Table 2 Surface and mineralogical properties of gibbsite

Purity^a

99.4%

Density^a

2.4 g cm⁻³

Particle size^a (laser diffraction)

D₁₀ 0.3–0.5 µm

D₅₀ 0.7–1.2 µm

D₉₀ 1.2–2.7 µm

Surface area^a

10–12 m² g⁻¹

32 ± 25 m² g^−1b

Surface sites [≡SOH] (titration data)

120 mmol kg⁻¹, 2.4 mmol L⁻¹ (in batch)

8.2 ± 0.3 sites nm^−2c

6.02–7.23 sites nm⁻², mean: 6.57 sites nm⁻²

Isoelectric point (pH_IEP)

Diffuse double-layer model: pH: 8.28

9.1 ± 0.7^d

Constant capacitance model: pH: 8.04

Surface protonation constants

Diffuse double-layer model: pK_intr (+): 6.60, pK_intr(−): − 9.96

pK_intr (+): 7.17^e

Constant capacitance model: pK_intr (+): 5.66, pK_intr(−): − 10.41

pK_intr (−): − 11.18^e

pH (24 h, 5 mM NaClO₄)

9.12 ± 0.01