Potentiometric Titration of Vanadium (V) with Iron (II) in the Presence of NTA and DTPA Using Dry-Cell Graphite Electrode

A sensitive potentiometric titration for vanadium (V) based effect of ligands such as nitrilotriacetic acid (NTA) and diethylenetriaminepenta-acetic acid (DTPA) are reviewed. The potential iron system decreased the presence of NTA and DTPA. In this case, iron (III) increased with respect to the vanadium (IV) volume. The production of iron (III)-ligand complex has increased. This result suggested that the formation of V(V)-NTA and V(V)-DTPA complexes were less favoured than that of V(IV)-NTA and V(IV)-DTPA complexes. The calculated correlation coefficients (r) conveyed the effectiveness of the graphite electrode as the indicator electrode for the potentiometric titrations. On comparing the potential jump values, the extent of potential caused by DTPA was found to be more than that of NTA. The utilization of graphite electrode has facilitated the potentiometric titration by significantly causing larger potential jump. This method was precise and accurate as no interference of foreign ions was observed. Hence, the approach could be applied to the vanadium (V) of any samples.

Surface Charge governs the adsorption behaviour of glyphosate in Australian Oxisol Soil System

Glyphosate adsorption pattern is important for determining its environmental fate. Oxisol soil systems adsorb maximum glyphosate in the presence of biochar, however, the mechanism was not known. This article provides information concerning the role of surface charge in the case of Oxisol soil systems. Batch sorption experiments were conducted at the University of Sydney, Australia. Potentiometric titrations were done to calculate the surface charge in the case of Oxisol soil systems. Maximum adsorption of glyphosate in the Oxisol soil systems in the presence of char was due to an increase in net positive surface charge. This finding is of great importance to understanding the mechanism of herbicide soil interactions.

Surface Charge governs the adsorption behaviour of glyphosate in Australian Oxisol Soil System

Glyphosate adsorption pattern is important for determining its environmental fate. Oxisol soil systems adsorb maximum glyphosate in the presence of biochar, however, the mechanism was not known. This article provides information concerning the role of surface charge in the case of Oxisol soil systems. Batch sorption experiments were conducted at the University of Sydney, Australia. Potentiometric titrations were done to calculate the surface charge in the case of Oxisol soil systems. Maximum adsorption of glyphosate in the Oxisol soil systems in the presence of char was due to an increase in net positive surface charge. This finding is of great importance to understanding the mechanism of herbicide soil interactions.

Surface Charge governs the adsorption behaviour of glyphosate in Australian Oxisol Soil System

Glyphosate adsorption pattern is important for determining its environmental fate. Oxisol soil systems adsorb maximum glyphosate in the presence of biochar, however, the mechanism was not known. This article provides information concerning the role of surface charge in the case of Oxisol soil systems. Batch sorption experiments were conducted at the University of Sydney, Australia. Potentiometric titrations were done to calculate the surface charge in the case of Oxisol soil systems. Maximum adsorption of glyphosate in the Oxisol soil systems in the presence of char was due to an increase in net positive surface charge. This finding is of great importance to understanding the mechanism of herbicide soil interactions.

DEVELOPMENT OF SULFENTRAZONE EXTRACTION PROCEDURE FROM COMMERCIAL HERBICIDE FORMULATION AND DETERMINATION OF ITS IONIZATION CONSTANT (pKa) BY POTENTIOMETRIC TITRATION

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.

Turmeric Powder as a Natural Heavy Metal Chelating Agent: Surface Characterisation

The present study was conducted to investigate surface properties of turmeric in order to evaluateits detoxification potential and ability to sequester toxic metals ions. Scanning Electron Microscopy (SEM),Energy Dispersion Spectroscopy (EDS), Infra-Red (IR) spectroscopy and potentiometric titrations wereemployed for characterisation of the surface of turmeric powder. Spectroscopic studies revealed that thesurface of turmeric powder was porous mainly composed of polymeric -OH , -NH , -CH2 , -COO and-OH groups of polysaccharides. From potentiometric titrations and modelling of batch titration data, it wasfound that surface of the turmeric contains at least four binding sites with pKa values 3.56 (pK1), 4.83(pK2), 7.68 (pK3) and 10.4 (pK4). Turmeric powder contains highest concentration of amino and hydroxylgroups for the pK4 values i.e., 0.55 mmol/ g. The total binding sites concentration for turmeric powderwas 1.2 mmol/ g.