Spherical Activated Carbons with High Mechanical Strength Directly Prepared from Selected Spherical Seeds.

In the present manuscript, the preparation of spherical activated carbons (SACs) with suitable adsorption properties and high mechanical strength is reported, taking advantage of the retention of the spherical shape by the raw precursors. An easy procedure (carbonization followed by CO2 activation) has been applied over a selection of three natural seeds, with a well-defined spherical shape and thermal stability: Rhamnus alaternus (RA), Osyris lanceolate (OL), and Canna indica (CI). After the carbonization-activation procedures, RA and CI, maintained their original spherical shapes and integrity, although a reduction in diameter around 48% and 25%, respectively, was observed. The porosity of the resulting SACs could be tuned as function of the activation temperature and time, leading to a spherical activated carbon with surface area up to 1600 m²/g and mechanical strength similar to those of commercial activated carbons.

Capacitance of KOH activated carbide-derived carbons.

Chemical activation of CDC leads to capacitance values in an organic electrolyte as high as 180 F/g, 30% larger than those of as-produced samples, due to the surface area and microporosity development occurring as a consequence of the activation.

A new generation of sludge-based adsorbents for H2S abatement at room temperature.

The present paper discusses H2S removal by a new generation of sewage-sludge-derived materials which are characterized by their outstanding textural properties when compared to previous materials obtained by pyrolysis and/or activation of similar precursors. Alkaline hydroxide activation was used to prepare adsorbents/catalysts covering a wide range of porosities (SBET values from 10 to 1300 m2 g(-1)). Our results outline that textural properties are important for H2S abatement. However, not only highly porous sorbents, but also a high metallic content and a basic pH of these materials are required to achieve good performances. Proper combinations of textural properties and alkalinity render superior performances with retention values (x/M) as high as 456 mg of H2S removed per g of material. These retention capacities outperform previously published data for sewage-sludge derived materials and those achieved with commercial materials (including some activated carbons). Sulfur titration shows that most H2S is removed in the form of elemental sulfur, especially in the sewage/NaOH materials.