Adsorption of Bisphenol A from Aqueous Solution by HDTMA-Tunisian Clay Synthesized Under Microwave Irradiation: A Parame
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ADSORPTION OF BISPHENOL A FROM AQUEOUS SOLUTION BY HDTMA-TUNISIAN CLAY SYNTHESIZED UNDER MICROWAVE IRRADIATION: A PARAMETRIC AND THERMODYNAMIC STUDY OUMAYA ISSAOUI1,2 *, HEDI BEN AMOR2, MOHAMED ISMAIL2, LAURENCE PIRAULT-ROY3, AND MOHAMED RAZAK JEDAY2 1 University of Gabes, Faculty of Sciences of Gabes, 6072 Gabes, Tunisia University of Gabes, Engineering School (ENIG), RL Processes, Energetic, Environment, and Electric Systems, 6072 Gabes, Tunisia 3 Université de Poitiers, CNRS UMR 7285, Institut de Chimie des Milieux et des Matériaux de Poitiers (IC2MP), B27, 4 rue Michel Brunet, 86073 Poitiers, Cedex 9, France
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Abstract—Bisphenol A (BPA), an endocrine disrupting compound, is of concern because of its wide presence throughout the environment and its harmful effects. The present study aimed to prepare an eco-friendly, low-cost, and efficient adsorbent for removal of BPA from wastewater. A natural Tunisian clay was used as a raw material. First, the clay was purified and then modified with hexadecyltrimethylammonium bromide (HDTMA) using microwave heating. The optimal conditions for clay modification were as follows: activation ratio = 0.3:(g/g), solid/liquid ratio = 5%, and microwave heating condition (2:min, 100:W). The purified and modified clays, abbreviated as HP and HMH, respectively, were characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and nitrogen adsorption/desorption analysis (BET). Adsorption tests were conducted in a batch reactor process under various conditions. The tests showed that the BET specific surface area of HMH is considerably smaller than that of HP, whereas the basal spacing increased from 14.99 to 22.07 Å after modification, indicating the success of HP organophilization. The adsorption of BPA onto HMH was not affected by the pH of solution between 2 and 10 and only slightly by temperature variation from 23 to 50°C, but was affected significantly by the initial concentration of BPA, contact time, and organo-clay dose. At equilibrium, the data obtained were fitted to Langmuir and Freundlich models. The best fit was obtained by the Langmuir model with a maximum monolayer adsorption capacity of 217.39 mg/g at 23°C. The thermodynamic study suggested that the removal of BPA by HMH was spontaneous (ΔG < 0), exothermic (ΔH < 0), and favorable. The present study demonstrated that HMH synthesized from an abundant and cheap natural clay could be used successfully as a low-cost adsorbent for the removal of BPA from wastewater. Keywords—Adsorption . Bisphenol A . Clay . Hexadecyltrimethylammonium bromide . Microwave INTRODUCTION Bisphenol A (BPA) is used widely, mainly as a monomer in the industrial production of polycarbonate plastics, epoxy resins, and as a non-polymer additive to other plastics (Bingzhi et al. 2010). The annual production of BPA is ~6.8 million tonnes (Jandegian et al. 2015) and release into the environment has exceeded 450 tonnes per year (USEPA 2010). Concentrations of BPA were reported to be between
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