Photonic crystals in biology - NanoTR-VI

PPoster Session, Thursday, June 17Theme F686 - N1123Preparation of Anion Exchange Membrane and Its Characterization by AFM and EFM111UZeynep ÇolakoluUP P*, Nilay GizliP P, Mustafa DemircioluP1PDepartment of Chemical Engineering, Ege University, Bornova, 35100, zmir, TurkeyAbstract-For the selective removal of arsenic species from water, a heterogeneous anion exchange membrane was prepared onpolyethylene backbone containing quaternized immobilized N-methyl-D-glucamine (NMDG). Surface characterization and electrostaticconductivity of this material were investigated by atomic force microscopy (AFM) and electrostatic force microscopy (EFM). Roughnessvalues show that materials have no porosity, while positive values of surface skewness (1.398) point to extreme peaks on the membranesurface and surface kurtosis (2.174) lower than 3.0 to broader height distributions. Characterization of materials by AFM and EFM servedfor both optimization of preparation conditions and improvement of material properties.Safety in drinking water is a challenge by climate change.Arsenic is important due to high toxicity and its high levelssome cities in Turkey. Main forms of arsenic met in groundwaters are arsenite or arsenate anions. Therefore theseparation by ion exchange comes as the first alternativemethod for ground waters. Removal performance of arsenicmust be enhanced for a viable industrial application. The aimof this study is to produce the anion exchange membranesand to characterize them by using AFM and EFM. Recentstudies show hopeful results in the name of using anionexchange membranes for the purification of water sourcesfrom hazardous ions since these membranes have excellentelectrochemical properties [1].In this study, membranes were prepared by aheterogeneous method, in which powdered ion exchangeresin of NMDG was combined with polyethylene, pressedand heated up till 250°C and kept for 10 min. Then themembrane was subjected to morphological andelectrochemical characterization. The surface structure ofmembranes was observed by multimode AFM (RT-SHPM,NanoMagnetics Instruments). The membrane surfaces werescanned by aluminium reflex coated silicon probe (Tap300AI, NanoMagnetics Instruments) having the springconstant of 40 N/m and the resonance frequency of 300 kHzin dynamic mode. Scan area and speed were chosen as210x10 μmP Pand 5 μ/s, respectively.The roughness parameters such as root mean squareroughness (RMS), mean roughness (Ra), average meanheight (Hav), surface skewness (Ssk) and surface kurtosis(Sku) were obtained by using built-in software SPM 1.16.13.It’s found that surface skewness was positive 1.398 which isalso numerically greater than 1.0 indicates that it has extremepeaks on the surface [2]. Surface Kurtosis was found as2.174 which is lower than 3.0, so the membrane showsbroader height distributions [3]. Imaging by EFM, anotherAFM technique, is used to characterize materials forelectrical properties. In this technique, a conductive AFM tipinteracts with the sample through long-range Coulombicforces. These interactions change both oscillation amplitudeand phase of AFM cantilever, which are monitored to createEFM phase image [4]. In this study, the voltage levels werechosen as -4V and +4V for forward and backward potentials.Scan speed of 8μm/s was applied for the samples with the2area of 30 x 30μmP P.Figure 1. AFM and EFM Phase views of membranes.The image at the left in Figure 1 is an AFM image onwhich lighter regions show peaks on the sample surface, onEFM image (to the right) lighter regions representconductive areas. Various properties were observed bychanging the parameters such as area scanned, scan speed,applied voltage, head lift, rising and falling time in order todetermine the optimum conditions for measurement. As aresult, before delving into experimental tests andperformance studies requiring large amount of material andlaborious tasks in a separation process, characterization ofmaterials by AFM and EFM during preparation phase ofthem helps both to screen the alternatives and to optimize thepreparation conditions for the development of novelselective materials and the improvement of their properties.*Corresponding author: HTzeynepcolakoglu@hotmail.comT[1] Punita V. Vyas, B.G. Shah, G.S. Trivedi, P. Ray, S.K.Adhikary, R. Rangarajan, Characterization of heterogeneous anionexchangemembrane, Journal of Membrane Science 187 (2001)[2] J. F. Jørgensen, L. L. Madsen, J. Garnaes, K. Carneiro, K.Schaumburg, Calibration, drift elimination and molecular structureanalysis, JVST B, 12(3), 1698-1701 (1994)[3] J. F. Jørgensen, N. Schmeisser, J. Garnaes, L. L. Madsen, K.Schaumburg, L. Hansen, P. Sommer-Larsen. (1994) Dynamicsand structure of selfassembled organic molecules at the solidliquidinterface, Journal of Surface & Coating Technology 67, pp.201-11[4] F. M. Serry, K. Kjoller, J. T. Thornton, R. J. Tench, and D.Cook. Electric Force Microscopy, Surface Potential Imaging, andSurface Electric Modification with the Atomic Force Microscope(AFM).6th Nanoscience and Nanotechnology Conference, zmir, 2010 674