**4. Characterization spectroscopic and thermal of catalyst**

The best value of copolymer yield was obtained with maghnite-H+ 0.25 M, in which there is a complete saturation of montmorillonite with protons without destruction of catalyst structure [31]. Maghnite-H+ was found to have a BET surface area (SSA) of 59.45 m2 /g, an average pore diameter of 62.46 Å and total pore volume of 0.00772 cm3 /g. The SSA of maghnite-H+ is close to that (61 m2 /g) obtained by Belbachir et al. [32] for montmorillonite.

After the activation process and filtration, the samples were washed until pH close to 7 and dried at 105°C overnight. According to experimental data, chemical composition of clay varies with the H2 SO4 concentration. Two regions can be revealed. In the region of 0.05–0.15 M H2 SO4 the change of Si/Al molar ratio is a small-scale due to the leaching of interlayer Ca2+, Mg2+ and Na+ cations by H2 SO4 . At the same time when H2 SO4 concentration is higher than 0.2 M the change of Si/Al molar ratio is pronounced that can be related to the dissolution of Al3+ cations from the octahedral sheet. Effect of the acid activation on the textural properties is also confirmed by XRD method. The X-ray of the samples are shown in **Figure 2a** and **b**. The position of the basal (001) reflection, i.e. interlayer distance, strongly depends on the H<sup>2</sup> SO4 concentration. The increasing H2 SO4 concentration from 0.05 to 0.25 M leads to increase the basal spacing, from 12.5 to 15.0 Å. However the basal spacing decreases again for higher acid concentrations. Probably, this phenomenon can be attributed to the "cleaning" of the solid due to the elimination of possible soluble impurities and the substitution of interlayer ions (Na+ and Ca2+) by H+ .

**Figure 2.** (a) XRD pattern of raw maghnite and activated maghnite (maghnite-H<sup>+</sup> ) [33] and (b) XRD profiles of maghnite-Na+ [34].

The thermal characterizations of the catalyst include thermogravimetric analysis (TGA). **Figure 3** shows the weight losses (%) versus temperature (°C) curves for pure maghnite-Na<sup>+</sup> . The TGA of pure maghnite-Na+ show two stages of weight loss. The first weight loss in Na<sup>+</sup> - Mag below 100°C is a result of the release of free water. The second weight loss around 600°C is associated with the dehydroxylation of silicate structure [35]. The total weight loss is only 13.94% up to 800°C. As can be expected, maghnite-Na<sup>+</sup> shows a high thermal stability.

for 20 min using a Prolabo ceramic balls grinder. It was then dried by baking at 105°C for 2 h. The maghnite was then weighed and placed in an Erlenmeyer flask together with 500 ml of distilled water. The maghnite/water mixture was stirred using a magnetic stirrer and combined with 0.25 M of sulfuric acid solution, until saturation was achieved over 2 days at room temperature, the mineral was washed with distilled water until it became sulfate free, and

there is a complete saturation of montmorillonite with protons without destruction

After the activation process and filtration, the samples were washed until pH close to 7 and dried at 105°C overnight. According to experimental data, chemical composition of clay var-

. At the same time when H2

0.2 M the change of Si/Al molar ratio is pronounced that can be related to the dissolution of Al3+ cations from the octahedral sheet. Effect of the acid activation on the textural properties is also confirmed by XRD method. The X-ray of the samples are shown in **Figure 2a** and **b**. The position of the basal (001) reflection, i.e. interlayer distance, strongly depends on the H<sup>2</sup>

basal spacing, from 12.5 to 15.0 Å. However the basal spacing decreases again for higher acid concentrations. Probably, this phenomenon can be attributed to the "cleaning" of the solid due to the elimination of possible soluble impurities and the substitution of interlayer ions

/g, an average pore diameter of 62.46 Å and total pore volume of 0.00772 cm3

the change of Si/Al molar ratio is a small-scale due to the leaching of interlayer Ca2+,

concentration. Two regions can be revealed. In the region of 0.05–0.15 M

SO4

concentration from 0.05 to 0.25 M leads to increase the

0.25 M, in which

/g.

SO4

was found to have a BET surface area (SSA) of

/g) obtained by Belbachir et al. [32] for

concentration is higher than

) [33] and (b) XRD profiles of

**4. Characterization spectroscopic and thermal of catalyst**

The best value of copolymer yield was obtained with maghnite-H+

is close to that (61 m2

then dried at 105°C [29, 30].

114 Characterizations of Some Composite Materials

The SSA of maghnite-H+

SO4

concentration. The increasing H2

and Ca2+) by H+

cations by H2

.

SO4

SO4

**Figure 2.** (a) XRD pattern of raw maghnite and activated maghnite (maghnite-H<sup>+</sup>

montmorillonite.

ies with the H2

Mg2+ and Na+

H2 SO4

(Na+

maghnite-Na+

[34].

59.45 m2

of catalyst structure [31]. Maghnite-H+

**Figure 4** shows the characteristic FT-IR spectra of Magh-Na+ and Magh-H+ . The characteristic absorption peaks of MMT are assigned to the Si–O–Si skeleton vibration at 1043–1116 cm−<sup>1</sup> , the strong absorption bands of Si–O and Al–O bending vibration at 525–628 cm−<sup>1</sup> and the OH stretching vibration at 3425 cm−<sup>1</sup> [36, 37].

**Figure 3.** TGA curves of a maghnite-Na+ obtained in nitrogen atmosphere at heating rate of 10°C/min.

**Figure 4.** FTIR spectra of raw-maghnite and maghnite-H+ .
