Adsorption of bisphenol A from aqueous solution onto organoclay: Experimental design, kinetic, equilibrium and thermodynamic study

Bisphenol-A (BPA) is a common plasticizer that has been considered a chemical of concern due to its endocrine disruption potential. In this sense, this paper aimed to investigate the adsorption of this contaminant onto commercial organophilic clay named Spectrogel (R) as means of water remediation. For this, characterization techniques were carried out before and post-process to identify any major alterations to the adsorbent due to BPA uptake. A statistical central composite rotational design (CCRD) technique was performed for process optimization. The impact of adsorbent dosage mass (0.128-1.472 g.100 mL-1, solution concentration (0.064-0.736 mmol/L-1) and particle diameter (0.28-1.0 mu m) on the adsorption capacity was analysed. It was defined 0.064 g of adsorbent dosage and an average particle size of 0.855 mu m as optimum conditions, in which a 0.193 mmol.g-1 (44.060 mg.g-1) adsorption capacity was obtained. Static adsorption assays showed that the kinetics better followed the external mass transfer resistance model, whilst the isotherm data obtained at 15 and 25 degrees C were well expressed by the Freundlich model and at 40 and 55 degrees C by the D-R model, achieving a maximum adsorptive capacity of 0.4 mmol.g-1 (91.316 mg.g-1). The thermodynamic parameters reflected a spontaneous and endothermic process. Furthermore, numerous eluent solutions were tested to assess the regenerability of the adsorbent and sodium hydroxide displayed the best desorption capacity (77.8%). The Spectrogel (R) clay has shown to be very promising as an alternative adsorbent in the remediation of water con-taminated with BPA. (c) 2021 Elsevier B.V. All rights reserved.