Friedman Method Research Articles

Kinetic and thermodynamic studies of phase transition from hexagonal to discotic liquid crystal in metal-free 1,4,8,11,15,18,22,25-octahexylphthalocyanine

ABSTRACT The objective of this work is to examine the Phase changes in the metal-free 1,4,8,11,15,18,22,25-octahexylphthalocyanine compound under non-isothermal and predicted isothermal conditions by Differential Scanning Calorimetry (DSC) and Scanning Electron Microscopy (SEM). The kinetic and thermodynamic parameters of the two endothermic phases observed were reported. The reaction of these two changes appeared to be the transition from hexagonal columnar mesophase to a less ordered crystalline phase and then to the transition to the discotic columnar mesophase. The isoconversional models, namely, Friedman and Flynn-Wall-Ozawa (FWO) were employed to calculate the effective activation energy and pre-exponential factor. The reaction model involved in the phase change was proposed by employing the z-master plot for nonisothermal results and the integral form for isothermal results. Additionally, by using the activation energy obtained from Friedman and FWO methods the thermodynamic parameters, including the changes of enthalpy, the Gibbs free energy and entropy were determined. The change of enthalpy showed a quite consistent tendency with the activation energy, whereas the change of Gibbs free energy always kept positive during the whole process, this implies that the reaction is non-spontaneous and thus requires external heat supply.

Discernment of synergy during the co‐pyrolysis of lipid‐extracted microalgae and digested municipal solid waste: a thermogravimetric–mass spectrometric study

AbstractBACKGROUNDThe current study investigated the co‐pyrolysis nature of biomasses, gas yields, kinetics and thermodynamics of Chroococcus sp. (CC), digested municipal solid waste (DMSW) and their mixtures using thermogravimetric analysis and mass spectrometry.RESULTSThermogravimetric/differential thermogravimetric analysis indicated three major weight loss stages: dehydration (50–150 °C), thermal degradation of structural components (150–550 °C) and char decomposition (550–800 °C). The gases released during the process mainly contained CO, CH4, CO2 and H2 as main components. Also, with an increase in the composition of CC, the hydrogen yields were noticed to increase. Model‐free isoconversional methods, the Kissinger–Akahira–Sunose and Friedman methods, were considered to identify the activation energy. The kinetic results showed that an increase in the percentage of CC in the mixture lowered the activation energy. The activation energies recorded for CC, DMSW, CD‐1, ‐2 and ‐3 were 282.11, 202.55, 210.54, 145.46 and 139.98 kJ mol−1, respectively.CONCLUSIONSThermodynamic and kinetic analysis for CC, DMSW and their mixtures can be effectively used for reactor design and process optimization for similar types of waste materials. © 2021 Society of Chemical Industry (SCI).

Kinetic study of heating pinewood sawdust with different methods using thermogravimetric analysis

A kinetic study based on pinewood (Pinus montezumae) was carried out at heating rates of 5, 10, 15, and 20 °C min−1. The Flynn–Wall–Ozawa (FWO), Kissinger–Akahira–Sunose (KAS), and Friedman methods were used to analyze the thermal behavior of samples. Thermogravimetry (TG) and derivative thermogravimetry (DTG) curves were obtained at non-isothermal conditions. Ultimate and proximate analyzes from pinewood were obtained and the greater decomposition was in the range of 250 to 380 °C. Mean values of activation energy (Ea) and frequency factor (A) by FWO method were 192.4 kJ mol−1 and 2.73 × 1014 min−1, respectively, whereas the aforementioned values by KAS method were 181.8 kJ mol−1 and 3.32 × 1013 min−1. Lower value of mean activation energy (174.1 kJ mol−1) was obtained with Friedman method.

A simplified kinetic model based on a universal description for solid fuels pyrolysis: Theoretical derivation, experimental validation, and application demonstration

A kinetic model for the prediction of the conversion rate is crucial for research and development of biomass pyrolysis. The complexity of the existing kinetic studies and the diversity in pyrolysis kinetic data largely compromise the application of kinetic models. For the purpose of developing a generalized kinetic model, in this paper, we derive a universal description for all the common reaction mechanisms of solid fuels pyrolysis, among which the first-order reactions can be described as standardized general extreme value distribution. Based on the universal description, a simplified kinetic model with only one kinetic parameter is proposed. Then, we perform an experimental study of cellulose and poplar wood pyrolysis in order to validate the new model and to demonstrate its usefulness. The prediction results of the new model are very consistent with those from the conventional Arrhenius model and also agree well with the experimental data. Afterwards, the new model is applied to evaluate the kinetics for poplar wood pyrolysis, and comparisons between our model results and the commonly used Friedman method in terms of accuracy and applicability are shown. The new model also illustrates that the activation energies vary remarkably with the conversion degree and heating rate.

Research on Thermal Decomposition Kinetics and Thermal Safety for a New Epoxiconazole Crystal.

To clarify the thermal safety inherent in a new epoxiconazole crystal, differential scanning calorimetry (DSC) and adiabatic accelerating rate calorimetry (ARC) were used for testing and research. The Friedman method and model method were used to analyze thermal decomposition kinetics based on the DSC data, and the N-order and autocatalytic decomposition reaction kinetic models were established. The double scan method was utilized to verify the autocatalytic effect during the decomposition process. The Friedman method, N-order, and autocatalytic model methods were used to study the substance’s thermal decomposition characteristics. ARC data are utilized to verify the aforementioned prediction results and the kinetic parameters that were obtained based on ARC data from N-order and autocatalytic model methods that concur with the simulation results. This paper applies the N-order and autocatalytic model to the kinetic model to further predict thermal safety parameter time to maximum rate under adiabatic conditions.

Thermal and electrochemical impact of kaolin on a direct carbon fuel cell

This paper investigates the impact of kaolin, a dominant coal mineral, on the thermal and electrochemical behaviour of the molten ternary carbonate eutectic ((Li,Na,K)2CO3) in the direct carbon fuel cell (DCFC) as a means to simulate long-term operation with a continuous coal feed. Thermogravimetric and differential thermal analysis, coupled with kinetic modelling using the Friedman method, shows a substantial decrease in activation energy for eutectic melting with the addition of kaolin. Electro-oxidation of carbon (graphite) is also enhanced with kaolin in the electrolyte, increasing from 17.68 mA/cm2 at 0 wt% kaolin to the highest value of 162 mA/cm2 with 15 wt% kaolin added. It is shown that the improvement is due to increasing oxide concentration resulting from kaolin dissolution in the electrolyte.

Kinetic analysis of the spontaneous thermal polymerization of acrylic acid

Acrylic acid is a monomer that has been responsible for a number of severe explosions worldwide as a result of thermal runaway. The present work was intended to lead to an improved understanding of the kinetics of the thermal polymerization and Michael addition reaction (MAR) of acrylic acid. Sealed cell differential scanning calorimetry was carried out, and the kinetics of the thermal polymerization of acrylic acid were assessed on the basis of the model-free Friedman method. In addition, microcalorimetry using a Thermal Activity Monitor IV apparatus was conducted to determine the kinetic parameters for the MAR. The rate constant for the MAR was found to be k (s−1) = 3.45 × 105 × exp (− 9.48 × 103/T (K)), while the activation energy was 78.8 kJ mol−1. The progress of the MAR was fitted with an n-order reaction model, and the reaction order as well as the rate constant was determined to be linearly proportional to temperature. By employing a modified n-order reaction model in which the reaction order was a linear function of temperature, we obtained a reaction rate equation for the MAR that closely reproduced the experimental results over a wide temperature range.

Kinetic modeling and analysis of pyrolysis of polymethyl methacrylate using isoconversional methods

Pyrolysis the waste plastic into fuel is a promising way to protect the environment. In this study, we study the thermal decomposition processes of polymer Poly (methyl methacrylate) PMMA. This work used the microscale combustion calorimeter (MCC) as a tool to study the degradation. MCC is an applicable method to calculate the material combustion parameters by using milligram samples. The experiments were carried out at four heating rates 0.25, 0.5, 0.75, and 1 K/s. The temperature range in which the pyrolysis reaction occurs is « 300-470 oC. We applied several isoconversional methods such as Friedman, Ozawa, Flynn-Wall-Ozawa (FWO), and Kissinger-Akahira-Sunose (KAS) to estimate the apparent activation energy of thermal degradation of Poly(methyl methacrylate). Determine the activation energy from each method evaluated against the experimental data. With investigation, the FWO method shown much higher values for activation energy for PMMA polymer more than the other two methods, and the average value much higher than the Friedman and KAS methods. On the other hand, as a differential method, Friedman showed more accurate results Ea=216.65kJ/mol, and KAS method 228.61 kJ/mol. Our investigation may give a few experiences to how to more readily portray trial results with hypothetical expectations and essential data for calculating the activation energy of potential pyrolysis reactors.

Thermogravimetric Study of Refuse Derived Fuel Produced from Municipal Solid Waste of Kazakhstan

Efficient waste management, including proper utilization of municipal solid waste (MSW), is imperative for a sustainable future. Among several management options, pyrolysis and combustion of MSW has regained interest because of improved combustion techniques. This work aims to investigate the thermal conversion and combustion characteristics of refuse derived solid fuel (RDF) samples and its individual compounds collected from Nur-Sultan’s MSW landfills. The waste-derived solid RDF samples originally consist of textile, mixed paper, and mixed plastic. In particular, the samples, including RDF and its three constituent components, were analyzed in the temperature range of 25 to 900 °C, at three different heating rates, by thermogravimetric method. The gross calorific value for RDF derived from Nur-Sultan’s MSW was determined to be 23.4 MJ/kg. The weight loss rates of the samples, differential thermogravimetry (DTG), and kinetic analysis were compared between individual RDF components and for the mixed RDF. Combustion kinetics models were calculated using Flynn–Wall–Ozawa (FWO), Kissinger–Akahira–Sunose (KAS), and Friedman methods. The results revealed that first decomposition of RDF samples was observed at the range of 180–370 °C. Moreover, the activation energy for conversion of RDF was observed to be the highest among the constituent components and gradually decreased from 370 to 140 kJ/kmol.

Kinetics and Mechanism of Thermal and Catalytic Decomposition of Hydroxylammonium Nitrate (HAN) Monopropellant

AbstractHydroxylammonium nitrate (HAN) monopropellant with its low sensitivity, volatility and toxicity, not only promises a safer substitute to hydrazine but also offers a higher specific impulse and a positive oxygen balance. This study primarily explores the decomposition mechanism and underlying kinetics for a newly developed cerium oxide‐based catalyst. The chemical kinetics involved in the thermal and catalytic decomposition was examined through an isoconversional method using thermogravimetric analysis (TG) data. The activation energy (Ea) was evaluated using differential isoconversional method (Friedman's method) and advanced integral isoconversional method (Popescu‐Ortega's method). To find frequency factor, compensation effect method (ACE) and intercept method (A0) were used. Advanced integral method could not provide realistic kinetic parameters while differential method predicted values similar to reported values for thermal decomposition. The values obtained for thermal decomposition were found matching with reported values obtained by other techniques which validated the methodology adopted. The reaction mechanism for both thermal and catalytic decomposition were proposed based on evolved gas analysis. The mechanism proposed was able to describe the variable kinetic parameters extracted from isoconversional method. Overall Ea of thermal decomposition of HAN was ∼95 kJ/mol. The decomposition over ceria‐based catalyst was distributed over three stages namely inception, peak and decay with Ea of ∼33 kJ/mol, ∼170 kJ/mol and ∼130 kJ/mol, respectively. Under identical conditions, iridium‐based catalyst show two decomposition stages with Ea of ∼65 kJ/mol and ∼120 kJ/mol while final stage being evaporation of HNO3. The ceria catalyst favoured N2 formation, increased decomposition of HNO3 and enhanced decomposition enthalpy.

COMPARATIVE STUDY OF VARIOUS APPROACHES IN ANALYSIS OF TGA DATA OF DEVOLATILIZATION OF HIGH ASH INDIAN COAL

ABSTRACT Thermo gravimetric analysis (TGA) has been regularly employed for the estimation of devolatilization rates and measurement of char reactivity of coal. In general, TGA studies may be classified as isothermal or non-isothermal. In the first case temperature of the sample is kept constant whereas in case of latter the rate of temperature increase is kept constant. The current research work deals with the non-isothermal TGA study and kinetic analysis of three typical pulverized high-ash Indian coal samples each weighing around 15 mg. TGA experiments were carried out for four different heating rates (5, 10, 15, 20 K/min) and weight loss curves have been obtained. Out of the various methods proposed to analyze the TGA data, the following methods have been evaluated i) Friedman method, ii) Flynn-Wall-Ozawa method (FWO), iii) Kissinger method, iv) Kissinger-Akahira-Sunose (KAS) method, and v) Miura-Maki method. Activation energy and frequency factor to be used in the Arrhenius equation is calculated using all the above methods. The most accurate method for analyzing TGA data for high-ash Indian coal is FWO as per studies carried out in this research work.

Kinetic evaluation of tobacco stalk waste exposed to alkaline surface treatment under different conditions

Lignocellulosic materials (some natural fibers) have relevant mechanical properties when incorporated in polymeric matrices, being a renewable source to replace synthetic fibers; however, for good adhesion and durability, it is necessary to modify the fibrous surface structure in order to eliminate unwanted compounds. This work aims to evaluate different conditions of alkaline treatment of tobacco stalk waste using 10 and 15 wt% sodium hydroxide (NaOH) during an exposure time of 3 or 5 h. Thermal, chemical, and morphological characterizations as well as kinetic analysis were performed. Through Fourier transform infrared spectroscopy, it was possible to identify the partial removal of compounds such as lignin, hemicellulose, and extractives, increasing the thermal stability, which was proven by thermogravimetric analysis. Furthermore, X-ray diffraction shows a higher crystallinity index from cellulose after the alkaline treatment. Through the kinetic analysis, it is possible to observe that both methods presented similar activation energy values (Ea). In addition, after the alkaline treatment there was a reduction in Ea, the most evident result being observed in the TSW\10\5 sample, which presented an average value of Ea of 223.95 ± 15.79 kJ/mol by the Flynn–Wall–Ozawa method and 218.74 ± 24.69 kJ/mol by the Friedman method. Scanning electron microscopy showed the exposure of the microfibrils and an enhancement of roughness after alkaline treatment. Tobacco stalk wastes has potential application as reinforcing filler in composite materials since surface alkaline modification provides higher fiber/matrix adhesion through the removal of amorphous compounds.

Isothermal Kinetics of Epoxyphosphazene Cure

The influence of epoxycyclophosphazene modifier on the process of epoxy-amine curing was studied by differential scanning calorimetry (DSC). The study revealed that the curing process of epoxyphosphazene binders with 4′4′diaminodiphenylsulfone (DDS) provides more complete curing of the formulations in comparison with ones applying low molecular-weight polyamide curing agent (L-20). The isothermal kinetics of curing was described by means of model fitting and the isoconversional approach (Friedman method). Accurate n-order approximation was obtained for all systems under study. In particular, the 2-order equation fits well with the main part of curing excluding high degrees of conversion. The process of curing could be distinguished into three zones. The transition from zone 2 to zone 3 correlates with gelation. According to the isoconversional analysis by Friedman method, the diffusion-controlled mechanism is found at final stage of curing.

Pyrolysis kinetics and thermodynamic parameters of plastic grocery bag based on thermogravimetric data using iso-conversional methods

The enormous growth in the consumption of plastic grocery bags and their non-biodegradability nature has become a serious cause of waste generation. In the context of the disposal of plastic, pyrolysis is a promising technique that addresses the energy crisis issue too. Therefore, in this work, pyrolysis kinetics and thermodynamic parameters of plastic grocery bags were investigated using different iso-conversional methods (Starink, Kissinger–Akahira–Sunose, Ozawa–Wall–Flynn, and Friedman methods) based on thermogravimetric analysis data at multiple heating rates (10, 20, 30, and 40 K/min). The pyrolysis of plastic grocery bags followed a single-step degradation process. The average activation energy values were found to be 133.21, 133.80, 139.12, and 192.08 kJ/mol from Starink, Kissinger–Akahira–Sunose, Ozawa–Wall–Flynn, and Friedman methods, respectively. The average values of the pre-exponential factor (using Kissinger’s equation) varied in between 7.14 × 108 and 1.47 × 1013 min−1. From the generalized master plot, it has been observed that the one-dimensional diffusion model is the most suitable one to describe the pyrolysis process. The trends of the thermodynamic parameters reveal the ease of reaction of the plastic grocery bag, as well as it is approaching the thermodynamic equilibrium state during the pyrolysis process. This investigation on the pyrolysis kinetics and thermodynamic parameters would be a reference in designing and scaling the reactor for the treatment of plastic grocery bags.

Isoconversional analysis of kinetic pyrolysis of virgin polystyrene and its two real-world packaging wastes

In present work, two polystyrene packaging wastes of expanded polystyrene (EPS) foam and Yakult polystyrene milk bottle (YPS) along with pure polystyrene (PS) have been subjected to high-temperature nitrogen pyrolysis experiments under four heating rates of 5, 10, 15 and 20 K min−1. A comparison among these samples in terms of pyrolysis features and specific decomposition temperatures has been made, and EPS tends to be the most readily to undergo pyrolysis while YPS appears to be the most thermally stable. Based on thermogravimetric data, kinetic analysis has been systematically performed using various isoconversional methods. The calculations show that the activation energies calculated over the whole pyrolysis range are slightly different among the six temperature-integral methods, but the temperature-differential Friedman method has given rather distinct activation energies. The activation energies over the whole pyrolysis process are mass conversion-dependent for three samples and the activation energy averaged is the highest for YPS, followed by pure EPS and then EPS. A method combining master-plots method and differential composite method has been attempted to search the most suitable reaction models and chemical reaction order-based F0.58, F0.61 and F1.14 are found to be the most suitable reaction models for describing pyrolysis of PS, EPS and YPS, respectively. With the Coats–Redfern method, the mass-conversion curves along with its differential curves have been simulated, yielding very satisfactory performances for three polystyrene samples. In addition, thermodynamic functions such as the changes of entropy, enthalpy and Gibbs free energy during waste pyrolysis processes are also considered.

Physico-chemical and thermal studies of newly developed phenolic copolymer resin and its antibacterial activities

A new random copolymer derived from 8-hydroxyquinoline, vanillin, 4-hydroxyacetophenone and formaldehyde was synthesized using conventional condensation polymerization. This copolymer further characterized by FT-IR, 1H NMR, 13C NMR, 13C NMR-DEPT, GPC, BET, DSC and TG-DTG. The apparent activation energy of resin by using Friedman methods and Kissinger-Akahira-Sunose (KAS) were 19.8 and 16.3 kJ mol−1, respectively. The three-dimensional diffusion (D3) decomposition mechanisms for the solid state thermal decomposition of copolymer have been observed from the Craido method and master plots. The copolymer resin could be used in the prevention of infections linked to medical devices.

Ring-opening polymerization of ε-caprolactone initiated by tin(II) octoate/n-hexanol: DSC isoconversional kinetics analysis and polymer synthesis

ABSTRACT The kinetics of ring-opening polymerization (ROP) of ε-caprolactone (ε-CL) initiated by 1.0, 1.5 and 2.0 mol% of stannous(II) octoate/n-hexanol (Sn(Oct)2/n-HexOH) wase successfully studied by non-isothermal differential scanning calorimetry (DSC) at heating rates of 5, 10, 15 and 20 °C/min. The DSC polymerization kinetic parameters of ε-CL were calculated using differential (Friedman) and integral isoconversional methods (Kissinger-Akahira-Sunose, KAS). The average activation energy (Ea ) values obtained from Friedman and KAS methods were in the range of 64.9–70.5 kJ/mol and 64.9–80.4 kJ/mol, respectively. The values of frequency factor (A) were determined from model fitting method using Avrami-Erofeev reaction model. The average values of A for the ROP of ε-CL initiated by 1.0, 1.5 and 2.0 mol% of Sn(Oct)2/n-HexOH (1:2) were 7.3x107, 2.8x106 and 1.2x106 min−1, respectively. From kinetics studied, the polymerization rate of ε-CL increased with increasing initiator concentration. The performance of Sn(Oct)2/n-HexOH in the synthesis of poly(ε-caprolactone) (PCL) was investigated by bulk polymerization at temperatures of 140, 160 and 180 °C. Sn(Oct)2/n-HexOH (1:2) could produce high number average molecular weight (= 9.0 × 104 g/mol) and %yield (89%) of PCL in a short period of time at Sn(Oct)2 concentration of 0.1 mol% and temperature of 160°C. The mechanism of the ROP of ε-CL with Sn(Oct)2/n-HexOH was proposed through the coordination-insertion mechanism.

Determination of SADT and TMRad of 3-bromo-1-(3,5-dichloropyridin-2-yl)-4,5-dihydro-1H-pyrazole-5-carboxylic acid: Applying thermal decomposition kinetics

The aim of this study was the evaluation of the safety parameters: Time to Maximum Rate under adiabatic conditions (TMRad) and self-accelerating decomposition temperature (SADT) for 3-bromo-1-(3,5-dichloropyridin-2-yl)-4,5-dihydro-1H-pyrazole −5-carboxylic acid (BDPCA) using evaluated kinetic parameters. The required decomposition kinetics was determined from the results of differential scanning calorimetry (DSC), microcalorimetry (C600), and adiabatic accelerating calorimeter (ARC). AKTS Thermokinetics (TK) and Thermal Safety (TS) Software were used for evaluation of the kinetic parameters of a decomposition reaction. The kinetic analysis was based on the isoconversional Friedman method. The values of TMRad amount to 110.2 °C, 107.3 °C, and 104.9 °C when calculated from the data collected by DSC, C600, and ARC, respectively. The simulated values of SADT for a 50 kg package of BDPCA amount to 101 °C and 96 °C when elaborating the DSC and C600 signals, respectively. Obtained results indicate that the application of kinetic parameters evaluated from the experiments carried out by three different calorimetric devices resulted in the evaluation of consistent safety parameters.

Thermodynamic model and kinetic compensation effect of oil sludge pyrolysis based on thermogravimetric analysis

Oil sludge is an organic solid waste in the petrochemical industry and improper treatment of oil sludge will cause environmental pollution. Pyrolysis is an effective way to realize its resource reuse. In order to understand the pyrolysis behavior and thermodynamic characteristics of oil sludge, four oil sludge samples from storage tanks were used as the research object, and pyrolysis experiments were carried out at heating rates of 5?, 10?, and 15? per minute under a nitrogen atmosphere. The kinetic parameters of pyrolysis of oil sludge are calculated by three equal conversion methods, Friedman method, Flynn-Wall-Ozawa method and Distributed activation energy model, and the most possible thermodynamic models for the main pyrolysis phase were analyzed and discussed by introducing the Malek method. The results show: high heating rate can promote the pyrolysis of oil sludge and in the pyrolysis stage, the apparent activation energy increases with the increase of the conversion rate. The apparent activation energy calculated by the Friedman method method is more reliable. The average apparent activation energies of the four oil sludge are 221.23, 84.71, 94.67, and 116.56 kJ/mol, respectively. The apparent activation energy and the pre-exponential factor are positively correlated, indicating that there is a kinetic compensation effect in the pyrolysis process. The thermodynamic models of the four oil sludge samples are all 3-D diffusion models, but their integral functions are different. The research results can provide theoretical support for the industrialization, harmlessness, and resource utilization of oil sludge pyrolysis.

A multivariate method of evaluating the effectiveness of optimizing the daily routine of schoolchildren

Annotation. The mode of a modern schoolboy-teenager is characterized by insufficient duration of night sleep, prolongation of homework, non-observance of diet, reduction of daily physical activity, excessive screen time, which under constant exposure can provoke a number of non-infectious and psychosomatic disorders. The purpose of the study is to evaluate the effectiveness of optimizing the daily routine of schoolchildren using the method of modeling structural equations. The study involved 175 students aged 10–14 years. Health status was assessed according to preventive medical examinations and screening-questionnaires with the calculation of the level of ill health and the coefficient of determination. Statistical data processing was performed using the licensed package SPSS Statistic v. 20 using one-way analysis of variance, correlation analysis, Chi-square test according to the Friedman method, Student’s t-test, as well as the method of modeling by structural equations (SEM) in the statistical package SEPATH Statistica. Using a normalized coefficient of determination, it was determined that for students in the experimental group were the most common signs of cardiorheumatological and allergic pathological conditions. Based on the pre-determined significance of the elements of the daily routine, the primary measures of primary prevention of pathological conditions were selected and implemented. The application of the multivariate SEM method using block data structures grouped by 11 variables (according to disease classes) and 15 blocks-elements of the daily routine allowed to evaluate the effectiveness of the prevention program. Pathology of the nervous (χ2=19.54; p<0.0001), respiratory (χ2=13.47; p=0.001) and cardiovascular systems (χ2=9.88; р=0.007) was determined to be the most “sensitive” to the impact of preventive measures. Thus, the proposed model allows to systematize the blocks that characterize both the prevention program and its effectiveness at different stages of implementation, which was determined by the level of morbidity of schoolchildren. The use of targeted preventive measures reduced the incidence rate by 10% in the experimental group against the background of an increase in pathological lesions in the control group by 22.9%.