TGA Weight Research Articles

Process optimization and characteristics of enzymatically cross-linked and ultrafiltrated whey

Whey, a byproduct of cheese production, is valued for its high-quality proteins. Ultrafiltration concentrates these proteins but faces challenges such as membrane fouling. This study investigates the use of transglutaminase to improve ultrafiltration efficiency by reducing fouling and optimizing protein recovery. Whey was divided into samples of whey in natura (WIN) and whey partially demineralized (WPD). Both were treated with different concentrations of transglutaminase (0, 0.5, 1.5, and 2.5% relative to protein mass) and ultrafiltered using polyethersulfone membranes at 4 bar. Effectiveness was evaluated by permeate flux and protein concentration, as well as physicochemical and structural characterizations such as FTIR, TGA, and molecular weight analysis. Transglutaminase reduced membrane fouling, increasing permeate flux. The 2.5% enzyme concentration was most efficient for WIN, while 1.5% was ideal for WPD. Enzymatic treatment increased protein concentration and thermal stability of the concentrates. FTIR analysis indicated the formation of cross-links between proteins. Molecular weight analysis revealed larger and more stable protein aggregates, improving ultrafiltration performance. This study suggests that transglutaminase is promising for optimizing whey ultrafiltration, improving protein recovery and process efficiency, with potential large-scale application in the food industry.

Preparation of Quaternary Ammonium Separation Material based on Coupling Agent Chloromethyl Trimethoxysilane (KH-150) and Its Adsorption and Separation Properties in Studies of Th(IV).

In this research, the authors studied the synthesis of a silicon-based quaternary ammonium material based on the coupling agent chloromethyl trimethoxysilane (KH-150) as well as its adsorption and separation properties for Th(IV). Using FTIR and NMR methods, the silicon-based materials before and after grafting were characterized to determine the spatial structure of functional groups in the silicon-based quaternary ammonium material SG-CTSQ. Based on this, the functional group grafting amount (0.537 mmol·g-1) and quaternization rate (83.6%) of the material were accurately calculated using TGA weight loss and XPS. In the adsorption experiment, the four materials with different grafting amounts showed different degrees of variation in their adsorption of Th(IV) with changes in HNO3 concentration and NO3- concentration but all exhibited a tendency toward anion exchange. The thermodynamic and kinetic experimental results demonstrated that materials with low grafting amounts (SG-CTSQ1 and SG-CTSQ2) tended to physical adsorption of Th(IV), while the other two tended toward chemical adsorption. The adsorption mechanism experiment further proved that the functional groups achieve the adsorption of Th(IV) through an anion-exchange reaction. Chromatographic column separation experiments showed that SG-CTSQ has a good performance in U-Th separation, with a decontamination factor for uranium in Th(IV) of up to 385.1, and a uranium removal rate that can reach 99.75%.

Detection and quantification of low levels of carbonate mineral species using thermogravimetric-mass spectrometry to validate CO2 drawdown via enhanced rock weathering

Enhanced rock weathering (ERW) is a promising technology being actively investigated to ameliorate anthropogenic climate change. ERW accelerates atmospheric carbon dioxide (CO2) drawdown in agricultural soils following the addition of crushed, silicate rocks. The application of basalt, an abundant silicate rock, has widely been proposed for ERW. In order to measure and model the efficacy of ERW, it is critical to fully characterise the mineralogical composition of the basaltic materials being deployed in laboratory to catchment scale experiments.As previously demonstrated on analogous basaltic rock and soil materials on Mars, thermal analytical methods such as coupled thermogravimetric analysis-mass spectrometry (TGA-MS), provide a potentially rapid, effective technique to identify and also quantify the carbonate mineral species present in ERW basalts and their weathering products.Our study of six different basaltic materials used in ERW experiments, from widely different geological and geographical settings, suggests that TGA weight losses can provide useful information on the low-levels of carbonate minerals present. Furthermore, carbonate mineral identification and quantification derived from the accompanying MS-detected CO2 evolution and corroborated by SEM-EDS mapping, is capable of detecting even lower concentrations with detection limits below 100 ppm for calcite. TGA-MS therefore offers significant advantages over the traditionally-applied inorganic carbon analyses.Carbonate mineral weight losses encountered during TGA and their accompanying CO2-evolutions have previously been ascribed to relatively small, defined temperature ranges. However, crucially, this study has revealed the concentration-dependent, large-scale variation in the mass spectrometric peak CO2-evolution for a range of carbonate minerals. A knowledge of such parameters is imperative for the accurate interpretation of basalt TGA-MS output, the characterisation of these materials and assessment of ERW technologies.

Structural investigation and optical properties of Fe, Al, Si, and Cu–ZnTiO3 nanocrystals

Synthesis, morphology control, and diffuse reflectance of Fe/Al/Si/Cu–ZnTiO3 prepared using the sol-gel method and calcined at 750 °C have been inspected. The Fe, Al, Si, and Cu can interchange the Ti ions and form sols in the ZnTiO3 matrix. The microstructural and optical properties of the ZnTiO3 were affected by the dopant. X-ray diffraction patterns and FullProf software exhibited the forming of the ZnTiO3 rhombohedral phase. The introduction of Fe, Al, Si, and Cu in the rhombohedral ZnTiO3 structure results in trigonal and triclinic phases for Al and Si and monoclinic phases for Fe and Cu. The various dopants convince the topical ZnTiO3 surface morphology modification observed by SEM. The total TGA weight loss of about<3% through the heating from ambient to 700 °C for all tested samples reflects its high stability.The prepared nanocrystalline powders undergo both direct and indirect energy band transitions with a direct type, which is more probable where it needs lower energy. The bandgap value of the nanocrystalline powder is slightly increased by different doping unless Fe, which leads to its decrease. The doped samples show a significant shift in the bandgap due to the introduction of electronic level, which forms the lowest unoccupied molecular orbital within the bandgap states of ZnTiO3.

Styrene intermolecular associating incorporated-polyacrylamide flooding of crude oil in carbonate coated micromodel system at high temperature, high salinity condition: Rheology, wettability alteration, recovery mechanisms

Polymer flooding is one of the most well-known research interests in the enhanced oil recovery (EOR) due to the excess oil production and limited petroleum reserve. Commercial polymers such as polyacrylamide (PAM) and its hydrolyzed form (HPAM) can be easily degraded at high temperature, high salinity, and high shear rate in attempt to the EOR purposes for the harsh reservoir conditions. In this work, a hydrophobically modified copolymer consisting of acrylamide and styrene (HSPAM) was produced via inverse emulsion polymerization as a wettability modifier and viscosifying agent, applicable under harsh reservoir conditions to direct insights into the synergic oil recovery pore scale mechanisms and overcoming the aforementioned challenges through the EOR process. In the first part of this study, a set of analytical techniques including FTIR, NMR, TGA, and molecular weight measurement was carried out, confirming successfully incorporation of styrene monomer in water-soluble skeleton and higher thermal resistivity of HSPAM compared with HPAM. By analyzing the rheological behavior of HSPAM under harsh reservoir conditions, it was found that the viscosity of HSPAM aqueous solution was increasingly influenced by the total dissolved solids, even up to 40,572 mg/L. In the second part, stability tests, contact angle (CA), interfacial tension (IFT), and carbonate coated glass micromodel flooding experiments were conducted by deionized water (DIW), seawater (SW) and formation brine (FB) in the absence and presence of HSPAM and HPAM. HSPAM illustrated a great stability in seawater and formation brine in comparison with HPAM after 120 days at 80 °C. The presence of HSPAM in seawater resulted in a more water-wet state up to 42° compared to HPAM by contact angle of 31° after 72 h. Findings provided synergic oil recovery mechanisms approved by emulsification and coalition phenomena to show a better wettability alteration and IFT reduction for HSPAM in spite of HPAM alongside drastically improving the brine-based flooding performance, yielding an ultimate recovery of about 82% original oil in place (OOIP).

Ni/La2O3 catalysts for dry reforming of methane: Effect of La2O3 synthesis conditions on the structural properties and catalytic performances

10 wt%Ni/La2O3 catalysts for dry reforming of methane (DRM) were synthesized by wetness impregnation of lanthana supports prepared using sol-gel citric method with and without NH3 addition (Ni–La CA-NH3 and Ni–La CA, respectively). The support preparation conditions affect the nature, phase composition, and distribution of Ni phases (LaNiO3, NiO and La3Ni2O6). The gradient temperature DRM tests (400–800 °C) reveal higher catalytic activity of Ni–La CA (at 650 °C, X(CO2) = 65.7%, X(CH4) = 54.6%, H2/CO = 0.71). The Ni–La CA-NH3 shows higher stability (at 650 °C and 24 h, X(CO2): 73.7% => 76.4%, X(CH4): 64.7% => 64.6%, H2/CO: 0.77 => 0.72). For both catalysts, La2O2CO3 phase is formed after long run tests at 650 °C 24 h, with the greater TGA weight loss and stronger deactivation being observed for Ni–La CA. The H2-reduced Ni La CA-NH3 features ultrasmall (1–2 nm) Ni NPs strongly interacting with the support. Catalyst nature affects the amount of carbon coke formed.

Use of eggshell powder as a potential hydrolytic retardant for citric acid-filled thermoplastic starch

In this study, the effects of eggshell powder and citric acid on the properties of thermoplastic starch (TPS) were investigated. All components were melt-blended using an internal mixer. Citric acid led to the formation of crosslinking structures (as shown in the FTIR spectra at 1730 cm−1) and caused rapid sample biodegradation with accelerated hydrolysis. Conversely, addition of eggshell powder retarded the biodegradation. After storing the samples for 30 days, CaTPS (Cassava root TPS) without eggshell powder showed erosion over almost the entire surface, while the surface of CaTPS containing 20 phr of eggshell powder (CaTPSES20) remained unchanged. The residual TGA weight at 400 °C and the change in carbonate FTIR intensity peak of CaTPSES20 after the storage period provided both quantitative and qualitative evidence that eggshell powder can be considered a potential hydrolytic retardant for citric-acid-filled TPS.

CHARACTERIZATION OF CERTAIN PHYSICAL PROPERTIES ON MODIFIED KAOLINITE-COUPLED CATALYSTS PREPARED WITH AG AND ZN IONS

This study used kaolinite clay as a carrier and exchanged Ag+ and Zn2+ onto the kaolinite via ion exchange. The coupled kaolinite-Ag/Zn catalysts at the nanolevel were formed after surface modification. Various physicochemical experiments, such as Fourier-transform infrared spectroscopy (FT-IR) analysis, x-ray diffraction (XRD) analysis, transmission electron microscopy (TEM) analysis, thermal analysis, and potentiometric titration analysis were conducted to further discuss the physicochemical properties of the kaolinite-Ag/Zn catalysts. &#x0D; First, a function group analysis on the kaolinite clay conducted using a Fourier-transform infrared spectrometer showed many significant and complex wave crests in the following wavenumber sections of the fingerprint area: 415~600 cm-1 and 750~1170 cm-1; these represent strong bonds between impure silicates (Si-O) and silicates (O-Si-O) within the silicate mineral. The mineral structures of the kaolinite-Ag/Zn catalysts remained intact after being sintered at 350oC. In terms of the x-ray diffraction analysis, following high-temperature sintering a dehydration reaction occurred in the kaolinite-Ag/Zn catalysts. The spacing of layers was thereby narrowed to 0.7170 nm. Moreover, a TEM observation of the kaolinite-Ag/Zn catalysts after high-temperature sintering showed that the sizes of Ag+ and Zn2+ on the kaolinite-Ag/Zn catalysts were between 25 and 60 nm, respectively. This proves that with ion exchange, the kaolinite-Ag/Zn catalysts are at the nanolevel. Regarding thermal analysis, the kaolinite-Ag/Zn catalysts had endothermic peaks at 464oC, 527oC and 888oC, respectively and exothermic peaks at 585oC and 921oC, respectively. As for TGA weight loss, two pyrolysis temperatures were found: The first pyrolysis occurred at 464oC, where the weight loss was caused by oxidative pyrolysis. The second pyrolysis occurred at 775oC, where the TGA weight loss resulted from decomposition of the remaining organic (carbon-containing) compounds. Lastly, regarding potentiometric titration, there were two end points of the titration for the kaolinite-Ag/Zn catalysts, indicating that there are two different acidic function groups. The titration curves of these said end points were obviously affected by two ions, and these two end points of the titration were quite obvious. The intensities of the two acidic function groups were similar; consequently, there is an obvious two-stage dissociation in the titration curves.

Study on combustion and emission characteristics of chars from low-temperature and fast pyrolysis of coals with TG-MS

To achieve the clean and efficient utilization of low-rank coal, the combustion and pollutant emission characteristics of chars from low-temperature and fast pyrolysis in a horizontal tube furnace were investigated in a TG-MS analyzer. According to the results, the combustion characteristic of chars was poorer than its parent coals. The temperature range of gaseous product release had a good agreement with that of TGA weight loss. Gaseous products of samples with high content of volatile were released earlier. The NO and NO&lt;sub&gt;2&lt;/sub&gt; emissions of chars were lower than their parent coals. Coals of high rank (anthracite and sub-bituminous) released more NO and NO&lt;sub&gt;2&lt;/sub&gt; than low rank coals of lignite, so were chars from coals of different ranks. SO&lt;sub&gt;2&lt;/sub&gt; emissions of char samples were lower than parent coals and did not show obvious relationship with coal ranks.

Probing the dynamic and rehealing behavior of crosslinked polyester networks containing thermoreversible thiol-Michael bonds

A thermoreversible thiol-Michael bond was incorporated into a series of covalently crosslinked polyester networks using base-catalyzed Michael addition polymerization. Variations in acrylate:acetoacetate ratio (crosslink density), thiol-Michael bond content and cure temperature were employed in order to gauge dynamic and rehealing properties. All of the networks investigated in this study were found to display rehealing behavior after being cut at 100 °C within 48 h. Increasing the curing temperature to 120 °C led to a decrease in time to reheal (≤8 h), however the network which employed the highest thiol-Michael bond content, coupled with the lower acrylate:acetoacetate monomer ratio, did not recuperate the original crosslink density upon cooling as evidenced by strain recovery values in excess of 100% and a steady decrease in DSC Tg and TGA weight % as a functional of exposure time.

Comparative Study of Different Immobilization of Strontium inLiSr2(PO4)3 Crystal through Hydrothermal Process

The main objective of the present study was to synthesis the different immobilization of Sr+2 in LiSr2(PO4)3crystals using soft hydrothermal method at moderate pressure and temperature conditions.The powder X-ray diffraction confirms that, the synthesized LiSr2(PO4)3material has very good phase purity and crystalline with rhombohedralstructure.The energy-disperse X-ray (EDX) spectroscopic analysis shows their elemental composition correlating well with that of the strontium.Observation through a Scanning Electron Microscope (SEM) shows that microstructures of good quality and exhibited smooth surface, sub transparent and sub vitreous lustre. The FTIR studies was used to determine whether the bond structures were affected from the doping or not and revealed that the presence of O-H molecules and minute structural variations of synthesized materials.The TGA graph, temperature vs. weight % loss decreases with increasing the temperature showsLithium strontium phosphateas thermally stable so it is used as some optoelectronic device applications.The electrical conductivity of LiSr2(PO4)3was investigated as a function of the nature of the transition-metal cation. Impedancemeasurementshow that the materials have relatively good ionic conductance.

Enhancing antifouling performance of poly(l‐lactide) membranes by TiO2 nanoparticles

ABSTRACTPoly(l‐lactide) (PLLA)/TiO2 composite membranes were fabricated by immersion precipitation method. The resulting membranes were characterized using various methods including XRD, ATR‐FTIR, TGA, DSC, SEM, goniometer, and molecular weight cut‐off. The antifouling performance of the membrane was investigated through the filtration experiments of the oil/water emulsion. XRD, SEM, and ATR‐FTIR results indicated that TiO2 was successfully introduced into the membrane, while DSC and TGA indicated the enhancement of thermal stability of membrane. The improvement of membrane hydrophilicity was confirmed by goniometer. In addition, the pore size and porosity on the membrane surface varied obviously with increasing the TiO2 loading. It was concluded that PLLA/TiO2 composite membranes had better antifouling and recycling performance compared with the pure PLLA membrane. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43542.

Thermal degradation study of PVA derivative with pendant phenylthionecarbamate groups by DSC/TGA and GC/MS

The thermal study of poly(vinyl phenylthionecarbamate) was carried out through DSC and TGA analysis. DSC curve affords five decomposition steps whose temperature ranges were consistent with the TGA weight loss graphic. Tg transition takes place at 219 °C. The largest PVA-PT mass loss occurs at 120–340 °C, within two overlapped process with an average ΔH = 170.4 J/g. These processes were assigned to the vicinal hydroxyl groups' water elimination, followed by the polymer defunctionalization. The PVA derivative thermal decomposition mechanism was proposed based on GC/MS results.

Synergistic effects of pretreatment and blending on fungi mediated biodegradation of polypropylenes

Environmental issues raise concern on restrict the use of nondegradable polymers and encourage the development of degradable once. This study is carried out was to understand the rate of biodegradation of untreated and pretreated (100°C or UV for 10 days) polypropylene (PP), pro-oxidant blended (MI-PP) and starch blended polypropylenes (ST-PP) with two different fungal strains, Phanerochaete chrysosporium NCIM 1170 (F1) and Engyodontium album MTP091 (F2). About 18.8% and 9.42% gravimetric weight loss and 79% and 57% TGA weight loss (at 400°C) were observed with UV pretreated MI-PP in 1 year with F2 and F1 strains respectively. The amount of lacasse produced by the organism and biomass attached on the polymer surface are correlated with TGA weight loss (0.6-0.93). The formation of extractable oxygenated compounds and unoxidized low-molecular weight hydrocarbons are high in pretreated and blended samples. These results indicate blending and pretreatment strategy leads to an optimal waste-disposal strategy.

Enhancement in the photocatalytic degradation of low density polyethylene–TiO2 nanocomposite films under solar irradiation

An enhancement in the photocatalytic degradation of low-density polyethylene (LDPE) under solar radiation was accomplished by incorporating titania nanoparticles (TiO2) of size 15 nm in the polythene matrix. The LDPE–TiO2 nanocomposite film was prepared through a simple solution casting technique with 0.1 wt% TiO2 nanoparticles. The photocatalytic degradation of the LDPE–TiO2 nanocomposite was investigated using FE-SEM, FT-IR, XPS, XRD, TGA and photoinduced weight loss analysis. To ensure the wide applicability of the method in environmental remediation, the photocatalytic degradation was carried out under solar radiation. We observed that, when exposed to solar radiation, the composite films showed a significant weight loss of 68% within a period of 200 h, which is a remarkable improvement compared to the previous reports. FT-IR and XPS analysis confirmed the presence of carbonyl groups with a carbonyl index of 19, which led to the degradation of LDPE. FE-SEM analysis revealed the mechanism of degradation of the LDPE matrix on the surface of TiO2 through the formation of pores at the interface. Thus we put forward the development of eco-friendly photodegradable plastic as a solution for the growing concerns of plastic pollution.

Solution Phase Photolysis of 1,2-Dithiane Alone and with Single-Walled Carbon Nanotubes

Photolysis of 1,2-dithiane (1) in acetonitrile with single walled carbon nanotubes (SWCNTs) was earlier reported to form thiol-functionalized SWCNTs via the butane-1,4-dithiyl diradical (2). The present study shows that 2 instead undergoes a facile rearrangement to thiophane-2-thiol (6). This photoreaction is clean, rapid, and irreversible under 313 nm irradiation. The secondary photolysis of 6 with SWCNTs at a shorter wavelength (254 nm) leads to 2-thiophanyl radicals 8, which derivatize SWCNTs by covalent attachment. Pyrolysis of the resulting "sulfurized SWCNTs" affords a mixture of organosulfur compounds, including thiophene formed by dehydrogenation. An unknown additional mechanism causes high TGA weight loss and a large incorporation of sulfur.

Synthesis of Dy doped Co–Zn ferrite by sol–gel auto combustion method and its characterization

Dysprosium doped Co–Zn ferrites were synthesized by sol–gel auto combustion method. These synthesized compounds were characterized by using XRD, SEM, FTIR, EDS, TGA-DTA and TEM. TGA weight loss in the region of 100–200°C and this loss is due to autocatalytic oxidation reduction reactions of nitrates with glycine. The composition Co0.5Zn0.5Fe2−xDyxO4 (x=0.075) shows fibrous reticulated mesh like morphology. The average grain size increases with increasing the Dy content in the Co–Zn ferrite. The XRD study of Dy doped Co–Zn ferrite shows in Cubic spinel phase. Particle size obtained from TEM analysis was found to be 30–40nm. The FTIR spectra showed the characteristic of two strong absorption bands at 560cm−1 corresponds to intrinsic stretching vibrations of the metal at the tetrahedral site and lowest band is observed at 455cm−1 corresponds to octahedral site.

Atom Transfer Rearrangement Radical Polymerization of Diamminebis( 2,4,6-trihalophenolato)copper(II) Complexes in the Solid State

The synthesis of the poly(dichloro- or dibromophenylene oxide)s was achieved by the thermal decomposition of diammine-bis(2,4,6-trihalophenolato)copper(II) complexes in the solid state by atom transfer rearrangement radical polymerization. The thermal decomposition was performed either at different temperature ranges, 110 - 250 °C, for 3 h, or at the maximum conversion temperature for different time intervals, 3 - 48 h. Maximum yields of polymers were obtained at 190 °C and 3 h. The polymers were characterized by FTIR, 1H and 13C NMR spectroscopy, SEM, TGA and molecular weight determination by viscometrical methods. All the polymers were rigid, having high Tg values between 178 and 189 °C. Only small amounts of Cu were detected by AAS.

Post-mortem characterization of coke-induced deactivated alumina-supported Co–Ni catalysts

The physicochemical properties of used catalysts obtained from propane steam reforming under steam-to-carbon (S:C) of 0.8 and 1.6 at operating temperatures of 773–873 K were investigated using BET, H 2 chemisorption, total organic carbon (TOC) content analysis, XRD, TEM, as well as carbon reactivity analysis via gravimetric temperature-programmed (TPO–TPR and TPR–TPO–TPR) runs. These independent fingerprinting techniques provided good agreement on the nature and quantity of carbon deposited as a function of steam-reforming history. It is shown that the surface area and bulk phase characteristics were not irreversibly damaged by carbon deposition. However, TOC, XRD and TGA weight analyses showed a higher carbon content at lower S:C ratio and temperature. The weight derivative profiles for TPO and TPR suggest two types of carbon phases—atomic C α and naphthalenic C β . The deactivation-causing C β was observed in the TEM micrographs as thick layers of filamentous carbon. This was corroborated by the crystalline carbon peak recorded in the XRD pattern. The study further showed that regeneration via reductive–oxidative carbon removal was more efficient than an oxidative–reductive route since the former produced a regenerated Co–Ni catalyst without substantial loss in surface properties (e.g., BET area, percent metal dispersion and active particle size). Carbon removal kinetics was attended by a relatively low activation energy (54– 58 kJ mol - 1 ) symptomatic of primary carbon deposition on metal sites. Solid-state rate data for the oxidative regeneration were adequately fitted by an Avrami–Erofeev reaction-order model.

Simple methods for calibrating IR in TGA/IR analyses

This work reports the calibration of the IR signals from TGA effluent gas using decomposition of solids and evaporation of liquids. The IR signal separates the TGA weight losses for quantitation, and allows a successful deconvolution of the TGA data where several compounds are evolving from the TGA at the same time. It is unnecessary to heat the transfer lines and IR cell as long as the effluent has some volatility at ambient temperature. A DSC pinhole pan makes a very effective device for the calibration of low boiling components and produces calibration data equivalent to that achieved by decomposition of solid substrates. The value of the technique is demonstrated by quantitation of overlapping components in the TGA effluent.