• Energy Research

In this work, chemical and structural properties of various biochars were analyzed and compared with those from a highly stable anthropic soil, Terra Preta de Índio (TPI). TPI is believed to be responsible for the fertility of Amazonian soils and their stability; therefore, the production of a synthetic TPI would be of great interest for agricultural applications. Biochar produced from different raw biomasses were comprehensively characterized and, based on the obtained results, a preliminary study was performed testing three different routes of chemical activation using nitric acid, phosphoric acid, and potassium hydroxide as activating agents. After chemical activations, metal contents in the biochars decreased, as expected, and high degrees of carbonization were observed. In the case of the activation performed with HNO3, intense signals related to carboxylic groups in TG-MS analysis and in potentiometric titrations point out to a highly oxygenated biochar. Structural analysis showed that activations generated point defects in sp2-carbon structures of biochar, with the material obtained after KOH activation showing a high surface area (569 m2 g-1), an important feature for the use as soil amendment.

Abstract The present study aims at evaluating the efficiency of the HZSM-5 zeolite dealuminated with citric acid and modified with sulfated lanthanum oxide (SO42−/La2O3) as catalysts for the production of biodiesel via esterification. The effects of the treatments in the structural, textural and acid properties of produced catalysts were monitored by PXRD, adsorption/desorption of N2 and measurements of acidity by FTIR using pyridine and collidine as probe molecules. The catalysts were tested in the reaction of esterification using oleic acid and methanol as reactants. Different molar ratios (1:10, 1:20 and 1:45) and amounts of catalyst (2%, 5% and 10%) were tested and the conversion of oleic acid into methyl oleate analysed. Results show that the dealumination with citric acid and impregnation of SO42−/La2O3 over HZSM-5 produced catalysts more active for the conversion of oleic acid for the production of biodiesel, when compared to the parent HZSM-5 zeolite. The increase of external surface properties (acidity and area) was the main parameter influencing the activity of the catalysts for the considered reaction.

This work investigated the effects of temperature and of rate of heating on the kinetic parameters of pyrolysis of castor beans presscake, a byproduct generated in the biodiesel production process. Pyrolysis process was investigated by thermogravimetric analysis, and parameters were obtained from nonisothermal experiments. The results obtained from the process of thermal decomposition indicated the elimination of humidity and the decomposition of organic components of the biomass. DTG curves showed that the heating rate affects the temperature of maximum decomposition of the material. Kinetic parameters such as activation energy and pre-exponential factor were obtained by model-free methods proposed by Flynn–Wall–Ozawa (FWO), Kissinger–Akahira–Sunose (KAS), and Kissinger. Experimental results showed that the kinetic parameters values of the FWO and KAS methods display good agreement and can be used to understand the mechanism of degradation of the cake. In a generalized way, the results contribute to bett...

The use of coconut fiber as a copper adsorbent in cachaça was optimised, and changes in the chemical quality of the beverage were observed by analytical techniques. The influence of the adsorbent mass and copper concentration parameters was investigated using the Central Composite Design, and the optimum condition was obtained through the use of Response Surface Methodology. The equilibrium of the adsorption reaction was obtained within 120 min. The kinetic data were better adjusted for the Elovich model (Elovich and Zhabrova 1939) and the isotherm data for the Sips model (Sips 1948). The maximum adsorption capacity was 1.38 mg g-1. Slight changes in the physicochemical quality of the beverage were observed, including a decrease in volatile acidity and alcohol content. Copper levels in cachaça decreased from 8.57 mg L-1 to 4.97 mg L-1 after adsorption. Therefore, the use of biomass as a metal ion adsorbent in beverages can be successfully employed.

La production et l'utilisation du biochar font partie du programme moderne de recyclage des déchets, de rétention des nutriments, des polluants et des métaux lourds dans le sol et de compensation de certaines émissions de gaz à effet de serre. Les biocharges de bois (sciure d'eucalyptus, écorce de pin), de bagasse de canne à sucre et de substances riches en nutriments (enveloppe de café, fumier de poulet) produites à 350, 450 et 750 °C ont été caractérisées afin d'identifier les avantages agronomiques et environnementaux susceptibles d'améliorer la qualité du sol. Les biochars dérivés du bois et de la canne à sucre ont un plus grand potentiel d'amélioration du stockage du C dans les sols tropicaux en raison d'un caractère aromatique plus élevé, d'une concentration élevée en C, d'un faible rapport H/C et des caractéristiques des spectres IRTF par rapport aux biochars riches en nutriments. La teneur élevée en cendres associée à des espèces chimiques alcalines telles que KHCO3 et CaCO3, vérifiée par une analyse par DRX, a fait du fumier de poulet et des biochars d'enveloppes de café des agents de chaulage potentiels pour l'assainissement des sols acides. Des teneurs élevées en Ca et K dans le fumier de poulet et la biomasse d'enveloppes de café peuvent remplacer de manière significative les sources conventionnelles de K (principalement importées au Brésil) et de Ca, suggérant une valeur agronomique élevée pour ces biochars. Les biochars à haute teneur en cendres, tels que le fumier de poulet et l'enveloppe de café, produits à basse température (350 et 450 °C) présentaient des valeurs CEC élevées, qui peuvent être considérées comme un matériau potentiellement applicable pour augmenter la rétention des nutriments dans le sol. Par conséquent, la valeur agronomique des biochars de cette étude est principalement régulée par la richesse nutritive de la biomasse, mais une augmentation de la température de pyrolyse à 750 °C peut fortement diminuer les capacités d'adsorption des biochars de fumier de poulet et de balle de café. Un diagramme du potentiel agronomique et des avantages environnementaux est présenté, ainsi que quelques lignes directrices pour relier les propriétés du biochar avec les utilisations agronomiques et environnementales potentielles. Sur la base des propriétés du biochar, les besoins de recherche sont identifiés et les orientations pour les essais futurs sont définies. La producción y el uso de biocarbón son parte de la agenda moderna para reciclar desechos, retener nutrientes, contaminantes y metales pesados en el suelo y compensar algunas emisiones de gases de efecto invernadero. Los biochars de madera (aserrín de eucalipto, corteza de pino), bagazo de caña de azúcar y sustancias ricas en nutrientes (cáscara de café, estiércol de pollo) producidos a 350, 450 y 750 ° C se caracterizaron para identificar beneficios agronómicos y ambientales, que pueden mejorar la calidad del suelo. Los biochars derivados de la madera y la caña de azúcar tienen un mayor potencial para mejorar el almacenamiento de C en suelos tropicales debido a un mayor carácter aromático, alta concentración de C, baja relación H/C y características de los espectros FTIR en comparación con los biochars ricos en nutrientes. El alto contenido de cenizas asociado con especies químicas alcalinas como KHCO3 y CaCO3, verificado mediante análisis de XRD, hizo que el estiércol de pollo y la cáscara de café biocargaran los posibles agentes calizantes para remediar los suelos ácidos. Los altos contenidos de Ca y K en el estiércol de pollo y la biomasa de la cáscara de café pueden reemplazar significativamente las fuentes convencionales de K (principalmente importadas en Brasil) y Ca, lo que sugiere un alto valor agronómico para estos biochars. Los biochars con alto contenido de cenizas, como el estiércol de pollo y la cáscara de café, producidos a bajas temperaturas (350 y 450 ° C) exhibieron altos valores de CEC, que pueden considerarse como un material potencialmente aplicable para aumentar la retención de nutrientes en el suelo. Por lo tanto, el valor agronómico de los biochars en este estudio está regulado predominantemente por la riqueza de nutrientes de la biomasa, pero un aumento en la temperatura de pirólisis a 750 ° C puede disminuir fuertemente las capacidades de adsorción de los biochars de estiércol de pollo y cáscara de café. Se presenta un diagrama del potencial agronómico y los beneficios ambientales, junto con algunas pautas para relacionar las propiedades del biochar con los posibles usos agronómicos y ambientales. Con base en las propiedades del biocarbón, se identifican las necesidades de investigación y se delinean las direcciones para futuros ensayos. Biochar production and use are part of the modern agenda to recycle wastes, and to retain nutrients, pollutants, and heavy metals in the soil and to offset some greenhouse gas emissions. Biochars from wood (eucalyptus sawdust, pine bark), sugarcane bagasse, and substances rich in nutrients (coffee husk, chicken manure) produced at 350, 450 and 750°C were characterized to identify agronomic and environmental benefits, which may enhance soil quality. Biochars derived from wood and sugarcane have greater potential for improving C storage in tropical soils due to a higher aromatic character, high C concentration, low H/C ratio, and FTIR spectra features as compared to nutrient-rich biochars. The high ash content associated with alkaline chemical species such as KHCO3 and CaCO3, verified by XRD analysis, made chicken manure and coffee husk biochars potential liming agents for remediating acidic soils. High Ca and K contents in chicken manure and coffee husk biomass can significantly replace conventional sources of K (mostly imported in Brazil) and Ca, suggesting a high agronomic value for these biochars. High-ash biochars, such as chicken manure and coffee husk, produced at low-temperatures (350 and 450°C) exhibited high CEC values, which can be considered as a potential applicable material to increase nutrient retention in soil. Therefore, the agronomic value of the biochars in this study is predominantly regulated by the nutrient richness of the biomass, but an increase in pyrolysis temperature to 750°C can strongly decrease the adsorptive capacities of chicken manure and coffee husk biochars. A diagram of the agronomic potential and environmental benefits is presented, along with some guidelines to relate biochar properties with potential agronomic and environmental uses. Based on biochar properties, research needs are identified and directions for future trials are delineated. يعد إنتاج الفحم الحيوي واستخدامه جزءًا من جدول الأعمال الحديث لإعادة تدوير النفايات، والاحتفاظ بالمغذيات والملوثات والمعادن الثقيلة في التربة وتعويض بعض انبعاثات غازات الدفيئة. تم تمييز الفحم الحيوي من الخشب (نشارة الأوكالبتوس ولحاء الصنوبر) وقصب قصب السكر والمواد الغنية بالمغذيات (قشر القهوة وسماد الدجاج) المنتجة عند 350 و 450 و 750 درجة مئوية لتحديد الفوائد الزراعية والبيئية، والتي قد تعزز جودة التربة. يتمتع الفحم الحيوي المشتق من الخشب وقصب السكر بإمكانية أكبر لتحسين تخزين الكربون في التربة الاستوائية بسبب الطابع العطري العالي، والتركيز العالي من الكربون، ونسبة H/C المنخفضة، وميزات أطياف FTIR بالمقارنة مع الفحم الحيوي الغني بالمغذيات. إن محتوى الرماد المرتفع المرتبط بالأنواع الكيميائية القلوية مثل KHCO3 و CaCO3، الذي تم التحقق منه من خلال تحليل XRD، جعل سماد الدجاج والسكريات الحيوية لقشر القهوة عوامل تحديد محتملة لعلاج التربة الحمضية. يمكن لمحتويات الكالسيوم والكالسيوم العالية في روث الدجاج والكتلة الحيوية لقشر القهوة أن تحل بشكل كبير محل المصادر التقليدية للكالسيوم (المستوردة في الغالب في البرازيل) والكالسيوم، مما يشير إلى قيمة زراعية عالية لهذه الفحم الحيوي. أظهر الفحم الحيوي عالي الرماد، مثل روث الدجاج وقشر القهوة، الذي يتم إنتاجه في درجات حرارة منخفضة (350 و 450 درجة مئوية) قيم CEC عالية، والتي يمكن اعتبارها مادة قابلة للتطبيق محتملة لزيادة الاحتفاظ بالمغذيات في التربة. لذلك، فإن القيمة الزراعية للسكريات الحيوية في هذه الدراسة يتم تنظيمها في الغالب من خلال ثراء الكتلة الحيوية بالمغذيات، ولكن زيادة درجة حرارة الانحلال الحراري إلى 750 درجة مئوية يمكن أن تقلل بشدة من القدرات الامتزازية لسماد الدجاج والسكريات الحيوية لقشر القهوة. يتم تقديم رسم تخطيطي للإمكانات الزراعية والفوائد البيئية، إلى جانب بعض الإرشادات لربط خصائص الفحم الحيوي بالاستخدامات الزراعية والبيئية المحتملة. بناءً على خصائص الفحم الحيوي، يتم تحديد الاحتياجات البحثية وتحديد اتجاهات التجارب المستقبلية.

Abstract In this study, the efficiency of citric acid as dealumination agent was evaluated in the case of zeolite HZSM-5 by varying the experimental conditions, namely concentration (0.5, 1.0 and 2.0 mol L−1) and treatment temperature (60 and 80 °C). The effect of the CA treatment on structural, textural and acidity properties of the starting HZSM-5 material was monitored using XRD, N2 sorption and FTIR (pyridine and collidine) measurements. Heptane and methylcyclohexane cracking model reactions were used to evaluate the catalytic behavior of the modified materials, in terms of acid strength and active sites accessibility. The modified catalysts were tested in the esterification reaction, using oleic acid as reagent and different oleic acid/methanol molar ratios. All the results show the beneficial effect of the citric acid treatment on the physicochemical properties of the final materials, with an improvement of the external acidity, a crucial parameter for the reaction considered, i.e. the oleic acid esterification.

Abstract Castor bean (Ricinus communis L.) presscake, a byproduct derived from the biodiesel production process, was used in natura (CN) and thermally treated (CT) form as a natural and low-cost adsorbent for the removal of the dyes malachite green (MG) and tropaeolin (TP). The CN and CT were characterized by elemental analysis, infrared spectroscopy (FTIR), N2 adsorption/desorption and zeta potential. The effects of initial dye solution concentration, adsorbent mass/adsorbate volume ratio, initial pH of dye solution and contact time on MG and TP adsorption were studied using batch-type experiments a 25 °C. The equilibrium adsorption was analysed by Langmuir, Freundlich, Sips, dual site Sips (DSS) and Dubinin–Radushkevich (D–R) isotherms. Kinetics data were evaluated by pseudo-first order and pseudo-second order models. The adsorption data of MG and TP dyes onto CN and CT were best fitted to the dual site Sips model. The maximum adsorption capacities were 37.10, 33.54, 18.60 and 55.98 mg g−1 for the systems MG/CN, MG/CT, TP/CN and TP/CT, respectively. Pseudo-second order gives the better correlation to predict the kinetic process. The thermodynamic aspects were analysed.

Abstract The influence of the amount of SO42−/La2O3 (2–20%) over structural and catalytic properties of HZSM-5 was evaluated. The catalysts were characterized by thermogravimetric analysis, X-ray diffraction, adsorption/desorption of N2 and infrared spectroscopy and they were tested in the esterification reaction of oleic acid and methanol. The influence of the amount of catalyst (2, 5 and 10%) and the influence of molar ratio oleic acid:methanol (1:10, 1:20 and 1:45) were evaluated. The characterization analyses indicated that the starting material had not significant structural and textural changes, but the acidity had changes. The most expressive results of conversion were obtained in the molar ratio 1:10 and 5% of catalyst. The most efficient catalyst was that modified with 10% of SO42−/La2O3 (10OLS/HZ), which presented maximum conversion (100%). In general, the catalysts were efficient. It was possible to observe that most of the modifications produced catalysts more active than the starting material.

Abstract The consumption of pequi generates a considerable amount of waste (peel) which is not used efficiently. Pyrolysis can be a viable alternative for the use of this food waste, by converting pequi peel into energy in the form of biofuels and compounds of great interest to the chemical industry. This study evaluates the potential of pequi peel waste in the production of bioenergy through pyrolysis and characterization of the obtained products. The biomass was characterized and revealed to be a viable raw material for pyrolysis. From thermogravimetry (TG) data, we determined kinetic parameters according to Friedman's global reaction and Flynn-Wall-Ozawa (FWO) models, which led to the mean experimental value of activation energy (Ea) of 239.2 and 224.4 kJ mol−1, respectively. The pyrolysis was carried out at 400, 500 and 600 °C, and the highest bio-oil yield (43.6%) was obtained at 500 °C. The classes of compounds quantified in higher amount in the bio-oils were ketones, furans, acids, alcohols and phenols. The bio-oil compounds from pequi peel pyrolysis can be a source of energy and raw materials of great interest for the chemical industry to produce high-added value products. The biochar shows potential for application as adsorbent and solid fuel. The pyrolysis is a feasible process for the pequi peel waste by adding value and reducing the environmental impact caused by the inadequate disposal of lignocellulosic materials.