CHEMICAL ENGINEERING TRANSACTIONS VOL. 32, 2013 A publication of The Italian Association of Chemical Engineering Online at: www.aidic.it/cet Chief Editors: Sauro Pierucci, Jiří J. Klemeš Copyright © 2013, AIDIC Servizi S.r.l., I SBN 978-88-95608-23-5; I SSN 1974-9791 Low-Cost Adsorbent for Emerging Contaminant Removal in Fixed-Bed Columns Silvia Álvarez, José Luis Sotelo, Gabriel Ovejero, Araceli Rodríguez, Juan García* Grupo de Catálisis y Procesos de Separación (CyPS), Departamento de Ingeniería Química, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Avda. Complutense s/n, 28040 Madrid, Spain satorrellas@quim.ucm.es 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 N 2 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 could be 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. 1. Introduction Organic micropollutants as pharmaceutical compounds, endocrine disrupting compounds, pesticides and others, are present in the environment and due, to the increasing concentration detected in recent studies, are arise concern among researchers and regulatory agencies. Most of them are not yet regulated and their impacts on aquatic flora, animals and human life are not quite known. Thus, improved methods of analysis have identified these micropollutants at lower concentrations (μg L -1 to ng L -1 ). Caffeine is considered a chemical marker for surface water pollution due to it is regular consumed over the world. Therefore, it is one of the most abundant xenobiotic in untreated wastewater effluents together with its metabolite paraxanthine and the non-steroidal anti-inflammatory drug acetaminophen (Santiago-Morales et al. 2012). In order to remove these emerging contaminants from wastewaters varied physicochemical techniques have been proposed. Adsorption is an efficient and versatile method for the removal of low concentrations of organic pollutants from industrial wastewaters. Among commercial adsorbents, activated carbon is the most commonly used adsorbent. Adsorption on activated carbon has proven successfully in removing caffeine from aqueous solutions, showing a high adsorption capacity, 275 mg g -1 . Although it has great capacity of adsorbing various organic pollutants, activated carbon presents a relatively high price and difficulties in the possibilities of the regeneration (Sotelo et al. 2012). Researchers have investigated about low-cost adsorbents, such as natural clays which present high surface area and high porosity. Sepiolite [Si 12 Mg 8 O 30 (OH) 4 (OH 2 ) 4 8H 2 O] is a natural hydrated magnesium silicate clay mineral. Their structure presents blocks and channels running parallel to the fibre axis and provides great potential for retention of micropollutants such as heavy metals, cations, dyes and others. The studies of organic contaminants adsorption on clay minerals are usually developed in batch mode. 61