Aplicação de um secador híbrido para o estudo de liberação de rincoforol adsorvido em matriz carbonácea

Abstract

The coconut culture (Cocos nucifera L.) is highly developed in Brazil. However, this culture suffers from the attack of numerous pests, which cause irreparable damage to coconut trees. Among the main pests is the Rhynchophorus palmarum beetle, a transmitter of the Bursaphelenchus cocophilus nematode, responsible for the red-ring disease. This disease is considered one of the main causes of damage to fruit production and plant mortality. Currently, most insect control strategies in agricultural crops use pesticides. However, significant advances are associated with the use of semiochemicals, which relies on their release into the environment. Semiochemicals are substances that convey information during interactions between individuals. When these substances are specific for communication within the same species, they are called pheromones. The use of pheromones associated with food traps has proven to be quite efficient in capturing the pest insect. Due to environmental conditions, the volatilization kinetics of this substance may be impaired, resulting in excessive release rates, leading to high costs to the process, or too low, to the point of not being identified by insects. The pheromone used for capturing R. palmarum is called rincophorol and is available in plastic eppendorf containers. Studies aimed at reducing plastic consumption in pheromone handling are under development, where the application of the capture agent would be carried out in solid matrices, such as activated charcoal. In this context, this study aimed to evaluate the capacity of activated charcoal from the endocarp of oil palm as a solid matrix for incorporation and release of rincophorol. For this purpose, a complete 2³ experimental design was elaborated to investigate the influence of temperature (30°C and 40°C), air velocity (1.0 m/s and 2.0 m/s), and charcoal particle size (0.5 mm < Ø < 0.6 mm and 1.19 mm < Ø < 2.80 mm), evaluating the effective diffusivity of rincophorol as the response variable. In the experiments conducted, 0.1 g of activated charcoal saturated with rincophorol was used, which were inserted into polyethylene sachets, approximately 6.0 cm in length and 4.0 cm in height, previously perforated. The assays were carried out in a hybrid dryer, so that the dispensers were allocated on an internal support, maintaining a fixed distance from each other to avoid interference in the release of the semiochemical from each device. To better understand the phenomenon under study, the adsorbent was subjected to nitrogen adsorption and desorption analysis to determine the types of micropores predominant in the material. Based on the results of the design, it was possible to verify the effects of the main variables and two interactions, all of which were significant, revealing that the diffusivity of rincophorol varies linearly with changes in temperature and particle size, and it presents a higher value when employing a lower inlet air velocity. A mass transfer behavior analysis was also performed through mathematical drying models of Lewis and Page. It was found that the best condition was the use of rincophorol at a temperature of 30°C, with an air velocity of 1.0 m/s and particle size between 0.5 mm < Ø < 0.6 mm, a condition found in experiment number 1, which showed the lowest mass loss.