Thermal Kinetic Parameters Research Articles

Identification and quantification of soil water components in kaolin by thermogravimetric and kinetic analysis

Different types of soil water, such as bound water and capillary water, have distinct effects on the physicochemical and engineering properties of soils, particularly unsaturated clayey soils. Therefore, it is crucial to develop an accurate and physically meaningful experimental method for identifying and quantifying these components. This study pioneers the use of a multi-step kinetic model to identify and quantify different soil water components across a wide range of relative humidity (RH) using thermogravimetric analysis (TGA) data. To validate the determined kinetic parameters (i.e., activation energy, preexponential factor, and reaction model) and the identification and quantification results of soil water components, TGA with multiple heating rates, nitrogen adsorption method, cation exchange capacity measurement, and nuclear magnetic resonance (NMR) were performed on kaolin samples equilibrated under various RH conditions. These experimental results cross-validate the superior performance of the kinetic model in determining soil water components and predicting the thermal desorption behaviors of soil water. Based on the cross-validation results, the soil water components obtained from the kinetic analysis are further identified as tightly-bound, loosely-bound, and capillary water, which exhibit variations consistent with empirical soil water isotherm models. The T2 cutoff value between bound and capillary water is determined to be 1.79 ms based on TGA and NMR results. The determined thermal kinetic parameters of different soil water components can exhibit their distinct retention mechanisms. The method and results in this study provide a new perspective on identifying different soil water components, as well as understanding the mechanism of soil-water interactions in unsaturated soils.

Survival of lactic acid bacteria species in Filipino donor milk subjected to different heating temperatures

This study aimed to characterize the behaviors of a cocktail of lactic acid bacteria (LAB) isolated from human donor milk after subjecting to processing at different temperatures. The isolates (n = 12) were identified using 16S rRNA sequencing prior to the propagation and challenge studies. BLAST comparisons revealed that the isolates were Streptococcus spp., Lactobacillus spp., and Enterococcus spp. (% Identity 91.20–98.67%). At an initial inoculation level (8.0 log CFU/ml), the isolates exhibited a non-linear inactivation curve in all temperatures. In the initial logarithmic-linear phase, a decreasing D-value that ranged from 1.70 to 0.20 min was observed with increasing heating temperatures (55 °C, 57 °C, 60 °C, and 63 °C). Microbial load reduction in this initial phase (LR1) also increased (3.31–5.42 log CFU/ml). Moreover, the time necessary to reach LR1 (tLR1), prior to the inactivation curve inflection to tailing, generally decreased. During tailing, minimal to no additional microbial load changes were observed. Total reduction (TLR) increased (3.32–5.42 log CFU/ml), the time it took to reach TLR (tTLR) decreased (60.00–40 min), and the survivor population decreased (4.83–2.63 log CFU/ml) with increasing temperature. The study was able to establish the thermal challenging behaviors and kinetic parameters of a cocktail of lactic acid bacteria (LAB) in human donor milk with known composition and physicochemical properties. The inactivation kinetic parameters were determined from the curves and significantly varied with increasing heating temperature. This study provides a basis for evaluation and possible improvement of the Holder pasteurization (HoP) protocols for human donor milk, specifically temperatures below HoP that allow for keeping the milk biologically active without compromising quality.

Protection Function and Mechanism of Rosemary (Rosmarinus officinalis L.) Extract on the Thermal Oxidative Stability of Vegetable Oils.

Rosemary (Rosmarinus officinalis L.) extract (RE) is one of the most efficient natural antioxidants and can significantly inhibit oil oxidation during storage or heating. The present study determined the protective capacity and mechanism of RE on the thermal oxidative stability of different vegetable oils by adding RE (70% carnosic acid) to five types of vegetable oils (soybean oil, rapeseed oil, cottonseed oil, rice bran oil, and camellia oil) and measuring the physicochemical indices (fatty acid composition, tocopherol content, total phenolic content, and free radical scavenging capacity), induction period, and thermal oxidative kinetic parameters. The relationships between the antioxidant capacity and thermal stability parameters were determined. The results show that, compared with artificial antioxidants, RE significantly increased the free radical scavenging capacity, induction period, and activation energy (Ea) of thermal oxidation, decreasing the thermal oxidation reaction rate (k) of all vegetable oils, especially rice bran oil. A Spearman correlation analysis showed that the induction period (IP) and Ea showed a significant positive correlation, the combination of which effectively reflected the efficiency of antioxidants and explained the inhibition mechanism of RE towards oil thermal oxidation.

Synthesis, Thermogravimetric Analysis, and Kinetic Study of Poly-N-Isopropylacrylamide with Varied Initiator Content.

The thermal decomposition and kinetic parameters of four polymers, PN-1, PN-05, PN-01, and PN-005, were determined by thermogravimetry (TGA/DTG) under non-isothermal conditions. N-isopropylacrylamide (NIPA)-based polymers were synthesized by the surfactant-free precipitation polymerization (SFPP) with different concentrations of the anionic initiator potassium persulphate (KPS). Thermogravimetric experiments were carried out in the temperature range of 25-700 °C at four heating rates, 5, 10, 15, and 20 °C min-1, under a nitrogen atmosphere. Poly NIPA (PNIPA) showed three stages of mass loss during the degradation process. The thermal stability of the test material was determined. Activation energy values were estimated using Ozawa, Kissinger, Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS), and Friedman (FD) methods.

Coupling effect on the thermal hazard assessment of hazardous chemical materials via calorimetric technologies and simulation approaches

The coupling effect of heat absorption and release exists in the thermal decomposition of a few chemical materials. However, the impact of the above coupling on thermal hazard assessment is not considered in the literature studies. In this work, nitroguanidine (NQ) and 1,3,5-trinitro-1,3,5-triazine (RDX) are selected as representative materials to explore the influence of the coupling effect on the thermal hazard assessment of chemical materials. The linear heating experiments of NQ and RDX are carried out by a microcalorimeter and synchronous thermal analyser. The thermal decomposition curves are decoupled by advanced thermokinetics software. The thermal decomposition and kinetic parameters before and after decoupling are calculated. The results of TG experiment show that both NQ and RDX began to lose mass during the endothermic stage. The endothermic melting and exothermic decomposition of NQ and RDX are coupled within this stage. The coupling effect has different degrees of influence on its initial decomposition temperature and safety parameters. Compared with the parameters in the coupling state, the initial decomposition temperature and adiabatic induction period after decoupling decrease. The self-accelerating decomposition temperature increases, and internal thermal runaway time decreases. In the thermal hazard assessment of chemical materials with coupling effects, the calculated parameters after decoupling should be taken as an important safety index.

Thermodynamic parameter analysis of water vapor adsorption process of fly ash concrete material

Experimental research on water vapor adsorption performance of concrete with different class Ⅱ fly ash contents is carried out in this paper. Time-varying response curves of water vapor adsorption of fly ash concrete in five different humidity environments were obtained. According to the empirical formula of the thermodynamic parameters of water vapor adsorption of cement-based materials, the thermodynamic parameters of the water vapor adsorption process of fly ash concrete materials are calculated. The calculation method of the thermal kinetic parameters of water vapor adsorption for fly ash concrete materials is proposed; Influence of different fly ash contents with 10%, 20% and 30% mass percentage of cement and water-cement ratio on the water vapor adsorption characteristics of concrete materials is analyzed; The error between the second-layer adsorption energy and the condensation enthalpy of water vapor is calculated, and the rationality of the approximate calculation is analyzed. It is noted that (1) Water vapor adsorption characteristics of concrete materials are related to the water-cement ratio. With the water-cement ratio decreases, the adsorption capacity of concrete material increases. (2) Reasonable formula for calculating the number of saturated adsorption layers n of water vapor suitable for concrete materials is recommended. (3) Taking the condensation enthalpy of water vapor as the adsorption enthalpy of the second layer and subsequent layers reasonable to determine the dynamic parameters of the water vapor adsorption process of concrete.

Thermal stability of NaOH modified rice husk fiber-reinforced polylactic acid composites: Effect of rice husks and clay loading

This work studied the synthesis, thermal behaviour and combustion properties of clay/modified rice husk fiber-reinforced PLA composites. Raw rice husks, NaOH modified rice husks, clay and Polylactic acid (PLA) were used as raw materials. SEM analysis revealed that at 1 wt% clay and 10 wt% rice husks loadings, bonding was enhanced between filler/fiber and PLA matrix. Composites' respective tensile strengths and Young's moduli varied from 21.17 to 29.19 MPa and 1.70–2.13 GPa (raw rice husks) as well as from 21.15 to 32.44 MPa and 1.64–1.97 GPa (modified rice husks). Composites' ignition and burnout temperatures ranged from 317.56 to 364.48 °C and 380.28–415.07 °C respectively. Flammability indices, combustion characteristic indices As well as mean reactivities varied from 1.45 × 10−5 to 2.00 × 10−5%/min°C2, 0.55 × 10−8 to 0.86 × 10−8%2/min2°C3 and 4.06 × 10−3 to 6.97 × 10−3%/min/°C respectively. Adding rice husks to the PLA matrix led to an increase in the melting temperatures of the accruing composites. TGA showed that incorporation of clay and rice husks resulted into delayed weight loss by 10–20% and increased char residues to 6.38−16.96%, hence higher thermal stability than neat PLA. Addition of rice husks inhibited neat PLA's pyrolysis process. PLA composites' activation energy ranged from 112.95 to 125.87 kJ/mol, which is significantly higher than that of the neat PLA (104.80 kJ/mol). These findings revealed that thermal stability, kinetic parameters and combustion characteristics of PLA composites are better, compared to some conventional polymer products.

New Heterocyclic Organo-Chalcogenide Compounds: Synthesis, Physicochemical Characterization, and Evaluation of Anticancer Activity against Breast Cancer Cells

This work aimed to synthesize, characterize and evaluate the thermal stability of new sulfur and selenium organochalcogenide derivatives and to test the cytotoxic activity against breast adenocarcinoma cell line (MCF-7) through conducting MTT assay and AO/EB dual staining-technique. Two series of ten organo-chalcogen compounds: 4-(substituted)phenylthiomorpholine-3,5-dione and 4-(substituted)phenylselenomorpholine-3,5-dione were prepared by the reaction of Na2S·3H2O and NaHSe with N-(substituted)phenyl-2-chloro-N-(2-chloroacetyl)acetamide, respectively, under nitrogen atmosphere to give the corresponding cyclic chalcogenide ligands. All new compounds were characterized by melting point, FTIR, elemental analysis, UV-Visible, 1H-NMR and 13C-NMR. Meanwhile, TG/DTA analysis of some of these ligands was conducted to evaluate the thermal stability, kinetic, and characteristic thermodynamic parameters. Absorption spectroscopy was used to investigate these compounds with human DNA. The experimental results investigated a hypochromic effect via intercalation binding mode. The role of the prepared ligands in breast cell lines has been investigated by conducting MTT assay via spectroscopic techniques on HBL100 and MCF-7, normal and cancer breast cell lines, respectively. Cell death was seen after AO/EB dye staining method employing the fluorescence microscopy technique. The results revealed that these compounds possess cytotoxic activity on the MCF-7 and HBL-100 cell lines at a fixed concentration.

Improved thermal stability of roselle anthocyanin by co-pigmented with oxalic acid: Preparation, characterization and enhancement mechanism

The enhancement effects of co-pigmentation on thermal stability of roselle anthocyanin extract (RAE) were investigated. The introduction of organic acids maintained color stability of RAE, and RAE co-pigmented with oxalic acid (OA) presented less color fading rates (19.46 ± 0.33 %) and higher redness (41.33 ± 3.51). Subsequently, suitable co-pigmentation concentration (OA:RAE = 1:2) was obtained regarding with lower ΔE (48.70 ± 2.36). Then, improvement behaviors of co-pigmentation on OA-RAE were evaluated. Results demonstrated that OA-RAE exhibited better thermal stability, as manifested by larger retention rates and more favorable thermal degradation kinetic parameters. Furthermore, both molecular docking simulation and experimental structural characterization revealed that hydrogen bonds and other non-covalent bonds made up the main parts of molecular interactions, leading to formation of stable binary complex. As a result, the aromatic ring of RAE was protected. In conclusion, the co-pigmentation of RAE via introduction of OA was effective in stability enhancement due to the generation of molecular bindings.

Application of multi-channel in situ infrared spectroscopy: the case of PVB thermal aging.

Thermal kinetic parameters are important for establishing the relationship between the aging process, time, and temperature, which would help predict the thermal aging lifetime and stability in the application of polymer materials. We developed a multi-channel in situ detecting device, which provided an efficient method for IR spectrum measurement. The thermal aging process of polyvinyl butyral (PVB) at several constant temperatures (100 °C, 110 °C, 120 °C, 135 °C, and 150 °C) had been studied by the multi-channel in situ infrared reaction device. The kinetic parameters (Eα) were calculated from the absorbance intensity of -C-O-, -C[double bond, length as m-dash]O, -CH3, and -OH. The -OH proved to be the active site of PVB during thermal aging, and a possible thermal aging mechanism of PVB was proposed. We proved the method using a combination of a multi-channel in situ reaction device and FTIR was suitable to study the aging mechanism and kinetics of polymers.

Overriding Investigation on Strengthening of Thermal Stability of Torrefied Pigeon Pea Stalk and Kinetic Compensation

This article aims to evaluate the pyrolytic behavior of torrefied biomass in order to resolve the logistic issue of the biomaterial and utilize it during idle time. In order to that, the thermal treatment of the raw pigeon pea stalk was done up to 250℃ in a reactor in an inert environment. The obtained solid biomaterial was subjected to the thermogravimetric analysis for four various heating rates (10, 20, 30, and 40℃/min) to investigate the changes occurring in thermal behaviour and kinetic parameters over the raw material. The deconvolution analysis of the thermogravimetric signals leads the study to an overriding investigation on thermal stability of the intrinsic bioconstituent. In addition, the kinetic triplet and thermodynamic parameters were estimated by employing the ICTAC recommended Ozawa-Flynn-Wall isoconversional method. The computed average activation energy level of the torrefied biomaterial (229 kJ/mol) was registered significantly higher than the raw pigeon pea stalk (139 kJ/mol). Also, the changes registered in thermodynamic parameters such as ΔG, ΔH and ΔS give a beneficial sign on the thermal stability of the existing bioconstituents. Torrefaction of the pigeon pea stalk enhances the kinetics and thermodynamic balancing of the biomaterial. The thermally established biomaterial can be stored for a longer period and it can utilize as the bioenergy generating feedstock during idle periods.

Studies on Biosynthesis of Chiral Sulfoxides by Using P450 119 Peroxygenase and Its Mutants

AbstractVarious alkyl‐aryl and heteroaromatic sulfides were catalyzed by P450 119 peroxygenase in the presence of TBHP. P450 119 mutants were used to improve the yield and enantioselectivity of the sulfoxidation. The P450 119 mutation at 153 was found to efficiently improve activity, specificity and enantioselectivity of the sulfoxidation of heteroaromatic sulfides up to 93 % yield and 57 % ee for the first time, meanwhile its thermal stability, kinetic parameters and molecular docking were studied. The experimental results provide a potential method for the biosynthesis of chiral sulfoxides, especially for asymmetric oxidation of heteroaromatic sulfides, by enduring evolution of thermal‐stable P450 119 peroxygenase.

PVC/PVP/SrTiO3 polymer blend nanocomposites as potential materials for optoelectronic applications

This paper presents, for the first time, the preparation and study of the thermal decomposition and optical properties of PVC/PVP/SrTiO3 polymer blend nanocomposites. The polymer films were characterized using X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FTIR), Raman, thermogravimetric analysis (TGA), and optical spectroscopy techniques. XRD spectra indicated semicrystalline structure of the PVC/PVP polymer blend and revealed cubic crystal structure of the SrTiO3 nanoparticles. The lattice constant of SrTiO3 was found to decrease from 2.79 to 2.75 Å upon increasing the concentration of the SrTiO3 nanoparticles in the blend to 0.6 wt%. The FTIR and Raman spectra revealed the strong interaction between PVC/PVP polymer blend and SrTiO3. The TGA analysis showed a slight enhancement of the polymer blend thermal stability. Moreover, the thermal kinetic parameters, such as activation energy, entropy and Gibbs free energy, of the polymer nanocomposites were lower than those of the pure PVC/PVP blend counterpart. The addition of SrTiO3 increased the optical absorption, energy gap, and linear refractive index. Furthermore, the optical susceptibility and nonlinear refractive index were significantly improved. For all polymer blends, a fluorescence peak appeared at a wavelength of 485 nm. These outcomes qualify the PVC/PVP/SrTiO3 polymer blend nanocomposites for optoelectronic applications.

Thermal decomposition characterization and kinetic parameters estimation for date palm wastes and their blends using TGA

TGA has been used to evaluate the thermal degradation profiles and kinetic parameters for the pyrolysis of date leaves, date seeds, and leaf stems and their blend at various heating rates (β) in N2. Using Kissinger–Akahira–Sunose (KAS), and Ozawa-Flynn-Wall (OFW), kinetic parameters like activation energy (E) and frequency factor (A) were estimated. The diffusion, reaction order, and power law models were used to estimate the frequency factors based on the (E) values obtained from the OFW and KAS approaches. Thermal degradation profiles showed two major loss processes: volatilization of cellulose, hemicelluloses, and lignin; and slow oxidation of the residual char. The findings demonstrated that as β increased, the TG profiles shifted to higher temperature ranges. The date palm's decomposition was not favourably reflected by the high (ΔGav) values obtained. The high (ΔSav) values obtained using OFW compared to KAS confirm these materials' high reactivity. The average activation energies (Eav) for the different parts of the date palm wastes ranged between 86 and 117 kJ/mole as predicted by the KAS method, while they were between 92 and 120 kJ/mole using the OFW method. The calculated frequency factor (A) values, evaluated by the KAS and the OFW methods, ranged between 0.0 and ∼ 0.8 × 1019min-1. The difference in (Eav) values between the KAS and OFW techniques is no greater than 8 kJ/mole. For the diffusion models of DSW, DL, and Blend, the best frequency distribution profiles are essentially normal, and the blend exhibits high frequency (A) values in a relatively constrained range of (α). That denotes quick and efficient pyrolysis. The pyrolysis index (CPI) significantly increased as β increased, indicating that pyrolysis was profitable at high heating rates. The volatile release index (Ddev) increases significantly with increasing (β) value, showing that volatiles was easier to release at a high heating rate.

Thermal Aspects of Kumada Rearrangement in Symmetrical and Asymmetrical Polysilanes-Interdependence of Molecular Structure, Thermal Degradation, and Stability

Thermal degradation behavior, exothermic patterns, and kinetic parameters of symmetrically/asymmetrically substituted polysilanes during the kumada thermal rearrangement in the temperature range of 100–450 °C, were investigated applying thermogravimetric (TGA) and differential scanning calorimetric (DSC) techniques. Three kinds of polysilanes, viz., Polydimethylsilane (PDMS), Polydiphenylsilane (PDPS) and Polymethylphenylsilane (PMPS) were synthesized through Wurtz/Wurtz-Fittig polycondensation. As-synthesized polysilanes were then characterized by FT-IR, CHNO, and TGA–DSC techniques. FT-IR spectra confirmed the presence of methyl, phenyl, and a combination of methyl-phenyl functional groups in PDMS, PDPS, and PMPS, respectively. From CHNO analysis, the chemical/empirical formula of PDMS, PDPS, and PMPS was found to be SiC2.01H6.25, SiC12.50H10.26, and SiC6.45H7.76, respectively. TGA results confirmed that PDPS was more thermally stable as compared to PDMS and PMPS. The kinetic parameters of polysilanes were determined by using isoconversional methods such as Ozawa and modified Kissinger–Akahira–Sunose (KAS) methods. The average value of activation energy for PDPS obtained from Ozawa and KAS methods was found to be 1078.49 and 1068.32 kJ/mole, respectively, which is very much higher as compared to that of PDMS and PMPS.

Identification, kinetics and thermodynamic analysis of novel β-galactosidase from Convolvulus arvensis seeds: An efficient agent for delactosed milk activity

The β-galactosidase was extracted and purified from 100 g of C. arvensis seeds using a variety of protein purification procedures such as ammonium sulphate fractionation, gel filtration, and finally chromatography on a cationic ion exchanger. The effects of metal ions, kinetics parameters, and glycoprotein nature were determined, as well as the optimal pH and temperature of the purified enzyme. With a high specific activity (72 units/mg), β-galactosidase was isolated to a 24-fold apparent electrophoretic homogeneity. The molecular mass of β-galactosidase was determined as monomeric, which was further confirmed by SDS-PAGE and MALDI-TOF/MS analysis, with a 45 kDa molecular weight. The enzyme has a Km of 0.33 mM and a Vmax of 42 μmol/min Lactose in milk was reduced by 38.5 and 70 % after 4 h of incubation with β-galactosidase from C. arvensis. The β-galactosidase thermal inactivation kinetic parameters ΔH°, ΔS°, and ΔG° were calculated, indicating that the enzyme undergoes significant unfolding events during denaturation. Using β-galactosidase from C. arvensis seeds, lactose hydrolysis in milk up to approx. 50 % was observed. The findings indicate the potential use of C. arvensis seeds for the production of low/delactosed milk for lactose-intolerant population.

Effect of Zeolite Catalyst on the Pyrolysis Kinetics of Multi-Layered Plastic Food Packaging

Pyrolysis is gaining more significance as a technology used to produce alternative fuels and chemicals. This study dealt with the catalytic pyrolysis of a realistic waste mixture of multi-layered plastic food packaging. The thermal behavior, kinetic parameters, and kinetic model of multi-layered plastic food packaging pyrolysis were determined to show its potential for process scale-up. In particular, we aimed to evaluate the effect of a ZSM-5 zeolite catalyst, modified with iron(III) oxide. The pyrolysis process on this decagonal structure was investigated using thermogravimetric analysis under nitrogen flow at four heating rates ranging between 40 and 600 °C. The kinetic study was conducted using the model-free isoconversional Friedman method as well as advanced statistical analysis to determine the reaction mechanism of the process. The thermal decomposition occurred in the range of 350–510 °C, with a mass loss greater than 90%. The kinetic study revealed a complex pyrolysis process, which consisted of three decomposition stages, diffusion, and Avrami-Erofeev reaction types. The activation energy values determined by the Friedman method rose with the degree of conversion, from 127 kJ mol−1 at 0.01 to 219 kJ mol−1 at 0.95. The doping of the catalyst lowered the activation energy of the reaction by 44% and 8% in the first and second stages, respectively, and increased the acidity of the zeolites, thus enhancing the reactivity on the surface of the catalysts. Lower activation energy meant less energy was required to heat the pyrolysis reactor since the onset temperature of sample decomposition was reduced.

Thermal Characteristics and Simulation of Enzymatic Lignin Isolated from Chinese Fir and Birch

Lignin is one of the main components of the plant cell wall, and the thermal properties of in situ biomass lignin are crucial for the multi-scale modeling of biomass properties and the thermodynamic modeling of lignin. In this study, high yields of double enzymatic lignin (DEL) were successfully isolated from softwood Chinese fir (Cunninghamia lanceolate (Lamb.) Hook.) and hardwood white birch (Betula platyphylla Suk.) to represent the in situ wood lignin. Their thermal properties, including specific heat capacity, thermal conductivity, thermal stability, and thermal degradation kinetic parameters, were tested and simulated. The results showed that Chinese fir DEL has different chemical structural units and thermal properties than birch DEL. The specific heat capacities of Chinese fir DEL and birch DEL at 20 °C were 1301 and 1468 J/(kg·K), respectively, and their thermal conductivities were 0.30 and 0.32 W/(m·K). Their specific heat capacity and thermal conductivity showed a positive linear relationship over a temperature range of 20–120 °C. Chinese fir DEL had a better thermal stability and a higher carbon residue than birch DEL. The average activation energy and pre-exponential factor changed with the conversion rate, and their relationships were simulated using linear or quadratic equations in the conversion rate range of 0.02–0.60. A second-order reaction function was found to be the best mechanism function for DEL thermal degradation.

Thermal characterization of urea phthalic acid material with thermal kinetic calculations

Urea Phthalic acid crystalline material was grown by slow evaporation method. The material was studied by Coats – Redfern method to calculate the thermal kinetic parameters. By analyzing the results, the nature of decomposition reaction of Urea Phthalic acid was investigated. The calculated values of thermal parameters indicate that the material is suitable for device fabrication applications.

Reconstructing the thermal structure of shallow crust in the Tono region using multi-OSL-thermometry of K-feldspar from deep borehole core

OSL-thermometry can be used to reconstruct the thermal structure in slowly denuded regions where infrared stimulated luminescence (IRSL) signals of samples obtained from deep boreholes are measured and evaluated with depth (e.g., 1.1–2.3 km depth, corresponding to ∼40–75°C; Guralnik et al., 2015a). Until now, only one study has explored this approach, using a target mineral of Na-feldspar. Therefore, in this study, we applied multi-OSL-thermometry to K-feldspar obtained from deep borehole core samples drilled at the Tono region, central Japan, which is a well-documented thermally stable crustal environment. The IRSL signals at 50, 100, 150, and 225°C (IR50, IR100, IR150, and IR225, respectively) were measured. When a combination of four isothermal holding temperatures (ITL) between 190 and 250°C was used for thermal kinetic parameter derivation, the inverted temperatures for the IR50 signals of the samples at a depth of ∼1 km (∼40°C) were most consistent with the in-situ temperature. However, the inverted temperatures for IR100, IR150, and IR225 signals were inconsistent with the in-situ temperatures even though the apparent geothermal gradients estimated from these IR signals are close to the modern geothermal gradient. These results suggest that the application of OSL-thermometry to K-feldspar in a borehole is useful to reconstruct the paleothermal conditions when adopting appropriate thermal kinetic parameters.