Adsorption of Pt(IV) and Pd(II) from Aqueous Solution by Calcined Gibbsite (Aluminum Hydroxide)

Abstract

In the present study, calcined gibbsite (GB) was prepared by calcination treatment between 200 and 1000 • C (GB200-GB1000). The properties of GBs (i.e., the amount of hydroxyl groups, specific surface area, mean pore diameter, and pore volume) were evaluated. GB400 had the highest amount of hydroxyl groups (0.46 mmol/g), as well as the highest specific surface area (295.3 m 2 /g) and micropore volume (0.036 mL/g). It also provided the highest amount of the adsorbed Pt(IV) and Pd(II), which suggests that the adsorption of Pt(IV) and Pd(II) onto GB is related to the amount of hydroxyl groups, specific surface area, and micropore volume. The optimal pH values for the adsorption of Pt(IV) and Pd(II) onto GB400 were 4.5-5.0 and about 6.0, respectively. The equilibrium adsorption of both cations onto GB400 was reached within 30 min. Moreover, the experimental data of the adsorption of Pt(IV) and Pd(II) onto GB400 was fitted by pseudo-second-order model (r = 0.997-0.999) and the Langmuir equation (r = 0.934-0.953). The calculated thermodynamic parameters ∆G, ∆H, and, ∆S indicate that the adsorption of Pt(IV) onto GB400 is feasible, spontaneous, and exothermic. In addition, the amount of Pt(IV) and Pd(II) adsorbed onto GB400 decreased with increasing chloride ion concentration.

New insight into electrochemical-induced synthesis of NiAl2O4/Al2O3: Synergistic effect of surface hydroxyl groups and magnetism for enhanced adsorptivity of Pd(II)

“…The higher selectivity for Pd 2+ ions in comparison to other noble metal ions may be due to the geometry square planar of Pd 2+ , which allows its fast adsorption, while more complex structures such as Pt 4+ and Au 3+ might require a longer time to be adsorbed. Similar phenomenon can be seen in the adsorption of platinum metal ions on other group metals (Pd, Pt, Rh) Fe 3 O 4 [40]. In general, the competitive adsorption ability varies from one metal ion to another and is related to a number of factors such as molecular mass, ion charges, hydrated ionic radius, and the hydration energy of the metals [41].…”

Adsorption of Au(III) from Aqueous Solution by Calcined Gibbsite

“…Moreover, the pseudo-second-order rate constant (k 2 ) of Pt(IV), Pd(II), and Mo(VI) adsorption on GB400 was greater than that of Au(III) adsorption, which suggest that GB400 was suitable for adsorption of Au(III) compared to Pt(IV), Pd(II), and Mo(VI). 27,17 Therefore, the data obtained in this study were characterized significantly better by the pseudo-secondorder model with respect to the pseudo-first-order model. The adsorption equilibrium of Au(III) between aqueous solution and GB400 can be described by an adsorption isotherm.…”

“…This study also observed a similar trend: the specific surface area and micropore volume showed a positive correlation. 17 Figure 1 shows the pH drift test for GB400. The pH of the zero charge, pH pzc , corresponds to that at which the curve crosses the straight line that fits the points pH initial = pH final .…”

Evaluation of the Interaction between Borate Ions and Nickel–Aluminum Complex Hydroxide for Purification of Wastewater

“…These results are consistent with previous studies. [20][21][22] Figure 2 shows XRD patterns of Al, Ni, and NA11. These demonstrate that Al, Ni, and NA11 have structures similar to gibbsite, β-Ni(OH) 2 , and nickel hydroxide, respectively.…”