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This study examined the combustion characteristics and kinetics of coal samples treated with imidazole-based ionic liquids (ILs), namely, [Emim][BF4], [Bmim][BF4], [Bmim][NO3], and [Bmim][I], under oxidation. The oxidation of the coal samples was investigated using thermogravimetry (TG) at heating rates of 4.0, 6.0, 8.0, and 10.0 °C·min−1. The results for the IL-treated samples revealed that the composite index S (representing the ignition, combustion, and burnout properties) decreased and Hf (representing the rate and intensity of the combustion process) increased with high correlation coefficients. The characteristic temperatures of the maximum oxidization mass gain (T2), ignition point (T3), maximum mass loss rate (T4), and burnout point (T5) increased by 13.1 ± 0.5, 9.2 ± 0.5, 21.5 ± 0.5, and 35.9 ± 0.5 °C, respectively. At T3 and the maximum mass loss rate, the release of CO and CO2 was further altered, suggesting that the C O functional groups were damaged or oxidized. The results of the Ozawa-Flynn-Wall kinetic equation used to determine the apparent activation energy (Ea) of coal samples revealed that the Ea of the treated samples increased. The reaction rate constant characterizes the effect of Ea and pre-exponential factors (A), and the results showed that ILs can weaken the reaction process at low temperatures (

Ionic liquids (ILs) have numerous properties with a wide range of applications as an advanced or specialized material. Mixtures of ILs can further optimize their correlative properties. In this study, the thermal stability of imidazolium-based IL binary mixtures was evaluated by alternating the compound mode and molar fraction (3:7, 5:5, and 7:3) of parent ILs. We found that the thermal stability of the mixtures considerably decreased through a three-step decomposition for specific compound modes. To understand the thermal behaviors of the IL binary mixtures, we argue that the thermal stability of the IL binary mixtures depended on which compounds the ions in the mixture constituted, and that equal molar fractions are deserved to notice for designing IL mixtures. The results of this study can help in the design of relatively stable IL mixtures for proactive loss prevention in the subsequent industrial applications.

Ionic liquids (ILs), as a type of salt that is liquid at room temperature, break the entrenched views on salt when it was proved that some of them could be ignited. In this research, an innovative method was used to evaluate the thermal stability of such special salts and speculated their ignition mechanism based upon gas analysis. Four typical representative imidazole ILs (BMIMBF4, BMIMDCN, BMIMNO3, and BMIMOAc) were selected, and their thermal decomposition characteristics and thermal effect were obtained by simultaneous thermogravimetric analyser (STA) and differential scanning calorimetry (DSC), respectively. Furthermore, their decomposition products were investigated by thermogravimetry coupled with Fourier-transform infrared spectroscopy (TG-FTIR). It is noteworthy that they behaved diversely in DSC experiments and exhibited a radically different thermal effect in their decomposition. In addition, there exists positive feedback in the mechanism of the exothermic phenomenon of selected ILs in the air. Nevertheless, TG curves of four selected ILs were almost the same under air or nitrogen conditions. Series TG-FTIR experiments confirmed that the initial decomposition products of BMIMBF4 and BMIMDCN under air or nitrogen are extremely different. The decomposition products of BMIMNO3 and BMIMOAc in the air atmosphere have more oxidative products than nitrogen. The results denoted that the thermal decomposition mechanism of the four selected ILs in the air were the same as under nitrogen. The reducibility of the decomposition products induced the peculiar thermal effects of these imidazole ILs under the different gas environments. This study was innovative in researching the thermal effect and mechanism of imidazole ILs’ decomposition and provided certain safety guidance for the process safety and loss prevention of imidazole ILs.

The protonated amine modified-lotus stem powder (PAM-LSP) can be used to eliminate Reactive Red 120 (RR-120) from an aqueous solution as a potential adsorbent. Different operating variables like pH, agitation speed, adsorbent dosage, contact time, temperature, and initial RR-120 concentration were highly dependent on the adsorption process. FE-SEM (morphological), EDX (elemental), FTIR (functional), and N2 adsorption/desorption isotherms (texture properties) have been conducted to detect the adsorptive characteristics of LSP and PAM-LSP. To analyze the equilibrium data, non-linear isothermal models of Langmuir, Temkin, D-R (Dubinin-Radushkevich), and Freundlich were used. Among the four isothermal models, as shown by lower χ2 value (19.85), higher R2 (0.9956), the Langmuir matches the experimental data better than others. The experimental data were examined using non-linearized kinetic models of PFO (pseudo-first-order) and PSO (pseudo-second-order) and were better represented in the PSO model (R2 > 0.9902). It is noticeable that the adsorption of the RR-120 on PAM-LSP was a feasible, spontaneous, and endothermic physisorption process based on the calculated thermodynamic parameters like ΔHo (10.07 kJ/mol), ΔSo (33.8 J/mol K), ΔGo (-0.0539 to −1.3816 kJ/mol), Ea (5.9 kJ/mol), and S* (0.0043). Desorption experiments were performed with some selected eluents and the best desorbing eluent was found between NaOH, NaHCO3, NaCl, HCl, HNO3, CH3COOH, and DIW. The PAM-LSP was used without significant adsorptive performance loss for five adsorption/desorption cycles. Electrostatic interactions between the RR-120 dye molecules and the PAM-LSP are responsible for the primary adsorption mechanism. To remove RR-120 from wastewater, the eco-friendly prepared PAM-LSP was considered a highly recyclable and efficient adsorbent.

Water contamination through textile dyes, metal depositions, and industrial wastes such as coal combustion residues especially coal fly ash (CFA) putting an enormous strain on dwindling planets water resources. Several characterization techniques, such as XRF, XRD, BET, SEM, and FT-IR, were performed to test the inherent properties of raw CFA and the product zeolite (AlPO4-5). The fusion ratio (CFA: NaOH) substantially enhanced the specific surface area of the zeolite (219.3 m2/g) compared to raw CFA (6.27 m2/g). The hydrothermal treatment greatly altered the molar ratio of Si/Al from 3.18 (CFA) to 2.11 (AlPO4-5) suggesting higher crystallinity of the product. Further, AlPO4-5 molecular sieve was tested its ability in separation of cationic Rhodamine 6G dye (R 6G), and Cr (VI) from liquid phase via batch mode adsorption process. The results indicated that the optimal adsorption conditions were (pH = 7 for R 6G; pH = 2 for Cr (VI); temperature 303 K for both adsorbates; dosage (0.05 g/30 mL–R 6G; 0.1 g/30 mL–Cr(VI); and residence time; 120 min–R 6G, 180 min–Cr (VI) respectively. Further, the Langmuir isotherm model suits well reporting maximum adsorption capacities (qm) as 208.61 (mg/g)–R 6G; 97.32 (mg/g)–Cr (VI)), and best fits to the pseudo-second-order kinetic models. The thermodynamic aspects exhibit the spontaneous and endothermic nature of R 6G dye, and Cr (VI) metal sorption onto AlPO4-5 zeolite. From the desorption studies, alkaline eluent 0.1 M NaOH showed better performance in recovering 89.4%, 91% of adsorbent from R 6G dye, and Cr (VI) solutions respectively. Lastly, the reusability studies confirmed that the adsorbent (AlPO4-5) had the potential up to three cycles (R 6G), and it is confined to two cycles in case of Cr (VI) metal solution.

Thermal decomposition temperature (Td) is a vital feature to assess the thermal hazard of ionic liquids (ILs). In this approach, a statistically significant quantitative structure-property relationship (QSPR) model was developed to forecast the Td of imidazolium ILs merely derived from their molecular structures. The new proposed norm indexes were employed to characterize not only the structural characteristics of anions and cations but also the interaction between anions and cations. The genetic algorithm-based multiple linear regression (GA-MLR) method was adopted to choose the best set of norm indexes that oblige a prominent contribution to the Td of imidazolium ILs. The results prediction model was obtained from a multilinear equation with thirteen variables, as consisting of three cationic descriptors, seven anionic descriptors, and three interaction descriptors. The squared correlation coefficients (R2) and the root-mean-squared error (RMSE) of the resulting model are 0.895 and 21.626, respectively. The developed model was then rigorously verified by various validation methods, and thoroughly extensively compared with formerly circulated published models. The results showed satisfactory sturdiness and accountability of the model, which would be considered to be able to forecast the Td of imidazolium ILs and provide some guidelines for designing as well manufacturing safer ILs with better thermal stability.

The chemical structure and morphological of lignite treated with four imidazole ionic liquids (ILs), namely [BMIM][BF4], [BMIM][NO3], [BMIM][I], and [EMIM][BF4], was characterized through scanning electron microscopy and X-ray diffraction. Furthermore, the exothermic properties of the oxidation process at low temperatures ( [BMIM][NO3]-tc > [BMIM][I]-tc > [EMIM][BF4]-tc > [BMIM][BF4]-tc. The IL destroys the chemical structure of the coal, resulting in a decrease in the activity of the coal, which is manifested by an increase in apparent activation energy.

Nitrocellulose (NC), a highly flammable material, has caused multiple runaway explosions worldwide. Although the thermal stability of NC blended with incompatible materials has been extensively studied, no research on the suppression of spontaneous combustion by using a humectant has been conducted. Ionic liquids possess superior characteristics and have been employed as flame retardants. In this study, 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF6]) was selected as a humectant of NC. First, a series of experiments were conducted to determine the feasibility of the study. Scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy were used to investigate the microstructure, nature, and functional groups of [Bmim][PF6] that affect NC. Next, the inhibition of [Bmim][PF6] on NC was confirmed through an intuitive heating test. Subsequently, the thermal stability of three types of NC systems was evaluated, and the action of [Bmim][PF6] was analysed. Thermokinetic parameters were analysed using differential scanning calorimetry, and the apparent activation energies were evaluated using the Starink method and Friedman method. The time to maximum rate under adiabatic conditions and self-accelerating decomposition temperature were calculated using simulations. Finally, the decomposition of the NC systems was analysed using thermogravimetry-infrared spectroscopy, which elucidated the reasons underlying [Bmim][PF6]-induced inhibition of the spontaneous combustion of NC.

Ionic liquids (ILs), or ambient-temperature molten salts, comprise ions solely and exhibit several specific liquid-like properties. Research in this area has developed promptly and extensively. Sufficient thermal stability is required when ILs are applied as electrolytes, fire retardants, catalysts, or solvents. Because the thermal decomposition temperature (Td) indicates the maximum processing temperature before undergoing chemical decomposition, it is among the most crucial parameters characterizing their thermal hazard. Apart from actual experimentation, the quantitative structure-property relationship (QSPR) methods have already been applied in forecasting the Td of ILs. In this paper, the possible means of structurally characterizing ILs are comprehensively reviewed. Advances in the QSPR method for predicting IL properties are highlighted, and existing models predicting the Td of ILs are presented. The need for developing new interaction descriptors of ILs for future applications is also emphasized.

Azo-peroxyester, a multifunctional elemental energetic material, has low efficiency when indirectly acting on the target product in a reaction. If azo-peroxyester is dissolved in an appropriate solvent, the yield is greatly improved. With the aim of perfecting the safety of diethyl azodicarboxylate (DEAD) in industrial process applications, this study evaluated the inherent safety of DEAD when dissolved in different reagents by using differential scanning calorimetry and a thermal activity monitor III. The thermokinetic parameters, exothermic onset temperature (To), time to maximum rate under isothermal conditions (TMRiso), and apparent activation energy (Ea), were determined in order to reveal factors influencing the reaction mechanism. Comparing with pure DEAD, T0 was lower when DEAD was dissolved in three ionic liquids: 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium tetrafluoroborate, and 1-butyl-3-methylimidazolium bis(trifluoromethyl)sulfonyl)imide. Additionally, Ea and TMRiso were considerably higher, indicating there was an improvement in both efficiency and thermal safety of DEAD for the reaction process. These results support the applications of DEAD in industrial process safety, and set a foundation for future laboratory investigation.

Modern refined lubricants have several advantages over their predecessors. However, numerous modern lubricants are environmentally unfriendly, and professional technicians must dispose of lubricant by-products at recycling plants. The primary problem of lubricant by-products is their susceptibility to accidental fire. Both environmental pollution and lubricant-related fire hazards affect the lives of people who live and work near lubricant recycling plants. To examine additives that might alleviate fire hazards, this study tested three types of synthetic engine lubricants with an additional lithium-based salt—LiBF4. The values of mass loss and differential mass loss were obtained through thermogravimetry. The differential isoconversional (Friedman method), Flynn–Wall–Ozawa, and ASTM E698 methods were applied to calculate the apparent activation energy (Ea). Results revealed that LiBF4 could improve the efficiency of engine lubricants. Additional tests were conducted using periodic temperature fluctuation and isothermal simulation models to predict changes during real-world use. Fourier transform infrared spectroscopy showed that LiBF4 could suppress the generation of carbonyl groups (C O) after being mixed with a lubricant.