METHODS OF CHARACTERIZATION OF ADSORBATES-A REVIEW III
1.4 Characterization of Adsorbents
Being that adsorption capacity of adsorbents depends on surface area, pore structure and surface groups, polarity, solubility and molecule size of adsorbates; solution pH and the presence of other ions in solution; they need to be characterized by various analysis techniques so as to investigate and obtain information pertaining their physical structures and chemical properties.
It was also argued that application of solid adsorbents requires their characterisation which comprises the determination of their chemical composition, crystallographic and geometrical structure, surface and mechanical properties, and the energy distribution functions as well as the shape and size distribution of the pores within the materials so as to know their energetic heterogeneity and physical nature. When associated with additional independent measurements; such as calorimetric, spectroscopic and other ones; it gives valuable details on the correlation between the energy distribution of adsorption sites and their chemical nature. Also, the main purpose of characterization of adsorbents is to establish relationships between their properties and applications. It should be emphasized that not all the techniques are suitable for all adsorbents. While characterizing adsorbent, it is important to identify what specific characteristic is intended to study in order to choose the most appropriate techniques.
Thus surface area and pore structure can be determined by applying FTIR, X-Ray Diffraction (XRD), N2 physiosorption (BET), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM), electroanalytical techniques and many others to accomplish the mission.