In Indonesia, starch, particularly that obtained from bengkuang (Pachyrhizus erosus), is abundant and inexpensive, thereby increasing the value of bengkuang starch, which can be mixed with ...bioplastic-based starch. A biocomposite comprising nanocellulose from water hyacinth (Eichhornia crassipes) and bengkuang starch was successfully fabricated using the solution casting method. Nanocellulose content in the matrix was kept constant at 1wt%. Moreover, during fabrication, the biocomposite gel was treated in an ultrasonic bath for 0, 15, 30, and 60min. Further, thermogravimetric analysis, moisture absorption measurements, Fourier transform infrared spectroscopy, and scanning electron microscopy were performed. The biocomposite sample vibrated for 60min had the highest thermal stability and exhibited low moisture absorption. The soil burial test proved that this biocomposite, as opposed to 0-min vibrated samples, has a slower biodegradation rate. This result was supported by morphological evaluation after biodegradation, in which the 60-min vibrated samples showed a coarse surface and low porosity formation.
•Horse manure is thermogravimetrically analysed at 1–10 °C/min under inert environment.•The TGA data is analysed using model-free FWO, KAS, Friedman and Kissinger methods.•The determined activation ...energy for horse manure is between 149 and 200 kJ/mol.•Horse manure shows highest conversion rate at pyrolysis temperature of 290–330 °C.•FWO, KAS and Friedman methods are reliable in determining the kinetic parameters.
Horse manure is a biowaste with bioenergy recovery potential for heat and power generation. However, there is no kinetics data in literature to date. In this work, a kinetic study of the pyrolysis process of horse manure is investigated through the use of thermogravimetric analyses. The samples were heated over a range of temperature from 298 to 927 K with four different heating rates of 1, 2, 5 and 10 K/min. The weight loss was measured by a thermogravimetric analyser in an inert atmosphere. The differential thermal gravimetric (DTG) thermogram shows that the highest reaction rate occurred at between 290.2 and 329.6 °C where the devolatilisation process was initiated to overcome the activation energy barrier of the manure. The activation energy and pre-exponential factor obtained by the Kissinger method, assumed to be constant throughout the whole pyrolysis process are 149 kJ/mol and 3.3 × 1012 s−1, respectively. The activation energy calculated from the non-isothermal Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) and Friedman methods are 199.3, 200.2 and 194.6 kJ/mol, whereas the pre-exponential values are 9.3 × 1018, 1.8 × 1019 and 3.6 × 1020 s−1, respectively. The kinetic parameters determined based on interval conversional fraction shows good agreement. The high volatile and low ash content in horse manure indicates the potential for bioenergy recovery. The results of the kinetic study can be used for modelling devolatilisation and designing thermochemical conversion processes.
•Characterized temperature of pyrolysis was studied by conversion curvature•Activation energy of lignin was underestimated in three parallel reaction model•Three parallel reaction model is inaccurate ...to estimate characterized temperatures•Kinetic study using parallel finite number first-order reaction model is reliable
In this work, the pyrolysis behaviors and kinetics of two bamboo (Bambusa texlitis) wastes were investigated via thermogravimetric analysis. The weight loss behaviors of pyrolysis were studied by curvature of the conversion (α) curves. The curvature of α can depict the characteristic temperatures of pseudo component (hemicellulose, cellulose and lignin) pyrolysis. Model-free model was applied to estimate the apparent activation energies of the pure components for comparison with other kinetic models. Three parallel reaction (TPR) and parallel finite number first-order reaction (FNFOR) models were used for kinetic studies. The first-order TPR model underestimates the apparent activation energies of pseudo components. The nth-order TPR model underestimates the apparent activation energy of lignin and obtains characteristic temperatures that are inconsistent with those of pure lignin. The parallel FNFOR model is more reliable for simulating the kinetics of lignocellulosic biomass pyrolysis. The apparent activation energies of pseudo components depend on the variety of lignocellulosic biomass.
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•Coal and biomass samples have been experimentally characterized by TGA and DSC.•Combustion and oxy-combustion behaviours are assessed and kinetically analysed.•Kinetic analysis is ...based on both FWO and KAS methods and results are compared.•Oxy-combustion can improve the burning rate of fuels, shortening the burning time.•Both FWO and KAS are reliable for combustion, but only for coal for oxy-combustion.
This paper reports on the results of air-blown combustion and oxy-combustion kinetic characterization (comparing two different isoconversional methods: Flynn-Wall-Ozawa and Kissinger-Akahira-Sunose) of different kinds of coal (from Italy, South Africa and Hungary) and biomass (pine and eucalyptus chips) by thermogravimetric analysis (TGA) and differential scanning calorimeter (DSC) together with the assessment of different characteristic combustion parameters. It can be observed that the burning rate of fuels can be improved by the oxy-combustion process, shortening the burning time (a mean reduction of the burnout time of 14% and 22% can be observed for coal and biomass samples, respectively). Moreover, biomass shows better ignition performance than coal and enhances combustibility indexes (S and Hf), especially in oxy-combustion conditions. For example, the S index, which reflects combustion properties, increases by an order of magnitude for biomass combustion and oxy-combustion with respect to coal values, thus indicating a higher combustion activity for biomass; an opposite trend can be observed for the Hf index, which describes the rate and intensity of the process and is lower for biomass than for coal, thus indicating better performance for wood chips combustion. Kinetic analysis shows that the activation energy Ea varies with conversion values, reflecting the kinetic complexity in both the processes. Moreover, with the same range of heating rates (10 ≤ β ≤ 50 °C/min) and for the overall range of conversion (0.1 ≤ α ≤ 0.9), both of the models used fit the experimental data in combustion regime, whereas the increase of the oxygen concentration makes the results reliable for coal samples and more sensitive to weight loss for biomass samples.
•The state of the art in thermal degradation mechanism of PLA/PHB blends is discussed.•The impact of different fillers and additives on the thermal stability of PLA/PHB blends is reviewed.•The ...influence of the processing on the thermal stability of PLA/PHB blends is evaluated.•The mechanisms underlying the degradation for PLA and PHB are described and compared.
Polylactic acid (PLA) and polyhydroxybutyrate (PHB) are two biopolyesters obtained from renewable resources like corn or sugar under bacterial fermentation. PLA is the most widely used biopolymer in diverse applications. Addition of PHB to PLA can improves the crystallinity of PLA, and thereby its mechanical strength. However, both PLA and PHB suffer from poor thermal stability, which limits their potential industrial application. The purpose of this review is to explain thermal decomposition behavior and mechanism of these polymers and systematically categorize available reports on thermal degradation of the neat PLA and PHB, and also as-processed PLA/PHB blends along with PLA/PHB blends modified/reinforced with plasticizers, additives or crosslinkers. The characteristic temperatures (Tonset, and peak temperature or Tmax) of PLA and PHB are taken as the key parameters governing thermal degradation behavior of PLA/PHB blends and composites with variable composition. From this survey we can conclude that the thermal stability of PLA in PLA/PHB blend is lower than the neat PLA, contrary to the PHB with higher thermal stability in PLA/PHB blend. Therefore, thermal degradation mechanism of PLA/PHB blends must be taken as a complex physico-chemical phenomenon. Moreover, the selection of additive severely affects the thermal stability of PLA/PHB blends. Processing method and localization of additive in different phases or at the interface of the phases are factors determining the ultimate thermal stability of blend.
An emerging technology of CO2 sequestration in Portland cement (PC) is through accelerated carbonation, where PC is intentionally carbonated at early hydration age and reinitiates long-term hydration ...upon completion of carbonation. However, the current literature has overlooked a fact that different PC hydration ages prior to carbonation (pre-hydration) could lead to distinct carbonation efficiencies and subsequent hydration behaviors (post-hydration). Here, we examine the effects of length of pre-hydration period on CO2 uptake and on the hydration extent and final strength at 28 days. The CO2 and H2O profiles in the carbonated PC were examined with thermogravimetric analysis/derivative thermogravimetric analysis. The pre-hydration path was traced with isothermal calorimetry. Experimental results suggested that extension of pre-hydration decreased CO2 uptake, but enhanced the extent of PC hydration at 28 days. It was found that a pre-hydration beyond the late deceleration period of PC hydration (where heat generation is slowing down) led to a higher hydrate content of cement paste, hence forming a higher compressive strength of mortar compared to the noncarbonated benchmarks at 28 days. The lesser carbonation-induced water loss and the nucleation seeding enabled by calcium carbonate are likely responsible for this effect. The finding reported here should be useful for fine-tuning PC carbonation process for CO2 sequestration in concrete.
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•Oxy-fuel combustion behaviors of semi-coke and bituminous coal are analyzed.•Semi-coke burnout behavior is largely improved when N2 is replaced by CO2 at 21%O2.•Kinetic parameters by ...the Starink and the Malek methods are obtained for the blends.•Activation energies of the blends increase with the increased oxygen concentration.•Mechanism functions are more prone to change with the conversion degree over 0.55.
Semi-coke is blended with bituminous coal in oxygen-enriched atmospheres to be efficiently used as an energy source. Combustion characteristics and kinetic behavior of blends under oxygen-enriched atmosphere are studied with thermogravimetric analysis. The ignition temperature of each sample in 21%O2/79%CO2 atmosphere is about 15 °C higher than that in air. The burnout behavior of semi-coke is significantly improved when N2 is replaced by CO2 at the same oxygen concentration. Increasing oxygen concentration can improve ignition and burnout behaviors further. Differential thermogravimetry (DTG) curves of semi-coke show quite different behaviors in air and 21%O2/79%CO2 atmospheres. There are two distinct peaks in air, while in 21%O2/79%CO2, there is only one. Activation energies of blends are obtained by Starink method at four heating rates. These activation energy values are, then, used to determine the most probabilistic mechanism function of each stage by Malek method. The results show that the activation energy usually decreases with the increase of the conversion degree and the proportion of bituminous coal. The average activation energy in air atmosphere is slightly smaller than that in 21%O2/79%CO2 atmospheres. It is worth noting that the activation energies of the blends increase with the increase of oxygen concentrations.
Thermogravimetric analysis (TGA) is a quantitative analytical technique that monitors the mass of a sample from 1 mg to several g as a furnace ramps temperature to as high as 1600°C under a stable or ...changing gas flow. The first gravimetric test was in 27 BC when Vitruvius measured limestone's change of mass as it calcined to lime. In modern chemical engineering, researchers apply the technique to derive conversions, kinetics, and mechanisms for any process with a change of mass by isothermal, non‐isothermal, and quasi‐isothermal methods. The mass drops as the sample decomposes, volatile compounds evaporate, or the oxidation state decreases, while in reactive environments (with O2, for example), the mass of transition metals may increase. TGA is incapable of detecting phase transitions, polymorphic transformations, or reactions for which mass is invariant. DSC or DTA couple with TGA to help deconvolute a DSC plot by separating physical changes from chemical changes. Evolved gas analysis techniques monitor the gaseous products exiting the TGA furnace on‐line as the temperature ramps. A bibliometric map of keywords from articles citing TGA indexed by Web of Science in 2016 and 2017 identified five research clusters: nanoparticles, performance, and films; crystal structures, acid, and oxidation; composites, nanocomposites, and mechanical properties; kinetics, pyrolysis, and temperature; and adsorption, water and wastewater, and aqueous solutions. This review provides an overview of the basic principles of modern TGA.
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•Co-pyrolysis of 50% textile dyeing sludge (TDS) had the most positive interaction.•The n-order mechanisms best explained the main devolatilization stages of ...co-pyrolysis.•Co-pyrolysis produced more hydrocarbon products and reduced CO, SO2 and NOx.•Co-pyrolysis promoted the further decomposition of ketones and aromatic compounds.•Co-pyrolysis of TDS and polyurethane tires enhanced char aromaticity.
The massive industrial wastes of textile dyeing sludge (TDS) and waste shared bike tires are becoming increasingly problematic environmentally and economically. Their co-pyrolysis maybe an affordable and eco-friendlier alternative so as to reduce their waste volumes and emissions, as well as recover value-added oils and chars. This study was the first to characterize the TDS co-pyrolysis with rubber (RT) versus polyurethane (PUT) tires and their performances, mechanisms, emissions, oils, and chars as a function of temperature and blend type and ratio. The co-pyrolysis increased the total weight loss from 51.76% with TDS to 55.30% with 50% TDS and 50% RT (TR55) and to 68.92% with TP55. TR55 and TP55 yielded the best performances, with the stronger synergistic effect with the TP than TR co-pyrolysis. The optimal reaction models were second-order (F2) and five-dimension diffusion (D5) for the two devolatilization sub-stages for TDS, two thirds-order (F1.5) for the TR55 and the second and fourth sub-stages of the TP55, and F2 for the first and third sub-stages of the TP55. The co-pyrolysis reduced emissions of CO, SO2, and nitrous compounds, did not change their temperature dependency, and produced more hydrocarbon products. The TR co-pyrolysis produced more D-limonene and isoprene and inhibited the isomerization of D-limonene. The TP co-pyrolysis further decomposed diaminodiphenylmethane into low-molecular weight benzene series such as toluene and styrene. The co-pyrolytic chars had higher branching degree of aliphatic side chain and bridge bond, with the TP ones having the enhanced char aromaticity.
Abstract The article describes the results of comprehensive laboratory tests of mine dust samples taken from active mine faces in the Kuznetsk coal basin (Kemerovo region, Russia). The purpose of the ...experiments is to study the characteristics of thermal destruction processes in mine dust depending on its mineral composition. Based on the results of electron microscopy, the mineral composition of the dust samples under study was determined, and the quantitative relationships of the mineral phases composing the sample were assessed. Using thermogravimetric analysis the lower limits of thermal destruction intervals were established for samples of mine dust with different compositions and percentages of mineral inclusions. The practical significance of the results obtained is substantiated.
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