•Combustion process of different microalgae was studied by TGA–MS.•Heat released during microalgae combustion was evaluated by DSC.•The kinetic analysis of the combustion process was modelled.•CO, ...CO2 and H2O were the main products obtained together light hydrocarbons (CH4).•Nitrogen compounds were mainly released as NOx, amines and HCN.
The thermal characteristics under oxidizing atmosphere of several species of microalgae: Nannochloropsis gaditana (NG), Scenedesmus almeriensis (SC) and Chlorella vulgaris (CV) was investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) coupled with mass spectrometry (MS). These microalgae were chosen according to their chemical composition. TGA results showed that microalgae combustion took place in two main stages: devolatilization and char oxidation, which were corroborated by DSC analysis. The former one could be related to the decomposition of their main microalgae components: carbohydrates, lipids and proteins. Samples SC and CV yielded the highest amount of ash, which implied that sample pre-treatment such as washing is required before being used in thermal applications in order to avoid operational problems. Sample NG showed the highest amount of combustion heat. Kinetics were evaluated assuming single separate reactions for each combustion stage. Additionally, the process was successfully modeled obtaining for sample NG a maximum error of ±3.1%. CO, CO2 and H2O were the main components obtained during the combustion process. The evolution of CH4 at high temperatures was mainly attributed to lipid decomposition. Finally, it was noticed that nitrogen compounds (NO, NO2 and HCN) were released in a higher proportion that sulfur ones (SO and SO2).
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Pyrolysis, combustion and gasification of solid residues from olive oil processing were investigated. The raw solid residue (RS) contains moisture (21.5%) and residual oil (6.4%). Therefore, from RS, ...raw samples without water (RSWW) and without oil (RSWO) were produced. Thermal analyses of samples were performed at different heating rates over a temperature range of 150-1050 °C. Pyrolysis behavior of the sample was studied in an argon atmosphere, whereas the combustion and gasification studies were conducted in oxygen and steam atmospheres, respectively. The effects of heating rate on the reaction rate and gas evolution were analyzed. Thermal degradation of RS showed that nearly 90% of the conversion occurred at below 700 °C. Gases produced in the three processes mainly consisted of hydrogen, hydrocarbons and carbon oxides. Alcohols and sulfur compounds were also detected in the temperature range of 300 to 500 °C for pyrolysis. Activation energies were determined from non-isothermal multi-heating rate thermogravimetric measurements. The variation in gas evolution was observed between the samples during gasification.
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BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
A series of ferrites (ZnFe2O4, MgFe2O4, NiFe2O4, and CuFe2O4) was prepared by wet air oxidation and their structure and morphology were investigated by X-ray diffraction (XRD) and scanning electron ...microscopy (SEM) analyses. The prepared ferrites were added to flexible poly(vinyl chloride)(PVC) as flame retardants and smoke suppressants. Subsequently, thermal degradation properties of flexible PVC with ferrite additives were investigated by using TGA–DTG, TGA–FTIR, and TGA–MS. The main mechanism underlying the flame-retarding activity was shown to be caused by the catalyzed the dehydrochlorination of PVC at the first stage and breaking of the char residue at higher temperature. The results showed that addition of ferrites, especially MgFe2O4, at the first stage, not only decreased T5% (defined as the temperature at which 5% of the initial weight has been lost) and increased the weight loss rate, but also promoted cross-linking and stability of char residue. The main gas pyrolysis products were HCl and benzene. When compared with neat PVC, PVC/MgFe2O4 and PVC/CuFe2O4 generated more HCl and less benzene, and consequently retained more carbon in the matrix with respect to the increased flame-retarding and smoke-suppressing. At the second stage, the weight loss of flame-retarding PVC increased obviously, with simultaneous increase in the yield of main gaseous pyrolysis products, CO2 and aliphatic fragments. PVC/CuFe2O4 generated a high yield of CO2, because of the cationic cracking reactions in the presence of Lewis acid, fragmenting of the char residue at higher temperature. Additionally, the inner surface morphology of the char residue derived from PVC/MgFe2O4 was investigated by SEM and EDS, which showed the existence of alveolate and breakable structures, as well as needle-like structures, composed of a mixture of iron chloride and magnesium chloride.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Oxy-fuel and air atmospheres were used to (co-)combust sewage sludge (SS) and biomass waste, coffee ground residues (CG) via thermogravimetric analysis (TGA). The combustion behavior of SS did not ...differ significantly in both atmospheres. The replacement of 79%N2 by 79%CO2 significantly influenced the char combustion of CG. Synergistic effect of the blends in the oxy-fuel was weaker than air condition. Activation energy of the co-combustion in the second stage was lower in the oxy-fuel than air atmosphere. The gaseous emissions during blend fuel combustion were investigated by online mass spectrometry (MS). Results show that the gas emissions of different fuels show different stage characteristics. CH3, H2O, C2H2 and NO emissions peaked from the volatiles combustion of CG, while the co-combustion led to SO2 increment. Besides, the composition of the solid residues was examined by X-ray fluorescence spectrometer (XRF), and their impact on environment was evaluated. The compositions of the solid residues pointed to the ability of SS to lower the fouling and slagging risks of CG. This investigation aimed to afford a fully understanding for the co-combustion progress of SS and CG under air and oxy-fuel environments and its implication for environment.
•O2/N2 and O2/CO2 atmospheres were comparatively assessed for (co-)combustions.•Positive synergistic effects were higher in the second than first stage of decomposition.•The difference in Ea in the atmospheres confirmed positive synergies.•The gaseous products were identified using TG-MS.•The slagging characteristics of ashes were determined using XRF.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Different CaCO3 polymorphs were present in the historic lime mortars.•Placement in humid conditions favored the formation of vaterite and aragonite.•Time-dependent transformations hinder the binder ...classification.
The investigation of the chemical composition and physical and mechanical properties of old building materials is relevant for planning restoration interventions and designing compatible restoration materials. The quality of the binders used in mortars determines their durability, and consequently, influences the durability of the building structures in which they are applied. Lime binders continuously undergo chemical alterations as they age. Moreover, weathering agents cumulatively affect their properties, which adds to the difficulty in identifying their original composition. The mineralogy and microstructure of the binders of three historic mortar specimens collected from medieval bridges in the Czech Republic and a mortar designed in the laboratory to mimic the composition of the historic specimens were characterised using thermogravimetry analysis with mass spectrometry, x-ray powder diffraction and scanning electron microscopy coupled with energy dispersive spectroscopy. Two specimens showed binder decalcification and the presence of metastable CaCO3 vaterite and aragonite polymorphs. A mortar of comparable age, which was not exposed to elevated moisture, contained no CaCO3 modification other than calcite.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This study aims to investigate the thermal behaviour of raw and phosphoric acid impregnated olive stones via coupled thermogravimetric analysis-Mass spectrometry (TGA-MS) during pyrolysis. The ...impregnated material was prepared at three H$_{3}$PO$_{4}$/precursor weight ratio of 0.5; 1 and 1.5; for various impregnation time of 3, 6 and 9 h, which was then subjected for thermal analysis. TGA profiles were obtained under dynamic conditions in temperature range 25 °C to 750 °C with a heating rate of 10 °C/min, using pure nitrogen as an inert gas. Thermal degradation of olive stones was observed in three stages namely dehydration, active and passive pyrolysis. Two-steps degradation of raw olive stone occurred, whereas the impregnated material displayed only one step. Addition of phosphoric acid sharply reduced the onset temperature of the main decomposition step. Onset temperatures decreased with increasing rate or time of impregnation. It could conclude that 3 h is sufficient as time of impregnation for activated carbon production. Examination of the main gas products were carried out using coupled TGA-MS. The principal permanent gases detected were H$_{2}$, H$_{2}$O, CO, CO$_{2}$ and the light hydrocarbons C$_{2}$H$_{6}$ and CH$_{4}$. Different kinetic scenarios of raw and impregnated olive stones were observed. The above results should be useful to understand the pyrolysis mechanism of phosphoric acid impregnated olive stone for improving activated carbon production.
Different Me–N–C catalysts for oxygen reduction reaction (ORR) are synthesized using Me(II)-phthalocyanines (Me = Fe, Co, Cu, Zn) as a unique precursor molecule, and SBA-15 silica as a sacrificial ...template. The influence of different transition metals on the pyrolysis process and the consequent physical–chemical properties of the final catalysts were investigated using different characterization techniques such as N2 physisorption, FESEM, EDX, XPS, XRD, and thermogravimetric analysis coupled with mass spectrometry (TGA-MS). The ORR activity and selectivity toward a complete 4-electrons reaction were assessed by RDE analysis in alkaline conditions. The ORR activity of the different Me–N–C catalysts decreases in the order Fe > Co > Cu > Zn ≈ H. Microporosity, pyridinic nitrogen content and temperature at which H2 starts to be detected during the pyrolysis are directly related to the ORR activity of the different catalysts.
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•Me–N–C catalysts for ORR synthesized using Me-phthalocyanines (Me = Fe, Co, Cu, Zn).•SBA-15 silica used as sacrificial template nano-reactor during pyrolysis.•Different metals influence the physical–chemical properties of Me–N–C catalysts.•ORR activity in alkaline medium decreases in the order Fe > Co > Cu > Zn ≈ H.•Micropores, pyridinic-N and pyrolysis de-H2 temperature linked to the ORR activity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Tetrabromobisphenol-A (TBBA) is the most common brominated fire retardant. In this study, a TBBA containing paper laminated printed circuit board (PCB) prepared from novolac was pyrolysed by both TGA ...and in a quartz glass reactor between 40 and 1000
°C. The products were online detected by MS. It was found that the PCB degraded in three steps. Step one (<270
°C) consisted of the evolution of water and CO
2 from the paper laminate. In the second step, between 270 and 370
°C, the fire retardant decomposed, releasing HBr and brominated aromatics. In the third step, at temperatures above 370
°C, the phenol resin decomposed and char was formed. Compared to pure TBBA, which mainly produces brominated phenols, the brominated products enclosed in the char released HBr during the last degradation step as well as during the second step. Most of the bromine left the resin in the form of HBr, with about 14% of the bromine being fixed in brominated aromatics and less than 2% remaining in the residue.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
•Co-gasification process of olive pomace, coal and petcoke were carried out.•The reactivity of raw materials, binary and ternary blends were examined.•Gaseous products released during the process ...were evaluated by TGA-MS.•Synergistic or antagonistic effects of binary and ternary blends were evaluated.•Morphology of remaining residues on the gasification process were analysed by SEM.
A comparison of the gasification performance of olive pomace, coal, petcoke and their binary and ternary blends was carried out by means of TGA (thermogravimetric analysis) coupled with mass spectrometry (MS). The thermochemical behavior of the raw materials was a function of their composition and inorganic content. Olive pomace had a low ash content, a high volatile content and a low moisture. Moreover, olive pomace presented the highest reactivity. On the other hand, olive pomace presented the highest H2, CO, CO2, CH4 and NO emissions, while the highest SO2 release was obtained with petcoke, showing the output stream coming from the gasification of coal the highest H2/CO ratio. The presence of olive pomace in the blends improved their reactivity, increased the H2 release and the H2/CO ratio, and decreased the CO yield. A synergistic effect was observed in the gasification of the binary blend of olive pomace and petcoke. On the contrary, the gasification of the binary blend of olive pomace and coal presented an antagonistic effect. In ternary blends, either ssynergistic or antagonistic effects were observed, which depended on raw materials ratios in the feed. Finally, the lower the olive pomace ratio in the blends, the higher the porosity of the remaining residue was.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPUK, ZRSKP
Abstract
The amount of food waste that is generated all over the world is enormous. As food wastes are rich in nutrients and organics, they serve as a potential source for the generation of many ...value-added commodities and energy. In most countries, food wastes are predominately dumped in open lands or incinerated, along with other combustible materials such as municipal solid wastes, for the possible extraction of energy. However, these two modes of food wastes disposal are encountering more and more environmental, technical, and economical challenges. More recently, it has been realized that food wastes can be transformed into energy and value-added products, such as horticultural biochars, using thermochemical technologies such as pyrolysis and gasification. In the current research work, three selected food items, carrots, cucumbers, and tomatoes, have been studied using thermogravimetric analysis. The biochar analysis involves one single food item (carrot), one binary mixture (carrot + cucumber), and one ternary blend of carrot, cucumber, and tomato. Two heating rates were used in order to perform kinetic modeling studies using the Arrhenius and Coats-Redfern models. Since the production of the pyrolysis gases—for energy and chemicals production—is of major economic significance regarding the overall process viability, the TGA syngas for a single component, binary component and tertiary component systems were analyzed by TGA coupled mass spectrometry. The results of the gas analysis indicate an increase in hydrogen generation due to blending the food wastes.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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