José María Vicaria

In recent years, several toxicological studies concerning pollutants have focused on the joint toxicological assessment of co-pollutants, revealing that multiple interactions between toxics can appear and need to be described

The growing use of ozone (O₃) in the last years to clean and enhance the physicochemical properties of starches, widely used as additives in food, beverage, and pharmaceutical industries, calls for a better understanding of their oxidation process. High pH, however, decomposes O₃ rapidly, forming highly-oxidant radicals, thus increasing the complexity of the reaction system. In this study, a kinetic model for the ozonation reaction of starch in an alkaline medium was developed and experimentally validated. Firstly, the concentration of hydroxyl radicals (^●OH) over the reaction time is evaluated through the degradation of pCBA (a probe compound) to later evaluate and model the oxidation process of starch based on Chemical Oxygen Demand (COD) measurements. By using a semi-batch reactor containing alkaline solutions at pH = 13, different O₃ concentrations (0–42.30 g/Nm³) and temperatures (20–60 °C), a pseudo first-order kinetic model was proposed to model the pCBA-ozone reaction. This model estimates the ^●OH formation, being [^●OH] constant and proportional to the O₃ continuous dose. Therefore, under the conditions studied, ^●OH is a non-limiting reactant independent of temperature. The activation energy was estimated at 14.2 ± 2.1 and 14.5 ± 0.6 KJ/mol for 21.15 and 42.30 gO₃/Nm³, respectively. Then, COD data were used to propose a kinetic model for ozone-starch oxidation in alkaline media, where besides O₃ concentration and temperature, starch concentration (600–1700 mg/L) was also varied. According to the results, higher temperatures and longer reaction times resulted in a greater COD reduction, being it more pronounced at lower initial starch concentration. The activation energy of the ozone radicals-starch reaction was estimated at 8.1 ± 0.4 KJ/mol, being significantly lower than those reported for the reaction between pCBA and ^●OH.

The statistical design of experiments has been used to assess the detergency of starch adhering to stainless steel considering three factors: pH, flow rate, and concentration of silica particles in the cleaning solution. The cleaning tests were carried out in a continuous‐flow device that simulates the behavior of a Cleaning‐In‐Place washing system. Different statistical designs were used to evaluate the detergency of cleaning solutions in the absence of surfactants and with two nonionic surfactants, i.e., an ethoxylated alcohol, and an alkylpolyglucoside (APG). Expressions were developed to simulate detergency levels as a function of the variables assayed, determining the optimal detergency of each cleaning solution studied. The results indicate that the variable most influential on detergency was pH. Cleaning solutions with high alkalinity are required to achieve a significant cleaning efficiency. On the other hand, the silica‐particle concentration did not influence the detergency results using cleaning solutions without surfactants. Nevertheless, the addition of either the ethoxylated alcohol or the APG to the cleaning solution with silica particles has a significant effect on detergency: it diminished with the ethoxylated alcohol and increased with the APG. Maximum detergency was found at the highest level of pH, particle concentration, and flow rate when the APG was added to the cleaning solution.