Fabrication of nanoclay embedded adsorptive electrospun nanofiber membrane for removal of trace organic molecules

Abstract

This study aims to fabricate nanoclay (NC) embedded polyacrylonitrile (PAN) adsorptive electrospun nanofibers (Ads-ESNs) as high performance membranes for organic micropollutants (OMPs) removal. Ads-ESN were tested using a comprehensive protocol included adsorption in batches (static) and during filtration (dynamic). The filtration performance of Ads-ESNs was tested using gravity driven membrane (GDM) filtration using methylene blue (MB) as an adsorbate of similar characteristics to OMPs. The characterization was carried using SEM-EDS, FTIR and BET N2 adsorption/desorption technique. Addition of NC increased fiber diameters from 164 to 355 nm and surface areas from 12.9 to 45.9 m2/g. Accordingly, Ads-ESNs had 7 times higher adsorption capacity than PAN-ESN with isotherms fitting to Langmuir model (R2 = 0.9511–0.9899). The kinetics showed that adsorption in Ads-ESNs followed pseudo 1st and 2nd order indicating the occurrence of physisorption and chemisorption mechanisms simultaneously. pH and temperature effect were investigated and the results showed that highest adsorption occurred at pH 7 and 25 °C. The GDM system was operated at constant permeate flow rates of 1.0, 2.0 and 4.0 mL/min at 50mbar. MB rejection was over 90% at 1.0 and 2.0 mL/min of flow rates indicating the effect of applying lower flow rate and higher contact time. The adsorption capacities of Ads-ESN were different at static and dynamic adsorption due to different equilibrium states achieved at both adsorption modes. The fabricated Ads-ESNs showed outstanding removal performance for trace organic molecules even after four adsorption+filtration/regeneration cycles. Overall, this study demonstrated the potentials of combining membrane filtration and adsorption in a single-step process at same entity.