The thermal degradation kinetics of avocado seed biomass (Persea americana) was investigated at the heating rates of 5, 15, 20 and 25 ºC min-1 using thermogravimetric (TGA) and differential thermogravimetric (DTG) analysis techniques in the temperature range from ambient to 780 ºC. Chemical analysis of the avocado seed resulted in: 51.4% cellulose, 42.4% hemicellulose, 20.1% lignin, 2.1% ash, 5.6% extractives. The pyrolysis products were characterized via FTIR, SEM/EDS. The isoconversional methods of Ozawa-Flynn-Wall (OFW) and Kissinger-Akahira-Sunose (KAS) have yielded activation energy, Eα, varying from 36-323 kJ mol-1, respectively. The calorific value of biochars produced in the present study in the range of 265 to 475 ºC was 16,17 to 20,24 MJ kg-1, respectively, which are comparable to those reported values in the literature. Analyzing the DTG simultaneously with the addition of thermal energy, it can be seen that low molecular weight compounds represent the first degradation curves, followed by hemicellulose, cellulose and, lignin. The results obtained in the present work indicate that its feasible to prepare biochars with tunable properties from residual avocado seeds using a slow pyrolysis process, adding commercial value and reducing the environmental impact caused by the inadequate disposal of lignocellulosic materials.

In this review, we present the versatility of biomass and its derivatives obtained through thermal conversion processes (biochar and hydrochar) for applications in the development of electrochemical devices. This work highlights the generation of carbonaceous materials through pyrolysis and hydrothermal carbonization, in addition to proposing strategies to modify their physicochemical properties through activation methodologies to enhance their application as electrode materials. The processes of monitoring and degrading chemical species are discussed based on the diversity of electrodes that can be obtained with these bioderived coals, according to recent contributions available in the literature (2020-2023), which show the wide applicability of these materials in the field of electrochemistry.

Resumen La demanda de diésel en vehículos pesados se incrementa cada año en el mundo. El posible uso de combustibles alternativos como el biodiésel tiene algunas desventajas como el menor valor calorífico y su mayor viscosidad, por esta razón se requiere mejorar sus propiedades, optimizando el comportamiento de la combustión en el motor y en la reducción de las emisiones. El objetivo del trabajo de investigación es explorar las diferentes mezclas que puedan ayudar a mejorar el uso del biodiésel a través de las estrategias y avances que se han generado con el propósito de beneficiar el desempeño del motor diésel. Entre las distintas estrategias de mejoramiento del biodiésel están las mezclas de distintos bioaceites (aceites vegetales, de pirólisis y usado de cocina), mezclas del biodiésel con alcohol, con hidrógeno, el biodiésel como combustible piloto, las emulsiones del biodiésel con agua y la aplicación del biodiésel con antioxidantes, nanotubos y nanopartículas. Se concluye que para poder usar actualmente el biodiésel se lo haría con la combustión dual, en donde este representaría el combustible piloto (10 % o 20 % del combustible total del motor). Con esta estrategia se puede impulsar a otros combustibles (líquidos y gaseosos) en la combustión dual, para que con el paso del tiempo se encuentre la mezcla óptima que sea la mejor opción para el motor diésel.

Abstract The demand for diesel in heavy vehicles is increasing every year in the world, the possible use of alternative fuels such as biodiesel has some disadvantages such as the lower calorific value and its greater viscosity, for this reason biodiesel needs to improve its properties, optimising combustion behavior in the engine and helping to reduce emissions. The objective of the research work is to explore the different mixtures that can help improve the use of biodiesel through the strategies and advances that have been generated with the purpose of benefiting the performance of the diesel engine. Different biodiesel improvement strategies include blends of different biooils (vegetable oils, pyrolysis oils and used cooking oil), blends of biodiesel with alcohol, biodiesel as pilot fuel, biodiesel emulsions with water, biodiesel blends with hydrogen and the application of biodiesel with antioxidants, nanotubes and nanoparticles. It is concluded that to be able to use biodiesel currently is applying dual combustion, where biodiesel would represent as pilot fuel (10% or 20% of total engine fuel), with this strategy can be propelled to other fuels (liquid and gaseous) in dual combustion, so that over time the optimal blend of biodiesel is found and is the best choice for the diesel engine.

Bio-oils from biomass pyrolysis have a highly promising potential as biofuels or sources of chemicals. The quantitative analysis of bio-oils is quite difficult and requires many standards. In this study, we developed a methodology using only 16 standards for determining the concentration of 49 compounds, representatives of the main chemical classes commons in bio-oils, using relative response factors (RRF) and analytical curves. Five Pinus sawdust bio-oils were analyzed using a GC-MS-DB-5 capillary column (60 m). SCAN mode (from 45 to 450 Daltons) and retention indices (LPTRI) were used for qualitative analysis. For quantitative analysis, SIM mode was preferred, and analytical curves were constructed from an initial solution at 400 mg g 1 of each of the 16 standards, with concentrations ranging from 1 to 150 mg g 1 added to the internal standard (methyl hexanoate) at 70 mg g 1. After the positive identification and quantification of 9 compounds (among the 16 standards used), the other compounds were quantified using the RRF obtained from a standard solution at 30 mg g 1, considering the similarities with those identified standards. 196 compounds were identified, while 49 compounds were quantified, highlighting the monoaromatic hydrocarbons, naphthalenes, benzofurans, alkyl phenols, and catechols.

Vegetable cooking oil is used in domestic and commercial kitchens owing to its ability to modify and enhance the taste of the food through the frying process. However, as the oil is used through several frying cycles, it changes colour to dark brown and acquires an unpleasant smell. At this point, the waste oil is usually discarded, thereby finding its way into freshwater streams due to poor disposal and thus becoming an environmental pollutant. To provide an alternative, 'green' route to waste oil disposal, herein we report on the metal-free synthesis of onion-like nanocarbons (OLNCs) made from waste cooking oil via flame pyrolysis. The OLNCs were then applied in the removal of hexavalent chromium ions from aqueous solutions. The as-synthesised OLNCs were found to have similar properties (size, quasi-spherical shape etc.) to those synthesised from pure cooking oils. The Fourier-transform infrared spectroscopy data showed that the OLNCs contained C-O-type moieties which were attributed to the oxygenation process that took place during the cooking process. The OLNCs from waste oil were applied as an adsorbent for Cr(VI) and showed optimal removal conditions at pH = 2, t = 360 min, Co = 10 mg/L and Q0max = 47.62 mg/g, superior to data obtained from OLNCs prepared from pristine cooking oil. The results showed that the OLNCs derived from the waste cooking oil were effective in the removal of hexavalent chromium. Overall, this study shows how to repurpose an environmental pollutant (waste cooking oil) as an effective adsorbent for pollutant (Cr(VI)) removal. SIGNIFICANCE: • Waste cooking oil outperformed olive oil as a starting material for the production of OLNCs for the removal of toxic Cr(VI) from water. • The superior performance of the OLNCs from waste cooking oil was attributed to the higher oxygen content found on their surface and acquired through the cooking process. • Not only are the OLNCs produced from waste cooking oil effective in the removal of Cr(VI), but they can be used multiple times before replacement, which makes them sustainable.

The use of extraction technique with disposable tips (DPX) was applied for the first time for the extraction and preconcentration of Yb in samples of liquid waste from the petrochemical industry and environmental water using bioabsorbent cork. The use of cork as an extracting phase in the determination of Yb by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS) was evaluated. The pyrolysis and atomization temperatures were optimized at 1400 and 2400 °C, respectively. H2SO4, HNO3 and HCl acids were compared in the steps of cleaning the extraction phase and desorption of the analyte by DPX. The best extraction in the selected conditions was obtained with pH 8.0 and 5% v/v HCl. The recoveries were close to 100% for residual water and drinking water, 33 to 77% for produced water and 64 to 93% for river water. Tests with interfering ions in different concentrations were performed. The relative limit of quantification (LOQ) and limit of detection (LOD) were estimated at 0.03 and 0.01 µg L-1, respectively. The total time for the preparation of the samples by DPX was close to 1 min per sample. Extraction and pre-concentration were observed using DPX with a pre-enrichment factor of approximately 4 times.

In this study, we propose a microextraction method for the determination of CdII in produced waters. The process is based on the conversion of CdII ions into a hydrophobic diethyldithiocarbamate (DDTC) complex with its subsequent dispersive liquid phase microextraction (DLPME) from the aqueous medium with chloroform. The organic phase was then diluted with ethanol and Cd absorbance was measured by graphite furnace atomic absorption spectrometry (GF AAS). The experimental conditions related to the DLPME process were investigated, and the best microextraction conditions were achieved at pH = 6.0 (acetate buffer), 7.5 × 10-6 mol L-1 of DDTC, and when using 200 µL of chloroform as the extracting solvent. No dispersing solvent was needed, which allowed the recovery of approximately 140 µL of chloroform extract. Pyrolysis and atomization temperatures of the GF AAS program were determined through the construction of the respective curves. The estimated limits of detection (LOD) and quantification (LOQ) were 5 and 17 ng L-1, respectively, whereas the enrichment factor for the method was 17. Six samples of seawater and five samples of produced waters with salinities between 30 and 270‰ were analyzed as well as two certified reference materials of saline waters.

Resumen (Introducción): Latinoamérica dispone de humedales que preservan la vida silvestre, actuán como fuente purificadora del agua y previenen inundaciones, sequías y otros desastres ambientales. Actualmene, estos humedales están siendo amenazados por la eutrofización y por las malezas acuáticas, como es el caso del lirio acuático en la Presa, La Vega, Jalisco, México. (Objetivo): La presente investigación proporciona una alternativa para el manejo sustentable del lirio acuático (Eichhornia crassipes) por medio de la obtención de biocarbón y su evaluación. (Metodología): Se desarrolló un prototipo funcional de reactor de pirólisis solar. Para ello se ejecutaron 36 pruebas con el fin de pirolizar muestras de lirio acuático con 17-23 % de humedad, aplicando vacío de 5 in Hg en diferentes temperaturas (170, 200 y 230 ºC) y tiempos de residencia (120, 150, 180 y 210 min). De este modo se encontró el mejor rendimiento de biocarbón por el método de superficie de respuesta. (Resultados): La optimización del rendimiento se encontró a 170 ºC con un tiempo de residencia de 171.8 min. El biocarbón presentó un poder calorífico de 17.56 MJ/kg, 20.11 % en peso de carbón fijo y 6.89 de relación C/H (carbono-hidrógeno). (Conclusiones): Esta propuesta aporta evidencia sobre un nuevo reactor pirolítico solar que procesa el lirio acuático para la producción de biocarbón con alto poder calorífico o como un medio para fijar el carbono. Esta que podría ser una solución a uno de los efectos de la eutrofización.

Abstract (Introduction): Latin America has extensive wetland areas of international importance, since these wetlands preserve wildlife, acting as a source and purifier of water; protecting us from floods, droughts, and other environmental disasters. However, these wetlands are threatened by eutrophication and aquatic weeds, such as the water lily in La Presa, La Vega, Jalisco, Mexico. (Objective): The present investigation provides an alternative for the sustainable management of the water lily (Eichhornia crassipes) by obtaining biochar and its evaluation. (Methodology): A functional prototype of a solar pyrolysis reactor was developed, running 36 tests to pyrolyze water lily samples with 17-23% humidity, applying a 5 in Hg vacuum at different temperatures (170, 200 and 230 ºC) and residence times (120, 150, 180 and 210 min); finding the best yield of biochar by the response surface method. (Results): The optimal conditions in the reactor were found at 170 ºC, with a residence time of 171.8 min. The biochar presented a calorific value of 17.56 MJ/kg, 20.11 % by weight of fixed carbon and 6.89 C/H (carbonhydrogen) ratio. (Conclusions): This proposal provides evidence for a new solar pyrolytic reactor that processes water lily to produce high calorific biochar or to fix carbon, which could be a solution to one of the effects of eutrophication.

The liquid product of the pyrolysis of biomass is a mixture of an organic phase and other aqueous, being the last one rich in phenol monomers which can be used in industrial chemistry as input for plastic and resin production. This work aimed to develop a method for extracting phenols present in the aqueous fraction obtained from the pyrolysis of guava seeds, using ultrasonic assisted liquid-liquid extraction (UALLE) with ethyl acetate and ionic liquids (ILs) as co-solvents (1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl) amide (BMIM.NTF2) and 1-butyl-3-methylimidazolinium hexafluorophosphate (BMIM.PF6)). The percentage IL, ultrasonic bath potency, temperature, and pH were studied. Quantification of twelve phenol monomers was performed using gas chromatography-mass spectrometry (GC-MS) and the total phenol concentration (TPC) was performed using UV-Vis spectrophotometer. The ionic liquid BMIM.NTF2 was more efficient for phenol extraction than BMIM.PF6. The phenolic extractions were influenced by the pH of the aqueous fraction (higher extraction yields at pH ≤ 7), and thus, presented recoveries above 80% for both ionic liquids.

Abstract There are several investigations on the use of food waste to remove contaminants by adsorption. However, a simple route, without chemical activation reagents, is needed for the development of adsorbents. The aim of this study was to develop an adsorbent from plantain peel, using a simple procedure, and to evaluate its capacity to remove phosphate from aqueous solutions at phosphate concentrations similar to those of water sources at risk of eutrophication (0.30 mg/L). The simple pyrolysis method was used in an electric muffle, without chemical activation, using plantain peel as precursor. The variables evaluated were pyrolysis temperature and solution pH. The specific surface area BET, zero loading point of the developed treatments, was determined. Phosphate adsorption was studied in a batch experiment in the presence of calcium ions in solution. Phosphate adsorption was favorable at all three pyrolysis temperature levels (500, 600 and 700 °C) and two solution pH levels (pH 7 and 10). the pseudo-second order kinetic model was the best fit for the experimental data to describe the adsorption mechanism. The best fit to the experimental equilibrium data was obtained with the Langmuir isotherm model. It was found that a 1 g/L dose of the adsorbent was able to reduce 92% of phosphate in water, with a removal capacity 0.14 mg/g at pH 10 and pyrolysis temperature of 700 °C. This study lays the groundwork for future research on the use of this type of adsorbent in water treatment to facilitate access to clean water for rural populations.

Abstract A study of ZnO-based ceramic films prepared by the spray-pyrolysis technique is presented. Pure and Ni-doped thin film samples were deposited as a coating on a glass substrate and experimentally characterized using scanning electron and atomic force microscopies, X-ray diffraction, and UV-vis-NIR spectroscopy. The morphologic, crystallographic, and optical properties were analyzed. Structural and electronic properties were compared to predictions obtained from computational calculations based on the density functional theory plus U approach (DFT+U). All these simulations provided additional data that could be used as a reference for material modeling and a better understanding of the experimental results. It was found that spray pyrolysis can be used to produce thin film ceramic samples (~300 nm) with low amounts (<5%) of Ni impurities substitutionally located at the cationic sites of the ZnO wurtzite host structure. The results of this investigation showed that an experimental and theoretical study aided in a better characterization of the thin films, and helped to outline a more robust model of the samples.

Abstract: This research study aims to determine the operating temperature conditions and the raw material catalyst ratio in the yield of liquid fuels from the catalytic pyrolysis of polypropylene disposable face masks (GB/T32610-2016). Three-layer disposable masks are acquired and characterized. They are subjected to a pyrolysis process on a laboratory scale by using an equilibrium catalyst obtained from a Peruvian oil refinery’s catalytic cracking unit. The results show a maximum yield of 46.7% of liquid fuels at 700°C and a 0% catalyst-raw mass material ratio. It is concluded that both the operating temperature and the catalyst-raw material ratio affect liquid fuel production yield of polypropylene disposable face masks (GB/T32610-2016).

Resumen: La presente investigación tiene como objetivo determinar las condiciones de temperatura de operación y la relación catalizador-materia prima en el rendimiento de combustibles líquidos obtenidos a partir de la pirólisis catalítica de cubrebocas de polipropileno (GB/T32610-2016) desechables. Se adquirieron y caracterizaron mascarillas desechables de tres capas. Estas fueron sometidas a un proceso de pirólisis a escala de laboratorio en presencia de un catalizador de equilibrio procedente de la unidad de craqueo catalítico de una refinería de petróleo peruana. Los resultados muestran un rendimiento máximo de 46.7% de combustibles líquidos a la temperatura de 700 °C y una relación catalizador-materia prima de 0 % en masa. Se concluye que la temperatura de operación y la relación catalizador-materia prima ejercen un efecto en el rendimiento de producción de combustibles líquidos a partir de cubrebocas de polipropileno (GB/T32610-2016).

Abstract: This research study characterizes the pyrolysis kinetics potential of an oil shale in unconventional oil from the Lancones Basin (Peru). Thermogravimetry is applied in an inert medium (nitrogen) by using three heating rates (β=5, 10, 20°C/min) over a wide temperature range (25 to 800°C). The kinetic triplet is determined by the Kissinger-Akahira-Sunose isoconversional method to obtain the activation energy and the pre-exponential factor, while the kinetic model is estimated with master graphs. The results revealed average activation energy values of 81.53 and 163.08 kJ/mol and pre-exponential average value factors of 1.06x107 and 4.07x107 min-1 for the kinetic models of diffusion (D1) and cylindrical contraction (R2). The kinetic triplet is validated with experimental data obtained from the literature. The kinetic triplet obtained predicts the experimental thermogravimetric curves with an average quality of fit of QOF=2.3%. In conclusion, the Lancones Basin’s pyrolysis behavior is successfully described.

Resumen: Esta investigación caracteriza la cinética de la pirólisis del esquisto bituminoso con potencial en petróleo no convencional de la Cuenca Lancones (Perú). Se aplica la termogravimetría en un medio inerte (nitrógeno) usando tres velocidades de calentamiento (β=5, 10, 20 °C/min) en un amplio intervalo de temperaturas (25 a 800 °C). El triplete cinético se determina usando el método isoconversional de Kissinger-Akahira-Sunose para la obtención de la energía de activación y el factor preexponencial, mientras que con los gráficos maestros se estima el modelo cinético. Los resultados muestran valores de energía de activación promedio de 81.53 y 163.08 kJ/mol y un valor promedio del factor preexponencial de 1.06x107 y 4.07x107 min-1 para los modelos cinéticos de difusión (D1) y contracción cilíndrica (R2). El triplete cinético se valida con datos experimentales obtenidos de la bibliografía. Se demuestra que el triplete cinético obtenido predice las curvas termogravimétricas experimentales con una calidad de ajuste promedio del QOF=2.3%. En conclusión, se describe exitosamente el comportamiento de la pirólisis del esquisto bituminoso de la Cuenca Lancones.

RESUMO O problema tratado é a contaminação da água da Lagoa Yarinacocha por metais pesados e o uso inadequado de resíduos agrícolas. Foi fabricado carvão ativado a partir de cascas de cacau (Theobroma cacao L.) e foi determinado seu efeito adsorvente na remoção de metais poluentes das águas da Lagoa Yarinacocha. A metodologia da superfície de resposta foi aplicada com experimentos fatoriais 33 e 32, com três repetições para otimizar a obtenção do adsorvente e medir sua eficácia na remoção de metais. A modelagem do processo de pirólise, resultou em 17,27 g de carvão ativado a partir de 295,72 g de cascas de cápsulas secas, ótimo com os seguintes parâmetros ótimos: 150 °C como temperatura de ativação, 450 °C como temperatura de carbonização, e 2,5 horas como tempo de modificação. Isto resultou na remoção efetiva de metais poluentes (alumínio: 91,43%, cobre: 75%, ferro: 58,33% e zinco: 58,33%), de amostras de água demonstrando que é possível fabricar carvão ativado a partir de cascas de casca de cacau, com um potencial adsorvente para remover metais das águas da Lagoa Yarinacocha.

ABSTRACT The problem addressed is the contamination of the Yarinacocha Lagoon water by heavy metals and poor use of agricultural residues. It was manufactured activated carbon from cocoa (Theobroma cacao L.) pod husks and determined its adsorbent effect in removing polluting metals from the waters of the Yarinacocha Lagoon. The response surface methodology was applied with factorial designs 33 and 32, with three replicates to optimize obtaining the adsorbent and measure its effectiveness in metal removal. The modeling of the pyrolysis process resulted in 17.27 g of activated carbon from 295.72 g of dry pod husks, optimal with the following optimal parameters: 150 °C as activation temperature, 450 °C as carbonization temperature, and 2.5 hours as modification time. This resulted in effective removal of pollutant metals (aluminum: 91.43%, copper: 75%, iron: 58.33% and zinc: 58.33%), from waters samples demonstrating that it is possible to manufacture activated carbon from cocoa pod husks, with an adsorbent potential to remove metals from the waters of the Yarinacocha Lagoon.

This study proposes a screen of variables that have an influence on the modification of the bio-oil chemical composition as a unique critical quality attribute (CQA) throughout the pyrolytic process (zeolite, ZSM-5) by using a 24 full factorial design, followed by optimization through a response surface methodology (RSM) based on central composite design (CCD) involving samples of biomass sorghum BRS716 (Sorghum bicolor L. Moench). The pyrolysis of pure biomasses and the biomass impregnated with the catalyst was carried out in a vertical bench furnace at 500 °C. Screening design involved factor variation in two levels (-1 and +1) of four variables as critical process parameters (CPPs) such as furnace heating rate (°C min-1), nitrogen flow (mL min-1), amount of biomass (g), and catalyst (% m/m), leading to obtaining bio-oil. Thus, it was possible to create a response surface from these two variables (biomass and catalyst), in which a minimum critical point was reached. The production of a bio-oil rich in hydrocarbon compounds is possible, but a large amount of catalyst was required. Two analytical techniques based on gas chromatography coupled to mass spectrometry (GC-MS) and mid-infrared (MIR) spectroscopy, provided additional information to fully characterize bio-oil chemical composition.