	Method	Na-sepiolite	Na-palygorskite	SiO₂ [24]	Al₂O₃ [24]	Kaolinite [27]
log k_a1int	Stumm	−6.0	−6.2	0.3	−7.2	−4.4
log k_a2int	Stumm	−10.5	−11.5	−7.2	−9.5	−9.2
½(pk_a1int + pk_a2int) [28] [29]		8.3	9.0	3.5	8.5	6.8
log k_a1	DDLM	-4	−5	-	-	-
log k_a2		−9.5	−9.5	-	-	-
log k_XH		1.5	1.5	-	-	-
log k_XNa		1	3	-	-	-
log k_X2Mg		5	5	-	-	-