Fig. 2 Recovery of As(V) and Se(IV) with (A) 0.25 M NH₂OH·HCl/0.25 M HCl; (B) 0.25 M NH₂OH·HCl/0.25 M HCl/0.1 M PO₄; (C) 0.1 M oxalic acid/0.175 M Na oxalate; (D) 0.1 M oxalic acid/0.175 M Na oxalate/0.1 M PO₄