DEVELOPMENT OF SULFENTRAZONE EXTRACTION PROCEDURE FROM COMMERCIAL HERBICIDE FORMULATION AND DETERMINATION OF ITS IONIZATION CONSTANT (pKa) BY POTENTIOMETRIC TITRATION
Journal Title: Periódico Tchê Química - Year 2017, Vol 14, Issue 27
Abstract
The herbicide sulfentrazone (SFZ) is widely used in soybean and sugarcane crops, although it is classified as very dangerous to the environment. To minimize barriers to the development of research with this herbicide due to the high cost of acquisition of its analytical standard and the availability of few distributors to acquire the standard in the country, a procedure of extraction and purification of SFZ was developed from a commercial herbicide formulation available in Brazil. Using the most suitable experimental conditions established for the extraction procedure, the SFZ content in the resulting solid after extraction and drying was 97.5% (m/m), which value was determined by acid-base potentiometric titrations. To characterize the solid obtained in this procedure, the material was studied by thermal analysis (thermogravimetry and differential scanning calorimetry) and Fourier transform infrared photoacoustic spectroscopy (FTIR-PAS) to confirm the presence of functional groups present in the SFZ molecule. Thermal analysis of the solid resulting from the extraction indicated processes of melting, thermal degradation and volatilization of the SFZ during its heating. By potentiometric titrations of the purified solid dissolved in water/acetonitrile (ACN) binary mixtures, it was possible to determine the ionization constant (pKa) of SFZ in water at 25.0ºC. By this study, extrapolated value of pKa in water is 6.45 obtained from the linear correlation of pKa versus molar ACN fraction plot. The value obtained at 25.0 °C by potentiometry in this study is quite close to the literature value of 6.56 determined at 20 °C by the spectrophotometric technique. However, the pKa value determined by potentiometric titrations of dilute solutions of the SFZ commercial formulations was much higher than that of 6.56, indicating that the degree of ionization of SFZ under herbicide application conditions can be quite distinct in the presence of possible adjuvants present in the commercial formulation of the herbicide.
Authors and Affiliations
Antonio Rogério FIORUCCI
Keywords
Related Articles
- EP ID EP252221
- DOI -
- Views 186
- Downloads 0
OPTIMIZATION OF THE WICK THICKNESS IN A FLAT PLATE HEAT PIPE WITH MULTIPLE HEAT SOURCES
Based on the simplified two-dimensional heat and hydrodynamics models we estimate an optimal thickness of the wick layer that should be sintered inside the flat plate heat pipe to provide its maximum operating performanc...
SPATIAL EVALUATION OF THE WATER QUALITY FROM THE VELHAS RIVER CHANNEL, IN THE STATE OF MINAS GERAIS
This study presents an evaluation of the water quality variability of 19 monitoring stations located in the channel of the Velhas river, using multivariate statistical techniques - Cluster Analysis (CA) and Principal Com...
PREPARATION OF CATALYST SUPPORT FROM BIO CARBON
The overuse of non-renewables resources in the last decades has generated negative consequences for the society, which have boosting the search for mitigating the damage caused in the environment. Aiming to contribute...
COMPARISION OF PURE MEMBRANES OF 13X AND 5A ZEOLITE FOR REMOVAL OF ACRIDINE ORANGE DYE FROM AQUEOUS SOLUTIONS
This work has been performed to test pure membranes of two zeolites as effective adsorbents for the removal of the cationic dye acridine orange (AO) from aqueous solution. The membranes were made through fast and easy me...
IDEAS OF STUDENTS ON THE ATOMISTIC NATURE OF MATTER
The alternative concepts movement that emerged in the 1970s continues to be highly relevant in the teaching of sciences, particularly chemistry, given that it can be the starting point for teachers to revisit their pedag...