Selective extraction of mercury(II) from water samples using mercapto functionalised-MCM-41 and regeneration of the sorbent using microwave digestion

Silica sorbents, based on mesoporus crystalline material-41 (MCM-41), were functionalized using mercaptopropyl (MP) or diethylenetriamine (DETA) to extract mercury (II) ions from water. MP-MCM-41 was an extremely efficient and selective sorbent for the removal of mercury (II) from samples of distilled water doped with heavy metal ions, tap or river water. DETA-MCM-41 preferentially removed hard metal ions (chromium, manganese, lead and zinc) over soft metal ions such as mercury. During extraction, the influence of pH on adsorption capacity was examined; a maximum adsorption capacity of 1245 μmol g-1 was achieved for MP-MCM-41 even at pH values as low as 3. Significantly, a method has been developed, for the first time, to remove Hg (II) from loaded MP-MCM-41 allowing this analyte to be selectively removed from waters contaminated with a wide range of heavy metal ions. The regeneration method does not disrupt the chelating agent which remains on the surface of the silica permitting reuse of the sorbent in further extractions