Abstract
The use of low-cost adsorbents is a good alternative to the traditional expensive materials, such as activated carbon, employing in the removal of organic micropollutants from wastewater. In this sense, a highly selective clay material, sepiolite Minclear SG36, for the removal of caffeine from aqueous solutions was used.
Sepiolite was characterized by FT-IR, SEM, TG/DTG and N2 adsorption-desorption isotherm techniques. Compared with activated carbon adsorbent, sepiolite adsorbent, with small particle size and high specific surface area, showed faster adsorption rate and middle adsorption capacity for caffeine. The equilibrium adsorption capacity obtained for caffeine by sepiolite was 20.0 mg g-1, and the adsorption equilibrium couldbe reached in 10 days. The adsorption isotherm was found to follow Dubinin-Radushkevich equation. The influence of several operation parameters, such as mass of adsorbent, volumetric flow rate and initial caffeine concentration, on the breakthrough time and the shape of breakthrough curves was evaluated.
In general, the studies of adsorption of micropollutants on clay minerals have been carried out in batch mode. For our knowledge, this is the first study about caffeine removal by a low-cost adsorbent, sepiolite, in adsorption fixed-bed columns.
