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- Biomass characterization and pyrolysis towards bio-oil productionPublication . Batista, Gabriel de Freitas; Brito, PauloBiomass is considered one of the most promising renewable energy sources in the world, mainly due to its extended availability in rural areas. There are many advantages in using biomass as an energy source, namely its carbon neutrality and being a non-polluting source. In this context, the main technologies for fuel and/or energy production are pyrolysis, gasification, or combustion [1]. 2. Experimental - Biomass sample (pellets) composition was characterized by proximate analysis, determining the fixed carbon, moisture, volatiles and ashes, ultimate analyses, determining the content of C, H, N, S and O. The content of hemicellulose, lignin and cellulose was also determined. The methodologies are described elsewhere [2]. Bio-oil sample obtained by biomass pyrolysis performed in a fixed-bed vertical pyrolysis oven, with a maximum temperature of 500 ºC, a heating rate of 10 ºC/min, a retention time of 0.5 h and a N2 flow of 20 mL/min, was qualitatively characterized using FTIR. 3. Results and Discussion - The results of the biomass characterization are shown in Table 1. It is noteworthy that the pellets have a low value for ashes, being a suitable feedstock for the pyrolysis, as a high concentration of ashes biomass could cause clogging of the equipment during the pyrolysis. According to the ultimate analysis, the average chemical formulation of this biomass would be C1H0.12N0.003O1.03. The yield of the pyrolysis products (wt% basis) was 23.975 %, 28.31 % and 47.15 % for biochar, bio-oil and non-condensable gases respectively. In Image 1, the main peaks observed are the OH vibrations, in the region of 3100 to 3500 cm-1, the peaks between 1650 and 1720 cm-1 relative to the C=O stretching vibrations, the peaks of 1600 and 1450 cm-1 related to aromatic rings, and the peak in the range of 900 to 700 cm-1 is related to substituents of an aromatic ring
- Biomass characterization and pyrolysis, the effect of heating rate on products yieldPublication . Batista, Gabriel de Freitas; Brito, PauloBiomass is widely recognized as one of the main potential sources for renewable and sustainable generation of fuels, chemicals and other carbon-based materials for a long time. According to International Energy Agency, biomass energy accounts for about 14% of the world's total primary energy supply in 2017. There are many advantages in using biomass as an energy source, namely its carbon neutrality and being a non-polluting energy source. Many processes can be used to obtain fuels and chemicals from biomass, and the pyrolysis process is a renewable, economical, and efficient way to produce energy [1]. Pyrolysis is one of the main technologies for biomass conversion into energy. It consists of a thermal decomposition process in an inert atmosphere with absence of oxygen, to convert biomass into biochar (solid fraction), bio-oil (liquid fraction) and gases. Pyrolysis is a recognized industrial process for biomass conversion. No waste is generated in the process, as the bio-oil and biochar can each be used as a fuel and as fertilizer respectively, and the gases can be recycled back into the process [2]. A biomass sample (pellets) was characterized by proximate analysis, determining the fixed carbon (F.C.), moisture, volatiles and ashes composition, and by ultimate analyses, determining the content of C, H, N, S and O. The content of hemicellulose, lignin and cellulose was also determined. The methodologies are described elsewhere [3]. All characterizations were performed on a dry basis, at the conditions in which the sample was previously dried. Pyrolysis tests were performed in a fixed-bed vertical pyrolysis oven, with a maximum temperature of 500 C, a heating rate of 10, 20, 35 and 40 C/min, a retention time of 0.5 h and an N2 flow of 20 mL/min. The bio-oil produced was qualitatively characterized using FTIR
- Assessment of pretreatments for highly concentrated leachate waters to enhance the performance of catalytic wet peroxide oxidation with sustainable low-cost catalystsPublication . Batista, Gabriel de Freitas; Roman, Fernanda; Díaz de Tuesta, Jose Luis; Mambrini, Raquel Vieira; Praça, Paulo; Gomes, HelderMatured compost, derived from a mechanical and biological treatment (MBT) plant, was used as a precursor to produce catalysts through hydrothermal and thermal carbonization, HC and PC, respectively. HC and PC displayed suitable properties to act as catalysts in the catalytic wet peroxide oxidation (CWPO) treatment of the highly polluted leachate waters generated in the same MBT plant (TOC0 = 27 g L-1; COD0 = 60 g L-1; BOD5,0 = 23 g L-1). The influence of catalyst loading and pH were studied, considering multiple additions of H2O2. The best experimental conditions found were T = 80º C, pH0 = 3.0, 7.2 g L-1 of HC catalyst, 85.7 g L-1 of H2O2, added in five batches in one-hour intervals between each addition. Under these experimental conditions, removals of 43%, 52%, 93%, 82%, 35%, 95% and 93% for the COD, TOC, BOD5, aromaticity, chlorides, turbidity and color number (CN) were, respectively, observed. Ion exchange resins and coagulation–flocculation were studied as pretreatment options to reduce the complexity of the leachate waters and enhance the CWPO results. Both strategies resulted in higher mineralization and enhanced the consumption efficiency of H2O2 (H2O2 ). The sequential treatment using coagulation–flocculation and CWPO with PC catalyst showed the best results, achieving abatement of 94%, 70%, 98%, 93%, 31%, 96% and 95% for COD, TOC, BOD5, aromaticity, chlorides, turbidity and CN, respectively.
- Application of compost-derivated carbon catalysts on catalytic wet peroxide oxidation of leachate waters from mechanical and biological treatment plant units for municipal solid wastePublication . Batista, Gabriel de Freitas; Gomes, Helder; Mambrini, Raquel Vieira; Díaz de Tuesta, Jose LuisAlternatives to deal with municipal solid waste (MSW), such as mechanical biological treatment (MBT) plants, are a trend. In these plants, the organic matter is digested by anaerobic bacteria, generating biogas and reducing the solid mass, generating simultaneously a solid compost and a liquid leachate as side-streams. The leachate has a complex composition and cannot be treated by conventional wastewater treatment methods, while the compost is mainly used as an agriculture fertilizer, but the amount produced is higher than its demand. This work deals with the valorization of compost to produce hydrochars and biochars, through hydrothermal carbonization (HTC) and pyrolysis, respectively, with suitable properties to serve as catalysts for the catalytic wet peroxide oxidation of the landfill waters generated in MBT (TOC = 27 g L-1, COD = 60 g L-1, 38.8 mS/cm and 5 g L-1 of chloride ions). Seven catalysts were produced from compost and characterized by several techniques. The catalysts were subjected to screening tests of H2O2 decomposition and the best two were selected to be further studied in the catalytic wet peroxide oxidation (CWPO) of leachate. The experimental conditions of the process, temperature, pH, catalyst load and H2O2 addition were studied seeking optimization. The best experimental conditions found were T = 80 ºC, pH = 3.0, 7.2 g L-1 of catalyst, 85.71 g L-1 of H2O2, added in five batches each hour. Under these experimental conditions, the hydrochar prepared at 230 ºC (HTC-230) achieved removal of 43 % of chemical oxygen demand (COD) and total organic carbon (TOC), turbidity, aromaticity, phenols, chlorides and 5-day biological oxygen demand, (BOD5) removals of 52, 95, 93, 72, 35 and 93 %, respectively. Resins were used to pre-treat the leachate, in order to enhance the CWPO results. Using a cationic adsorption resin (TP-207), considering again operating conditions of T = 80 ºC, pH = 3.0, 7.2 g L-1 of catalyst, 85.71 g L-1 of H2O2, the catalyst HTC-230 achieved 62 %, 55 %, is 97 %, 95 %, 46.5 %, and 97 % for COD, TOC, turbidity, aromaticity, chlorides, and BOD5.
- Evaluation of heating rate on the pyrolysis of residual biomass for biochar productionPublication . Batista, Gabriel de Freitas; Brito, PauloBiochar is a carbon rich solid product of biomass thermal conversion, which contains several properties for a wide range of applications that promote the attention of industries and researchers
- Treatment of leachate waters by wet peroxide oxidation with a compost-based catalyst: effect of pHPublication . Batista, Gabriel de Freitas; Roman, Fernanda; Díaz de Tuesta, Jose Luis; Mambrini, Raquel Vieira; Gomes, HelderA compost-based catalyst was synthesized by hydrothermal carbonization following the procedure described elsewhere1 (3 g of compost in 30 mL of water, 230 °C for 2 h). The material was assessed in the catalytic wet peroxide oxidation (CWPO) of a leachate water, generated during an anaerobic digestion of municipal solid waste. The leachate water is characterized by a high pollutant load (chemical oxygen demand, COD, of 60 g L-1 and total organic carbon, TOC, of 27 g L-1). The CWPO runs were conducted at initial pH (pH0) of 3 and 6, and at the natural pH of the effluent (7.2), Ccatalyst = 1.8 g L-1, 80 °C, and the stoichiometric concentration of H2O2 needed to mineralize the organic content (based on COD). Fig. 1 shows the results obtained along the reaction. An acidic pH (pH0 = 3) resulted in a more controlled, but also incomplete, consumption of H2O2, leading to a low conversion of COD and TOC (20 and 10%, respectively). Contrarily, the natural pH led to a very fast and uncontrolled consumption of the oxidant source, resulting in 100% decomposition of H2O2 in less than 2 h of reaction, but failing to remove COD or TOC (negligible removal, ca. 0%), ascribed to parasitic reactions occurring by the inefficient consumption of H2O2. At pH0 = 6, an intermediate behavior was observed: complete decomposition of H2O2 was possible, at a more controlled rate compared to the natural pH. The result was an increment in COD (41%) and TOC removals (19%), almost two times than that observed at the pH0 3.
- Evaluation of temperature on the pyrolysis of residual biomassPublication . Batista, Gabriel de Freitas; Brito, PauloResidual biomass is considered a critical potential source for renewable and sustainable generation of fuels.
- Evaluation of temperature on the pyrolysis of residual biomassPublication . Batista, Gabriel de Freitas; Brito, PauloOne of the greatest challenges humanity has to deal with nowadays is climate change. In this context, residual biomass is considered a critical potential source for its mitigation, as biomass is a renewable, sustainable and nearly endless available source for the generation of fuels, chemicals and other carbon-based materials. Due to its carbon neutrality, residual biomass is being widely studied, and one of the main technologies for fuel and/or energy production are pyrolysis, gasification, or combustion [1]. Among technologies for biomass conversion, pyrolysis is widely used. It consists of a thermal decomposition process in an atmosphere without oxygen, to convert biomass into biochar, bio-oil and gases, generating no waste during the process [2]. The complexity of biomass pyrolysis arises from the difference in the decomposition of the biomass components combined with the several parameters encompassed on the pyrolysis process. The reaction mechanisms and reaction rates depend on the thermal processing conditions and reactor designs, among those the pyrolysis temperature significantly influences the distribution and properties of the products
- Evaluation of heating rate on the pyrolysis of residual biomass for biochar productionPublication . Batista, Gabriel de Freitas; Brito, PauloBiochar is a carbon-rich solid product of biomass thermal conversion, which contains several properties for a wide range of applications that promote the attention of industries and researchers. The porous structure of char particles enables its application as soil fertilizer, adsorbent, catalyst, among others [1]. In this context, biomass is a critical resource, as it can be used for biochar production at the same time produce renewable energy, being able to mitigate climate change phenomena. There are many advantages to using biomass as an energy source, namely its carbon neutrality and being a nonpolluting source. In this context, the main technologies for fuel and/or energy production from biomass are pyrolysis, gasification, or combustion [2]. Among technologies for biomass conversion, pyrolysis is widely used, consisting of a thermal decomposition process in absence of oxygen, to convert biomass into biochar, bio-oil and gases, generating no waste during the process
- Biomass characterization and pyrolysis towards bio-oil productionPublication . Batista, Gabriel de Freitas; Brito, PauloOne of the greatest challenges humanity has to deal with nowadays is climate change. An important strategy to mitigate climate change is replacing fossil fuels with renewable sources of energy [1]. Biomass is considered one of the world's most promising renewable energy sources, mainly due to its nearly endless availability. Worldwide, each year plants convert approximately 125 gigatons of carbon from atmosphere into biomass, which is equivalent to almost 300 million tons of oil per day [2]. There are many advantages in using biomass as an energy source, namely its carbon neutrality and being a non-polluting source. In this context, the main technologies for fuel and/or energy production from biomass are pyrolysis, gasification, or combustion.