RETRACTION: Pb(II) and Cd(II) removal, mechanical and morphological features of nanofibrous membranes of cellulose acetate containing fillers of hydroxyapatite, graphene oxide, and magnetite (Retraction of Vol 126, art no 819, 2020)

Heavy metal removal from polluted water is pivotal to keep the populations' health. In this issue, nanofibrous membranes of cellulose acetate (CA) filled with different compositions of graphene oxide (GO), hydroxyapatite (HAP), and magnetite nanoparticles (MNPs) were fabricated via electrospinning technique. The obtained phases were investigated via XRD, whereas both morphological features and roughness behaviors were characterized via FESEM. The membranes were configured as a non-oriented network with a wide range of diameters about 1.17-7.1, 1.6-4.6, 1.4-3.6, 0.92-1.8, 0.6-2.9 mu m for CA, GO@CA, MNPs@CA, HAP@CA and MNPs/HAP/GO@CA, respectively. On the other hand, grains of MNPs and HAP were detected as scattered spheres adhered to fibers' surfaces with diameters about 0.8-2.2 and 0.9-2.5 mu m, respectively. The maximum height of the roughness grew from 383.2 to 621.8 nm for CA and MNPs/HAP/GO@CA, respectively. Moreover, the mechanical properties were carried out and showed that the fracture strength increased exponentially from 16.2 +/- 1.1 to 28.5 +/- 2.3 MPa for CA and MNPs/HAP/GO@CA, respectively. The effectiveness of these membranes to remove Pb(II) and Cd(II) from aqueous solutions was investigated upon the pH variation and contact time. The highest values of removal efficiency upon pH variation reached 82.1, 85.8, 91.2, 92.1 and 99.1% for Pb(II) and 92.7, 93.3, 96.0, 98.7 and 99.3% for Cd(II), while upon changing of contact time, it maximized after 24 h of exposure to be about 86.2, 87.4, 94.5, 96.4 and 98.4% for Pb(II) and 90.5, 95.3, 95.6, 96.9 and 99.8% in case of Cd(II) for CA, GO@CA, MNPs@CA, HAP@CA and MNPs/HAP/GO@CA, respectively.