Algal biosorption and biosorbents

Abstract

Algae belong to the kingdom Protista which contains all the Eucaryotes organisms that cannot be classified within other eucaryotic kingdoms: Fungi, Animalia or Plantae. They are autotrophic organisms that carry out an oxygenic photosynthesis. Maybe the most well-known use of algae since ancient times is in food, especially in the Asian coast. In addition, the phycocolloid industry uses algae as raw material in the manufacture of a wide variety of additive products in the cosmetic, pharmaceutical and food industries. Lately algae have been proposed for the treatment of wastewaters due to their high heavy metal sorption capacity. Although, traditionally they have been used in less extent than other biomass, algae have important advantages such as: high efficiency metal removal, non-toxic chemical sludge and low cost. The main kinds of algae (green, red and brown) have constituents (cellulose, carrageenan and alginate, respectively) that provide binding sites such as: hydroxyl, carboxyl, amino and sulfhydryl, which are responsible for the selectivity of these biomass for heavy metals. In this way, Fucus spiralis, a brown alga very common in the Galician coast, has been proved very selective in the sorption of copper versus other heavy metals. Like for other types of biomass, one way to improve its biosorbent capacity is by pre-treatment with different reagents. © 2011 Springer Science+Business Media B.V.