Removal of emerging pollutants present in water using an E-coli biofilm supported onto activated carbons prepared from argan wastes: Adsorption studies in batch and fixed bed

In order to improve the removal rates of paracetamol and amoxicillin present in water, activated carbons prepared from argan waste were designed as a support for a biofilm-based on E. coli yielding microporous materials with high surface areas, in such away that the biofilm support could be made homogeneously on the internal and external surface of the material. Adsorption studies without the presence of the biofilm showed rapid kinetics with adsorption constants k(PCT) = 0.06 and k(AMX) = 0.007 min(-1). The adsorption isotherms could be described by the Langmuir isotherm model reaching a maximum adsorption capacity of q(PCT) = 502 and q(AMX) = 319 mg g(-1). In contrast, the results obtained for the materials that support the biofilm showed slow kinetics (k(PCT) = 0.007 and k(AMX) = 0.003 min(-1)) and a remarkable change in the shape of the adsorption isotherms, since the experimental data are better represented by a combined Langmuir-Freundlich model, in which three important stages are observed: (i) In a first stage, adsorption is carried out in those spaces available after supporting the biofilm in the surface of the ACs. Once these spaces have been saturated, a second stage (ii) is present with an exponential behavior typical of the Freundlich isotherm, attributed to the adsorption of the pharmaceutical compounds in the biofilm, Finally a third stage is observed (iii) where the asymptotic behavior typical of the saturation of the adsorbent according to the Langmuir model is already appreciated (q(PCT) = 504 and q(AMX) = 465 mg g(-1)). (C) 2020 Elsevier B.V. All rights reserved.