Optimization of pyrolysis conditions for Catha edulis waste-based biochar production using response surface methodology

Biomass from specialty crops, including almonds, walnuts, and numerous others, serves as an important resource for energy and materials as agricultural systems evolve towards greater sustainability and circularity in management and operations. Biochar was produced from almond shells in a laboratory furnace at temperatures between 300 and 750 °C for residence times of 30 and 90 min with moisture contents of 5% to 15% wet basis. Response surface methodology was used to optimize the biochar yield. Feedstock and product temperatures were continuously monitored throughout the experiments. In addition, larger batches of biochar were also produced in a fixed-bed pilot-scale pyrolyzer. The yield of biochar was determined as a weight fraction of the amount of oven-dry almond shells used in each experiment. Physical and chemical characteristics of biochars were evaluated. Pyrolysis temperature and time were found to be the significant parameters affecting the biochar yield, with second-order regression models derived to fit yield results. As anticipated, highest biochar yields (65%) were obtained at a pyrolysis temperature of 300 °C and a pyrolysis time of 30 min due to the limited volatilization at this short residence at low temperature affecting torrefaction of the feedstock. The average biochar yield from the fixed-bed pilot-scale experiments was 39.5% and more closely aligned with the fixed carbon from standard proximate analyses. Higher pyrolysis temperatures resulted in higher C:N ratio and pH with the highest C:N ratio of 19:1 and pH of 10.0 obtained at a pyrolysis temperature of 750 °C for 90 min. Particle density increased with the increase of pyrolysis temperature. Results of this study can aid in predicting biochar yields from almond shells under different pyrolysis conditions and determining the amount of biochar required for different applications.

Thermogravimetric analysis and the optimisation of bio-oil yield from fixed-bed pyrolysis of rice husk using response surface methodology (RSM)

Abstract: Densification is required for efficiently handling and transporting biomass as feedstock for biofuel production. Binders can enhance straw pellet strength and improve the pellet performance. The present investigation aimed to optimize binders and compression load for wheat straw pelletization using a single pelleting unit. Response surface methodology was employed by using a four-factor, five-level central composite design with wood residue (%, w/w), bentonite (%, w/w), crude glycerol (%, w/w), and compression load (N) as process parameters. The pellet tensile strength, specific energy consumption of pelleting, and pellet density were the response variables. The higher heating value, ash content of the pellet product and the cost of the feedstock were also considered in optimizing binder addition. The developed model fitted the data and was adequate for binder analysis and optimization. Wheat straw pellet, with the addition of 30% wood residue, 0.80% bentonite, and 3.42% crude glycerol, in addition to 4 000 N of compressive load, was identified as optimal with good performance of pellet tensile strength (1.14 MPa), specific energy consumption (32.6 kJ/kg), and pellet density (1 094 kg/m3) as well as low ash content (6.13%) and high heating value (18.64 MJ/kg). Confirmation tests indicated high accuracy of the model. Keywords: biomass, wheat straw pellet, binder, wood residue, bentonite, crude glycerol, RSM, compression load DOI: 10.3965/j.ijabe.20140706.009 Citation: Lu D H, Tabil L G, Wang D C, Wang G H, Wang Z Q. Optimization of binder addition and compression load for pelletization of wheat straw using response surface methodology. Int J Agric & Biol Eng, 2014; 7(6): 67－78.

This work aimed to extract fixed oil from moringa seeds by optimizing the oil extraction process parameters with the aid of response surface methodology (RSM). The effects of three independent oil extraction process factors particle sizes (0.3–0.7 mm), temperature (50–70 °C) and time (6–8 h) for oil extraction from moringa seeds were studied. The proximate analysis of moringa seeds: ash content, acid value, ester value and saponification value were 5 ± 0.46, 2 ± 0.77, 257 ± 73 and, 260 ± 0.50wt.%, respectively. A quadratic model was used to correlate the interaction effects of the independent variables for maximum oil extraction at the optimum process parameters by employing central composite design (CCD) with RSM. The work indicates that the interaction of temperature and particle sizes is the most significant parameters among the model terms, followed by the interaction of temperature and extraction time effect on oil yield and finally, interaction of particle sizes and extraction time had no significant effect on oil yield. The studied results reported a better oil yield: 43.18 ± 0.52% at extraction temperature of 59.79 °C, particle size of 0.41 mm and extraction time of 6.54 h with supported a maximum desirability of 1. The oil obtained was analysed for various parameters: acidity value 2.2 ± 0.05, iodine value 63.4 ± 0.08, refractive index 1.52 ± 0.01 and density 0.90 ± 0.01. This study concludes that oil obtained from moringa seeds could be utilized as a source of edible oil for human consumption.

Optimization of pyrolysis parameters for enhanced biochar production from agricultural biomass: A study on energy efficiency and carbon sequestration potential.

Parametric influence of process conditions on thermochemical techniques for biochar production: A state-of-the-art review

Based on a systematic review, 19 case studies were selected, focusing on the production of biochar through pyrolysis of five lignocellulosic biomasses (olive husk, beech wood, corncob, spruce wood, and hazelnut shell), under constant pressure (0.1 MPa) and temperature from 650.2 to 973.0 K. Interactions between process variables (temperature, residence time of the vapor phase and heating rate), biomass chemical composition variables (lignin, holocellulose, ash, carbon, nitrogen, oxygen and hydrogen content) and biochar yield-CY were evaluated by Pearson’s correlation matrix and Principal Component Analysis-PCA. Strong correlations (|r| ≥0.75, p<0.05) were found for lignin and CY (0.78); carbon and CY (0.76); nitrogen and CY (0.77). Three variables of biomass chemical composition were the most important ones for the first principal component-PC1; process variables (heating rate and the vapour residence time) were the most important ones for the second principal component-PC2. Experiments with hazelnut shell as feedstock were associated with higher CY.

Pyrolysis of peanut shell: Kinetic analysis and optimization of thermal degradation process

Due to rapid development in some countries that puts increasing urgency on the global community to replace non-renewable resources, Interest in harnessing energy from other sources like biomass has grown immensely in recent years. Biomass can be converted to energy through thermo-chemical and biological conversion routes. Pyrolysis is one the thermo-chemical methods to transform biomass into useable fuels. Pyrolysis conducted without the presence of oxygen at high temperatures results in the production of biochar, bio-oil and gases. The aim of this work was to perform pyrolysis experiments for durian rinds with the emphasis on the characterization of the rinds and their biochars. The pyrolysis of durian rinds was performed in a horizontal tubular reactor at temperatures ranging from 300 to 700 °C. The effects of temperature together with holding time on the yield of biochar and heating value were investigated. It was found that the pyrolysis operating temperature had a significant effect on the yield of biochar, heating value and elemental composition of the biochar. Increment of pyrolysis temperature from 300 to 700 °C, showed a decrease in the total biochar yield, while the heating value increased. The optimum temperature was found at 325 °C with a holding time of two hours. The biochar yield obtained at optimum temperature was 40.8 %wt with a heating value of 28.7 MJ/kg. In conclusion, the results from the pyrolysis showed the durian rinds has potential to be converted into solid biofuel that can be used for energy application.

Synergetic effect of co-pyrolysis of sewage sludge and lignin on biochar production and adsorption of methylene blue

Biochar has been known to be an excellent soil amendment. However, the biochar yield and its quality are both affected by the process parameter, such as temperature and heating time, and the production method from kiln type used. Therefore, the objective of this work was to characterize the thermal distribution inside the 50-liter kiln at different heating times of the biochar production. The experiments on the kiln with a dimension of 500 mm × 380 mm (height × diameter) including the fuel core with diameter of 115 mm with 5 rows of 6.35 mm drill puncture diameters were conducted. The biochar was produced from 7 kg of agricultural waste corncob. The pyrolysis temperature increased with increasing heating time and it was controlled not exceeding 600 °C by adjusting the briquette fuel quantity. The results showed that the highest temperature was found at the fuel core and decreased in radial direction outwards to the kiln wall. The heating time showed effect on the thermal distribution as well as the biochar yield. The lower thermal gradient and the higher biochar yield were obtained at the higher heating time. The biochar yield would, however, decrease after optimal heating time due to the decomposition and degradation of biochar derived from corncob during the pyrolysis process. The production cost of biochar was also determined. These findings propose agriculturists the optimal heating time along with the production cost to facilitate the biochar production.

Combining biomass, a clean and renewable energy source, with waste plastic, which serves as a good auxiliary fuel, can produce high-quality clean fuel. The performance of biomass-derived fuel can be improved by torrefaction. This study optimized the co-torrefaction of fungus bran and polypropylene (PP) waste plastic to obtain clean solid biofuel with high calorific value and low ash content (AC) using response surface methodology. Two sets of mixed biochars were investigated using a multiobjective optimization method: mass yield-higher heating value-ash content (MY-HHV-AC) and energy yield-ash content (EY-AC). PP increased the heat value, decreased AC, and acted as a binder. The optimal operating conditions regarding reaction temperature, reaction time, and PP blending ratio were 230.68 °C, 30 min, and 20%, respectively, for the MY-HHV-AC set and 220 °C, 30 min, 20%, respectively, for the EY-AC set. The MY-HHV-AC set had properties close to those of peat and lignite. Furthermore, compared with that of the pure biochar, the AC of the two sets decreased by 15.71% and 14.88%, respectively, indicating that the prepared mixed biochars served as ideal biofuels. Finally, a circular economy framework for biobriquette fuel was proposed and prospects for preparing pellets provided.

Biochar yield prediction plays a critical role in optimizing pyrolysis processes and advancing sustainable biomass utilization. This study introduces a hybrid machine learning framework that integrates Decision Tree models with four optimization strategies including Tabu Search, Ant Colony Optimization, Evolutionary Strategies, and Batch Bayesian Optimization (DT-BBO). A curated dataset of 211 samples was preprocessed using Leverage outlier detection and normalization to ensure model robustness. Among all tested models, the DT-BBO approach achieved the highest accuracy, with an R2 of 0.98, an MSE of 1.9, and an AARE% of 2.2%, outperforming the other optimization techniques. SHAP analysis revealed that pyrolysis temperature, residence time, and ash content were the most influential parameters governing biochar yield. Comparative benchmarking against previously published models confirmed the superior predictive capability and stability of the proposed framework. The results demonstrate that the DT-BBO model offers a scalable, interpretable, and high-performing solution for biochar yield prediction, contributing to methodological innovation and sustainable biomass valorization.

Biochar characteristics and application rates affecting corn growth and properties of soils contrasting in texture and mineralogy

The use of exhausted grape marc to produce biofuels and biofertilizers: Effect of pyrolysis temperatures on biochars properties