Electrospun magnetic polyacrylonitrile-GO hybrid nanofibers for removing Cr(VI) from water

Graphene based nanocomposites powder posses an immense potential and contributes significantly in the field of water treatment applications. However, the major challenge is to separate these powder materials from the treated water, otherwise it may result in environmental pollution. In this work, Graphene oxide (GO) and Fe3O4 nanoparticles embedded polyacrylonitrile (PAN) nanofibers membrane (PAN-GO-Fe3O4) was developed by simple electrospinning technique, maintaining needle to collector distance of 15 cm, solution flow rate of 1 mL/h and applied DC voltage of 15 kV. The formation, composition, bonding, surface morphology, size, surface area, and magnetic properties of the prepared nanocomposites was analyzed by XRD, FTIR, Raman, XPS, FESEM, HRTEM, BET and VSM analytical techniques. The formation of cubic crystal structure of Fe3O4 was confirmed by XRD and HRTEM. The functionalization and surface composition of PAN-GO-Fe3O4 was confirmed by FTIR, Raman, XPS and FESEM-EDX analysis. The FESEM images revealed the formation of fine fibers of PAN-GO-Fe3O4 with diameter of 150-170 nm. The TEM image revealed that the spherical nanoparticles having diameter of 10-20 nm were decorated on the surface of PAN-GO. From the N-2 adsorption-desorption experiment, it was found that PAN-GO-Fe3O4 composite shows higher surface area (90.62 mg/g) than that of GO, PAN and Fe3O4. The saturation magnetization value of the PAN-GO-Fe3O4 nanofibers membrane was found to be 28.72 emu/g. The prepared PAN-GO-Fe3O4 membrane was used for remediation of highly toxic hexavalent chromium (Cr(VI)) ions from water by batch adsorption method. The effect of Cr(VI) adsorption was investigated by varying different parameters such as amount of adsorbent, pH, time and concentration. The above experimental results revealed that Cr(VI) adsorption by PAN-GO-Fe3O4 was pH dependent and maximum adsorption capacity was found to be 124.34 mg/g. Pseudo second order kinetic model and Langmuir isotherm model were best fitted to the experimental data of Cr(VI) removal with higher correlation coefficient (R-2) values. The negative value of Delta G(0) and positive value of Delta H-0 highlighted that the adsorption of Cr(VI) onto PAN-GO-Fe3O4 was spontaneous and endothermic process. The effect of co-existing ions and reusability test were carried out to reveal the effectiveness of the adsorbent material. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

Graphene-based nanocomposites were successfully developed using electrospinning technique for the removal of toxic hexavalent chromium ions from water, showing high adsorption capacity and fitting well with kinetic and isotherm models.