Binding and Removal of Sulfate, Phosphate, Arsenate, Tetrachloromercurate, and Chromate in Aqueous Solution by Means of an Activated Carbon Functionalized with a Pyrimidine-Based Anion Receptor (HL). Crystal Structures of [H3L(HgCl4)]center dot H2O and [H3L(HgBr4)]center dot H2O Showing Anion-pi Interactions (vol 49, pg 9321, 2010)