Complexation of Arsenate to Humic Acid with Different Molecular Weight Fractions in Aqueous Solution

1. The dissolved organic carbon (DOC) concentration, carboxyl, and phenolic group contents, and total acidity of unfractionated HA and 5 HA fractions fractionated by ultrafiltration.2. Apparent stability constants (KS, mg/L), and maximum binding capabilities (Bmax, mg/L) of As(V) to HA fractions.3. Complexation of As(V) with unfractionated HA at different pH values (4.0, 7.0, and 10.0) and DOC concentrations of HA (5, 30, 100, 200 mg/L).4. Complexation of As(V) with HA fractions at different pH values (4.0, 7.0, and 10.0) (DOC = 30 mg/L).