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Plastics are known for their beneficial properties, such as lightness, strength, and low cost, and they are used in different applications such as construction, electronics, and packaging. However, plastics do not degrade naturally, accumulating in soils and affecting the environment. Recycling techniques have been developed to minimize plastic waste; chemical recycling through pyrolysis has been cataloged as an effective method for transforming plastic waste into high-value products in the chemical and petrochemical industry. Previous studies of feedstock degradation through thermogravimetry analysis (TGA) have been essential to estimate the optimal temperature ranges to evaluate the pyrolysis process. The present work aims to study regression models to estimate the temperature degradation of polystyrene (PS) through thermogravimetry data, which can be applied before the pyrolysis process. In addition, this work compares linear and polynomial regression models to estimate the best-fitting model and to determine the maximum temperature of degradation of PS by different heating rates. Relative errors were calculated by comparing them with experimental values from the literature not included in the models. As a result, a polynomial model of a fourth-order obtained a better fit with an r²=70.45 % compared to the linear models, where the best fit was obtained with r²= 69.71 %. However, a higher relative error was obtained, with the polynomial models being the lowest, 7.35 and 0.50 % for 15 and 60 °C min-1; for the linear models, 7.05 and 0.39 % were obtained for heating rates of 15 and 60 °C min-1, respectively. [ABSTRACT FROM AUTHOR]

The traditional biodiesel production process consumes a large amount of energy by maintaining a reaction mixture of oil and alcohol for extended periods of up to 120 min at average temperatures of 60 °C. To reduce biodiesel production costs, alternatives have emerged that reduce reaction time and consequently the production costs. One of these alternatives is hydrodynamic cavitation, which through the contribution of sensitive heat, because of the phase change, allows to provide a large amount of energy to the fluids in reaction. Some elements that cause low pressures, which allows the presence of cavitation, are orifice plates. This paper presents the results obtained from the production of biodiesel by hydrodynamic cavitation caused by an orifice plate. These results are compared with those obtained by the traditional method of stirring and heating. For both processes soybean oil was used as raw material, a molar ratio of methanol oil 6:1 and 12:1, sodium hydroxide as catalyst at 0.5 % w/w and a reaction temperature of 60 °C. The biodiesel obtained was characterized by the standard EN14214 which establishes a minimum of 96.5% of FAME. The results show that this minimum value is exceeded at 17 min with the orifice plate, while with the traditional method the time was 120 min, demonstrating that hydrodynamic cavitation reduces the time and energy cost in biodiesel production. [ABSTRACT FROM AUTHOR]