Thermogravimetric Apparatus Research Articles

Reducing the Energy Consumption during Microwave Drying of Coal Slime Dough by Optimizing Parameters: Experiment and Modeling.

Reducing the energy consumption in microwave drying processes is essential for the sustainable management of coal slime. Utilizing a self-constructed microwave thermogravimetric apparatus, the research investigates critical parameters, including microwave power, spherical diameter, and granule size, affecting drying kinetics and energy efficiency. The results show that it was observed that the drying process progresses through three distinct stages, marked by variations in temperature and moisture content: the initial warming phase, a steady drying stage, and a final phase where the drying rate decreases; optimal pellet sizes for efficient moisture evaporation and diffusion were identified, with smaller particles enhancing heat transfer and drying efficiency; and the Nadhari model was determined to best represent the drying kinetics of coal slime under microwave radiation. The findings indicate a positive correlation between drying efficiency and particle size while being inversely related to increased microwave power for smaller granules. A direct positive relationship between moisture migration and increased power levels was established, while an inverse relationship with the enlargement of particle sizes was observed, negatively affecting the efficiency. For granule sizes of 30, 40, and 50 mm, a decrease in activation power was recorded, with values of 8.215 ± 2.301, 7.936 ± 1.547, and 3.393 ± 0.248 W·g-1, respectively; and through the comparative analysis of energy consumption, it was demonstrated that for coal slurry particles sized 0.15-0.18 mm subjected to a drying duration of 600 s, an increase in power leads to a reduction in drying efficiency, whereas larger diameter contributes to improved efficiency.

Effect of the matrix volume fraction on the oxidation resistance of porous CVI-processed C/C composites

The correlation between the amount of chemical vapor infiltrated matrix inside porous C/C composites and their resistance to oxidation was investigated. Three C/C samples with homogeneous matrix fractions from 17% to 59% were oxidized in a thermogravimetric apparatus where a diffusion-control regime was reached. The results showed that the materials effective kinetics are proportional to their initial geometric density. With a tripled matrix content, the recession rate dropped by 50% and the depth affected by oxidation fell by 34%. A high matrix fraction was proved to favor the smallest pore sizes and to increase the tortuosity of the diffusion paths.

Stabilization time and temperature influence on the evolution of the properties of mesophase pitch stabilized fibers and carbon fibers

The structure of a mesophase pitch carbon fiber is primarily developed during the fiber spinning process and is refined in stabilization and carbonization steps. Stabilization of mesophase pitch filaments was performed in a thermogravimetric apparatus (TGA) using a multivariate approach to investigate the influence of the initial and final temperature of stabilization and the step time on the changes that occur during the stabilization stage. Different levels of stabilization were observed: insufficient, proper, and over-oxidation. Through Fourier Transform Infrared Spectroscopy (FTIR), Energy-Dispersive X-ray Spectroscopy (EDX), and X-ray Photoelectron Spectroscopy (XPS), it was found that the chemical composition of the stabilized fibers was highly dependent on the mass evolution of this thermal treatment. Excessive stabilization induced defects in the structure of the fibers that negatively reflected on their tensile strength and modulus. Stabilization at lower final temperatures led to low mass increase but in turn provided carbon fibers with the highest modulus. Carbon fibers differing solely in their initial stabilization temperature did not exhibit statistically different tensile strength and modulus, proving that industrial stabilization can be shortened without compromising the fibers' properties.

Designing porous C/C composites for oxidation resistance with an analytical model based on the kinetic and architectural features of fibers and matrix

Carbon/Carbon composites used in rocket propulsion contain many process-related pores and have a porosity-dependent oxidation recession rate. A 1D analytical model has been developed to describe this behavior and assess the structure-reactivity relationship for the oxidation of such composites. The model has been compared to experiments for validation. Oxidation experiments have been carried out using samples featuring individually different matrix fractions in a thermogravimetric analysis apparatus under dry air. Post-test morphologies were characterized with X-ray micro-computerized tomography and a 3D-image correlation technique. Finally, guidelines are given for the design and optimization of porous C/C composites with respect to oxidation resistance.

Lead-acid batteries (LABs) and the thermogravimetric analysis of Pb metal reduction from PbO2 via microwave heating at 2.45 GHz

The lead (Pb) in lead-acid batteries (LABs) accounts for up to 60% of their total weight and 80% of the metallic Pb produced worldwide. As a toxic substance but sought-after resource, developing a method to reclaim Pb from spent batteries, both safely and efficiently, is highly desirable. To this end, this paper explores the application of microwave heating to reduce Pb from PbO2, a component of LAB pastes, using a carbon (C) reductant. Various experiments were conducted between 200 and 1000 W to determine mass loss kinetics using a homemade thermogravimetric apparatus. The mechanisms and kinetics of the reactions, and their resultant phases, are discussed in comparison to differential thermal analyses (TG-DTA) of the same samples. Microwave heating was found to be highly effective, resulting in up to a 97% recovery of Pb metal at < 300 °C; however, complete reduction was unrealized due to crucible interference, microwave penetration depth, and the reflection of microwaves as Pb metal formed. The reduction and decomposition reactions were evaluated using X-ray diffraction (XRD).

Green coal substitutes for boilers through hydrothermal carbonization of biomass: pyrolysis and combustion behavior

Hydrothermal carbonization (HTC) is a thermochemical conversion process in aqueous phase that is well suited for the valorization of waste biomass. The carbonaceous solid phase produced by the HTC process (the so-called hydrochar) shows interesting properties that make it similar to conventional solid fuels. Thus, it may be used in existing coal-handling infrastructures, rendering it particularly attractive for co-firing. Two different biomasses are investigated: walnut shells as biomass richer in lignin, and miscanthus as biomass richer in hemicellulose/cellulose. The properties of the resulting hydrochars are analyzed and compared with those of untreated biomass and of coals typically used in industrial boilers. The HTC treatment results in the reduction of the cellulose/hemicellulose contribution and O/C ratio, and in an increase of aromatic structures, heating value and grindability. The behavior of the hydrochars upon pyrolysis under fast heating conditions typical of pulverized fuel boilers is investigated using a heated strip reactor (HSR). The combustion reactivity tests in a thermogravimetric apparatus show that the HTC treatment levels off the differences between various biomasses, while the HSR treatment generates chars with the same combustion reactivity as char obtained from coal erasing the differences between HTC-derived biomass and fossil fuels. As for char reactivity, the HTC process reduces the impact of the different biomass compositions on tar formation, but few differences are still observed regarding the volatile phase between biomass hydrochar and coal samples. Results are analyzed and discussed with the goal of evaluating the potential of HTC of lignocellulosic biomass to generate green fuels suitable for industrial boilers.

Mechanical and Thermal Adsorption Actions on Epoxy Hybrid Composite Layered with Various Sequences of Alkali-Treated Jute and Carbon Fibre

Structural applications are accomplished by using a lightweight epoxy matrix bonded with natural jute fibre/synthetic carbon fibre to enhance the physical, mechanical, and thermal properties obtained by different sequences of alkali-treated jute fibre (J.F.)/carbon fibre (C.F.) through conventional hand layup technique. The sequences of the sample are named as H1, H2, H3, and H4 layers of JF/JF/JF/JF, CF/CF/CF/CF, JF/CF/CF/JF, and CF/JF/JF/CF. Influences of JF/CF on physical, mechanical, and thermal adsorption properties of the epoxy composite are evaluated and compared. The mechanical tensile performance of the jute fibre-covered (JF/CF/CF/JF) composite H3 sample is augmented by 29% compared to the H4 sample. Similarly, the CF/JF/JF/CF combinations exhibited a higher impact strength of 129.71 KJ/m2. The maximum hardness of 47.12Hv was found on the four-layered carbon fibre. The thermal adsorption actions on developed composites are evaluated by thermogravimetric apparatus (TGA). It is confirmed that the presence of JF/CF in epoxy composites can endure stability at a higher temperature.

Thermal Adsorption and Mechanical Behaviour of Polypropylene Hybrid Composite Synthesized by Glass/Hemp Fibre via an Injection Moulding Process

Thermoplastic-based polymers are gathering importance in several engineering fields like electrical, electronic, automotive, aerospace, and structural. The additions of secondary phase reinforcements such as natural and synthetic fibre improve thermoplastic-based polymer’s properties. The thermoplastic and natural fibre combinations are found to have low mechanical strength and incompatibility and need special treatment for synthesizing the natural fibre. The present experimental investigation deals with the enhancement of polypropylene hybrid composite by using the combinations of glass (synthetic)/hemp (natural) fibre for the ratio of 0 : 35, 5 : 30, 10 : 25, and 15 : 20 reinforced with 5 wt% compatibilizer through injection moulding. The revealed test results of polypropylene hybrid composite showed improved mechanical impact and flexural and tensile strength of 37.5%, 14.2%, and 21.1%, respectively. The thermal adsorption characteristics were evaluated by thermogravimetric analysis apparatus. It showed the decomposition of composite limited by hemp fibre at 27°C to 700°C.

Optical and laser damage properties of 98% deuterium DKDP crystal in different crystal orientations

Served as electro-optic switch, frequency converter and the optical parametric chirped pulse amplifier (OPCPA), highly deuterated DKDP crystals are critical optical elements in high power laser systems. In our work, samples taken in Z direction and Ⅰ-type phase-match direction from an as-grown high deuterium DKDP crystal, which was grown by the rapid growth method with continuous filtration. Thermo-gravimetric apparatus (TGA) measurement was applied to obtain the deuterium content of the DKDP crystal. the results showed the deuterium level of the samples in our experiments exceeded 98%. The ultraviolet–visible–near-infrared transmittance spectrum showed that the transmittance of Z-cut at 532 nm and Ⅰ-type at 1064 nm were 92.99% and 96.07%, respectively. The 0% laser-induced damage threshold of Z-cut in 1064 nm was about 40J/cm2, exceeding much more than the application requirement in certain high power laser systems. The polarization state of laser had little effect on the laser-induced damage characteristics of Ⅰ-type sample. Then the laser-induced damage morphologies of 98% DKDP crystals induced by the 1064 nm and 532 nm lasers were investigated. The results indicated that the "micro-explosion" of different kinds of defects in the bulk led to different damage morphologies, and many cracks in the damage pinpoints presented the regular orientation with better consistency in view of the Ⅰ-type phase-match direction. Our research can provide a reference for the applications of highly deuterated DKDP crystals in high power laser systems.

Combustion ash addition promotes the production of K-enriched biochar and K release characteristics

Biogas residues (BR) and maize silage (MS) from biogas plants were mixed with biomass combustion ash (ASH) for K-enriched biochar preparation. The characteristics and nutrient contents of biochar were determined by thermo-gravimetric apparatus, Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscope, and chemical extraction methods, respectively. The desorption kinetics and slow release mechanism of K in biochar were evaluated after an incubation experiment for 28 days. Results showed that biochar yields were improved from 36.6% to 49.0% for BR-based biochars (BRCs) and 24.9%–38.2% for MS-based biochars (MSCs) with the addition of ASH during pyrolysis. The total potassium (TK) content of composite biochar increased to the highest TK content of 37.29 mg/g in biochar derived from MS with 20 wt% ash (MSCA20%). Furthermore, slow-available K content increased from 0.86 mg/g and 1.62 mg/g of primary biochar derived from BR and MS to 6.88 mg/g and 7.8 mg/g in composite biochar with 20 wt% ash respectively. The formation of K–Si–Al–O species involved unstable clay minerals and stable insoluble minerals during the catalytic pyrolysis improved slow release performance. The composite biochar showed a slower and continuable K+ release property in the incubation experiment, releasing less than 80% of the total available K into water in 28 days. The K+ desorption kinetics fitted the Power function well, indicating release of K+ was a complex reaction process. This lab-scale work showed that the pyrolytic composite biochar from wastes in biogas plants with combustion ash addition has the potential to be slow release fertilizer. The combined thermal conversion of solid wastes provides a sustainable strategy to simultaneously achieve the reclamation of nutrients and generation of environmental benefits via the production of biochar fertilizer.

A comprehensive study on the oxidative pyrolysis of epoxy resin from fiber/epoxy composites: Product characteristics and kinetics

Thermal treatment has been the most feasible process to recycle valuable carbon fibers and obtain fuel and chemicals from waste fiber/epoxy composites. The present work studied the oxidative pyrolysis behaviors of epoxy resin from fiber/epoxy composites using a thermogravimetric apparatus and a fixed-bed reactor, respectively. The effects of various O2 concentrations on the thermal behaviors of epoxy resin were investigated and the product characteristics were analyzed. Furthermore, a multi distributed activation energy model (multi-DAEM) was first developed to determine the oxidative pyrolysis kinetics of epoxy resin under various atmospheres. Results showed that the degradation behaviors of epoxy resin were largely altered by the O2 concentrations. High O2 concentrations accelerated the primary decomposition of epoxy resin and shifted the oxidation of resin residue into lower temperatures. High contents of methylcyclohexene and phenolic derivatives were detected in liquid products. In air atmosphere, high yields of CO and CO2 were generated and distributed in several stages. The kinetic analysis indicated that the multi-DAEM method can well explain the oxidative pyrolysis behaviors of epoxy resin. A minimum six-reaction fitting process can perfectly simulate the oxidative pyrolysis of epoxy resin. The predictions for various O2 concentrations were in good agreement with the experimental tests.

DETERMINATION OF THE SUITABILITY OF OIL PALM FIBRE COMPOSITE FOR BUILDING APPLICATIONS BY CONE CALORIMETER AND THERMAL ANALYSIS

The high yielding of oil pam fibre reinforced composite (OPFC) to fire has necessitated research to improve and develop fire retardants (FR) to mitigate the spread of fire. Researchers relied on Flame Retardants (FR) classified as either halogenated or non-halogenated based FR to improve the performance of composites with emphasis on flammability properties (FP). The main object of this paper is to evaluate the effect of six non-halogenated FR species in OPFC to meet required fire safety standards for building purposes. The six FR species comprising aluminum tri-hydroxide (ATH), ammonium polyphosphate (APP), Gum Arabic powder (GAP) and carbon black (CB) were processed with OPFC at 0, 15 and 18% loading ratio using hand lay-up compression moulding technique. Specimens cut from the OPFC panels were tested for flammability and thermal properties using thermogravimetric analysis (TGA/DSC Metlar Toledo) and cone calorimeter apparatus respectively. The result obtained for thermal analysis shows that the panel was thermally stable at 391.6OC before degradation began compared to those without FR while peak flammability properties obtained for heat released rates, mass loss rates and smoke production rates showed the OPFC panels rapid fire response were significantly reduced respectively by 67.4%, 50.9% and 37.5% compared to those without FR. It can be concluded that the hybrid FR comprising APP-GAP showed a stable char structure during fire and thus prevented the escape of combustible volatiles which reduced the peak FP values of the OPFC panels. These flammability properties could be said to meet required fire safety standards for building applications.

Regeneration reaction characteristics and mechanism model of K2CO3/Al2O3 sorbent for CO2 capture

AbstractThe regeneration reaction characteristics of the K2CO3/Al2O3 sorbent were investigated with a thermogravimetric apparatus. The effects of the gas composition and temperature on the regeneration conversion and reaction rate were analysed extensively. The results of the thermogravimetric experiment revealed that the regeneration characteristics of K2CO3/Al2O3 are better than those of pure K2CO3 and that temperature is the key parameter for the K2CO3/Al2O3 regeneration process. It was also observed that the regeneration process of K2CO3/Al2O3 occurred in three stages. As the regeneration temperature increased, regeneration occurred in the following sequence: KHCO3 on the external surface, KHCO3 on the internal surface and KAl (CO3)2(OH)2. The activation energy (E, kJ/mol) and pre‐index factor (A, min−1) of the three stages were 69.7, 73.8 and 84.5 and 1.36 × 107, 1.86 × 107 and 2.74 × 106, respectively. The reaction kinetic parameters were calculated by the thermal analysis method. A comprehensive model based on the Avrami–Erofeev reaction mechanism model was proposed for the regeneration process of K2CO3/Al2O3. The model data and test values agreed well, thereby establishing the model's accuracy. This paper provides fundamental data for further study on the capture of carbon dioxide from flue gas using potassium‐based sorbents.

Kinetic modeling of PM combustion with relative velocity at low-temperature and numerical simulation of continuous regenerating type PM removal device that uses a fluidized bed

The size of particulate matter (PM) generated by combustion has decreased with the improvement of combustion technology. While small PM has a significant negative impact on the human body, it is difficult for a conventional PM removal device to collect small PM. We developed a fluidized bed type PM removal device with a focusing adhesion force. This device collects small PM effectively and can be operated as a continuous regeneration device at low temperature. To further develop this device, it is important to investigate the PM combustion characteristics in this device. The kinetic model constructed in conventional thermogravimetry could not accurately represent the combustion rates of the solid fuel in the fluidized bed. Therefore, a new thermogravimetric apparatus was constructed in this study that generates the direct collision of air with carbon to reproduce the fluidized bed combustion. The influence of the relative velocity between PM and gas on the combustion rate was investigated. The effect of relative velocity was represented as the mass transfer coefficient of kinetic model. It is observed that the combustion rate shows Arrhenius behavior, and kinetic parameters were determined by fitting. The kinetic model was applied to the numerical simulations of the PM removal device. The numerical collection efficiency was in good agreement with the experimental data. PM adhesion and combustion characteristics were investigated in numerical simulations. It is observed that the adhesion rate is high at a low void fraction and that the combustion rate is high at a high relative velocity. The PM combustion amount is high for the high adhesion and combustion rates. The total combustion amount is determined to be 55% of the total amount of PM deposition after 180 min at each set of conditions.

The effect of heating rate, particle size and gas flow on the yield of charcoal during the pyrolysis of radiata pine wood

Charcoal derived from sustainable grown wood is a potential source of fuel and reductant for iron and steel making and a potential way to decrease the net CO2 emissions from the steelmaking industry. However a modern charcoal making process is likely to be required to supply the iron and steel industry with the required amount of charcoal to make significant difference to greenhouse gas emissions. The design of such a process requires fundamental knowledge on the effect of process variables on charcoal formation and yield during pyrolysis.The effect of biomass heating rate, purging gas flow and particle size on the yield of charcoal from pine wood was quantified in a series of pyrolysis experiments using a thermo-gravimetric apparatus. Temperature-time curves obtained during the heating of biomass showed the pyrolysis reactions became exothermic at about 350 °C. Increasing the flow of inert carrier gas through the biomass sample resulted in a decrease in charcoal yield and a faster rate of biomass decomposition. At zero gas flow the charcoal yield is independent of particle size. As gas flow through the sample is increased the yield of charcoal is increasingly dependent on increasing particle size.Increasing the wood heating rate from 0.11 to 10 °C/min, resulted in decreased charcoal yield. The period of fast biomass decomposition shifted to higher temperatures and the start of decomposition occurred at higher temperatures. These results indicate that low temperature reactions of charcoal formation are favoured by low heating rates and the initial charcoal acts as a catalyst for primary biomass decomposition. Lower heating rates are also associated with increased retention of pyrolysis vapours in the biomass which results is increased production of secondary charcoal and increased charcoal yield.

Alkali Treatment Effect: Mechanical, Thermal, Morphological, and Spectroscopy Studies on Abutilon Indicum Fiber-Reinforced Composites

ABSTRACT Applicability of natural fiber-reinforced composites in automobile, aerospace like sectors has been increasing as more number of research works is concentrating on natural fibers owing to their eco-friendly nature. Biodegradability of natural fibers is main advantage of them over artificial fibers. Natural fiber-reinforced composite possesses good thermal and mechanical properties besides other requirements. For this reason, investigation of one such natural fiber-reinforced composites has been the focus of the present study. In the present work, composites made up of abutilon indicum fiber reinforced with epoxy have been prepared. Mechanical, morphological, thermal, and spectroscopic studies on the test specimens prepared using the above composites were carried out to evaluate their respective strengths. Also, the effect of alkali treatment (NaOH) for the fibers was studied and evaluated. Scanning electron microscope results indicated that the composite made up of alkali-treated fibers possessed better mechanical properties. Using differential thermal analysis–thermogravimetric analysis apparatus thermal behavior of the composites and using Fourier transform infrared spectroscopic studies, the presence of function groups like C–O, C–H was determined. Thus, characterization of abutilon indicum fiber-reinforced epoxy composites has been carried and properties are evaluated for their applicability to automotive, aerospace similar industries.

Curcumin-Silk Fibroin Nanoparticles for Enhanced Anti-Candida albicans Activity In Vitro and In Vivo.

Curcumin (CM) has multiple pharmacological activities including anti-fungal activity, but its clinical application is limited due to low solubility in aqueous media, poor bioavailability and extensive first pass metabolism. We aimed to resolve the limitation and enhance antifungal activity of CM using nanotechnology. Using silk fibroin (SF) as a carrier, we fabricated curcumin-silk fibroin nanoparticles (CM-SF NPs) by solution enhanced dispersion of supercritical CO₂ (SEDS) technique. The characterization of CM-SF NPs was analyzed using scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), differential scanning calorimeter (DSC) and thermo gravimetric apparatus (TGA). Following characterization of the NPs, we evaluated the antifungal activity of CM-SF NPs against Candida albicans in vitro and in vivo. A SF-based drug delivery system (CM-SF NPs, 85 ± 15 nm) was established by SEDS. Compared to original CM, water solubility of CM-SF NPs was improved, and its antifungal activity was enhanced. The natural compound-loaded SF nanoparticles may be a promising therapeutic candidate for fungal infection.

Thermal degradation of waste plastics under non-sweeping atmosphere: Part 1: Effect of temperature, product optimization, and degradation mechanism

Continuous generation of plastic waste has prompted substantial research efforts in its utilization as a feedstock for energy generation. Pyrolysis has emerged as one of the best waste management technique for energy extraction from the plastic waste. The objective of this work is to investigate the effect of operating temperature on the liquid product yields in the pyrolysis process by non-isothermal heating. Non-catalytic thermal pyrolysis of waste polyethylene (PE) [high density polyethylene (HDPE)], waste polypropene (PP), waste polystyrene (PS), waste polyethylene terephthalate (PET) and mixed plastic waste (MPW) was carried out in a non-sweeping atmosphere in a semi-batch reactor at four different temperatures 450, 500, 550, and 600 °C. The minimum degradation temperature of the mixed and individual plastics was obtained using a thermogravimetric apparatus (TGA) at a heating rate of 20 °C/min. The TGA results show that all plastics degrade in a single step and the degradation temperatures of PS > PET > PP > HDPE, while mixed plastic degradation indicates two distinct degradation steps. Further, a waste polymer shows a lower degradation temperature than the virgin polymer. The degradation of HDPE is found to produce the maximum oil yield with minimum solid residue. The degradation of PET results in the highest amount of solid and benzoic acid as crystals and gas with no oil. Degradation of mixed plastic causes oil yield in the intermediate range of pyrolysis of individual plastic wastes. Overall, 500 °C is observed to be an optimum temperature for the recovery of low-density pyrolytic oil with the highest liquid yield. The degradation of PE and PP is found to be caused by random chain scission followed by inter and intramolecular hydrogen transfer. The degradation of PS occurs by side elimination or end chain scission followed by β-scission mechanism. The degradation of mix plastics results from random chain scission followed by β-scission mechanism. The effect of temperature on oil and gas recovery as well as recovery time was also assessed.

Effect of specimen geometry on kinetics of thermal decomposition of minerals in porous ceramic tiles

AbstractPorous ceramic tiles are used as covering for indoor vertical surfaces in buildings. Clay and limestone are the starting raw materials. The firing step consolidates the product's properties in the manufacturing process. In this step several reactions occur, among them are the dehydroxylation of the clay minerals and decomposition of the carbonates. This study determined the kinetics parameters associated with the decomposition of these 2 minerals. Two different methods of samples preparation were investigated. In the first method, 60 mg of a spray‐dried powder was submitted to analysis in traditional thermogravimetric equipment. In the second method, compacted specimens with dimensions of 80 × 20 × 2.5 mm³ and a mass of 7 g, compacted at 25 MPa, were submitted to analysis using customized thermogravimetric apparatus. The curves were obtained for 6 different heating rates between 2.5 and 20 K min−1. The activation energy, the pre‐exponential factor of the specific velocity equation, and the reaction mechanism were determined. Depending on the methods and compaction degree the activation energy varies from 177.0 to 224.7 kJ mol−1 and from 188.5 to 230.2 kJ mol−1 for kaolinite and calcium carbonate, respectively. For accurate measurement of the activation energy, the heat transfer needs to be considered for each particular experimental configuration.

Synthetic strategies for the enhancement of Mg(OH)2 thermochemical performances as heat storage material

This work deals with the study of influence of multi walled carbon nanotubes (CNTs) characteristics on thermochemical performance of hybrid materials based on Mg(OH)2 (M) as heat storage medium. Two different functionalized CNTs samples are investigated, separated curly tubes (SN) and bundles of straight nanotubes (BN). Hybrids were synthesized by reverse deposition precipitation method and their structure was characterized by X-ray analysis and scanning electron microscopy. The heat storage performance was studied through a thermogravimetric apparatus, simulating heat storage/release cycles. It is demonstrated that separated CNTs owning mainly carboxylic groups increase the interaction with precipitated magnesium hydroxide, improving the reacted fraction during dehydration/hydration cycle. In terms of dehydration/hydration conversion the samples’ rank is SN-M>Mg(OH)2>BN-M. SN-M exhibits higher heat storage/output capacity (~1250 kJ/kgMg(OH)2, ~350 MJ/m3).