**3.3 Scanning electron micrographs and transmission electron microscopy**

SEM and TEM are used to collect detailed information on the morphology.

Msodek et al. [39] used SEM to determine the change in surface morphology of raw clay upon the intercalation of HDPy surfactant. Results showed that the photomicrography of raw clay exhibits massive and aggregate morphology (**Figure 5**). While, at low surfactant concentration (1.0 CEC ≤), the particles exhibit a compact form that can be explained by the interactions between the R groups of alkyl chains of surfactant. For the concentrations in exceeded the CEC of clay, the particles were changed to flat layers.

Using SEM and TEM, Pandey and De observed that the raw clay (bentonite) showed rough surface morphology however organo-bentonite showed a smooth surface with large size particles.

**Figure 5.** *Photomicrographs of clay and organoclays [39].*


#### **Table 2.**

*Physicochemical properties of the raw clay and organoclay.*

Thus Shirzad-Siboni et al. [42] employed SEM analysis to evaluate the surface morphology of the raw clay (montmorillonites,MMT) and organoclay (montmorillonite). Results reveal that the surface morphologies of both raw clay and organoclay have an uneven structure with non-uniform size distribution. The MMT shows massive, aggregated morphology, while, after modification, the clay surface was changed to a non-aggregated morphology with severely crumpled structures. Furthermore, the surface of Organoclay was expanded.

#### **3.4 Physicochemical properties**

The intercalation of surfactants in clay changes their Physicochemical properties (CEC, pore volume, Pore size, pHPZC…etc.).

Hamdi et al. noted that specific surface area decreases significantly as a function of the increase of exchanged surfactant in the specimen. The same results were obtained for the CEC and The pore volume (Vp). However, the value of PZC increased with the increase of exchanged surfactant in the raw clay. The SSA decrease indicates a compact packing of larger surfactant molecules between the silicate layers of mineral clay and blocking the passage of nitrogen molecules [63]. The same outcomes were reported by Pandey and De noted that The Pore size, surface area, as well as micro and mesopore volume, was drastically reduced after cationic surfactant treatment (**Table 2**).
