Adsorption of aliphatic polyhydroxy carboxylic acids on gibbsite: pH dependency and importance of adsorbate structure

Environmental Sciences Europe

Table 8 Experimental partition coefficients K_d at initial (P)HCA concentrations of 1.0 and 100 mmol L⁻¹ and parameters of the composite Langmuir–Freundlich isotherm for (P)HCA distribution in the gibbsite/ACPW system (pH 13.3)

(P)HCA	K ^a_d1,100 L kg⁻¹		X²/DoF	r ²	c ^b_sat ± S_D mmol kg⁻¹	K ^b_L ± S_D L mmol⁻¹	K ^b_F ± S_D mmol¹⁻ⁿ Lⁿ kg⁻¹	n^b ± S_D−
GLY	8.68	0.205	0.53	0.960	8.6 ± 1.6	1.35 ± 0.6	0.01 ± 0.02	1.57 ± 0.36
THR	18.6	n.a.	3.11	0.926	8.1 ± 1.3	4.0 ± 1.6	n.a.	n.a.
TAR	60.5	1.10	1.49	0.959	10.5 ± 4.4	8.77 ± 4.80	5.65 ± 2.02	0.61 ± 0.07
GLU	41.8	1.01	2.66	0.939	20.0 ± 3.2	3.15 ± 1.27	0.45 ± 0.24	1.13 ± 0.10
GLA	30.2	1.75	2.31	0.961	80.7 ± 11.4	0.22 ± 0.06	6.02 ± 1.70	0.52 ± 0.05

S_D, standard deviation; n.a., not applicable
^aDistribution coefficient K_d at initial (P)HCA concentrations of 1.0 and 100 mmol L⁻¹
^bComposite Langmuir–Freundlich isotherm parameter (Eq. 2)