Efficient removal of Cu(II) with graphene oxide-titanium dioxide/sodium alginate composite beads: Preparation, characterization, and adsorption mechanism

Graphene oxide-titanium dioxide/sodium alginate (GO-TiO2/SA) composite beads are successfully prepared based on blending and cross-linking process, performing as adsorbent to remove Cu(II) in aqueous solution. Meanwhile, the cross-linking mechanism are explored and the morphology of the GO-TiO2/SA composite beads are characterized via FTIR, SEM, EDS, Raman and XPS. These results reveal that the porous network is created, corresponding to form hydrogen bonds, COTi among TiO2, GO and SA, as well as the cross-linking between carboxyl and Ca2+. In comparison with GO/SA composite beads, GO-TiO2/SA composite beads are endowed with a more integral porous structure and a larger specific surface area, observing from the characterizations of BET and SEM, confirming that better adsorption performance is achieved. Furthermore, the adsorption experiments of Cu(II) are carried out in terms of varying the dosage of the composite beads, temperature, pH and adsorption time. And the adsorption behavior can be better described by the pseudo-second-order kinetic model and Langmuir model. Importantly, GO-TiO2/SA composite beads maintain the undamaged structure and larger pore sizes when undergoing adsorption-desorption for two cycles. Finally, the adsorption mechanism on Cu(II) with GO-TiO2/SA composite beads is also explored via FTIR, EDS and XPS.