STUDY OF MICROEMULSION AND NANOEMULSION SYSTEMS CONTAINING GLYCERIN AS THE SOIL MOISTURE RETAINERS
Biodiesel, Glycerin, Micromulsion, Nanoemulsion, Moisture in the soil
Concern for the environment and the search for renewable energy sources have driven the search for alternatives that can replace, at least partially, fossil fuels. Among the environmentally viable options is biodiesel, which is being produced on a large scale, however, a disturbing front factor to the growth of production of this fuel is the fate of glycerin generated in the process, which makes it imperative to search for new applications for this coproduct . In addition to the sources of energy, other natural resource increasingly limited it is water. Their use requires increasingly rationality, especially in irrigation, activity that demands the highest throughput and where there are considerable losses and research needed to maximize the efficiency of its use for this purpose. In this context, an increase in the efficiency of irrigation can take place through the use of microemulsions and nanoemulsions systems. This work aims to use the glycerin in getting microemulsions and nanoemulsados systems and evaluate the feasibility of use of these in moisture retention in the soil. The research was conducted in three stages. In step I nanoemulsions were obtained from two microemulsions systems: system A, comprising UNTL-90, coconut oil and glycerin + water 1: 1, system B comprises UNTL-90, pine oil and glycerin + water 1: 1. For each system, we chose a microemulsion point containing 15% surfactant, 2% oil phase and 83% of the polar phase, these points were made nine dilutions of each system for characterization and application, when comparing the behavior with water and microemulsion source. The characterization of the A and B systems was accomplished through the following studies: visual appearance, diameter droplets, rheology, pH, and surface tension. In stage II, the moisture retention in the soil was verified by the traditional method, through the mass difference between dry soil, moist soil and after drying in an oven. Soil samples were subjected to the application of nanoemulsions and dried in an oven at different temperatures: (30 to 50°C) to 72 hours; at 50 ° C with evaluations after 24, 48, 72, 144 and 240 hours of drying; 105°C, measured after 24 and 48 hours and vessels, which were exposed at room temperature and had a moisture retention evaluated at 5 and 8 days after application. In Step III was verified the interference of nanoemulsions in the early development of plants, whose evaluations were performed in the pre-emergence and post-emergence, where the nanoemulsions were only applied 07 days after emergence. The type of vegetable oil used influences the characteristics of the obtained nanoemulsion. For both systems, the diameter of droplets varied depending on the surfactant concentration, with values between 14 and 31.8 nm for nanoemulsions A and between 14.9 and 127.8 for nanoemulsions B. Nanoemulsions B are more viscous and have closest behavior of a Newtonian fluid when compared to the nanoemulsions A. as to pH, the nanoemulsion shows values between 5.4 and 5.8, nanoemulsions B between 3.8 and 4.5. The surface tension of nanoemulsions systems increased due to the concentration of surfactant, with values between 41.6 and 47.7 dynes / cm for nanoemulsions A and between 32 and 51.2 dynes / cm for nanoemulsions B. For all conditions time and temperature studied, nanoemulsions provided moisture retention in the soil, and this increases with the concentration of constituents, with higher values for the microemulsion of origin, with retention percentage above 90%. Seed germination was 100% affected by nanoemulsions, however, nanoemulsions with lower concentrations did not cause damage to plants, which are a promising alternative for moisture retention in the soil in agriculture.