Thermal Activity Monitor Research Articles

Complex thermal evaluation for 2,2′-azobis(isobutyronitrile) by non-isothermal and isothermal kinetic analysis methods

Azo compounds are widely used in dyes, pigments, blowing agents, and initiators. Unfortunately, these compounds contain the bivalent –N–N– composition which might be cleavaged readily even under high ambient temperature. The self-accelerating decomposition might cause a runaway reaction and lead to a fire or explosion when the cooling system fails or other upsets occur. To investigate the thermal stability parameters of 2,2′-azobis(isobutyronitrile) with thermal hazard and mechanism, differential scanning calorimetry and thermal activity monitor III were applied with non-isothermal method and isothermal method to obtain onset temperature (T0), maximum temperature (Tmax), and heat of decomposition (ΔHd). Thermal stability parameters play a pivotal role in thermal analysis, leading particularly to complex evaluation of the inherently safer design during preparation, processing, transport, or storage. The results provide sufficient thermokinetic parameters for process safety in terms of proactive loss prevention program.

On the understanding and control of the spontaneous heating of dried tannery wastewater sludge

We studied the spontaneous heating of dried sludge produced by treating wastewater mainly originating from tanneries. Heating up to burning has been observed in the presence of air and moisture, starting at ambient temperature. To understand and prevent the process we combined chemical and morphological analyses (ESEM) with thermal activity monitoring in insulated vessels. Selective additions of chemicals, either to amplify or depress the reactivity, have been used to investigate and identify both the chemical mechanism causing the sludge self-heating, and a prevention or a mitigation strategy. FeS additions accelerate the onset of reactivity, while S sustains it over time. On the contrary, Ca(OH)2, Na2CO3, NaHCO3, FeCl2, EDTA, NaClO can limit, up to completely preventing, the exothermic activity. All the experimental evidences show that the reactions supporting the dried sludge self-heating involve the Fe/S/O system. The total suppression of the reactivity requires amounts of additives that are industrially incompatible with waste reduction and economics. The best prevention requires reduction or removal of S and Fe from the dried solid matrix.

Calorimetric Techniques Combined with Various Thermokinetic Models to Evaluate Incompatible Hazard of tert-Butyl Peroxy-2-ethyl Hexanoate Mixed with Metal Ions

tert-Butyl peroxy-2-ethyl hexanoate (TBPO), an organic peroxide broadly used as initiator for polymerization of ethylene, styrene, methyl methacrylate, and acrylonitrile, has the characteristic of triggering a highly exothermic reaction. Mixing with a contaminant, such as metal ions, may result in a runaway reaction and acceleration decomposition under an abnormal situation. We investigated how Cu2+, Ni2+, and Fe2+ individually affected the thermal decomposition of TBPO. Our aim was to explore the thermal hazard of TBPO mixed with metal ions by calorimetric techniques combined with thermokinetic models. We employed nonisothermal and isothermal calorimeters to determine various thermokinetic and safety parameters, including exothermic onset temperature (To), peak temperature (Tp), final temperature (Tf), heat of decomposition (ΔHd), and maximum heat flow (Qmax) by differential scanning calorimetry (DSC) and thermal activity monitor III (TAM III). Moreover, the isothermal and nonisothermal kinetic models we...

Effects of thermal runaway hazard for three organic peroxides conducted by acids and alkalines with DSC, VSP2, and TAM III

Organic peroxides (OPs) are commonly used in many industrial fields as initiators, hardeners, or cross-linking agents of radical polymerization with unsaturated monomers. However, OPs contain the bivalent OO structure which can incur exothermic decomposition that involves the splitting of the peroxide bond with a huge heat release and gas products that may cause an explosion under an uncontrollable upset. Differential scanning calorimetry (DSC) and thermal activity monitor III (TAM III) were used to analyze the thermal hazards and incompatibilities (H2SO4, NaOH, and Na2SO3) of cumene hydroperoxide (CHP), benzoyl peroxide (BPO), and dicumyl peroxide (DCPO). Dynamic and isothermal scanning tests were performed to compare the exothermic behaviors in a process. The thermokinetic data obtained via vent sizing package 2 (VSP2) were applied for evaluation, and the effects of thermal runaway hazard were compared for OPs conducted by acids and alkalis. These results are critically important in safer process design for producing and using OPs.

Studies of interparticle interactions among some l-α-amino acids and 1,2 (1,3)-propanediols in aqueous solution at 298.15 K

Mixing enthalpies of aqueous glycine, l-α-alanine, l-α-valine, l-α-serine. l-α-threonine and l-α-proline solutions and aqueous 1,2-propanediol and 1,3-propanediol solutions and their dilution enthalpies have been measured with a Thermometric-2277 Thermal Activity Monitor at 298.15K. Experimental data were treated according to the McMillan–Mayer theory and the heterogeneous enthalpic pairwise interaction coefficients (hxy) of the natural amino acids and propanediol molecules in aqueous solution were obtained. Combining the hxy coefficients of amino acids with glycol and glycerol in aqueous solution reported by our previous works, the effects of number and position of OH groups in polyalcohols on the interactions between them and amino acids are discussed in the terms of solute–solute interactions.

Characterization of dynamics in complex lyophilized formulations: I. Comparison of relaxation times measured by isothermal calorimetry with data estimated from the width of the glass transition temperature region

The purposes of this study are to characterize the relaxation dynamics in complex freeze dried formulations and to investigate the quantitative relationship between the structural relaxation time as measured by thermal activity monitor (TAM) and that estimated from the width of the glass transition temperature (ΔTg). The latter method has advantages over TAM because it is simple and quick. As part of this objective, we evaluate the accuracy in estimating relaxation time data at higher temperatures (50°C and 60°C) from TAM data at lower temperature (40°C) and glass transition region width (ΔTg) data obtained by differential scanning calorimetry. Formulations studied here were hydroxyethyl starch (HES)–disaccharide, HES–polyol, and HES–disaccharide–polyol at various ratios. We also re-examine, using TAM derived relaxation times, the correlation between protein stability (human growth hormone, hGH) and relaxation times explored in a previous report, which employed relaxation time data obtained from ΔTg. Results show that most of the freeze dried formulations exist in single amorphous phase, and structural relaxation times were successfully measured for these systems. We find a reasonably good correlation between TAM measured relaxation times and corresponding data obtained from estimates based on ΔTg, but the agreement is only qualitative. The comparison plot showed that TAM data are directly proportional to the 1/3 power of ΔTg data, after correcting for an offset. Nevertheless, the correlation between hGH stability and relaxation time remained qualitatively the same as found with using ΔTg derived relaxation data, and it was found that the modest extrapolation of TAM data to higher temperatures using ΔTg method and TAM data at 40°C resulted in quantitative agreement with TAM measurements made at 50°C and 60°C, provided the TAM experiment temperature, is well below the Tg of the sample.

Microcalorimetric study of growth of Lactococcus lactis IL1403 at low glucose concentration in liquids and solid agar gels

Growth of Lactococcus lactis IL1403 in liquid cultures and solid agar gels at different low glucose concentrations starting from 2gL−1 up to 10gL−1 with a stepwise increase by 1gL−1 was studied using thermal activity monitor TAM III. In parallel to calorimetric measurements the changes of glucose and lactic acid concentrations and pH of culture media were measured in order to obtain additional information for the interpretation of calorimetric power–time curves. The data obtained together with calculated heat yield coefficient YQ allowed to analyze the growth of bacteria in colonies in solid agar gels in detail. The variation of glucose concentration at low levels allows analyzing and describing growth deceleration phase and growth stopping mechanisms both in liquid cultures and in solid-state fermentations.

Isothermal hazards evaluation of benzoyl peroxide mixed with benzoic acid via TAM III test

Isothermal microcalorimetry can be used to investigate the thermokinetic parameters for reactive mechanisms. Benzoyl peroxide (BPO), a typical organic peroxide, undergoes an autocatalytic reaction under isothermal decomposition. It requires intrinsically safer design of preparation, manufacturing, transportation, storage, and even disposal. The scope of this study was to describe the exothermic reaction and reaction model of BPO and mixed with benzoic acid by the thermal activity monitor III (TAM III). The results showed the isothermal kinetic parameters, such as activation energy (E a), frequency factor (A), heat of decomposition (ΔH d), and time to maximum rate under isothermal conditions (TMR iso), which were necessary and useful to insure safe storage or transportation for self-reactive substances applied in the process industries.

Explosion evaluation and safety storage analyses of cumene hydroperoxide using various calorimeters

Plenty of thermal explosions and runaway reactions of cumene hydroperoxide (CHP) were described from 1981 to 2010 in Taiwan. Therefore, a thermal explosion accident of CHP in oxidation tower in 2010 in Taiwan was investigated because of piping breakage. In general, high concentration of CHP for thermal analysis using the calorimeter is dangerous. Therefore, a simulation method and a kinetic parameter were used to simulate thermal hazard of high concentrations of CHP only by the researcher. This study was applied to evaluate thermal hazard and to analyze storage parameters of 80 and 88 mass% CHP using three calorimeters for the oxidation tower, transportation, and 50-gallon drum. Differential scanning calorimetry (DSC) (a non-isothermal calorimeter), thermal activity monitor III (TAM III) (an isothermal calorimeter), and vent sizing package 2 (VSP2) (an adiabatic calorimeter) were employed to detect the exothermic behavior and runaway reaction model of 80 and 88 mass% CHP. Exothermic onset temperature (T0), heat of decomposition (ΔHd), maximum temperature (Tmax), time to maximum rate under isothermal condition (TMRiso) (as an emergency response time), maximum pressure (Pmax), maximum of self-heating rate ((dT/dt)max), maximum of pressure rise rate ((dP/dt)max), half-life time (t1/2), reaction order (n), activation energy (Ea), frequency factor (A), etc., of 80 and 88 mass% CHP were applied to prevent thermal explosion and runaway reaction accident and to calculate the critical temperature (Tc). Experimental results displayed that the n of 80 and 88 mass% CHP was determined to be 0.5 and the Ea of 80 and 88 mass% CHP were evaluated to be 132 and 134 kJ mol−1, respectively.

Thermal Hazard Evaluation of Lauroyl Peroxide Mixed with Nitric Acid

Many thermal runaway incidents have been caused by organic peroxides due to the peroxy group, –O–O–, which is essentially unstable and active. Lauroyl peroxide (LPO) is also sensitive to thermal sources and is incompatible with many materials, such as acids, bases, metals, and ions. From the thermal decomposition reaction of various concentrations of nitric acid (HNO3) (from lower to higher concentrations) with LPO, experimental data were obtained as to its exothermic onset temperature (T0), heat of decomposition (ΔHd), isothermal time to maximum rate (TMRiso), and other safety parameters exclusively for loss prevention of runaway reactions and thermal explosions. As a novel finding, LPO mixed with HNO3 can produce the detonation product of 1-nitrododecane. We used differential scanning calorimetry (DSC), thermal activity monitor III (TAM III), and gas chromatography/mass spectrometer (GC/MS) analyses of the reactivity for LPO and itself mixed with HNO3 to corroborate the decomposition reactions and reaction mechanisms in these investigations.

Isothermal versus non-isothermal calorimetric technique to evaluate thermokinetic parameters and thermal hazard of tert-butyl peroxy-2-ethyl hexanoate

Liquid organic peroxides have been broadly employed in the process industries such as tert-butyl peroxy-2-ethyl hexanoate (TBPO). This study investigated the thermokinetic parameters of TBPO, a typical liquid organic peroxide, by isothermal kinetic algorithms and non-isothermal kinetic algorithms with thermal activity monitor III, and differential scanning calorimetry, respectively. An attempt has been made to determine the thermokinetic parameters by simulation software, such as exothermic onset temperature (T0), maximum temperature (Tmax), decomposition (∆Hd), activation energy (Ea), self-accelerating decomposition temperature, and isothermal time to maximum rate (TMRiso). A liquid thermal explosion model was established for a reactor containing liquid organic peroxide of interest. From experimental results, liquid organic peroxides’ optimal conditions for avoiding a violent runaway reaction of storage and transportation were created.

Comparative study on the effects of two antifungal drugs against Candida albicans by microcalorimetry and transmission electron microscopy

In this work, a multi-channel thermal activity monitor (TAM 2277) was applied to study the growth metabolism of Candida albicans (C. albicans) in vitro in the absence and presence of different concentrations of ketoconazole (KTZ) and itraconazole (ITZ). The results showed that the half inhibiting concentrations (IC50) of C. albicans by KTZ and ITZ are 73.5 and 66.3 μmol L−1, respectively. So the antibiotic effect of ITZ was slightly better than that of KTZ. The morphology of C. albicans cells both in the absence and presence of antifungal agents was examined by transmission electron microscopy (TEM). Our research also suggests that microcalorimetry is a fast, simple, non-invasive, non-destructive and more sensitive method, and can be easily performed to study the antibiotic property of different species of drugs on microorganism compared to other biological and clinical methods.

Evaluation of thermal hazard for lauroyl peroxide by VSP2 and TAM III

When above certain temperature limits, lauroyl peroxide is an unstable material. If the thermal source cannot be properly governed during any stage in the preparation, manufacturing process, storage or transport, runaway reactions may inevitably be induced immediately. In this study, the influence of runaway reactions on its basic thermal characteristic was assessed by evaluating thermokinetic parameters, such as activation energy (Ea) and frequency factor (A) by thermal activity monitor III (TAM III). This was achieved under five isothermal conditions of 50, 60, 70, 80, and 90 °C. Vent sizing package 2 (VSP2) was employed to determine the maximum pressure (Pmax), maximum temperature (Tmax), maximum self-heating rate ((dT dt−1)max), maximum pressure rise rate ((dP dt−1)max), and isothermal time to maximum rate ((TMR)iso) under the worst case. Results of this study will be provided to relevant plants for adopting best practices in emergency response or accident control.

Microcalorimetric Study of Extruded Dog Food Containing Probiotic Micro-Organisms

Extruded dry dog food products claimed to have a probiotic ingredient of Enterococcus faecium (NCIMB10415) in the commercial available formulations under the brand name of ProBiotic LIVE (Bacterfield S.A., Luxembourg) were studied in the present work using a multichannel thermal activity monitor TAM III. Maximum specific growth rate, heat produced during different growth phases, and lag-phase duration were determined. The length of the lag-phase that can be used to determine the time necessary for the probiotic ingredient to restore its activity after consumption of probiotic containing extruded products was also measured. The calorimetric data confirmed the ability of the Enterococcus faecium to grow at the acidic pH conditions, modeling conditions of gastro-intestinal tract of dogs, and preserve its metabolic activity (viability) at the same level as at the neutral pH. The results obtained indicated that microcalorimetry was a precise and convenient tool for monitoring probiotic activity in complicated solid-state matrices.

RSTVOLC implementation on MODIS data for monitoring of thermal volcanic activity

An optimized configuration of the Robust Satellite Technique (RST) approach was developed within the framework of the ‘LAVA’ project. This project is funded by the Italian Department of Civil Protection and the Italian Istituto Nazionale di Geofisica e Vulcanologia, with the aim to improve the effectiveness of satellite monitoring of thermal volcanic activity. This improved RST configuration, named RSTVOLC, has recently been implemented in an automatic processing chain that was developed to detect hot-spots in near real-time for Italian volcanoes. This study presents the results obtained for the Mount Etna eruption of July 14-24, 2006, using the Moderate Resolution Imaging Spectroradiometer (MODIS) data. To better assess the operational performance, the RSTVOLC results are also discussed in comparison with those obtained by MODVOLC, a well-established, MODIS-based algorithm for hot-spot detection that is used worldwide.

Preparation and Biological Effect of Nucleotide-Capped CdSe/ZnS Quantum Dots on Tetrahymena thermophila

In this paper, we described the preparation and characterization of different types of modified CdSe/ZnS quantum dots (QDs) and explored the biological effects of QDs with different surface modifications on the whole growth of unicellular protozoan Tetrahymena thermophila BF(5) using a thermal activity monitor air isothermal microcalorimeter. Our results demonstrated that adenosine 5'-monophosphate (AMP) showed stronger interaction with QDs than other types of nucleotide. AMP-QDs could stimulate the growth of T. thermophila while mercaptoacetic acid-capped CdSe/ZnS quantum dots inhibited it. In addition, the population density determination and fluorescence imaging of T. thermophila BF(5) also confirmed the results obtained from microcalorimetry. It is believed that this approach will provide a more convenient methodology for the kinetics and thermodynamics of microorganism when coexisting with QDs in real time, and all of which are very significant to understanding the effect of QDs to organism.

Green technology for improving process manufacturing design and storage management of organic peroxide

This study focused on green technology to replace the easy-to-make-mistake methods of predicting kinetics and the consumption energy of the transitional self-accelerating decomposition temperature (SADT) tests, using simply thermal analysis combined with kinetic and thermal hazard simulation. Organic peroxides (OPs) have been widely employed in the chemical industry as a polymerization initiator, cross-linking or hardening agent. We investigated the thermokinetic parameters of tert-butyl peroxy-2-ethyl hexanoate (TBPO) with various calorimetric tests by differential scanning calorimetry (DSC) and thermal activity monitor III (TAM III). Comparisons of two calorimetric tests were conducted for simulation approach, which can predict the beneficial kinetics of thermal decomposition, and then we determined the thermal hazard of TBPO. Therefore, this study used green technology to predict the safety parameters of organic peroxide, which also can be applied to optimize reactor design, to improve feeding safety, and to correct process mistakes for other chemicals.

Comparison of the Isothermal and Non-Isothermal Kinetics for Predicting the Thermal Hazard of Tert-Butyl Peroxybenzoate

Tert-butyl peroxybenzoate (TBPB), a liquid organic peroxide, has been widely employed in the petrifaction industry as a polymerization formation agent. This study investigated the thermokinetic parameters of TBPB by isothermal kinetic algorithms and non-isothermal kinetic equations, using thermal activity monitor III (TAM III) and differential scanning calorimetry (DSC), respectively. Simulations of 0.5 L, 25 kg, 55 gallon, and 400 kg reactors in liquid thermal explosion models were performed. It is based on the thermal hazard properties, such as the heat of decomposition (∆Hd), activation energy (Ea), self-accelerating decomposition temperature (SADT), control temperature (CT), emergency temperature (ET), and critical temperature (TCR). From the experimental results, the optimal conditions to avoid violent runaway reactions during the storage and transportation of TBPB were determined.

Microcalorimetric study of the growth of bacterial colonies of Lactococcus lactis IL1403 in agar gels

Growth of Lactococcus lactis IL1403 in solid agar gels and liquid cultures at different glucose concentrations of 2, 10 and 20 g/L and different inoculation rates from 10 0 to 10 6 cfu/mL with the 10-fold increment was studied using thermal activity monitor TAM III. In parallel to calorimetric measurements the changes of glucose and lactic acid concentrations and pH of culture media were measured in order to obtain additional information for the interpretation of calorimetric power–time curves. Maximal specific growth rates of heat evolution proportional to growth rates of biomass μ max (W/h), heat produced during different growth stages Q TOT (J/mL), Q ExP (J/mL) and duration of lag-phases λ (h) were obtained by processing calorimetric curves. The sizes of colonies were measured also at the end of growth using microscope. The data obtained together with calculated heat yield coefficient Y Q (J/cfu) allowed to analyze and describe quantitatively the growth of individual colonies and develop a model of multistage growth of a typical colony of L. lactis in 1% agar gel. Microcalorimetry used in combination with other relevant methods is a very powerful and precise tool in studying solid-state fermentations.

Prediction of incompatible reaction of dibenzoyl peroxide by isothermal calorimetry analysis and green thermal analysis technology

Dibenzoyl peroxide (BPO) has been widely employed in the petrifaction industry. This study determined the unsafe characteristics of organic peroxide mixed with incompatible materials so as to help prevent runaway reactions, fires or explosions in the process environment. Thermal activity monitor III (TAM III) was applied to assess the kinetic parameters, such as kinetic model, reaction order, heat of reaction (ΔHd), activation energy (Ea), and pre-exponential factor (k0), etc. Meanwhile, TAM III was used to analyze the thermokinetic parameters and safety indices of BPO and contaminated with sulfuric acid (H2SO4) and sodium hydroxide (NaOH). Simulations of a 0.5 L Dewar vessel and 25 kg commercial package in green thermal analysis technology were performed and compared to the thermal stability. From these, the optimal conditions were determined to avoid violent reactions in incompatible materials that cause runaway reactions in storage, transportation, and manufacturing.