Remoção dos contaminantes emergentes diclofenaco e ibuprofeno por adsorção em argilas aniônicas: processo em batelada

Abstract

Alternative methods for the removal of emerging contaminants through the adsorption process have been intensely studied in recent years. Pollutants such as the Diclofenac (DCF) and Ibuprofen (IBU) drugs of the class Nonsteroidal anti-inflammatory drugs (NSAIDs), because not require a prescription for acquisition these drugs, they are widely used in Brazil and the world, being in the group of medicines most found in water for human consumption, surface waters, raw sewage and effluents from Sewage Treatment Plants (TSEs), generating concerns related to public health issues and the ecological balance of ecosystems. In this context, the anionic clays of the type Layered Double Hydroxides (LDH), which are easy to obtain, low cost and high surface area which makes these materials promising as adsorbents of pollutants in aqueous medium. Then, in the present study, LDH [Co-Al-NO3] and [Zn-Al-NO3] were synthesized by the co-precipitation method at constant pH 8.0 ± 0.5. Subsequently, these materials were characterized structurally and morphologically and then applied as adsorbents of the drugs (Diclofenac and Ibuprofen) present in contaminated waters. LDH [Co-Al-NO3] used as an adsorbent for Diclofenac showed adsorption kinetics adjusted to the pseudosecond order model (R2 = 0.994), and the Freundlich isotherm (R2 = 0.991). The adsorption of Ibuprofen in LDH[Zn-Al-NO3] also adjusted to the pseudosecond order kinetic model (R2 = 0.994) and to the Freundlich model (R2 = 0.993) predominantly in relation to the Langmuir model (R2 = 0.9145). Physical adsorption favors the regeneration of the lamellar structure after the LDH under goes a heat treatment, and can be applied again to the process. In addition, the factorial design (23) of the adsorption of Ibuporphene showed that the highest removal rate of 76% (4.074 mg g-1) was obtained using 150 mg of LDH [Zn-Al-NO3], 20 mg L-1 of Ibupofen and pH 6. Therefore, the results indicated that the adsorption methods proposed by the LDHs are promising for the removal of drugs (Diclofenac and Ibuprofen) present in contaminated water and effluents.