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Showing papers on "Thermogravimetric analysis published in 2019"


Journal ArticleDOI
TL;DR: In this paper, the surface terminations of three transition metal carbide MXenes (Ti3C2Tx, Mo2CTx, and Nb2CTX) were investigated up to 1500 °C under a He atmosphere.
Abstract: Two-dimensional (2D) transition-metal carbides and nitrides (MXenes) have attracted significant attention due to their electronic, electrochemical, chemical, and optical properties. However, understanding of their thermal stability is still lacking. To date, MXenes are synthesized via top-down wet chemical etching, which intrinsically results in surface terminations. Here, we provide detailed insight into the surface terminations of three carbide MXenes (Ti3C2Tx, Mo2CTx, and Nb2CTx) by performing thermal gravimetric analysis with mass spectrometry analysis (TA–MS) up to 1500 °C under a He atmosphere. This specific technique enables probing surface terminations including hydroxyl (−OH), oxy (═O), and fluoride (−F) and intercalated species, such as salts and structural water. The MXene hydrophilicity depends on the type of etching (hydrofluoric acid concentration and/or mixed acid composition) and subsequent delamination conditions. We show that the amount of structural water in Ti3C2Tx increases with decre...

250 citations


Journal ArticleDOI
TL;DR: A new structural model for GO layers is proposed, which covers all spectroscopic data and explains the presence of the other oxygen functionalities besides carboxyl, phenolic –OH and epoxy groups.
Abstract: The purpose of this work is the structural analysis of graphene oxide (GO) and by means of a new structural model to answer the questions arising from the Lerf–Klinowski and the Lee structural models. Surface functional groups of GO layers and the oxidative debris (OD) stacked on them were investigated after OD was extracted. Analysis was performed successfully using Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-Vis), X-ray photoemission spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), Raman spectroscopy, solid-state nuclear magnetic resonance spectroscopy (SSNMR), standardized Boehm potentiometric titration analysis, elemental analysis, X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The analysis showed that graphene oxide layers, as well as oxidative debris contain different functional groups such as phenolic –OH, ketone, lactone, carboxyl, quinone and epoxy. Based on these results, a new structural model for GO layers is proposed, which covers all spectroscopic data and explains the presence of the other oxygen functionalities besides carboxyl, phenolic –OH and epoxy groups.

226 citations


Journal ArticleDOI
TL;DR: In this article, the use of easily obtainable and economic agricultural waste of corn silk (CS) for removal of Reactive Blue 19 (RB19) and Reactive Red 218 (RR218) dyes with the adsorption process was investigated.

201 citations


Journal ArticleDOI
TL;DR: It is believed that the hierarchical chrysanthemum-like CuCo2O4-CuO composites can be a good candidate for the high-performance Co-based spinel microwave absorbers.

186 citations


Journal ArticleDOI
TL;DR: The results show that Fe3O4/C-ACLS can remove 98%, 92% and 99% of Congo red, Titan yellow and Eriochrome blue black R, respectively and the adsorption process conforms to pseudo-second-order kinetics model, and the diffusion rate is controlled by many steps.

164 citations


Journal ArticleDOI
TL;DR: In this paper, LDH-biochar composites were synthesized in different molar ratios of Mg:Al (2:1, 3:1 and 4:1) using co-precipitation method.

162 citations


Journal ArticleDOI
TL;DR: The viability of chitosan-based nanocomposites films was found to be better than native chitOSan and PVA films and the adsorption property of prepared chito-based Nanocomposite films was tested for the removal of AB 1 dye.

154 citations


Journal ArticleDOI
TL;DR: The structural and morphological properties of the product, polypyrrole-based activated carbon (PPyAC4), support its applicability as an adsorbent and fit well to the pseudo-second-order kinetic model and the Freundlich isotherm equation, suggesting a chemisorption pathway.
Abstract: In this study, polypyrrole-based activated carbon was prepared by the carbonization of polypyrrole at 650 °C for 2 h in the presence of four-times the mass of KOH as a chemical activator. The structural and morphological properties of the product (polypyrrole-based activated carbon (PPyAC4)), analyzed by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and thermogravimetric analysis, support its applicability as an adsorbent. The adsorption characteristics of PPyAC4 were examined through the adsorption of lead ions from aqueous solutions. The influence of various factors, including initial ion concentration, pH, contact time, and adsorbent dose, on the adsorption of Pb2+ was investigated to identify the optimum adsorption conditions. The experimental data fit well to the pseudo-second-order kinetic model (R2 = 0.9997) and the Freundlich isotherm equation (R2 = 0.9950), suggesting a chemisorption pathway. The adsorption capacity was found to increase with increases in time and initial concentration, while it decreased with an increase in adsorbent dose. Additionally, the highest adsorption was attained at pH 5.5. The calculated maximum capacity, qm, determined from the Langmuir model was 50 mg/g.

149 citations


Journal ArticleDOI
TL;DR: In this paper, the surface of cellulose fibers is successfully modified using the air plasma treatment with the aim of improving the matrix/fiber adhesion, and the modified fibers are studied using X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR).
Abstract: This work deals with provision and characterization of the biopolymer-based composites achieved by incorporation of cellulose fibers as the reinforcement within the glycerol plasticized matrix formed by thermoplastic cornstarch biopolymer. The function of starch-based polymers is limited due to poor mechanical properties. However, it is improved with forming a biocomposite of thermoplastic starch (TPS) as matrix and the cellulose fibers (CF) as reinforcement. The surface of cellulose fibers is successfully modified using the air plasma treatment with the aim of improving the matrix/fiber adhesion. The modified fibers are studied using X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The TPS/CF composites are prepared using high friction and hot compression procedure. Tensile test results and SEM images of the fracture surfaces show significant improvement of adhesion between treated cellulose fibers and TPS matrix. Thermogravimetric analysis shows a considerable decomposition at approximately 250–350 °C. XRD proved the significant increase in crystallinity percentage of composites compared to TPS.

147 citations


Journal ArticleDOI
TL;DR: Findings support the potential utility of MIL‐100(Fe) as nanoadsorbent in phosphate removal for water management as well as the development and performance of highly effective phosphate‐adsorbent.

145 citations


Journal ArticleDOI
TL;DR: In this article, a series of chitosan and polyvinyl alcohol (Cs/PVA) blend films doped with various concentrations of Zinc oxide nanoparticles (ZnO NPs) were prepared by solution casting method.

Journal ArticleDOI
TL;DR: The developed adsorbent could be used for efficient adsorptive removal of trace drugs and personal care products from water bodies after four consecutive cycles, with removal efficiency exceeding 70%.

Journal ArticleDOI
Yuanbin Zhang1, Lifeng Yang1, Lingyao Wang1, Simon Duttwyler1, Huabin Xing1 
TL;DR: The good cyclability and high water/thermal stability render it suitable for real industrial applications, and the practical separation performance of C3 H8 /CH4 and C2 H6 / CH4 was confirmed by dynamic breakthrough experiments.
Abstract: A novel 3D metal-organic framework BSF-1 based on the closo-dodecaborate cluster [B12 H12 ]2- was readily prepared at room temperature by supramolecular assembly of CuB12 H12 and 1,2-bis(4-pyridyl)acetylene. The permanent microporous structure was studied by X-ray crystallography, powder X-ray diffraction, IR spectroscopy, thermogravimetric analysis, and gas sorption. The experimental and theoretical study of the gas sorption behavior of BSF-1 for N2 , C2 H2 , C2 H4 , CO2 , C3 H8 , C2 H6 , and CH4 indicated excellent separation selectivities for C3 H8 /CH4 , C2 H6 /CH4 , and C2 H2 /CH4 as well as moderately high separation selectivities for C2 H2 /C2 H4 , C2 H2 /CO2 , and CO2 /CH4 . Moreover, the practical separation performance of C3 H8 /CH4 and C2 H6 /CH4 was confirmed by dynamic breakthrough experiments. The good cyclability and high water/thermal stability render it suitable for real industrial applications.

Journal ArticleDOI
TL;DR: Biodegradable starch-pectin‑titanium oxide nanoparticles (TiO2 - NPs) blend edible films developed by casting filmogenic solution of sweet potato starch and lemon waste pectin incorporated with TiO2 nanoparticles revealed that with UV prevention capacity, the developed films can be used as food grade UV screening biodesgradable packaging material.

Journal ArticleDOI
Chenglong Jiang1, Xiaohong Wang1, Ganghu Wang1, Chen Hao1, Xin Li1, Tihai Li1 
TL;DR: In this paper, the effects of temperature, acidity and alkalinity, dosage of adsorbent, adsorption time and concentration of heavy metal ions on the performance of Glucan/chitosan (GL/CS) hydrogels as adsorbents for heavy metal ion in wastewater treatment were discussed.
Abstract: Glucan/chitosan (GL/CS) hydrogels as adsorbents for heavy metal ions in wastewater treatment were synthesized by ultrasound-assisted free radical polymerization. The samples were characterized by Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). In the study of adsorption process, the effects of temperature, acidity and alkalinity, dosage of adsorbent, adsorption time and concentration of heavy metal ions on adsorption behavior of GL/CS adsorbent in simulated wastewater were discussed. On the basis of the above research, the adsorption thermodynamics, adsorption kinetics and adsorption mechanism were also studied. When the temperature was 20 °C, the pH value was 7.0 and the amount of adsorbent was 0.01 g, the results showed that the adsorption capacities of GL/CS hydrogels for Cu2+, Co2+, Ni2+, Pb2+ and Cd2+ were 342 mg g−1, 232 mg g−1, 184 mg g−1, 395 mg g−1, 269 mg g−1, respectively. The fitting results of the isothermal models, the kinetic models and thermodynamics of the experimental data of the ion adsorption process show that the adsorption of heavy metal ions by GL/CS is a spontaneous process of single-layer chemisorption.

Journal ArticleDOI
TL;DR: The results indicated that the layer-by-layer assembly and ferulic acid crosslinking combination increased the tensile strength and light-blocking ability of the films and had lower water vapor transmission rate, swelling degree, and water solubility, as well as higher hydrophobicity.

Journal ArticleDOI
TL;DR: It is now shown that automated TED-GC-MS represents a new flexible multi-functional method for comprehensive polymer analyses and good linearity for the most important precursors for microplastic, even complex matrix materials (suspended particulate matter) can be successfully analyzed.

Journal ArticleDOI
TL;DR: Modified cellulose hydrogels were prepared by blending and cross-linking with acrylamide and acrylic acid and the adsorption mechanisms such as physical, chemical, and electrostatic interactions are discussed.

Journal ArticleDOI
TL;DR: In this paper, a shape-stabilized phase change material (PCM) prepared by impregnating eutectic salt hydrate (Na2SO4·10H2O-Na2CO3·10 H2O with 1:1 in mass ratio) into expanded vermiculite (EV) is carried out.

Journal ArticleDOI
TL;DR: In this paper, the influence of ultrafine fly ash (FA) on the mechanical properties, elevated temperature resistance and water stability of basalt fiber reinforced magnesium phosphate cement, and synergy mechanism was examined with the help of X-ray diffraction (XRD), thermogravimetric analysis (TGA), mercury intrusion porosimeter (MIP) and scanning electron microscopy energy dispersive spectroscopy (SEM/SEM-EDS) analysis techniques.
Abstract: This study investigated the influence of ultrafine fly ash (FA) on the mechanical properties, elevated temperature resistance and water stability of basalt fiber reinforced magnesium phosphate cement, and synergy mechanism was examined with the help of X-ray diffraction (XRD), thermogravimetric analysis (TGA), mercury intrusion porosimeter (MIP) and scanning electron microscopy energy dispersive spectroscopy (SEM/SEM-EDS) analysis techniques. Experimental results showed that incorporation of FA improved the mechanical properties, temperature resistance and water stability of MPC composites. TGA results exhibited that the mass loss of MPC composites was gradually reduced by increasing the percentage of FA. MIP analysis showed that cumulative pore volume, volume percentage of large pores and mean pore diameter of were decreased with the addition of FA. XRD and SEM-EDS analysis of MPC composites revealed the formation of secondary reaction products, that could be possibly responsible for the superior properties of FA/MPC composites. Importantly, the results of all characterization techniques corroborated with the mechanical results of MPC composites.

Journal ArticleDOI
TL;DR: In this paper, a polyethylene oxide (PEO) embedded with carbon nanotubes and gold nanoparticles (MWCNTs/Au NPs) was prepared through the casting method and the polymer-nanoparticle interactions were examined by Fourier transform infrared (FT-IR) measurement.
Abstract: Polymer nanocomposite samples of polyethylene oxide (PEO) embedded with multi-walled carbon nanotubes and gold nanoparticles (MWCNTs/Au NPs) were prepared through the casting method The polymer–nanoparticle interactions had been examined by Fourier transform infrared (FT-IR) measurement. X-ray diffraction (XRD) analysis depicted that these samples were semi-crystalline and the crystalline phases of PEO were reduced due to the incorporation of MWCNTS/Au NPs. The TEM micrographs indicated that the diameter range of MWCNTs is 10–25 nm and the shape of Au NPs was spherical with size range 2–25 nm. The redshift of absorption edge in the spectra of ultraviolet/visible (UV–Vis.) spectroscopy for the nanocomposite samples indicated a good reactivity between the polymer matrix and the nanofillers which in turn the decrement of optical energy gap value was expected, which was calculated from Tauc's relation. The thermal stability of nanocomposite samples was improved as indicated by the thermogravimetric analysis (TGA) technique. The electrical and dielectric spectra of these samples had been measured using broadband dielectric spectroscopy. The electrical and dielectric measurements realize the favorable uses of these nanocomposite samples in the production of electroactive materials and further their use as the electrical insulating polymeric nanodielectrics in the production of organoelectronic devices. The Mechanical properties of the prepared samples were calculated by the tensile universal testing machine.

Journal ArticleDOI
TL;DR: Characterization results demonstrated that the high capture capability of MOF-74 (Ni) materials can be attributed to the synergistic effect of abundant narrow micropore channels and rich five-coordinated Ni2+ open metal sites which are beneficial for the trapping of CO2 molecules.
Abstract: In the present work, a series of MOF-74 (Ni) materials with narrow micropore channels and abundant unsaturated metal sites was respectively prepared via hydrothermal (HT), condensation reflux (CE), and microwave-assisted (MW) methods. The physicochemical properties of synthesized materials were characterized by powder X-ray diffraction, N2-sorption, field-emission scanning electron microscopy, Fourier-transform infrared (FTIR), thermogravimetric (TG)/TG-FTIR, X-ray photoelectron spectroscopy, UV-vis-near infrared, NH3/CO2-temperature programmed desorption, and in situ diffuse reflectance infrared Fourier transform spectroscopy. Their CO2/N2 adsorption performances were evaluated by isotherm adsorption and dynamic adsorption experiments. We found that the MW is a rapid and facile protocol for the synthesis of MOF-74 (Ni) materials with highly efficient CO2 capture capacity. The well-shaped MW-140 adsorbent with superior CO2 adsorption capacity of 5.22 mmol/g at 25 °C can be obtained within 60 min by the MW process, almost 6 times higher than that of the commercial activated carbon (0.89 mmol/g). Results of dynamic adsorption experiments showed that the MW-140 material possesses the highest CO2 adsorption capacity of 3.37 mmol/g under humid conditions (RH = 90%). Importantly, MW-140 has excellent adsorption stability and recyclability, superior CO2 capture selectivity (CO2/N2 = 31), and appropriate isosteric heat in CO2 adsorption (21-38 kJ/mol), making it a promising and potential material for industrial CO2 capture. Characterization results demonstrated that the high capture capability of MOF-74 (Ni) materials can be attributed to the synergistic effect of abundant narrow micropore channels and rich five-coordinated Ni2+ open metal sites which are beneficial for the trapping of CO2 molecules.


Journal ArticleDOI
TL;DR: A novel magnetic bio-adsorbent has been prepared by the loading of Fe3O4 NPs and immobilization of 1,4-butane sultone on the surface of activated carbon that shows advantages such as green synthesis, low cast, recyclability, and easy separation.

Journal ArticleDOI
01 Jan 2019-Vacuum
TL;DR: In this paper, different ratios between polyethylene oxide (PEO) and carboxymethyl cellulose (CMC) blends were prepared through the solution casting technique, and the X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) were used to investigate the blends.

Journal ArticleDOI
TL;DR: In this article, the authors demonstrated the preparation and environmental adsorption applications of 2D material MXenes through extracting Al layer from Ti3AlC2 in a simpler and safer way.

Journal ArticleDOI
TL;DR: In this article, the effects of carbon fiber hybridization on the thermal properties of woven kenaf-reinforced epoxy composites were studied by using a thermogravimetric analyser and differential scanning calorimeter (DSC).
Abstract: The effects of carbon fibre hybridisation on the thermal properties of woven kenaf-reinforced epoxy composites were studied. Woven kenaf hybrid composites of different weave designs of plain and satin and fabric counts of and were manually prepared by a vacuum infusion technique. A composite made from 100% carbon fibre was served for a comparison purpose. Thermal properties of pure carbon fibre and hybrid composites were determined by using a thermogravimetric analyser (TGA) and differential scanning calorimeter (DSC). It was found that a hybrid composite with higher kenaf fibre content (fabric count ) showed better thermal stability while the highest thermal stability was found in the pure carbon fibre composite. The TG and DTG results showed that the amount of residue decreased in the plain-designed hybrid composite compared to the satin-designed hybrid composite. The DSC data revealed that the presence of woven kenaf increased the decomposition temperature.

Journal ArticleDOI
TL;DR: In this paper, modified defective UiO-66 was successfully synthesized using another MOF (MOF-5) as structural modifier, which was found that the modified material (M-U-0.01) formed a certain number of defects when the MOF5/Zr4+ ratio was 0.01 which was conducive to toluene adsorption.
Abstract: In this work, modified defective UiO-66 was successfully synthesized using another MOF (MOF-5) as structural modifier. Some analytical techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), N2 adsorption-desorption isotherms and thermogravimetric (TG) had been used to characterize pristine and modified UiO-66. Moreover, static adsorption tests, dynamic adsorption tests and toluene temperature programmed desorption (TPD) measurement had been used to explore toluene adsorption/desorption capacity and kinetics. It was found that the modified material (M-U-0.01) formed a certain number of defects when the MOF-5/Zr4+ ratio was 0.01, which was conducive to toluene adsorption. The M-U-0.01 (257 mg g−1) demonstrated 1.7 times toluene sorption property of the pristine UiO-66 (151 mg g−1). The interactions between toluene and pristine and modified MOFs were analyzed through the isosteric adsorption heat (ΔHads) and the Henry’s law constant (KH), indicating that toluene molecules and M-U-0.01 had a strong interaction. The effect of relative humidity and temperature on the toluene sorption property was further studied. Modified defective UiO-66 displayed good thermal stability and reproducibility.

Journal ArticleDOI
Wanli Zhang1, Chang Shu1, Qiuyi Chen1, Jiankang Cao1, Weibo Jiang1 
TL;DR: The multi-layer film system is a promising controllable release system for loading essential oils and demonstrated that the layer-by-layer method improved the release and retention of CEO in the multiphased system.

Journal ArticleDOI
26 Jun 2019-Polymers
TL;DR: Kevlar can be efficiently (50%) replaced with CS at an optimal GNP loading for structural applications due to effective crosslinking, which improves the stress transfer rate.
Abstract: The aim of the present research work is to enhance the thermal and dynamic mechanical properties of Kevlar/Cocos nucifera sheath (CS)/epoxy composites with graphene nano platelets (GNP). Laminates were fabricated through the hand lay-up method followed by hot pressing. GNP at different wt.% (0.25, 0.5, and 0.75) were incorporated with epoxy resin through ultra-sonication. Kevlar/CS composites with different weight ratios (100/0, 75/25, 50/50, 25/75, 0/100) were fabricated while maintaining a fiber/matrix weight ratio at 45/55. Thermal degradation and viscoelastic properties were evaluated using thermogravimetric analysys (TGA), differential scanning calorimetric (DSC) analysis, and a dynamic mechanical analyser (DMA). The obtained results revealed that Kevlar/CS (25/75) hybrid composites at 0.75 wt.% of GNP exhibited similar thermal stability compared to Kevlar/epoxy (100/0) composites at 0 wt.% of GNP. It has been corroborated with DSC observation that GNP act as a thermal barrier. However, DMA results showed that the Kevlar/CS (50/50) hybrid composites at 0.75 wt.% of GNP exhibited almost equal viscoelastic properties compared to Kevlar/epoxy (100/0) composites at 0 wt.% GNP due to effective crosslinking, which improves the stress transfer rate. Hence, this research proved that Kevlar can be efficiently (50%) replaced with CS at an optimal GNP loading for structural applications.