EDA-SAMMS

EDA-SAMMS is an effective adsorbent for copper, nickel, cobalt and zinc in order of strength. Its greater strength is when it is metallized with copper or iron, or with ferrocyanate.

Chelate-SAMMS

Research and development is continuing on the preparation and testing of metal-chelating SAMMS. Chelating functional groups (such as EDA, ethylenediamine triacetic acid, pyridine, HOPO, etc.) are attached to the surface of the mesoporous materials using similar chemistry as is used for preparation of the Thiol-SAMMS. The chelating group is tailored for the targeted metal; for example, EDA for Cu and HOPO for the actinides.

Results have shown that selective removal of metal ions can be accomplished by various chelate-SAMMS and research is continuing to optimize the synthesis and metal loadings. Steward’s SAMMS can provide excellent solutions for removing scale formers in industrial process streams such as the bleaching process of the pulp and paper industry

Further modification of EDA-SAMMS can provide SAMMS with specificity very competitive with conventional ion exchange resins with faster kinetics, higher capacity and no swelling or shrinking in service. Elements successfully bound are cesium, arsenate, selenate and chromate.

Cu/Fe-EDA-SAMMS

Cu-EDA-SAMMS’ binding power for chromate is extremely good. Almost 100% removal was observed in an initial 100 ppm toxic metal anion solution under various experimental conditions. The anion loading is comparable to the heavy metal loading capacity achieved with Thiol-SAMMS when the stoichiometry and and atomic/molecular weight are considered. Even in the presence of 150 ppm sulfate, Cu-EDA SAMMS had a distribution coefficient of 105 ml/g. Below 1000 ppm chromate starts to saturate sites. Qualitatively similar results are shown for arsenate.

In summary, EDA-SAMMS can be effective in binding Ca and Mn in pulp and paper process streams. When the EDA-SAMMS ligand is further functionalized with copper or iron, it is a powerful adsorbent for arsenate and selenate. If combined with Thiol-SAMMS it offers an attractive treatment method for both valence states of arsenic and selenium (arsenate/arsenite and selenate/selenite)

When Cu-EDA-SAMMS is functionalized with ferrocyanide, it makes an exceptional adsorbent for cesium137. Cesium selectivity on a solution containing two parts per million (ppm) of cesium (similar to the radiocesium concentration of the relevant nuclear waste), found that the cesium concentration plummeted to less than four parts per billion (ppb) within one minute--that is, more than 99% of the cesium was complexed. Cesium levels declined further — to less than 1 ppb — within 2 hours.

Bulk density

The bulk density of SAMMS is ~ 0.3 g/cc.