Sorption behavior of hydroselenide (HSe⁻) onto iron-containing minerals

Figures & data

Table 1. Experimental variables and data for Se(IV) sorption on goethite.

NaCl
0.01 mol dm^−3			0.1 mol dm^−3			1 mol dm^−3
pH	Rs (%)	Kd (m^3 kg^−1)	pH	Rs (%)	Kd (m^3 kg^−1)	pH	Rs (%)	Kd (m^3 kg^−1)
7.13	99	(1.6 ± 1.4) × 10^0	7.28	99	(1.6 ± 1.3) × 10^0	7.12	98	(6.4 ± 0.1) × 10^−1
7.46	99	(1.4 ± 1.0) × 10^0	8.02	99	(1.4 ± 1.1) × 10^0	8.00	97	(3.3 ± 0.1) × 10^−1
8.27	96	(2.7 ± 0.7) × 10^−1	9.45	96	(2.6 ± 0.1) × 10^−1	8.33	98	(4.6 ± 1.6) × 10^−1
9.08	95	(1.8 ± 0.4) × 10^−1	9.54	96	(2.3 ± 0.6) × 10^−1	8.47	98	(4.1 ± 1.2) × 10^−1
9.23	96	(2.5 ± 0.1) × 10^−1	10.33	92	(1.1 ± 0.2) × 10^−1	10.23	88	(7.2 ± 1.2) × 10^−2
10.27	90	(9.3 ± 0.2) × 10^−2	10.72	77	(3.3 ± 0.4) × 10^−2	10.55	78	(3.5 ± 0.5) × 10^−2
10.62	85	(5.6 ± 0.8) × 10^−2	11.23	40	(6.6 ± 1.2) × 10^−3	11.36	21	(2.6 ± 1.0) × 10^−3
11.46	22	(2.9 ± 1.0) × 10^−3	11.62	16	(1.9 ± 0.9) × 10^−3	11.47	15	(1.7 ± 1.0) × 10^−3
12.05	6	<1.4 × 10^−3	12.17	10	(1.1 ± 0.8) × 10^−3	11.51	17	(2.0 ± 1.0) × 10^−3
12.50	11	(1.3 ± 0.9) × 10^−3	12.53	4	<1.0 × 10^−3	11.66	13	(1.6 ± 1.0) × 10^−3
						11.73	14	(1.6 ± 1.0) × 10^−3
						11.75	18	(2.1 ± 1.0) × 10^−3
						12.18	10	(1.1 ± 0.8) × 10^−3
						12.41	7	<1.5 × 10^−3
						12.59	1	<7.5 × 10^−4

Table 2. Experimental variables and data for Se(IV) sorption on ferrous oxide.

NaCl
0.01 mol dm^−3			0.1 mol dm^−3			1 mol dm^−3
pH	Rs (%)	Kd (m^3 kg^−1)	pH	Rs (%)	Kd (m^3 kg^−1)	pH	Rs (%)	Kd (m^3 kg^−1)
8.53	100	(3.0 ± 2.7) × 10^0	8.42	100	>3.4 × 10^0	9.14	99	(1.5 ± 0.6) × 10^0
9.44	100	>3.3 × 10^0	9.24	99	(1.5 ± 1.2) × 10^0	9.79	99	>1.5 × 10^0
9.55	100	(3.5 ± 1.0) × 10^0	9.47	100	>2.1 × 10^0	10.53	38	(6.2 ± 1.6) × 10^−3
9.88	100	(2.7 ± 2.1) × 10^0	9.57	100	(2.6 ± 2.1) × 10^0	10.72	18	(2.2 ± 1.4) × 10^−3
9.94	97	(3.7 ± 1.3) × 10^−1	10.72	11	<2.3 × 10^−3	10.81	8	<1.9 × 10^−3
11.04	8	<1.9 × 10^−3	10.87	6	<1.7 × 10^−3	10.86	9	<2.1 × 10^−3
11.04	5	<1.5 × 10^−3	10.98	2	<1.2 × 10^−3	11.13	5	<1.6 × 10^−3
11.10	3	(2.7 ± 2.0) × 10^−4	11.39	2	<1.2 × 10^−3	11.32	3	<1.4 × 10^−3
12.03	3	(2.7 ± 2.0) × 10^−4	12.03	7	<1.8 × 10^−3	11.83	5	<1.6 × 10^−3
12.55	6	(6.0 ± 2.0) × 10^−4	12.61	10	<2.2 ×10^−3	12.46	7	<1.8 × 10^−3

Table 3. Experimental variables and data for Se(IV) sorption on magnetite.

NaCl
0.01 mol dm^−3			0.1 mol dm^−3			1 mol dm^−3
pH	Rs (%)	Kd (m^3 kg^−1)	pH	Rs (%)	Kd (m^3 kg^−1)	pH	Rs (%)	Kd (m^3 kg^−1)
7.10	99	(1.0 ± 0.4) × 10^0	7.02	99	(6.7 ± 1.6) × 10^−1	7.10	98	(5.8 ± 1.9) × 10^−1
7.21	99	(1.0 ± 0.4) × 10^0	7.08	99	(1.2 ± 0.5) × 10^0	7.22	98	(4.2 ± 0.6) × 10^−1
7.41	100	>4.5 × 10^0	7.10	99	(8.3 ± 2.4) × 10^−1	7.40	99	(8.3 ± 2.5) × 10^−1
7.43	98	(6.2 ± 2.0) × 10^−1	7.50	98	(6.4 ± 2.3) × 10^−1	7.45	98	(5.6 ± 1.8) × 10^−1
7.49	99	(1.2 ± 0.5) × 10^0	7.80	98	(6.0 ± 1.9) × 10^−1	8.10	98	(4.9 ± 1.4) × 10^−1
7.56	99	(1.0 ± 0.5) × 10^0	7.80	99	(8.0 ± 3.3) × 10^−1	8.20	98	(4.2 ± 1.1) × 10^−1
7.80	99	(6.6 ± 2.4) × 10^−1	8.10	99	(7.7 ± 3.2) × 10^−1	8.24	99	(8.5 ± 1.1) × 10^−1
7.90	99	(6.7 ± 2.4) × 10^−1	8.15	98	(4.7 ± 1.3) × 10^−1	8.31	99	(8.4 ± 4.3) × 10^−1
8.40	99	(1.7 ± 1.5) × 10^0	8.19	97	(3.1 ± 0.9) × 10^−1	8.83	94	(1.5 ± 0.2) × 10^−1
8.45	99	(1.2 ± 0.7) × 10^0	8.24	96	(2.5 ± 0.6) × 10^−1	9.24	98	(4.4 ± 0.3) × 10^−1
8.50	99	(7.8 ± 3.4) × 10^−1	8.50	98	(6.2 ± 2.2) × 10^−1	9.25	78	(3.6 ± 0.2) × 10^−2
8.59	99	(9.1 ± 1.2) × 10^−1	8.50	100	>4.6 × 10^0	9.41	71	(2.5 ± 0.1) × 10^−2
8.61	100	(3.5 ± 0.6) × 10^0	8.53	100	(2.6 ± 0.4) × 10^0	9.48	73	(2.7 ± 0.1) × 10^−2
8.64	95	(1.8 ± 0.3)×10^−1	8.89	99	(9.0 ± 1.2) × 10^−1	9.55	67	(2.0 ± 0.8) × 10^−2
8.75	99	(7.0 ± 0.8) × 10^−1	8.94	100	(4.2 ± 0.7) × 10^0	9.80	54	(1.2 ± 0.1) × 10^−2
8.90	98	(6.1 ± 0.7) × 10^−1	9.05	99	(9.0 ± 1.1) × 10^−1	9.95	17	(2.1 ± 0.3) × 10^−3
9.36	87	(6.8 ± 5.0) × 10^−2	9.25	98	(4.1 ± 0.3) × 10^−1	10.19	24	(3.2 ± 0.1) × 10^−3
9.89	50	(1.0 ± 0.4) × 10^−2	10.19	32	(4.8 ± 1.2) × 10^−3	10.25	21	(2.7 ± 1.0) × 10^−3
10.32	13	(1.5 ± 0.3) × 10^−3	10.31	20	(2.5 ± 0.4) × 10^−3	10.26	13	(1.4 ± 0.3) × 10^−3
10.51	6	(6.8 ± 3.3) × 10^−4	10.47	8	(8.1 ± 3.2) × 10^−4	10.56	7	<1.5 × 10^−3
10.58	23	(2.9 ± 1.0) × 10^−3	10.67	17	(2.0 ± 0.9) × 10^−3	10.83	11	(1.3 ± 0.3) × 10^−3
10.97	0	<3.8 × 10^−4	10.68	24	(3.2 ± 1.0) × 10^−3	11.05	4	<1.1 × 10^−3
11.23	3	<1.0 × 10^−3	10.95	4	(4.1 ± 3.2) × 10^−4	11.13	5	<1.2 × 10^−3
12.06	0	<3.3 × 10^−4	12.02	2	<5.1 × 10^−4	11.93	6	(6.9 ± 2.9) × 10^−4
12.30	0	<3.3 × 10^−4	12.30	2	<4.8 × 10^−4	12.19	6	(6.0 ± 2.9)× 10^−4

Table 4. Experimental variables and data for Se(IV) sorption on biotite.

NaCl
0.01 mol dm^−3			0.1 mol dm^−3			1 mol dm^−3
pH	Rs (%)	Kd (m^3 kg^−1)	pH	Rs (%)	Kd (m^3 kg^−1)	pH	Rs (%)	Kd (m^3 kg^−1)
7.06	95	(1.8 ± 0.6) × 10^−1	7.14	94	(1.7 ± 0.6) × 10^−1	7.11	96	(2.5 ± 1.3) × 10^−1
7.12	96	(2.2 ± 0.9) × 10^−1	7.20	94	(1.6 ± 0.5) × 10^−1	7.37	97	(3.3 ± 2.2) × 10^−1
7.56	95	(1.8 ± 0.6) × 10^−1	8.06	86	(6.3 ± 0.4) × 10^−2	7.48	95	(2.0 ± 0.8) × 10^−1
8.04	89	(8.0 ± 0.7) × 10^−2	8.52	67	(2.1 ± 0.1) × 10^−2	7.79	92	(1.1 ± 0.1) × 10^−1
8.26	84	(5.2 ± 0.6) × 10^−2	8.56	60	(1.5 ± 0.1) × 10^−2	7.85	89	(8.1 ± 0.7) × 10^−2
8.38	74	(2.8 ± 0.1) × 10^−2	8.79	57	(1.3 ± 0.2) × 10^−2	8.29	86	(6.0 ± 0.4) × 10^−2
8.47	66	(1.9 ± 0.1) × 10^−2	9.05	31	(4.4 ± 1.9) × 10^−3	8.45	65	(1.8 ± 0.3) × 10^−2
8.57	73	(2.7 ± 0.4) × 10^−2	9.05	30	(4.3 ± 1.9) × 10^−3	8.49	54	(1.2 ± 0.2) × 10^−2
8.64	76	(3.2 ± 0.4) × 10^−2	9.14	43	(7.6 ± 2.0) × 10^−3	8.55	65	(1.9 ± 0.3) × 10^−2
8.92	48	(9.3 ± 2.1) × 10^−3	9.31	29	(4.0 ± 1.9) × 10^−3	8.60	63	(1.7 ± 0.3) × 10^−2
9.23	45	(8.3 ± 2.1) × 10^−3	9.42	18	(2.2 ± 1.8) × 10^−3	8.62	52	(1.1 ± 0.2) × 10^−2
9.25	21	(2.7 ± 1.9) × 10^−3	9.68	15	<3.2 × 10^−3	8.63	48	(9.4 ± 2.1) × 10^−3
10.02	3	<1.7 × 10^−3	9.76	8	(8.6 ± 1.8) × 10^−4	8.64	50	(1.0 ± 0.2) × 10^−2
10.16	4	<1.9 × 10^−3	11.46	3	<1.7 × 10^−3	8.68	61	(1.5 ± 0.3) × 10^−2
12.30	1	<1.5 × 10^−3	11.89	3	<1.8 × 10^−3	8.72	34	(5.2 ± 1.9) × 10^−3
						8.81	52	(1.1 ± 0.1) × 10^−2
						8.81	42	(7.2 ± 2.0) × 10^−3
						8.93	50	(1.0 ± 0.1) × 10^−2
						8.98	28	(3.9 ± 1.9) × 10^−3
						9.01	41	(7.0 ± 0.3) × 10^−3
						9.07	27	(3.6 ± 1.9) × 10^−3
						11.05	8	<2.3 × 10^−3
						11.23	6	<2.1 × 10^−3
						11.57	2	<1.7 × 10^−3
						11.71	2	<1.6 × 10^−3

Figure 1. Comparison of K_d values for Se(IV) obtained in this study (open marks) and previously reported ones (closed marks) for (a) goethite [3,12,13,15], (b) ferrous oxide, (c) magnetite [21,27], and (d) biotite [3]. “0.01 M” represents the 0.01 mol dm⁻³ NaCl concentration. The previous data for ferrous oxide are not available.

Figure 2. Experimental conditions of equilibrated solutions in a pH–Eh diagram for the H–O–Se system under standard conditions. The total concentration of Se is 10⁻⁸ mol dm⁻³. The circles, squares, triangles, and asterisks represent the conditions for the sorption experiments using goethite, ferrous oxide, magnetite, and biotite, respectively.

Table 5. Experimental variables and data for Se(−II) sorption on goethite (using 0.1 g of the solid phase).

NaCl
0.01 mol dm^−3				0.1 mol dm^−3				1 mol dm^−3
pH	Eh (mV)	Rs (%)	Kd (m^3 kg^−1)	pH	Eh (mV)	Rs (%)	Kd (m^3 kg^−1)	pH	Eh (mV)	Rs (%)	Kd (m^3 kg^−1)
7.17	−220	99	(1.0 ± 0.8) × 10^1	7.90	−467	100	(3.2 ± 2.4)×10^1	7.28	−353	99	(1.9 ± 1.0)×10^1
7.98	−312	99	>1.1 × 10^1	8.08	−425	100	(3.3 ± 2.7)×10^1	7.59	−360	100	(3.1 ± 2.7)×10^1
8.02	−446	99	(1.6 ± 0.5) × 10^1	8.10	−287	98	(5.2 ± 1.5)×10^0	7.63	−329	100	>6.8 ×10^1
8.05	−287	98	(6.5 ± 3.8) × 10^0	8.29	−382	100	>8.0 × 10^1	7.89	−384	100	(2.4 ± 1.8) × 10^1
8.11	−285	98	(6.5 ± 3.8) × 10^0	8.39	−365	99	>1.5 × 10^1	7.90	−338	100	(3.8 ± 3.4) × 10^1
8.40	−362	98	(4.7 ± 0.6) × 10^0	8.42	−278	98	(5.8 ± 1.9) × 10^0	7.92	−333	99	(1.8 ± 0.9) × 10^1
8.41	−289	99	>1.3 × 10^1	8.43	−389	100	>2.3 × 10^1	8.13	−344	99	(7.6 ± 1.8) × 10^0
8.64	−399	95	(1.7 ± 0.1) × 10^0	8.57	−428	100	>9.0 × 10^1	8.15	−371	98	(4.4 ± 1.3) × 10^0
8.65	−301	99	(7.0 ± 5.0) × 10^0	8.57	−401	97	(3.4 ± 1.4) × 10^0	8.25	−416	97	(3.0 ± 0.4) × 10^0
8.65	−300	96	(2.7 ± 1.1) × 10^0	8.63	−368	98	(4.6 ± 1.9) × 10^0	8.39	−386	95	(1.8 ± 0.3) × 10^0
8.76	−302	97	(3.0 ± 1.0) × 10^0	8.70	−396	99	(9.6 ± 9.3) × 10^0	8.40	−368	99	>1.9 × 10^1
8.87	−314	98	(4.9 ± 2.5) × 10^0	8.76	−300	98	(6.1 ± 4.0) × 10^0	8.92	−340	94	(1.5 ± 0.1) × 10^0
9.01	−383	94	(1.5 ± 0.1) × 10^0	8.76	−321	99	(6.6 ± 2.4) × 10^0	8.97	−369	96	(2.1 ± 0.6) × 10^0
9.41	−326	98	(5.8 ± 3.5) × 10^0	8.86	−327	97	(3.8 ± 0.8) × 10^0	8.98	−405	93	(1.4 ± 0.3) × 10^0
10.05	−365	95	(1.8 ± 0.5) × 10^0	8.97	−312	96	(2.7 ± 1.3) × 10^0	9.50	−427	93	(1.3 ± 0.1) × 10^0
10.38	−316	90	(9.5 ± 1.3) × 10−^1	9.00	−339	96	(2.8 ± 0.4) × 10^0	9.83	−411	94	(1.6 ± 0.4) × 10^0
10.45	−338	96	(2.7 ± 0.9) × 10^0	9.53	−311	95	(1.9 ± 0.4) × 10^0	9.84	−436	91	(9.9 ± 0.2) × 10^−1
10.61	−367	92	(1.1 ± 0.2) × 10^0	9.70	−368	93	(1.4 ± 0.2) × 10^0	10.42	−462	83	(4.8 ± 0.6) × 10^−1
10.83	−369	93	(1.2 ± 0.3) × 10^0	9.89	−401	99	>1.7 × 10^1	10.55	−403	86	(6.3 ± 1.0) × 10^−1
10.95	−368	82	(4.5 ± 0.4) × 10^−1	9.98	−520	97	(2.8 ± 0.3) × 10^0	10.57	−395	96	(2.2 ± 0.5) × 10^0
11.05	−385	74	(2.8 ± 0.3) × 10^−1	10.14	−468	97	(3.4 ± 1.9) × 10^0	10.58	−388	92	(1.2 ± 0.2) × 10^0
11.16	−403	93	(1.4 ± 0.4) × 10^0	10.47	−470	97	(2.9 ± 0.9) × 10^0	10.68	−537	93	(1.3 ± 0.1) × 10^0
11.27	−411	87	(6.7 ± 1.0) × 10^−1	10.72	−481	87	(6.5 ± 0.9) × 10^−1	10.68	−324	79	(3.9 ± 0.2) × 10^−1
11.36	−435	83	(5.0 ± 0.6) × 10^−1	10.80	−469	91	(1.0 ± 0.2) × 10^0	10.89	−349	76	(3.1 ± 0.1) × 10^−1
11.49	−434	65	(1.8 ± 0.2) × 10^−1	11.12	−501	86	(6.0 ± 0.8) × 10^−1	10.89	−405	90	(9.3 ± 1.5) × 10^−1
11.50	−422	78	(3.6 ± 0.4) × 10^−1	11.23	−487	83	(5.0 ± 0.6) × 10^−1	10.96	−384	83	(4.7 ± 0.6) × 10^−1
11.51	−562	66	(1.9 ± 0.1) × 10^−1	11.28	−468	71	(2.5 ± 0.2) × 10^−1	11.00	−336	74	(2.8 ± 0.1) × 10^−1
11.61	−496	52	(1.1 ± 0.1) × 10^−1	11.31	−478	85	(5.6 ± 0.8) × 10^−1	11.07	−396	71	(2.5 ± 0.2) × 10^−1
11.64	−532	63	(1.7 ± 0.1) × 10^−1	11.51	−465	68	(2.1 ± 0.2) × 10^−1	11.09	−357	67	(2.0 ± 0.1) × 10^−1
11.68	−592	62	(1.6 ± 0.1) × 10^−1	11.57	−495	74	(2.9 ± 0.2) × 10^−1	11.16	−407	76	(3.1 ± 0.3) × 10^−1
11.70	−521	51	(1.1 ± 0.1) × 10^−1	11.58	−482	80	(4.0 ± 0.4) × 10^−1	11.30	−395	67	(2.0 ± 0.2) × 10^−1
11.72	−501	68	(2.1 ± 0.2) × 10^−1	11.59	−479	78	(3.6 ± 0.3) × 10^−1	11.34	−408	66	(1.9 ± 0.2) × 10^−1
11.72	−533	51	(1.0 ± 0.1) × 10^−1	11.63	−492	74	(2.8 ± 0.2) × 10^−1	11.36	−452	74	(2.9 ± 0.3) × 10^−1
11.77	−489	53	(1.1 ± 0.1) × 10^−1	11.65	−506	74	(2.9 ± 0.3) × 10^−1	11.39	−409	74	(2.9 ± 0.2) × 10^−1
11.87	−503	53	(1.1 ± 0.1) × 10^−1	11.67	−511	73	(2.8 ± 0.2) × 10^−1	11.40	−473	71	(2.4 ± 0.2) × 10^−1
12.01	−497	43	(7.5 ± 0.8) × 10^−2	11.70	−483	72	(2.6 ± 0.2) × 10^−1	11.47	−421	70	(2.3 ± 0.2) × 10^−1
12.14	−481	26	(3.5 ± 0.5) × 10^−2	12.03	−381	45	(8.3 ± 0.3) × 10^−2	11.52	−483	68	(2.1 ± 0.2) × 10^−1
12.28	−465	31	(4.5 ± 0.5) × 10^−2	12.07	−424	42	(7.3 ± 0.3) × 10^−2	11.91	−382	39	(6.4 ± 0.3) × 10^−2
12.55	−487	17	(2.1 ± 0.4) × 10^−2	12.43	−441	31	(4.4 ± 0.2) × 10^−2	11.92	−431	50	(9.9 ± 0.1) × 10^−2
12.66	−483	31	(4.5 ± 0.5) × 10^−2	12.46	−396	35	(5.4 ± 0.2) × 10^−2	12.33	−401	28	(3.9 ± 0.2) × 10^−2

Table 6. Experimental variables and data for Se(−II) sorption on goethite (using 1 g of the solid phase).

NaCl
0.01 mol dm^−3				0.1 mol dm^−3				1 mol dm^−3
pH	Eh (mV)	Rs (%)	Kd (m^3 kg^−1)	pH	Eh (mV)	Rs (%)	Kd (m^3 kg^−1)	pH	Eh (mV)	Rs (%)	Kd (m^3 kg^−1)
8.71	−361	100	(2.8 ± 1.7) × 10^0	8.58	−431	100	(4.6 ± 4.2) × 10^0	8.47	−441	100	(3.9 ± 3.4) × 10^0
8.72	−333	100	(2.8 ± 1.6) × 10^0	8.59	−362	100	(3.1 ± 1.9) × 10^0	8.54	−441	100	(3.9 ± 3.6) × 10^0
8.74	−316	100	(4.4 ± 4.0) × 10^0	8.60	−337	100	(2.5 ± 1.3) × 10^0	8.56	−411	100	(2.4 ± 1.3) × 10^0
8.75	−325	100	(2.5 ± 1.4) × 10^0	8.60	−335	100	(3.1 ± 1.9) × 10^0	8.63	−381	100	(2.4 ± 1.3) × 10^0
8.86	−421	98	(5.4 ± 0.7) × 10^−1	8.66	−326	100	(4.6 ± 4.2) × 10^0	8.69	−349	100	(3.3 ± 2.7) × 10^0
9.42	−336	100	(2.9 ± 2.3) × 10^0	9.03	−321	100	(4.6 ± 4.2) × 10^0	8.97	−361	100	(3.6 ± 3.1) × 10^0
9.48	−299	100	(4.0 ± 3.4) × 10^0	9.24	−311	100	>4.1 × 10^0	9.05	−366	100	(2.8 ± 1.8) × 10^0
9.97	−307	100	(2.9 ± 1.8) × 10^0	10.07	−311	100	(3.7 ± 2.8) × 10^0	9.40	−363	100	(3.9 ± 3.5) × 10^0
11.23	−494	95	(1.9 ± 0.1) × 10^−1	11.24	−421	96	(2.1 ± 0.1) × 10^−1	9.42	−336	100	>3.5 × 10^0
11.94	−463	94	(1.5 ± 0.1) × 10^−1	11.99	−465	92	(1.1 ± 0.0) × 10^−1	10.86	−355	96	(2.6 ± 0.2) × 10^−1
12.04	−483	90	(9.3 ± 0.3) × 10^−2	12.02	−472	92	(1.1 ± 0.0) × 10^−1	11.75	−432	87	(6.6 ± 0.2) × 10^−2
12.07	−497	88	(7.3 ± 0.2) × 10^−2	12.03	−478	87	(6.8 ± 0.2) × 10^−2	11.81	−443	93	(1.4 ± 0.1) × 10^−1
12.68	−485	72	(2.6 ± 0.1) × 10^−2	12.65	−496	68	(2.1 ± 0.0) × 10^−2	12.38	−486	66	(2.0 ± 0.1) × 10^−2

Table 7. Experimental variables and data for Se(−II) sorption on ferrous oxide.

NaCl
0.01 mol dm^−3				0.1 mol dm^−3				1 mol dm^−3
pH	Eh (mV)	Rs (%)	Kd (m^3 kg^−1)	pH	Eh (mV)	Rs (%)	Kd (m^3 kg^−1)	pH	Eh (mV)	Rs (%)	Kd (m^3 kg^−1)
7.79	−478	99	(1.1 ± 1.1) × 10^0	8.68	−453	98	(5.2 ± 3.1) × 10^−1	8.85	−398	99	(6.7 ± 6.1) × 10^−1
8.67	−460	99	>1.9 × 10^0	8.68	−468	97	(3.0 ± 0.9) × 10^−1	8.88	−516	99	>1.3 × 10^0
8.89	−298	94	(1.5 ± 0.3) × 10^−1	8.72	−537	99	(8.1 ± 6.3) × 10^−1	8.97	−423	99	>1.9 × 10^0
8.90	−352	99	(7.0 ± 4.2) × 10^−1	8.89	−491	99	>1.5 × 10^0	9.07	−400	97	(3.3 ± 1.6) × 10^−1
8.95	−396	100	>2.9 × 10^0	8.91	−488	99	>1.9 × 10^0	9.20	−421	99	>7.9 × 10^−1
8.95	−490	99	>1.9 × 10^0	8.92	−475	99	>9.4 × 10^−1	9.23	−549	99	>1.4 × 10^0
8.98	−426	96	(2.6 ± 0.6) × 10^−1	9.18	−501	99	>1.7 × 10^0	9.51	−567	85	(5.6 ± 0.5) × 10^−2
9.02	−497	99	>1.2 × 10^0	9.34	−511	97	(3.0 ± 1.0) × 10^−1	9.54	−523	94	(1.6 ± 0.3) × 10^−1
9.17	−485	98	(4.0 ± 1.4) × 10^−1	9.43	−566	99	>1.3 × 10^0	9.67	−425	98	(5.0 ± 3.3) × 10^−1
9.27	−488	99	(6.8 ± 4.6) × 10^−1	9.43	−486	99	>1.6 × 10^0	9.81	−506	98	(6.2 ± 5.1) × 10^−1
9.38	−472	100	>3.4 × 10^0	9.44	−509	99	(7.1 ± 4.3) × 10^−1	9.83	−529	71	(2.4 ± 0.2) × 10^−2
9.48	−486	99	(7.8 ± 6.1) × 10^−1	9.51	−471	99	>1.1 × 10^0	9.91	−456	74	(2.9 ± 0.3) × 10^−2
9.84	−539	99	(7.3 ± 5.2) × 10^−1	9.59	−468	99	(8.8 ± 8.7) × 10^−1	9.98	−417	90	(8.6 ± 1.4) × 10^−2
10.09	−436	99	>7.7 × 10^−1	9.66	−517	93	(1.3 ± 0.2) × 10^−1	10.06	−506	63	(1.7 ± 0.1) × 10^−2
10.24	−457	95	(2.0 ± 0.4) × 10^−1	9.78	−495	82	(4.5 ± 0.4) × 10^−2	10.45	−546	63	(1.7 ± 0.1) × 10^−2
10.52	−465	51	(1.1 ± 0.1) × 10^−2	10.18	−520	62	(1.6 ± 0.1) × 10^−2	10.62	−538	57	(1.3 ± 0.1) × 10^−2
10.57	−482	53	(1.1 ± 0.1) × 10^−2	10.61	−516	58	(1.4 ± 0.1) × 10^−2	10.69	−607	14	(1.7 ± 0.5) × 10^−3
10.83	−469	34	(5.1 ± 0.6) × 10^−3	10.73	−547	52	(1.1 ± 0.1) × 10^−2	10.72	−430	14	(1.6 ± 0.6) × 10^−3
10.93	−472	46	(8.4 ± 0.8) × 10^−3	10.75	−550	62	(1.6 ± 0.1) × 10^−2	10.94	−424	7	(7.4 ± 4.4) × 10^−4
11.19	−412	49	(9.6 ± 0.9) × 10^−3	10.87	−632	57	(1.3 ± 0.1) × 10^−2	10.97	−621	53	(1.1 ± 0.1) × 10^−2
11.53	−507	43	(7.6 ± 0.8) × 10^−3	11.23	−562	8	(9.2 ± 4.7) × 10^−4	11.04	−569	12	(1.4 ± 0.6) × 10^−3
11.58	−631	9	(1.0 ± 0.4) × 10^−3	11.24	−576	13	(1.5 ± 0.5) × 10^−3	11.25	−572	56	(1.3 ± 0.1) × 10^−2
12.15	−552	5	(5.4 ± 3.6) × 10^−4	11.38	−625	45	(8.0 ± 0.8) × 10^−3	11.84	−533	10	(1.1 ± 0.5) × 10^−3
12.32	−631	8	(8.2 ± 4.1) × 10^−4	11.42	−643	62	(1.7 ± 0.1) × 10^−2	11.93	−531	7	(7.4 ± 5.3) × 10^−4
12.49	−525	10	(1.1 ± 0.4) × 10^−3	12.03	−643	3	<6.8 × 10^−4	12.30	−581	4	<9.6 × 10^−4

Table 8. Experimental variables and data for Se(−II) sorption on magnetite.

NaCl
0.01 mol dm^−3				0.1 mol dm^−3				1 mol dm^−3
pH	Eh (mV)	Rs (%)	Kd (m^3 kg^−1)	pH	Eh (mV)	Rs (%)	Kd (m^3 kg^−1)	pH	Eh (mV)	Rs (%)	Kd (m^3 kg^−1)
7.61	−271	75	(2.9 ± 0.2) × 10^−2	7.11	−211	76	(3.1 ± 0.3) × 10^−2	7.32	−234	66	(2.0 ± 0.1) × 10^−2
7.77	−240	85	(5.6 ± 0.6) × 10^−2	7.34	−301	78	(3.5 ± 0.4) × 10^−2	7.41	−227	61	(1.5 ± 0.4) × 10^−2
7.81	−256	69	(2.3 ± 0.1) × 10^−2	7.46	−253	78	(3.5 ± 0.2) × 10^−2	7.57	−268	68	(2.2 ± 0.1) × 10^−2
7.87	−236	80	(4.1 ± 0.4) × 10^−2	7.48	−263	78	(3.4 ± 0.3) × 10^−2	7.66	−291	63	(1.7 ± 0.1) × 10^−2
7.91	−295	74	(2.8 ± 0.5) × 10^−2	7.51	−275	74	(2.8 ± 0.1) × 10^−2	7.81	−244	70	(2.4 ± 0.1) × 10^−2
7.93	−256	69	(2.2 ± 0.1) × 10^−2	7.82	−256	74	(2.8 ± 0.5) × 10^−2	7.87	−226	69	(2.2 ± 0.1) × 10^−2
8.00	−274	73	(2.7 ± 0.2) × 10^−2	7.83	−256	74	(2.9 ± 0.7) × 10^−2	8.02	−281	74	(2.9 ± 0.1) × 10^−2
8.12	−256	75	(3.0 ± 0.3) × 10^−2	7.84	−284	71	(2.5 ± 0.5) × 10^−2	8.05	−304	58	(1.4 ± 0.1) × 10^−2
8.15	−238	75	(3.1 ± 0.3) × 10^−2	7.88	−241	74	(2.8 ± 0.2) × 10^−2	8.19	−267	63	(1.7 ± 0.1) × 10^−2
8.20	−300	82	(4.6 ± 0.5) × 10^−2	7.89	−256	73	(2.7 ± 0.3) × 10^−2	8.24	−245	57	(1.3 ± 0.1) × 10^−2
8.35	−286	77	(3.4 ± 0.4) × 10^−2	7.90	−241	68	(2.1 ± 0.1) × 10^−2	8.35	−321	75	(3.0 ± 0.3) × 10^−2
8.37	−267	84	(5.3 ± 0.5) × 10^−2	8.00	−312	84	(5.2 ± 0.6) × 10^−2	8.46	−264	67	(2.0 ± 0.5) × 10^−2
8.49	−284	66	(1.9 ± 0.1) × 10^−2	8.02	−296	66	(2.0 ± 0.1) × 10^−2	8.49	−241	77	(3.3 ± 0.3) × 10^−2
8.50	−284	66	(1.9 ± 0.1) × 10^−2	8.09	−258	82	(4.7 ± 0.5) × 10^−2	8.51	−287	65	(1.9 ± 0.1) × 10^−2
8.51	−250	68	(2.2 ± 0.4) × 10^−2	8.21	−345	77	(3.4 ± 0.4) × 10^−2	8.52	−287	68	(2.2 ± 0.1) × 10^−2
8.55	−250	63	(1.7 ± 0.3) × 10^−2	8.22	−329	71	(2.4 ± 0.1) × 10^−2	8.60	−333	75	(3.0 ± 0.3) × 10^−2
8.57	−279	69	(2.2 ± 0.1) × 10^−2	8.49	−251	74	(2.8 ± 0.2) × 10^−2	8.64	−251	65	(1.8 ± 0.1) × 10^−2
8.68	−303	61	(1.6 ± 0.1) × 10^−2	8.50	−251	66	(2.0 ± 0.1) × 10^−2	8.69	−355	58	(1.4 ± 0.1) × 10^−2
8.74	−303	54	(1.2 ± 0.1) × 10^−2	8.51	−303	74	(2.8 ± 0.6) × 10^−2	8.72	−280	57	(1.3 ± 0.3) × 10^−2
8.77	−289	55	(1.2 ± 0.2) × 10^−2	8.60	−333	76	(3.1 ± 0.3) × 10^−2	8.74	−346	63	(1.7 ± 0.1) × 10^−2
8.77	−293	81	(4.2 ± 0.4) × 10^−2	8.60	−298	74	(2.8 ± 0.3) × 10^−2	8.79	−303	60	(1.5 ± 0.1) × 10^−2
8.77	−271	68	(2.1 ± 0.1) × 10^−2	8.63	−315	78	(3.6 ± 0.3) × 10^−2	9.00	−366	54	(1.2 ± 0.1) × 10^−2
8.79	−289	62	(1.6 ± 0.3) × 10^−2	8.67	−361	68	(2.1 ± 0.1) × 10^−2	9.02	−363	58	(1.4 ± 0.1) × 10^−2
8.86	−301	70	(2.4 ± 0.2) × 10^−2	8.69	−294	62	(1.6 ± 0.1) × 10^−2	9.04	−313	52	(1.1 ± 0.3) × 10^−2
8.97	−252	67	(2.0 ± 0.1) × 10^−2	8.71	−292	68	(2.1 ± 0.4) × 10^−2	9.06	−312	62	(1.6 ± 0.1) × 10^−2
9.04	−299	52	(1.1 ± 0.2) × 10^−2	8.72	−305	77	(3.4 ± 0.3) × 10^−2	9.06	−369	48	(9.4 ± 0.4) × 10^−3
9.05	−307	63	(1.7 ± 0.1) × 10^−2	8.74	−294	65	(1.9 ± 0.1) × 10^−2	9.09	−312	59	(1.4 ± 0.1) × 10^−2
9.06	−307	58	(1.4 ± 0.1) × 10^−2	8.92	−284	77	(3.4 ± 0.3) × 10^−2	9.12	−281	60	(1.5 ± 0.1) × 10^−2
9.37	−320	52	(1.1 ± 0.2) × 10^−2	9.00	−351	73	(2.7 ± 0.2) × 10^−2	9.54	−358	49	(9.7 ± 2.2) × 10^−3
9.38	−320	43	(7.7 ± 1.6) × 10^−3	9.05	−311	59	(1.5 ± 0.1) × 10^−2	9.56	−358	54	(1.2 ± 0.4) × 10^−2
9.41	−348	54	(1.2 ± 0.1) × 10^−2	9.05	−335	56	(1.3 ± 0.2) × 10^−2	9.58	−332	62	(1.6 ± 0.1) × 10^−2
9.42	−348	65	(1.9 ± 0.1) × 10^−2	9.05	−335	61	(1.5 ± 0.3) × 10^−2	9.69	−332	52	(1.1 ± 0.1) × 10^−2
9.62	−330	64	(1.8 ± 0.2) × 10^−2	9.19	−367	77	(3.3 ± 0.3) × 10^−2	9.69	−321	39	(6.4 ± 0.6) × 10^−3
9.91	−329	49	(9.8 ± 0.7) × 10^−3	9.23	−394	67	(2.0 ± 0.1) × 10^−2	9.69	−321	43	(7.6 ± 0.7) × 10^−3
10.12	−369	42	(7.1 ± 0.5) × 10^−3	9.30	−342	70	(2.4 ± 0.2) × 10^−2	9.74	−419	50	(9.8 ± 0.4) × 10^−3
10.21	−391	42	(7.1 ± 0.5) × 10^−3	9.34	−373	66	(1.9 ± 0.1) × 10^−2	10.03	−385	59	(1.5 ± 0.1) × 10^−2
10.24	−417	45	(8.1 ± 1.4) × 10^−3	9.39	−388	72	(2.6 ± 0.2) × 10^−2	10.10	−341	28	(3.9 ± 0.5) × 10^−3
10.24	−391	48	(9.3 ± 0.6) × 10^−3	9.42	−339	58	(1.4 ± 0.1) × 10^−2	10.10	−341	44	(7.9 ± 0.7) × 10^−3
10.26	−417	42	(7.3 ± 1.6) × 10^−3	9.44	−339	51	(1.0 ± 0.1) × 10^−2	10.14	−421	45	(8.1 ± 2.3) × 10^−3
10.36	−351	35	(5.4 ± 0.5) × 10^−3	9.66	−372	54	(1.2 ± 0.3) × 10^−2	10.15	−385	46	(8.4 ± 0.6) × 10^−3
10.42	−356	41	(6.9 ± 0.7) × 10^−3	9.68	−372	50	(1.0 ± 0.2) × 10^−2	10.20	−439	36	(5.6 ± 0.3) × 10^−3
10.51	−399	33	(4.9 ± 0.5) × 10^−3	10.19	−392	51	(1.0 ± 0.1) × 10^−2	10.28	−461	29	(4.1 ± 0.3) × 10^−3
10.72	−431	18	(2.2 ± 0.4) × 10^−3	10.39	−325	42	(7.3 ± 0.7) × 10^−3	10.29	−450	37	(5.9 ± 0.6) × 10^−3
10.82	−425	37	(6.0 ± 0.6) × 10^−3	10.46	−403	49	(9.6 ± 0.9) × 10^−3	10.34	−478	21	(2.7 ± 0.3) × 10^−3
10.83	−398	54	(1.2 ± 1.0) × 10^−2	10.63	−451	60	(1.5 ± 0.1) × 10^−2	10.43	−371	35	(5.5 ± 0.5) × 10^−3
11.01	−460	27	(3.7 ± 1.1) × 10^−3	10.70	−428	61	(1.6 ± 0.1) × 10^−2	10.56	−398	24	(3.1 ± 0.5) × 10^−3
11.06	−460	32	(4.6 ± 1.3) × 10^−3	10.76	−459	32	(4.7 ± 1.7) × 10^−3	10.63	−435	53	(1.1 ± 1.0) × 10^−2
11.06	−441	18	(2.3 ± 0.4) × 10^−3	10.81	−418	59	(1.4 ± 0.1) × 10^−2	10.73	−419	38	(6.1 ± 0.8) × 10^−3
11.11	−441	18	(2.2 ± 0.3) × 10^−3	10.93	−481	57	(1.3 ± 0.1) × 10^−2	10.87	−471	25	(3.4 ± 1.5) × 10^−3
11.16	−457	10	(1.1 ± 0.4) × 10^−3	10.95	−455	27	(3.8 ± 0.5) × 10^−3	10.91	−427	40	(6.6 ± 0.8) × 10^−3
11.22	−471	31	(4.5 ± 0.6) × 10^−3	11.12	−473	56	(1.2 ± 0.1) × 10^−2	10.92	−471	30	(4.2 ± 2.0) × 10^−3
11.29	−451	11	(1.2 ± 0.4) × 10^−3	11.17	−464	25	(3.3 ± 0.5) × 10^−3	10.95	−467	47	(8.8 ± 0.9) × 10^−3
11.39	−491	18	(2.2 ± 0.4) × 10^−3	11.20	−489	24	(3.2 ± 1.3) × 10^−3	11.18	−491	16	(1.9 ± 0.4) × 10^−3
11.41	−491	19	(2.4 ± 0.3) × 10^−3	11.27	−489	27	(3.7 ± 1.6) × 10^−3	11.24	−491	22	(2.9 ± 0.8) × 10^−3
11.53	−468	36	(5.6 ± 0.6) × 10^−3	11.28	−554	29	(4.2 ± 0.6) × 10^−3	11.25	−497	25	(3.3 ± 1.6) × 10^−3
11.57	−501	19	(2.3 ± 0.9) × 10^−3	11.33	−498	38	(6.1 ± 0.7) × 10^−3	11.58	−531	18	(2.1 ± 0.4) × 10^−3
11.62	−501	25	(3.4 ± 1.3) × 10^−3	11.57	−504	52	(1.1 ± 0.1) × 10^−2	11.60	−484	34	(5.2 ± 0.8) × 10^−3
11.79	−531	13	(1.5 ± 0.4) × 10^−3	11.77	−532	15	(1.7 ± 0.3) × 10^−3	11.68	−536	23	(2.9 ± 1.6) × 10^−3
11.84	−511	6	(6.8 ± 3.9) × 10^−4	11.87	−550	16	(1.8 ± 1.2) × 10^−3	11.68	−531	15	(1.8 ± 0.4) × 10^−3
11.86	−533	19	(2.3 ± 0.9) × 10^−3	12.59	−534	29	(4.1 ± 0.6) × 10^−3	11.93	−583	8	(8.5 ± 0.2) × 10^−4

Table 9. Experimental variables and data for Se(−II) sorption on biotite.

NaCl
0.01 mol dm^−3				0.1 mol dm^−3				1 mol dm^−3
pH	Eh (mV)	Rs (%)	Kd (m^3 kg^−1)	pH	Eh (mV)	Rs (%)	Kd (m^3 kg^−1)	pH	Eh (mV)	Rs (%)	Kd (m^3 kg^−1)
7.46	−288	86	(6.0 ± 0.6) × 10^−2	8.15	−333	81	(4.3 ± 0.4) × 10^−2	7.94	−263	82	(4.6 ± 0.5) × 10^−2
7.46	−332	93	(1.3 ± 0.3) × 10^−1	8.59	−325	89	(7.8 ± 1.0) × 10^−2	8.42	−310	80	(4.1 ± 0.4) × 10^−2
8.12	−296	80	(3.9 ± 0.3) × 10^−2	8.62	−295	83	(4.8 ± 0.5) × 10^−2	8.46	−328	87	(6.9 ± 1.0) × 10^−2
8.20	−321	85	(5.6 ± 0.6) × 10^−2	8.75	−268	80	(4.0 ± 0.4) × 10^−2	8.47	−333	82	(4.5 ± 0.5) × 10^−2
8.57	−375	84	(5.2 ± 0.5) × 10^−2	8.91	−337	90	(8.8 ± 1.3) × 10^−2	8.48	−293	82	(4.7 ± 0.5) × 10^−2
8.60	−372	85	(5.5 ± 0.6) × 10^−2	9.09	−301	81	(4.3 ± 0.4) × 10^−2	8.73	−331	89	(8.0 ± 1.2) × 10^−2
8.70	−300	77	(3.3 ± 0.3) × 10^−2	9.29	−344	90	(8.7 ± 1.2) × 10^−2	8.91	−351	78	(3.6 ± 0.3) × 10^−2
8.72	−314	88	(7.5 ± 1.0) × 10^−2	9.31	−400	81	(4.2 ± 0.3) × 10^−2	9.01	−306	74	(2.8 ± 0.3) × 10^−2
8.78	−298	86	(6.3 ± 0.7) × 10^−2	9.39	−348	90	(9.1 ± 1.3) × 10^−2	9.01	−333	86	(6.0 ± 0.7) × 10^−2
8.82	−351	87	(6.4 ± 0.7) × 10^−2	9.54	−407	82	(4.4 ± 0.4) × 10^−2	9.11	−336	86	(6.4 ± 0.8) × 10^−2
8.95	−382	84	(5.1 ± 0.5) × 10^−2	9.79	−414	81	(4.3 ± 0.4) × 10^−2	9.17	−387	87	(6.8 ± 0.7) × 10^−2
9.02	−393	79	(3.9 ± 0.4) × 10^−2	9.81	−398	78	(3.7 ± 0.3) × 10^−2	9.19	−339	88	(7.4 ± 1.1) × 10^−2
9.09	−402	77	(3.3 ± 0.3) × 10^−2	9.89	−419	88	(7.6 ± 1.0) × 10^−2	9.35	−392	86	(6.0 ± 0.6) × 10^−2
9.23	−387	84	(5.4 ± 0.5) × 10^−2	9.93	−363	89	(7.9 ± 1.0) × 10^−2	9.36	−345	88	(7.7 ± 1.2) × 10^−2
9.27	−378	87	(6.8 ± 0.8) × 10^−2	9.93	−402	75	(3.0 ± 0.2) × 10^−2	9.53	−396	88	(7.7 ± 0.9) × 10^−2
9.35	−389	84	(5.1 ± 0.5) × 10^−2	9.96	−430	85	(5.5 ± 0.6) × 10^−2	9.57	−382	75	(3.0 ± 0.3) × 10^−2
9.44	−401	80	(4.1 ± 0.5) × 10^−2	10.27	−433	93	(1.3 ± 0.3) × 10^−1	9.61	−406	83	(4.9 ± 0.4) × 10^−2
9.45	−351	84	(5.2 ± 0.5) × 10^−2	10.36	−378	83	(5.0 ± 0.5) × 10^−2	9.67	−400	84	(5.3 ± 0.5) × 10^−2
9.67	−403	79	(3.8 ± 0.4) × 10^−2	10.41	−368	72	(2.6 ± 0.2) × 10^−2	10.08	−362	86	(6.3 ± 0.8) × 10^−2
9.88	−452	77	(3.3 ± 0.2) × 10^−2	10.46	−438	90	(9.3 ± 1.3) × 10^−2	10.09	−415	87	(6.9 ± 0.7) × 10^−2
9.92	−410	58	(1.4 ± 0.1) × 10^−2	10.49	−382	79	(3.8 ± 0.3) × 10^−2	10.53	−421	71	(2.4 ± 0.2) × 10^−2
10.21	−399	71	(2.4 ± 0.2) × 10^−2	10.66	−443	85	(5.7 ± 0.5) × 10^−2	10.66	−453	70	(2.3 ± 0.2) × 10^−2
10.41	−423	56	(1.3 ± 0.1) × 10^−2	10.93	−425	62	(1.6 ± 0.1) × 10^−2	10.88	−389	54	(1.2 ± 0.1) × 10^−2
10.46	−443	68	(2.2 ± 0.1) × 10^−2	11.14	−413	58	(1.4 ± 0.1) × 10^−2	10.99	−433	55	(1.2 ± 0.1) × 10^−2
10.57	−452	52	(1.1 ± 0.1) × 10^−2	11.17	−395	60	(1.5 ± 0.1) × 10^−2	11.26	−426	42	(7.4 ± 0.9) × 10^−3
10.72	−411	62	(1.6 ± 0.1) × 10^−2	11.18	−452	67	(2.0 ± 0.1) × 10^−2	11.43	−472	55	(1.2 ± 0.1) × 10^−2
10.82	−413	66	(2.0 ± 0.2) × 10^−2	11.24	−412	69	(2.2 ± 0.2) × 10^−2	11.85	−493	44	(8.0 ± 0.8) × 10^−3
10.90	−406	67	(2.1 ± 0.1) × 10^−2	11.62	−472	70	(2.3 ± 0.2) × 10^−2	11.89	−507	45	(8.2 ± 1.0) × 10^−3
11.13	−501	61	(1.5 ± 0.1) × 10^−2	12.06	−503	31	(4.6 ± 0.5) × 10^−3	12.33	−470	30	(4.3 ± 0.6) × 10^−3
11.15	−457	44	(7.9 ± 0.7) × 10^−3	12.50	−530	35	(5.5 ± 0.5) × 10^−3	12.33	−532	33	(4.9 ± 0.6) × 10^−3
11.28	−436	49	(9.7 ± 0.9) × 10^−3
11.33	−472	43	(7.5 ± 0.8) × 10^−3
11.36	−468	45	(8.1 ± 0.7) × 10^−3
11.38	−520	52	(1.1 ± 0.1) × 10^−2
11.76	−412	50	(9.9 ± 0.9) × 10^−3
12.09	−465	24	(3.2 ± 0.5) × 10^−3
12.22	−461	21	(2.7 ± 0.5) × 10^−3
12.26	−462	44	(7.8 ± 0.7) × 10^−3
12.51	−491	37	(6.0 ± 0.6) × 10^−3
12.63	−491	27	(3.7 ± 0.5) × 10^−3

Figure 3. The K_d values for Se(−II) obtained in this study: (a) goethite, (b) ferrous oxide, (c) magnetite, and (d) biotite. Open marks and closed marks represent the data obtained using 1 g and 0.1 g of the solid phase, respectively.

Figure 4. Schematic drawing of the triple-layer model.

Figure 5. Comparison of R_s values of Se(IV) predicted using the TLM (lines) with experimentally measured ones (marks): (a) goethite, (b) ferrous oxide, (c) magnetite, (d) biotite (calculated with K^int_SeO3 = 10^15.1), and (e) biotite (calculated with K^int_SeO3 = 10^16.1).

Figure 6. Comparison of R_s values of Se(−II) predicted using the TLM (lines) with experimentally measured ones (marks): (a) goethite (using 0.1 g of the solid phase; assuming inner-sphere complexation), (b) goethite (0.1 g of the solid phase; outer-sphere complexation), (c) goethite (1 g of the solid phase; inner-sphere complexation), (d) goethite (1 g of the solid phase; outer-sphere complexation), (e) ferrous oxide (inner-sphere complexation), and (f) ferrous oxide (outer-sphere complexation).

Figure 7. Comparison of R_s values of Se(−II) predicted using the TLM (lines) with experimentally measured ones (marks): (a) magnetite (assuming inner-sphere complexation), (b) magnetite (outer-sphere complexation), (c) biotite (inner-sphere complexation), and (d) biotite (outer-sphere complexation).

Table 10. Model parameters and equilibrium constants for the TLM calculation.

			Goethite	Ferrous oxide	Magnetite	Biotite
Surface area	S	m^2 g^−1	17.6^a	0.2^a	1.6^a	4.6^a
Site density	ns	sites nm^−2	7.0^b	7.0	2.5^e	2.5
capacitance	C1	F m^−2	1.1^b	1.1	1.2^f	1.2
	C2	F m^−2	0.2^b	0.2	0.2^f	0.2
Equilibrium
constant			5.8^b	5.8	5.1^e	4.6^i
			–11.1^b	−11.1	–9.1^e	–6.4^i
	log K^intNa		–8.8^b	−8.8	–6.8^g	–6.8
	log K^intCl		8.0^c	8.0	8.0	8.0
			15.1^b	15.1	16.1^e	15.1
	log K^intHSe		6.0^d	6.0	−	−
	log K′^intHSe		−	−	12^h	12^h

Notes: The parameters for ferrous oxide were same as for goethite. The logK^int_Cl value for magnetite was same as that for goethite. The site density, capacitance, logK^int_Na, and logK^int_Clvalues for biotite were the same as those for magnetite. The logvalue for biotite was same as that for goethite.

^aObtained by Brunauer–Emmett–Teller method.

^bFrom Hayes et al. [12].

^cFrom Fukushi and Sverjensky [50].

^dDetermined by the least-squares fitting to the experimental data.

^eFrom Kim et al. [27].

^fFrom Sahai and Sverjensky [72].

^gFrom Criscenti and Sverjensky [75].

^hProvisional value estimated from the experimental data.

ⁱFrom Chakraborty et al. [76].

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