Dissolution and Solubility of the Synthetic Natroalunite and the Arsenic-Incorporated Natroalunite at pH of 2.00–5.60 and 25–45°C

Table 2

Analytical data and solubility product of the arsenic-incorporated natroalunite [Na_0.88(H₃O)_2.44Al_2.35(AsO₄)_0.38(SO₄)_1.62](OH)₆].

Temp (°C)	Initial pH	Time (h)	Analytical data (mmol/L)					log Ksp	Average log Ksp	(kJ/mol)	Average (kJ/mol)
			pH	Na	Al	AsO4	SO4
25	2.00	5760	3.98	16.477	0.666	0.161	6.744	−92.42	−92.30 ± 0.30	−5079	−5078 ± 2
		6480	4.09	16.614	0.592	0.151	7.110	−92.00		−5077
		7200	4.00	16.573	0.590	0.154	7.026	−92.47		−5079
25	2.00	5760	3.95	16.377	0.673	0.160	6.936	−92.59	−92.41 ± 0.37	−5080	−5079 ± 2
		6480	4.08	16.531	0.596	0.151	7.007	−92.04		−5077
		7200	3.96	16.466	0.630	0.155	6.950	−92.60		−5080
25	4.00	5760	4.88	13.771	0.015	0.106	7.634	−92.28	−92.04 ± 0.37	−5078	−5077 ± 2
		6480	4.99	13.860	0.017	0.109	7.602	−91.67		−5075
		7200	4.87	13.832	0.018	0.102	7.603	−92.15		−5078
25	5.60	5760	4.65	7.703	0.016	0.112	4.322	−93.21	−93.16 ± 0.26	−5084	−5083 ± 2
		6480	4.73	7.760	0.016	0.111	4.238	−92.90		−5082
		7200	4.62	7.601	0.016	0.108	4.394	−93.38		−5085
35	2.00	5760	3.70	11.048	1.011	0.204	4.746	−91.62	−91.38 ± 0.28
		6480	3.80	11.340	0.988	0.219	4.835	−91.10
		7200	3.74	11.392	0.990	0.214	4.846	−91.42
45	2.00	5760	3.61	10.770	0.886	0.194	4.598	−90.53	−90.36 ± 0.44
		6480	3.74	11.057	0.835	0.190	4.653	−89.92
		7200	3.61	11.011	0.819	0.196	4.684	−90.62