الملخص
Thestudy evaluates the possibility of pillaring calcium bentonite by polyhydroxy aluminum and iron solutions with various Al+3: OH- and Fe+3: OH- molar ratios according to the procedure: grinding, sieving, intercalation with aluminum and iron solutions, drying and calcination.
Polyhydroxy aluminum solution was synthesized as the following: aluminum chloride hydrate was prepared by reacting aluminum with dilute solution of hydrochloric acid. A solution with molarity 0.2M of aluminum chloride hydrate was prepared and mixed with prepared solution of sodium hydroxide (0.2M), stirred at room temperature then aged for 6 days. Three molar ratios of Al+3 to OH- were prepared 1: 1, 1: 2 and 1: 2.5.
Polyhydroxy iron solution was synthesized as the following: ferric chloride solution with molarity 0.2M was prepared, stirred with sodium hydroxide solution (0.2M) at room temperature then aged for 6 days. The molar ratios of Fe+3 to OH- were 1: 1, 1: 2 and 1: 2.5.
The intercalation between Al or Fe hydroxyl polymer with the clay was done by adding intercalation solution to bentonite clay (bentonite was suspended previously in distillated water, 1gram clay: 5 ml water), then resultants were filtered, washed, dried and calcined at 350, 450 and 550°C. The dependence of the basal spacing and thermal stability of Fe and Al- pillared clays were investigated by X-Ray diffraction. Cation exchange capacities were determined using methylene blue.
For Al –pillared clay calcined at 350°C, an increase of d-spacing (12.68, 13.50, and 14.63Å) were observed parallel to the Al+3: OH- ratio in pillaring solutions (1:1, 1:2, and 1:2.5 respectively). Pillared clay with ratio Al+3: OH- = 1: 2.5, calcined at 350°C, has surface area value 92.08 m2/g and d-spacing 14.63Å, while at the same calcinations temperature with Al+3: OH- molar ratio 1:1, d-spacing and surface area decreased to 12.68Å and 34.58 m2/g respectively.
Fe-pillared clay prepared by using Fe+3: OH- =1: 2 has the best stability in d- spacing after calcination at the different temperatures (ranged about 13.89-13.85 Å). Surface area value at calcination temperature 350°C was 139.74 m2/g, by increasing the calcination temperature to 550°C, the surface area decreased to 36.2 m2/g.
