapic. However, adding biochar pyrolyzed at 500 °C (BC500) to the soil samples enhanced the adsorption coefficient and improved the interaction with Imazapic. This research points out that biochar produced from agricultural waste biomass, such as sugarcane bagasse specifically pyrolyzed at 500 °C, offers a potential means to adsorb herbicides, reducing their leaching to deeper layers of the amended soils and the risk of groundwater contamination and potential environmental negative impacts.

Mesoporous carbon particles by biomass waste based on sulfonation and copper oxide functionalization as efficient and stable electrode material for supercapacitor.

Here, the hierarchical mesoporous-activated carbon particles obtained by KOH activation from pistachio shell wastes are modified by both the sulfonation process and CuO doping by hydrothermal heating (CuO@S-doped PSAC) for use as a supercapacitor. It is predicted that the electrochemical performance of the porous carbon electrode material obtained by such CuO doping and sulfonation process will be significantly increased with increased Faradaic capacitance. The electrochemical performance of CuO@S doped PSAC composite is systematically investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and galvanostatic charge/discharge (GCD) in the presence of 1M H2SO4, 1M Na2SO4, and 1M NaOH as electrolytes. The CuO@S doped PSAC-based electrode shows excellent stability with high specific capacitance up to 397.16 F/g at 0.1 A/g and 92.64% retention. Furthermore, FTIR, SEM, XRD, EDS, and nitrogen adsorption/desorption analyses are used for the characterisation of the obtained composites. Based on a significant supercapacitor performance, the synthesis strategy of carbon-based electrode material containing sulfonation and CuO modifications derived from agricultural biomass waste material is predicted to be a valuable example.

Alkaline pretreatment of Durio sp. residual biomass enhances cellulose accessibility for efficient bioethanol production

The reliance on fossil fuels for energy generation has led to significant environmental, social, and economic challenges, necessitating the exploration of sustainable alternatives. Bioethanol, derived from renewable sources such as agricultural waste, presents a promising substitute. This study investigates the potential of durian skin, an abundant agricultural byproduct, as a raw material for bioethanol production. Alkaline pretreatment using NaOH significantly altered the chemical composition and structural properties of durian skin, increasing cellulose content and removing lignin. The cellulose content of the outer durian skin (ODS) and deep durian skin (DDS) increased by 57.53% and 59.28%, respectively, after pretreatment. The X-ray diffraction and Fourier transform infrared spectroscopy of cellulose and lignin provide significant information. Using 30 FPU enzymes to load the substrate results in DDS producing 126 g/L of glucose and 42.8 g/L of ethanol. The optimal conditions are 15% NaOH pretreatment, 150 °C, 4 bars pressure, and 90 min. The study demonstrates the economic viability and environmental benefits of utilising durian skin for bioethanol production, offering insights into sustainable energy sources and waste valorisation. These findings contribute to the global shift towards renewable energy and highlight the importance of pretreatment in enhancing bioethanol production efficiency from agricultural biomass waste.

Green iron and syngas production via continuous solar-driven agricultural waste biomass gasification combined with iron(III) oxide reduction

The production of renewable synthetic fuels and chemicals from solar energy and agricultural waste biomass is considered. Solar thermochemical conversion processes offer a promising pathway to a sustainable fuel economy and green chemical industry. This study investigates the continuous solar-driven gasification of agricultural biomass (betel nut waste) combined with iron oxide (Fe2O3) reduction to produce carbon-neutral syngas and green metallic iron in a single process. A thermodynamic analysis of the system was initially conducted to predict the distribution of equilibrium products. Then, on-sun continuous processing was experimentally carried out under different operating conditions, including betel/Fe2O3 molar ratios (0.56–1.5) and temperatures (900–1200 °C) to evaluate the process feasibility and reliability. As a result, solar gasification of betel nut waste combined with Fe2O3 reduction performed exceptionally well with continuous reactant particles feeding, demonstrating a feasible pathway for producing green iron and high-quality syngas. The maximum syngas yield reached 63.3 mmol/gdry_betel, approaching its theoretical value, and high-purity Fe was simultaneously produced. The process demonstrated high efficiency, with maximum carbon conversion approaching 98 %, energy upgrade factor up to 1.26, and solar-to-fuel energy conversion efficiency up to 14.4 %, highlighting remarkable conversion performance of biomass and solar energy to chemicals.

Research Progress of Functional Materials for Conversion of Agricultural Biomass Wastes

Excess agricultural biomass waste is increasing rapidly, leading to many environmental and governance issues. Therefore, increased attention has been paid to the recycling and value-added application of agricultural biomass waste. In recent years, the research of agricultural biomass waste utilization and derived functional materials has mainly included the following two aspects： ① the extraction of natural polymers and value-added applications and ② the direct preparation of new carbon-based materials, including adsorption, catalysis, energy storage electrode, and composite functional materials. The conversion of agricultural biomass waste into functional materials has been gradually realized and widely used. To enable industrial-scale production and the quality and safety of agricultural biomass waste derivatives and to develop highly feasible and cost-effective biomass waste conversion methods should be the focus of future studies.

Compositional Analysis of the Lignocellulosic Biomass from Agricultural Waste (Rice Husk)

Rice husk, a byproduct of rice milling, represents a significant agricultural waste biomass with untapped potential for various industrial applications. This study provides a comprehensive compositional analysis of rice husk to explore its utility as a valuable resource. The chemical composition of rice husk such as initial moisture content, hemicellulose, cellulose, lignin, ash and extractives were analyzed. The result reported in mean value i.e 9.884 ±0.56 (%) moisture content, 8.077±0.27 (%) extractives, 17.210 ± 0.69 (%) lignin, 21.073 ± 0.62 (%) hemicellulose and 38.640 ± 0.94 (%) cellulose, 15.0 ±0.87 (%) ash. This study concludes that rice husk is an abundant source of cellulose and holds significant potential for cellulose isolation.

Valorization of lignocellulosic biomass: Progress in the production of second-generation bioethanol

Cellulosic ethanol, a biofuel product derived from microbial fermentation of cellulose-rich agricultural waste biomass, holds the potential to significantly contribute to sustainable development, energy security, and environmental friendliness as a green and renewable alternative energy source. Cellulosic ethanol offers remarkable energy benefits and carbon emission reductions. However, the biorefining process of cellulosic ethanol faces challenges and complexities. This article revolves around five aspects: feedstock, composition, pretreatment, cellulase hydrolysis, and ethanol fermentation processes in the biorefining of cellulosic ethanol. It provides an overview of the process flow and characteristics of cellulosic ethanol biorefining, emphasizing its significance. The main technological bottlenecks in cellulosic ethanol production are analyzed. Recent research advancements in cellulosic ethanol biorefining are summarized, followed by an outlook on the research focus and future prospects in the field of cellulosic ethanol.

Conversion of Waste Agricultural Biomass from Straw into Useful Bioproducts—Wheat Fibers and Biofuels

Straw, the primary agricultural waste, constitutes approximately 20% of the total biomass in the EU. Only a small fraction of the material is applied in various products, e.g., animal bedding, mulch, building, and composite materials, while a significantly larger portion is often burned in the field. This practice, while prohibited for several reasons, including the increased risk of fire and the release of carbon dioxide contributing to global warming, is still prevalent. Given the increasingly evident effects of climate change, EU legislation aims to reduce greenhouse gas emissions as much as possible. One of the strategies includes applying the cascade principle in the circular economy. This principle aims to use the entire raw material, in this case, cereal crops, such that the products with the highest added value, like cellulose fibers from cereal straw, are extracted first. The vast potential for utilizing lignocellulosic agro-waste sustainably arises from its status as the most abundant organic compound on Earth. Its significant presence, renewability, and biodegradability make it a desirable source for producing materials in numerous industries. This study examines the potential of wheat fibers, isolated from the straw of two distinct cultivars (Srpanjka represents an old variety, and Kraljica represents the new variety) primarily for application in technical textiles. The following testing methods were applied: determination of wheat fibers and residues yield, fibers tensile properties, length, moisture content/regain, density, morphology, and Fourier transform infrared (FTIR) spectroscopy. The yield of isolated fibers relies on the wheat variety and the climatic conditions affecting plant growth, resulting in fiber yields from 10.91% to 15.34%. Fourier transform infrared (FTIR) analysis indicates reduced peak intensity, which is related to hemicellulose and lignin content, suggesting their improved deposition following the process of chemical maceration. Wheat fiber quality was found to be comparable to cotton fibers regarding its density. However, they showed a significant difference in higher moisture regain (9.72–11.40%). The vast majority of the scientific papers related to wheat fibers did not indicate the length of the individual fibers obtained by chemical maceration nor their strength. Therefore, this paper indicated that both varieties demonstrated sufficient fiber tenacity (greater than 10 cN/tex) and fiber length (2–3 cm), stressing the spinning potential of these fibers into yarns and extending their use to the apparel industry. Moreover, our research underscores the feasibility of adhering to the zero-waste principle. A high percentage of solid waste remaining after fiber extraction (25.3–39.5%) was successfully used for biofuel production, thus closing the loop in the circular economy.

Co-hydrothermal conversion of kitchen waste and agricultural solid waste biomass components by simple mixture: study based on bio-oil yield and composition

The co-hydrothermal conversion of kitchen waste and lignocellulosic biomass solid waste into bio-oil holds the potential to revolutionize the production of multi-source biomass hydrothermal bio-oil. In this study, the interaction between kitchen waste and agricultural solid waste during the hydrothermal conversion process was investigated, focusing on the yield and properties of the resulting bio-oil, the obtained bio-oil was characterized. Results reveal that the Maillard reaction plays a pivotal role in influencing the production of hydrothermal bio-oil during the co-hydrothermal conversion process. Proteins and amino acids, in particular, exhibit a strong promotional effect on the generation of hydrothermal bio-oil. The introduction of kitchen waste did not significantly change the chemical and elemental composition of the bio-oil derived from agricultural solid waste. However, the specific content of compounds within the hydrothermal bio-oil varied widely. When compared to single-component hydrothermal bio-oils derived from lignin, cellulose, and hemicellulose respectively, the addition of kitchen waste resulted in a notable enhancement of the bio-oil's overall calorific value and a reduction in its oxygen content. The findings of this study have the potential to pave the way for sustainable and economically viable processes for multi-source biomass hydrothermal bio-oil preparation.

Cold plasma‐assisted extraction of anthocyanin from purple corncobs and its antioxidant activity

AbstractIn this study, a novel radio‐frequency cold plasma‐assisted extraction (CPAE) process was developed for the extraction of anthocyanins from a type of agricultural biomass waste, purple corncob. The effects of cold plasma pretreatment on anthocyanin extraction were investigated, and this process was further optimized using response surface methodology. The components of purple corncob anthocyanins (PCAs) were analyzed by super‐high performance liquid chromatography‐mass spectrum. The antioxidant activity of PCAs was evaluated through 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) and 2′‐azinobis‐(3‐ethylbenzthiazoline‐6‐sulfonate) (ABTS) scavenging capacity assays in vitro and physiological behaviors in vivo for Caenorhabditis elegans. The results showed that the optimal conditions of cold plasma pretreatment were discharge power 127 W, working pressure 150 Pa, and the treatment time 75 s. The maximum yield of PCAs was about 4.05 ± 0.05 mg/g corncob, much higher than that of the conventional solvent extraction and ultrasonic‐assisted extraction. PCAs were mainly composed of pelargonidin‐3‐galactoside (66.02 wt.%), cyanidin‐3‐galactoside (25.95 wt.%), cyanidin (8.02 wt.%), and petunidin‐3‐galactoside (0.02 wt.%). The extracted anthocyanins reflected the superior antioxidant activity. In terms of in vitro antioxidant ability, the half maximal inhibitory concentration (IC50) of PCAs for DPPH and ABTS were slightly lower than those of ascorbic acid. Meanwhile, C. elegans exhibited positive effects on several physiological behaviors by feeding PCAs, including a 29.25% increase in lifespan, and increases in antioxidant capacity, superoxide dismutase, and catalase (CAT) activity of 26.28%, 28.93%, and 22.24%, respectively. The CPAE process is therefore a highly competitive candidate for the realization of industrial PCAs extraction, combining some additional advantages of cold plasma treatment such as green process, low cost, short treatment time, and scale‐up production.Practical applicationsAgricultural biomass wastes (e.g., corncob, straws, and husks) contain a large number of high value‐added natural active ingredients (e.g., polysaccharides, anthocyanins, and polyphenols). However, a highly efficient extraction of these natural active ingredients is always sought, as the protection of lignocellulosic cell walls hinders the extraction of intracellular products. In this work, the cold plasma‐assisted extraction (CPAE) process showed a comparatively higher anthocyanin yield than the conventional solvent extraction and ultrasonic‐assisted extraction processes. This was due to the fact that the high‐energy helium plasma attack readily broke down the lignocellulosic structure of the plant cell walls, resulting in the rapid release of intracellular purple corncob anthocyanins into the extraction medium. This study suggests that the CPAE process will become an emerging application for the industrial extraction of high value‐added natural active ingredients from agricultural biomass wastes.

Agricultural Waste Valorization: Exploring Environmentally Friendly Approaches to Bioenergy Conversion

The pursuit of sustainable energy production through the conversion of agricultural waste into different bioenergy resources is of paramount importance given its potential to mitigate environmental impact while meeting energy demands. In this review, a comprehensive overview of the technologies for the biochemical and thermochemical conversion of agricultural waste into bioenergy is provided. A summary of the process of its conversion into different bioenergy products such as biogas, bio-oil, and biofuel is provided, in addition to the potential advantages and challenges faced using different biomass conversion technologies. The review highlights the potential of agricultural waste valorization to address the current energy demand while at the same time contributing to environmental benefits and greenhouse gas emission reductions. Moreover, this review highlights some significant gaps for improvement. These include the challenges in the pretreatment of agricultural waste biomass in optimizing the conversion rates and lowering the required energy consumption throughout the process while enhancing both the quantity and quality of the output. Some recommendations are proposed to address the identified challenges. These include the need for further studies for a thorough assessment to evaluate the efficacity and sustainability of agricultural waste valorization technologies. Assessment methods such as life cycle assessment (LCA), life cycle analysis (LCA), net energy ratio (NER) calculations, life cycle costing (LCC), as well as techno-economic assessment (TEA), are recommended, together with collaboration among governments, farmers, and researchers, as well as the integration of cutting-edge technologies to enhance various aspects of agricultural waste, optimizing the conversion process, cost efficiency, time management, and labor requirements, consequently boosting the conversion efficiency and product quality.

Investigation of regeneration cycles with different catalysts on steam gasification of biomass

In this work, agricultural biomass waste was gasified in a two-zone tubular reactor in the presence of steam. Firstly, during preliminary experiments the effect of temperature in the 1st and 2nd reactor zone, as well as the influence of catalysts and steam/raw material ratio was investigated, then the reusability of catalysts was also studied during ten regeneration cycles. Based on the preliminary results, in the 1st reactor zone a lower temperature was used (400 °C), where the yield of carbon dioxide was ∼55 %, which has a positive effect on numerous reactions, also it can be converted to carbon monoxide with proper catalysts with in-situ process. Regarding the temperature, it is important to be mentioned that a significant difference was observed in the yield of synthesis gas at 700 °C thus, the experiments were carried out using 700 °C in the 2nd reactor zone. A natural (Clinoptilolite) and a synthetic zeolite (ZSM-5), a mesoporous alumina (Al2O3) and a carbon dioxide capturing carrier (CaO) were selected and impregnated with nickel for further use and for enhancing the yield of synthesis gas and hydrogen during the gasification process. The utilization of catalysts helped the in-situ reduction of carbon dioxide while their performance in the gasification process during the regeneration cycles was also investigated. Henceforward, the tested Ni/ZSM-5, Ni/Al2O3 and Ni/Clinoptilolite, reduced the amount of carbon monoxide from the 5th regeneration cycles, while the amount carbon dioxide with the four mentioned catalysts was decreased by 15–35 mmol/g raw material, compared to the results obtained during thermal degradation.