Calorimetry of Immersion in the Energetic Characterization of Porous Solids

Abstract

In order to study and understand the adsorption process in a liquid-solid interface, it is necessary to know both textural and chemical properties of the adsorbent. It is also important to know the behavior of the solid in a liquid medium, considering that the interaction can produce some changes in the texture and the electrochemical properties when the adsorbent is immersed in a solvent or a solution. The study of the influence of these properties in the adsorption process with techniques like immersion microcalorimetry can provide direct information on particular liquid-solid interactions. The parameter that is evaluated by immersion microcalorimetry is the immersion enthalpy, ΔH im. Immersion enthalpy is defined as the energy change at temperature and pressure constants when the surface of the solid is completely immersed in a wetting liquid in which the solid is insoluble and does not react. The immersion calorimetry can be a versatile, sensitive and precise technique that has many advantages for the characterization of porous solids. The versatility of immersion microcalorimetry is because changes in surface area, surface chemistry, or microporosity will result in a change in immersion energy. The interactions solid-liquid can be physical or chemical type, the physical present a lower amount of energy than that generated when exist chemical interactions.

Biogenic Hydroxyapatite Obtained from Bone Wastes Using CO2-Assisted Pyrolysis and Its Interaction with Glyphosate: A Computational and Experimental Study

“…Principally, it depends on the textural properties and surface chemistry of the solid as well as on the nature of the immersion liquid. 39 In general, immersion enthalpy is proportional to the surface area of the solid, which in our case is a very low surface area (5 m 2 •g −1 ). This was a limiting factor in our experiments, so we had to increase 4 times the mass of BHap in each experiment.…”

“…Principally, it depends on the textural properties and surface chemistry of the solid as well as on the nature of the immersion liquid. 39 …”

“…The thermal effect is measured and correlated to the immersion enthalpy, which is a thermodynamic parameter that depends on the system under study. Principally, it depends on the textural properties and surface chemistry of the solid as well as on the nature of the immersion liquid …”

Enthalpic Determination of the Interaction of Modified Activated Carbons with Benzene and Hexane as Pure Solvents and Binary Mixtures

“…This interaction depends on the properties of the solid (surface chemistry and porous structure) and the liquid (molecular size and arrangement, affinity to the adsorbent, polarity, etc.). The enthalpy of immersion is determined by immersion calorimetry, which is a highly accurate and sensitive technique (in the order of 10 to 100 mJ), allowing the evaluation of solid-liquid and solid-gas interactions; it is also used to generate complementary information regarding adsorption isotherms from the gas and liquid phase [8,9].…”

Comparative Study of Toluene and Hexane Adsorption on Activated Carbons From Gas and Liquid Phase. Enthalpy and Isotherms

“…In this technique is evaluated the energy required or produced by the immersion of a liquid into a porous solid and it is quite adequate to evaluate the energetic effect of the change in the concentration of the two adsorbates since its sensitivity is high, between 10 and 100 mJ, useful for determining interactions produced in solid-gas and solid-liquid interactions. Since this transfer of energy depends on the adsorbates and adsorbents, the determination H i also generates some added value because it can give an idea of the contribution of the change in the physicochemical properties of the solid, mainly the effect of surface chemistry on the adsorption process (Giraldo and Moreno-Piraján, 2007;Moreno-Piraján et al, 2011;Denoyel et al, 2014;Giraldo et al, 2018).…”