A method for making adsorbents for removing anions of a heavy metals is provided. In an example the method includes impregnating an adsorbent material with a solution comprising at least one compound of at least one metal selected from the group consisting of iron (II), aluminum, titanium, zirconium, and combinations thereof; and converting the compound into an oxygen-containing compound of said metal to produce said adsorbent capable of interacting with anions of the heavy metal. Such adsorbents are particularly useful for removing arsenic and/or selenium from the environment and may be used in treating drinking water sources.