REV.CHIM.(Bucharest)♦69♦No. 5 ♦2018 http://www.revistadechimie.ro 1233 Sorption of Bisphenol A in Aqueous Solutions on Irradiated and as-Grown Multiwalled Carbon Nanotubes RALUCA MADALINA SENIN 1,2 , ION ION 2 , OVIDIU OPREA 2 , RUSANDICA STOICA 1 , RODICA GANEA 1 , ALINA CATRINEL ION 2 * 1 National Research & Development Institute for Chemistry and Petrochemistry ICECHIM, 202 Splaiul Independentei, 060021, Bucharest, Romania 2 University Polkitehnica of Bucharest, 313 Splaiul Independentei , 060042, Romania In this study, non-irradiated and weathered multiwalled carbon nanotubes (MWCNTs) obtained through irradiation, were studied as adsorbents for BPA, both nanomaterials being characterized before and after the adsorption process. The objectives of our investigation were to compare the characteristics of non- irradiated and irradiated MWCNTs, to evaluate the adsorption capacity of BPA by pristine and irradiated MWCNTs and to determine the variation of the kinetic, sorption and thermodynamic parameters during sorption process using both sorbents. Keywords: sorption, bisphenol A, carbon nanomaterials, environment Endocrine disrupting chemicals (EDC) might have serious effects in the living bodies especially over the endocrine glands [1], this why their removal being important for environmental protection. Bisphenol A (BPA) has been reported in the environment, in rivers, seas and soils, being used in the production of polycarbonate and epoxy resins. It presents several risks to humans and to animals, this why its removal from the environmental matrices being intensively studied in the last years [2]. Especially in water treatment, adsorption is largely used for removing several organic [3] and inorganic [4] contaminants. Sorption of environmental contaminants to carbon based sorbents represents an important remediation solution [5], but in comparison with activated carbon, carbon based nanomaterials as environmental sorbents are considered relatively new adsorbents of trace pollutants, showing very good potential in future applications [6]. Multiwalled carbon nanotubes (MWCNTs) were investigated for removal of BPA [7], several studies demonstrating their suitability in sorption processes. Their adsorption capacity strongly depends on the surface chemistry, such as the density of surface active sites and the activation energy of the sorption bonds [8]. The transformation of the surface chemistry of MWCNTs depends on the matrices in which these nanostructures appear and on several factors that influence the nature and the number of the functional groups at the surface of MWCNTs. Among these, there are thermal and chemical oxidations and microwave-assisted heating, but also UV irradiation in controlled conditions in synthetic or in environmental media. Several articles [9] treat the impact of UV irradiation over the modification of the surface of MWCNTs, this factor being considered a dominant weathering element known to cause degradation outdoors. In this study, non-irradiated and irradiated MWCNTs, the last ones assimilated with weathered carbon nanomaterials were studied as adsorbents for BPA, both nanomaterials being characterized before and after the adsorption process. The irradiation experiments were conducted using UV irradiation with the same spectral regime as the UV portion of natural sunlight (300-400 nm), at environmental temperature and humidity. The objectives of our investigation were to compare the characteristics of non-irradiated and irradiated MWCNTs, to evaluate the adsorption capacity of BPA by pristine and irradiated MWCNTs and to determine the variation of the kinetic, sorption and thermodynamic parameters during sorption process using both sorbents. Experimental part Materials and methods Multiwalled carbon nanotubes ( MWCNTs) are provided by Baywatch, Germany. Irradiated MWCNTs were prepared in RWTH Aachen, Germany. Bisphenol A (minimum purity 99 %) was the sorbate selected for this study and it was obtained from Fluka/ Sigma-Aldrich Chemical, Germany. HPLC grade methanol was purchased from VWR Chemicals, France. Stock reference solutions were individually prepared in methanol, and kept in the refrigerator for three months. All working reference solutions were freshly prepared prior to use. Aqueous solutions were prepared using HPLC grade water. UV irradiated MWCNTs The experiments were conducted through not- accelerated aging using UV radiation in the UV spectral portion of natural sunlight (300-400 nm), at temperatures of 30-50 0 C and 50-75 % relative humidity. The UV chamber uses a mercury arc lamp system with a uniform UV flux of approx.140 W/m 2 , which can contain radiation in the visible range, but with very small impact over the degradation of the MWCNTs. The stability of the light source was carefully controlled during the experiments, no change in radiation intensity being noticed during one month of exposure. The relative humidity and the temperature were controlled using temperature and humidity sensors. HPLC analytical conditions HPLC determinations were performed using an Agilent 1100 Series HPLC instrument, with UV-DAD detector and Agilent Chemstation software for data acquisition and analysis. The working parameters of the method were: injection volume: 10 μ L; run time: 8 min; column temperature: 25 o C; column: C18 (Zorbax Eclipse Plus- Agilent), 3.5μm, 100 × 4.6 mm i.d.; flow rate: 0.5 mL/min, isocratic conditions at 80:20 A:B (v/v), where A = methanol and B = HPLC grade water. * Phone: 021 4029100