Chemical structure investigation of tropical Turbinaria turbinata seaweeds and its derived carbon sorbents applied for the removal of hexavalent chromium in water

Biomass such as algae, has a great potential to simultaneously deliver renewable energy, bio-products and also better water quality. A pathway towards the realization of these benefits is through the development of valuable materials preferably inexpensive. This work reports on the successful exploitation of Turbinaria turbinata, a brown alga widely available in many tropical areas; which was used as sorbent for the removal of hexavalent chromium from aqueous media. By characterizing the surface material, we showed that the dried alga exhibits several polyfunctional metal-binding sites, enabled to use it as a raw material. Further surface modification (pre-treatment with acid) and structural modification (preparation of both chemically and physically activated carbons) was also carried out to enhance material adsorption properties. Significant improvement of metal uptake (up to 40 fold higher) was obtained, depending of the testing conditions. Based on a close examination of the surface chemistry and pH profiles, a mechanism describing the adsorption mechanism of the different systems was proposed.