Almond Shell Research Articles

Assessment of the use of biochar from the slow pyrolysis of walnut and almond shells as an energy carrier

ABSTRACT This study explores the energy applications and combustion kinetics of biochar produced from walnut and almond shells through pyrolysis. Using macro-thermogravimetric analysis at heating rates of 10, 15, and 20 K min−1, a multi-step mechanism involving two parallel reactions was used to model thermal decomposition. Bioenergy indices revealed that walnut shell-based biochar (WSB) produced at 773 K and 873 K displayed superior biofuel potential due to its high energy density and low ash content, while almond shell-based biochar (ASB) at 673 K demonstrated the best overall bioenergy performance. Among the tested heating rates, 15 K min−1 provided optimal results for ignition, combustion, and burnout indices, with WSB showing the highest overall combustion performance. Kinetic analysis using the Coats-Redfern method demonstrated the highest R2 values and minimized RMSE and SSE. The activation energy for the first pseudo-component ranged from 54.91 to 129.84 kJ mol−1 for ASB and from 61.71 to 141.85 kJ mol−1 for WSB. For the second pseudo-component, the activation energy ranged from 25.21 to 159.32 kJ mol−1 for ASB and 25.63 to 96.25 kJ mol−1 for WSB. These findings emphasize the potential of WSB and ASB biochar for bioenergy applications, with WSB exhibiting the best combustion characteristics.

Optimizing catalytic performance: Reduction of organic dyes using synthesized Fe3O4@AC magnetic nano-catalyst

This article presents a sustainable method for the catalytic reduction of both simple and binary dye systems using magnetic activated carbon (Fe3O4@AC) synthesized from almond shells, an agricultural waste biomass. The reduction of methylene blue (MB) and Congo red (CR) was investigated in the presence of NaBH4, and a series of physical-chemical experiments were conducted to elucidate the mechanism of dye conversion and its performance. The results confirmed the successful synthesis of Fe3O4 nanoparticles on the activated carbon surface. The calculated rate constants in a simple system were 0.34 min⁻1 for MB and 0.25 min⁻1 for CR, in the binary system, the Fe3O4@AC catalyst demonstrated enhanced selectivity for the cationic MB dye, attributable to the robust, attractive surface charge. The study aimed to enhance catalytic performance by employing optimization curves generated from a three-level Box-Behnken Design (BBD) simulation. Experimental results indicated that the optimal catalyst dose, dye concentration, and reaction duration were 4–7 mg, 80–120 mg/L, and 5–20 min, respectively. Response surface methodology (RSM) was developed by processing the findings from 17 replicated experiments using a two-quadratic polynomial model, establishing a functional link between the experimental parameters and MB conversion. Optimal conditions for MB conversion were determined to be 7 mg of catalyst, 80 mg/L of MB concentration, and a reaction time of 12.5 minutes, resulting in an estimated conversion rate of 99.99 %. This prediction was validated by experimental findings, with regression analysis confirming a high correlation (R2 > 0.99) between the predicted and observed values. Additionally, the Fe3O4@AC catalyst demonstrated good recyclability and stable performance over three consecutive cycles, maintaining high conversion efficiency without loss of performance. These findings demonstrate that Fe3O4@AC is a viable approach for the rapid and efficient remediation of dyes in water.

Can hydrogen be generated by UV- photodegradation of biomass residues in water media?

The photoinduced processes can be promising routes for hydrogen generation. This study explores hydrogen production through the non-catalyzed photodegradation of various biomass materials, a process that remains largely understudied compared to the catalyzed ones, i.e., photoreforming. Using as precursor almond shell (AS), a lignocellulosic biomass residue, various solid and liquid materials obtained from it were tested as substrates. These materials were obtained through different pretreatment methods including grinding, milling, pyrolysis, and hydrothermal carbonization (HTC), and compared with milled cellulose (MC). Photodegradation tests, conducted in aqueous media under UV light, revealed that hydrogen production strongly depends on the structural and compositional features of the substrates. Among the solid samples, ground almond shell (GAS) and milled cellulose (MC) showed promising hydrogen yields. However, the liquid residue from the HTC process using diluted phosphoric acid (HMAS-L2), which is rich in simple organic acids, stood out, delivering the highest hydrogen production across all the substrates, and reaching an impressive value of 105 μmol of H2 in 5 h of reaction. Attention was also given to the production of other gases, particularly carbon dioxide and methane, as a result of the photodegradation. CO2 production occurred for all the substrates. PMAS (the pyrolyzed milled almond shell) and, specifically, HMAS-L2 generated detectable amounts of CH4 (5 and 22 μmol, respectively).The H2/CO2 ratios reached 0.66 for MC and 0.44 for HMAS-L2, highlighting the interest in evaluating the non-catalyzed biomass photodegradation as a preliminary step for future photoreforming studies. These findings enhance our understanding of biomass-based hydrogen generation and open new avenues for exploring non-catalyzed photoinduced processes.

Phytotoxicity Assessment of Agro-Industrial Waste and Its Biochar: Germination Bioassay in Four Horticultural Species

This study investigated the phytotoxicity of agro-industrial wastes (almond, walnut, pistachio and peanut shells, asparagus spears, and brewer’s spent grain) and their biochar through germination bioassays in several horticultural species: green pea, lettuce, radish, and arugula. Biowaste was pyrolyzed under controlled conditions to produce biochar, and both biowaste and biochar were characterized. Germination bioassay was conducted using seeds exposed to different dilutions of aqueous extract of biowaste and their biochar (0, 50, and 100%). Germination percentage, seed vigor, germination index, and root and aerial lengths were evaluated. The results showed that the phytotoxicity of the biowaste was significantly different to that of its biochar. The biochar obtained demonstrated changing effects on germination and seedling growth. In particular, biochar extracts from spent brewers grains, walnut shells, and pistachio shells showed 5–14% increases in seed vigor and root and aerial length. Furthermore, the response of different species to both agro-industrial waste and biochar revealed species-specific sensitivity. Seeds of lettuce and arugula species were more sensitive to aqueous extracts than radish and green peas. This knowledge not only elucidates the behavior of agro-industrial waste-based biochar in the early stage of plant development but also provides valuable insights regarding phytotoxicity, seed sensitivity, and the variables involved in germination.

Simultaneous removal of Pb(II) and Cr(VI) from a steel company wastewater using various green adsorbents: Material characterization and numerical optimization

ABSTRACT This study focuses on the simultaneous uptake of Pb(II) and Cr(VI) from industrial wastewater by walnut shell (WS), almond shell (AS), peanut shell (PS), and coconut shell (CS) adsorbents. Among the used adsorbents, the CS adsorbent exhibited the greatest BET surface area of 18.97 m2/g and porosity of 63.17% and the WS adsorbent also had the highest pore volume of 0.3536 m3/g. Lead and chromium removal were optimized using response surface methodology via a central composite design (CCD) approach. The efficiency of lead and chromium uptake from the wastewater was enhanced by increasing the concentration of WS, AS, PS, and CS adsorbents (Cads.) and decreasing the flow rate (Q) of the wastewater. Under the optimal conditions (Cads. = 0.85 g/L and Q = 2.5 mL/min), the maximum lead and chromium uptake from steel company wastewater was achieved using CS (92%) and WS (97.2%) adsorbents, respectively. The actual lead and chromium removal values were well-fitted based on a high Rpred2, confirming the validity of the CCD model. The acceptable performance of these green adsorbents in the simultaneous removal of chromium and lead from the wastewater introduces the WS, AS, PS, and CS adsorbents as inexpensive and available candidates for industrial wastewater treatment containing heavy metals.

Almond Hulls and Shells Extract Characterized as a High-Performance Eco-Friendly Antioxidant and Corrosion Inhibitor

Almond Hulls and Shells Extract Characterized as a High-Performance Eco-Friendly Antioxidant and Corrosion Inhibitor

Development of Composite Adsorptive Biosorbent from \(H_3PO_4-NaOH-BaCl_2\) Modified Almond Shell: Experimental and Statistical Approach

This study aimed to use an experimental and statistical approach to develop a cost-effective composite adsorptive biosorbent from acid, base and salt-modified biomass. Almond Shell samples were washed, milled to uniform particle sizes (425 µm) and then modified with H3PO4, NaOH, and BaCl2 separately. The three active samples were combined to form a tricomposite biosorbent based on the Simple Lattice Design (SLD) under the Mixture Methodology of the Design Expert Software (11.0.1), within the ranges of 20-60%. The adsorptive capacity of each within tricomposite consisting of different percentage compositions of the modified Almond shell samples was investigated based on the Methylene Blue Number (MBN) Test. The results obtained were subjected to statistical analysis. The maximum adsorption capacity (MBN) of 896.12 mg/g was obtained from the tricomposite almond shell comprising mixture ratio of 20% (H3PO4), 20% (NaOH) and 60% BaCl2. The combination is well fitted to Linear Model () with Std. Dev. of 13.25, R² of 0.6452, Adjusted R² of 0.5565, Predicted R² of 0.4566 and Adeq Precision of 8.472 (>4). The numerical optimization of the experimental data was obtained at 0.980 desirability. The experimental values obtained were in good agreement with the predicted values from the models, with relatively small errors (0.13%) between the predicted and the actual values. This shows that the optimisation process via the SLD was very fit and reliable.

Recovery of Phosphate From Aqueous Solution by Mg/Ca-Modified Biochar Derived From Dewatered Dry Sludge and Waste Almond Shells and Its Potential Application

Recovery of Phosphate From Aqueous Solution by Mg/Ca-Modified Biochar Derived From Dewatered Dry Sludge and Waste Almond Shells and Its Potential Application

Utilizing almond shell filler to improve strength and sustainability of jute fiber composites

AbstractIn recent years, natural fibers have begun to replace synthetic fibers in automotive, building, and marine applications because of their sustainability, renewability, low cost, and availability of raw materials. However, because of their low strength, biocomposites are strengthened by hybridization with stronger synthetic fibers or adding fillers. This study reinforced high‐cellulose jute fiber composites with cellulose‐based almond (Prunus amygdalus) shell filler (ASF). Natural waste almond shells were ground to microparticle size. Hybrid composites were prepared by adding microparticulate ASF to the jute fiber composites at 0%, 1.5%, 3%, 4.5%, and 6% by weight. A comprehensive experimental study included tensile, flexural, Charpy impact (flat and edgewise), and shear tests. The addition of ASF significantly improved the mechanical properties of the jute fiber composites, and the best values were obtained with 3 wt.% ASF addition. Tensile, flexural, impact, and shear properties increased by 48.2%, 63.5%, 24.4%, and 52.2%, respectively. Scanning Electron microscopy (SEM) micrographs used in morphological structural analysis prove that the high mechanical values are achieved by ASF strengthening the interlaminar adhesion. This study contributed to developing a hybrid natural composite material reinforced with natural fillers that is stronger, environmentally friendly, and sustainable.Highlights The organic structure of Almond Shell Filler (ASF) ensured the sustainability of natural composites. Cellulosic ASF significantly contributed to the structural stiffness and strength of jute fiber composites. ASF reduced voids, improved fiber‐matrix bonding, and prevented debonding and delamination. ASF optimized the mechanical performance of jute fiber composites at 3%.

Effects of Mulching and Flaming on Weed Control and Almond Growth in a Newly Established Almond Orchard

This study was conducted in a newly established (2-year-old) almond orchard to investigate the effects of five different mulching materials (woven and nonwoven fabric, black and white polyethylene, almond shell) and flame treatments applied at two different frequencies (FL20 and FL30) on weed control and almond growth compared with those of conventional herbicide (glyphosate) application and weedy control. Thus, this study included nine different treatments. The impacts of these treatments on weed density and coverage were periodically monitored. Additionally, the biomass of the weeds was measured at the end of the season to evaluate the effects of the treatments. Because the almond orchard was not yet in the economic fruit-bearing stage, the effects of the treatments were examined in terms of parameters that characterize almond growth, such as plant height, trunk diameter, shoot length, and shoot thickness. The chlorophyll content and water potential values of the trees were also determined. The results of this two-season study indicated that synthetic mulches provided the best outcomes in terms of weed control and almond growth. No weed emergence was observed throughout the season in any of the synthetic mulch treatments. Although almond shells used as organic mulch were highly effective for blocking sunlight, they failed to prevent the growth of some vigorously growing perennials such as Cynodon dactylon and Sorghum halepense that emerged from gaps. Flame treatments demonstrated rapid and effective results; however, they were less successful against the aforementioned monocot perennial weeds and required frequent repetition because of the lack of residual effects. Glyphosate, an herbicide that is commonly used in conventional orcharding, was applied five times throughout the experiment and proved effective weed management compared with that of the weedy control. However, considering the increasing herbicide resistance, environmental and health issues, and growing interest in organic almond cultivation, synthetic mulch applications have emerged as good options. Despite the initially higher establishment costs, synthetic mulches effectively controlled weeds and reduced water stress, thereby promoting almond tree growth.

Environmental assessment of alkali-activated materials based on agro-industrial waste as alkaline activators through leaching tests

Global circular economy drives the development of sustainable alkali activated materials (AAM) for use as construction material from industrial by-products and wastes. The assessment of the potentially hazardous substances release of these new material combinations into the soil and groundwater over time is essential. In this study, the aim is the environmental assessment of three AAMs based on blast furnace slag (BFS), activated with almond shell biomass ash (ABA) as potassium source and three solid sources of silica from the agricultural industry, rice husk ash (RHA), spent diatomaceous earth (SDE) and bamboo leaf ash (BLA), using European horizontal leaching tests proposed for construction materials, for monolithic form, Dynamic Surface Leaching Test (DSLT) and for granular form, Up-flow Percolation Test and the Compliance leaching test, by simulating different scenarios of their entire life cycle. The leaching results of the AAM showed the effectiveness of the inertization of all the recycled materials studied, which exceeded some inert materials limits, by means of the activation process. Despite the absence of significant differences in the leaching mechanisms of the oxyanions As, Cr, Mo, Sb, Se and V between the three AAMs developed, they presented different long-term leaching behavior depending on their form, monolithic, or granular, and therefore in their different life cycle stages. Therefore, it is concluded that although the incorporation of agro-industrial waste as alternative activators in BFS based AAM according to the Dutch Soil Quality Decree (for unrestricted use of monolithic and granular materials) is an environmentally acceptable option, the design of waste derived AAMs should be assessed by means of a combination of leaching tests that cover their expected life cycle.

Enhancing hydrochar production and proprieties from biogenic waste: Merging response surface methodology and machine learning for organic pollutant remediation

The valorization of biogenic waste by hydrothermal carbonization is widely discussed in research. However, to our knowledge, no study has combined almond shells and olive pomace to synthesize a solid carbon material. The purpose of this study is to enhance the hydrochar process from AS and OP using RSM methodology and machine learning models: ANN, SVM and XG-Boost. Subsequently, a study was carried out on the removal of organic pollutants by the synthesized material. The optimum Co-HTC operating conditions obtained at 180 C, 90 min with acid catalyst corresponding to 71.51 % and 87.13 % for mass yield and carbon retention rate respectively according to RSM-CCD. The comparison between RSM-CCD and ML in terms of prediction concludes that RSM remains more efficient in terms of planning and optimization. However, ANN is more suitable for modeling and predicting mass yields and carbon retention rates. Hydrochar’s physicochemical properties were evaluated by the use of spectroscopic methods like FTIR, SEM, XRD, and CHNO. To conclude, we studied the performance of HCop in methylene blue adsorption, varying the following parameters: pH, contact time, initial dye concentration, adsorbent dose and temperature. In addition, kinetic and isothermal models were studied to describe the dominant mechanisms in the MB adsorption process. The MB maximal adsorption using HCop obtained at pH 9, with an initial dye concentration of 100 mg. L−1, 40-min contact time, 0.1 g/L adsorbent dose, and a temperature between 25 and 30 °C. In conclusion, these results provide important information on the use of Co-HTC to convert biogenic wastes into high-performance carbon materials for the appropriate removal of organic pollutants. More studies are needed to use the material in other fields of application.

From Waste to Resource: Evaluating Biomass Residues as Ozone-Catalyst Precursors for the Removal of Recalcitrant Water Pollutants

Five different biomass wastes—orange peel, coffee grounds, cork, almond shell, and peanut shell—were transformed into biochars (BCs) or activated carbons (ACs) to serve as adsorbents and/or ozone catalysts for the removal of recalcitrant water treatment products. Oxalic acid (OXL) was used as a model pollutant due to its known refractory character towards ozone. The obtained materials were characterized by different techniques, namely thermogravimetric analysis, specific surface area measurement by nitrogen adsorption, and elemental analysis. In adsorption experiments, BCs generally outperformed ACs, except for cork-derived materials. Orange peel BC revealed the highest adsorption capacity (Qe = 40 mg g−1), while almond shell BC showed the best cost–benefit ratio at €0.0096 per mg of OXL adsorbed. In terms of catalytic ozonation, only ACs made from cork and coffee grounds presented significant catalytic activity, achieving pollutant removal rates of 72 and 64%, respectively. Among these materials, ACs made from coffee grounds reveal the best cost/benefit ratio with €0.02 per mg of OXL degraded. Despite the cost analysis showing that these materials are not the cheapest options, other aspects rather than the price alone must be considered in the decision-making process for implementation. This study highlights the promising role of biomass wastes as precursors for efficient and eco-friendly water treatment processes, whether as adsorbents following ozone water treatment or as catalysts in the ozonation reaction itself.

Elemental analysis of valuable byproducts by TXRF spectrometry: coal fly ash and activated carbon

In order to ensure that byproducts are environmentally friendly and fit for purpose, their chemical composition must be determined, with special attention to elements at trace level. The large variability in the type of matrices demands a versatile analytical technique, compatible with sample preparation methods allowing both fast composition screenings and accurate quantitative analysis.In this work, byproducts derived from carbon-rich matrices, including coal fly ash and activated carbon from coconut and almond shells, were investigated by means of total reflection x-ray spectrometry and different sample preparations. Suspension, acid digestion, solid-liquid extraction and ashing were performed and assessed as to their complexity and detection capabilities, ranging from 0.01 mg/kg to 16 mg/kg, depending on the element and sample preparation. The internal standard quantification with gallium, aided by a variation of the standard additions method to take into account its possible presence in the samples, allowed to determine elements of environmental and technological interest, including K, Ca, Ti, V, Mn, Cr, Ni, Cu, Zn, Ga, As, Sr, Pb. Assets, limits and possible developments are presented and discussed.

Improved Cupressus sempervirens L. galls for methylene blue removal: adsorption kinetics optimisation using the DA-LS algorithm, characterisation, and machine learning modeling

ABSTRACT In this study, an investigation was conducted on the effectiveness of three bioadsorbents – galbuli of Cupressus sempervirens L. almond shells, and Luffa – for removing methylene blue (MB) from water. Various activation techniques and operational conditions were employed to enhance the adsorption capacity. The study focused on adsorption kinetics and equilibrium capacity. The results showed that microwave-dried galbuli of Cupressus sempervirens L. exhibited the highest adsorption capacity of 38.05 mg/g with an adsorption efficiency of 17.4%. To improve this capacity, the Dragonfly Algorithm-integrated least squares (DA-LS) was proposed to optimise the fitting of 32 adsorption isotherm models, which included a proposed modified Langmuir model. After optimisation, the sixth chemical treatment of Cupressus sempervirens L. reached a Langmuir isotherm qmax value of 84.44 mg/g, suggesting the high efficiency of the bioadsorbent compared to previous studies. Characterisation using microscopy and ATR-FTIR techniques revealed that chemical modifications led to rougher, microporous cellulose fibres and significant changes in the chemical structure, potentially enhancing the surface area and adsorption efficiency. To predict the adsorption capacity, the Support Vector Machine for Regression with DA (SVMR-DA) was utilised, achieving a root mean square error (RMSE) of 1.357 and an R2 of 0.9913. This high accuracy indicates a reliable model with a robust error distribution. These results suggest that Cupressus sempervirens L. can be an effective bioadsorbent for water treatment, with significant potential for industrial application.

Year around study of tubular solar still with green almondshells biowaste as energy storage material: energy, economic, and environmental analysis.

Solar-based desalination is one of the prominent contributors to overcoming the water scarcity problems in desert areas and a major alternative to fossil fuel-based desalination methods. The present study focuses on utilizing green almond shells (green almond shells) as energy storage materials in tubular solar still (TSS) to enhance water productivity, energy efficiency, and economic and environmental analyses. Further, this study discusses the yearly water output, annual energy efficiency, and economic and environmental analyses. Two different TSS were utilized which consists of conventional TSS (CTSS) without any storage materials and modified TSS with the inclusion of green almond shells (MTSS) in the climatic conditions of Chennai, India. The yearly distilled water output from the CTSS and MTSS was evaluated as 512 and 691.2kg/m2, respectively. The yearly distilled water output from the MTSS is 26% higher when compared to the CTSS. Furthermore, the maximum monthly energy efficiency of the CTSS and MTSS was 14.4 and 19.44%, respectively. The annual energy efficiency of the CTSS and MTSS is 12.6 and 17.02%, respectively. The economic analysis of the system is also carried out, and the findings show that better economic feasibility is achieved in MTSS considering the INR 5 (Indian Rupees) cost of water. The payback period for MTSS was 12months, while for CTSS it is calculated to be 20months. Furthermore, CO2 emission and mitigation have also been evaluated, and the results indicate that the utilization of porous material has increased the emission for MTSS, while CO2 mitigation has been significantly higher as compared to the CTSS system.

Organic soil amendment effects on soil hydrology in an almond orchard evaluated using time-lapse electrical resistivity tomography

Adding organic amendments to soils in orchards has been suggested as a climate-smart agricultural practice that can increase resilience to extremes such as drought. The benefits of adding almond hulls and shells to soil include releasing potassium into the soil, improving water infiltration, reducing soil water evaporation, and enhancing water-holding capacity. In this study, soil infiltration and root water uptake (RWU) patterns of almond trees in amended and control soil treatments were investigated. An almond orchard was mulched with a mixture of almond hulls and shells used as surface-applied organic matter amendments. The combined use of time-lapse electrical resistivity tomography (ERT), stem water potential (SWP) and leaf water potential (LWP) measurements were used to evaluate RWU, soil infiltration patterns, and tree water status at different times during the study. The results of the ERT showed that the RWU patterns for the almond trees are distinct between the amended and the control treatments after the irrigation was applied. Compared to the control treatment, the amended treatment allowed the soil to store more water. Regardless of treatment, the majority of RWU patterns were observed in the top 0.5–1 m root zone depth. Almond trees began to recover from stress, as indicated by the SWP and LWP values, four hours after the start of irrigation. In addition, this was demonstrated by the ERT measurements, which revealed the RWU activity four hours after the irrigation had been applied. This research reveals that time-lapse ERT surveys combined with soil and tree water status data can infer patterns of RWU in almond trees grown with organic soil amendments and under controlled conditions. Furthermore, it was concluded that using almond hulls and shells as organic matter amendments can help almond growers improve infiltration, making almond production more resilient to climate change-related extremes such as droughts.

Obtaining Cellulose Fibers from Almond Shell by Combining Subcritical Water Extraction and Bleaching with Hydrogen Peroxide.

Almond shell (AS) represents about 33% of the almond fruit, being a cellulose-rich by-product. The use of greener methods for separating cellulose would contribute to better exploitation of this biomass. Subcritical water extraction (SWE) at 160 and 180 °C has been used as a previous treatment to purify cellulose of AS, followed by a bleaching step with hydrogen peroxide (8%) at pH 12. For comparison purposes, bleaching with sodium chlorite of the extraction residues was also studied. The highest extraction temperature promoted the removal of hemicellulose and the subsequent delignification during the bleaching step. After bleaching with hydrogen peroxide, the AS particles had a cellulose content of 71 and 78%, with crystallinity index of 50 and 62%, respectively, for those treated at 160 and 180 °C. The use of sodium chlorite as bleaching agent improved the cellulose purification and crystallinity index. Nevertheless, cellulose obtained by both bleaching treatments could be useful for different applications. Therefore, SWE represents a promising green technique to improve the bleaching sensitivity of lignocellulosic residues, such as AS, allowing for a great reduction in chemicals in the cellulose purification processes.

Production, optimization, and characterization of biodiesel from almond seed oil using a bifunctional catalyst derived from waste animal bones and almond shell

The search for environmentally friendly alternatives to conventional fossil fuels has been intensified by the global shift toward sustainable energy sources. With over 95% of the fuel market dominated by petroleum-based products, concerns regarding their limited biodegradability and high eco-toxicity have been escalated. In response, there is a growing demand for biobased solutions that can mitigate pollution and reduce greenhouse gas emissions. In this study, the synthesis of biodiesel from waste almond seed oil (WCO) was focused on, utilizing an innovative bifunctional catalyst derived from waste animal bones and almond shells. The efficacy of the catalyst synthesized from these unconventional materials was confirmed through rigorous characterization techniques, including scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier transform infrared (FTIR) spectroscopy, and Brunauer, Emmett, and Teller (BET) analysis. The physicochemical properties of WCO and the resulting biodiesel were evaluated according to ASTM D6751 and EN 14214 standards. To optimize the catalytic process, Box Behnken Design (BBD) was employed to explore the effects of key parameters: reaction temperature (40-60°C), reaction time (60-90 minutes), catalyst loading (0.5-1.5 wt%), and methanol-to-oil ratio (6:1-18:1). Remarkably, under optimal conditions, an impressive biodiesel yield of 86.2% was achieved. Specifically, the optimal parameters were a Methanol:Oil Ratio of 6.026, Catalyst Loading of 1.49917 wt%, Reaction Time of 66.8179 minutes, and Temperature of 59.9806°C. The potential of utilizing waste materials for sustainable biodiesel production is underscored by our findings. The bifunctional catalyst developed in this study represents a cost-effective and environmentally friendly alternative to conventional catalysts, contributing to cleaner fuel production methods.

Transforming olive-processed waste and almond shells into high-quality Biofuels: a comprehensive development and evaluation approach

ABSTRACT Amidst the energy crisis, biomass energy has emerged as a pivotal solution, given its abundant distribution, impressive storage capabilities, and carbon-neutral nature. The study aims to develop biofuels of good quality using various agroalimentary waste products, Examining the pelletization process of including wet olive pomace (wet olive pomace (2 phases)(OP)), de-oiled olive pomace (DOP), olive stones (OS), and almond shells (AS), this research assesses its effectiveness in enhancing both bulk and energy densities, highlighting it as the optimal method for such enhancement. The preparation of these biofuels without binder has yielded promising results in terms of bulk density, hardness, calorific value, and ash content. Tests comparing biofuels to commercial olive pomace pellets (COP) showed the following: Using biomass with moisture content below 15%, granulometry of 1 mm or smaller, and no binder produces high-quality pellets. These pellets had high density (889, 675, 643, and 621 kg/m3), high hardness (99.18%, 99.80%, 98.92%, and 99.14%), and high heating values (18.93, 20.29, 22.51, and 20.38 MJ/kg) at average temperatures and pressures. These results are comparable to those of commercial products. In general, biomass and solid biofuels offer credible alternatives to produce energy in the form of electricity, heat, or both, using various processes, such as combustion, pyrolysis, and gasification. The knowledge gained from this research is very helpful in developing and improving bioenergy systems and promoting sustainable methods of producing energy from agricultural wastes.