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1Adsorption of two widespread emerging water contaminants (atrazine and paracetamol) onto three 2 different activated carbons was investigated. The carbons were characterized and the influence of their 3 physicochemical properties on the adsorption performance of atrazine and paracetamol was evaluated. 4The adsorption equilibrium data were fitted to different adsorption isotherm models (Langmuir, 5Freundlich, and Dubinin-Radushkevich) while the adsorption rates were described using three different 6 kinetic models (pseudo second order, intraparticle diffusion and a new approach based on diffusion-7 reaction models). The results indicated that hydrophobic character of the compounds does not affect the 8 sorption capacity of the tested carbons but does influence the uptake rate. The model proposed, based on 9 mass balances, lead to interpret and compare the kinetic of different adsorbents in contrast to classical 10 empirical models. The model is a simple and powerful tool able to satisfactorily estimate the sorption 11 capacities and kinetics of the carbons under different operation conditions by means of only two 12 parameters with physical meaning. All the carbons studied adsorbed paracetamol more effectively than 13 atrazine, possibly due to the fact that sorption takes place by H-bonding interactions.14 Keywords: adsorption, paracetamol, atrazine, kinetics, diffusion model, sludge activated carbon 15 Introduction 16The emission of so-called "emerging contaminants" has arisen recently as an environmental problem. 17This group is mainly composed of compounds used in large quantities in everyday life, such as human 18 and veterinary pharmaceuticals, personal care products, surfactants, pesticides and different industrial 19 additives. Removal of some emerging contaminants in wastewater treatment plants (WWTP) was found 20 to be rather low due to the fact that most of them are resistant to biological degradation. Consequently 21 sewage effluents are one of the main sources of these compounds and their metabolites, which can 22 potentially end up in finished drinking water (Petrovic et al. 2003; de Ridder et al. 2010). 23One effective way to eliminate these recalcitrant compounds could be to introduce an adsorption 24 step before dumping WWTP effluents. Activated carbons are widely used to adsorb organic substances 25 from gases or liquids. They are commonly obtained from various organic precursors such as bituminous 26 coal, peat, wood, coconut shell (Marsh and Rodriguez-Reinoso, 2006). In recent years, there has been a 27 growing interest in converting organic waste materials with high carbon content into activated carbon 28 (Schröder et al. 2011). Sludge is waste material produced in large volumes in the sewage treatment plants. 29It can be recycled by composting and used in agricultural land, incinerated or used in landfills. Nowadays, 1 new environmentally benign alternatives for this residue are being sought. In this sense, sewage sludge 2 has been investigated as an attractive precursor for activat...

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The removal of Ni(II) and Cu(II) from aqueous solutions by a low cost sorbent (leonardite) was studied. The metal uptake was pH-dependent and the maximum sorption for two metals was obtained at around pH 5-6. Batch kinetic studies showed that equilibrium time was reached after 2 h of contact time. Equilibrium isotherms were obtained for the adsorption data of the two metals in single and binary systems. Equilibrium data were fitted to Langmuir and Freundlich models and the maximum adsorption capacities were found to be 0.33 mmol of copper and 0.26 mmol of nickel per gram of leonardite. In binary solutions containing the two metals an important reduction of nickel uptake was observed while the sorption of copper was less affected. The presence of Ca 2+ affected the removal of both copper and nickel ions, although the adsorption of nickel was reduced more than that of copper.