Thermal decomposition of castor oil, corn starch, soy protein, lignin, xylan, and cellulose during fast pyrolysis

Ionic liquid catalyzed low-temperature hydrothermal carbonization of sewage sludge to produce hydrochar with low heavy metal content and positive energy recovery

An ionic liquid (IL, [DMAPA]HSO4) was prepared to facilitate the removal of heavy metals by hydrothermal carbonization (HTC) in sewage sludge (SS) and to obtain a positive energy recovery (ER, (Energyoutput/Energyinput - 1) > 0). The results found that the removal efficiencies of the Fe, Mn, Zn, Co, and Cd from SS exceeded 75 % with positive ER (6 %) at 20 wt% IL dosage (IL:SS). IL promoted the HTC reactions of proteins and polysaccharides to produce fixed carbon and small molecule polymers. The process mainly relies on IL to catalyze the dehydration and graphitization of SS and to destroy the heavy metal binding sites such as carboxyl and hydroxyl groups. Additionally, IL aids in constructing the macropore structures in hydrochar, thereby facilitating the release of heavy metals and water during the HTC process. This discovery holds promise for removing heavy metals from SS by one-pot HTC processes with positive energy recovery.

Pyrolytic mechanisms of typical organic components of sewage sludge in the presence of CaO: Polysaccharides, proteins, and lipids

The addition of CaO could facilitate the conversion of sewage sludge (SS) from waste to high-purity syngas. The pyrolytic characteristics of SS are a comprehensive manifestation of polysaccharides, proteins, and lipids, while the influence of CaO on their pyrolytic characteristics is rarely reported. This study conducted a thorough investigation into the pyrolytic mechanism of starch, protein, and lipid in the presence of CaO by analysing their thermal behavior, gaseous products, liquid tar, and residual char. The findings from TGA, GC, GC-MS, and FT-IR analysis indicate that the addition of CaO catalytically lowers the pyrolysis temperature of starch, protein, and lipid components and promotes their conversion into small molecules, resulting in increased syngas production. Moreover, the combination of char with the carbonation and calcination cycle of CaO leads to a significant boost in syngas (H2 and CO) yield, with up to 3 and 10 times increase from starch and protein, respectively, and a higher syngas selectivity of up to 65 %. The study also identifies those polysaccharides and proteins are the primary sources of syngas. This study can provide further insight into SS pyrolysis for syngas production in the presence of CaO and the necessary parameters to predict the pyrolysis behavior of SS in industrial applications.

A novel magnetic sludge biochar was prepared by making full use of internal iron in sludge combining KMnO4-NaOH modification to enhance the adsorption of Pb (Ⅱ), Cu (Ⅱ) and Cd (Ⅱ)

This study synthesized novel magnetic biochar (PCMN600) by KMnO4-NaOH combined modification using iron-containing pharmaceutical sludge to remove toxic metals from wastewater effectively. Various characterization experiments of engineered biochar showed that the modification process introduced ultrafine MnOx particles on the carbon surface and resulted in higher BET surface area and porosity along with more oxygen-containing surface functional groups. Batch adsorption studies indicated that the maximum adsorption capacities of PCMN600 for Pb2+, Cu2+ and Cd2+ were 181.82 mg/g, 30.03 mg/g and 27.47 mg/g, respectively, at a temperature of 25 °C and pH of 5.0, which were much higher than that of pristine biochar (26.46 mg/g, 6.56 mg/g and 6.40 mg/g). The adsorption datums of three toxic metal ions fitted well to the pseudo-second-order model and Langmuir isotherm, and the sorption mechanisms were identified as electrostatic attraction, ion exchange, surface complexation, cation-π interaction and precipitation. The strong magnetic properties of the engineered biochar endowed the adsorbent with remarkable reusability, and after five cycles of recycling, PCMN600 still retained nearly 80% of its initial adsorption capacities.

Kill two birds with one stone: The management of hazardous waste and the preparation of efficient adsorbents for Pb(II) were realized by the pyrolysis of penicillin mycelial dreg

The penicillin industry produces a large amount of penicillin mycelial dreg (PMD), potentially causing severe environmental problems without proper treatment and disposal. To achieve the goals of PMD management, the present work explored the potential of PMD as a novel feedstock to produce biochar with very high adsorption performance. PMD was pyrolyzed at 400-800 °C to prepare biochars (PMD-BCs), and the physical and chemical properties were characterized using various methods. The adsorption capacities of Pb²⁺ on PMD-BC400, PMD-BC600, and PMD-BC800 were 37.04, 62.89, and 107.53 mg/g, respectively, at a temperature of 25 °C and pH of 5.0. The adsorption process of Pb²⁺ on PMD-BCs can be well described by the Langmuir model and pseudo-second-order model. Mineral precipitation, ion exchange, functional group complexation and Pb²⁺-π interaction were involved in the adsorption of Pb²⁺ on PMD-BCs. Moreover, mineral precipitation and ion exchange dominated Pb²⁺ sorption on PMD-BCs (84.71-92.73%). This study indicates the transition of PMD to biochar for Pb²⁺ adsorption is a promising method for PMD utilization.

Trace Metals, Crude Protein, and TGA-FTIR Analysis of Evolved Gas Products in the Thermal Decomposition of Roasted Mopane Worms, Sweet Corn, and Peanuts

The thermal behavior of mopane worms (Imbrasia belina), roasted peanuts (Arachis hypogaea L.), and sweet corn (Zea mays L. saccharata) was investigated under inert conditions using the TGA-FTIR analytical technique heated from 64 to 844°C at a heating rate of 20°C/min. The degradation patterns of the food samples differed as sweet corn and peanuts exhibited four degradation stages 188, 248, 315, and 432°C and 145, 249, 322, and 435°C, respectively. Mopane worms displayed three (106, 398, and 403°C). The different decomposition patterns together with the types of evolved gases shown by FTIR analysis justified the varied biochemical and chemical composition of foods. The common evolved gas species between the food samples were H₂O, CO₂, P=O, CO, and CH₄ but mopane worms showed two extra different bands of C-N and N-H. Higher volumes of evolved gases were recorded at temperatures between 276 and 450°C, which are higher than the usual cooking temperature of 150°C. This means that the food maintained its nutritional value at the cooking temperature. Mopane worms were found to contain twice and four times crude protein content than peanuts and corn, respectively. Only total arsenic metal was reported to be above threshold limits.

A review on lignin pyrolysis: pyrolytic behavior, mechanism, and relevant upgrading for improving process efficiency

Lignin is a promising alternative to traditional fossil resources for producing biofuels due to its aromaticity and renewability. Pyrolysis is an efficient technology to convert lignin to valuable chemicals, which is beneficial for improving lignin valorization. In this review, pyrolytic behaviors of various lignin were included, as well as the pyrolytic mechanism consisting of initial, primary, and charring stages were also introduced. Several parallel reactions, such as demethoxylation, demethylation, decarboxylation, and decarbonylation of lignin side chains to form light gases, major lignin structure decomposition to generate phenolic compounds, and polymerization of active lignin intermediates to yield char, can be observed through the whole pyrolysis process. Several parameters, such as pyrolytic temperature, time, lignin type, and functional groups (hydroxyl, methoxy), were also investigated to figure out their effects on lignin pyrolysis. On the other hand, zeolite-driven lignin catalytic pyrolysis and lignin co-pyrolysis with other hydrogen-rich co-feedings were also introduced for improving process efficiency to produce more aromatic hydrocarbons (AHs). During the pyrolysis process, phenolic compounds and/or AHs can be produced, showing promising applications in biochemical intermediates and biofuel additives. Finally, some challenges and future perspectives for lignin pyrolysis have been discussed.

Biomass Behavior upon Fast Pyrolysis in Inert and in CO2-Rich Atmospheres: Role of Lignin, Hemicellulose and Cellulose Content

The present work focuses on the quality of char and primary tar produced from fast pyrolysis in N2 and CO2 of lignocellulosic biomasses: walnut shells (lignin-rich), straw (hemicellulose-rich) and pinewood (cellulose-rich). Heat treatments are carried out in a heated strip reactor (HSR) at 1573 and 2073 K for 3 s, with a heating rate of 104 K/s. The equipment allows for quenching the volatiles as soon as they are emitted. Chars are analyzed by thermogravimetric analysis in air. Results are compared with the products obtained from raw lignin, pure cellulose and pure hemicellulose. Cellulose and hemicellulose tars are dominated by anhydrous monosaccharides, which are scarce in straw tar and abundant in walnut shells tar. Polycyclic aromatic hydrocarbons PAHs are present in the primary products, in particular for walnut shells. The most reactive char is the one obtained from straw and the least reactive is the walnut shells char. Severe heat treatment and a CO2 atmosphere generate additional char components with higher and lower reactivity. The more reactive char component may arise from cross-linking reactions involving the monosaccharides (for which the result decreased in tar), whereas the less reactive component arises from thermal annealing and graphitization. Thus, the pyrolytic behavior of biomasses cannot be reconstructed with a mere addition of the lignin/cellulose/hemicellulose contribution, taking into account their content in the biomass.

Experimental study on pretreatment effects of [BMIM]HSO4/ethanol on the thermal behavior of cellulose

Ionic liquids (ILs) have been investigated to dissolve and/or pre-treat cellulose by combining with a low viscous co-solvent. Dissolution and pretreatment of cellulose by ILs are dynamic processes of dissolution and precipitation, which would caused the physical and chemical changes (such as crystallinity and thermal stability) of un-dissolved cellulose residues. Hence, this study focused on the thermal behavior of un-dissolved cellulose (PCEL) after pre-treatment using [BMIM]HSO4/ethanol. Ethanol was used as a green and cheap co-solvent of 1-butyl-3-methylimidazolium hydrogen sulfate ([BMIM]HSO4) to pre-treat cellulose under different conditions. The pretreatment effect on thermal behavior of PCEL was investigated by thermogravimetric analysis and the distributed activation energy model. [BMIM]HSO4/ethanol pretreatment efficiently lowered the thermal stability of cellulose, and promoted the thermal decomposition at low temperature. The thermal behavior of PCEL can be adjusted by the [BMIM]HSO4 mass concentration.

A Study of the Pyrolysis Products of Kraft Lignin

In order to valorize lignin wastes to produce useful aromatic compounds, the thermal degradation pyrolysis of Kraft lignin in the absence of catalysts has been investigated at 350, 450, and 550 °C. The high content of sulfur in the fresh sample led to the formation of S-containing compounds in products whose evolution in the gas phase was monitored through GC-MS analysis. Pyrolytic gas is rich in CH4, CO, CO2, and H2S with the presence of other sulfur compounds in smaller amounts (i.e., CH3SH, CH3-S-CH3, SO2, COS, and CS2). Biochar morphology and elemental composition have been investigated by means of SEM and EDX. The carbon content reaches ~90% after pyrolysis at 550 °C, while the oxygen content showed a decreasing trend with increasing temperature. From GC-MS analysis, bio-oil resulted rich in alkyl-alkoxy phenols, together with (alkyl)dihydroxy benzenes and minor amounts of hydrocarbons and sulfur compounds. NaOH/H2O and EtOH/H2O extraction were performed with the aim of extracting phenolic-like compounds. Sodium hydroxide solution allowed a better but still incomplete extraction of phenolic compounds, leaving a bio-oil richer in sulfur.

Investigation on thermal degradation kinetics and mechanisms of chicken manure, lignite, and their blends by TGA

In this study, thermogravimetric analysis (TGA) was performed under the air environment for four different heating rates (10, 20, 30, and 40 °C min^-1) in order to find out thermal degradation and mechanisms of the chicken manure, a Turkish lignite, and their blends (25 lignite + 75 manure, 50 lignite + 50 manure, and 75 lignite + 25 manure). To calculate thermal kinetics and responsible solid-state mechanisms of the samples, the Flynn-Wall-Ozawa and Coats-Redfern methods were applied. Significant differences between Turkish lignite and chicken manure samples were observed in terms of thermal kinetics and mechanisms. D1 and D4 mechanisms were found to be the responsible mechanisms for the main oxidation region of the lignite and chicken manure/blends, respectively. A similar decreasing trend for the calculated activation energies and pre-exponential constants was observed with increasing biomass content in the manure blends from 25 to 75% by both Flynn-Wall-Ozawa and Coats-Redfern methods. Furthermore, biomass content has an effect on the mechanisms of chicken manure blends during the combustion. D3 was found to be the responsible solid-state mechanism for the third regions (pre-combustion of the manure) of the chicken manure samples. However, D1 and D2 mechanisms were found to be responsible mechanisms for the blends.

Machine learning prediction and optimization of bio-oil production from hydrothermal liquefaction of algae

Hydrothermal liquefaction (HTL) of algae is a promising biofuel production technology. However, it is always difficult and time-consuming to identify the best optimal conditions of HTL for different algae by the conventional experimental study. Therefore, machine learning (ML) algorithms were applied to predict and optimize bio-oil production with algae compositions and HTL conditions as inputs, and bio-oil yield (Yield_oil), and the contents of oxygen (O_oil) and nitrogen (N_oil) in bio-oil as outputs. Results indicated that gradient boosting regression (GBR, average test R² ∼ 0.90) exhibited better performance than random forest (RF) for both single and multi-target tasks prediction. Furthermore, the model-based interpretation suggested that the relative importance of operating conditions (temperature and residence time) was higher than algae characteristics for the three targets. Moreover, ML-based reverse and forward optimizations were implemented with experimental verifications. The verifications were acceptable, showing great potential of ML-aided HTL for producing desirable bio-oil.

Selective biosorption mechanism of methylene blue by a novel and reusable sugar beet pulp cellulose/sodium alginate/iron hydroxide composite hydrogel

A cellulose-based sodium alginate/iron hydroxide (C/SA/Fe) composite hydrogel was fabricated by using epichlorohydrin as cross-linking agent as an effective adsorbent for dye. The physicochemical structure of the C/SA/Fe hydrogel was characterized by SEM, FTIR, XRD and TG. The adsorption performance for the removal of methylene blue (MB) was investigated. In addition, the selective adsorption of cationic dye was also studied. The FTIR analysis revealed that the Fe(OH)₃ colloidal particles was successfully combined in the cellulose/sodium alginate hydrogel. The modified hydrogel had better adsorption performance, and the maximum adsorption capacity of C/SA/Fe0.5 for MB was 105.93 mg/g according to the fitting results of adsorption isotherm. The kinetic study showed that MB adsorption of C/SA/Fe was more consistent with the pseudo-second-order model, and the adsorption of MB in C/SA/Fe was dominated by chemisorption mechanism such as ion exchange or electron sharing. The adsorption data fits well with the Langmuir model. Thermodynamics analysis showed that the MB adsorption by C/SA/Fe was exothermic, spontaneous, favorable and feasible. After five adsorption-desorption cycles, the adsorption capacity was almost unchanged. So, the C/SA/Fe hydrogel is a potential material in the field of the recovery of agricultural by-products or other bio-based cellulose, or environmental protection, etc.

Stochastic modelling of cellulose hydrolysis with Gauss and Weibull distributed transition probabilities

Two Markov-type stochastic models were developed to describe the kinetics of acid hydrolysis of cellulose. One of them involved a Gauss (normal) distribution of probabilities of chemical bond breaking, the other a Weibull distribution. It was considered that the random breaking of cellulose was based on the cleavage of a parent macromolecule into two descendants. Model equations and kinetics of acid hydrolysis of cellulose consisting of 10 and 100 units of cellobiose were presented. The effects of acid concentration and temperature on the kinetics of hydrolysis process were taken into account. The results obtained applying both stochastic models were in a reasonable agreement with those obtained using a deterministic kinetic model. These stochastic models can accurately describe the kinetics of acid hydrolysis and cover the drawbacks of some deterministic kinetic models, e.g., large number of model equations and parameters, modification of parameter values by changing the process conditions.

Thermodynamics, kinetics and thermal decomposition characteristics of sewage sludge during slow pyrolysis

Pyrolysis has shown great potential for sewage sludge valorisation and management by producing value-added chemicals. Although the product process yields are extensively studied, a few studies exist without consensus on the kinetic properties of sewage sludge pyrolysis. As a result, a study to investigate the thermal decomposition characteristics of Gauteng sewage sludge (GSS) at various heating rates (10, 20, and 30 °C/min), its pyrolysis kinetic parameters, reaction mechanism and thermodynamic properties was meticulously conducted. The results show that sewage sludge decomposition occurs in three stages, whereby the main decomposition (active pyrolysis) takes place at 150-570 °C. Fourier transform infrared spectroscopy (FTIR) analysis results confirm progression of thermal decomposition of GSS and drive off volatile compounds and formation of aromatic structures during TGA studies of GSS. An increase in heating rate shifts the characteristic temperatures towards higher temperatures with the highest decomposition rate of 1.10%/min.mg at 30 °C/min. The activation energies of GSS pyrolysis were calculated using Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose and Starink methods and averaged as 225.92, 218.04 and 218.97 kJ/mol, respectively. GSS pyrolysis involves complex reaction chemistry with high reactivity whereby reactions that follow third order and three-dimensional diffusion-reaction mechanisms dominated the process. However, these mechanisms cannot be used explicitly to define the global pyrolysis kinetics due to the occurrence of multiple simultaneous reactions. The obtained thermodynamic and kinetic data will advance and amplify the design, simulation and optimisation of global energy pyrolysis units for production of value-added chemicals.

Effect of potassium on the pyrolysis of biomass components: Pyrolysis behaviors, product distribution and kinetic characteristics

Potassium is an inorganic mineral element in biomass and has a significant catalytic effect on biomass pyrolysis. In this work, the effect of potassium on the pyrolysis of biomass components (cellulose, xylan and lignin) was investigated with the help of thermogravimetric analyzer coupled to fourier transform infrared spectrometer (TG-FTIR) and pyrolysis-gas chromatography coupled to mass spectrometry (Py-GC/MS). The results showed that potassium accelerated the start of the main pyrolysis stage of the biomass components, reduced the weight loss rate for cellulose and lignin, and increased the weight loss rate for xylan. On the other hand, potassium presented a promotion effect on the formation of char for cellulose but a suppression effect for lignin. In addition, an increasing potassium content promoted the release of volatile products for xylan. Product distribution analysis found that potassium promoted the scission of glycosidic bonds and the decomposition of glucose units, resulting in a sharp yield decrease of carbohydrates and a yield increase of furans, aldehydes and ketones. In addition, an increased production of CO₂ was obtained, indicating that potassium favors the cleavage and reforming of carboxyl (COOH) and carbonyl (CO) groups. Furthermore, the effect of potassium on the pyrolysis of cellulose and xylan was stronger than that on lignin pyrolysis. The effect on the pyrolysis reaction also resulted in a higher activation energy for the decomposition of biomass components, especially at high temperature intervals. Moreover, the higher the content of potassium added, the greater the increase was in the activation energy.

Isothermal Kinetic Analysis of the Thermal Decomposition of Wood Chips from an Apple Tree

The thermal decomposition of wood chips from an apple tree is studied in a static air atmosphere under isothermal conditions. Based on the thermogravimetric analysis, the values of the apparent activation energy and pre-exponential factor are 34 ± 3 kJ mol−1 and 391 ± 2 min−1, respectively. These results have also shown that this process can be described by the rate of the first-order chemical reaction. This reaction model is valid only for a temperature range of 250–290 °C, mainly due to the lignin decomposition. The obtained results are used for kinetic prediction, which is compared with the measurement. The results show that the reaction is slower at higher values of degree of conversion, which is caused by the influence of the experimental condition. Nevertheless, the obtained kinetic parameters could be used for the optimization of the combustion process of wood chips in small-scale biomass boilers.

Synergistic effect, kinetic and thermodynamics parameters analyses of co-gasification of municipal solid waste and bituminous coal with CO2

Co-gasification of municipal solid waste (MSW) with bituminous coal (BC) is an attractive alternative to realize the harmless disposal and energy harvesting of MSW. In this work, co-gasification characteristics and synergistic interaction of MSW and BC with CO₂ atmosphere are studied by thermogravimetric method, including analyses of thermodynamics, kinetic parameters and reaction mechanism function. Results indicate that MSW gasification process can be divided into four main stages, and that of BC has only three main stages. Gasification temperature of coal char is much higher than that of MSW char, and addition of MSW can significantly improve the gasification reactivity of BC. Besides, a significant synergistic effect is observed for all the blends in char gasification stage. Based on three kinetic methods of Flynn-Wall-Ozawa (Xie et al., 2018), Starink (Zhang et al., 2019a) and Friedman, the minimum average activation energy E_a (184.13 kJ/mol) is obtained when the blend ratio of BC is 40% which might be an optimal option for co-gasification of the blends. The average values of the enthalpy, the Gibbs function and the entropy changes for sample 60MSW40BC are 176.82 kJ/mol, 257.89 kJ/mol and -89.16 J/mol·K, respectively. According to the Malek method, F6, A1 and D7 models are probably more suitable to describe three main stages of sample 60MSW40BC CO₂ co-gasification.

Novel insight into pyrolysis behaviors of lignin using in-situ pyrolysis-double ionization time-of-flight mass spectrometry combined with electron paramagnetic resonance spectroscopy

In-situ detection on primary volatiles and stable radicals is of great importance for better understanding of lignin pyrolysis mechanisms and utilization. In this study, a novel in-situ pyrolysis time-of-flight mass spectrometry with double ionization sources was taken to in-situ detect primary volatiles and gas products, and the evolution of stable radicals in lignin pyrolysis residues was explored by EPR spectroscopy. The results show that the cleavage of β-O-4 linkage is mainly responsible for lignin depolymerization at 100-300 °C, releasing the G-type compounds. And these G-type compounds can further undergo O-CH₃, C_ar-OCH₃ and C_ar-OH bonds cleavage to form biphenolic hydroxyl compounds, phenols and aromatic hydrocarbons. According to the EPR analysis, the radical concentration increased from 10¹⁷ to 10¹⁹ spins/g with the temperature, and stable free-radical species are mainly composed of the o-methoxy and hydroxyl substituted phenoxy radicals and carbon-centered aromatic radicals, which can well interpret the demethylation, demethoxylation and dehydroxylation mechanisms.

Determination of Hemicellulose, Cellulose, and Lignin Content in Different Types of Biomasses by Thermogravimetric Analysis and Pseudocomponent Kinetic Model (TGA-PKM Method)

The standard method for determining the biomass composition, in terms of main lignocellulosic fraction (hemicellulose, cellulose and lignin) contents, is by chemical method; however, it is a slow and expensive methodology, which requires complex techniques and the use of multiple chemical reagents. The main objective of this article is to provide a new efficient, low-cost and fast method for the determination of the main lignocellulosic fraction contents of different types of biomasses from agricultural by-products to softwoods and hardwoods. The method is based on applying deconvolution techniques on the derivative thermogravimetric (DTG) pyrolysis curves obtained by thermogravimetric analysis (TGA) through a kinetic approach based on a pseudocomponent kinetic model (PKM). As a result, the new method (TGA-PKM) provides additional information regarding the ease of carrying out their degradation in comparison with other biomasses. The results obtained show a good agreement between experimental data from analytical procedures and the TGA-PKM method (±7%). This indicates that the TGA-PKM method can be used to have a good estimation of the content of the main lignocellulosic fractions without the need to carry out complex extraction and purification chemical treatments. In addition, the good quality of the fit obtained between the model and experimental DTG curves (R2Adj = 0.99) allows to obtain the characteristic kinetic parameters of each fraction.

Effects of hemicellulose, cellulose and lignin on the ignition behaviors of biomass in a drop tube furnace

The aim of this work was to investigate the effects of cellulose, hemicellulose and lignin on the ignition behaviors of biomass. The ignition events of three components and five types of single biomass particles were captured by a high-speed camera in a drop tube furnace with a temperature of 1273 K, and the combustion temperatures for the single biomass particles were measured by radiant energy analysis technology. The comparison of the flame images and the temperature evolution of five types of biomass with three components shows that the lignin content in the biomass particle strongly influences the ignition behaviors. The ignition mechanism of the biomass particle depends heavily on the lignin content. After homogeneous ignition, the rate of increase in the flame temperature and the char ignition of biomass are closely related to the lignin content. The ignition temperature of the biomass particle depends mainly on the cellulose component.

Comparative pyrolysis behaviors of stalk, wood and shell biomass: Correlation of cellulose crystallinity and reaction kinetics

In this study, the pyrolysis process of 20 kinds of biomass samples in 3 types (stalk-type, wood-type and shell-type) was investigated with thermogravimetric analyzer, and the correlation of biomass pyrolysis property with biomass chemical structure was put forward. The results showed that the pyrolysis of the 20 kinds of biomass can be classified by types as the pyrolysis of stalk-type biomass had an overlapping decomposition peak of hemicellulose and cellulose at 317 °C. However, the pyrolysis of wood-type and shell-type biomass showed two separated peaks at low temperature and the cellulose peak was higher in wood-type biomass (365 °C) compared to shell-type biomass (348 °C). The different pyrolysis process mentioned above could be due to the positive correlation between cellulose crystallinity and the decomposition temperature of cellulose as well as the activation energy at the decomposition stage of cellulose.

Mexican biomasses valorization through pyrolysis process: Environmental and costs analysis

Biomasses valorization by pyrolysis is a good option for reducing environmental problems. In this study, the environmental performance of three Mexican biomass valorizations (castor husk, coffee pulp and Pinus sawdust) by the pyrolysis was compared. The environmental impacts of all equipment involved in pyrolysis were evaluated. In addition, the financial viability of pyrolysis technology of coffee pulp was studied. The biomass with the lowest impact for all the selected categories was the Pinus sawdust, followed by castor husk and coffee pulp. The GWP category had values greater than 700 kg CO₂eq for all the biomass studied. GWP category is caused by the emissions, mainly due to the high amounts of CH₄ and CO₂ released for all the studied biomasses. Furthermore, the equipment with the greatest impact are the separator, the pyrolyzer and the cyclone. Finally, it was observed that even the least favorable biomass with the environment is viable from a financial point of view.