Tuning the synthetic conditions of graphene oxide/magnetite/hydroxyapatite/cellulose acetate nanofibrous membranes for removing Cr (VI), Se(IV) and methylene blue from aqueous solutions

The discharge of high toxic contaminations of heavy metals and dyes to water resources has posed severe problems for the eco-system and human health. In this work, electrospun nanofibrous membranes of cellulose acetate containing fillers of graphene oxide (GO), magnetite nanoparticles (MNPs) or hydroxyapatite (HAP) were fabricated. It was shown that the membranes were configured in randomly oriented fibers with diameters around 0.11-0.35 mu m and 0.66-1.23 mu m, 0.14-0.33 mu m and 0.6-0.89 mu m, 0.17-0.37 mu m and 0.91-4.57 mu m 0.18-0.53 mu m and 1.18-2.1 mu m and 0.11-0.29 mu m for CA, GO@CA, MNPs@CA, HAP@CA and GO/MNPs/HAP@CA, respectively. The observed surface roughness tends to be promoted upon supplementations, as the roughness average (Ra) increased from 31.3 nm to 52 nm for CA and GO/MNPs/HAP@CA, respectively. The estimated toughness indicated that values increased from pristine CA reaching to its highest one at MNPs@CA as 2.5 +/- 0.2 MJ/m(3) to 8.2 +/- 0.5 MJ/m(3), respectively. The Se(IV) and Cr(VI) removal from aqueous solutions using the nanofibrous membranes was examined upon the time and pH value of the media. The removal efficiency for Se (IV) has improved from 89.3 % at pH 4-96 % for GO/MNPs/HAP@CA. Moreover, Cr(VI) removal progressed from 86.7, 86.3, 89.9, 90.6 and 92.9 % at pH 4-89.8, 90.5, 94.1, 94.7 and 97.3 % at pH 8 for CA, GO@CA, MNPs@CA, HAP@CA and GO/MNPs/HAP@CA, respectively. The degradation of methylene blue (MB) was investigated and reached its highest value of 95.1 % for GO/MNPs/HAP@CA after 35 min of continuous irradiation under visible light.