Ferric Sodium Edetate, also known as Sodium Iron EDTA, is a chemically synthesized compound with excellent stability and water solubility. In aqueous solutions, ferric sodium edetate exists as a stable complex, exhibiting outstanding thermal stability and heat resistance. This stability enables it to maintain structural integrity under high-temperature conditions without significant decomposition or degradation. However, when the temperature increases beyond a certain threshold, Ferric Sodium Edetate begins to undergo thermal decomposition, producing a series of new substances.
Thermogravimetric Analysis (TGA) of Ferric Sodium Edetate
Thermogravimetric Analysis (TGA) is a technique that monitors the mass changes of a sample as a function of temperature or time under a controlled temperature program (heating, cooling, or isothermal conditions). The following outlines the TGA of Ferric Sodium Edetate:
1. Experimental Conditions:
·Temperature Program: Heating, isothermal, etc.
·Atmosphere: Common atmospheres include oxygen, nitrogen, carbon dioxide, and water vapor. Variations in static or dynamic atmospheres may affect the results.
·Sample Quantity: A small sample amount facilitates the diffusion of gaseous products, reduces internal temperature gradients, and minimizes deviations between the sample and the linear heating environment. However, excessively small sample quantities place higher demands on the sensitivity, reproducibility, and signal-to-noise ratio of the thermobalance.
2. Thermogravimetric Curves:
·Gray Curve (TG): The thermogravimetric (TG) curve illustrates the change in sample weight as a function of temperature or time. Its vertical axis represents the weight percentage, indicating the ratio of the sample's current weight to its initial weight at a given temperature or time.
·Red Curve (DTG): The derivative thermogravimetric (DTG) curve depicts the rate of weight change as a function of temperature or time. The peaks on this curve correspond to the temperature or time points at which the weight change rate is maximized for each step of weight loss or gain.
3. Thermal Decomposition Process:
·100–200°C: Ferric Sodium Edetate primarily undergoes decarboxylation, producing ferric ethylenediaminetetraacetate (Ferric EDTA) and carbon dioxide. During this stage, the TG curve shows a significant mass loss, while the DTG curve displays a peak, indicating the temperature at which the mass loss rate is the highest.
·300–600°C: As the temperature increases, Ferric Sodium Edetate begins to decompose, generating a series of organic compounds (e.g., formaldehyde, formic acid, acetaldehyde, acetic acid) and inorganic substances (e.g., iron oxides and hydroxides). During this phase, the TG curve continues to indicate mass loss, and the DTG curve may display multiple peaks, reflecting variations in mass loss rates at different temperature points.
4. Applications:
·TGA can determine the mass loss behavior of Ferric Sodium Edetate at different temperatures, providing insights into its thermal stability and decomposition process.
·It enables analysis of the decomposition pattern, helping to study the degradation mechanism and reaction kinetics.
·TGA can quantify the organic and inorganic contents in ferric sodium edetate, supporting the chemical composition analysis of the material.
Ferric Sodium Edetate exhibits excellent thermal stability but undergoes thermal decomposition under high-temperature conditions. Through thermogravimetric analysis, the thermal decomposition process and the properties of its products can be thoroughly understood, offering valuable references for the application of Ferric Sodium EDTA.
