Development of electromembrane extraction method by reusable membranes

Membrane technology is the most promising process for contaminations separation operation if the hydrophilicity, fouling and reusability properties could be improved. Superhydrophobicity property of the membrane surface diminishes interaction between the contaminations and membrane surface. This causes a reduction in the fouling tendency and self-cleaning characteristic. There are many methods to produce superhydrophobic properties such as layer-by-layer assembly, anodic oxidation grafting fluoroalkylsilane (FAS) on the membrane surface and electrospinning [1]. Electromembrane extraction (EME) has gained a lot of popularity among the researchers because of their aforementioned unique potentials such as high selectivity and high pre-concentrations [2]. In this study, we are focusing on fabricating a flat polymeric membrane that can be used in EME setup. Therefore, for the first time, reusable polyacrylonitrile (PAN)/polydimethylsiloxane (PDMS)/TiO2 nanofibrous flat membranes were fabricated by electrospinning process. The prepared membranes were characterized by FT-IR, AFM, EDAX, SEM and contact angle analysis. After that, their performance in electromembrane extraction of some ionizable phthalates, as model molecules were investigated. The affecting parameters on EME method were optimized by CCD experimental design. The optimum conditions were 200 V, 20 min, 1100 rpm, 10 ml and 1 ml for voltage, time, agitation rate, volumes donor and acceptor phases, respectively. Under these conditions, calibration curves in the range of 1-200 and 100-4000 ng/ml for diethylhexyl phthalate (DEHP) and dibuthyl phthalate (DBP) are linear with R2 0.990. The repeatability at two concentration levels (20 and 100 ng/ml) for DEHP and two concentration levels (15 and 2000 ng/ml) for DBP and at concentration of 200 ng/ml for the membrane-to-membrane were calculated. Relative standard deviation were less than 7, 9 and 12% for inter-day, intra-day and membrane-to-membrane, respectively. The limits of detection were found (0.08 and 7.4 ng/ml) and limits of quantification were (0.25 and 21.06) for DEHP and DBP, respectively. Three kinds of waters were used as real samples and the recoveries of those compounds in spiked water samples at a concentration of 20-2000 ng,/ml were obtained from 86-107%. On the optimum conditions the reusability study was performed too. The obtained results showed that the prepared membranes can be used at least 10 cycles without any loss in performance, as their RSD% was less than 6%