Estudo de sistemas microemulsionados e nanoemulsionados contendo glicerina como retentores de umidade no solo

• Ano de defesa: 2016
• Autor(a) principal: Soares, Igor Andrey Aires
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Brasil; UFRN; PROGRAMA DE PÓS-GRADUAÇÃO EM CIÊNCIA E ENGENHARIA DE PETRÓLEO
• Palavras-chave em Português: Biodiesel; Glicerina; Microemulsão; Nanoemulsão; Umidade no solo; CNPQ::ENGENHARIAS::ENGENHARIA QUIMICA::TECNOLOGIA QUIMICA::PETROLEO E PETROQUIMICA
• Link de acesso: https://repositorio.ufrn.br/jspui/handle/123456789/23659

Environmental concerns and the demand for renewable sources of energy have driven the search for alternatives that may replace, at least partially, the use of fossil fuels. Among the viable options is the biodiesel, which has been produced on a large scale. However, with the increased use of biodiesel, scientists face a new challenge: finding alternatives to the use of Glycerin generated in the process. In light of this challenge, it is imperative to find new applications for this co-product. Water is another natural resource which availability that is becoming increasingly limited. Its proper use requires efficient strategies to avoid waste. Irrigation activities consume large amounts of water and it is responsible for a great percentage of its waste. Strategies related to water conservation in irrigation processes are imperative. This high consumption activity problem imposes the search for more efficient processes. In this context, this research proposes an increase in irrigation efficiency by using microemulsioned and nanoemulsioned systems. It also assesses the feasibility of using the abovementioned systems to retain moisture in the soil. The experiments were carried out in three stages. In step I, nanoemulsions were obtained from two microemulsioned systems. The first system (A) was composed of UNTL-90, coconut oil, and Glycerin + water 1:1. The second one (B) was composed of UNTL-90, pine oil, and Glycerin + water 1:1. For each system, a microemulsion point containing surfactant (15%), oil phase (2%), and polar phase (83%) was chosen. From these points, nine dilutions of each system were made to characterize and observe the application, always comparing the results against the original behaviors with water and microemulsions. The characterization of systems A and B obtained was performed through the following studies: visual aspect, droplet diameter, rheology, pH, and surface tension. In stage II, the moisture retention in the soil was checked using a traditional method, comparing the mass difference between dry soil, moist soil, and soil after drying in an oven. Soil samples were subjected to the application of micro and nanoemulsions, and dried in an oven at 50° C with evaluations after 24, 48, 72, 144 and 240 hours of drying. The assessment at 105° C was performed after 24 and 48 hours. At last, the evaluation of the soil dried in pots at room temperature had their moisture retention evaluated 5 and 8 days after application. Step III assessed system interference in the early plant development. At this stage, evaluations were performed on pre and post-emergence. Considering post-emergence when micro and nanoemulsions were applied only 10 days after the emergence of plants. The type of vegetable oil used influenced the characteristics of nanoemulsions obtained. For both systems, the droplet diameter varied based on the concentration of surfactant, with values between 14 and 31.8 nm to nanoemulsions A, and between 14.9 and 127.8 to nanoemulsions B. Nanoemulsions B are more viscous and exhibit a behavior closer to a Newtonian fluid when compared to the nanoemulsions A. As for pH, nanoemulsion A introduced values between 5.4 and 5.8 and nanoemulsions B had values between 3.8 and 4.5. The surface tension of the nanoemulsioned systems increased as a function of the concentration of the surfactant, with values between 41.6 and 47.7 dynam/cm for nanoemulsions A, and between 32 and 51.2 dynam/cm for nanoemulsions B. Nanoemulsioned let to soil moisture retention at all times and temperature conditions studied. The amount of moisture retained increased based on constituent concentration, with higher values (above 90%) for the original microemulsion, The germination of seeds was affected at 100% by nanoemulsions. However, nanoemulsions with lower concentrations of surfactant did not cause damage to the plants, being a viable alternative to promote moisture retention in the soil.